1
|
Inglebert Y, Wu PY, Tourbina-Kolomiets J, Dang CL, McKinney RA. Synaptopodin is required for long-term depression at Schaffer collateral-CA1 synapses. Mol Brain 2024; 17:17. [PMID: 38566234 PMCID: PMC10988887 DOI: 10.1186/s13041-024-01089-3] [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: 09/28/2023] [Accepted: 03/24/2024] [Indexed: 04/04/2024] Open
Abstract
Synaptopodin (SP), an actin-associated protein found in telencephalic neurons, affects activity-dependant synaptic plasticity and dynamic changes of dendritic spines. While being required for long-term depression (LTD) mediated by metabotropic glutamate receptor (mGluR-LTD), little is known about its role in other forms of LTD induced by low frequency stimulation (LFS-LTD) or spike-timing dependent plasticity (STDP). Using electrophysiology in ex vivo hippocampal slices from SP-deficient mice (SPKO), we show that absence of SP is associated with a deficit of LTD at Sc-CA1 synapses induced by LFS-LTD and STDP. As LTD is known to require AMPA- receptors internalization and IP3-receptors calcium signaling, we tested by western blotting and immunochemistry if there were changes in their expression which we found to be reduced. While we were not able to induce LTD, long-term potentiation (LTP), albeit diminished in SPKO, can be recovered by using a stronger stimulation protocol. In SPKO we found no differences in NMDAR, which are the primary site of calcium signalling to induce LTP. Our study shows, for the first time, the key role of the requirement of SP to allow induction of activity-dependant LTD at Sc-CA1 synapses.
Collapse
Affiliation(s)
- Yanis Inglebert
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada.
- Current address Department of Neurosciences, Montreal University, Montreal, Canada.
| | - Pei You Wu
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada
| | | | - Cong Loc Dang
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada
| | - R Anne McKinney
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada.
| |
Collapse
|
2
|
Xia J, Huang Y, Ma M, Liu F, Cao B. Downregulating lncRNA MIAT attenuates apoptosis of podocytes exposed to high glucose. Acta Diabetol 2024; 61:451-460. [PMID: 38072843 DOI: 10.1007/s00592-023-02213-w] [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] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 11/08/2023] [Indexed: 03/27/2024]
Abstract
AIMS Diabetic nephropathy (DN), a destructive complication of diabetes mellitus (DM), is one of the leading causes of end-stage renal disease (ESRD). This study aimed to investigate the role of long non-coding RNA (lncRNA) MIAT in high-glucose (HG)-induced podocyte injury associated with DN. METHODS Three human kidney podocyte (HKP) cultures were treated with HG to mimic DN. Expression of lncRNA MIAT, podocyte-specific and injury-related proteins, and apoptosis were assessed before and after MIAT knockdown using MIAT shRNAs. RESULTS MIAT expression was upregulated in HKPs in response to glucose stress. HG treatment resulted in a significant increase in the apoptotic rate, Bax level, and levels of injury-related proteins desmin, fibroblast-specific protein 1 (FSP-1), and smooth muscle α-actin (α-SMA), and a significant reduction in Bcl-2 levels and the levels of podocyte-specific proteins synaptopodin and podocin. Transfection of HKPs with shRNAs significantly reduced MIAT levels (p < 0.05) and attenuated apoptosis in HG-medium. Correspondingly, the levels of synaptopodin and podocin were upregulated, and desmin, FSP-1, and α-SMA were reduced (p < 0.05). Western blot analysis also showed that anti-apoptotic active caspase-3 and Bax and proapoptotic Bcl-2 were elevated and decreased, respectively, after MIAT knockdown, suggesting that apoptosis pathways are deactivated after MIAT downregulation. CONCLUSIONS High glucose upregulates MIAT level in HKPs and induces cellular injury. Knockdown of MIAT alleviates the injury likely via deactivating apoptosis pathways.
Collapse
Affiliation(s)
- Jiayi Xia
- Department of Endocrinology, The First Affiliated Hospital of Guizhou University of Traditional Chinese Medicine, Guiyang, 550001, Guizhou, China
| | - Yan Huang
- Department of Medical Insurance, The First Affiliated Hospital of Guizhou University of Traditional Chinese Medicine, Guiyang, 550001, Guizhou, China
| | - Min Ma
- Department of Gynecology, Graduate School of Guizhou, University of Traditional Chinese Medicine, Guiyang, 550001, Guizhou, China
| | - Fang Liu
- Department of Coloproctology, The First Affiliated Hospital of Guizhou University of Traditional Chinese Medicine, Guiyang, 550001, Guizhou, China.
| | - Bo Cao
- Department of Coloproctology, The First Affiliated Hospital of Guizhou University of Traditional Chinese Medicine, Guiyang, 550001, Guizhou, China.
| |
Collapse
|
3
|
Speranza L, Inglebert Y, De Sanctis C, Wu PY, Kalinowska M, McKinney RA, Francesconi A. Stabilization of Spine Synaptopodin by mGluR1 Is Required for mGluR-LTD. J Neurosci 2022; 42:1666-78. [PMID: 35046120 DOI: 10.1523/JNEUROSCI.1466-21.2022] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Revised: 01/07/2022] [Accepted: 01/10/2022] [Indexed: 02/03/2023] Open
Abstract
Dendritic spines, actin-rich protrusions forming the postsynaptic sites of excitatory synapses, undergo activity-dependent molecular and structural remodeling. Activation of Group 1 metabotropic glutamate receptors (mGluR1 and mGluR5) by synaptic or pharmacological stimulation, induces LTD, but whether this is accompanied with spine elimination remains unresolved. A subset of telencephalic mushroom spines contains the spine apparatus (SA), an enigmatic organelle composed of stacks of smooth endoplasmic reticulum, whose formation depends on the expression of the actin-bundling protein Synaptopodin. Allocation of Synaptopodin to spines appears governed by cell-intrinsic mechanisms as the relative frequency of spines harboring Synaptopodin is conserved in vivo and in vitro Here we show that expression of Synaptopodin/SA in spines is required for induction of mGluR-LTD at Schaffer collateral-CA1 synapses of male mice. Post-mGluR-LTD, mushroom spines lacking Synaptopodin/SA are selectively lost, whereas spines harboring it are preserved. This process, dependent on activation of mGluR1 but not mGluR5, is conserved in mature mouse neurons and rat neurons of both sexes. Mechanistically, we find that mGluR1 supports physical retention of Synaptopodin within excitatory spine synapses during LTD while triggering lysosome-dependent degradation of the protein residing in dendritic shafts. Together, these results reveal a cellular mechanism, dependent on mGluR1, which enables selective preservation of stronger spines containing Synaptopodin/SA while eliminating weaker ones and potentially countering spurious strengthening by de novo recruitment of Synaptopodin. Overall, our results identify spines with Synaptopodin/SA as the locus of mGluR-LTD and underscore the importance of the molecular microanatomy of spines in synaptic plasticity.SIGNIFICANCE STATEMENT Long-term changes in functional synaptic strength are associated with modification of synaptic connectivity through stabilization or elimination of dendritic spines, the postsynaptic locus of excitatory synapses. How heterogeneous spine microanatomy instructs spine remodeling after long-term synaptic depression (LTD) remains unclear. Metabotropic glutamate receptors mGluR1 and mGluR5 induce a form of LTD critical to circuit function in physiological and disease conditions. Our results identify spines containing the protein Synaptopodin, which enables local assembly of a spine apparatus, as the locus of expression of mGluR-LTD and demonstrate a specific role of mGluR1 in promoting selective loss after mGluR-LTD of mature dendritic spines lacking Synaptopodin/spine apparatus. These findings highlight the fundamental contribution of spine microanatomy in selectively enabling functional and structural plasticity.
