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Bakhashab S, O’Neill J, Barber R, Arden C, Weaver JU. Upregulation of Anti-Angiogenic miR-106b-3p Correlates Negatively with IGF-1 and Vascular Health Parameters in a Model of Subclinical Cardiovascular Disease: Study with Metformin Therapy. Biomedicines 2024; 12:171. [PMID: 38255276 PMCID: PMC10813602 DOI: 10.3390/biomedicines12010171] [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: 12/24/2023] [Revised: 01/08/2024] [Accepted: 01/09/2024] [Indexed: 01/24/2024] Open
Abstract
Well-controlled type 1 diabetes mellitus (T1DM) is regarded as a model of subclinical cardiovascular disease (CVD), characterized by inflammation and adverse vascular health. However, the underlying mechanisms are not fully understood. We investigated insulin-like growth factor-1 (IGF-1) and IGF-binding protein-3 (IGFBP-3) levels, their correlation to miR-106b-3p expression in a subclinical CVD model, and the cardioprotective effect of metformin. A total of 20 controls and 29 well-controlled T1DM subjects were studied. Plasma IGF-1, IGFBP-3 levels, and miR-106b-3p expression in colony-forming unit-Hills were analyzed and compared with vascular markers. miR-106b-3p was upregulated in T1DM (p < 0.05) and negatively correlated with pro-angiogenic markers CD34+/100-lymphocytes (p < 0.05) and IGF-1 (p < 0.05). IGF-1 was downregulated in T1DM (p < 0.01), which was associated with increased inflammatory markers TNF-α, CRP, and IL-10 and reduced CD34+/100-lymphocytes. IGFBP-3 had no significant results. Metformin had no effect on IGF-1 but significantly reduced miR-106b-3p (p < 0.0001). An Ingenuity Pathway analysis predicted miR-106b-3p to inhibit PDGFA, PIK3CG, GDNF, and ADAMTS13, which activated CVD. Metformin was predicted to be cardioprotective by inhibiting miR-106b-3p. In conclusion: Subclinical CVD is characterized by a cardio-adverse profile of low IGF-1 and upregulated miR-106b-3p. We demonstrated that the cardioprotective effect of metformin may be via downregulation of upregulated miR-106b-3p and its effect on downstream targets.
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Affiliation(s)
- Sherin Bakhashab
- Biochemistry Department, King Abdulaziz University, P.O. Box 80218, Jeddah 21589, Saudi Arabia;
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; (J.O.); (R.B.)
- Center of Excellence in Genomic Medicine Research, King Abdulaziz University, P.O. Box 80216, Jeddah 21589, Saudi Arabia
| | - Josie O’Neill
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; (J.O.); (R.B.)
- Biosciences Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, UK;
| | - Rosie Barber
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; (J.O.); (R.B.)
- Biosciences Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, UK;
| | - Catherine Arden
- Biosciences Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, UK;
| | - Jolanta U. Weaver
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; (J.O.); (R.B.)
- Department of Diabetes, Queen Elizabeth Hospital, Newcastle upon Tyne NE9 6SH, UK
- Vascular Biology and Medicine Theme, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
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Lei S, Li C, She Y, Zhou S, Shi H, Chen R. Roles of super enhancers and enhancer RNAs in skeletal muscle development and disease. Cell Cycle 2023; 22:495-505. [PMID: 36184878 PMCID: PMC9928468 DOI: 10.1080/15384101.2022.2129240] [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] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 09/09/2022] [Accepted: 09/21/2022] [Indexed: 11/03/2022] Open
Abstract
Skeletal muscle development is a multistep biological process regulated by a variety of myogenic regulatory factors, including MyoG, MyoD, Myf5, and Myf6 (also known as MRF4), as well as members of the FoxO subfamily. Differentiation and regeneration during skeletal muscle myogenesis contribute to the physiological function of muscles. Super enhancers (SEs) and enhancer RNAs (eRNAs) are involved in the regulation of development and diseases. Few studies have identified the roles of SEs and eRNAs in muscle development and pathophysiology. To develop approaches to enhance skeletal muscle mass and function, a more comprehensive understanding of the key processes underlying muscular diseases is needed. In this review, we summarize the roles of SEs and eRNAs in muscle development and disease through affecting of DNA methylation, FoxO subfamily, RAS-MEK signaling, chromatin modifications and accessibility, MyoD and cis regulating target genes. The summary could inform strategies to increase muscle mass and treat muscle-related diseases.
