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Pavlin M, Škorja Milić N, Kandušer M, Pirkmajer S. Importance of the electrophoresis and pulse energy for siRNA-mediated gene silencing by electroporation in differentiated primary human myotubes. Biomed Eng Online 2024; 23:47. [PMID: 38750477 PMCID: PMC11097476 DOI: 10.1186/s12938-024-01239-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 04/23/2024] [Indexed: 05/18/2024] Open
Abstract
BACKGROUND Electrotransfection is based on application of high-voltage pulses that transiently increase membrane permeability, which enables delivery of DNA and RNA in vitro and in vivo. Its advantage in applications such as gene therapy and vaccination is that it does not use viral vectors. Skeletal muscles are among the most commonly used target tissues. While siRNA delivery into undifferentiated myoblasts is very efficient, electrotransfection of siRNA into differentiated myotubes presents a challenge. Our aim was to develop efficient protocol for electroporation-based siRNA delivery in cultured primary human myotubes and to identify crucial mechanisms and parameters that would enable faster optimization of electrotransfection in various cell lines. RESULTS We established optimal electroporation parameters for efficient siRNA delivery in cultured myotubes and achieved efficient knock-down of HIF-1α while preserving cells viability. The results show that electropermeabilization is a crucial step for siRNA electrotransfection in myotubes. Decrease in viability was observed for higher electric energy of the pulses, conversely lower pulse energy enabled higher electrotransfection silencing yield. Experimental data together with the theoretical analysis demonstrate that siRNA electrotransfer is a complex process where electropermeabilization, electrophoresis, siRNA translocation, and viability are all functions of pulsing parameters. However, despite this complexity, we demonstrated that pulse parameters for efficient delivery of small molecule such as PI, can be used as a starting point for optimization of electroporation parameters for siRNA delivery into cells in vitro if viability is preserved. CONCLUSIONS The optimized experimental protocol provides the basis for application of electrotransfer for silencing of various target genes in cultured human myotubes and more broadly for electrotransfection of various primary cell and cell lines. Together with the theoretical analysis our data offer new insights into mechanisms that underlie electroporation-based delivery of short RNA molecules, which can aid to faster optimisation of the pulse parameters in vitro and in vivo.
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Affiliation(s)
- Mojca Pavlin
- Institute of Biophysics, Faculty of Medicine, University of Ljubljana, Vrazov Trg 2, 1000, Ljubljana, Slovenia.
- Group for Nano and Biotechnological Applications, Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia.
| | - Nives Škorja Milić
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000, Ljubljana, Slovenia
- Institute of Anatomy, Faculty of Medicine, University of Ljubljana, Korytkova 2, Ljubljana, Slovenia
| | - Maša Kandušer
- Group for Nano and Biotechnological Applications, Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia
- Pharmacy Institute, Faculty of Pharmacy, University of Ljubljana, Ljubljana, Slovenia
| | - Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000, Ljubljana, Slovenia.
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Vidović A, Dolinar K, Chibalin AV, Pirkmajer S. AMPK and glucose deprivation exert an isoform-specific effect on the expression of Na +,K +-ATPase subunits in cultured myotubes. J Muscle Res Cell Motil 2024:10.1007/s10974-024-09673-9. [PMID: 38709429 DOI: 10.1007/s10974-024-09673-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Accepted: 04/24/2024] [Indexed: 05/07/2024]
Abstract
In skeletal muscle, Na+,K+-ATPase (NKA), a heterodimeric (α/β) P-type ATPase, has an essential role in maintenance of Na+ and K+ homeostasis, excitability, and contractility. AMP-activated protein kinase (AMPK), an energy sensor, increases the membrane abundance and activity of NKA in L6 myotubes, but its potential role in regulation of NKA content in skeletal muscle, which determines maximum capacity for Na+ and K+ transport, has not been clearly delineated. We examined whether energy stress and/or AMPK affect expression of NKA subunits in rat L6 and primary human myotubes. Energy stress, induced by glucose deprivation, increased protein content of NKAα1 and NKAα2 in L6 myotubes, while decreasing the content of NKAα1 in human myotubes. Pharmacological AMPK activators (AICAR, A-769662, and diflunisal) modulated expression of NKA subunits, but their effects only partially mimicked those that occurred in response to glucose deprivation, indicating that AMPK does not mediate all effects of energy stress on NKA expression. Gene silencing of AMPKα1/α2 increased protein levels of NKAα1 in L6 myotubes and NKAα1 mRNA levels in human myotubes, while decreasing NKAα2 protein levels in L6 myotubes. Collectively, our results suggest a role for energy stress and AMPK in modulation of NKA expression in skeletal muscle. However, their modulatory effects were not conserved between L6 myotubes and primary human myotubes, which suggests that coupling between energy stress, AMPK, and regulation of NKA expression in vitro depends on skeletal muscle cell model.
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Affiliation(s)
- Anja Vidović
- Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia
| | - Klemen Dolinar
- Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia
| | - Alexander V Chibalin
- Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
- National Research Tomsk State University, Tomsk, Russia
| | - Sergej Pirkmajer
- Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia.
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Pirkmajer S, Chibalin AV. Exit, O Sodium! Function (Oxf) 2024; 5:zqae018. [PMID: 38711930 PMCID: PMC11070877 DOI: 10.1093/function/zqae018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2024] [Revised: 04/03/2024] [Accepted: 04/03/2024] [Indexed: 05/08/2024] Open
Affiliation(s)
- Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana 1000, Slovenia
| | - Alexander V Chibalin
- Karolinska Institutet, Department of Molecular Medicine and Surgery, Integrative Physiology, Stockholm 17177, Sweden
- National Research Tomsk State University, Tomsk 634050, Russia
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Trstenjak-Prebanda M, Biasizzo M, Dolinar K, Pirkmajer S, Turk B, Brault V, Herault Y, Kopitar-Jerala N. Stefin B Inhibits NLRP3 Inflammasome Activation via AMPK/mTOR Signalling. Cells 2023; 12:2731. [PMID: 38067160 PMCID: PMC10798374 DOI: 10.3390/cells12232731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 11/24/2023] [Accepted: 11/26/2023] [Indexed: 12/18/2023] Open
Abstract
Stefin B (cystatin B) is an inhibitor of lysosomal and nuclear cysteine cathepsins. The gene for stefin B is located on human chromosome 21 and its expression is upregulated in the brains of individuals with Down syndrome. Biallelic loss-of-function mutations in the stefin B gene lead to Unverricht-Lundborg disease-progressive myoclonus epilepsy type 1 (EPM1) in humans. In our past study, we demonstrated that mice lacking stefin B were significantly more sensitive to sepsis induced by lipopolysaccharide (LPS) and secreted higher levels of interleukin 1-β (IL-1β) due to increased inflammasome activation in bone marrow-derived macrophages. Here, we report lower interleukin 1-β processing and caspase-11 expression in bone marrow-derived macrophages prepared from mice that have an additional copy of the stefin B gene. Increased expression of stefin B downregulated mitochondrial reactive oxygen species (ROS) generation and lowered the NLR family pyrin domain containing 3 (NLRP3) inflammasome activation in macrophages. We determined higher AMP-activated kinase phosphorylation and downregulation of mTOR activity in stefin B trisomic macrophages-macrophages with increased stefin B expression. Our study showed that increased stefin B expression downregulated mitochondrial ROS generation and increased autophagy. The present work contributes to a better understanding of the role of stefin B in regulation of autophagy and inflammasome activation in macrophages and could help to develop new treatments.
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Affiliation(s)
- Mojca Trstenjak-Prebanda
- Department of Biochemistry, Molecular and Structural Biology, Jožef Stefan Institute, SI-1000 Ljubljana, Slovenia
| | - Monika Biasizzo
- Department of Biochemistry, Molecular and Structural Biology, Jožef Stefan Institute, SI-1000 Ljubljana, Slovenia
- International Postgraduate School Jožef Stefan, SI-1000 Ljubljana, Slovenia
| | - Klemen Dolinar
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (K.D.); (S.P.)
| | - Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (K.D.); (S.P.)
| | - Boris Turk
- Department of Biochemistry, Molecular and Structural Biology, Jožef Stefan Institute, SI-1000 Ljubljana, Slovenia
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, SI-1000 Ljubljana, Slovenia
| | - Veronique Brault
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM, CNRS, Université de Strasbourg, 1 rue Laurent Fries, 67404 Illkirch Graffenstaden, France; (V.B.)
| | - Yann Herault
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM, CNRS, Université de Strasbourg, 1 rue Laurent Fries, 67404 Illkirch Graffenstaden, France; (V.B.)
- Institut Clinique de la Souris, PHENOMIN, CELPHEDIA, INSERM, CNRS, Universite’ de Strasbourg, 67404 Illkirch Graffenstaden, France
| | - Nataša Kopitar-Jerala
- Department of Biochemistry, Molecular and Structural Biology, Jožef Stefan Institute, SI-1000 Ljubljana, Slovenia
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Komel T, Omerzel M, Kamensek U, Znidar K, Lampreht Tratar U, Kranjc Brezar S, Dolinar K, Pirkmajer S, Sersa G, Cemazar M. Gene Immunotherapy of Colon Carcinoma with IL-2 and IL-12 Using Gene Electrotransfer. Int J Mol Sci 2023; 24:12900. [PMID: 37629081 PMCID: PMC10454179 DOI: 10.3390/ijms241612900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 08/12/2023] [Accepted: 08/15/2023] [Indexed: 08/27/2023] Open
Abstract
Gene immunotherapy has become an important approach in the treatment of cancer. One example is the introduction of genes encoding immunostimulatory cytokines, such as interleukin 2 and interleukin 12, which stimulate immune cells in tumours. The aim of our study was to determine the effects of gene electrotransfer of plasmids encoding interleukin 2 and interleukin 12 individually and in combination in the CT26 murine colon carcinoma cell line in mice. In the in vitro experiment, the pulse protocol that resulted in the highest expression of IL-2 and IL-12 mRNA and proteins was used for the in vivo part. In vivo, tumour growth delay and also complete response were observed in the group treated with the plasmid combination. Compared to the control group, the highest levels of various immunostimulatory cytokines and increased immune infiltration were observed in the combination group. Long-term anti-tumour immunity was observed in the combination group after tumour re-challenge. In conclusion, our combination therapy efficiently eradicated CT26 colon carcinoma in mice and also generated strong anti-tumour immune memory.
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Affiliation(s)
- Tilen Komel
- Department of Experimental Oncology, Institute of Oncology Ljubljana, Zaloska 2, SI-1000 Ljubljana, Slovenia; (T.K.); (M.O.); (U.K.); (K.Z.); (U.L.T.); (S.K.B.); (G.S.)
- Faculty of Medicine, University of Ljubljana, Vrazov trg 2, SI-1000 Ljubljana, Slovenia
| | - Masa Omerzel
- Department of Experimental Oncology, Institute of Oncology Ljubljana, Zaloska 2, SI-1000 Ljubljana, Slovenia; (T.K.); (M.O.); (U.K.); (K.Z.); (U.L.T.); (S.K.B.); (G.S.)
| | - Urska Kamensek
- Department of Experimental Oncology, Institute of Oncology Ljubljana, Zaloska 2, SI-1000 Ljubljana, Slovenia; (T.K.); (M.O.); (U.K.); (K.Z.); (U.L.T.); (S.K.B.); (G.S.)
| | - Katarina Znidar
- Department of Experimental Oncology, Institute of Oncology Ljubljana, Zaloska 2, SI-1000 Ljubljana, Slovenia; (T.K.); (M.O.); (U.K.); (K.Z.); (U.L.T.); (S.K.B.); (G.S.)
| | - Ursa Lampreht Tratar
- Department of Experimental Oncology, Institute of Oncology Ljubljana, Zaloska 2, SI-1000 Ljubljana, Slovenia; (T.K.); (M.O.); (U.K.); (K.Z.); (U.L.T.); (S.K.B.); (G.S.)
| | - Simona Kranjc Brezar
- Department of Experimental Oncology, Institute of Oncology Ljubljana, Zaloska 2, SI-1000 Ljubljana, Slovenia; (T.K.); (M.O.); (U.K.); (K.Z.); (U.L.T.); (S.K.B.); (G.S.)
| | - Klemen Dolinar
- Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Zaloska 4, SI-1000 Ljubljana, Slovenia; (K.D.); (S.P.)
| | - Sergej Pirkmajer
- Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Zaloska 4, SI-1000 Ljubljana, Slovenia; (K.D.); (S.P.)
| | - Gregor Sersa
- Department of Experimental Oncology, Institute of Oncology Ljubljana, Zaloska 2, SI-1000 Ljubljana, Slovenia; (T.K.); (M.O.); (U.K.); (K.Z.); (U.L.T.); (S.K.B.); (G.S.)