Collapse
|
4
|
Kulikov AA, Naumova AA, Aleksandrova EP, Glazova MV, Chernigovskaya EV. Audiogenic kindling stimulates aberrant neurogenesis, synaptopodin expression, and mossy fiber sprouting in the hippocampus of rats genetically prone to audiogenic seizures. Epilepsy Behav 2021; 125:108445. [PMID: 34837844 DOI: 10.1016/j.yebeh.2021.108445] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 11/11/2021] [Accepted: 11/12/2021] [Indexed: 12/12/2022]
Abstract
Temporal lobe epilepsy is associated with considerable structural changes in the hippocampus. Pharmacological and electrical models of temporal lobe epilepsy in animals strongly suggest that hippocampal reorganization is based on seizure-stimulated aberrant neurogenesis but the data are often controversial and hard to interpret. The aim of the present study was to estimate neurogenesis and synaptic remodeling in the hippocampus of Krushinsky-Molodkina (KM) rats genetically prone to audiogenic seizures (AGS). In our experiments we exposed KM rats to audiogenic kindling of different durations (4, 14, and 21 AGS) to model different stages of epilepsy development. Naïve KM rats were used as a control. Our results showed that even 4 AGS stimulated proliferation in the subgranular layer of the dentate gyrus (DG) accompanied with increase in number of doublecortin (DCX)-positive immature granular cells. Elevated number of proliferating cells was also observed in the hilus indicating the enhancement of abnormal migration of neural progenitors. In contrast to the DG, all DCX-positive cells in the hilus expressed VGLUT1/2 and their number was increased indicating that seizure activity accelerates glutamatergic differentiation of ectopic hilar cells. 14-day kindling further stimulated proliferation, abnormal migration, and glutamatergic differentiation of new neurons both in the DG granular and subgranular layers and in the hilus. However, after 21 AGS increased proliferation was observed only in the DG, while the numbers of immature neurons expressed VGLUT1/2 were still enhanced in both hippocampal areas. Audiogenic kindling also stimulated sprouting of mossy fibers and enhanced expression of synaptopodin in the hippocampus indicating generation of new synaptic contacts between granular cells, mossy cells, and CA3 pyramid neurons. Thus, our data suggest that epilepsy progression is associated with exacerbation of aberrant neurogenesis and reorganization of hippocampal neural circuits that contribute to the enhancement and spreading of epileptiform activity.
Collapse
Affiliation(s)
- Alexey A Kulikov
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, 44 Thorez pr., 194223 St. Petersburg, Russia
| | - Alexandra A Naumova
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, 44 Thorez pr., 194223 St. Petersburg, Russia
| | - Ekaterina P Aleksandrova
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, 44 Thorez pr., 194223 St. Petersburg, Russia
| | - Margarita V Glazova
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, 44 Thorez pr., 194223 St. Petersburg, Russia.
| | - Elena V Chernigovskaya
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, 44 Thorez pr., 194223 St. Petersburg, Russia
| |
Collapse
|
5
|
Abstract
Podocytes play an important role in the maintenance of kidney function, and they are the primary focus of many kidney diseases. Podocyte injury results in the shedding of podocyte-derived cellular fragments and podocyte-specific molecular targets into the urine, which may serve as biomarkers of kidney diseases. Intact podocytes, either viable or dead, and podocyte-derived microvesicles could be quantified in the urine by various centrifugation, visualization and culture methods. Podocyte-specific protein targets from the nucleus, cytoplasm, slit-diaphragm, glomerular capillary basement membrane, and cytoskeleton, as well as their corresponding messenger RNA (mRNA), in the urine could be quantified by western blotting, ELISA, or quantitative polymerase chain reaction. Although some of these techniques may be expensive or labor-intensive at present, they may become widely available in the future because of the improvement in technology and automation. The application of urinary podocyte markers for the diagnosis and monitoring of various kidney diseases have been explored but the published data in this area are not sufficiently systematic and lack external validation. Further research should focus on standardizing, comparing, and automizing laboratory methods, as well as defining their added value to the routine clinical tests.
Collapse
|
6
|
Aloni E, Verbitsky S, Kushnireva L, Korkotian E, Segal M. Increased excitability of hippocampal neurons in mature synaptopodin-knockout mice. Brain Struct Funct 2021; 226:2459-2466. [PMID: 34291334 DOI: 10.1007/s00429-021-02346-0] [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] [Received: 05/05/2021] [Accepted: 07/14/2021] [Indexed: 11/28/2022]
Abstract
Synaptopodin (SP) is localized within the spine apparatus, an enigmatic structure located in the neck of spines of central excitatory neurons. It serves as a link between the spine head, where the synapse is located, and the endoplasmic reticulum (ER) in the parent dendrite. SP is also located in the axon initial segment, in association with the cisternal organelle, another structure related to the endoplasmic reticulum. Extensive research using SP knockout (SPKO) mice suggest that SP has a pivotal role in structural and functional plasticity. Consequently, young adult SPKO mice were shown to be deficient in cognitive functions, and in ability to undergo long-term potentiation of reactivity to afferent stimulation. However, although SP expresses differently during maturation, its role in synaptic and intrinsic neuronal mechanisms in adult SPKO mice is still unclear. To address this knowledge gap we analyzed hippocampus bulk mRNA in SPKO mice, and we recorded the activity of CA1 neurons in the mouse hippocampus slice, with both extracellular and patch recording methods. Electrophysiologically, SPKO cells in CA1 region of the dorsal hippocampus were more excitable than wild type (wt) ones. In addition, exposure of mice to a complex environment caused a higher proportion of arc-expressing cells in SPKO than in wt mice hippocampus. These experiments indicate that higher excitability and higher expression of arc staining may reflect SP deficiency in the hippocampus of adult SPKO mice.