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Affiliation(s)
- Si Lei
- Guangdong Second Provincial General Hospital, Guangdong Traditional Medical and Sports Injury Rehabilitation Research Institute, Guangzhou, China
| | - Cheng Li
- Guangdong Second Provincial General Hospital, Guangdong Traditional Medical and Sports Injury Rehabilitation Research Institute, Guangzhou, China
| | - Yanling She
- Guangdong Second Provincial General Hospital, Guangdong Traditional Medical and Sports Injury Rehabilitation Research Institute, Guangzhou, China
| | - Shanyao Zhou
- Guangdong Second Provincial General Hospital, Guangdong Traditional Medical and Sports Injury Rehabilitation Research Institute, Guangzhou, China
| | - Huacai Shi
- Guangdong Second Provincial General Hospital, Guangdong Traditional Medical and Sports Injury Rehabilitation Research Institute, Guangzhou, China
| | - Rui Chen
- Guangdong Second Provincial General Hospital, Guangdong Traditional Medical and Sports Injury Rehabilitation Research Institute, Guangzhou, China
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Bacos K, Perfilyev A, Karagiannopoulos A, Cowan E, Ofori JK, Bertonnier-Brouty L, Rönn T, Lindqvist A, Luan C, Ruhrmann S, Ngara M, Nilsson Å, Gheibi S, Lyons CL, Lagerstedt JO, Barghouth M, Esguerra JL, Volkov P, Fex M, Mulder H, Wierup N, Krus U, Artner I, Eliasson L, Prasad RB, Cataldo LR, Ling C. Type 2 diabetes candidate genes, including PAX5, cause impaired insulin secretion in human pancreatic islets. J Clin Invest 2023; 133:163612. [PMID: 36656641 PMCID: PMC9927941 DOI: 10.1172/jci163612] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [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: 07/15/2022] [Accepted: 01/05/2023] [Indexed: 01/20/2023] Open
Abstract
Type 2 diabetes (T2D) is caused by insufficient insulin secretion from pancreatic β cells. To identify candidate genes contributing to T2D pathophysiology, we studied human pancreatic islets from approximately 300 individuals. We found 395 differentially expressed genes (DEGs) in islets from individuals with T2D, including, to our knowledge, novel (OPRD1, PAX5, TET1) and previously identified (CHL1, GLRA1, IAPP) candidates. A third of the identified expression changes in islets may predispose to diabetes, as expression of these genes associated with HbA1c in individuals not previously diagnosed with T2D. Most DEGs were expressed in human β cells, based on single-cell RNA-Seq data. Additionally, DEGs displayed alterations in open chromatin and associated with T2D SNPs. Mouse KO strains demonstrated that the identified T2D-associated candidate genes regulate glucose homeostasis and body composition in vivo. Functional validation showed that mimicking T2D-associated changes for OPRD1, PAX5, and SLC2A2 impaired insulin secretion. Impairments in Pax5-overexpressing β cells were due to severe mitochondrial dysfunction. Finally, we discovered PAX5 as a potential transcriptional regulator of many T2D-associated DEGs in human islets. Overall, we have identified molecular alterations in human pancreatic islets that contribute to β cell dysfunction in T2D pathophysiology.