- Faculty of Health Sciences, University of Ljubljana, Zdravstvena pot 5, SI-1000 Ljubljana, Slovenia
| | - Maja Cemazar
- Department of Experimental Oncology, Institute of Oncology Ljubljana, Zaloska 2, SI-1000 Ljubljana, Slovenia; (T.K.); (M.O.); (U.K.); (K.Z.); (U.L.T.); (S.K.B.); (G.S.)
- Faculty of Health Sciences, University of Primorska, Polje 42, SI-6310 Izola, Slovenia
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Markota A, Kalamar Ž, Fluher J, Pirkmajer S. Therapeutic hyperthermia for the treatment of infection-a narrative review. Front Physiol 2023; 14:1215686. [PMID: 37565142 PMCID: PMC10410565 DOI: 10.3389/fphys.2023.1215686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 07/14/2023] [Indexed: 08/12/2023] Open
Abstract
Modulating body temperature, mostly through the use of antipyretics, is a commonly employed therapeutic intervention in medical practice. However, emerging evidence suggests that hyperthermia could serve as an adjuvant therapy for patients with infection. We performed a narrative review to explore the application of therapeutic hyperthermia in the treatment of infection. A number of studies have been performed in the pre-antibiotic era, enrolling patients with neurosyphilis and gonococcal infections, with reported cure rates at around 60%-80%. We have outlined the potential molecular and immunological mechanisms explaining the possible beneficial effects of therapeutic hyperthermia. For some pathogens increased temperature exerts a direct negative effect on virulence; however, it is presumed that temperature driven activation of the immune system is probably the most important factor affecting microbial viability. Lastly, we performed a review of modern-era studies where modulation of body temperature has been used as a treatment strategy. In trials of therapeutic hypothermia in patients with infection worse outcomes have been observed in the hypothermia group. Use of antipyretics has not been associated with any improvement in clinical outcomes. In modern-era therapeutic hyperthermia achieved by physical warming has been studied in one pilot trial, and better survival was observed in the hyperthermia group. To conclude, currently there is not enough data to support the use of therapeutic hyperthermia outside clinical trials; however, available studies are in favor of at least a temperature tolerance strategy for non-neurocritical patients.
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Affiliation(s)
- Andrej Markota
- Medical Intensive Care Unit, University Medical Centre Maribor, Maribor, Slovenia
- Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Žiga Kalamar
- Medical Intensive Care Unit, University Medical Centre Maribor, Maribor, Slovenia
| | - Jure Fluher
- Medical Intensive Care Unit, University Medical Centre Maribor, Maribor, Slovenia
- Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
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Zandona A, Madunić J, Miš K, Maraković N, Dubois-Geoffroy P, Cavaco M, Mišetić P, Padovan J, Castanho M, Jean L, Renard PY, Pirkmajer S, Neves V, Katalinić M. Biological response and cell death signaling pathways modulated by tetrahydroisoquinoline-based aldoximes in human cells. Toxicology 2023:153588. [PMID: 37419273 DOI: 10.1016/j.tox.2023.153588] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 06/30/2023] [Accepted: 07/03/2023] [Indexed: 07/09/2023]
Abstract
The uncharged 3-hydroxy-2-pyridine aldoximes with protonatable tertiary amines are studied as antidotes in toxic organophosphates (OP) poisoning. Due to some of their specific structural features, we hypothesize that these compounds could exert diverse biological activity beyond their main scope of application. To examine this further, we performed an extensive cell-based assessment to determine their effects on human cells (SH-SY5Y, HEK293, HepG2, HK-2, myoblasts and myotubes) and possible mechanism of action. As our results indicated, aldoxime having a piperidine moiety did not induce significant toxicity up to 300µM within 24hours, while those with a tetrahydroisoquinoline moiety, in the same concentration range, showed time-dependent effects and stimulated mitochondria-mediated activation of the intrinsic apoptosis pathway through ERK1/2 and p38-MAPK signaling and subsequent activation of initiator caspase 9 and executive caspase 3 accompanied with DNA damage as observed already after 4hour exposure. Mitochondria and fatty acid metabolism were also likely targets of 3-hydroxy-2-pyridine aldoximes with tetrahydroisoquinoline moiety, due to increased phosphorylation of acetyl-CoA carboxylase. In silico analysis predicted kinases as their most probable target class, while pharmacophores modeling additionally predicted the inhibition of a cytochrome P450cam. Overall, if the absence of significant toxicity for piperidine bearing aldoxime highlights the potential of its further studies in medical counter-measures, the observed biological activity of aldoximes with tetrahydroisoquinoline moiety could be indicative for future design of compounds either in a negative context in OP antidotes design, or in a positive one for design of compounds for the treatment of other phenomena like cell proliferating malignancies.
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Affiliation(s)
- Antonio Zandona
- Institute for Medical Research and Occupational Health, POB 291, HR-10001 Zagreb, Croatia.
| | - Josip Madunić
- Institute for Medical Research and Occupational Health, POB 291, HR-10001 Zagreb, Croatia.
| | - Katarina Miš
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.
| | - Nikola Maraković
- Institute for Medical Research and Occupational Health, POB 291, HR-10001 Zagreb, Croatia.
| | | | - Marco Cavaco
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal.
| | | | | | - Miguel Castanho
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal.
| | - Ludovic Jean
- Université Paris Cité, CNRS, INSERM, CiTCoM (UMR 8038), F-75006, Paris, France.
| | - Pierre-Yves Renard
- Normandie Univ, UNIROUEN, INSA Rouen, CNRS, COBRA (UMR 6014), 76000 Rouen, France.
| | - Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.
| | - Vera Neves
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal.
| | - Maja Katalinić
- Institute for Medical Research and Occupational Health, POB 291, HR-10001 Zagreb, Croatia.
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Miš K, Lulić AM, Marš T, Pirkmajer S, Katalinić M. Insulin, dibutyryl-cAMP, and glucose modulate expression of patatin-like domain containing protein 7 in cultured human myotubes. Front Endocrinol (Lausanne) 2023; 14:1139303. [PMID: 37033214 PMCID: PMC10073714 DOI: 10.3389/fendo.2023.1139303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 03/06/2023] [Indexed: 04/11/2023] Open
Abstract
Expression of patatin-like phospholipase domain containing protein 7 (PNPLA7), also known as neuropathy target esterase-related esterase (NRE), a lysophospholipase, increases with fasting and decreases with feeding in mouse skeletal muscle, indicating it is regulated by insulin, counterregulatory hormones, such as glucocorticoids and catecholamines, and/or nutrients. In cultured mouse adipocytes insulin reduces Pnpla7 expression, underscoring the possibility that insulin regulates PNPLA7 in skeletal muscle. The first aim of this study was to establish whether PNPLA7 is functionally expressed in cultured human skeletal muscle cells. The second aim was to determine whether PNPLA7 is regulated by insulin, glucocorticoids, cAMP/protein kinase A pathway, and/or glucose. Cultured human skeletal muscle cells expressed PNPLA7 mRNA and protein. Gene silencing of PNPLA7 in myoblasts reduced the phosphorylation of 70 kDa ribosomal protein S6 kinase and ribosomal protein S6 as well as the abundance of α1-subunit of Na+,K+-ATPase and acetyl-CoA carboxylase, indirectly suggesting that PNPLA7 is functionally important. In myotubes, insulin suppressed PNPLA7 mRNA at 1 g/L glucose, but not at low (0.5 g/L) or high (4.5 g/L) concentrations. Treatment with synthetic glucocorticoid dexamethasone and activator of adenylyl cyclase forskolin had no effect on PNPLA7 regardless of glucose concentration, while dibutyryl-cAMP, a cell-permeable cAMP analogue, suppressed PNPLA7 mRNA at 4.5 g/L glucose. The abundance of PNPLA7 protein correlated inversely with the glucose concentrations. Collectively, our results highlight that PNPLA7 in human myotubes is regulated by metabolic signals, implicating a role for PNPLA7 in skeletal muscle energy metabolism.
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Affiliation(s)
- Katarina Miš
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Ana-Marija Lulić
- Biochemistry and Organic Analytical Chemistry Unit, Institute for Medical Research and Occupational Health, Zagreb, Croatia
| | - Tomaž Marš
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
- *Correspondence: Sergej Pirkmajer, ; Maja Katalinić,
| | - Maja Katalinić
- Biochemistry and Organic Analytical Chemistry Unit, Institute for Medical Research and Occupational Health, Zagreb, Croatia
- *Correspondence: Sergej Pirkmajer, ; Maja Katalinić,
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Pirkmajer S, Garcia-Roves PM, Rustan AC, Chibalin AV. Editorial: Untangling energy metabolism in skeletal muscle: From physiology to pharmacology. Front Physiol 2022; 13:1113860. [PMID: 36589423 PMCID: PMC9795843 DOI: 10.3389/fphys.2022.1113860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 12/07/2022] [Indexed: 12/15/2022] Open
Affiliation(s)
- Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia,*Correspondence: Sergej Pirkmajer,
| | - Pablo M. Garcia-Roves
- Department of Physiological Sciences, School of Medicine, University of Barcelona, Barcelona, Spain
| | - Arild C. Rustan
- Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, Oslo, Norway
| | - Alexander V. Chibalin
- Department of Molecular Medicine and Surgery, Section of Integrative Physiology, Karolinska Institutet, Stockholm, Sweden,National Research Tomsk State University, Tomsk, Russia
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Zandona A, Zorbaz T, Miš K, Pirkmajer S, Katalinić M. Cytotoxicity-related effects of imidazolium and chlorinated bispyridinium oximes in SH-SY5Y cells. Arh Hig Rada Toksikol 2022; 73:277-284. [PMID: 36607726 PMCID: PMC9985343 DOI: 10.2478/aiht-2022-73-3688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Revised: 11/01/2022] [Accepted: 12/01/2022] [Indexed: 01/07/2023] Open
Abstract
Current research has shown that several imidazolium and chlorinated bispyridinium oximes are cytotoxic and activate different mechanisms or types of cell death. To investigate this further, we analysed interactions between these oximes and acetylcholine receptors (AChRs) and how they affect several signalling pathways to find a relation between the observed toxicities and their effects on these specific targets. Chlorinated bispyridinium oximes caused time-dependent cytotoxicity by inhibiting the phosphorylation of STAT3 and AMPK without decreasing ATP and activated ERK1/2 and p38 MAPK signal cascades. Imidazolium oximes induced a time-independent and significant decrease in ATP and inhibition of the ERK1/2 signalling pathway along with phosphorylation of p38 MAPK, AMPK, and ACC. These pathways are usually triggered by a change in cellular energy status or by external signals, which suggests that oximes interact with some membrane receptors. Interestingly, in silico analysis also indicated that the highest probability of interaction for all of our oximes is with the family of G-coupled membrane receptors (GPCR). Furthermore, our experimental results showed that the tested oximes acted as acetylcholine antagonists for membrane AChRs. Even though oxime interactions with membrane receptors need further research and clarification, our findings suggest that these oximes make promising candidates for the development of specific therapies not only in the field of cholinesterase research but in other fields too, such as anticancer therapy via altering the Ca2+ flux involved in cancer progression.
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Affiliation(s)
- Antonio Zandona
- Institute for Medical Research and Occupational Health, Zagreb, Croatia
| | - Tamara Zorbaz
- Institute for Medical Research and Occupational Health, Zagreb, Croatia
| | - Katarina Miš
- University of Ljubljana Faculty of Medicine, Institute of Pathophysiology, Ljubljana, Slovenia
| | - Sergej Pirkmajer
- University of Ljubljana Faculty of Medicine, Institute of Pathophysiology, Ljubljana, Slovenia
| | - Maja Katalinić
- Institute for Medical Research and Occupational Health, Zagreb, Croatia
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11
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Gros K, Matkovič U, Parato G, Miš K, Luin E, Bernareggi A, Sciancalepore M, Marš T, Lorenzon P, Pirkmajer S. Neuronal Agrin Promotes Proliferation of Primary Human Myoblasts in an Age-Dependent Manner. Int J Mol Sci 2022; 23:ijms231911784. [PMID: 36233091 PMCID: PMC9570459 DOI: 10.3390/ijms231911784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 09/06/2022] [Accepted: 09/22/2022] [Indexed: 12/02/2022] Open
Abstract
Neuronal agrin, a heparan sulphate proteoglycan secreted by the α-motor neurons, promotes the formation and maintenance of the neuromuscular junction by binding to Lrp4 and activating muscle-specific kinase (MuSK). Neuronal agrin also promotes myogenesis by enhancing differentiation and maturation of myotubes, but its effect on proliferating human myoblasts, which are often considered to be unresponsive to agrin, remains unclear. Using primary human myoblasts, we determined that neuronal agrin induced transient dephosphorylation of ERK1/2, while c-Abl, STAT3, and focal adhesion kinase were unresponsive. Gene silencing of Lrp4 and MuSK markedly reduced the BrdU incorporation, suggesting the functional importance of the Lrp4/MuSK complex for myoblast proliferation. Acute and chronic treatments with neuronal agrin increased the proliferation of human myoblasts in old donors, but they did not affect the proliferation of myoblasts in young donors. The C-terminal fragment of agrin which lacks the Lrp4-binding site and cannot activate MuSK had a similar age-dependent effect, indicating that the age-dependent signalling pathways activated by neuronal agrin involve the Lrp4/MuSK receptor complex as well as an Lrp4/MuSK-independent pathway which remained unknown. Collectively, our results highlight an age-dependent role for neuronal agrin in promoting the proliferation of human myoblasts.