Collapse
Affiliation(s)
- E Aloni
- Department of Neurobiology, Weizmann Institute, 76100, Rehovot, Israel
| | - S Verbitsky
- Department of Neurobiology, Weizmann Institute, 76100, Rehovot, Israel
| | - L Kushnireva
- Department of Neurobiology, Weizmann Institute, 76100, Rehovot, Israel
| | - E Korkotian
- Department of Neurobiology, Weizmann Institute, 76100, Rehovot, Israel
| | - M Segal
- Department of Neurobiology, Weizmann Institute, 76100, Rehovot, Israel.
| |
Collapse
|
7
|
Kubo A, Hidaka T, Nakayama M, Sasaki Y, Takagi M, Suzuki H, Suzuki Y. Protective effects of DPP-4 inhibitor on podocyte injury in glomerular diseases. BMC Nephrol 2020; 21:402. [PMID: 32948146 PMCID: PMC7501714 DOI: 10.1186/s12882-020-02060-9] [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: 02/27/2020] [Accepted: 09/08/2020] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Dipeptidyl peptidase-4 (DPP-4) is a serine protease that inhibits the degradation of glucagon-like peptide 1. DPP-4 inhibitors are used worldwide to treat type 2 diabetes mellitus and were recently shown to have pleiotropic effects such as anti-oxidant, anti-inflammatory, and anti-fibrotic actions. DPP-4 inhibitors improve albuminuria and renal injury including glomerular damage independent of its hypoglycemic effect. Although DPP-4 is mainly expressed in the kidney, the physiological function of DPP-4 remains unclear. METHODS The localization of renal DPP-4 activity was determined in human renal biopsy specimens with glycyl-1-prolyl-4-methoxy-2-naphthylamide and the effects of a DPP-4 inhibitor were examined in human cultured podocyte. RESULTS DPP-4 activity under normal conditions was observed in some Bowman's capsular epithelial cells and proximal tubules, but not in the glomerulus. DPP-4 activity was observed in crescent formation in anti-neutrophil myeloperoxidase cytoplasmic antigen antibody nephritis, nodular lesions in diabetic nephropathy, and some podocytes in focal segmental glomerulosclerosis. Notably, the DPP-4 inhibitor saxagliptin suppressed DPP-4 activity in podocytes and the proximal tubules. To assess the effect of DPP-4 inhibitor on podocytes, human cultured podocytes were injured by Adriamycin, which increased DPP-4 activity; this activity was dose-dependently suppressed by saxagliptin. Treatment with saxagliptin maintained the structure of synaptopodin and RhoA. Saxagliptin also improved the detachment of podocytes. CONCLUSIONS DPP-4 activity induces degradation of synaptopodin and reduction of RhoA, resulting in destruction of the podocyte cytoskeleton. Saxagliptin may have pleiotropic effects to prevent podocyte injury.
Collapse
Affiliation(s)
- Ayano Kubo
- Department of Nephrology, Juntendo University Faculty of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Teruo Hidaka
- Department of Nephrology, Juntendo University Faculty of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Maiko Nakayama
- Department of Nephrology, Juntendo University Faculty of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Yu Sasaki
- Department of Nephrology, Juntendo University Faculty of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Miyuki Takagi
- Department of Nephrology, Juntendo University Faculty of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Hitoshi Suzuki
- Department of Nephrology, Juntendo University Faculty of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.,Department of Nephrology and Hypertension, Juntendo University Urayasu Hospital, 2-1-1 Tomioka, Urayasu-City, Chiba, 279-0021, Japan
| | - Yusuke Suzuki
- Department of Nephrology, Juntendo University Faculty of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
| |
Collapse
|
8
|
Trimarchi H, Ceol M, Gianesello L, Priante G, Iotti A, Del Prete D. Downregulation of megalin, cubilin, ClC-5 and podocin in Fabry nephropathy: potential implications in the decreased effectiveness of enzyme replacement therapy. J Nephrol 2021; 34:1307-14. [PMID: 32840752 DOI: 10.1007/s40620-020-00835-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 08/11/2020] [Indexed: 01/21/2023]
Abstract
Fabry disease is an X-linked disorder due to mutations in α-galactosidase A, resulting in the accumulation of enzyme substrates and cell malfunction. Kidney involvement is frequent, affecting all native kidney cell types. Podocyte damage results in proteinuria and chronic kidney disease. End-stage kidney disease is the rule in middle-aged males and some females with the classic phenotype. In podocytes and kidney proximal tubular cells, megalin is one of the molecules involved in enzyme replacement therapy (ERT) cellular absorption. After podocyte damage, podocin concentration is decreased and contributes to progressive proteinuria. We report in a male and a female patient the decreased expression of megalin, cubilin, ClC-5 and podocin compared to controls and chronic kidney disease (CKD) biopsies. Moreover, the decrease in ClC-5, a molecule engaged in endosomal-lysosomal acidification, could also affect ERT. These findings may partially explain some of the dysfunctions described in Fabry nephropathy and could highlight possible alterations in the pharmacokinetics of the delivered enzyme.
Collapse
|
9
|
Keisuke S, Kohei M, Takuji E, Tomoki M, Yuichi M, Rina O, Tsukasa T, Mitsuru O. Role of cathepsin L in idiopathic nephrotic syndrome in children. Med Hypotheses 2020; 141:109718. [PMID: 32289645 DOI: 10.1016/j.mehy.2020.109718] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [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: 03/21/2020] [Accepted: 04/06/2020] [Indexed: 01/12/2023]
Abstract
Nephrotic syndrome (NS) is one of the most common glomerular diseases in children. Glomerular podocyte dysfunction can result in proteinuria, the presence of a large amount of protein in the urine. Podocytes are unique epithelial cells that divide into 3 separate structural and functional segments: a cell body, major processes, and foot processes. Since synaptopodin, dynamin, and actin are crucial components of the podocyte cytoskeleton, degradation of these proteins is associated with cytoskeleton instability, resulting in the development of proteinuria. Cathepsin L (CatL), a cysteine proteinase, plays a crucial role in various renal diseases. CatL expression is elevated in rats with puromycin aminonucleoside-induced nephropathy, which is used as a model of minimal change NS. In CatL-deficient mice, which do not develop proteinuria, dynamin is retained through the escape of CatL-mediated decomposition, resulting in no changes in the filtration barrier of podocytes. However, there is limited information on the roles of CatL in NS. Based on these data, CatL might play an important role in the development of proteinuria. Furthermore, identifying the functions of CatL may contribute to a better understanding of the pathogenesis of childhood-onset NS. We hypothesize that high levels of CatL can lead to cytoskeletal instability of podocytes, resulting in proteinuria in childhood-onset NS.
Collapse
Affiliation(s)
- Sugimoto Keisuke
- Department of Pediatrics, Kindai University, Faculty of Medicine, Osaka, Japan.
| | - Miyazaki Kohei
- Department of Pediatrics, Kindai University, Faculty of Medicine, Osaka, Japan
| | - Enya Takuji
- Department of Pediatrics, Kindai University, Faculty of Medicine, Osaka, Japan
| | - Miyazawa Tomoki
- Department of Pediatrics, Kindai University, Faculty of Medicine, Osaka, Japan
| | - Morimoto Yuichi
- Department of Pediatrics, Kindai University, Faculty of Medicine, Osaka, Japan
| | - Oshima Rina
- Department of Pediatrics, Kindai University, Faculty of Medicine, Osaka, Japan
| | - Takemura Tsukasa
- Department of Pediatrics, Kushimoto Municipality Hospital, Wakayama, Japan
| | - Okada Mitsuru
- Department of Pediatrics, Kindai University, Faculty of Medicine, Osaka, Japan
| |
Collapse
|
10
|
Konietzny A, González-Gallego J, Bär J, Perez-Alvarez A, Drakew A, Demmers JAA, Dekkers DHW, Hammer JA, Frotscher M, Oertner TG, Wagner W, Kneussel M, Mikhaylova M. Myosin V regulates synaptopodin clustering and localization in the dendrites of hippocampal neurons. J Cell Sci 2019; 132:jcs.230177. [PMID: 31371487 PMCID: PMC6737913 DOI: 10.1242/jcs.230177] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [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: 01/21/2019] [Accepted: 07/19/2019] [Indexed: 01/15/2023] Open
Abstract
The spine apparatus (SA) is an endoplasmic reticulum-related organelle that is present in a subset of dendritic spines in cortical and pyramidal neurons, and plays an important role in Ca2+ homeostasis and dendritic spine plasticity. The protein synaptopodin is essential for the formation of the SA and is widely used as a maker for this organelle. However, it is still unclear which factors contribute to its localization at selected synapses, and how it triggers local SA formation. In this study, we characterized development, localization and mobility of synaptopodin clusters in hippocampal primary neurons, as well as the molecular dynamics within these clusters. Interestingly, synaptopodin at the shaft-associated clusters is less dynamic than at spinous clusters. We identify the actin-based motor proteins myosin V (herein referring to both the myosin Va and Vb forms) and VI as novel interaction partners of synaptopodin, and demonstrate that myosin V is important for the formation and/or maintenance of the SA. We found no evidence of active microtubule-based transport of synaptopodin. Instead, new clusters emerge inside spines, which we interpret as the SA being assembled on-site.