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Affiliation(s)
- Karl Bacos
- Epigenetics and Diabetes Unit, Department of Clinical Sciences and
| | | | - Alexandros Karagiannopoulos
- Unit of Islet Cell Exocytosis, Department of Clinical Sciences, Lund University Diabetes Centre, Scania University Hospital, Malmö, Scania, Sweden
| | - Elaine Cowan
- Unit of Islet Cell Exocytosis, Department of Clinical Sciences, Lund University Diabetes Centre, Scania University Hospital, Malmö, Scania, Sweden
| | - Jones K. Ofori
- Epigenetics and Diabetes Unit, Department of Clinical Sciences and
| | - Ludivine Bertonnier-Brouty
- Endocrine Cell Differentiation, Department of Laboratory Medicine, Lund Stem Cell Center, Malmö, Scania, Sweden
| | - Tina Rönn
- Epigenetics and Diabetes Unit, Department of Clinical Sciences and
| | - Andreas Lindqvist
- Neuroendocrine Cell Biology, Department of Experimental Medical Science
| | - Cheng Luan
- Unit of Islet Pathophysiology, Department of Clinical Sciences
| | - Sabrina Ruhrmann
- Epigenetics and Diabetes Unit, Department of Clinical Sciences and
| | - Mtakai Ngara
- Neuroendocrine Cell Biology, Department of Experimental Medical Science
| | - Åsa Nilsson
- Human Tissue Lab, Department of Clinical Sciences
| | - Sevda Gheibi
- Molecular Metabolism Unit, Department of Clinical Sciences, and
| | - Claire L. Lyons
- Molecular Metabolism Unit, Department of Clinical Sciences, and
| | - Jens O. Lagerstedt
- Unit of Islet Cell Exocytosis, Department of Clinical Sciences, Lund University Diabetes Centre, Scania University Hospital, Malmö, Scania, Sweden
| | | | - Jonathan L.S. Esguerra
- Unit of Islet Cell Exocytosis, Department of Clinical Sciences, Lund University Diabetes Centre, Scania University Hospital, Malmö, Scania, Sweden
| | - Petr Volkov
- Epigenetics and Diabetes Unit, Department of Clinical Sciences and
| | - Malin Fex
- Molecular Metabolism Unit, Department of Clinical Sciences, and
| | - Hindrik Mulder
- Molecular Metabolism Unit, Department of Clinical Sciences, and
| | - Nils Wierup
- Neuroendocrine Cell Biology, Department of Experimental Medical Science
| | - Ulrika Krus
- Human Tissue Lab, Department of Clinical Sciences
| | - Isabella Artner
- Endocrine Cell Differentiation, Department of Laboratory Medicine, Lund Stem Cell Center, Malmö, Scania, Sweden
| | - Lena Eliasson
- Unit of Islet Cell Exocytosis, Department of Clinical Sciences, Lund University Diabetes Centre, Scania University Hospital, Malmö, Scania, Sweden
| | - Rashmi B. Prasad
- Genomics, Diabetes and Endocrinology, Department of Clinical Sciences, Lund University Diabetes Centre, Scania University Hospital, Malmö, Scania, Sweden.,Institute of Molecular Medicine (FIMM), Helsinki University, Helsinki, Finland
| | - Luis Rodrigo Cataldo
- Molecular Metabolism Unit, Department of Clinical Sciences, and,The Novo Nordisk Foundation Centre for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Charlotte Ling
- Epigenetics and Diabetes Unit, Department of Clinical Sciences and
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Jin B, Bai X, Yu K, Han L, Wang N, Han W. Reduced IGFBP-2 related immunoreactivity in human serum correlates with arterial stiffness in a healthy Chinese population. Microvasc Res 2022; 144:104423. [PMID: 35995234 DOI: 10.1016/j.mvr.2022.104423] [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] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Revised: 08/08/2022] [Accepted: 08/17/2022] [Indexed: 11/18/2022]
Abstract
BACKGROUND Circulating insulin-like growth factor binding protein 2 (IGFBP-2) is associated with metabolic changes in both physiological and pathological conditions. The aim of this study was to investigate the correlation between IGFBP-2 related immunoreactivity in serum and arterial stiffness in a healthy Chinese population. METHODS In this cross-sectional study, 360 healthy participants aged 37-87 years were recruited from 1500 and were divided into three groups according to serum IGFBP-2 related immunoreactivity (Tertile I, 25.437 ng/ml-120.870 ng/ml; Tertile II, 120.871 ng/ml-161.914 ng/ml; Tertile III, 161.915 ng/ml-321.636 ng/ml). Arterial stiffness was evaluated by measuring the brachial-ankle pulse wave velocity (baPWV), ankle-brachial index (ABI), and carotid intima-media thickness (cIMT). The association between IGFBP-2 related immunoreactivity and arterial stiffness was estimated by