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Qin P, Zhou P, Huang Y, Long B, Gao R, Zhang S, Zhu B, Li YQ, Li Q. Upregulation of rate-limiting enzymes in cholesterol metabolism by PKCδ mediates endothelial apoptosis in diabetic wound healing. Cell Death Discov 2024; 10:263. [PMID: 38811564 PMCID: PMC11137154 DOI: 10.1038/s41420-024-02030-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 05/03/2024] [Accepted: 05/14/2024] [Indexed: 05/31/2024] Open
Abstract
Diabetic foot ulcer (DFU) is a prevalent complication of diabetes that poses significant challenges in terms of treatment and management. It is characterized by heightened endothelial apoptosis and impaired angiogenesis. In this study, we aimed to investigate the role of protein kinase Cδ (PKCδ) in regulating endothelial apoptosis in diabetic wounds by promoting cholesterol biosynthesis. The expression of PKCδ was increased in human umbilical vascular endothelial cells (HUVECs) cultivated in high glucose medium and skin tissue isolated from diabetic mice. High glucose-induced HUVECs apoptosis was reduced by PKCδ inhibition with siRNA or rottlerin. RNA-seq identified two enzymes, 3-hydroxy-3-methylglutaryl-CoA synthase 1 (HMGCS1) and 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), as the downstream of PKCδ. PKCδ knockdown or inhibition suppressed the expression of HMGCS1 and HMGCR and lowered free cholesterol (FC) levels. Cholesterol restored high glucose-induced apoptosis in siRNA- or rottlerin-treated HUVECs. In vivo use of rosuvastatin calcium, an inhibitor of HMGCR, downregulated free cholesterol levels and accelerated the wound healing process. In conclusion, PKCδ expression in endothelial cells was activated by high glucose, which subsequently upregulates the expression of two enzymes catalyzing cholesterol biosynthesis, HMGCS1 and HMGCR. Enhanced cholesterol biosynthesis raises free cholesterol levels, promotes endothelial apoptosis, and finally delays wound healing.
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Affiliation(s)
- Peiliang Qin
- Department of Vascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Peng Zhou
- Department of Vascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Yating Huang
- Department of Vascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Binbin Long
- General Surgery Department, Taihe Hospital Affiliated to Hubei University of Medicine, Shiyan, Hubei, China
| | - Ruikang Gao
- Department of Vascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Shan Zhang
- Department of Vascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Bingjie Zhu
- Department of Vascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Yi-Qing Li
- Department of Vascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
| | - Qin Li
- Department of Vascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
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2
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Maurotti S, Pujia R, Galluccio A, Nucera S, Musolino V, Mare R, Frosina M, Noto FR, Mollace V, Romeo S, Pujia A, Montalcini T. Preventing muscle wasting: pro-insulin C-peptide prevents loss in muscle mass in streptozotocin-diabetic rats. J Cachexia Sarcopenia Muscle 2023; 14:1117-1129. [PMID: 36878894 PMCID: PMC10067479 DOI: 10.1002/jcsm.13210] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 12/01/2022] [Accepted: 02/07/2023] [Indexed: 03/08/2023] Open
Abstract
BACKGROUND C-peptide therapy exerts several positive actions on nerves, vasculature, smooth muscle relaxation, kidney function and bone. To date, the role of C-peptide in preventing type 1 diabetes-related muscle atrophy has not been investigated. Our aim was to evaluate if C-peptide infusion prevents muscle wasting in diabetic rats. METHODS Twenty-three male Wistar rats were randomly divided into three groups: normal control group, diabetic group and diabetic group plus C-peptide. Diabetes was induced by streptozotocin injection, and C-peptide was administered subcutaneously for 6 weeks. The blood samples were obtained at baseline, before streptozotocin injection and at the end of the study to assess C-peptide, ubiquitin and other laboratory parameters. We also tested the ability of C-peptide to regulate the skeletal muscle mass, the ubiquitin-proteasome system, the autophagy pathway as well as to improve muscle quality. RESULTS C-peptide administration reversed hyperglycaemia (P = 0.02) and hypertriglyceridaemia (P = 0.01) in diabetic plus C-peptide rats compared with diabetic control rats. The diabetic-control animals displayed a lower weight of the muscles in the lower limb considered individually than the control rats and the diabetic plus C-peptide rats (P = 0.03; P = 0.03; P = 0.04; P = 0.004, respectively). The diabetic-control rats presented a significantly higher serum concentration of ubiquitin compared with the diabetic plus C-peptide and the control animals (P = 0.02 and P = 0.01). In muscles of the lower limb, the pAmpk expression was higher in the diabetic plus C-peptide than the diabetic-control rats (in the gastrocnemius, P = 0.002; in the tibialis anterior P = 0.005). The protein expression of Atrogin-1 in gastrocnemius and tibialis was lower in the diabetic plus C-peptide than in diabetic-control rats (P = 0.02, P = 0.03). After 42 days, the cross-sectional area in the gastrocnemius of the diabetic plus C-peptide group had been reduced by 6.6% while the diabetic-control rats had a 39.5% reduction compared with the control animals (P = 0.02). The cross-sectional area of the tibialis and the extensor digitorum longus muscles was reduced, in the diabetic plus C-peptide rats, by 10% and 11%, respectively, while the diabetic-control group had a reduction of 65% and 45% compared with the control animals (both P < 0.0001). Similar results were obtained for the minimum Feret's diameter and perimeter. CONCLUSIONS C-peptide administration in rats could protect skeletal muscle mass from atrophy induced by type 1 diabetes mellitus. Our findings could suggest that targeting the ubiquitin-proteasome system, Ampk and muscle-specific E3 ubiquitin ligases such as Atrogin-1 and Traf6 may be an effective strategy for molecular and clinical intervention in the muscle wasting pathological process in T1DM.
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Affiliation(s)
- Samantha Maurotti
- Department of Clinical and Experimental Medicine, University Magna Graecia, Catanzaro, Italy
| | - Roberta Pujia
- Department of Medical and Surgical Science, University Magna Graecia, Catanzaro, Italy
| | - Angelo Galluccio
- Department of Clinical and Experimental Medicine, University Magna Graecia, Catanzaro, Italy
| | - Saverio Nucera
- Department of Health Science, University Magna Graecia, Catanzaro, Italy
| | - Vincenzo Musolino
- Department of Health Science, University Magna Graecia, Catanzaro, Italy
| | - Rosario Mare
- Department of Clinical and Experimental Medicine, University Magna Graecia, Catanzaro, Italy
| | - Miriam Frosina
- Department of Medical and Surgical Science, University Magna Graecia, Catanzaro, Italy
| | - Francesca Rita Noto
- Department of Medical and Surgical Science, University Magna Graecia, Catanzaro, Italy
| | - Vincenzo Mollace
- Department of Health Science, University Magna Graecia, Catanzaro, Italy
| | - Stefano Romeo
- Department of Medical and Surgical Science, University Magna Graecia, Catanzaro, Italy.,Department of Molecular and Clinical Medicine, University of Gothenburg, Gothenburg, Sweden
| | - Arturo Pujia
- Department of Medical and Surgical Science, University Magna Graecia, Catanzaro, Italy.,Research Center for the Prevention and Treatment of Metabolic Diseases (CR METDIS), University Magna Graecia, Catanzaro, Italy
| | - Tiziana Montalcini
- Department of Clinical and Experimental Medicine, University Magna Graecia, Catanzaro, Italy.,Research Center for the Prevention and Treatment of Metabolic Diseases (CR METDIS), University Magna Graecia, Catanzaro, Italy
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3
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Rossiter JL, Redlinger LJ, Kolar GR, Samson WK, Yosten GLC. The actions of C-peptide in HEK293 cells are dependent upon insulin and extracellular glucose concentrations. Peptides 2022; 150:170718. [PMID: 34954230 DOI: 10.1016/j.peptides.2021.170718] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 12/15/2021] [Accepted: 12/17/2021] [Indexed: 10/19/2022]
Abstract
Connecting peptide, or C-peptide, is a part of the insulin prohormone and is essential for the proper folding and processing of the mature insulin peptide. C-peptide is released from the same beta cell secretory granules as insulin in equimolar amounts. However, due to their relative stabilities in plasma, the two peptides are detected in the circulation at ratios of approximately 4:1 to 6:1 (C-peptide to insulin), depending on metabolic state. C-peptide binds specifically to human cell membranes and induces intracellular signaling cascades, likely through an interaction with the G protein coupled receptor, GPR146. C-peptide has been shown to exert protective effects against the vascular, renal, and ocular complications of diabetes. The effects of C-peptide appear to be dependent upon the presence of insulin and the absolute, extracellular concentration of glucose. In this study, we employed HEK293 cells to further examine the interactive effects of C-peptide, insulin, and glucose on cell signaling. We observed that C-peptide's cellular effects are dampened significantly when cells are exposed to physiologically relevant concentrations of both insulin and C-peptide. Likewise, the actions of C-peptide on cFos and GPR146 mRNA expressions were affected by changes in extracellular glucose concentration. In particular, C-peptide induced significant elevations in cFos expression in the setting of high (25 mmol) extracellular glucose concentration. These data indicate that future experimentation on the actions of C-peptide should control for the presence or absence of insulin and the concentration of glucose. Furthermore, these findings should be considered prior to the development of C-peptide-based therapeutics for the treatment of diabetes-associated complications.
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Affiliation(s)
- Jacqueline L Rossiter
- Department of Pharmacology and Physiology, Saint Louis University School of Medicine, 1402 S. Grand Boulevard, Saint Louis, MO 63104, United States
| | - Lauren J Redlinger
- Department of Pharmacology and Physiology, Saint Louis University School of Medicine, 1402 S. Grand Boulevard, Saint Louis, MO 63104, United States
| | - Grant R Kolar
- Department of Pathology, Saint Louis University School of Medicine, 1402 S. Grand Boulevard, Saint Louis, MO 63104, United States
| | - Willis K Samson
- Department of Pharmacology and Physiology, Saint Louis University School of Medicine, 1402 S. Grand Boulevard, Saint Louis, MO 63104, United States
| | - Gina L C Yosten
- Department of Pharmacology and Physiology, Saint Louis University School of Medicine, 1402 S. Grand Boulevard, Saint Louis, MO 63104, United States.
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Vejrazkova D, Vankova M, Lukasova P, Vcelak J, Bendlova B. Insights into the physiology of C-peptide. Physiol Res 2021; 69:S237-S243. [PMID: 33094622 DOI: 10.33549/physiolres.934519] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Current knowledge suggests a complex role of C-peptide in human physiology, but its mechanism of action is only partially understood. The effects of C-peptide appear to be variable depending on the target tissue, physiological environment, its combination with other bioactive molecules such as insulin, or depending on its concentration. It is apparent that C-peptide has therapeutic potential for the treatment of vascular and nervous damage caused by type 1 or late type 2 diabetes mellitus. The question remains whether the effect is mediated by the receptor, the existence of which is still uncertain, or whether an alternative non-receptor-mediated mechanism is responsible. The Institute of Endocrinology in Prague has been paying much attention to the issue of C-peptide and its metabolic effect since the 1980s. The RIA methodology of human C-peptide determination was introduced here and transferred to commercial production. By long-term monitoring of C-peptide oGTT-derived indices, the Institute has contributed to elucidating the pathophysiology of glucose tolerance disorders. This review summarizes the current knowledge of C-peptide physiology and highlights the contributions of the Institute of Endocrinology to this issue.
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Affiliation(s)
- D Vejrazkova
- Department of Molecular Endocrinology, Institute of Endocrinology, Prague, Czech Republic.