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Affiliation(s)
- Katarina Gros
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Urška Matkovič
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Giulia Parato
- Department of Life Sciences, University of Trieste, 34127 Trieste, Italy
- The B.R.A.I.N. Centre for Neuroscience, University of Trieste, 34127 Trieste, Italy
| | - Katarina Miš
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Elisa Luin
- Department of Life Sciences, University of Trieste, 34127 Trieste, Italy
- The B.R.A.I.N. Centre for Neuroscience, University of Trieste, 34127 Trieste, Italy
| | - Annalisa Bernareggi
- Department of Life Sciences, University of Trieste, 34127 Trieste, Italy
- The B.R.A.I.N. Centre for Neuroscience, University of Trieste, 34127 Trieste, Italy
| | - Marina Sciancalepore
- Department of Life Sciences, University of Trieste, 34127 Trieste, Italy
- The B.R.A.I.N. Centre for Neuroscience, University of Trieste, 34127 Trieste, Italy
| | - Tomaž Marš
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Paola Lorenzon
- Department of Life Sciences, University of Trieste, 34127 Trieste, Italy
- The B.R.A.I.N. Centre for Neuroscience, University of Trieste, 34127 Trieste, Italy
- Correspondence: (P.L.); (S.P.)
| | - Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
- Correspondence: (P.L.); (S.P.)
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12
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Ravnihar K, Marš T, Pirkmajer S, Alibegović A, Koželj G, Stožer A, Drobnič M. The Influence of a Single Intra-Articular Lidocaine Injection on the Viability of Articular Cartilage in the Knee. Cartilage 2021; 13:456S-463S. [PMID: 32028796 PMCID: PMC8808909 DOI: 10.1177/1947603520904759] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
OBJECTIVE To evaluate the in vivo effect of a single intra-articular injection of local anesthetic (LA) lidocaine on the viability of articular cartilage in the intact or osteoarthritic (OA) human knees, and to measure the synovial postinjection concentration of lidocaine in the knee. DESIGN This study includes 3 interconnected experiments: (A) Synovial LA concentration measurement after a 2% lidocaine injection before knee arthroscopy in 10 patients by liquid chromatography-tandem mass spectrometry (LC-MS/MS). (B) Human osteochondral explants (N = 27) from intact knees procured at autopsies were incubated for different time intervals (30 minutes, 2 hours, 24 hours) with 2% lidocaine, 0.04% lidocaine (measured), or culture medium (control), and later evaluated for cell viability by LIVE/DEAD staining. (C) Ten out of 19 matched patients scheduled for knee replacement received a single intra-articular injection of 2% lidocaine approximately 30 minutes prior to the procedure; 9 patients served as control. Osteochondral samples with OA changes were harvested during surgery and analyzed for chondrocyte viability by LIVE/DEAD staining. RESULTS (A) The synovial LA concentration was significantly lower than the primary concentration injected: average 0.23 mg/mL (0.02%), highest measured 0.37 mg/mL (0.04%). (B) In vitro exposure to a reduced LA concentration had no significant influence on chondrocyte viability in intact cartilage explants (24-hour averages: control, 93%; 0.04% lidocaine, 92%; 2% lidocaine, 79%). (C) Viability of chondrocytes in OA knees was similar between 2% lidocaine injection (85%) and control (80%). CONCLUSIONS A single intra-articular knee injection of 2% lidocaine did not influence the chondrocyte viability neither in healthy nor in OA cartilage. A fast postinjection reduction of synovial LA concentration (more than 40 times) is the most likely protective mechanism.
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Affiliation(s)
- Klemen Ravnihar
- Valdoltra Orthopaedic Hospital, Ankaran,
Slovenia,Klemen Ravnihar, Valdoltra Orthopaedic
Hospital, Jadranska cesta 31, Ankaran, SI-6280, Slovenia.
| | - Tomaž Marš
- Institute for Pathophysiology, Faculty
of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Sergej Pirkmajer
- Institute for Pathophysiology, Faculty
of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Armin Alibegović
- Institute of Forensic Medicine, Faculty
of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Gordana Koželj
- Department of Toxicology, Institute of
Forensic Medicine, Faculty of Medicine, University of Ljubljana, Ljubljana,
Slovenia
| | - Andraž Stožer
- Institute of Physiology, Medical
Faculty, University of Maribor, Maribor, Slovenia
| | - Matej Drobnič
- Department of Orthopedic Surgery,
University Medical Centre Ljubljana, Ljubljana, Slovenia
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13
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Petrič M, Vidović A, Dolinar K, Miš K, Chibalin AV, Pirkmajer S. Phosphorylation of Na +,K +-ATPase at Tyr10 of the α1-Subunit is Suppressed by AMPK and Enhanced by Ouabain in Cultured Kidney Cells. J Membr Biol 2021; 254:531-548. [PMID: 34748042 PMCID: PMC8595181 DOI: 10.1007/s00232-021-00209-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 10/27/2021] [Indexed: 01/03/2023]
Abstract
Na+,K+-ATPase (NKA) is essential for maintenance of cellular and whole-body water and ion homeostasis. In the kidney, a major site of ion transport, NKA consumes ~ 50% of ATP, indicating a tight coordination of NKA and energy metabolism. AMP-activated protein kinase (AMPK), a cellular energy sensor, regulates NKA by modulating serine phosphorylation of the α1-subunit, but whether it modulates other important regulatory phosphosites, such as Tyr10, is unknown. Using human kidney (HK-2) cells, we determined that the phosphorylation of Tyr10 was stimulated by the epidermal growth factor (EGF), which was opposed by inhibitors of Src kinases (PP2), tyrosine kinases (genistein), and EGF receptor (EGFR, gefitinib). AMPK activators AICAR and A-769662 suppressed the EGF-stimulated phosphorylation of EGFR (Tyr1173) and NKAα1 at Tyr10. The phosphorylation of Src (Tyr416) was unaltered by AICAR and increased by A-769662. Conversely, ouabain (100 nM), a pharmacological NKA inhibitor and a putative adrenocortical hormone, enhanced the EGF-stimulated Tyr10 phosphorylation without altering the phosphorylation of EGFR (Tyr1173) or Src (Tyr416). Ouabain (100–1000 nM) increased the ADP:ATP ratio, while it suppressed the lactate production and the oxygen consumption rate in a dose-dependent manner. Treatment with ouabain or gene silencing of NKAα1 or NKAα3 subunit did not activate AMPK. In summary, AMPK activators and ouabain had antagonistic effects on the phosphorylation of NKAα1 at Tyr10 in cultured HK-2 cells, which implicates a role for Tyr10 in coordinated regulation of NKA-mediated ion transport and energy metabolism.
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Affiliation(s)
- Metka Petrič
- Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia
| | - Anja Vidović
- Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia
| | - Klemen Dolinar
- Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia
| | - Katarina Miš
- Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia
| | - Alexander V Chibalin
- National Research Tomsk State University, Tomsk, Russia. .,Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden.
| | - Sergej Pirkmajer
- Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia.
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14
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Zandona A, Maraković N, Mišetić P, Madunić J, Miš K, Padovan J, Pirkmajer S, Katalinić M. Activation of (un)regulated cell death as a new perspective for bispyridinium and imidazolium oximes. Arch Toxicol 2021; 95:2737-2754. [PMID: 34173857 DOI: 10.1007/s00204-021-03098-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 06/15/2021] [Indexed: 12/20/2022]
Abstract
Oximes, investigated as antidotes against organophosphates (OP) poisoning, are known to display toxic effects on a cellular level, which could be explained beyond action on acetylcholinesterase as their main target. To investigate this further, we performed an in vitro cell-based evaluation of effects of two structurally diverse oxime groups at concentrations of up to 800 μM, on several cell models: skeletal muscle, kidney, liver, and neural cells. As indicated by our results, compounds with an imidazolium core induced necrosis, unregulated cell death characterized by a cell burst, increased formation of reactive oxygen species, and activation of antioxidant scavenging. On the other hand, oximes with a pyridinium core activated apoptosis through specific caspases 3, 8, and/or 9. Interestingly, some of the compounds exhibited a synergistic effect. Moreover, we generated a pharmacophore model for each oxime series and identified ligands from public databases that map to generated pharmacophores. Several interesting hits were obtained including chemotherapeutics and specific inhibitors. We were able to define the possible structural features of tested oximes triggering toxic effects: chlorine atoms in combination with but-2(E)-en-1,4-diyl linker and adding a second benzene ring with substituents such as chlorine and/or methyl on the imidazolium core. Such oximes could not be used in further OP antidote development research, but could be introduced in other research studies on new specific targets. This could undoubtedly result in an overall improved wider use of unexplored oxime database created so far in OP antidotes field of research in a completely new perspective.
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Affiliation(s)
- Antonio Zandona
- Institute for Medical Research and Occupational Health, POB 291, 10001, Zagreb, Croatia
| | - Nikola Maraković
- Institute for Medical Research and Occupational Health, POB 291, 10001, Zagreb, Croatia
| | | | - Josip Madunić
- Institute for Medical Research and Occupational Health, POB 291, 10001, Zagreb, Croatia
| | - Katarina Miš
- Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia
| | | | - Sergej Pirkmajer
- Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia
| | - Maja Katalinić
- Institute for Medical Research and Occupational Health, POB 291, 10001, Zagreb, Croatia.
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15
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Kacin A, Drobnič M, Marš T, Miš K, Petrič M, Weber D, Tomc Žargi T, Martinčič D, Pirkmajer S. Functional and molecular adaptations of quadriceps and hamstring muscles to blood flow restricted training in patients with ACL rupture. Scand J Med Sci Sports 2021; 31:1636-1646. [PMID: 33837592 DOI: 10.1111/sms.13968] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 03/01/2021] [Accepted: 03/26/2021] [Indexed: 12/21/2022]
Abstract
Effects of low-load blood flow restricted (LL-BFR) training remain unexplored in patients with ACL rupture. Our hypothesis was that LL-BFR training triggers augmented gains in knee muscle strength and size, which are paralleled with transcriptional responses of hypoxia-regulated genes and myokines. Eighteen volunteers (age 37.5 ± 9 years) planned for ACL reconstruction, participated in the study. Twelve were divided between BFR group, performing 9 sessions of LL-BFR exercise, and SHAM-BFR group performing equal training with sham vascular occlusion. Six subjects served as a control for muscle biopsy analysis. Cross-sectional area (CSA) and isokinetic strength of knee muscles were assessed before and after the training. Change in CSAquad was significantly (p < 0.01) larger in BFR (4.9%) compared with SHAM-BFR (1.3%). Similarly, change in peak torque of knee extensors was significantly (p < 0.05) larger in BFR (14%) compared with SHAM-BFR (-1%). The decrease in fatigue index of knee extensors (6%) was larger (p < 0.01) in BFR than in SHAM-BFR (2%). mRNA expression of HIF-1α in the vastus lateralis was reduced (p < 0.05) in SHAM-BFR, while VEGF-A mRNA tended to be higher in BFR. The mRNA expression of myostatin and its receptor were reduced (p < 0.05) in the semitendinosus after both types of training. Expression of IL-6, its receptors IL-6Rα and gp130, as well as musclin were similar in control and training groups. In conclusion, our results show augmented strength and endurance of knee extensors but less of the flexors. LL-BFR training is especially effective for conditioning of knee extensors in this population.