Collapse
Affiliation(s)
- Anja Konietzny
- DFG Emmy Noether Group 'Neuronal Protein Transport', Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Judit González-Gallego
- DFG Emmy Noether Group 'Neuronal Protein Transport', Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Julia Bär
- DFG Emmy Noether Group 'Neuronal Protein Transport', Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Alberto Perez-Alvarez
- Institute for Synaptic Physiology, Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Alexander Drakew
- Institute of Structural Neurobiology, Center for Molecular Neurobiology Hamburg, ZMNH, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany.,Institute of Clinical Neuroanatomy, Faculty of Medicine, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany
| | | | - Dick H W Dekkers
- Center for Proteomics, Erasmus MC, 3000 CA Rotterdam, The Netherlands
| | - John A Hammer
- Cell Biology and Physiology Center, National Heart, Lung Blood Institute, National Institutes of Health, Bethesda, MD 20814, USA
| | - Michael Frotscher
- Institute of Structural Neurobiology, Center for Molecular Neurobiology Hamburg, ZMNH, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Thomas G Oertner
- Institute for Synaptic Physiology, Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Wolfgang Wagner
- Department of Molecular Neurogenetics, Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Matthias Kneussel
- Department of Molecular Neurogenetics, Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Marina Mikhaylova
- DFG Emmy Noether Group 'Neuronal Protein Transport', Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| |
Collapse
|
11
|
Zhuravin IA, Dubrovskaya NM, Vasilev DS, Postnikova TY, Zaitsev AV. Prenatal hypoxia produces memory deficits associated with impairment of long-term synaptic plasticity in young rats. Neurobiol Learn Mem 2019; 164:107066. [PMID: 31400467 DOI: 10.1016/j.nlm.2019.107066] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [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: 03/26/2019] [Revised: 07/31/2019] [Accepted: 08/06/2019] [Indexed: 12/18/2022]
Abstract
Prenatal hypoxia often results in dramatic alterations in developmental profiles and behavioral characteristics, including learning and memory, in later life. Despite the accumulation of considerable amounts of experimental data, the mechanisms underlying developmental deficits caused by prenatal hypoxia remain unclear. In the present study, we investigated whether prenatal hypoxia on embryonic day 14 (E14) affected synaptic properties in the hippocampus and hippocampal-related cognitive functions in young rats. We found that 20- to 30-d-old rats subjected to prenatal hypoxia had significantly disturbed basal synaptic transmission in CA3-CA1 synapses and a two-fold decrease in hippocampal long-term synaptic potentiation. These alterations were accompanied by a significant decline in the protein level of GluN2B but not GluN2A NMDA receptor subunits. In addition, the number of synaptopodin-positive dendritic spines in the CA1 area of the hippocampus was reduced in the rats exposed to prenatal hypoxia. These changes resulted in significant learning and memory deficits in a novel object recognition test.
Collapse
Affiliation(s)
- Igor A Zhuravin
- Sechenov Institute of Evolutionary Physiology and Biochemistry of RAS (IEPhB), 44, Toreza pr., Saint Petersburg 194223, Russia
| | - Nadezhda M Dubrovskaya
- Sechenov Institute of Evolutionary Physiology and Biochemistry of RAS (IEPhB), 44, Toreza pr., Saint Petersburg 194223, Russia
| | - Dmitry S Vasilev
- Sechenov Institute of Evolutionary Physiology and Biochemistry of RAS (IEPhB), 44, Toreza pr., Saint Petersburg 194223, Russia
| | - Tatyana Yu Postnikova
- Sechenov Institute of Evolutionary Physiology and Biochemistry of RAS (IEPhB), 44, Toreza pr., Saint Petersburg 194223, Russia
| | - Aleksey V Zaitsev
- Sechenov Institute of Evolutionary Physiology and Biochemistry of RAS (IEPhB), 44, Toreza pr., Saint Petersburg 194223, Russia; Institute of Experimental Medicine, Almazov National Medical Research Centre, 2 Akkuratova Street, Saint Petersburg 197341, Russia.
| |
Collapse
|
12
|
Chen Y, Lin L, Tao X, Song Y, Cui J, Wan J. The role of podocyte damage in the etiology of ischemia-reperfusion acute kidney injury and post-injury fibrosis. BMC Nephrol 2019; 20:106. [PMID: 30922260 PMCID: PMC6438002 DOI: 10.1186/s12882-019-1298-x] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [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] [Received: 05/31/2018] [Accepted: 03/17/2019] [Indexed: 01/07/2023] Open
Abstract
Background To establish a model of chronic renal fibrosis following acute kidney injury (AKI) in BALB/c mice and to observe the effect of AKI on podocyte injury and chronic fibrosis of the kidney. Additional aims included using the model to explore the role of podocyte injury in AKI and post-injury fibrosis. Methods Fifty BALB/C mice were randomly divided into control group (Ctr), sham group (sham), AKI 20 group (renal ischemia, 20 min reperfusion), AKI 30 group (renal ischemia, 30 min reperfusion) and AKI 40 group (renal ischemia, 40 min reperfusion). Mice serum and 24-h urine were collected on the 8th, 9th, 10th, 14th, and 28th days for urinary protein, serum creatinine (Scr) and blood urea nitrogen (BUN) analysis. HE staining, transmission electron microscopy (TEM), Masson staining, Q-PCR, Western Blot and immunohistochemistry were applied. Results Serum Scr and BUN levels across all AKI groups at the 9th day were significantly higher (P < 0.05) than controls, with higher reperfusion groups maintaining that increase up to 28 days (P < 0.05). Compared with Ctr group, the urinary protein of the AKI 40 group significantly rose on the 9th day (P < 0.05), normalizing immediately on the 10th day (P < 0.05). In contrast, the AKI 30 group rose significantly on the 14th day (P < 0.05) maintaining elevated levels for two weeks (P < 0.05). HE staining demonstrated ischemia-dependent renal tissue damage was aggravated in the mild to aggravated AKI groups. Mesangial proliferation, glomerulosclerosis, and tubulointerstitial pathology were also significantly increased in these groups (P < 0.05). Masson staining further showed that glomerular, renal tubular, and interstitial collagen were increased by ischemia in a time-dependent manner. Transmission EM additionally that podocytes of the mild to severe AKI groups displayed extensive fusion, exfoliation and GBM exposure. Synaptopodin, Nephrin, and CD2AP mRNA and protein expression demonstrated ischemic time-dependent decreases, while the TRPC6 was increased. There was a significant difference in the levels of Synaptopodin, Nephrin, CD2AP, and TRPC6 between the mild and severe AKI groups (P < 0.05). Conclusions 1) During the AKI process mice podocyte injury, proteinuria and the subsequent progression into chronic renal fibrosis is observed.2) Podocyte injury may be one of the causes of ischemia-reperfusion acute kidney injury and post-injury fibrosis. Electronic supplementary material The online version of this article (10.1186/s12882-019-1298-x) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Yi Chen
- Department of Nephrology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, 350005, China
| | - Liyu Lin
- Department of Nephrology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, 350005, China
| | - Xuan Tao
- Department of Pathology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
| | - Yankun Song
- Department of Pathology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
| | - Jiong Cui
- Department of Nephrology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, 350005, China
| | - Jianxin Wan
- Department of Nephrology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, 350005, China.