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5
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Luo J, Jiang J, Huang H, Jiang F, Xu Z, Zhou Z, Zhu H. C-peptide ameliorates high glucose-induced podocyte dysfunction through the regulation of the Notch and TGF-β signaling pathways. Peptides 2021; 142:170557. [PMID: 33901627 DOI: 10.1016/j.peptides.2021.170557] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 04/15/2021] [Accepted: 04/16/2021] [Indexed: 12/25/2022]
Abstract
The podocyte is one of the main components of the glomerular filtration barrier in the kidney, and its injury may contribute to proteinuria, glomerulosclerosis and eventually kidney failure. C-peptide, a cleavage product of proinsulin, shows therapeutic potential for treating diabetic nephropathy (DN). The aim of this study was to investigate the effect of C-peptide on high glucose-induced podocyte dysfunction. In the present study, we found that the protective effects of islet transplantation were superior to simple insulin therapy for the treatment of DN in streptozotocin (STZ)-treated rats. And such superiority may due to the function of C-peptide secreted at the implanted site. Based on this background, we determined that the application of C-peptide significantly prevented high glucose-induced podocyte injury by increasing the expression of nephrin and synaptopodin. Meanwhile, C-peptide suppressed high glucose-induced epithelial-mesenchymal transition (EMT) and renal fibrosis via decreasing the expression of snail, vimentin, α-smooth muscle actin (α-SMA) and connective tissue growth factor (CTGF). Moreover, the Notch and transforming growth factor-β (TGF-β) signaling pathways were activated by high glucose, and treatment with C-peptide down-regulated the expression of the Notch signaling molecules Notch 1 and Jagged 1 and the TGF-β signaling molecule TGF-β1. These findings suggested that C-peptide might serve as a novel treatment method for DN and podocyte dysfunction.
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Affiliation(s)
- Jiao Luo
- Department of Laboratory Medicine, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, 310003, China
| | - Jiahong Jiang
- Department of Endocrinology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325000, China
| | - Hongjian Huang
- Department of Hepatobiliary Surgery, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325000, China
| | - Feifei Jiang
- Department of Endocrinology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325000, China
| | - Zeru Xu
- Department of Endocrinology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325000, China
| | - Zijun Zhou
- Department of Endocrinology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325000, China
| | - Hong Zhu
- Department of Endocrinology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325000, China.
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Nepal N, Arthur S, Butts MR, Singh S, Palaniappan B, Sundaram U. Molecular Mechanism of Stimulation of Na-K-ATPase by Leukotriene D4 in Intestinal Epithelial Cells. Int J Mol Sci 2021; 22:ijms22147569. [PMID: 34299188 PMCID: PMC8303499 DOI: 10.3390/ijms22147569] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Revised: 07/02/2021] [Accepted: 07/07/2021] [Indexed: 12/03/2022] Open
Abstract
Na-K-ATPase provides a favorable transcellular Na gradient required for the functioning of Na-dependent nutrient transporters in intestinal epithelial cells. The primary metabolite for enterocytes is glutamine, which is absorbed via Na-glutamine co-transporter (SN2; SLC38A5) in intestinal crypt cells. SN2 activity is stimulated during chronic intestinal inflammation, at least in part, secondarily to the stimulation of Na-K-ATPase activity. Leukotriene D4 (LTD4) is known to be elevated in the mucosa during chronic enteritis, but the way in which it may regulate Na-K-ATPase is not known. In an in vitro model of rat intestinal epithelial cells (IEC-18), Na-K-ATPase activity was significantly stimulated by LTD4. As LTD4 mediates its action via Ca-dependent protein kinase C (PKC), Ca levels were measured and were found to be increased. Phorbol 12-myristate 13-acetate (PMA), an activator of PKC, also mediated stimulation of Na-K-ATPase like LTD4, while BAPTA-AM (Ca chelator) and calphostin-C (Cal-C; PKC inhibitor) prevented the stimulation of Na-K-ATPase activity. LTD4 caused a significant increase in mRNA and plasma membrane protein expression of Na-K-ATPase α1 and β1 subunits, which was prevented by calphostin-C. These data demonstrate that LTD4 stimulates Na-K-ATPase in intestinal crypt cells secondarily to the transcriptional increase of Na-K-ATPase α1 and β1 subunits, mediated via the Ca-activated PKC pathway.
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7
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Biological Activity of c-Peptide in Microvascular Complications of Type 1 Diabetes-Time for Translational Studies or Back to the Basics? Int J Mol Sci 2020; 21:ijms21249723. [PMID: 33419247 PMCID: PMC7766542 DOI: 10.3390/ijms21249723] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 12/15/2020] [Accepted: 12/16/2020] [Indexed: 12/15/2022] Open
Abstract
People with type 1 diabetes have an increased risk of developing microvascular complications, which have a negative impact on the quality of life and reduce life expectancy. Numerous studies in animals with experimental diabetes show that c-peptide supplementation exerts beneficial effects on diabetes-induced damage in peripheral nerves and kidneys. There is substantial evidence that c-peptide counteracts the detrimental changes caused by hyperglycemia at the cellular level, such as decreased activation of endothelial nitric oxide synthase and sodium potassium ATPase, and increase in formation of pro-inflammatory molecules mediated by nuclear factor kappa-light-chain-enhancer of activated B cells: cytokines, chemokines, cell adhesion molecules, vascular endothelial growth factor, and transforming growth factor beta. However, despite positive results from cell and animal studies, no successful c-peptide replacement therapies have been developed so far. Therefore, it is important to improve our understanding of the impact of c-peptide on the pathophysiology of microvascular complications to develop novel c-peptide-based treatments. This article aims to review current knowledge on the impact of c-peptide on diabetic neuro- and nephropathy and to evaluate its potential therapeutic role.
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8
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Cui P, Chen Y, Waili N, Li Y, Ma C, Li Y. Associations of serum C-peptide and insulin-like growth factor binding proteins-3 with breast cancer deaths. PLoS One 2020; 15:e0242310. [PMID: 33180852 PMCID: PMC7660502 DOI: 10.1371/journal.pone.0242310] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 10/31/2020] [Indexed: 12/22/2022] Open
Abstract
C-peptide is usually considered as a marker of insulin secretion and has no physiological function. This study aimed to assess the association between serum C-peptide level as independent risk factor and breast cancer and explored the possible underlying mechanisms. This was a population-based cohort study. All the data was collected according to a standard protocol. The C-peptide and insulin-like growth factor binding proteins-3(IGFBP-3) concentrations were measured in blood. The breast cancer deaths were confirmed by National Death Index records. Cox proportional hazard regression analysis was conducted to determine the hazard ratio of serum C-peptide level for breast cancer deaths. Analysis of covariance was used to assess the association between serum C-peptide and IGFBP-3 level, and the linear trend was tested by using a linear model. A total of 8,373 women 17 years of age or older were included in the study, and 57 breast cancer deaths were observed over the study period. The result of survival analysis showed that breast cancer deaths increased with increasing levels of serum C-peptide. The hazard ratio was 1.69 (95% confidence interval, 1.17–2.45). The levels of circulating IGFBP-3 were positively associated with changes in serum C-peptide levels and showed a strong linear trend in the covariance analysis. Serum C-peptide level was associated with increased risk of breast cancer death. Our results suggest that the increased risk of breast cancer death can be via a pathway that serum C-peptide level positive associated with the change in serum IGFBP-3 level.
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Affiliation(s)
- PinYu Cui
- Department of Public Health, School of Medicine, Zhejiang University, Hangzhou, China
| | - Yuan Chen
- Department of Public Health, School of Medicine, Zhejiang University, Hangzhou, China
| | - Nuremaguli Waili
- Department of Public Health, School of Medicine, Zhejiang University, Hangzhou, China
| | - YaXing Li
- Department of Public Health, School of Medicine, Zhejiang University, Hangzhou, China
| | - CuiLing Ma
- Department of Public Health, School of Medicine, Zhejiang University, Hangzhou, China
| | - Ying Li
- Department of Public Health, School of Medicine, Zhejiang University, Hangzhou, China
- * E-mail:
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9
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Poteryaeva ON, Usynin IF. [Molecular mechanisms of action and physiological effects of the proinsulin C-peptide (a systematic review)]. BIOMEDIT︠S︡INSKAI︠A︡ KHIMII︠A︡ 2020; 66:196-207. [PMID: 32588825 DOI: 10.18097/pbmc20206603196] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The C-peptide is a fragment of proinsulin, the cleavage of which forms active insulin. In recent years, new information has appeared on the physiological effects of the C-peptide, indicating its positive effect on many organs and tissues, including the kidneys, nervous system, heart, vascular endothelium and blood microcirculation. Studies on experimental models of diabetes mellitus in animals, as well as clinical trials in patients with diabetes, have shown that the C-peptide has an important regulatory effect on the early stages of functional and structural disorders caused by this disease. The C-peptide exhibits its effects through binding to a specific receptor on the cell membrane and activation of downstream signaling pathways. Intracellular signaling involves G-proteins and Ca2+-dependent pathways, resulting in activation and increased expression of endothelial nitric oxide synthase, Na+/K+-ATPase and important transcription factors involved in apoptosis, anti-inflammatory and other intracellular defense mechanisms. This review gives an idea of the C-peptide as a bioactive endogenous peptide that has its own biological activity and therapeutic potential.
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Affiliation(s)
- O N Poteryaeva
- Institute of Biochemistry, Federal Research Center of Fundamental and Translation Medicine, Novosibirsk, Russia
| | - I F Usynin
- Institute of Biochemistry, Federal Research Center of Fundamental and Translation Medicine, Novosibirsk, Russia
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10
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Souto SB, Campos JR, Fangueiro JF, Silva AM, Cicero N, Lucarini M, Durazzo A, Santini A, Souto EB. Multiple Cell Signalling Pathways of Human Proinsulin C-Peptide in Vasculopathy Protection. Int J Mol Sci 2020; 21:E645. [PMID: 31963760 PMCID: PMC7013900 DOI: 10.3390/ijms21020645] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 01/15/2020] [Accepted: 01/16/2020] [Indexed: 12/19/2022] Open
Abstract
A major hallmark of diabetes is a constant high blood glucose level (hyperglycaemia), resulting in endothelial dysfunction. Transient or prolonged hyperglycemia can cause diabetic vasculopathy, a secondary systemic damage. C-Peptide is a product of cleavage of proinsulin by a serine protease that occurs within the pancreatic β-cells, being secreted in similar amounts as insulin. The biological activity of human C-peptide is instrumental in the prevention of diabetic neuropathy, nephropathy and other vascular complications. The main feature of type 1 diabetes mellitus is the lack of insulin and of C-peptide, but the progressive β-cell loss is also observed in later stage of type 2 diabetes mellitus. C-peptide has multifaceted effects in animals and diabetic patients due to the activation of multiple cell signalling pathways, highlighting p38 mitogen-activated protein kinase and extracellular signal-regulated kinase ½, Akt, as well as endothelial nitric oxide production. Recent works highlight the role of C-peptide in the prevention and amelioration of diabetes and also in organ-specific complications. Benefits of C-peptide in microangiopathy and vasculopathy have been shown through conservation of vascular function, and also in the prevention of endothelial cell death, microvascular permeability, neointima formation, and in vascular inflammation. Improvement of microvascular blood flow by replacing a physiological amount of C-peptide, in several tissues of diabetic animals and humans, mainly in nerve tissue, myocardium, skeletal muscle, and kidney has been described. A review of the multiple cell signalling pathways of human proinsulin C-peptide in vasculopathy protection is proposed, where the approaches to move beyond the state of the art in the development of innovative and effective therapeutic options of diabetic neuropathy and nephropathy are discussed.
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Affiliation(s)
- Selma B. Souto
- Department of Endocrinology, Hospital de São João, Alameda Prof. Hernâni Monteiro, 4200-319 Porto, Portugal;
| | - Joana R. Campos
- Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Coimbra (FFUC), Pólo das Ciências da Saúde, 3000-548 Coimbra, Portugal; (J.R.C.); (J.F.F.)
| | - Joana F. Fangueiro
- Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Coimbra (FFUC), Pólo das Ciências da Saúde, 3000-548 Coimbra, Portugal; (J.R.C.); (J.F.F.)
| | - Amélia M. Silva
- Department of Biology and Environment, University of Trás-os-Montes e Alto Douro, UTAD, Quinta de Prados, P-5001-801 Vila Real, Portugal;
- Centre for Research and Technology of Agro-Environmental and Biological Sciences, CITAB, UTAD, Quinta de Prados, P-5001-801 Vila Real, Portugal
| | - Nicola Cicero
- Dipartimento di Scienze biomediche, odontoiatriche e delle immagini morfologiche e funzionali, Università degli Studi di Messina, Polo Universitario Annunziata, 98168 Messina, Italy;
| | - Massimo Lucarini
- CREA—Research Centre for Food and Nutrition, Via Ardeatina 546, 00178 Rome, Italy; (M.L.); (A.D.)
| | - Alessandra Durazzo
- CREA—Research Centre for Food and Nutrition, Via Ardeatina 546, 00178 Rome, Italy; (M.L.); (A.D.)
| | - Antonello Santini
- Department of Pharmacy, University of Napoli Federico II, Via D. Montesano 49, 80131 Napoli, Italy
| | - Eliana B. Souto
- Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Coimbra (FFUC), Pólo das Ciências da Saúde, 3000-548 Coimbra, Portugal; (J.R.C.); (J.F.F.)