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Affiliation(s)
- Alan Kacin
- Department of Physiotherapy, Faculty of Health Sciences, University of Ljubljana, Ljubljana, Slovenia.,Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Matej Drobnič
- Department of Orthopedic Surgery, University Medical Centre Ljubljana, Ljubljana, Slovenia.,Chair of Orthopedics, Medical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Tomaž Marš
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Katarina Miš
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Maja Petrič
- Department of Physiotherapy, Faculty of Health Sciences, University of Ljubljana, Ljubljana, Slovenia
| | - Daša Weber
- Department of Physiotherapy, Faculty of Health Sciences, University of Ljubljana, Ljubljana, Slovenia
| | - Tina Tomc Žargi
- Department of Physiotherapy, Faculty of Health Sciences, University of Ljubljana, Ljubljana, Slovenia
| | - David Martinčič
- Department of Orthopedic Surgery, University Medical Centre Ljubljana, Ljubljana, Slovenia.,Chair of Orthopedics, Medical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
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16
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Marš T, Miš K, Meznarič M, Prpar Mihevc S, Jan V, Haugen F, Rogelj B, Rustan AC, Thoresen GH, Pirkmajer S, Nikolić N. Innervation and electrical pulse stimulation — in vitro effects on human skeletal muscle cells. Appl Physiol Nutr Metab 2021; 46:299-308. [DOI: 10.1139/apnm-2019-0575] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Contraction-induced adaptations in skeletal muscles are well characterized in vivo, but the underlying cellular mechanisms are still not completely understood. Cultured human myotubes represent an essential model system for human skeletal muscle that can be modulated ex vivo, but they are quiescent and do not contract unless being stimulated. Stimulation can be achieved by innervation of human myotubes in vitro by co-culturing with embryonic rat spinal cord, or by replacing motor neuron activation by electrical pulse stimulation (EPS). Effects of these two in vitro approaches, innervation and EPS, were characterized with respects to the expression of myosin heavy chains (MyHCs) and metabolism of glucose and oleic acid in cultured human myotubes. Adherent human myotubes were either innervated with rat spinal cord segments or exposed to EPS. The expression pattern of MyHCs was assessed by quantitative polymerase chain reaction, immunoblotting, and immunofluorescence, while the metabolism of glucose and oleic acid were studied using radiolabelled substrates. Innervation and EPS promoted differentiation towards different fiber types in human myotubes. Expression of the slow MyHC-1 isoform was reduced in innervated myotubes, whereas it remained unaltered in EPS-treated cells. Expression of both fast isoforms (MyHC-2A and MyHC-2X) tended to decrease in EPS-treated cells. Both approaches induced a more oxidative phenotype, reflected in increased CO2 production from both glucose and oleic acid. Novelty: Innervation and EPS favour differentiation into different fiber types in human myotubes. Both innervation and EPS promote a metabolically more oxidative phenotype in human myotubes.
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Affiliation(s)
- Tomaz Marš
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Slovenia
| | - Katarina Miš
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Slovenia
| | - Marija Meznarič
- Institute of Anatomy, Faculty of Medicine, University of Ljubljana, Slovenia
| | - Sonja Prpar Mihevc
- Department of Biotechnology, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Vid Jan
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Slovenia
| | - Fred Haugen
- Department of Work Psychology and Physiology, STAMI - The National Institute of Occupational Health, Oslo, Norway
| | - Boris Rogelj
- Department of Biotechnology, Jožef Stefan Institute, Ljubljana, Slovenia
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana, Slovenia
- Biomedical Research Institute (BRIS), Ljubljana, Slovenia
| | - Arild C. Rustan
- Department of Pharmacy, Section for Pharmacology and Pharmaceutical Biosciences, University of Oslo, Norway
| | - G. Hege Thoresen
- Department of Pharmacy, Section for Pharmacology and Pharmaceutical Biosciences, University of Oslo, Norway
- Department of Pharmacology, Institute of Clinical Medicine, University of Oslo, Norway
| | - Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Slovenia
| | - Nataša Nikolić
- Department of Pharmacy, Section for Pharmacology and Pharmaceutical Biosciences, University of Oslo, Norway
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17
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Jan V, Miš K, Nikolic N, Dolinar K, Petrič M, Bone A, Thoresen GH, Rustan AC, Marš T, Chibalin AV, Pirkmajer S. Effect of differentiation, de novo innervation, and electrical pulse stimulation on mRNA and protein expression of Na+,K+-ATPase, FXYD1, and FXYD5 in cultured human skeletal muscle cells. PLoS One 2021; 16:e0247377. [PMID: 33635930 PMCID: PMC7909653 DOI: 10.1371/journal.pone.0247377] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Accepted: 02/05/2021] [Indexed: 12/18/2022] Open
Abstract
Denervation reduces the abundance of Na+,K+-ATPase (NKA) in skeletal muscle, while reinnervation increases it. Primary human skeletal muscle cells, the most widely used model to study human skeletal muscle in vitro, are usually cultured as myoblasts or myotubes without neurons and typically do not contract spontaneously, which might affect their ability to express and regulate NKA. We determined how differentiation, de novo innervation, and electrical pulse stimulation affect expression of NKA (α and β) subunits and NKA regulators FXYD1 (phospholemman) and FXYD5 (dysadherin). Differentiation of myoblasts into myotubes under low serum conditions increased expression of myogenic markers CD56 (NCAM1), desmin, myosin heavy chains, dihydropyridine receptor subunit α1S, and SERCA2 as well as NKAα2 and FXYD1, while it decreased expression of FXYD5 mRNA. Myotubes, which were innervated de novo by motor neurons in co-culture with the embryonic rat spinal cord explants, started to contract spontaneously within 7–10 days. A short-term co-culture (10–11 days) promoted mRNA expression of myokines, such as IL-6, IL-7, IL-8, and IL-15, but did not affect mRNA expression of NKA, FXYDs, or myokines, such as musclin, cathepsin B, meteorin-like protein, or SPARC. A long-term co-culture (21 days) increased the protein abundance of NKAα1, NKAα2, FXYD1, and phospho-FXYD1Ser68 without attendant changes in mRNA levels. Suppression of neuromuscular transmission with α-bungarotoxin or tubocurarine for 24 h did not alter NKA or FXYD mRNA expression. Electrical pulse stimulation (48 h) of non-innervated myotubes promoted mRNA expression of NKAβ2, NKAβ3, FXYD1, and FXYD5. In conclusion, low serum concentration promotes NKAα2 and FXYD1 expression, while de novo innervation is not essential for upregulation of NKAα2 and FXYD1 mRNA in cultured myotubes. Finally, although innervation and EPS both stimulate contractions of myotubes, they exert distinct effects on the expression of NKA and FXYDs.
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Affiliation(s)
- Vid Jan
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Katarina Miš
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Natasa Nikolic
- Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, Oslo, Norway
| | - Klemen Dolinar
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Metka Petrič
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Andraž Bone
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - G. Hege Thoresen
- Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, Oslo, Norway
- Department of Pharmacology, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Arild C. Rustan
- Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, Oslo, Norway
| | - Tomaž Marš
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Alexander V. Chibalin
- National Research Tomsk State University, Tomsk, Russia
- Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
- * E-mail:
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18
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Skočaj M, Bizjak M, Strojan K, Lojk J, Erdani Kreft M, Miš K, Pirkmajer S, Bregar VB, Veranič P, Pavlin M. Proposing Urothelial and Muscle In Vitro Cell Models as a Novel Approach for Assessment of Long-Term Toxicity of Nanoparticles. Int J Mol Sci 2020; 21:ijms21207545. [PMID: 33066271 PMCID: PMC7589566 DOI: 10.3390/ijms21207545] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 10/07/2020] [Accepted: 10/09/2020] [Indexed: 12/11/2022] Open
Abstract
Many studies evaluated the short-term in vitro toxicity of nanoparticles (NPs); however, long-term effects are still not adequately understood. Here, we investigated the potential toxic effects of biomedical (polyacrylic acid and polyethylenimine coated magnetic NPs) and two industrial (SiO2 and TiO2) NPs following different short-term and long-term exposure protocols on two physiologically different in vitro models that are able to differentiate: L6 rat skeletal muscle cell line and biomimetic normal porcine urothelial (NPU) cells. We show that L6 cells are more sensitive to NP exposure then NPU cells. Transmission electron microscopy revealed an uptake of NPs into L6 cells but not NPU cells. In L6 cells, we obtained a dose-dependent reduction in cell viability and increased reactive oxygen species (ROS) formation after 24 h. Following continuous exposure, more stable TiO2 and polyacrylic acid (PAA) NPs increased levels of nuclear factor Nrf2 mRNA, suggesting an oxidative damage-associated response. Furthermore, internalized magnetic PAA and TiO2 NPs hindered the differentiation of L6 cells. We propose the use of L6 skeletal muscle cells and NPU cells as a novel approach for assessment of the potential long-term toxicity of relevant NPs that are found in the blood and/or can be secreted into the urine.
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Affiliation(s)
- Matej Skočaj
- Group for nano and biotechnological applications, Faculty of Electrical Engineering, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (M.S.); (M.B.); (K.S.); (J.L.); (V.B.B.)
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (K.M.); (S.P.)
- Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, SI-1000 Ljubljana, Slovenia;
| | - Maruša Bizjak
- Group for nano and biotechnological applications, Faculty of Electrical Engineering, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (M.S.); (M.B.); (K.S.); (J.L.); (V.B.B.)
- Institute of Biophysics, Faculty of Medicine, University of Ljubljana, SI-1000 Ljubljana, Slovenia
| | - Klemen Strojan
- Group for nano and biotechnological applications, Faculty of Electrical Engineering, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (M.S.); (M.B.); (K.S.); (J.L.); (V.B.B.)
| | - Jasna Lojk
- Group for nano and biotechnological applications, Faculty of Electrical Engineering, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (M.S.); (M.B.); (K.S.); (J.L.); (V.B.B.)
- Institute of Biophysics, Faculty of Medicine, University of Ljubljana, SI-1000 Ljubljana, Slovenia
| | - Mateja Erdani Kreft
- Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, SI-1000 Ljubljana, Slovenia;
| | - Katarina Miš
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (K.M.); (S.P.)
| | - Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (K.M.); (S.P.)
| | - Vladimir Boštjan Bregar
- Group for nano and biotechnological applications, Faculty of Electrical Engineering, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (M.S.); (M.B.); (K.S.); (J.L.); (V.B.B.)
| | - Peter Veranič
- Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, SI-1000 Ljubljana, Slovenia;
- Correspondence: (P.V.); (M.P.)
| | - Mojca Pavlin
- Group for nano and biotechnological applications, Faculty of Electrical Engineering, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (M.S.); (M.B.); (K.S.); (J.L.); (V.B.B.)
- Institute of Biophysics, Faculty of Medicine, University of Ljubljana, SI-1000 Ljubljana, Slovenia
- Correspondence: (P.V.); (M.P.)
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Pirkmajer S, Bezjak K, Matkovič U, Dolinar K, Jiang LQ, Miš K, Gros K, Milovanova K, Pirkmajer KP, Marš T, Kapilevich L, Chibalin AV. Ouabain Suppresses IL-6/STAT3 Signaling and Promotes Cytokine Secretion in Cultured Skeletal Muscle Cells. Front Physiol 2020; 11:566584. [PMID: 33101052 PMCID: PMC7544989 DOI: 10.3389/fphys.2020.566584] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 08/25/2020] [Indexed: 12/16/2022] Open
Abstract
The cardiotonic steroids (CTS), such as ouabain and marinobufagenin, are thought to be adrenocortical hormones secreted during exercise and the stress response. The catalytic α-subunit of Na,K-ATPase (NKA) is a CTS receptor, whose largest pool is located in skeletal muscles, indicating that muscles are a major target for CTS. Skeletal muscles contribute to adaptations to exercise by secreting interleukin-6 (IL-6) and plethora of other cytokines, which exert paracrine and endocrine effects in muscles and non-muscle tissues. Here, we determined whether ouabain, a prototypical CTS, modulates IL-6 signaling and secretion in the cultured human skeletal muscle cells. Ouabain (2.5–50 nM) suppressed the abundance of STAT3, a key transcription factor downstream of the IL-6 receptor, as well as its basal and IL-6-stimulated phosphorylation. Conversely, ouabain (50 nM) increased the phosphorylation of ERK1/2, Akt, p70S6K, and S6 ribosomal protein, indicating activation of the ERK1/2 and the Akt-mTOR pathways. Proteasome inhibitor MG-132 blocked the ouabain-induced suppression of the total STAT3, but did not prevent the dephosphorylation of STAT3. Ouabain (50 nM) suppressed hypoxia-inducible factor-1α (HIF-1α), a modulator of STAT3 signaling, but gene silencing of HIF-1α and/or its partner protein HIF-1β did not mimic effects of ouabain on the phosphorylation of STAT3. Ouabain (50 nM) failed to suppress the phosphorylation of STAT3 and HIF-1α in rat L6 skeletal muscle cells, which express the ouabain-resistant α1-subunit of NKA. We also found that ouabain (100 nM) promoted the secretion of IL-6, IL-8, GM-CSF, and TNF-α from the skeletal muscle cells of healthy subjects, and the secretion of GM-CSF from cells of subjects with the type 2 diabetes. Marinobufagenin (10 nM), another important CTS, did not alter the secretion of these cytokines. In conclusion, our study shows that ouabain suppresses the IL-6 signaling via STAT3, but promotes the secretion of IL-6 and other cytokines, which might represent a negative feedback in the IL-6/STAT3 pathway. Collectively, our results implicate a role for CTS and NKA in regulation of the IL-6 signaling and secretion in skeletal muscle.