multiple stepwise regression. RESULTS Compared with the other two groups population, the individuals in Tertile I had significantly older age (62.66 ± 13.30 years, P < 0.01), lower level of triglyceride (1.08 ± 0.70 mmol/l, P < 0.01) and E/A (peak velocity of early filling and preak velocity of atrial filling ratio) (0.90 ± 0.33, P < 0.05). IGFBP-2 related immunoreactivity was inversely related with baPWV in the total population (r = -0.171, P < 0.01) and in Tertile I (r = -0.275, P < 0.01). After adjusting for age and the other confounders, no association was found between IGFBP-2 related immunoreactivity and baPWV in the total population. However, In Tertile I, reduced IGFBP-2 related immunoreactivity in serum was an independent risk factor of baPWV acceleration in three different adjustment models: Model 1 (no adjustment, P < 0.01), Model 2 (adjusted for age, P < 0.05), and Model 3 (adjusted for all variables, P < 0.05). CONCLUSION IGFBP-2 related immunoreactivity in serum is inversely associated with baPWV in a healthy Chinese population. This association did not change after adjustment for conventional risk factors for cardiovascular diseases in the subjects with the lowest IGFBP-2 related immunoreactivity. Consequently, reduction of IGFBP-2 related immunoreactivity may be a predictor of arterial stiffness. IGFBP-2 seems to be a potential intervention target in early atherosclerosis.
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Affiliation(s)
- Bo Jin
- Department of Gerontology and Geriatrics, The Second Hospital of Dalian Medical University, Dalian, China; Department of Gerontology and Geriatrics, Shengjing Hospital of China Medical University, Shenyang, China
| | - Xiaojuan Bai
- Department of Gerontology and Geriatrics, Shengjing Hospital of China Medical University, Shenyang, China.
| | - Kai Yu
- Department of General Medicine, The First Hospital of China Medical University, Shenyang, China
| | - Lulu Han
- Department of Gerontology and Geriatrics, Shengjing Hospital of China Medical University, Shenyang, China
| | - Nan Wang
- Department of Gerontology and Geriatrics, Shengjing Hospital of China Medical University, Shenyang, China
| | - Wen Han
- Department of Gerontology and Geriatrics, Shengjing Hospital of China Medical University, Shenyang, China
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Koucheki R, Gazendam AM, Perera JR, Griffin A, Ferguson P, Wunder J, Tsoi K. Assessment of Risk of Bias in Osteosarcoma and Ewing's Sarcoma Randomized Controlled Trials: A Systematic Review. Curr Oncol 2021; 28:3771-94. [PMID: 34677240 DOI: 10.3390/curroncol28050322] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [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: 08/17/2021] [Revised: 09/14/2021] [Accepted: 09/23/2021] [Indexed: 12/03/2022] Open
Abstract
Aim: The aim of this study was to systematically assess the risk of bias in osteosarcoma and Ewing’s sarcoma (ES) randomized controlled trials (RCT) and to examine the relationships between bias and conflict of interest/industry sponsorship. Methods: An OVID-MEDLINE search was performed (1976–2019). Using the Cochrane Collaboration guidelines, two reviewers independently assessed the prevalence of risk of bias in different RCT design domains. The relationship between conflicts of interest and industry funding with the frequency of bias was examined. Results: 73 RCTs met inclusion criteria. Prevalence of low-risk bias domains was 47.3%, unclear-risk domains 47.8%, and 4.9% of the domains had a high-risk of bias. Domains with the highest risk of bias were blinding of participants/personnel and outcome assessors, followed by randomization and allocation concealment. Overtime, frequency of unclear-risk of bias domains decreased (χ2 = 5.32, p = 0.02), whilst low and high-risk domains increased (χ2 = 8.13, p = 0.004). Studies with conflicts of interest and industry sponsorships were 4.2 and 3.1 times more likely to have design domains with a high-risk of bias (p < 0.05). Conclusion: This study demonstrates that sources of potential bias are prevalent in both osteosarcoma and ES RCTs. Studies with financial conflicts of interest and industry sponsors were significantly more likely to have domains with a high-risk of bias. Improvements in reporting and adherence to proper methodology will reduce the risk of bias and improve the validity of the results of RCTs in osteosarcoma and ES.