- CEB—Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
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11
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The effect of C-peptide on diabetic nephropathy: A review of molecular mechanisms. Life Sci 2019; 237:116950. [PMID: 31605709 DOI: 10.1016/j.lfs.2019.116950] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 10/07/2019] [Accepted: 10/08/2019] [Indexed: 02/07/2023]
Abstract
C-peptide is a small peptide connecting two chains of proinsulin molecule and is dissociated before the release of insulin. It is secreted in an equimolar amount to insulin from the pancreatic beta-cells into the circulation. Recent evidence demonstrates that it has other physiologic activities beyond its structural function. C-peptide modulates intracellular signaling pathways in various pathophysiologic states and, could potentially be a new therapeutic target for different disorders including diabetic complications. There is growing evidence that c-peptide has modulatory effects on the molecular mechanisms involved in the development of diabetic nephropathy. Although we have little direct evidence, pharmacological properties of c-peptide suggest that it can provide potent renoprotective effects especially, in a c-peptide deficient milieu as in type 1 diabetes mellitus. In this review, we describe possible molecular mechanisms by which c-peptide may improve renal efficiency in a diabetic milieu.
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12
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Essid SM, Bevington A, Brunskill NJ. Proinsulin C-Peptide Enhances Cell Survival and Protects against Simvastatin-Induced Myotoxicity in L6 Rat Myoblasts. Int J Mol Sci 2019; 20:ijms20071654. [PMID: 30987105 PMCID: PMC6479794 DOI: 10.3390/ijms20071654] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 03/22/2019] [Accepted: 03/25/2019] [Indexed: 12/12/2022] Open
Abstract
The repair capacity of progenitor skeletal muscle satellite cells (SC) in Type 1 diabetes mellitus (T1DM) is decreased. This is associated with the loss of skeletal muscle function. In T1DM, the deficiency of C-peptide along with insulin is associated with an impairment of skeletal muscle functions such as growth, and repair, and is thought to be an important contributor to increased morbidity and mortality. Recently, cholesterol-lowering drugs (statins) have also been reported to increase the risk of skeletal muscle dysfunction. We hypothesised that C-peptide activates key signaling pathways in myoblasts, thus promoting cell survival and protecting against simvastatin-induced myotoxicity. This was tested by investigating the effects of C-peptide on the L6 rat myoblast cell line under serum-starved conditions. Results: C-peptide at concentrations as low as 0.03 nM exerted stimulatory effects on intracellular signaling pathways—MAP kinase (ERK1/2) and Akt. When apoptosis was induced by simvastatin, 3 nM C-peptide potently suppressed the apoptotic effect through a pertussis toxin-sensitive pathway. Simvastatin strongly impaired Akt signaling and stimulated the reactive oxygen species (ROS) production; suggesting that Akt signaling and oxidative stress are important factors in statin-induced apoptosis in L6 myoblasts. The findings indicate that C-peptide exerts an important protective effect against death signaling in myoblasts. Therefore, in T1DM, the deficiency of C-peptide may contribute to myopathy by rendering myoblast-like progenitor cells (involved in muscle regeneration) more susceptible to the toxic effects of insults such as simvastatin.
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Affiliation(s)
- Sumia Mohamed Essid
- Department of Infection, Immunity and Inflammation, University of Leicester, Leicester LE1 7 RH, UK.
| | - Alan Bevington
- Department of Infection, Immunity and Inflammation, University of Leicester, Leicester LE1 7 RH, UK.
| | - Nigel J Brunskill
- Department of Infection, Immunity and Inflammation, University of Leicester, Leicester LE1 7 RH, UK.
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13
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Martin JH, Aitken RJ, Bromfield EG, Cafe SL, Sutherland JM, Frost ER, Nixon B, Lord T. Investigation into the presence and functional significance of proinsulin C-peptide in the female germline†. Biol Reprod 2019; 100:1275-1289. [DOI: 10.1093/biolre/ioz008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2018] [Revised: 12/10/2018] [Accepted: 01/28/2019] [Indexed: 12/26/2022] Open
Affiliation(s)
- Jacinta H Martin
- Priority Research Centre for Reproductive Science, Discipline of Biological Sciences, The Hunter Medical Research Institute, New Lambton Heights and the University of Newcastle, Callaghan, Newcastle, Australia
| | - R John Aitken
- Priority Research Centre for Reproductive Science, Discipline of Biological Sciences, The Hunter Medical Research Institute, New Lambton Heights and the University of Newcastle, Callaghan, Newcastle, Australia
| | - Elizabeth G Bromfield
- Priority Research Centre for Reproductive Science, Discipline of Biological Sciences, The Hunter Medical Research Institute, New Lambton Heights and the University of Newcastle, Callaghan, Newcastle, Australia
| | - Shenae L Cafe
- Priority Research Centre for Reproductive Science, Discipline of Biological Sciences, The Hunter Medical Research Institute, New Lambton Heights and the University of Newcastle, Callaghan, Newcastle, Australia
| | - Jessie M Sutherland
- Priority Research Centre for Reproductive Science, Discipline of Biological Sciences, The Hunter Medical Research Institute, New Lambton Heights and the University of Newcastle, Callaghan, Newcastle, Australia
| | - Emily R Frost
- Priority Research Centre for Reproductive Science, Discipline of Biological Sciences, The Hunter Medical Research Institute, New Lambton Heights and the University of Newcastle, Callaghan, Newcastle, Australia
| | - Brett Nixon
- Priority Research Centre for Reproductive Science, Discipline of Biological Sciences, The Hunter Medical Research Institute, New Lambton Heights and the University of Newcastle, Callaghan, Newcastle, Australia
| | - Tessa Lord
- Priority Research Centre for Reproductive Science, Discipline of Biological Sciences, The Hunter Medical Research Institute, New Lambton Heights and the University of Newcastle, Callaghan, Newcastle, Australia
- School of Molecular Biosciences, Centre for Reproductive Biology, College of Veterinary Medicine, Washington State University, Pullman, Washington, USA
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14
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Yu G, Wang W, Wang X, Xu M, Zhang L, Ding L, Guo R, Shi Y. Network pharmacology-based strategy to investigate pharmacological mechanisms of Zuojinwan for treatment of gastritis. BMC COMPLEMENTARY AND ALTERNATIVE MEDICINE 2018; 18:292. [PMID: 30382864 PMCID: PMC6211468 DOI: 10.1186/s12906-018-2356-9] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 10/18/2018] [Indexed: 12/17/2022]
Abstract
BACKGROUND Zuojinwan (ZJW), a classic herbal formula, has been extensively used to treat gastric symptoms in clinical practice in China for centuries. However, the pharmacological mechanisms of ZJW still remain vague to date. METHODS In the present work, a network pharmacology-based strategy was proposed to elucidate its underlying multi-component, multi-target, and multi-pathway mode of action against gastritis. First we collected putative targets of ZJW based on TCMSP and STITCH databases, and a network containing the interactions between the putative targets of ZJW and known therapeutic targets of gastritis was built. Then four topological parameters, "degree", "betweenness", "closeness", and "coreness" were calculated to identify the major targets in the network. Furthermore, the major hubs were imported to the Metacore database to perform a pathway enrichment analysis. RESULTS A total of 118 nodes including 59 putative targets of ZJW were picked out as major hubs in terms of their topological importance. The results of pathway enrichment analysis indicated that putative targets of ZJW mostly participated in various pathways associated with anti-inflammation response, growth and development promotion and G-protein-coupled receptor signaling. More importantly, five putative targets of ZJW (EGFR, IL-6, IL-1β, TNF-α and MCP-1) and two known therapeutic targets of gastritis (CCKBR and IL-12β) and a link target NF-κB were recognized as active factors involved in the main biological functions of treatment, implying the underlying mechanisms of ZJW acting on gastritis. CONCLUSION ZJW could alleviate gastritis through the molecular mechanisms predicted by network pharmacology, and this research demonstrates that the network pharmacology approach can be an effective tool to reveal the mechanisms of traditional Chinese medicine (TCM) from a holistic perspective.
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Affiliation(s)
- Guohua Yu
- School of Life Sciences, Beijing University of Chinese Medicine, No.11 East road, North 3rd Ring Road, Beijing, 100029 China
| | - Wubin Wang
- School of Life Sciences, Beijing University of Chinese Medicine, No.11 East road, North 3rd Ring Road, Beijing, 100029 China
| | - Xu Wang
- School of Life Sciences, Beijing University of Chinese Medicine, No.11 East road, North 3rd Ring Road, Beijing, 100029 China
| | - Meng Xu
- School of Life Sciences, Beijing University of Chinese Medicine, No.11 East road, North 3rd Ring Road, Beijing, 100029 China
| | - Lili Zhang
- School of Life Sciences, Beijing University of Chinese Medicine, No.11 East road, North 3rd Ring Road, Beijing, 100029 China
| | - Lei Ding
- School of Life Sciences, Beijing University of Chinese Medicine, No.11 East road, North 3rd Ring Road, Beijing, 100029 China
| | - Rui Guo
- School of Life Sciences, Beijing University of Chinese Medicine, No.11 East road, North 3rd Ring Road, Beijing, 100029 China
| | - Yuanyuan Shi
- School of Life Sciences, Beijing University of Chinese Medicine, No.11 East road, North 3rd Ring Road, Beijing, 100029 China
- Shenzhen Hospital, Beijing University of Chinese Medicine, No. 1 Dayun road, Sports New City Road, Shenzhen, 518172 China
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15
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Wang LY, Diao ZL, Zheng JF, Wu YR, Zhang QD, Liu WH. Apelin attenuates TGF-β1-induced epithelial to mesenchymal transition via activation of PKC-ε in human renal tubular epithelial cells. Peptides 2017; 96:44-52. [PMID: 28847490 DOI: 10.1016/j.peptides.2017.08.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2017] [Revised: 08/20/2017] [Accepted: 08/21/2017] [Indexed: 12/13/2022]
Abstract
Epithelial to mesenchymal transition (EMT), a process whereby fully differentiated epithelial cells transition to a mesenchymal phenotype, has been implicated in the pathogenesis of renal fibrosis. Apelin, a bioactive peptide, has recently been recognized to protect against renal profibrotic activity, but the underlying mechanism has not yet been elucidated. In this study, we investigated the regulation of EMT in the presence of apelin-13 in vitro. Expression of the mesenchymal marker alpha-smooth muscle actin (α-SMA) and the epithelial marker E-cadherin was examined by immunofluorescence and western blotting in transforming growth factor beta 1 (TGF-β1)-stimulated human proximal tubular epithelial cells. Expression of extracellular matrix, fibronectin and collagen-I was examined by quantitative real-time PCR and ELISA. F13A, an antagonist of the apelin receptor APJ, and small interfering RNA targeting protein kinase C epsilon (PKC-ε) were used to explore the relevant signaling pathways. Apelin attenuated TGF-β1-induced EMT, and inhibited the EMT-associated increase in α-SMA, loss of E-cadherin, and secretion of extracellular matrix. Moreover, apelin activated PKC-ε in tubular epithelial cells, which in turn decreased phospho-Smad2/3 levels and increased Smad-7 levels. APJ inhibition or PKC-ε deletion diminished apelin-induced modulation of Smad signaling and suppression of tubular EMT. Our findings identify a novel PKC-ε-dependent mechanism in which apelin suppresses TGF-β1-mediated activation of Smad signaling pathways and thereby inhibits tubular EMT. These results suggest that apelin may be a new agent that can suppress renal fibrosis and retard chronic kidney disease progression.