| |
Collapse
|
13
|
Maggio N, Vlachos A. Tumor necrosis factor (TNF) modulates synaptic plasticity in a concentration-dependent manner through intracellular calcium stores. J Mol Med (Berl) 2018; 96:1039-1047. [PMID: 30073573 DOI: 10.1007/s00109-018-1674-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 07/22/2018] [Accepted: 07/23/2018] [Indexed: 12/11/2022]
Abstract
The role of inflammatory signaling pathways in synaptic plasticity has long been identified. Yet, it remains unclear how inflammatory cytokines assert their pleiotropic effects on neural plasticity. Moreover, the neuronal targets through which inflammatory cytokines assert their effects on plasticity remain not well-understood. In an attempt to learn more about the plasticity-modulating effects of the pro-inflammatory cytokine tumor necrosis factor (TNF), we used two-pathway long-term potentiation (LTP) experiments at Schaffer collateral-CA1 synapses to test for concentration-dependent effects of TNF on synaptic plasticity. We report that high concentrations of TNF (1 μg/mL) impair the ability of mouse CA1 pyramidal neurons to express synaptic plasticity without affecting baseline synaptic transmission and/or previously established LTP. Interestingly, 100 ng/mL of TNF has no apparent effect on LTP, while low concentrations (1 ng/mL) promote the ability of neurons to express LTP. These dose-dependent metaplastic effects of TNF are modulated by intracellular calcium stores: Pharmacological activation of intracellular calcium stores with ryanodine (10 μM) reverses the negative effects of TNF[high], and the plasticity-promoting effects of TNF[low] are blocked when intracellular calcium stores are depleted with thapsigargin (1 μM). Consistent with this result, TNF does not promote plasticity in synaptopodin-deficient preparations, which show deficits in neuronal calcium store-mediated synaptic plasticity. Thus, we propose that TNF mediates its pleiotropic effects on synaptic plasticity in a concentration-dependent manner through signaling pathways that are modulated by intracellular calcium stores and require the presence of synaptopodin. These results demonstrate that TNF can act as mediator of metaplasticity, which is of considerable relevance in the context of brain diseases associated with increased TNF levels and alterations in synaptic plasticity. KEY MESSAGES • TNF modulates the ability of neurons to express synaptic plasticity. • High concentrations of TNF impair synaptic plasticity. • Low concentrations of TNF improve synaptic plasticity. • TNF does not affect previously established long-term potentiation. • Plasticity effects of TNF are modulated by intracellular calcium stores.
Collapse
Affiliation(s)
- Nicola Maggio
- Department of Neurology and Sagol Center for Neurosciences, Sheba Medical Center, 52621, Ramat Gan, Israel. .,Department of Neurology, The Chaim Sheba Medical Center, 52621, Tel HaShomer, Israel. .,Talpiot Medical Leadership Program, The Chaim Sheba Medical Center, 52621, Tel HaShomer, Israel. .,Department of Neurology and Neurosurgery, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, 52621, Tel Aviv, Israel.
| | - Andreas Vlachos
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, 79104, Freiburg, Germany.
| |
Collapse
|
14
|
Kannan N, Tang VW. Myosin-1c promotes E-cadherin tension and force-dependent recruitment of α-actinin to the epithelial cell junction. J Cell Sci 2018; 131:jcs.211334. [PMID: 29748378 DOI: 10.1242/jcs.211334] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [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: 09/21/2017] [Accepted: 05/02/2018] [Indexed: 12/26/2022] Open
Abstract
Actomyosin II contractility in epithelial cell plays an essential role in tension-dependent adhesion strengthening. One key unsettling question is how cellular contraction transmits force to the nascent cell-cell adhesion when there is no stable attachment between the nascent adhesion complex and actin filament. Here, we show that myosin-1c is localized to the lateral membrane of polarized epithelial cells and facilitates the coupling between actin and cell-cell adhesion. Knockdown of myosin-1c compromised the integrity of the lateral membrane, reduced the generation of tension at E-cadherin, decreased the strength of cell-cell cohesion in an epithelial cell monolayer and prevented force-dependent recruitment of junctional α-actinin. Application of exogenous force to cell-cell adhesions in a myosin-1c-knockdown cell monolayer fully rescued the localization defect of α-actinin, indicating that junction mechanoregulation remains intact in myosin-1c-depleted cells. Our study identifies a role of myosin-1c in force transmission at the lateral cell-cell interface and underscores a non-junctional contribution to tension-dependent junction regulation.
Collapse
Affiliation(s)
- Nivetha Kannan
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, IL 61801 USA
| | - Vivian W Tang
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, IL 61801 USA
| |
Collapse
|
15
|
Voskarides K, Papagregoriou G, Hadjipanagi D, Petrou I, Savva I, Elia A, Athanasiou Y, Pastelli A, Kkolou M, Hadjigavriel M, Stavrou C, Pierides A, Deltas C. COL4A5 and LAMA5 variants co-inherited in familial hematuria: digenic inheritance or genetic modifier effect? BMC Nephrol 2018; 19:114. [PMID: 29764427 PMCID: PMC5954460 DOI: 10.1186/s12882-018-0906-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [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: 05/04/2017] [Revised: 10/25/2017] [Accepted: 01/21/2018] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND About 40-50% of patients with familial microscopic hematuria (FMH) caused by thin basement membrane nephropathy (TBMN) inherit heterozygous mutations in collagen IV genes (COL4A3, COL4A4). On long follow-up, the full phenotypic spectrum of these patients varies a lot, ranging from isolated MH or MH plus low-grade proteinuria to chronic renal failure of variable degree, including end-stage renal disease (ESRD). METHODS Here, we performed Whole Exome Sequencing (WES) in patients of six families, presenting with autosomal dominant FMH, with or without progression to proteinuria and loss of renal function, all previously found negative for severe collagen IV mutations. Hierarchical filtering of the WES data was performed, followed by mutation prediction analysis, Sanger sequencing and genetic segregation analysis. RESULTS In one family with four patients, we found evidence for the contribution of two co-inherited variants in two crucial genes expressed in the glomerular basement membrane (GBM); LAMA5-p.Pro1243Leu and COL4A5-p.Asp654Tyr. Mutations in COL4A5 cause classical X-linked Alport Syndrome, while rare mutations in the LAMA5 have been reported in patients with focal segmental glomerulosclerosis. The phenotypic spectrum of the patients includes hematuria, proteinuria, focal segmental glomerulosclerosis, loss of kidney function and renal cortical cysts. CONCLUSIONS A modifier role of LAMA5 on the background of a hypomorphic Alport syndrome causing mutation is a possible explanation of our findings. Digenic inheritance is another scenario, following the concept that mutations at both loci more accurately explain the spectrum of symptoms, but further investigation is needed under this concept. This is the third report linking a LAMA5 variant with human renal disease and expanding the spectrum of genes involved in glomerular pathologies accompanied by familial hematurias. The cystic phenotype overlaps with that of a mouse model, which carried a Lama5 hypomorphic mutation that caused severely reduced Lama5 protein levels and produced kidney cysts.