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Janssen JAMJL, Varewijck AJ, Brugts MP. The insulin-like growth factor-I receptor stimulating activity (IRSA) in health and disease. Growth Horm IGF Res 2019; 48-49:16-28. [PMID: 31493625 DOI: 10.1016/j.ghir.2019.08.001] [Citation(s) in RCA: 8] [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] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 07/26/2019] [Accepted: 08/19/2019] [Indexed: 10/26/2022]
Abstract
Determination of true IGF-I bioactivity in serum and other biological fluids is still a substantial challenge. The IGF-IR Kinase Receptor Activation assay (IGF-IR KIRA assay) is a novel tool to asses IGF-IR stimulating activity (IRSA) and has opened a new era in studying the IGF system. In this paper we discuss many studies showing that measuring IRSA by the IGF-IR KIRA assay often provides fundamentally different information about the IGF system than the commonly used total IGF-I immunoassays. With the IGF-IR KIRA assay phosphorylation of tyrosine residues of the IGF-IR is used as read out to quantify IRSA in unknown (serum) samples. The IGF-IR KIRA assay gives information about net overall effects of circulating IGF-I, IGF-II, IGFBPs and IGFBP-proteases on IGF-IR activation and seems especially superior to immunoreactive total IGF-I in monitoring therapeutic interventions. Although the IRSA as measured by the IGF-IR KIRA assay probably more closely reflects true bioactive IGF-I than measurements of total IGF-I in serum, the IGF-IR KIRA assay in its current form does not give information about all the post-receptor intracellular events mediated by the IGF-IR. Interestingly, in several conditions in health and disease IRSA measured by the IGF-IR KIRA assay is considerably higher in interstitial fluid and ascites than in serum. This suggests that both the paracrine (local) and endocrine (circulating) IRSA should be measured to get a complete picture about the role of the IGF system in health and disease.
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Affiliation(s)
- Joseph A M J L Janssen
- Department of Internal Medicine, Division of Endocrinology, Erasmus MC, Rotterdam, the Netherlands.
| | - Aimee J Varewijck
- Department of Internal Medicine, Division of Endocrinology, Erasmus MC, Rotterdam, the Netherlands
| | - Michael P Brugts
- Department of Internal Medicine, Ikazia Hospital, Rotterdam, the Netherlands
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Abstract
PURPOSE OF REVIEW We review studies demonstrating lowered levels of insulin-like growth factors (IGFs) in patients with recent-onset type 1 diabetes (T1D) and discuss their potential roles in the disorder's pathogenesis. RECENT FINDINGS IGFs have long been recognized as a class of hormones that promote growth, development, and cellular metabolism throughout the human body. More recently, studies have noted an association between reduced pancreatic weight/volume and T1D. Thus, we believe it is important to understand pancreatic regulation of IGF expression and bioavailability, as well as the impact of IGFs on pancreatic growth and islet health. Additional studies of IGFs have been extended to their influence on the inflammatory/regulatory balance of monocytes, B cells, and T cells; features which have been previously established to show dysregulation in settings of T1D. SUMMARY These data suggest that IGFs may prevent known impairments in the pancreas and immune system in T1D and underscore the need to extend these studies, some of which were performed in health or other autoimmune diseases, toward T1D specifically. Collectively, the work emphasized here support the potential therapeutic use of IGFs in T1D prevention efforts as pancreatic growth factors and/or immunoregulatory agents.