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Affiliation(s)
- Li-Yan Wang
- Department of Nephrology, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China
| | - Zong-Li Diao
- Department of Nephrology, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China
| | - Jun-Fang Zheng
- Department of Biochemistry and Molecular Biology, Capital Medical University, Beijing 100069, China
| | - Yi-Ru Wu
- Department of Nephrology, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China
| | - Qi-Dong Zhang
- Department of Nephrology, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China
| | - Wen-Hu Liu
- Department of Nephrology, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China.
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16
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Liang G, Song L, Chen Z, Qian Y, Xie J, Zhao L, Lin Q, Zhu G, Tan Y, Li X, Mohammadi M, Huang Z. Fibroblast growth factor 1 ameliorates diabetic nephropathy by an anti-inflammatory mechanism. Kidney Int 2017; 93:95-109. [PMID: 28750927 DOI: 10.1016/j.kint.2017.05.013] [Citation(s) in RCA: 107] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Revised: 04/30/2017] [Accepted: 05/04/2017] [Indexed: 11/15/2022]
Abstract
Inflammation plays a central role in the etiology of diabetic nephropathy, a global health issue. We observed a significant reduction in the renal expression of fibroblast growth factor 1, a known mitogen and insulin sensitizer, in patients with diabetic nephropathy and in mouse models implying that fibroblast growth factor 1 possesses beneficial anti-inflammatory and renoprotective activities in vivo. To test this possibility, we investigated the effects of chronic intraperitoneal administration of fibroblast growth factor 1 into both the streptozotocin-induced type 1 diabetes and db/db type 2 diabetes models. Indeed, recombinant fibroblast growth factor 1 significantly suppressed renal inflammation (i.e., cytokines, macrophage infiltration), glomerular and tubular damage, and renal dysfunction in both type 1 and type 2 diabetes mice. Fibroblast growth factor 1 was able to correct the elevated blood glucose levels in type 2 but not in type 1 diabetic mice, suggesting that the anti-inflammatory effect of fibroblast growth factor 1 was independent of its glucose-lowering activity. The mechanistic study demonstrated that fibroblast growth factor 1-mediated inhibition of the renal inflammation in vivo was accompanied by attenuation of the nuclear factor κB and c-Jun N-terminal kinase signaling pathways, further validated in vitro using cultured glomerular mesangial cells and podocytes. Thus, fibroblast growth factor 1 holds great promise for developing new treatments for diabetic nephropathy through countering inflammatory signaling cascades in injured renal tissue.
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Affiliation(s)
- Guang Liang
- School of Pharmaceutical Sciences and Center for Structural Biology, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Lintao Song
- School of Pharmaceutical Sciences and Center for Structural Biology, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Zilu Chen
- School of Pharmaceutical Sciences and Center for Structural Biology, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Yuanyuan Qian
- School of Pharmaceutical Sciences and Center for Structural Biology, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Junjun Xie
- School of Pharmaceutical Sciences and Center for Structural Biology, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Longwei Zhao
- School of Pharmaceutical Sciences and Center for Structural Biology, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Qian Lin
- Chinese-American Research Institute for Diabetic Complications, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Guanghui Zhu
- The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Yi Tan
- Chinese-American Research Institute for Diabetic Complications, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Xiaokun Li
- School of Pharmaceutical Sciences and Center for Structural Biology, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Moosa Mohammadi
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, New York, USA
| | - Zhifeng Huang
- School of Pharmaceutical Sciences and Center for Structural Biology, Wenzhou Medical University, Wenzhou, Zhejiang, China.
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17
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Russo C, Lazzaro V, Gazzaruso C, Maurotti S, Ferro Y, Pingitore P, Fumo F, Coppola A, Gallotti P, Zambianchi V, Fodaro M, Galliera E, Marazzi MG, Corsi Romanelli MM, Giannini S, Romeo S, Pujia A, Montalcini T. Proinsulin C-peptide modulates the expression of ERK1/2, type I collagen and RANKL in human osteoblast-like cells (Saos-2). Mol Cell Endocrinol 2017; 442:134-141. [PMID: 28007656 DOI: 10.1016/j.mce.2016.12.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 12/07/2016] [Accepted: 12/12/2016] [Indexed: 12/29/2022]
Abstract
A lower bone mass accompanied by a higher bone fragility with increased risk of fracture are observed in individuals with type 1 diabetes mellitus. Low C-peptide levels are associated with low lumbar mineral density in postmenopausal woman. In this work, we investigated the role of C-peptide on the osteoblast cell biology in vitro. We examined intracellular pathways and we found that C peptide activates ERK1/2 in human osteoblast-like cells (Saos-2). We also observed that proinsulin C-peptide prevents a reduction of type I collagen expression and decreases, in combination with insulin, receptor activator of nuclear factor-κB (RANKL) levels. In this work we show for the first time that Cpeptide activates a specific intracellular pathway in osteoblasts and it modulates the expression of protein involved in bone remodeling. Our results suggest that both C-peptide may have a role in bone metabolism. Further studies are needing to fully clarify its role.
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Affiliation(s)
- Cristina Russo
- Department of Medical and Surgical Sciences, University "Magna Graecia" of Catanzaro, Catanzaro, Italy
| | - Veronica Lazzaro
- Department of Health Sciences, University "Magna Graecia" of Catanzaro, Catanzaro, Italy
| | - Carmine Gazzaruso
- Internal and Emergency Medicine, and Ce.R.C.A. Clinical Institute "Beato Matteo", Vigevano, Italy
| | - Samantha Maurotti
- Department of Medical and Surgical Sciences, University "Magna Graecia" of Catanzaro, Catanzaro, Italy
| | - Yvelise Ferro
- Department of Medical and Surgical Sciences, University "Magna Graecia" of Catanzaro, Catanzaro, Italy
| | - Piero Pingitore
- Department of Molecular and Clinical Medicine, University of Gothenburg, Sweden
| | - Francesca Fumo
- Department of Medical and Surgical Sciences, University "Magna Graecia" of Catanzaro, Catanzaro, Italy
| | - Adriana Coppola
- Internal and Emergency Medicine, and Ce.R.C.A. Clinical Institute "Beato Matteo", Vigevano, Italy
| | - Pietro Gallotti
- Internal and Emergency Medicine, and Ce.R.C.A. Clinical Institute "Beato Matteo", Vigevano, Italy
| | - Valentina Zambianchi
- Internal and Emergency Medicine, and Ce.R.C.A. Clinical Institute "Beato Matteo", Vigevano, Italy
| | - Mariangela Fodaro
- Internal and Emergency Medicine, and Ce.R.C.A. Clinical Institute "Beato Matteo", Vigevano, Italy
| | - Emanuela Galliera
- Department of Biomedical, Surgical and Dental Science, University of Milan, Italy
| | | | | | - Sandro Giannini
- Department of Medical and Surgical Sciences, University of Padova, Italy
| | - Stefano Romeo
- Department of Medical and Surgical Sciences, University "Magna Graecia" of Catanzaro, Catanzaro, Italy; Department of Molecular and Clinical Medicine, University of Gothenburg, Sweden
| | - Arturo Pujia
- Department of Medical and Surgical Sciences, University "Magna Graecia" of Catanzaro, Catanzaro, Italy
| | - Tiziana Montalcini
- Department of Clinical and Experimental Medicine, University "Magna Graecia" of Catanzaro, Italy.
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18
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Abstract
Kidney disease is a serious development in diabetes mellitus and poses an increasing clinical problem. Despite increasing incidence and prevalence of diabetic kidney disease, there have been no new therapies for this condition in the last 20 years. Mounting evidence supports a biological role for C-peptide, and findings from multiple studies now suggest that C-peptide may beneficially affect the disturbed metabolic and pathophysiological pathways leading to the development of diabetic nephropathy. Studies of C-peptide in animal models and in humans with type 1 diabetes all suggest a renoprotective effect for this peptide. In diabetic rodents, C-peptide reduces glomerular hyperfiltration and albuminuria. Cohort studies of diabetic patients with combined islet and kidney transplants suggest that maintained C-peptide secretion is protective of renal graft function. Further, in short-term studies of patients with type 1 diabetes, administration of C-peptide is also associated with a lowered hyperfiltration rate and reduced microalbuminuria. Thus, the available information suggests that type 1 diabetes should be regarded as a dual hormone deficiency disease and that clinical trials of C-peptide in diabetic nephropathy are both justified and urgently required.
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Affiliation(s)
- N J Brunskill
- Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, UK
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19
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Pirkmajer S, Chibalin AV. Na,K-ATPase regulation in skeletal muscle. Am J Physiol Endocrinol Metab 2016; 311:E1-E31. [PMID: 27166285 DOI: 10.1152/ajpendo.00539.2015] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Accepted: 05/02/2016] [Indexed: 12/17/2022]
Abstract
Skeletal muscle contains one of the largest and the most dynamic pools of Na,K-ATPase (NKA) in the body. Under resting conditions, NKA in skeletal muscle operates at only a fraction of maximal pumping capacity, but it can be markedly activated when demands for ion transport increase, such as during exercise or following food intake. Given the size, capacity, and dynamic range of the NKA pool in skeletal muscle, its tight regulation is essential to maintain whole body homeostasis as well as muscle function. To reconcile functional needs of systemic homeostasis with those of skeletal muscle, NKA is regulated in a coordinated manner by extrinsic stimuli, such as hormones and nerve-derived factors, as well as by local stimuli arising in skeletal muscle fibers, such as contractions and muscle energy status. These stimuli regulate NKA acutely by controlling its enzymatic activity and/or its distribution between the plasma membrane and the intracellular storage compartment. They also regulate NKA chronically by controlling NKA gene expression, thus determining total NKA content in skeletal muscle and its maximal pumping capacity. This review focuses on molecular mechanisms that underlie regulation of NKA in skeletal muscle by major extrinsic and local stimuli. Special emphasis is given to stimuli and mechanisms linking regulation of NKA and energy metabolism in skeletal muscle, such as insulin and the energy-sensing AMP-activated protein kinase. Finally, the recently uncovered roles for glutathionylation, nitric oxide, and extracellular K(+) in the regulation of NKA in skeletal muscle are highlighted.
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Affiliation(s)
- Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia; and
| | - Alexander V Chibalin
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
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20
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Wahren J, Foyt H, Daniels M, Arezzo JC. Long-Acting C-Peptide and Neuropathy in Type 1 Diabetes: A 12-Month Clinical Trial. Diabetes Care 2016; 39:596-602. [PMID: 26884473 DOI: 10.2337/dc15-2068] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 01/04/2016] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Lack of C-peptide in type 1 diabetes may be an important contributing factor in the development of microvascular complications. Replacement of native C-peptide has been shown to exert a beneficial influence on peripheral nerve function in type 1 diabetes. The aim of this study was to evaluate the efficacy and safety of a long-acting C-peptide in subjects with type 1 diabetes and mild to moderate peripheral neuropathy. RESEARCH DESIGN AND METHODS A total of 250 patients with type 1 diabetes and peripheral neuropathy received long-acting (pegylated) C-peptide in weekly dosages of 0.8 mg (n = 71) or 2.4 mg (n = 73) or placebo (n = 106) for 52 weeks. Bilateral sural nerve conduction velocity (SNCV) and vibration perception threshold (VPT) on the great toe were measured on two occasions at baseline, at 26 weeks, and at 52 weeks. The modified Toronto Clinical Neuropathy Score (mTCNS) was used to grade the peripheral neuropathy. RESULTS Plasma C-peptide rose during the study to 1.8-2.2 nmol/L (low dose) and to 5.6-6.8 nmol/L (high dose). After 52 weeks, SNCV had increased by 1.0 ± 0.24 m/s (P < 0.001 within group) in patients receiving C-peptide (combined groups), but the corresponding value for the placebo group was 1.2 ± 0.29 m/s. Compared with basal, VPT had improved by 25% after 52 weeks of C-peptide therapy (Δ for combined C-peptide groups: -4.5 ± 1.0 μm, placebo group: -0.1 ± 0.9 μm; P < 0.001). mTCNS was unchanged during the study. CONCLUSIONS Once-weekly subcutaneous administration of long-acting C-peptide for 52 weeks did not improve SNCV, other electrophysiological variables, or mTCNS but resulted in marked improvement of VPT compared with placebo.