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Affiliation(s)
- Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Katja Bezjak
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Urška Matkovič
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Klemen Dolinar
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Lake Q Jiang
- Integrative Physiology, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Katarina Miš
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Katarina Gros
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Kseniya Milovanova
- Department of Sports and Health Tourism, Sports Physiology and Medicine, National Research Tomsk State University, Tomsk, Russia
| | - Katja Perdan Pirkmajer
- Department of Rheumatology, University Medical Centre Ljubljana, Ljubljana, Slovenia.,Department of Internal Medicine, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Tomaž Marš
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Leonid Kapilevich
- Department of Sports and Health Tourism, Sports Physiology and Medicine, National Research Tomsk State University, Tomsk, Russia.,Central Scientific Laboratory, Siberian State Medical University, Tomsk, Russia
| | - Alexander V Chibalin
- Integrative Physiology, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
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20
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Bizjak M, Malavašič P, Pirkmajer S, Pavlin M. Comparison of the effects of metformin on MDA-MB-231 breast cancer cells in a monolayer culture and in tumor spheroids as a function of nutrient concentrations. Biochem Biophys Res Commun 2019; 515:296-302. [PMID: 31146913 DOI: 10.1016/j.bbrc.2019.05.090] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 05/12/2019] [Indexed: 01/06/2023]
Abstract
Metabolic pathways of cancer cells depend on the concentrations of nutrients in their micro-environment as well as on the cell-to-cell interactions. Here we examined the effects of glucose, pyruvate and glutamine on the sensitivity of MDA-MB-231 cells to metabolic drug metformin using standard 2D culture, in which cells are grown in a monolayer, and 3D tumor spheroids, in which three-dimensional growth of cells better mimics a tumor. To examine effects of nutrients on metformin action, MDA-MB-231 cells were grown in commonly used media (DMEM, MEM and RPMI-1640) that differ mainly in the concentrations of amino acids. We used MTS assay and Hoechst and propidium iodide staining to determine cell number, viability and survival, respectively. We also determined the size of tumor spheroids and assessed effects of nutrients on metformin-stimulated AMP-activated protein kinase activation. Non-essential amino acids suppressed the effects of metformin on MDA-MB-231 cells in a 2D culture and in 3D tumor spheroids. Glutamine and pyruvate weakly diminished the effects of metformin in 2D culture. Furthermore, glucose protected tumor spheroids against metformin-induced disintegration. Our results show that nutrient availability must be considered when we evaluate the effects of metformin in 2D culture and in biologically more relevant 3D tumor spheroids.
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Affiliation(s)
- Maruša Bizjak
- Group for Nano and Biotechnological Applications, Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia; Institute of Biophysics, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.
| | - Petra Malavašič
- Group for Nano and Biotechnological Applications, Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia.
| | - Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.
| | - Mojca Pavlin
- Group for Nano and Biotechnological Applications, Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia; Institute of Biophysics, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.
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21
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Dolinar K, Jan V, Pavlin M, Chibalin AV, Pirkmajer S. Nucleosides block AICAR-stimulated activation of AMPK in skeletal muscle and cancer cells. Am J Physiol Cell Physiol 2018; 315:C803-C817. [PMID: 30230919 DOI: 10.1152/ajpcell.00311.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
AMP-activated kinase (AMPK) is a major regulator of energy metabolism and a promising target for development of new treatments for type 2 diabetes and cancer. 5-Aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR), an adenosine analog, is a standard positive control for AMPK activation in cell-based assays. Some broadly used cell culture media, such as minimal essential medium α (MEMα), contain high concentrations of adenosine and other nucleosides. We determined whether such media alter AICAR action in skeletal muscle and cancer cells. In nucleoside-free media, AICAR stimulated AMPK activation, increased glucose uptake, and suppressed cell proliferation. Conversely, these effects were blunted or completely blocked in MEMα that contains nucleosides. Addition of adenosine or 2'-deoxyadenosine to nucleoside-free media also suppressed AICAR action. MEMα with nucleosides blocked AICAR-stimulated AMPK activation even in the presence of methotrexate, which normally markedly enhances AICAR action by reducing its intracellular clearance. Other common media components, such as vitamin B-12, vitamin C, and α-lipoic acid, had a minor modulatory effect on AICAR action. Our findings show that nucleoside-containing media, commonly used in AMPK research, block action of the most widely used pharmacological AMPK activator AICAR. Results of cell-based assays in which AICAR is used for AMPK activation therefore critically depend on media formulation. Furthermore, our findings highlight a role for extracellular nucleosides and nucleoside transporters in regulation of AMPK activation.
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Affiliation(s)
- Klemen Dolinar
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana , Ljubljana , Slovenia.,Group for Nano and Biotechnological Applications, Faculty of Electrical Engineering, University of Ljubljana , Ljubljana , Slovenia
| | - Vid Jan
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana , Ljubljana , Slovenia
| | - Mojca Pavlin
- Group for Nano and Biotechnological Applications, Faculty of Electrical Engineering, University of Ljubljana , Ljubljana , Slovenia.,Institute of Biophysics, Faculty of Medicine, University of Ljubljana , Ljubljana , Slovenia
| | - Alexander V Chibalin
- Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet , Stockholm , Sweden.,National Research Tomsk State University , Tomsk , Russia
| | - Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana , Ljubljana , Slovenia
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22
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Vardjan N, Chowdhury HH, Horvat A, Velebit J, Malnar M, Muhič M, Kreft M, Krivec ŠG, Bobnar ST, Miš K, Pirkmajer S, Offermanns S, Henriksen G, Storm-Mathisen J, Bergersen LH, Zorec R. Enhancement of Astroglial Aerobic Glycolysis by Extracellular Lactate-Mediated Increase in cAMP. Front Mol Neurosci 2018; 11:148. [PMID: 29867342 PMCID: PMC5953330 DOI: 10.3389/fnmol.2018.00148] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 04/16/2018] [Indexed: 11/13/2022] Open
Abstract
Besides being a neuronal fuel, L-lactate is also a signal in the brain. Whether extracellular L-lactate affects brain metabolism, in particular astrocytes, abundant neuroglial cells, which produce L-lactate in aerobic glycolysis, is unclear. Recent studies suggested that astrocytes express low levels of the L-lactate GPR81 receptor (EC50 ≈ 5 mM) that is in fat cells part of an autocrine loop, in which the Gi-protein mediates reduction of cytosolic cyclic adenosine monophosphate (cAMP). To study whether a similar signaling loop is present in astrocytes, affecting aerobic glycolysis, we measured the cytosolic levels of cAMP, D-glucose and L-lactate in single astrocytes using fluorescence resonance energy transfer (FRET)-based nanosensors. In contrast to the situation in fat cells, stimulation by extracellular L-lactate and the selective GPR81 agonists, 3-chloro-5-hydroxybenzoic acid (3Cl-5OH-BA) or 4-methyl-N-(5-(2-(4-methylpiperazin-1-yl)-2-oxoethyl)-4-(2-thienyl)-1,3-thiazol-2-yl)cyclohexanecarboxamide (Compound 2), like adrenergic stimulation, elevated intracellular cAMP and L-lactate in astrocytes, which was reduced by the inhibition of adenylate cyclase. Surprisingly, 3Cl-5OH-BA and Compound 2 increased cytosolic cAMP also in GPR81-knock out astrocytes, indicating that the effect is GPR81-independent and mediated by a novel, yet unidentified, excitatory L-lactate receptor-like mechanism in astrocytes that enhances aerobic glycolysis and L-lactate production via a positive feedback mechanism.
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Affiliation(s)
- Nina Vardjan
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.,Laboratory of Cell Engineering, Celica Biomedical, Ljubljana, Slovenia
| | - Helena H Chowdhury
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.,Laboratory of Cell Engineering, Celica Biomedical, Ljubljana, Slovenia
| | - Anemari Horvat
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Jelena Velebit
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.,Laboratory of Cell Engineering, Celica Biomedical, Ljubljana, Slovenia
| | - Maja Malnar
- Laboratory of Cell Engineering, Celica Biomedical, Ljubljana, Slovenia
| | - Marko Muhič
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Marko Kreft
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.,Laboratory of Cell Engineering, Celica Biomedical, Ljubljana, Slovenia.,Department of Biology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Špela G Krivec
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.,Laboratory of Cell Engineering, Celica Biomedical, Ljubljana, Slovenia
| | - Saša T Bobnar
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.,Laboratory of Cell Engineering, Celica Biomedical, Ljubljana, Slovenia
| | - Katarina Miš
- Laboratory for Molecular Neurobiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Sergej Pirkmajer
- Laboratory for Molecular Neurobiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Stefan Offermanns
- Department of Pharmacology, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Gjermund Henriksen
- Nuclear and Energy Physics, Department of Physics, The Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo, Norway.,Norwegian Medical Cyclotron Centre Ltd., Oslo, Norway
| | - Jon Storm-Mathisen
- Division of Anatomy, Department of Molecular Medicine, CMBN/SERTA Healthy Brain Ageing Centre, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Linda H Bergersen
- Institute of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway.,Center for Healthy Aging, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Robert Zorec
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.,Laboratory of Cell Engineering, Celica Biomedical, Ljubljana, Slovenia
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Kovač P, Miš K, Pirkmajer S, Marš T, Klokočovnik T, Kotnik G, Podbregar E, Podbregar M. How to Measure Tissue Oxygenation Using Near-Infrared Spectroscopy in a Patient With Alkaptonuria. J Cardiothorac Vasc Anesth 2018; 32:2708-2711. [PMID: 29459112 DOI: 10.1053/j.jvca.2018.01.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Indexed: 11/11/2022]
Affiliation(s)
- Petra Kovač
- Clinical Department for Anesthesiology and Surgical Intensive Care Unit, University Medical Centre Ljubljana, Ljubljana, Slovenia
| | - Katarina Miš
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Tomaž Marš
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Tomislav Klokočovnik
- Clinical Department for Cardiovascular Surgery, University Medical Centre Ljubljana, Ljubljana, Slovenia
| | - Gloria Kotnik
- Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Eva Podbregar
- Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Matej Podbregar
- Clinical Department for Anesthesiology and Surgical Intensive Care Unit, University Medical Centre Ljubljana, Ljubljana, Slovenia; Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.
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24
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Mis K, Grubic Z, Lorenzon P, Sciancalepore M, Mars T, Pirkmajer S. In Vitro Innervation as an Experimental Model to Study the Expression and Functions of Acetylcholinesterase and Agrin in Human Skeletal Muscle. Molecules 2017; 22:molecules22091418. [PMID: 28846617 PMCID: PMC6151842 DOI: 10.3390/molecules22091418] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 08/18/2017] [Accepted: 08/23/2017] [Indexed: 12/19/2022] Open
Abstract
Acetylcholinesterase (AChE) and agrin, a heparan-sulfate proteoglycan, reside in the basal lamina of the neuromuscular junction (NMJ) and play key roles in cholinergic transmission and synaptogenesis. Unlike most NMJ components, AChE and agrin are expressed in skeletal muscle and α-motor neurons. AChE and agrin are also expressed in various other types of cells, where they have important alternative functions that are not related to their classical roles in NMJ. In this review, we first focus on co-cultures of embryonic rat spinal cord explants with human skeletal muscle cells as an experimental model to study functional innervation in vitro. We describe how this heterologous rat-human model, which enables experimentation on highly developed contracting human myotubes, offers unique opportunities for AChE and agrin research. We then highlight innovative approaches that were used to address salient questions regarding expression and alternative functions of AChE and agrin in developing human skeletal muscle. Results obtained in co-cultures are compared with those obtained in other models in the context of general advances in the field of AChE and agrin neurobiology.
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Affiliation(s)
- Katarina Mis
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, SI-1000 Ljubljana, Slovenia.
| | - Zoran Grubic
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, SI-1000 Ljubljana, Slovenia.
| | - Paola Lorenzon
- Department of Life Sciences, University of Trieste, via A. Fleming 22, I-34127 Trieste, Italy.
| | - Marina Sciancalepore
- Department of Life Sciences, University of Trieste, via A. Fleming 22, I-34127 Trieste, Italy.
| | - Tomaz Mars
- Department of Life Sciences, University of Trieste, via A. Fleming 22, I-34127 Trieste, Italy.
| | - Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, SI-1000 Ljubljana, Slovenia.