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Affiliation(s)
- Melanie R. Shapiro
- Department of Pathology, Immunology, and Laboratory Medicine, The University of Florida Diabetes Institute, Gainesville, Florida, USA
| | - Mark A. Atkinson
- Department of Pathology, Immunology, and Laboratory Medicine, The University of Florida Diabetes Institute, Gainesville, Florida, USA
- Department of Pediatrics, The University of Florida Diabetes Institute, Gainesville, Florida, USA
| | - Todd M. Brusko
- Department of Pathology, Immunology, and Laboratory Medicine, The University of Florida Diabetes Institute, Gainesville, Florida, USA
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Similä ME, Kontto JP, Virtamo J, Hätönen KA, Valsta LM, Sundvall J, Männistö S. Insulin-like growth factor I, binding proteins -1 and -3, risk of type 2 diabetes and macronutrient intakes in men. Br J Nutr 2019; 121:938-44. [PMID: 30898176 DOI: 10.1017/S0007114519000321] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The insulin-like growth factor (IGF) axis may be involved in the development of type 2 diabetes. We examined the associations of IGF-I and IGF binding proteins (IGFBP)-1 and -3 with diabetes risk and evaluated macronutrient intakes related to the observed associations. In a nested case-control study of the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study of Finnish male smokers aged 50-69 years, the IGF variables were measured from baseline serum samples for a random sample of 310 men with diabetes diagnosed during a 12-year follow-up and for 310 controls matched by age, recruitment day and intervention group. Diet at baseline was assessed using a validated FFQ. The associations of IGF proteins with diabetes risk were estimated using conditional logistic regression and the associations with macronutrient intakes using linear regression. IGF-I and IGFBP-3 were not associated with the incidence of diabetes. Higher IGFBP-1 was associated with lower diabetes risk in an unadjusted crude model (OR 0·25; 95 % CI 0·15, 0·42 in the highest quartile compared with the lowest), but not after adjustment for BMI (corresponding OR 0·76; 95 % CI 0·41, 1·40). Intakes of carbohydrates, plant protein and milk protein associated positively and intake of meat protein and fat negatively with IGFBP-1 (P<0·005). IGFBP-1 was inversely associated with diabetes risk, but the association was substantially dependent on BMI. The associations between macronutrient intakes and IGFBP-1 may reflect influences of nutrients or foods on insulin concentrations.
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Bai J, Jiang X, He M, Chan BCB, Wong AOL. Novel Mechanisms for IGF-I Regulation by Glucagon in Carp Hepatocytes: Up-Regulation of HNF1α and CREB Expression via Signaling Crosstalk for IGF-I Gene Transcription. Front Endocrinol (Lausanne) 2019; 10:605. [PMID: 31551932 PMCID: PMC6734168 DOI: 10.3389/fendo.2019.00605] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 08/20/2019] [Indexed: 12/13/2022] Open
Abstract
Glucagon, a key hormone for glucose homeostasis, can exert functional crosstalk with somatotropic axis via modification of IGF-I expression. However, its effect on IGF-I regulation is highly variable in different studies and the mechanisms involved are largely unknown. Using grass carp as a model, the signal transduction and transcriptional mechanisms for IGF-I regulation by glucagon were examined in Cyprinid species. As a first step, the carp HNF1α, a liver-enriched transcription factor, was cloned and confirmed to be a single-copy gene expressed in the liver. In grass carp hepatocytes, glucagon treatment could elevate IGF-I, HNF1α, and CREB mRNA levels, induce CREB phosphorylation, and up-regulate HNF1α and CREB protein expression. The effects on IGF-I, HNF1α, and CREB gene expression were mediated by cAMP/PKA and PLC/IP3/PKC pathways with differential coupling with the MAPK and PI3K/Akt cascades. During the process, protein:protein interaction between HNF1α and CREB and recruitment of RNA Pol-II to IGF-I promoter also occurred with a rise in IGF-I primary transcript level. In parallel study to examine grass carp IGF-I promoter activity expressed in αT3 cells, similar pathways for post-receptor signaling were also confirmed in glucagon-induced IGF-I promoter activation and the trans-activating effect by glucagon was mediated by the binding sites for HNF1α and CREB located in the proximal region of IGF-I promoter. Our findings, as a whole, shed light on a previously undescribed mechanism for glucagon-induced IGF-I gene expression by increasing HNF1α and CREB production via functional crosstalk of post-receptor signaling. Probably, by protein:protein interaction between the two transcription factors and subsequent transactivation via their respective cis-acting elements in the IGF-I promoter, IGF-I gene transcription can be initiated by glucagon at the hepatic level.
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