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Affiliation(s)
- John Wahren
- Cebix Inc., San Diego, CA Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
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21
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He T, Guan X, Wang S, Xiao T, Yang K, Xu X, Wang J, Zhao J. Resveratrol prevents high glucose-induced epithelial-mesenchymal transition in renal tubular epithelial cells by inhibiting NADPH oxidase/ROS/ERK pathway. Mol Cell Endocrinol 2015; 402:13-20. [PMID: 25540919 DOI: 10.1016/j.mce.2014.12.010] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2014] [Revised: 12/11/2014] [Accepted: 12/11/2014] [Indexed: 11/28/2022]
Abstract
Resveratrol (RSV) is reported to have renoprotective activity against diabetic nephropathy, while the mechanisms underlying its function have not been fully elucidated. In this study, we investigate the effect and related mechanism of RSV against high glucose-induced epithelial to mesenchymal transition (EMT) in human tubular epithelial cells (HK-2). A typical EMT is induced by high glucose in HK-2 cells, accompanied by increased levels of reactive oxygen species (ROS). RSV exhibits a strong ability to inhibit high glucose-induced EMT by decreasing intracellular ROS levels via down-regulation of NADPH oxidase subunits NOX1 and NOX4. The activation of extracellular signal-regulated kinase (ERK1/2) is found to be involved in high glucose-induced EMT in HK-2 cells. RSV, like NADPH oxidase inhibitor diphenyleneiodonium, can block ERK1/2 activation induced by high glucose. Our results demonstrate that RSV is a potent agent against high glucose-induced EMT in renal tubular cells via inhibition of NADPH oxidase/ROS/ERK1/2 pathway.
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Affiliation(s)
- Ting He
- Department of Nephrology, Institute of Nephrology of Chongqing and Kidney Center of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Xu Guan
- Department of Nephrology, Institute of Nephrology of Chongqing and Kidney Center of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Song Wang
- State Key Laboratory of Trauma, Burns and Combined Injury, Institute of Combined Injury of PLA, Third Military Medical University, Chongqing 400038, China
| | - Tangli Xiao
- Department of Nephrology, Institute of Nephrology of Chongqing and Kidney Center of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Ke Yang
- Department of Nephrology, Institute of Nephrology of Chongqing and Kidney Center of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Xinli Xu
- Department of Nephrology, Institute of Nephrology of Chongqing and Kidney Center of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Junping Wang
- State Key Laboratory of Trauma, Burns and Combined Injury, Institute of Combined Injury of PLA, Third Military Medical University, Chongqing 400038, China
| | - Jinghong Zhao
- Department of Nephrology, Institute of Nephrology of Chongqing and Kidney Center of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
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22
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Landreh M, Jörnvall H. C-peptide evolution: generation from few structural restrictions of bioactivities not necessarily functional. FEBS Lett 2015; 589:415-8. [PMID: 25595456 DOI: 10.1016/j.febslet.2015.01.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 12/30/2014] [Accepted: 01/07/2015] [Indexed: 11/28/2022]
Abstract
The proinsulin C-peptide has molecular, cellular and organismal activities but lacks disease-associated mutations or short-term loss-of-function effects. This dilemma between activity and function may be explained from its evolutionary setting with insulin as an ancestral partner. The charge, approximate length and flexibility of C-peptide are all that is required for the insulin interactions, while remaining aspects are free to evolve, where new bioactivities can emerge. They can initially be transient, weak, and non-functional, but may gradually be consolidated. In this manner, C-peptide may have acquired multiple bioactivities, explaining why some yet have limited functions but could represent early-stage hormonal-like activities.
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Affiliation(s)
- Michael Landreh
- Department of Medical Biochemistry and Biophysics (MBB), Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Hans Jörnvall
- Department of Medical Biochemistry and Biophysics (MBB), Karolinska Institutet, SE-171 77 Stockholm, Sweden.
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23
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Richards JP, Bowles EA, Gordon WR, Ellsworth ML, Stephenson AH, Sprague RS. Mechanisms of C-peptide-mediated rescue of low O2-induced ATP release from erythrocytes of humans with type 2 diabetes. Am J Physiol Regul Integr Comp Physiol 2014; 308:R411-8. [PMID: 25552662 DOI: 10.1152/ajpregu.00420.2014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The circulating erythrocyte, by virtue of the regulated release of ATP in response to reduced oxygen (O2) tension, plays a key role in maintaining appropriate perfusion distribution to meet tissue needs. Erythrocytes from individuals with Type 2 diabetes (DM2) fail to release ATP in response to this stimulus. However, the administration of C-peptide and insulin at a 1:1 ratio was shown to restore this important physiological response in humans with DM2. To begin to investigate the mechanisms by which C-peptide influences low O2-induced ATP release, erythrocytes from healthy humans and humans with DM2 were exposed to reduced O2 in a thin-film tonometer, and ATP release under these conditions was compared with release during normoxia. We determined that 1) low O2-induced ATP release from DM2 erythrocytes is rescued by C-peptide in the presence and absence of insulin, 2) the signaling pathway activated by C-peptide in human erythrocytes involves PKC, as well as soluble guanylyl cyclase (sGC) and 3) inhibitors of cGMP degradation rescue low O2-induced ATP release from DM2 erythrocytes. These results provide support for the hypothesis that both PKC and sGC are components of a signaling pathway activated by C-peptide in human erythrocytes. In addition, since both C-peptide and phosphodiesterase 5 inhibitors rescue low O2-induced ATP release from erythrocytes of humans with DM2, their administration to humans with DM2 could aid in the treatment and/or prevention of the vascular disease associated with this condition.
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Affiliation(s)
- Jennifer P Richards
- Department of Pharmacological and Physiological Science, Saint Louis University, St. Louis, Missouri
| | - Elizabeth A Bowles
- Department of Pharmacological and Physiological Science, Saint Louis University, St. Louis, Missouri
| | - Weston R Gordon
- Department of Pharmacological and Physiological Science, Saint Louis University, St. Louis, Missouri
| | - Mary L Ellsworth
- Department of Pharmacological and Physiological Science, Saint Louis University, St. Louis, Missouri
| | - Alan H Stephenson
- Department of Pharmacological and Physiological Science, Saint Louis University, St. Louis, Missouri
| | - Randy S Sprague
- Department of Pharmacological and Physiological Science, Saint Louis University, St. Louis, Missouri
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Yosten GLC, Maric-Bilkan C, Luppi P, Wahren J. Physiological effects and therapeutic potential of proinsulin C-peptide. Am J Physiol Endocrinol Metab 2014; 307:E955-68. [PMID: 25249503 PMCID: PMC4254984 DOI: 10.1152/ajpendo.00130.2014] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Connecting Peptide, or C-peptide, is a product of the insulin prohormone, and is released with and in amounts equimolar to those of insulin. While it was once thought that C-peptide was biologically inert and had little biological significance beyond its role in the proper folding of insulin, it is now known that C-peptide binds specifically to the cell membranes of a variety of tissues and initiates specific intracellular signaling cascades that are pertussis toxin sensitive. Although it is now clear that C-peptide is a biologically active molecule, controversy still remains as to the physiological significance of the peptide. Interestingly, C-peptide appears to reverse the deleterious effects of high glucose in some tissues, including the kidney, the peripheral nerves, and the vasculature. C-peptide is thus a potential therapeutic agent for the treatment of diabetes-associated long-term complications. This review addresses the possible physiologically relevant roles of C-peptide in both normal and disease states and discusses the effects of the peptide on sensory nerve, renal, and vascular function. Furthermore, we highlight the intracellular effects of the peptide and present novel strategies for the determination of the C-peptide receptor(s). Finally, a hypothesis is offered concerning the relationship between C-peptide and the development of microvascular complications of diabetes.
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Affiliation(s)
- Gina L C Yosten
- Department of Pharmacological and Physiological Science, Saint Louis University School of Medicine, St. Louis, Missouri;
| | - Christine Maric-Bilkan
- Division of Cardiovascular Sciences, Vascular Biology and Hypertension Branch, National Heart, Lung and Blood Institute, Bethesda, Maryland; Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi
| | - Patrizia Luppi
- Department of Cell Biology, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania
| | - John Wahren
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden; and Cebix Inc., Karolinska Institutet Science Park, Solna, Sweden
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25
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McKillop AM, Ng MT, Abdel-Wahab YHA, Flatt PR. Evidence for inhibitory autocrine effects of proinsulin C-peptide on pancreatic β-cell function and insulin secretion. Diabetes Obes Metab 2014; 16:937-46. [PMID: 24702738 DOI: 10.1111/dom.12300] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 02/28/2014] [Accepted: 03/31/2014] [Indexed: 12/21/2022]
Abstract
AIMS Autocrine and paracrine regulatory mechanisms ensure integrated secretion of islet hormones that respond efficiently to changes in metabolic need. As proinsulin C-peptide exerts various biological effects and binds to cell membranes including insulin-secreting β cells, its physiological role in insulin release was examined. METHODS Insulin releasing activity of human and rat C-peptides were studied in the clonal pancreatic cell line, BRIN-BD11, with findings substantiated using isolated islets and in vivo studies employing SWISS TO mice. RESULTS Acute exposure of clonal β cells to human C-peptide resulted in concentration-dependent inhibitory effects on insulin secretion at 5.6 mM (p < 0.05-p < 0.001) and 16.7 mM (p < 0.01-p < 0.001) glucose. At physiologically relevant intra-islet concentrations (10(-9) -10(-6) M), C-peptide suppressed the insulin-secretory responses to a range of secretagogues acting at different points in the β cell stimulus-secretion coupling pathway including alanine (p < 0.05), Ca(2+) (p < 0.001), arginine (p < 0.05), tolbutamide (p < 0.001), glucagon-like peptide 1 (GLP-1) (p < 0.001), isobutylmethylxanthine (IBMX) (p < 0.01) and KCl (p < 0.05). Similar results were obtained using isolated mouse pancreatic islets. Human C-peptide (3 × 10(-7) M, p < 0.001), somatostatin-14 (3 × 10(-7) M, p < 0.01) and diazoxide (300 µM, p < 0.001) reduced both alanine and glucose-stimulated insulin release by 43, 25 and 48%, respectively. The effects of human C-peptide were reproduced using rat C-peptide I and II. C-peptide also inhibited in vivo glucose-stimulated insulin release and impaired glucose tolerance in mice. CONCLUSIONS C-peptide is a biologically active endogenous peptide hormone that exerts inhibitory autocrine effects on pancreatic β-cell function. Mechanisms involving the activation of K(+) channels and a distal effect downstream of increased cytoplasmic Ca(2+) appear to be implicated in the inhibition of insulin secretion.
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Affiliation(s)
- A M McKillop
- SAAD Centre for Pharmacy & Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine, UK
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26
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Lim YC, Bhatt MP, Kwon MH, Park D, Na S, Kim YM, Ha KS. Proinsulin C-peptide prevents impaired wound healing by activating angiogenesis in diabetes. J Invest Dermatol 2014; 135:269-278. [PMID: 25007043 DOI: 10.1038/jid.2014.285] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Revised: 06/05/2014] [Accepted: 06/13/2014] [Indexed: 12/28/2022]
Abstract
Diabetes mellitus disrupts wound repair and leads to the development of chronic wounds, likely due to impaired angiogenesis. We previously demonstrated that human proinsulin C-peptide can protect against vasculopathy in diabetes; however, its role in impaired wound healing in diabetes has not been studied. We investigated the potential roles of C-peptide in protecting against impaired wound healing by inducing angiogenesis using streptozotocin-induced diabetic mice and human umbilical vein endothelial cells. Diabetes delayed wound healing in mouse skin, and C-peptide supplement using osmotic pumps significantly increased the rate of skin wound closure in diabetic mice. Furthermore, C-peptide induced endothelial cell migration and tube formation in dose-dependent manners, with maximal effect at 0.5 nM. These effects were mediated through activation of extracellular signal-regulated kinase 1/2 and Akt, as well as nitric oxide formation. C-peptide-enhanced angiogenesis in vivo was demonstrated by immunohistochemistry and Matrigel plug assays. Our findings highlight an angiogenic role of C-peptide and its ability to protect against impaired wound healing, which may have significant implications in reparative and therapeutic angiogenesis in diabetes. Thus, C-peptide replacement is a promising therapy for impaired angiogenesis and delayed wound healing in diabetes.