Collapse
Affiliation(s)
- Konstantinos Voskarides
- Molecular Medicine Research Center, Department of Biological Sciences, University of Cyprus, 1, University Avenue, 2109, Nicosia, Cyprus. .,Medical School, University of Cyprus, Nicosia, Cyprus.
| | - Gregory Papagregoriou
- Molecular Medicine Research Center, Department of Biological Sciences, University of Cyprus, 1, University Avenue, 2109, Nicosia, Cyprus
| | - Despina Hadjipanagi
- Molecular Medicine Research Center, Department of Biological Sciences, University of Cyprus, 1, University Avenue, 2109, Nicosia, Cyprus
| | - Ioanelli Petrou
- Molecular Medicine Research Center, Department of Biological Sciences, University of Cyprus, 1, University Avenue, 2109, Nicosia, Cyprus
| | - Isavella Savva
- Molecular Medicine Research Center, Department of Biological Sciences, University of Cyprus, 1, University Avenue, 2109, Nicosia, Cyprus
| | - Avraam Elia
- Department of Pediatric Nephrology, Archbishop Makarios III Hospital, Nicosia, Cyprus
| | | | | | - Maria Kkolou
- Department of Nephrology, Larnaca General Hospital, Larnaca, Cyprus
| | | | | | - Alkis Pierides
- Molecular Medicine Research Center, Department of Biological Sciences, University of Cyprus, 1, University Avenue, 2109, Nicosia, Cyprus.,Hippocrateon Hospital, Nicosia, Cyprus
| | - Constantinos Deltas
- Molecular Medicine Research Center, Department of Biological Sciences, University of Cyprus, 1, University Avenue, 2109, Nicosia, Cyprus. .,College of Medicine, Qatar University, Doha, Qatar.
| |
Collapse
|
16
|
Datta A, Chai YL, Tan JM, Lee JH, Francis PT, Chen CP, Sze SK, Lai MKP. An iTRAQ-based proteomic analysis reveals dysregulation of neocortical synaptopodin in Lewy body dementias. Mol Brain 2017; 10:36. [PMID: 28800743 PMCID: PMC5553757 DOI: 10.1186/s13041-017-0316-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [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: 06/06/2017] [Accepted: 07/21/2017] [Indexed: 02/08/2023] Open
Abstract
Lewy body dementias are the second most common cause of neurodegenerative dementia in the elderly after Alzheimer's disease (AD). The two clinical subgroups of Lewy body dementias, namely, dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD), are differentiated by the chronology of cognitive symptoms relative to parkinsonism. At present, there remains a debate on whether DLB and PDD are separate disease entities, or fall within the same spectrum of Lewy body dementias. In this study, we compared the detergent-soluble proteome via an 8-plex isobaric tag for relative and absolute quantitation (iTRAQ) analysis of pooled lysates from the prefrontal cortex (BA9) of DLB (n = 19) and PDD (n = 21) patients matched a priori for amyloid (total Aβ42) burden, semi-quantitative scores for Lewy bodies and neurofibrillary tangles together with age-matched control (n = 21) subjects. A total of 1914 proteins were confidently identified by iTRAQ (false discovery rate = 0%). None of the proteins showed a significant yet opposite regulation in between DLB and PDD when compared to aged controls in the proteomic data set as well as following immunoblot analysis of the pooled and individual lysates involving all 61 subjects. The postsynaptic protein, synaptopodin (SYNPO) was significantly down-regulated in both DLB and PDD subgroups, suggesting a defective synaptic transmission in the demented patients. In conclusion, the largely similar proteome of DLB and PDD matched for amyloid burden suggests that variations in concomitant AD-related pathology, abnormal post-translational modifications or protein-protein interactions, defective intracellular trafficking or misfolding of proteins could play a part in driving the clinically observed differences between these two subgroups of Lewy body dementias. This further indicates that amyloid-targeting therapeutic strategies may show different efficacies in DLB versus PDD.
Collapse
Affiliation(s)
- Arnab Datta
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Unit 09-01, Centre for Translational Medicine (MD6), 14 Medical Drive, Kent Ridge, Singapore 117599, Singapore. .,Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, Building 10 Room 6N318, Bethesda, MD 20814, USA.
| | - Yuek Ling Chai
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Unit 09-01, Centre for Translational Medicine (MD6), 14 Medical Drive, Kent Ridge, Singapore 117599, Singapore
| | - Jing Min Tan
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Unit 09-01, Centre for Translational Medicine (MD6), 14 Medical Drive, Kent Ridge, Singapore 117599, Singapore
| | - Jasinda H Lee
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Unit 09-01, Centre for Translational Medicine (MD6), 14 Medical Drive, Kent Ridge, Singapore 117599, Singapore
| | - Paul T Francis
- Wolfson Centre for Age-related Diseases, King's College London, Guy's Campus, St Thomas Street, London SE1 1UL, UK
| | - Christopher P Chen
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Unit 09-01, Centre for Translational Medicine (MD6), 14 Medical Drive, Kent Ridge, Singapore 117599, Singapore
| | - Siu Kwan Sze
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Mitchell K P Lai
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Unit 09-01, Centre for Translational Medicine (MD6), 14 Medical Drive, Kent Ridge, Singapore 117599, Singapore. .,Wolfson Centre for Age-related Diseases, King's College London, Guy's Campus, St Thomas Street, London SE1 1UL, UK.
| |
Collapse
|
17
|
Abstract
The central function of renal glomeruli is plasma ultrafiltration for primary urine production. The glomerular filtration barrier consists of a fenestrated endothelium, the glomerular basement membrane and podocytes, mesenchymal-like cells with actin filament-rich protrusions, the "foot processes." Their architecture and function are maintained and regulated by actin and several actin-binding proteins, mutations of which can be causative of glomerular diseases. Since initial immunostaining experiments had demonstrated intense drebrin reactions in renal glomeruli, the distribution of this protein was studied in detail in the kidneys of diverse mammalian species. Double-label confocal laser scanning microscopy revealed drebrin enrichment in mesangial cells of human, bovine, murine, and rat kidneys. In Thy-1.1 nephritic rat glomeruli, the protein was concentrated in mesangial cell processes and upregulated during their formation and remodeling. In adult human and bovine kidneys, drebrin was additionally accumulated in the foot processes of podocytes, a finding confirmed by immunoelectron microscopy. By contrast, podocytes of rodent glomeruli contained significant amounts of drebrin only during early developmental stages. In cultured murine podocytes induced to form cell processes, however, drebrin was concentrated in these protrusions, partly in colocalization with other actin-binding proteins. Protein extracts from human and bovine kidneys comprised 20 S-complexes of drebrin and actin, so-called drebrosomes. In summary, drebrin has to be added to the list of actin-binding proteins regulating actin dynamics of mesangial cell processes and foot processes of podocytes. It will be important to determine its role in hereditary and acquired glomerulopathies.