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25
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Pirkmajer S, Kirchner H, Lundell LS, Zelenin PV, Zierath JR, Makarova KS, Wolf YI, Chibalin AV. Early vertebrate origin and diversification of small transmembrane regulators of cellular ion transport. J Physiol 2017; 595:4611-4630. [PMID: 28436536 DOI: 10.1113/jp274254] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 04/19/2017] [Indexed: 12/31/2022] Open
Abstract
KEY POINTS Small transmembrane proteins such as FXYDs, which interact with Na+ ,K+ -ATPase, and the micropeptides that interact with sarco/endoplasmic reticulum Ca2+ -ATPase play fundamental roles in regulation of ion transport in vertebrates. Uncertain evolutionary origins and phylogenetic relationships among these regulators of ion transport have led to inconsistencies in their classification across vertebrate species, thus hampering comparative studies of their functions. We discovered the first FXYD homologue in sea lamprey, a basal jawless vertebrate, which suggests small transmembrane regulators of ion transport emerged early in the vertebrate lineage. We also identified 13 gene subfamilies of FXYDs and propose a revised, phylogeny-based FXYD classification that is consistent across vertebrate species. These findings provide an improved framework for investigating physiological and pathophysiological functions of small transmembrane regulators of ion transport. ABSTRACT Small transmembrane proteins are important for regulation of cellular ion transport. The most prominent among these are members of the FXYD family (FXYD1-12), which regulate Na+ ,K+ -ATPase, and phospholamban, sarcolipin, myoregulin and DWORF, which regulate the sarco/endoplasmic reticulum Ca2+ -ATPase (SERCA). FXYDs and regulators of SERCA are present in fishes, as well as terrestrial vertebrates; however, their evolutionary origins and phylogenetic relationships are obscure, thus hampering comparative physiological studies. Here we discovered that sea lamprey (Petromyzon marinus), a representative of extant jawless vertebrates (Cyclostomata), expresses an FXYD homologue, which strongly suggests that FXYDs predate the emergence of fishes and other jawed vertebrates (Gnathostomata). Using a combination of sequence-based phylogenetic analysis and conservation of local chromosome context, we determined that FXYDs markedly diversified in the lineages leading to cartilaginous fishes (Chondrichthyes) and bony vertebrates (Euteleostomi). Diversification of SERCA regulators was much less extensive, indicating they operate under different evolutionary constraints. Finally, we found that FXYDs in extant vertebrates can be classified into 13 gene subfamilies, which do not always correspond to the established FXYD classification. We therefore propose a revised classification that is based on evolutionary history of FXYDs and that is consistent across vertebrate species. Collectively, our findings provide an improved framework for investigating the function of ion transport in health and disease.
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Affiliation(s)
- Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, SI-1000, Ljubljana, Slovenia
| | - Henriette Kirchner
- Department of Physiology and Pharmacology, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Leonidas S Lundell
- Department of Physiology and Pharmacology, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Pavel V Zelenin
- Department of Neuroscience, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Juleen R Zierath
- Department of Physiology and Pharmacology, Karolinska Institutet, SE-171 77, Stockholm, Sweden.,Department of Molecular Medicine and Surgery, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Kira S Makarova
- National Center for Biotechnology Information, NLM, National Institutes of Health, Bethesda, MD, 20894, USA
| | - Yuri I Wolf
- National Center for Biotechnology Information, NLM, National Institutes of Health, Bethesda, MD, 20894, USA
| | - Alexander V Chibalin
- Department of Molecular Medicine and Surgery, Karolinska Institutet, SE-171 77, Stockholm, Sweden
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26
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Bizjak M, Malavašič P, Dolinar K, Pohar J, Pirkmajer S, Pavlin M. Combined treatment with Metformin and 2-deoxy glucose induces detachment of viable MDA-MB-231 breast cancer cells in vitro. Sci Rep 2017; 7:1761. [PMID: 28496098 PMCID: PMC5431940 DOI: 10.1038/s41598-017-01801-5] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 04/04/2017] [Indexed: 12/13/2022] Open
Abstract
Triple naegative breast cancer has an increased rate of distant metastasis and consequently poor prognosis. To metastasize, breast cancer cells must detach from the main tumour mass and resist anoikis, a programmed cell death induced by lack of cell-extracellular matrix communication. Although cancer cells must detach to metastasize in vivo, the viability of floating cancer cells in vitro is rarely investigated. Here we show that co-treatment of anoikis-resistant MDA-MB-231 cells with metformin and 2-deoxy-D-glucose (2-DG) increased the percentage of floating cells, of which about 95% were viable. Floating cells resumed their proliferation once they were reseeded in the pharmacological compound-free medium. Similar effects on detachment were observed on anoikis-prone MCF-7 cells. Co-treatment of MDA-MB-231 cells with metformin and 2-DG induced a strong activation of AMP-activated protein kinase (AMPK), which was reduced by AMPK inhibitor compound C that prevented detachment of MDA-MB-231 cells. However, direct AMPK activators A-769662 and AICAR did not have any major effect on the percentage of floating MDA-MB-231 cells, indicating that AMPK activation is necessary but not sufficient for triggering detachment of cancer cells. Our results demonstrate that separate analysis of floating and attached cancer cells might be important for evaluation of anti-cancer agents.
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Affiliation(s)
- Maruša Bizjak
- Group for nano and biotechnological applications, Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Petra Malavašič
- Group for nano and biotechnological applications, Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Klemen Dolinar
- Group for nano and biotechnological applications, Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia.,Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Jelka Pohar
- Department of Synthetic Biology and Immunology, National institute of Chemistry, Ljubljana, Slovenia.,Centre of Excellence EN-FIST, Ljubljana, Slovenia
| | - Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Mojca Pavlin
- Group for nano and biotechnological applications, Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia. .,Institute of Biophysics, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.
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Lojk J, Strojan K, Miš K, Bregar BV, Hafner Bratkovič I, Bizjak M, Pirkmajer S, Pavlin M. Cell stress response to two different types of polymer coated cobalt ferrite nanoparticles. Toxicol Lett 2017; 270:108-118. [DOI: 10.1016/j.toxlet.2017.02.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 01/09/2017] [Accepted: 02/07/2017] [Indexed: 10/20/2022]
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Abstract
Skeletal muscle contains one of the largest and the most dynamic pools of Na,K-ATPase (NKA) in the body. Under resting conditions, NKA in skeletal muscle operates at only a fraction of maximal pumping capacity, but it can be markedly activated when demands for ion transport increase, such as during exercise or following food intake. Given the size, capacity, and dynamic range of the NKA pool in skeletal muscle, its tight regulation is essential to maintain whole body homeostasis as well as muscle function. To reconcile functional needs of systemic homeostasis with those of skeletal muscle, NKA is regulated in a coordinated manner by extrinsic stimuli, such as hormones and nerve-derived factors, as well as by local stimuli arising in skeletal muscle fibers, such as contractions and muscle energy status. These stimuli regulate NKA acutely by controlling its enzymatic activity and/or its distribution between the plasma membrane and the intracellular storage compartment. They also regulate NKA chronically by controlling NKA gene expression, thus determining total NKA content in skeletal muscle and its maximal pumping capacity. This review focuses on molecular mechanisms that underlie regulation of NKA in skeletal muscle by major extrinsic and local stimuli. Special emphasis is given to stimuli and mechanisms linking regulation of NKA and energy metabolism in skeletal muscle, such as insulin and the energy-sensing AMP-activated protein kinase. Finally, the recently uncovered roles for glutathionylation, nitric oxide, and extracellular K(+) in the regulation of NKA in skeletal muscle are highlighted.
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Affiliation(s)
- Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia; and
| | - Alexander V Chibalin
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
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Rajh M, Dolinar K, Miš K, Pavlin M, Pirkmajer S. Medium Renewal Blocks Anti-Proliferative Effects of Metformin in Cultured MDA-MB-231 Breast Cancer Cells. PLoS One 2016; 11:e0154747. [PMID: 27135408 PMCID: PMC4852933 DOI: 10.1371/journal.pone.0154747] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 04/18/2016] [Indexed: 12/13/2022] Open
Abstract
Epidemiological studies indicate that metformin, a widely used type 2 diabetes drug, might reduce breast cancer risk and mortality in patients with type 2 diabetes. Metformin might protect against breast cancer indirectly by ameliorating systemic glucose homeostasis. Alternatively, it might target breast cancer cells directly. However, experiments using MDA-MB-231 cells, a standard in vitro breast cancer model, produced inconsistent results regarding effectiveness of metformin as a direct anti-cancer agent. Metformin treatments in cultured MDA-MB-231 cells are usually performed for 48-96 hours, but protocols describing renewal of cell culture medium during these prolonged treatments are rarely reported. We determined whether medium renewal protocol might alter sensitivity of MDA-MB-231 cells treated with metformin. Using the MTS assay, BrdU incorporation and Hoechst staining we found that treatment with metformin for 48-72 hours failed to suppress viability and proliferation of MDA-MB-231 cells if low-glucose (1 g/L) medium was renewed every 24 hours. Conversely, metformin suppressed their viability and proliferation if medium was not renewed. Without renewal glucose concentration in the medium was reduced to 0.1 g/L in 72 hours, which likely explains increased sensitivity to metformin under these conditions. We also examined whether 2-deoxy-D-glucose (2-DG) reduces resistance to metformin. In the presence of 2-DG metformin reduced viability and proliferation of MDA-MB-231 cells with or without medium renewal, thus demonstrating that 2-DG reduces their resistance to metformin. In sum, we show that medium renewal blocks anti-proliferative effects of metformin during prolonged treatments in low-glucose medium. Differences in medium renewal protocols during prolonged treatments might therefore lead to apparently inconsistent results as regards effectiveness of metformin as a direct anti-cancer agent. Finally, our results indicate that co-therapy with 2-DG and metformin might provide an effective strategy to overcome metformin resistance of breast cancer cells.
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Affiliation(s)
- Maruša Rajh
- Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Klemen Dolinar
- Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Katarina Miš
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Mojca Pavlin
- Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
- * E-mail:
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Affiliation(s)
- S. Pirkmajer
- Institute of Pathophysiology; Faculty of Medicine; University of Ljubljana; Ljubljana Slovenia
| | - A. V. Chibalin
- Department of Molecular Medicine and Surgery; Karolinska Institutet; Stockholm Sweden
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Perdan-Pirkmajer K, Pirkmajer S, Thevis M, Thomas A, Praprotnik S, Hočevar A, Rotar Ž, Gašperšič N, Sodin-Šemrl S, Žibert J, Omersel J, Chibalin AV, Tomšič M, Ambrožič A. Methotrexate reduces HbA1c concentration but does not produce chronic accumulation of ZMP in patients with rheumatoid or psoriatic arthritis. Scand J Rheumatol 2016; 45:347-55. [PMID: 26726793 DOI: 10.3109/03009742.2015.1105290] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
OBJECTIVES The mechanism by which methotrexate (MTX) improves glucose homeostasis in patients with rheumatoid (RA) and psoriatic arthritis (PsA) remains undetermined. Animal studies indicate a role for intracellular accumulation of 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranosyl 5'-monophosphate (ZMP) but this has not been directly demonstrated in humans. We explored whether accumulation of ZMP is associated with improvements in glucose homeostasis during MTX therapy. METHOD MTX-naïve, non-diabetic RA (n = 16) and PsA (n = 10) patients received uninterrupted MTX treatment for 6 months. To evaluate whether ZMP accumulated during MTX therapy, we measured the concentration of ZMP in erythrocytes and the concentration of its dephosphorylated derivative 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR) in urine using liquid chromatography mass spectrometry (LC-MS/MS). To assess glucose homeostasis, we determined the concentration of glycated haemoglobin (HbA1c) and homeostasis model assessment of insulin resistance [HOMA-IR: fasting glucose (mmol/L) × fasting insulin (μU/mL)/22.5]. RESULTS Erythrocyte ZMP and urinary AICAR concentrations did not increase during 6 months of MTX therapy. HbA1c concentration was reduced from 5.80 ± 0.29% at baseline to 5.51 ± 0.32% at 6 months (p < 0.001), while HOMA-IR remained unaltered. Reduction in HbA1c concentration was not associated with increased ZMP or AICAR concentrations. CONCLUSIONS MTX therapy probably does not produce a chronic increase in erythrocyte ZMP or urinary AICAR concentrations. Collectively, our data do not support the hypothesis that MTX improves glucose homeostasis through chronic accumulation of ZMP.