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Affiliation(s)
- Young-Cheol Lim
- Department of Molecular and Cellular Biochemistry and Institute of Medical Science, Kangwon National University School of Medicine, Chuncheon, Kangwon-do, Korea
| | - Mahendra Prasad Bhatt
- Department of Molecular and Cellular Biochemistry and Institute of Medical Science, Kangwon National University School of Medicine, Chuncheon, Kangwon-do, Korea
| | - Mi-Hye Kwon
- Department of Molecular and Cellular Biochemistry and Institute of Medical Science, Kangwon National University School of Medicine, Chuncheon, Kangwon-do, Korea
| | - Donghyun Park
- Department of Molecular and Cellular Biochemistry and Institute of Medical Science, Kangwon National University School of Medicine, Chuncheon, Kangwon-do, Korea
| | - SungHun Na
- Department of Obstetrics and Gynecology, Kangwon National University School of Medicine, Chuncheon, Kangwon-do, Korea
| | - Young-Myeong Kim
- Department of Molecular and Cellular Biochemistry and Institute of Medical Science, Kangwon National University School of Medicine, Chuncheon, Kangwon-do, Korea
| | - Kwon-Soo Ha
- Department of Molecular and Cellular Biochemistry and Institute of Medical Science, Kangwon National University School of Medicine, Chuncheon, Kangwon-do, Korea.
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Vejandla H, Hollander JM, Kothur A, Brock RW. C-Peptide reduces mitochondrial superoxide generation by restoring complex I activity in high glucose-exposed renal microvascular endothelial cells. ISRN ENDOCRINOLOGY 2012; 2012:162802. [PMID: 22778984 PMCID: PMC3388427 DOI: 10.5402/2012/162802] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Accepted: 04/10/2012] [Indexed: 12/02/2022]
Abstract
Hyperglycemia-mediated microvascular damage has been proposed to originate from excessive generation of mitochondrial superoxide in endothelial cells and is the suggested mechanism by which the pathogenesis of diabetes-induced renal damage occurs. C-peptide has been shown to ameliorate diabetes-induced renal impairment. Yet, the mechanisms underlying this protective benefit remain unclear. The objective of this study was to determine whether C-peptide affords protection to renal microvascular endothelial cell mitochondria during hyperglycemia. Conditionally immortalized murine renal microvascular endothelial cells (MECs) were exposed to low (5.5 mM) or high glucose (25 mM) media with either C-peptide (6.6 nM) or its scrambled sequence control peptide for 24 or 48 hours. Respiratory control ratio, a measure of mitochondrial electrochemical coupling, was significantly higher in high glucose renal MECs treated with C-peptide than those of high glucose alone. C-peptide also restored high glucose-induced renal MEC mitochondrial membrane potential changes back to their basal low glucose state. Moreover, C-peptide prevented the excessive mitochondrial superoxide generation and concomitant reductions in mitochondrial complex I activity which are mediated by the exposure of the renal MECs to high glucose. Together, these data demonstrate that C-peptide protects against high glucose-induced generation of mitochondrial superoxide in renal MECs via restoration of basal mitochondrial function.
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Affiliation(s)
- Himani Vejandla
- Department of Physiology and Pharmacology, West Virginia University School of Medicine, P.O. Box 9105, Morgantown, WV 26506, USA
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Proinflammatory effects of C-Peptide in different tissues. Int J Inflam 2012; 2012:932725. [PMID: 22762010 PMCID: PMC3384941 DOI: 10.1155/2012/932725] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 03/23/2012] [Accepted: 04/27/2012] [Indexed: 12/12/2022] Open
Abstract
Atherosclerosis is well known as an inflammatory disease that can lead to clinical complications such as heart attack or stroke. C-peptide as a cleavage product of proinsulin is in the last few decades known as an active peptide with a number of different effects on microvascular and macrovascular complications in type 2 diabetic patients. Patients with insulin resistance and early type 2 diabetes show elevated levels of C-peptide in blood. Several last findings demonstrated deposition of C-peptide in the vessel wall in ApoE-deficient mice and induction of local inflammation. Besides that, C-peptide has proliferative effects on human mesangial cells. This review discusses recently published proinflammatory effects of C-peptide in different tissues.
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Affiliation(s)
- John Wahren
- Department of Molecular Medicine and Surgery, Karolinska Institutet,Stockholm, Sweden.
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30
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C-peptide: a new mediator of atherosclerosis in diabetes. Mediators Inflamm 2012; 2012:858692. [PMID: 22547909 PMCID: PMC3321614 DOI: 10.1155/2012/858692] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Revised: 01/11/2012] [Accepted: 01/11/2012] [Indexed: 12/31/2022] Open
Abstract
Diabetes type 2 and insulin resistance are the risk factors for cardiovascular disease. It is already known that atherosclerosis is an inflammatory disease, and a lot of different factors are involved in its onset. C-peptide is a cleavage product of proinsulin, an active substance with a number of effects within different complications of diabetes. In this paper we discuss the role of C-peptide and its effects in the development of atherosclerosis in type 2 diabetic patients.
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Peruchetti DB, Pinheiro AAS, Landgraf SS, Wengert M, Takiya CM, Guggino WB, Caruso-Neves C. (Na+ + K+)-ATPase is a target for phosphoinositide 3-kinase/protein kinase B and protein kinase C pathways triggered by albumin. J Biol Chem 2011; 286:45041-7. [PMID: 22057272 PMCID: PMC3247955 DOI: 10.1074/jbc.m111.260737] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Revised: 10/25/2011] [Indexed: 12/14/2022] Open
Abstract
In recent decades, evidence has confirmed the crucial role of albumin in the progression of renal disease. However, the possible role of signaling pathways triggered by physiologic concentrations of albumin in the modulation of proximal tubule (PT) sodium reabsorption has not been considered. In the present work, we have shown that a physiologic concentration of albumin increases the expression of the α1 subunit of (Na(+) + K(+))-ATPase in LLC-PK1 cells leading to an increase in enzyme activity. This process involves the sequential activation of PI3K/protein kinase B and protein kinase C pathways promoting inhibition of protein kinase A. This integrative network is inhibited when albumin concentration is increased, similar to renal disease, leading to a decrease in the α1 subunit of (Na(+) + K(+))-ATPase expression. Together, the results indicate that variation in albumin concentration in PT cells has an important effect on PT sodium reabsorption and, consequently, on renal sodium excretion.
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Affiliation(s)
- Diogo B. Peruchetti
- From the Instituto de Biofísica Carlos Chagas Filho/Universidade Federal Rio de Janeiro, Centro de Ciências da Saúde, Bloco G, 21949-900 Rio de Janeiro, Brazil and
| | - Ana Acacia S. Pinheiro
- From the Instituto de Biofísica Carlos Chagas Filho/Universidade Federal Rio de Janeiro, Centro de Ciências da Saúde, Bloco G, 21949-900 Rio de Janeiro, Brazil and
| | - Sharon S. Landgraf
- From the Instituto de Biofísica Carlos Chagas Filho/Universidade Federal Rio de Janeiro, Centro de Ciências da Saúde, Bloco G, 21949-900 Rio de Janeiro, Brazil and
| | - Mira Wengert
- From the Instituto de Biofísica Carlos Chagas Filho/Universidade Federal Rio de Janeiro, Centro de Ciências da Saúde, Bloco G, 21949-900 Rio de Janeiro, Brazil and
| | - Christina M. Takiya
- From the Instituto de Biofísica Carlos Chagas Filho/Universidade Federal Rio de Janeiro, Centro de Ciências da Saúde, Bloco G, 21949-900 Rio de Janeiro, Brazil and
| | - William B. Guggino
- the Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Celso Caruso-Neves
- From the Instituto de Biofísica Carlos Chagas Filho/Universidade Federal Rio de Janeiro, Centro de Ciências da Saúde, Bloco G, 21949-900 Rio de Janeiro, Brazil and
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Galuska D, Pirkmajer S, Barrès R, Ekberg K, Wahren J, Chibalin AV. C-peptide increases Na,K-ATPase expression via PKC- and MAP kinase-dependent activation of transcription factor ZEB in human renal tubular cells. PLoS One 2011; 6:e28294. [PMID: 22162761 PMCID: PMC3230608 DOI: 10.1371/journal.pone.0028294] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Accepted: 11/04/2011] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Replacement of proinsulin C-peptide in type 1 diabetes ameliorates nerve and kidney dysfunction, conditions which are associated with a decrease in Na,K-ATPase activity. We determined the molecular mechanism by which long term exposure to C-peptide stimulates Na,K-ATPase expression and activity in primary human renal tubular cells (HRTC) in control and hyperglycemic conditions. METHODOLOGY/PRINCIPAL FINDINGS HRTC were cultured from the outer cortex obtained from patients undergoing elective nephrectomy. Ouabain-sensitive rubidium ((86)Rb(+)) uptake and Na,K-ATPase activity were determined. Abundance of Na,K-ATPase was determined by Western blotting in intact cells or isolated basolateral membranes (BLM). DNA binding activity was determined by electrical mobility shift assay (EMSA). Culturing of HRTCs for 5 days with 1 nM, but not 10 nM of human C-peptide leads to increase in Na,K-ATPase α(1)-subunit protein expression, accompanied with increase in (86)Rb(+) uptake, both in normal- and hyperglycemic conditions. Na,K-ATPase α(1)-subunit expression and Na,K-ATPase activity were reduced in BLM isolated from cells cultured in presence of high glucose. Exposure to1 nM, but not 10 nM of C-peptide increased PKCε phosphorylation as well as phosphorylation and abundance of nuclear ERK1/2 regardless of glucose concentration. Exposure to 1 nM of C-peptide increased DNA binding activity of transcription factor ZEB (AREB6), concomitant with Na,K-ATPase α(1)-subunit mRNA expression. Effects of 1 nM C-peptide on Na,K-ATPase α(1)-subunit expression and/or ZEB DNA binding activity in HRTC were abolished by incubation with PKC or MEK1/2 inhibitors and ZEB siRNA silencing. CONCLUSIONS/SIGNIFICANCE Despite activation of ERK1/2 and PKC by hyperglycemia, a distinct pool of PKCs and ERK1/2 is involved in regulation of Na,K-ATPase expression and activity by C-peptide. Most likely C-peptide stimulates sodium pump expression via activation of ZEB, a transcription factor that has not been previously implicated in C-peptide-mediated signaling. Importantly, only physiological concentrations of C-peptide elicit this effect.
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Affiliation(s)
- Dana Galuska
- Section of Integrative Physiology, Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Sergej Pirkmajer
- Section of Integrative Physiology, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Romain Barrès
- Section of Integrative Physiology, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Karin Ekberg
- Section of Integrative Physiology, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - John Wahren
- Section of Integrative Physiology, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Alexander V. Chibalin
- Section of Integrative Physiology, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
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Lindahl E, Nordquist L, Müller P, El Agha E, Friederich M, Dahlman-Wright K, Palm F, Jörnvall H. Early transcriptional regulation by C-peptide in freshly isolated rat proximal tubular cells. Diabetes Metab Res Rev 2011; 27:697-704. [PMID: 21618400 DOI: 10.1002/dmrr.1220] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Revised: 03/06/2011] [Accepted: 05/17/2011] [Indexed: 12/17/2022]
Abstract
BACKGROUND Clinical studies have shown that proinsulin C-peptide exerts renoprotective effects in type 1 diabetes, although the underlying mechanisms are poorly understood. As C-peptide has been shown to induce several intracellular events and to localize to nuclei, we aimed to determine whether gene transcription is affected in proximal tubular kidney cells, and if so, whether the genes with altered transcription include those related to protective mechanisms. METHODS The effect of C-peptide incubation (2 h) on gene expression was investigated in freshly isolated proximal tubular cells from streptozotocin-diabetic Sprague-Dawley rats using global gene expression profiling and real-time quantitative polymerase chain reaction. Protein expression was assayed using western blotting. Different bioinformatic strategies were employed. RESULTS Gene transcription profiling demonstrated differential transcription of 492 genes (p < 0.01) after 2 h of C-peptide exposure, with the majority of these genes repressed (83%). Real-time quantitative polymerase chain reaction validation supported a trend of several G protein-coupled receptors being activated, and certain transcription factors being repressed. Also, C-peptide repressed the transcription of genes associated with the pathways of circulatory and inflammatory diseases. CONCLUSION This study shows that C-peptide exerts early effects on gene transcription in proximal tubular cells. The findings also bring further knowledge to the renoprotective mechanisms of C-peptide in type 1 diabetes, and support a transcriptional activity for C-peptide. It is suggested that C-peptide may play a regulatory role in the gene expression of proximal tubular cells.