Collapse
Affiliation(s)
- Wiebke K Ludwig-Peitsch
- Department of Dermatology, Vivantes Klinikum im Friedrichshain, Landsberger Allee 49, 10249, Berlin, Germany.
| |
Collapse
|
18
|
Kwon SK, Kim SJ, Kim HY. Urine synaptopodin excretion is an important marker of glomerular disease progression. Korean J Intern Med 2016; 31:938-43. [PMID: 27604800 PMCID: PMC5016285 DOI: 10.3904/kjim.2015.226] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2015] [Revised: 04/09/2016] [Accepted: 06/21/2016] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND/AIMS Podocytes play an important role in maintaining the glomerular filtration barrier and in formation of the slit diaphragm. Podocyte loss is associated with chronic kidney disease progression, but it is not clear whether urinary podocyte proteins in urine reflect the clinical extent of glomerular damage. We investigated the correlation between the amounts of urinary podocyte proteins and renal function and albuminuria. METHODS The study enrolled 33 patients with diabetic kidney disease or glomerular disease and measured urinary podocytes proteins using Western blotting. Urinary podocyte proteins were measured according to the density of the bands on Western blotting. We measured serum creatinine and the spot urine albumin/creatinine ratio as markers of renal damage, and compared the correlation of urinary podocyte protein in the glomerular disease patients. RESULTS The mean patient age was 49.3 ± 16.5 years, the mean serum creatinine level was 2.30 ± 1.76 mg/dL, and the mean albumin/creatinine ratio was 4.85 ± 3.52. Among the podocyte proteins, urine synaptopodin showed strong correlation with serum creatinine by multivariate regression analysis (p < 0.001) and showed linear correlation (r = 0.429, p < 0.01). Urine podocyte proteins were increased in patients with diabetes, and synaptopodin showed the greatest significant difference (7.68 ± 5.61 vs. 2.56 ± 3.11, p < 0.001), but this might be associated with renal impairment. The urine albumin excretion did not differ between the diabetics and non-diabetics (p = 0.73). CONCLUSIONS Urine synaptopodin is associated with serum creatinine elevation in the patients with glomerulonephritis including diabetic kidney disease regardless of urine albumin excretion. We suggest that the urine synaptopodin level can predict glomerular damage independently of the urine albumin excretion.
Collapse
Affiliation(s)
- Soon Kil Kwon
- Correspondence to Soon Kil Kwon, M.D. Renal Division, Department of Internal Medicine, Chungbuk National University College of Medicine, 1 Chungdae-ro, Seowon-gu, Cheongju 28644, Korea Tel: +82-43-269-6020 Fax: +82-43-273-3252 E-mail:
| | | | | |
Collapse
|
19
|
Verbich D, Becker D, Vlachos A, Mundel P, Deller T, McKinney RA. Rewiring neuronal microcircuits of the brain via spine head protrusions--a role for synaptopodin and intracellular calcium stores. Acta Neuropathol Commun 2016; 4:38. [PMID: 27102112 PMCID: PMC4840984 DOI: 10.1186/s40478-016-0311-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 04/09/2016] [Indexed: 11/26/2022] Open
Abstract
Neurological diseases associated with neuronal death are also accompanied by axonal denervation of connected brain regions. In these areas, denervation leads to a decrease in afferent drive, which may in turn trigger active central nervous system (CNS) circuitry rearrangement. This rewiring process is important therapeutically, since it can partially recover functions and can be further enhanced using modern rehabilitation strategies. Nevertheless, the cellular mechanisms of brain rewiring are not fully understood. We recently reported a mechanism by which neurons remodel their local connectivity under conditions of network-perturbance: hippocampal pyramidal cells can extend spine head protrusions (SHPs), which reach out toward neighboring terminals and form new synapses. Since this form of activity-dependent rewiring is observed only on some spines, we investigated the required conditions. We speculated, that the actin-associated protein synaptopodin, which is involved in several synaptic plasticity mechanisms, could play a role in the formation and/or stabilization of SHPs. Using hippocampal slice cultures, we found that ~70 % of spines with protrusions in CA1 pyramidal neurons contained synaptopodin. Analysis of synaptopodin-deficient neurons revealed that synaptopodin is required for the stability but not the formation of SHPs. The effects of synaptopodin could be linked to its role in Ca2+ homeostasis, since spines with protrusions often contained ryanodine receptors and synaptopodin. Furthermore, disrupting Ca2+ signaling shortened protrusion lifetime. By transgenically reintroducing synaptopodin on a synaptopodin-deficient background, SHP stability could be rescued. Overall, we show that synaptopodin increases the stability of SHPs, and could potentially modulate the rewiring of microcircuitries by making synaptic reorganization more efficient.
Collapse
|
20
|
Collier TJ, O'Malley J, Rademacher DJ, Stancati JA, Sisson KA, Sortwell CE, Paumier KL, Gebremedhin KG, Steece-Collier K. Interrogating the aged striatum: robust survival of grafted dopamine neurons in aging rats produces inferior behavioral recovery and evidence of impaired integration. Neurobiol Dis 2015; 77:191-203. [PMID: 25771169 PMCID: PMC4402284 DOI: 10.1016/j.nbd.2015.03.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [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: 01/17/2015] [Revised: 02/28/2015] [Accepted: 03/03/2015] [Indexed: 01/13/2023] Open
Abstract
Advanced age is the primary risk factor for Parkinson's disease (PD). In PD patients and rodent models of PD, advanced age is associated with inferior symptomatic benefit following intrastriatal grafting of embryonic dopamine (DA) neurons, a pattern believed to result from decreased survival and reinnervation provided by grafted neurons in the aged host. To help understand the capacity of the aged, parkinsonian striatum to be remodeled with new DA terminals, we used a grafting model and examined whether increasing the number of grafted DA neurons in aged rats would translate to enhanced behavioral recovery. Young (3months), middle-aged (15months), and aged (22months) parkinsonian rats were grafted with proportionately increasing numbers of embryonic ventral mesencephalic (VM) cells to evaluate whether the limitations of the graft environment in subjects of advancing age can be offset by increased numbers of transplanted neurons. Despite robust survival of grafted neurons in aged rats, reinnervation of striatal neurons remained inferior and amelioration of levodopa-induced dyskinesias (LID) was delayed or absent. This study demonstrates that: 1) counter to previous evidence, under certain conditions the aged striatum can support robust survival of grafted DA neurons; and 2) unknown factors associated with the aged striatum result in inferior integration of graft and host, and continue to present obstacles to full therapeutic efficacy of DA cell-based therapy in this model of aging.