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Affiliation(s)
- K Perdan-Pirkmajer
- a Department of Rheumatology , University Medical Centre Ljubljana , Slovenia
| | - S Pirkmajer
- b Institute of Pathophysiology, Faculty of Medicine , University of Ljubljana , Slovenia
| | - M Thevis
- c Institute of Biochemistry, Centre for Preventive Doping Research , German Sport University Cologne , Germany
| | - A Thomas
- c Institute of Biochemistry, Centre for Preventive Doping Research , German Sport University Cologne , Germany
| | - S Praprotnik
- a Department of Rheumatology , University Medical Centre Ljubljana , Slovenia
| | - A Hočevar
- a Department of Rheumatology , University Medical Centre Ljubljana , Slovenia
| | - Ž Rotar
- a Department of Rheumatology , University Medical Centre Ljubljana , Slovenia
| | - N Gašperšič
- a Department of Rheumatology , University Medical Centre Ljubljana , Slovenia
| | - S Sodin-Šemrl
- a Department of Rheumatology , University Medical Centre Ljubljana , Slovenia
| | - J Žibert
- d Faculty of Health Sciences , University of Ljubljana , Slovenia
| | - J Omersel
- e Faculty of Pharmacy , University of Ljubljana , Slovenia
| | - A V Chibalin
- f Department of Molecular Medicine and Surgery, Integrative Physiology , Karolinska Institutet , Stockholm , Sweden
| | - M Tomšič
- a Department of Rheumatology , University Medical Centre Ljubljana , Slovenia
| | - A Ambrožič
- a Department of Rheumatology , University Medical Centre Ljubljana , Slovenia
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Lojk J, Mis K, Pirkmajer S, Pavlin M. siRNA delivery into cultured primary human myoblasts - optimization of electroporation parameters and theoretical analysis. Bioelectromagnetics 2015; 36:551-63. [DOI: 10.1002/bem.21936] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Accepted: 09/02/2015] [Indexed: 02/02/2023]
Affiliation(s)
- Jasna Lojk
- Faculty of Electrical Engineering; University of Ljubljana; Ljubljana Slovenia
| | - Katarina Mis
- Institute of Pathophysiology, Faculty of Medicine; University of Ljubljana; Ljubljana Slovenia
| | - Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine; University of Ljubljana; Ljubljana Slovenia
| | - Mojca Pavlin
- Faculty of Electrical Engineering; University of Ljubljana; Ljubljana Slovenia
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Perdan-Pirkmajer K, Pirkmajer S, Thevis M, Thomas A, Praprotnik S, Hočevar A, Rotar Ž, Gašperšič N, Sodin-Šemrl S, Žibert J, Omersel J, Chibalin A, Tomišič M, Ambrožič A. SAT0219 Methotrexate-Induced Reduction in Concentration of HBA1C in Rheumatoid and Psoriatic Arthritis is Not Correlated with Sustained Increase in Erythrocyte ZMP or Urinary Aicar Concentration. Ann Rheum Dis 2015. [DOI: 10.1136/annrheumdis-2015-eular.2329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Lojk J, Bregar VB, Rajh M, Miš K, Kreft ME, Pirkmajer S, Veranič P, Pavlin M. Cell type-specific response to high intracellular loading of polyacrylic acid-coated magnetic nanoparticles. Int J Nanomedicine 2015; 10:1449-62. [PMID: 25733835 PMCID: PMC4340463 DOI: 10.2147/ijn.s76134] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Magnetic nanoparticles (NPs) are a special type of NP with a ferromagnetic, electron-dense core that enables several applications such as cell tracking, hyperthermia, and magnetic separation, as well as multimodality. So far, superparamagnetic iron oxide NPs (SPIONs) are the only clinically approved type of metal oxide NPs, but cobalt ferrite NPs have properties suitable for biomedical applications as well. In this study, we analyzed the cellular responses to magnetic cobalt ferrite NPs coated with polyacrylic acid (PAA) in three cell types: Chinese Hamster Ovary (CHO), mouse melanoma (B16) cell line, and primary human myoblasts (MYO). We compared the internalization pathway, intracellular trafficking, and intracellular fate of our NPs using fluorescence and transmission electron microscopy (TEM) as well as quantified NP uptake and analyzed uptake dynamics. We determined cell viability after 24 or 96 hours’ exposure to increasing concentrations of NPs, and quantified the generation of reactive oxygen species (ROS) upon 24 and 48 hours’ exposure. Our NPs have been shown to readily enter and accumulate in cells in high quantities using the same two endocytic pathways; mostly by macropinocytosis and partially by clathrin-mediated endocytosis. The cell types differed in their uptake rate, the dynamics of intracellular trafficking, and the uptake capacity, as well as in their response to higher concentrations of internalized NPs. The observed differences in cell responses stress the importance of evaluation of NP–cell interactions on several different cell types for better prediction of possible toxic effects on different cell and tissue types in vivo.
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Affiliation(s)
- Jasna Lojk
- Group for Nano and Biotechnological Applications, Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Vladimir B Bregar
- Group for Nano and Biotechnological Applications, Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Maruša Rajh
- Group for Nano and Biotechnological Applications, Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - Katarina Miš
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Mateja Erdani Kreft
- Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Peter Veranič
- Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Mojca Pavlin
- Group for Nano and Biotechnological Applications, Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia
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Pirkmajer S, Kulkarni SS, Tom RZ, Ross FA, Hawley SA, Hardie DG, Zierath JR, Chibalin AV. Methotrexate promotes glucose uptake and lipid oxidation in skeletal muscle via AMPK activation. Diabetes 2015; 64:360-9. [PMID: 25338814 PMCID: PMC5703413 DOI: 10.2337/db14-0508] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Methotrexate (MTX) is a widely used anticancer and antirheumatic drug that has been postulated to protect against metabolic risk factors associated with type 2 diabetes, although the mechanism remains unknown. MTX inhibits 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase/inosine monophosphate cyclohydrolase (ATIC) and thereby slows the metabolism of 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranosyl-5'-monophosphate (ZMP) and its precursor AICAR, which is a pharmacological AMPK activator. We explored whether MTX promotes AMPK activation in cultured myotubes and isolated skeletal muscle. We found MTX markedly reduced the threshold for AICAR-induced AMPK activation and potentiated glucose uptake and lipid oxidation. Gene silencing of the MTX target ATIC activated AMPK and stimulated lipid oxidation in cultured myotubes. Furthermore, MTX activated AMPK in wild-type HEK-293 cells. These effects were abolished in skeletal muscle lacking the muscle-specific, ZMP-sensitive AMPK-γ3 subunit and in HEK-293 cells expressing a ZMP-insensitive mutant AMPK-γ2 subunit. Collectively, our findings underscore a role for AMPK as a direct molecular link between MTX and energy metabolism in skeletal muscle. Cotherapy with AICAR and MTX could represent a novel strategy to treat metabolic disorders and overcome current limitations of AICAR monotherapy.
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Affiliation(s)
- Sergej Pirkmajer
- Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Sameer S Kulkarni
- Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Robby Z Tom
- Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Fiona A Ross
- Division of Cell Signalling & Immunology, College of Life Sciences, University of Dundee, Dundee, Scotland, U.K
| | - Simon A Hawley
- Division of Cell Signalling & Immunology, College of Life Sciences, University of Dundee, Dundee, Scotland, U.K
| | - D Grahame Hardie
- Division of Cell Signalling & Immunology, College of Life Sciences, University of Dundee, Dundee, Scotland, U.K
| | - Juleen R Zierath
- Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden Department of Physiology and Pharmacology, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Alexander V Chibalin
- Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
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Perdan-Pirkmajer K, Pirkmajer S, Hočevar A, Rotar Ž, Gašperšič N, Praprotnik S, Tomšič M, Ambrožič A. AB0334 Methotrexate Reduces Hba1c in Non-Diabetic Patients with Newly Diagnosed Rheumatoid Arthritis or Psoriatic Arthritis. Ann Rheum Dis 2014. [DOI: 10.1136/annrheumdis-2014-eular.2995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Gros K, Parato G, Pirkmajer S, Mis K, Podbregar M, Grubic Z, Lorenzon P, Mars T. Non-synaptic roles of acetylcholinesterase and agrin. J Mol Neurosci 2013; 53:454-60. [PMID: 24326956 DOI: 10.1007/s12031-013-0188-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Accepted: 11/18/2013] [Indexed: 01/25/2023]
Abstract
Proteins in living organisms have names that are usually derived from their function in the biochemical system their discoverer was investigating. Typical examples are acetylcholinesterase and agrin; however, for both of these, various other functions that are not related to the cholinergic system have been revealed. Our investigations have been focused on the alternative roles of acetylcholinesterase and agrin in the processes of muscle development and regeneration. Previously, we described a role for agrin in the development of excitability in muscle contraction. In this study, we report the effects of agrin on secretion of interleukin 6 in developing human muscle. At the myoblast stage, agrin increases interleukin 6 secretion. This effect seems to be general as it was observed in all of the cell models analysed (human, mouse, cell lines). After fusion of myoblasts into myotubes, the effects of agrin are no longer evident, although agrin has further effects at the innervation stage, at least in in vitro innervated human muscle. These effects of agrin are another demonstration of its non-synaptic roles that are apparently developmental-stage specific. Our data support the view that acetylcholinesterase and agrin participate in various processes during development of skeletal muscle.
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Affiliation(s)
- Katarina Gros
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
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Mis K, Matkovic U, Pirkmajer S, Sciancalepore M, Lorenzon P, Mars T, Grubic Z. Acetylcholinesterase and agrin: different functions, similar expression patterns, multiple roles. Chem Biol Interact 2012; 203:297-301. [PMID: 23117006 DOI: 10.1016/j.cbi.2012.10.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 10/16/2012] [Accepted: 10/17/2012] [Indexed: 12/31/2022]
Abstract
Acetylcholinesterase (AChE) and agrin play unique functional roles in the neuromuscular junction (NMJ). AChE is a cholinergic and agrin a synaptogenetic component. In spite of their different functions, they share several common features: their targeting is determined by alternative splicing; unlike most other NMJ components they are expressed in both, muscle and motor neuron and both reside on the synaptic basal lamina of the NMJ. Also, both were reported to play various nonjunctional roles. However, while the origin of basal lamina bound agrin is undoubtedly neural, the neural origin of AChE, which is anchored to the basal lamina with collagenic tail ColQ, is elusive. Hypothesizing that motor neuron proteins targeted to the NMJ basal lamina share common temporal pattern of expression, which is coordinated with the formation of basal lamina, we compared expression of agrin isoforms with the expression of AChE-T and ColQ in the developing rat spinal cord at the stages before and after the formation of NMJ basal lamina. Cellular origin of AChE-T and agrin was determined by in situ hybridization and their quantitative levels by RT PCR. We found parallel increase in expression of the synaptogenetic (agrin 8) isoform of agrin and ColQ after the formation of basal lamina supporting the view that ColQ bound AChE and agrin 8 isoform are destined to the basal lamina. Catalytic AChE-T subunit and agrin isoforms 19 and 0 followed different expression patterns. In accordance with the reports of other authors, our investigations also revealed various alternative functions for AChE and agrin. We have already demonstrated participation of AChE in myoblast apoptosis; here we present the evidence that agrin promotes the maturation of heavy myosin chains and the excitation-contraction coupling. These results show that common features of AChE and agrin extend to their capacity to play multiple roles in muscle development.
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Affiliation(s)
- Katarina Mis
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
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Kržan M, Novak M, Pirkmajer S, Perdan-Pirkmajer K. Characteristics of low affinity high capacity histamine uptake into neonatal rat astrocytes. BMC Pharmacol Toxicol 2012. [PMCID: PMC3506286 DOI: 10.1186/2050-6511-13-s1-a19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Affiliation(s)
- Mojca Kržan
- Department of Pharmacology and Experimental Toxicology Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Maša Novak
- Department of Pharmacology and Experimental Toxicology Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Katja Perdan-Pirkmajer
- Department of Pharmacology and Experimental Toxicology Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia
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Terbuc V, Novak M, Perdan-Pirkmajer K, Pirkmajer S, Kržan M. Low affinity histamine uptake into neonatal rat astrocytes does not involve OCT. BMC Pharmacol Toxicol 2012. [PMCID: PMC3506290 DOI: 10.1186/2050-6511-13-s1-a32] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Perdan-Pirkmajer K, Pirkmajer S, Černe K, Kržan M. Molecular and kinetic characterization of histamine transport into adult rat cultured astrocytes. Neurochem Int 2012; 61:415-22. [DOI: 10.1016/j.neuint.2012.05.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Revised: 04/29/2012] [Accepted: 05/01/2012] [Indexed: 12/22/2022]
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Benziane B, Björnholm M, Pirkmajer S, Austin RL, Kotova O, Viollet B, Zierath JR, Chibalin AV. Activation of AMP-activated protein kinase stimulates Na+,K+-ATPase activity in skeletal muscle cells. J Biol Chem 2012; 287:23451-63. [PMID: 22610379 DOI: 10.1074/jbc.m111.331926] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Contraction stimulates Na(+),K(+)-ATPase and AMP-activated protein kinase (AMPK) activity in skeletal muscle. Whether AMPK activation affects Na(+),K(+)-ATPase activity in skeletal muscle remains to be determined. Short term stimulation of rat L6 myotubes with the AMPK activator 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR), activates AMPK and promotes translocation of the Na(+),K(+)-ATPase α(1)-subunit to the plasma membrane and increases Na(+),K(+)-ATPase activity as assessed by ouabain-sensitive (86)Rb(+) uptake. Cyanide-induced artificial anoxia, as well as a direct AMPK activator (A-769662) also increase AMPK phosphorylation and Na(+),K(+)-ATPase activity. Thus, different stimuli that target AMPK concomitantly increase Na(+),K(+)-ATPase activity. The effect of AICAR on Na(+),K(+)-ATPase in L6 myotubes was attenuated by Compound C, an AMPK inhibitor, as well as siRNA-mediated AMPK silencing. The effects of AICAR on Na(+),K(+)-ATPase were completely abolished in cultured primary mouse muscle cells lacking AMPK α-subunits. AMPK stimulation leads to Na(+),K(+)-ATPase α(1)-subunit dephosphorylation at Ser(18), which may prevent endocytosis of the sodium pump. AICAR stimulation leads to methylation and dephosphorylation of the catalytic subunit of the protein phosphatase (PP) 2A in L6 myotubes. Moreover, AICAR-triggered dephosphorylation of the Na(+),K(+)-ATPase was prevented in L6 myotubes deficient in PP2A-specific protein phosphatase methylesterase-1 (PME-1), indicating a role for the PP2A·PME-1 complex in AMPK-mediated regulation of Na(+),K(+)-ATPase. Thus contrary to the common paradigm, we report AMPK-dependent activation of an energy-consuming ion pumping process. This activation may be a potential mechanism by which exercise and metabolic stress activate the sodium pump in skeletal muscle.