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Affiliation(s)
- Emma Lindahl
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
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Nordquist L, Palm F, Andresen BT. Renal and vascular benefits of C-peptide: Molecular mechanisms of C-peptide action. Biologics 2011; 2:441-52. [PMID: 19707375 PMCID: PMC2721399 DOI: 10.2147/btt.s3221] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
C-peptide has long been thought to be an inert byproduct of insulin production, but it has become apparent, and accepted, that C-peptide has important biological properties. C-peptide displays beneficial effects in many tissues affected by diabetic complications, such as increased peripheral blood flow and protection from renal damage. However, the mechanisms mediating these effects remain unclear. C-peptide interacts with cellular membranes at unidentified sites distinctive of the insulin family of receptors, and signals to multiple targets known to play a role in diabetes and diabetic complications, such as Na+/K+-ATPase and NOS. In general, the physiological and molecular effects of C-peptide resemble insulin, but C-peptide also possesses traits separate from those of insulin. These basic studies have been confirmed in human studies, suggesting that C-peptide may lend itself to clinical applications. However, the molecular and physiological properties of C-peptide are not completely elucidated, and large clinical studies have not begun. In order to further these goals, we critically summarize the current state of knowledge regarding C-peptide’s renal and vascular effects and the molecular signaling of C-peptide.
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Affiliation(s)
- Lina Nordquist
- Department of Medical Cell Biology, Division of Integrative Physiology, Uppsala University, Uppsala, Sweden
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Lind J, Lindahl E, Perálvarez-Marín A, Holmlund A, Jörnvall H, Mäler L. Structural features of proinsulin C-peptide oligomeric and amyloid states. FEBS J 2010; 277:3759-68. [PMID: 20738396 DOI: 10.1111/j.1742-4658.2010.07777.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The formation and structure of proinsulin C-peptide oligomers has been investigated by PAGE, NMR spectroscopy and dynamic light scattering. The results obtained show that C-peptide forms oligomers of different sizes, and that their formation and size distribution is altered by salt and divalent metal ions, which indicates that the aggregation process is mediated by electrostatic interactions. It is further demonstrated that the size distribution of the C-peptide oligomers, in agreement with previous studies, is altered by insulin, which supports a physiologically relevant interaction between these two peptides. A small fraction of oligomers has previously been suggested to be in equilibrium with a dominant fraction of soluble monomers, and this pattern also is observed in the present study. The addition of modest amounts of sodium dodecyl sulphate at low pH increases the relative amount of oligomers, and this effect was used to investigate the details of both oligomer formation and structure by a combination of biophysical techniques. The structural properties of the SDS-induced oligomers, as obtained by thioflavin T fluorescence, CD spectroscopy and IR spectroscopy, demonstrate that soluble aggregates are predominantly in β-sheet conformation, and that the oligomerization process shows characteristic features of amyloid formation. The formation of large, insoluble, β-sheet amyloid-like structures will alter the equilibrium between monomeric C-peptide and oligomers. This leads to the conclusion that the oligomerization of C-peptide may be relevant also at low concentrations.
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Affiliation(s)
- Jesper Lind
- Department of Biochemistry and Biophysics, Center for Biomembrane Research, The Arrhenius laboratory, Stockholm University, Stockholm, Sweden
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Lee SK, Lee JO, Kim JH, Jung JH, You GY, Park SH, Kim HS. C-peptide stimulates nitrites generation via the calcium-JAK2/STAT1 pathway in murine macrophage Raw264.7 cells. Life Sci 2010; 86:863-8. [PMID: 20388518 DOI: 10.1016/j.lfs.2010.03.022] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2009] [Revised: 03/19/2010] [Accepted: 03/22/2010] [Indexed: 01/25/2023]
Abstract
AIMS C-peptide is a product of pro-insulin cleavage. Numerous studies have demonstrated that C-peptide, although not influencing blood glucose control, may play a role in preventing and potentially reversing some of the chronic complications of type 1 diabetes. The aim of this paper was to present a novel function of C-peptide, focusing on its role in nitric oxide (NO) generation. MAIN METHODS Murine macrophage Raw264.7 cells and primary peritoneal macrophages were incubated under control conditions, or with C-peptide. Expression level of iNOS and phosphorylation status of JAK2/STAT1 were analyzed by Western blot. Fluorometric NO assay kit was used to assess the concentration of nitrite in culture medium. Intracellular calcium concentration was measured with calcium indicator dyes, such as Fura-2 and Fluo-3 AM. KEY FINDINGS C-peptide increased the level of nitrites in murine macrophage Raw264.7 cells. The nitrites production induced by lipopolysaccharide (LPS) was further enhanced by co-treatment of C-peptide. This up-regulation of nitrites generation also correlated with the induction of inducible nitric oxide synthase (iNOS), a prominent marker of macrophage activation. In addition, C-peptide increased the intracellular concentration of calcium levels. Moreover, C-peptide-induced nitrites generation and increase in calcium was observed in freshly isolated primary peritoneal macrophages. In addition, C-peptide specifically affected the Janus activated kinase (JAK)/signal transducer and activated transcription (STAT) pathway. Finally, C-peptide-mediated nitrites generation and JAK2/STAT1 phosphorylation were not detected in the presence of the intracellular calcium chelator, BAPTA-AM. SIGNIFICANCE These results suggest that C-peptide may elicit immune modulatory function via modulation of the calcium/JAK-STAT pathway.
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Affiliation(s)
- Soo Kyung Lee
- Department of Anatomy, Korea University College of Medicine, Seoul 136-701, Republic of Korea
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Abstract
Although long believed to be inert, C-peptide has now been shown to have definite biological effects both in vitro and in vivo in diabetic animals and in patients with type 1 diabetes. These effects point to a protective action of C-peptide against the development of diabetic microvascular complications. Underpinning these observations is undisputed evidence of C-peptide binding to a variety of cell types at physiologically relevant concentrations, and the downstream stimulation of multiple cell signaling pathways and gene transcription via the activation of numerous transcription factors. These pathways affect such fundamental cellular processes as re-absorptive and/or secretory phenotype, migration, growth, and survival. Whilst the receptor remains to be identified, experimental data points strongly to the existence of a specific G-protein-coupled receptor for C-peptide. Of the cell types studied so far, kidney tubular cells express the highest number of C-peptide binding sites. Accordingly, C-peptide exerts major effects on the function of these cells, and in the context of diabetic nephropathy appears to antagonise the pathophysiological effects of major disease mediators such as TGFbeta1 and TNFalpha. Therefore, based on its cellular activity profile C-peptide appears well positioned for development as a therapeutic tool to treat microvascular complications in type 1 diabetes.
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Affiliation(s)
- Claire E Hills
- Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, UK
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Forst T, Hach T, Kunt T, Weber MM, Pfützner A. Molecular effects of C-Peptide in microvascular blood flow regulation. Rev Diabet Stud 2009; 6:159-67. [PMID: 20039005 DOI: 10.1900/rds.2009.6.159] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
C-Peptide is produced in beta-cells in the pancreas, and secreted into the blood stream in equimolar amounts with insulin. For a long time, C-peptide was considered as an important component in the biosynthesis of insulin, but otherwise believed to possess minimal biological activity. In the recent years, numerous studies demonstrated that lacking C-peptide in type 1 diabetic patients might exert an important role in the development of microvascular complications such as nephropathy or neuropathy. There is increasing evidence that the biological effects of C-peptide are, at least in part, mediated through the modulation of endothelial function and microvascular blood flow. In several tissues, an increase in microvascular and nutritional blood flow could be observed during substitution of physiological amounts of C-peptide. Recent studies confirmed that C-peptide stimulates endothelial NO release by the activation of Ca2+ calmodulin-regulated endothelial NO synthase. A restoration of Na+/K+-ATPase activity during C-peptide supplementation could be observed in erythrocytes and renal tubular cells. The improvement of erythrocyte Na+/K+-ATPase is associated with an increase in erythrocyte deformability, and improved rheological properties. In this article, we consider the role of C-peptide in the context of endothelial function and microvascular blood flow as pathophysiologic components in the development of microvascular complications in patients with diabetes mellitus and loss of beta-cell function.
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Affiliation(s)
- Thomas Forst
- Institute for Clinical Research and Development, Parcusstr. 8, 55116 Mainz, Germany
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Nordquist L, Johansson M. Proinsulin C-peptide: friend or foe in the development of diabetes-associated complications? Vasc Health Risk Manag 2009; 4:1283-8. [PMID: 19337542 PMCID: PMC2663462 DOI: 10.2147/vhrm.s3955] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The proinsulin connecting peptide, C-peptide, is a cleavage product of insulin synthesis that is co-secreted with insulin by pancreatic β-cells following glucose stimulation. Recombinant insulin, used in the treatment of diabetes, lacks C-peptide and preclinical and clinical studies suggest that lack of C-peptide may exacerbate diabetes-associated complications. In accordance with this, several studies suggest that C-peptide has beneficial effects in a number of diabetes-associated complications. C-peptide has been shown to prevent diabetic neuropathy by improving endoneural blood flow, preventing neuronal apoptosis and by preventing axonal swelling. In the vascular system, C-peptide has been shown to prevent vascular dysfunction in diabetic rats, and to possess anti-proliferative effects on vascular smooth muscle cells, which may prevent atherosclerosis. However, C-peptide depositions have been found in arteriosclerotic lesions of patients with hyperinsulinemic diabetes and C-peptide has been shown to induce pro-inflammatory mediators, such as nuclear factor kappa B, inducible nitric oxide synthase, and cyclooxygenase-2, indicating that C-peptide treatment could be associated with side-effects that may accelerate the development of diabetes-associated complications. This review provides a brief summary of recent research in the field and discusses potential beneficial and detrimental effects of C-peptide supplementation.
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Affiliation(s)
- Lina Nordquist
- Department of Medical Cell Biology, Division of Integrative Physiology, Uppsala University, Uppsala, Sweden.
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Abstract
In recent years, accumulating evidence indicates a biological function for proinsulin C-peptide. These results challenge the traditional view that C-peptide is essentially inert and only useful as a surrogate marker of insulin release. Accordingly, it is now clear that C-peptide binds with high affinity to cell membranes, probably to a pertussis-toxin-sensitive G-protein-coupled receptor. Subsequently, multiple signalling pathways are potently and dose-dependently activated in multiple cell types by C-peptide with the resulting activation of gene transcription and altered cell phenotype. In diabetic animals and Type 1 diabetic patients, short-term studies indicate that C-peptide also enhances glucose disposal and metabolic control. Furthermore, results derived from animal models and clinical studies in Type 1 diabetic patients suggest a salutary effect of C-peptide in the prevention and amelioration of diabetic nephropathy and neuropathy. Therefore a picture of Type 1 diabetes as a dual-hormone-deficiency disease is developing, suggesting that the replacement of C-peptide alongside insulin should be considered in its management.
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C-peptide and its C-terminal fragments improve erythrocyte deformability in type 1 diabetes patients. EXPERIMENTAL DIABETES RESEARCH 2008; 2008:730594. [PMID: 18483566 PMCID: PMC2375968 DOI: 10.1155/2008/730594] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2007] [Accepted: 02/27/2008] [Indexed: 12/13/2022]
Abstract
Aims/hypothesis. Data now indicate that proinsulin C-peptide exerts important physiological effects and shows the characteristics of an endogenous peptide hormone. This study aimed to investigate the influence of C-peptide and fragments thereof on erythrocyte deformability and to elucidate the relevant signal transduction pathway.