Collapse
Affiliation(s)
- Timothy J Collier
- Michigan State University, College of Human Medicine, Department of Translational Science and Molecular Medicine & The Udall Center of Excellence in Parkinson's Disease Research, 333 Bostwick Ave NE, Grand Rapids, MI 49503, USA
| | - Jennifer O'Malley
- Cincinnati Children's Hospital Medical Center, Division of Child Neurology, 3333 Burnet Avenue, Cincinnati, OH 45229, USA
| | - David J Rademacher
- Lake Forest College, Department of Psychology, 555 N Sheridan Rd, Lake Forest, IL 60045, USA
| | - Jennifer A Stancati
- Michigan State University, College of Human Medicine, Department of Translational Science and Molecular Medicine & The Udall Center of Excellence in Parkinson's Disease Research, 333 Bostwick Ave NE, Grand Rapids, MI 49503, USA
| | - Kellie A Sisson
- Michigan State University, College of Human Medicine, Department of Translational Science and Molecular Medicine & The Udall Center of Excellence in Parkinson's Disease Research, 333 Bostwick Ave NE, Grand Rapids, MI 49503, USA
| | - Caryl E Sortwell
- Michigan State University, College of Human Medicine, Department of Translational Science and Molecular Medicine & The Udall Center of Excellence in Parkinson's Disease Research, 333 Bostwick Ave NE, Grand Rapids, MI 49503, USA
| | - Katrina L Paumier
- Michigan State University, College of Human Medicine, Department of Translational Science and Molecular Medicine & The Udall Center of Excellence in Parkinson's Disease Research, 333 Bostwick Ave NE, Grand Rapids, MI 49503, USA
| | - Kibrom G Gebremedhin
- Michigan State University, College of Human Medicine, Department of Translational Science and Molecular Medicine & The Udall Center of Excellence in Parkinson's Disease Research, 333 Bostwick Ave NE, Grand Rapids, MI 49503, USA
| | - Kathy Steece-Collier
- Michigan State University, College of Human Medicine, Department of Translational Science and Molecular Medicine & The Udall Center of Excellence in Parkinson's Disease Research, 333 Bostwick Ave NE, Grand Rapids, MI 49503, USA.
| |
Collapse
|
21
|
Grigoryan G, Segal M. Ryanodine-mediated conversion of STP to LTP is lacking in synaptopodin-deficient mice. Brain Struct Funct 2015; 221:2393-7. [PMID: 25772508 DOI: 10.1007/s00429-015-1026-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [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: 08/17/2014] [Accepted: 03/05/2015] [Indexed: 11/24/2022]
Abstract
In previous studies we and others have found that activation of ryanodine receptors (RyRs) facilitate expression of long-term potentiation (LTP) of reactivity to afferent stimulation in hippocampal slices, with a more pronounced action in the ventral hippocampus. We have also been able to link the involvement of synaptopodin (SP), an actin-binding protein, with neuronal plasticity via its interaction with RyRs. To test this link more directly, we have now compared the ability of ryanodine to convert short-term to LTP in hippocampal slices taken from normal and SP-knockout (SPKO) mice. Indeed, SPKO hippocampus expresses lower concentrations of RyRs and in slices of these mice ryanodine is unable to facilitate conversion of short-term to LTP. These observations link functionally SP with calcium stores.
Collapse
Affiliation(s)
- Gayane Grigoryan
- Department of Neurobiology, The Weizmann Institute, 76100, Rehovot, Israel
| | - Menahem Segal
- Department of Neurobiology, The Weizmann Institute, 76100, Rehovot, Israel.
| |
Collapse
|
22
|
Fester L, Labitzke J, Hinz R, Behem C, Horling K, Bernhard T, Bader MI, Vollmer G, Rune GM. Estradiol responsiveness of synaptopodin in hippocampal neurons is mediated by estrogen receptor β. J Steroid Biochem Mol Biol 2013; 138:455-61. [PMID: 24076016 DOI: 10.1016/j.jsbmb.2013.09.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Revised: 08/14/2013] [Accepted: 09/05/2013] [Indexed: 10/26/2022]
Abstract
In the hippocampus, synaptic proteins, as studied so far, have been shown to be upregulated by 17β-estradiol, while inhibition of local estradiol synthesis consistently downregulates them. As an exception to this rule, we have previously shown that synaptopodin, an actin-associated postsynaptic protein, is downregulated in response to estradiol in dissociated cultured hippocampal neurons. In this study, we show, unexpectedly, that synaptopodin is downregulated in the hippocampus of aromatase knock-out mice and that inhibition of neuronal estradiol synthesis using the aromatase inhibitor letrozole also downregulates synaptopodin in these cultures. Moreover, the effects of estradiol and letrozole are additive, suggesting a subtle balance between available ligand and receptor. Using selective estrogen receptor agonists and antagonists, we consequently studied the effects of estrogen receptor subtypes on synaptopodin expression in our hippocampal cultures. We found that estradiol-induced downregulation of synaptopodin is mediated by estrogen receptor β. Estrogen receptor β in turn, is upregulated in response to intracellular estradiol ablation following inhibition of estradiol synthesis by letrozole in dissociated hippocampal cultures, as well as in the hippocampus of the aromatase knock-out mouse. Thus, it appears that both the application of estradiol, via binding to estrogen receptor β, and letrozole, via upregulation of estrogen receptor β, eventually result in a downregulation of synaptopodin. Our data show that the synaptic plasticity caused by estradiol is subject to a subtle balance of the levels of estrogen receptor subtypes regulated by the available ligands. In addition, both seem to be part of a homeostatic feedback mechanism.
Collapse
Affiliation(s)
- Lars Fester
- Institute of Neuroanatomy, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Chalovich JM, Schroeter MM. Synaptopodin family of natively unfolded, actin binding proteins: physical properties and potential biological functions. Biophys Rev 2010; 2:181-189. [PMID: 28510039 PMCID: PMC5418383 DOI: 10.1007/s12551-010-0040-5] [Citation(s) in RCA: 22] [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: 09/02/2010] [Accepted: 11/01/2010] [Indexed: 12/15/2022] Open
Abstract
The synaptopodin family of proteins consists of at least 3 members: synaptopodin, the synaptopodin 2 proteins, and the synaptopodin 2-like proteins. Each family member has at least 3 isoforms that are produced by alternative splicing. Synaptopodin family members are basic proteins that are rich in proline and have little regular 2° or 3° structure at physiological temperature, pH and ionic strength. Like other natively unfolded proteins, synaptopodin family members have multiple binding partners including actin and other actin-binding proteins. Several members of the synaptopodin family have been shown to stimulate actin polymerization and to bundle actin filaments either on their own or in collaboration with other proteins. Synaptopodin 2 has been shown to accelerate nucleation of actin filament formation and to induce actin bundling. The actin polymerization activity is inhibited by Ca2+-calmodulin. Synaptopodin 2 proteins are localized in Z-bands of striated and heart muscle and dense bodies of smooth muscle cells. Depending on the developmental status and stress, at least one member of the synaptopodin family can occupy nuclei of some cells. Members of the synaptopodin 2 subfamily have been implicated in cancers.
Collapse
Affiliation(s)
- Joseph M Chalovich
- Department of Biochemistry and Molecular Biology, Brody School of Medicine at East Carolina University, 5E-122 Brody Medical Sciences Building, 600 Moye Blvd, Greenville, NC, 27834, USA.
| | - Mechthild M Schroeter
- Department of Physiology, University of Cologne, Robert-Koch-Str. 39, 50931, Cologne, Germany
| |
Collapse
|