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Affiliation(s)
- Boubacar Benziane
- Department of Physiology and Pharmacology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
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Boon H, Kostovski E, Pirkmajer S, Song M, Lubarski I, Iversen PO, Hjeltnes N, Widegren U, Chibalin AV. Influence of chronic and acute spinal cord injury on skeletal muscle Na+-K+-ATPase and phospholemman expression in humans. Am J Physiol Endocrinol Metab 2012; 302:E864-71. [PMID: 22275761 DOI: 10.1152/ajpendo.00625.2011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Na(+)-K(+)-ATPase is an integral membrane protein crucial for the maintenance of ion homeostasis and skeletal muscle contractibility. Skeletal muscle Na(+)-K(+)-ATPase content displays remarkable plasticity in response to long-term increase in physiological demand, such as exercise training. However, the adaptations in Na(+)-K(+)-ATPase function in response to a suddenly decreased and/or habitually low level of physical activity, especially after a spinal cord injury (SCI), are incompletely known. We tested the hypothesis that skeletal muscle content of Na(+)-K(+)-ATPase and the associated regulatory proteins from the FXYD family is altered in SCI patients in a manner dependent on the severity of the spinal cord lesion and postinjury level of physical activity. Three different groups were studied: 1) six subjects with chronic complete cervical SCI, 2) seven subjects with acute, complete cervical SCI, and 3) six subjects with acute, incomplete cervical SCI. The individuals in groups 2 and 3 were studied at months 1, 3, and 12 postinjury, whereas individuals with chronic SCI were compared with an able-bodied control group. Chronic complete SCI was associated with a marked decrease in [(3)H]ouabain binding site concentration in skeletal muscle as well as reduced protein content of the α(1)-, α(2)-, and β(1)-subunit of the Na(+)-K(+)-ATPase. In line with this finding, expression of the Na(+)-K(+)-ATPase α(1)- and α(2)-subunits progressively decreased during the first year after complete but not after incomplete SCI. The expression of the regulatory protein phospholemman (PLM or FXYD1) was attenuated after complete, but not incomplete, cervical SCI. In contrast, FXYD5 was substantially upregulated in patients with complete SCI. In conclusion, the severity of the spinal cord lesion and the level of postinjury physical activity in patients with SCI are important factors controlling the expression of Na(+)-K(+)-ATPase and its regulatory proteins PLM and FXYD5.
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Affiliation(s)
- Hanneke Boon
- Department of Molecular Medicine and Surgery, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
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Galuska D, Pirkmajer S, Barrès R, Ekberg K, Wahren J, Chibalin AV. C-peptide increases Na,K-ATPase expression via PKC- and MAP kinase-dependent activation of transcription factor ZEB in human renal tubular cells. PLoS One 2011; 6:e28294. [PMID: 22162761 PMCID: PMC3230608 DOI: 10.1371/journal.pone.0028294] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Accepted: 11/04/2011] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Replacement of proinsulin C-peptide in type 1 diabetes ameliorates nerve and kidney dysfunction, conditions which are associated with a decrease in Na,K-ATPase activity. We determined the molecular mechanism by which long term exposure to C-peptide stimulates Na,K-ATPase expression and activity in primary human renal tubular cells (HRTC) in control and hyperglycemic conditions. METHODOLOGY/PRINCIPAL FINDINGS HRTC were cultured from the outer cortex obtained from patients undergoing elective nephrectomy. Ouabain-sensitive rubidium ((86)Rb(+)) uptake and Na,K-ATPase activity were determined. Abundance of Na,K-ATPase was determined by Western blotting in intact cells or isolated basolateral membranes (BLM). DNA binding activity was determined by electrical mobility shift assay (EMSA). Culturing of HRTCs for 5 days with 1 nM, but not 10 nM of human C-peptide leads to increase in Na,K-ATPase α(1)-subunit protein expression, accompanied with increase in (86)Rb(+) uptake, both in normal- and hyperglycemic conditions. Na,K-ATPase α(1)-subunit expression and Na,K-ATPase activity were reduced in BLM isolated from cells cultured in presence of high glucose. Exposure to1 nM, but not 10 nM of C-peptide increased PKCε phosphorylation as well as phosphorylation and abundance of nuclear ERK1/2 regardless of glucose concentration. Exposure to 1 nM of C-peptide increased DNA binding activity of transcription factor ZEB (AREB6), concomitant with Na,K-ATPase α(1)-subunit mRNA expression. Effects of 1 nM C-peptide on Na,K-ATPase α(1)-subunit expression and/or ZEB DNA binding activity in HRTC were abolished by incubation with PKC or MEK1/2 inhibitors and ZEB siRNA silencing. CONCLUSIONS/SIGNIFICANCE Despite activation of ERK1/2 and PKC by hyperglycemia, a distinct pool of PKCs and ERK1/2 is involved in regulation of Na,K-ATPase expression and activity by C-peptide. Most likely C-peptide stimulates sodium pump expression via activation of ZEB, a transcription factor that has not been previously implicated in C-peptide-mediated signaling. Importantly, only physiological concentrations of C-peptide elicit this effect.
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Affiliation(s)
- Dana Galuska
- Section of Integrative Physiology, Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Sergej Pirkmajer
- Section of Integrative Physiology, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Romain Barrès
- Section of Integrative Physiology, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Karin Ekberg
- Section of Integrative Physiology, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - John Wahren
- Section of Integrative Physiology, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Alexander V. Chibalin
- Section of Integrative Physiology, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
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Benziane B, Widegren U, Pirkmajer S, Henriksson J, Stepto NK, Chibalin AV. Effect of exercise and training on phospholemman phosphorylation in human skeletal muscle. Am J Physiol Endocrinol Metab 2011; 301:E456-66. [PMID: 21653224 DOI: 10.1152/ajpendo.00533.2010] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Phospholemman (PLM, FXYD1) is a partner protein and regulator of the Na(+)-K(+)-ATPase (Na(+)-K(+) pump). We explored the impact of acute and short-term training exercise on PLM physiology in human skeletal muscle. A group of moderately trained males (n = 8) performed a 1-h acute bout of exercise by utilizing a one-legged cycling protocol. Muscle biopsies were taken from vastus lateralis at 0 and 63 min (non-exercised leg) and 30 and 60 min (exercised leg). In a group of sedentary males (n = 9), we determined the effect of a 10-day intense aerobic cycle training on Na(+)-K(+)-ATPase subunit expression, PLM phosphorylation, and total PLM expression as well as PLM phosphorylation in response to acute exercise (1 h at ∼72% Vo(2peak)). Biopsies were taken at rest, immediately following, and 3 h after an acute exercise bout before and at the conclusion of the 10-day training study. PLM phosphorylation was increased both at Ser(63) and Ser(68) immediately after acute exercise (75%, P < 0.05, and 30%, P < 0.05, respectively). Short-term training had no adaptive effect on PLM phosphorylation at Ser(63) and Ser(68), nor was the total amount of PLM altered posttraining. The protein expressions of α(1)-, α(2)-,and β(1)-subunits of Na(+)-K(+)-ATPase were increased after training (113%, P < 0.05, 49%, P < 0.05, and 27%, P < 0.05, respectively). Whereas an acute bout of exercise increased the phosphorylation of PKCα/βII on Thr(638/641) pre- and posttraining, phosphorylation of PKCζ/λ on Thr(403/410) was increased in response to acute exercise only after the 10-day training. In conclusion, we show that only acute exercise, and not short-term training, increases phosphorylation of PLM on Ser(63) and Ser(68), and data from one-legged cycling indicate that this effect of exercise on PLM phosphorylation is not due to systemic factors. Our results provide evidence that phosphorylation of PLM may play a role in the acute regulation of the Na(+)-K(+)-ATPase response to exercise.
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Affiliation(s)
- Boubacar Benziane
- Dept. of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
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Abstract
Many stress conditions are accompanied by skeletal muscle dysfunction and regeneration, which is essentially a recapitulation of the embryonic development. However, regeneration usually occurs under conditions of hypothalamus-pituitary-adrenal gland axis activation and therefore increased glucocorticoid (GC) levels. Glucocorticoid receptor (GR), the main determinant of cellular responsiveness to GCs, exists in two isoforms (GRalpha and GRbeta) in humans. While the role of GRalpha is well characterized, GRbeta remains an elusive player in GC signalling. To elucidate basic characteristics of GC signalling in the regenerating human skeletal muscle we assessed GRalpha and GRbeta expression pattern in cultured human myoblasts and myotubes and their response to 24-hour dexamethasone (DEX) treatment. There was no difference in GRalpha mRNA and protein expression or DEX-mediated GRalpha down-regulation in myoblasts and myotubes. GRbeta mRNA level was very low in myoblasts and remained unaffected by differentiation and/or DEX. GRbeta protein could not be detected. These results indicate that response to GCs is established very early during human skeletal muscle regeneration and that it remains practically unchanged before innervation is established. Very low GRbeta mRNA expression and inability to detect GRbeta protein suggests that GRbeta is not a major player in the early stages of human skeletal muscle regeneration.
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Affiliation(s)
- D Filipović
- Laboratory of Molecular Biology and Endocrinology, Institute of Nuclear Sciences Vinča, Belgrade, Serbia
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Abstract
Serum starvation is one of the most frequently performed procedures in molecular biology and there are literally thousands of research papers reporting its use. In fact, this method has become so ingrained in certain areas of research that reports often simply state that cells were serum starved without providing any factual details as to how the procedure was carried out. Even so, we quite obviously lack unequivocal terminology, standard protocols, and perhaps most surprisingly, a common conceptual basis when performing serum starvation. Such inconsistencies not only hinder interstudy comparability but can lead to opposing and inconsistent experimental results. Although it is frequently assumed that serum starvation reduces basal activity of cells, available experimental data do not entirely support this notion. To address this important issue, we studied primary human myotubes, rat L6 myotubes and human embryonic kidney (HEK)293 cells under different serum starvation conditions and followed time-dependent changes in important signaling pathways such as the extracellular signal-regulated kinase 1/2, the AMP-activated protein kinase, and the mammalian target of rapamycin. Serum starvation induced a swift and dynamic response, which displayed obvious qualitative and quantitative differences across different cell types and experimental conditions despite certain unifying features. There was no uniform reduction in basal signaling activity. Serum starvation clearly represents a major event that triggers a plethora of divergent responses and has therefore great potential to interfere with the experimental results and affect subsequent conclusions.
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Affiliation(s)
- Sergej Pirkmajer
- Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
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Pirkmajer S, Filipovic D, Mars T, Mis K, Grubic Z. HIF-1alpha response to hypoxia is functionally separated from the glucocorticoid stress response in the in vitro regenerating human skeletal muscle. Am J Physiol Regul Integr Comp Physiol 2010; 299:R1693-700. [PMID: 20943857 DOI: 10.1152/ajpregu.00133.2010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Injury of skeletal muscle is followed by muscle regeneration in which new muscle tissue is formed from the proliferating mononuclear myoblasts, and by systemic response to stress that exposes proliferating myoblasts to increased glucocorticoid (GC) concentration. Because of its various causes, hypoxia is a frequent condition affecting skeletal muscle, and therefore both processes, which importantly determine the outcome of the injury, often proceed under hypoxic conditions. It is therefore important to identify and characterize in proliferating human myoblasts: 1) response to hypoxia which is generally organized by hypoxia-inducible factor-1α (HIF-1α); 2) response to GCs which is mediated through the isoforms of glucocorticoid receptors (GRs) and 11β-hydroxysteroid dehydrogenases (11β-HSDs), and 3) the response to GCs under the hypoxic conditions and the influence of this combination on the factors controlling myoblast proliferation. Using real-time PCR, Western blotting, and HIF-1α small-interfering RNA silencing, we demonstrated that cultured human myoblasts possess both, the HIF-1α-based response to hypoxia, and the GC response system composed of GRα and types 1 and 2 11β-HSDs. However, using combined dexamethasone and hypoxia treatments, we demonstrated that these two systems operate practically without mutual interactions. A seemingly surprising separation of the two systems that both organize response to hypoxic stress can be explained on the evolutionary basis: the phylogenetically older HIF-1α response is a protection at the cellular level, whereas the GC stress response protects the organism as a whole. This necessitates actions, like downregulation of IL-6 secretion and vascular endothelial growth factor, that might not be of direct benefit for the affected myoblasts.
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Affiliation(s)
- Sergej Pirkmajer
- Laboratory for Molecular Neurobiology, Institute of Pathophysiology, Faculty of Medicine, Univ. of Ljubljana, Zaloska 4, 1000 Ljubljana, Slovenia
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