Methods. Blood samples from 23 patients with type 1 diabetes and 15 matched healthy controls were incubated with 6.6 nM of either human C-peptide, C-terminal hexapeptide, C-terminal pentapeptide, a middle fragment comprising residues 11–19 of C-peptide, or randomly scrambled C-peptide. Furthermore, red blood cells from 7 patients were incubated with C-peptide, penta- and hexapeptides with/without addition of ouabain, EDTA, or pertussis toxin. Erythrocyte deformability was measured using a laser diffractoscope in the shear stress range 0.3–60 Pa. Results. Erythrocyte deformability was impaired by 18–25% in type 1 diabetic patients compared to matched controls in the physiological shear stress range 0.6–12 Pa (P < .01–.001). C-peptide, penta- and hexapeptide all significantly improved the impaired erythrocyte deformability of type 1 diabetic patients, while the middle fragment and scrambled C-peptide had no detectable effect. Treatment of erythrocytes with ouabain or EDTA completely abolished the C-peptide, penta- and hexapeptide effects. Pertussis toxin in itself significantly increased erythrocyte deformability. Conclusion/interpretation. C-peptide and its C-terminal fragments are equally effective in improving erythrocyte deformability in type 1 diabetes. The C-terminal residues of C-peptide are causally involved in this effect. The signal transduction pathway is Ca2+-dependent and involves activation of red blood cell Na+, K+-ATPase.
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Intracellular signalling by C-peptide. EXPERIMENTAL DIABETES RESEARCH 2008; 2008:635158. [PMID: 18382618 PMCID: PMC2276616 DOI: 10.1155/2008/635158] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Accepted: 02/06/2008] [Indexed: 12/11/2022]
Abstract
C-peptide, a cleavage product of the proinsulin molecule, has long been regarded as biologically inert, serving merely as a surrogate marker for insulin release. Recent findings demonstrate both a physiological and protective role of C-peptide when administered to individuals with type I diabetes. Data indicate that C-peptide appears to bind in nanomolar concentrations to a cell surface receptor which is most likely to be G-protein coupled. Binding of C-peptide initiates multiple cellular effects, evoking a rise in intracellular calcium, increased PI-3-kinase activity, stimulation of the Na(+)/K(+) ATPase, increased eNOS transcription, and activation of the MAPK signalling pathway. These cell signalling effects have been studied in multiple cell types from multiple tissues. Overall these observations raise the possibility that C-peptide may serve as a potential therapeutic agent for the treatment or prevention of long-term complications associated with diabetes.
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Sima AAF, Zhang W, Li ZG, Kamiya H. The effects of C-peptide on type 1 diabetic polyneuropathies and encephalopathy in the BB/Wor-rat. EXPERIMENTAL DIABETES RESEARCH 2008; 2008:230458. [PMID: 18437223 PMCID: PMC2323445 DOI: 10.1155/2008/230458] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2007] [Accepted: 01/07/2008] [Indexed: 12/29/2022]
Abstract
Diabetic polyneuropathy (DPN) occurs more frequently in type 1 diabetes resulting in a more severe DPN. The differences in DPN between the two types of diabetes are due to differences in the availability of insulin and C-peptide. Insulin and C-peptide provide gene regulatory effects on neurotrophic factors with effects on axonal cytoskeletal proteins and nerve fiber integrity. A significant abnormality in type 1 DPN is nodal degeneration. In the type 1 BB/Wor-rat, C-peptide replacement corrects metabolic abnormalities ameliorating the acute nerve conduction defect. It corrects abnormalities of neurotrophic factors and the expression of neuroskeletal proteins with improvements of axonal size and function. C-peptide corrects the expression of nodal adhesive molecules with prevention and repair of the functionally significant nodal degeneration. Cognitive dysfunction is a recognized complication of type 1 diabetes, and is associated with impaired neurotrophic support and apoptotic neuronal loss. C-peptide prevents hippocampal apoptosis and cognitive deficits. It is therefore clear that substitution of C-peptide in type 1 diabetes has a multitude of effects on DPN and cognitive dysfunction. Here the effects of C-peptide replenishment will be extensively described as they pertain to DPN and diabetic encephalopathy, underpinning its beneficial effects on neurological complications in type 1 diabetes.
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Affiliation(s)
- Anders A F Sima
- Department of Pathology, Wayne State University, Detroit, MI 48201, USA.
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Nordquist L, Lai EY, Sjöquist M, Patzak A, Persson AEG. Proinsulin C-peptide constricts glomerular afferent arterioles in diabetic mice. A potential renoprotective mechanism. Am J Physiol Regul Integr Comp Physiol 2007; 294:R836-41. [PMID: 18077505 DOI: 10.1152/ajpregu.00811.2007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
OBJECTIVE an increased glomerular filtration rate (GFR) has been postulated as a potential mechanism involved in the progression of diabetic nephropathy. Studies suggest that C-peptide exerts a renoprotective effect on diabetes. The peptide decreases hyperfiltration in patients with type 1 diabetes, as well as in diabetic animal models. In this study, we investigated whether C-peptide causes a change in arteriolar diameter. RESEARCH DESIGN AND METHODS C57-Bl mice were made diabetic by means of a single intravenous injection of alloxan 2 wk prior to the experiment. Age-matched normoglycemic mice served as controls. Afferent arterioles, intact with the glomeruli, were dissected and microperfused. The effect of luminal application of C-peptide, compared with scrambled C-peptide or vehicle, was investigated. The effect of the Rho-kinase inhibitor Y-27632 was also investigated. RESULTS C-peptide constricted afferent arterioles in diabetic mice by -27% compared with the control value. Normoglycemic arterioles administered C-peptide displayed a delayed and minute response (-4%). Scrambled C-peptide or vehicle administration, whether administered to hyperglycemic or normoglycemic mice, did not induce any effect. Addition of Y-27632 abolished the effect of C-peptide. CONCLUSION C-peptide induces constriction of afferent arterioles in diabetic mice. This can reduce enhanced GFR and may be one of the mechanisms in the renoprotective action of C-peptide in diabetes.
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Affiliation(s)
- Lina Nordquist
- Department of Medical Cell Biology, Division of Physiology, University of Uppsala, Uppsala, Sweden
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Regulation of the Na,K-ATPase: Special implications for cardiovascular complications of metabolic syndrome. PATHOPHYSIOLOGY 2007; 14:153-8. [DOI: 10.1016/j.pathophys.2007.09.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Wahren J, Ekberg K, Jörnvall H. C-peptide is a bioactive peptide. Diabetologia 2007; 50:503-9. [PMID: 17235526 DOI: 10.1007/s00125-006-0559-y] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2006] [Accepted: 10/24/2006] [Indexed: 11/24/2022]
Affiliation(s)
- J Wahren
- Department of Molecular Medicine and Surgery, Karolinska Hospital, 171 76, Stockholm, Sweden.
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Zhang W, Kamiya H, Ekberg K, Wahren J, Sima AAF. C-peptide improves neuropathy in type 1 diabetic BB/Wor-rats. Diabetes Metab Res Rev 2007; 23:63-70. [PMID: 16845685 DOI: 10.1002/dmrr.672] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
BACKGROUND The spontaneously diabetic BB/Wor-rat is a close model of human type 1 diabetes and develops diabetic polyneuropathy (DPN) similar to that seen in type 1 patients. Here we examine the therapeutic effects of C-peptide, delivered as continuous infusion or once daily subcutaneous injections on established DPN. METHODS Diabetic rats were treated from four to seven months duration of diabetes with full continuous replacement dose of rat C-peptide via (a) osmopumps (OS), (b) full replacement dose (HSC) or (c) one-third of full replacement dose (LSC) by once daily injections. RESULTS Diabetic rats treated with OS showed improvements in motor nerve conduction velocity (p < 0.001), sural nerve myelinated fibre number (p < 0.005), size (p < 0.05), axonal area (p < 0.001), regeneration (p < 0.001) and overall neuropathy score (p < 0.001). The progressive decline in sensory nerve conduction velocity was fully prevented. The frequencies of Wallerian degeneration were decreased (p < 0.005). HSC-treated rats showed prevention of further progression of DPN (p < 0.001), whereas LSC-treated rats showed a milder progression of DPN (p < 0.001) compared to untreated rats as assessed by neuropathy score. CONCLUSION We conclude that (1) C-peptide is effective in the treatment of established DPN, (2) its effect is dose-dependent and (3) replacement by continuous infusion is the most effective administration of C-peptide.
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Affiliation(s)
- Weixian Zhang
- Department of Pathology, Wayne State University, School of Medicine, Detroit, MI 48201, USA
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Ekberg K, Brismar T, Johansson BL, Lindström P, Juntti-Berggren L, Norrby A, Berne C, Arnqvist HJ, Bolinder J, Wahren J. C-Peptide replacement therapy and sensory nerve function in type 1 diabetic neuropathy. Diabetes Care 2007; 30:71-6. [PMID: 17192336 DOI: 10.2337/dc06-1274] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE C-peptide replacement in animals results in amelioration of diabetes-induced functional and structural abnormalities in peripheral nerves. The present study was undertaken to examine whether C-peptide administration to patients with type 1 diabetes and peripheral neuropathy improves sensory nerve function. RESEARCH DESIGN AND METHODS This was an exploratory, double-blinded, randomized, and placebo-controlled study with three study groups that was carried out at five centers in Sweden. C-peptide was given as a replacement dose (1.5 mg/day, divided into four subcutaneous doses) or a dose three times higher (4.5 mg/day) during 6 months. Neurological examination and neurophysiological measurements were performed before and after 6 months of treatment with C-peptide or placebo. RESULTS The age of the 139 patients who completed the protocol was 44.2 +/- 0.6 (mean +/- SE) years and their duration of diabetes was 30.6 +/- 0.8 years. Clinical neurological impairment (NIA) (score >7 points) of the lower extremities was present in 86% of the patients at baseline. Sensory nerve conduction velocity (SCV) was 2.6 +/- 0.08 SD below body height-corrected normal values at baseline and improved similarly within the two C-peptide groups (P < 0.007). The number of patients responding with a SCV peak potential improvement >1.0 m/s was greater in C-peptide-treated patients than in those receiving placebo (P < 0.03). In the least severely affected patients (SCV < 2.5 SD below normal at baseline, n = 70) SCV improved by 1.0 m/s (P < 0.014 vs. placebo). NIA score and vibration perception both improved within the C-peptide-treated groups (P < 0.011 and P < 0.002). A1C levels (7.6 +/- 0.1% at baseline) decreased slightly but similarly in C-peptide-and placebo-treated patients during the study. CONCLUSIONS C-peptide treatment for 6 months improves sensory nerve function in early-stage type 1 diabetic neuropathy.
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Affiliation(s)
- Karin Ekberg
- Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden.
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Mares-Guia TR, Maigret B, Martins NF, Maia ALT, Vilela L, Ramos CHI, Neto LJ, Juliano MA, dos Mares-Guia ML, Santoro MM. Molecular dynamics and circular dichroism studies of human and rat C-peptides. J Mol Graph Model 2006; 25:532-42. [PMID: 16750642 DOI: 10.1016/j.jmgm.2006.03.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2005] [Revised: 03/11/2006] [Accepted: 03/12/2006] [Indexed: 10/24/2022]
Abstract
Proinsulin C-peptide has been recently described as an endogenous peptide hormone, responsible for important physiological functions others than its role in proinsulin processing. Accumulating evidences that C-peptide exerts beneficial effects in the treatment of long term complications of patients with type 1 diabetes mellitus indicate that this molecule may be administered together with insulin in future therapies. Despite its clear pharmacological interest, the secondary and three-dimensional (3D) structures of human C-peptide are still points of controversy. In the present work we report molecular dynamics (MD) simulations of human, rat I and rat II C-peptides. A common experimental strategy applied to all peptides consisted of homology building followed by multinanosecond MD simulations in vacuum and water. Circular dichroism (CD) experiments of each peptide in the absence and presence of 2,2,2-trifluoroethanol (TFE) were performed to support validation of the theoretical models. A multiple sequence alignment of 23 known mammalian C-peptides was constructed to identify significant conserved sites that would be important for the maintenance of secondary and tertiary structures. The analysis of the molecular dynamics trajectories for the human, rat I and rat II molecules have shown quite different general behavior, being the human C-peptide more flexible than the two others. Human and rat C-peptides exhibit very stable turn-like structures at the middle and C-terminal regions, which have been described as potential active sites of C-peptides. Human C-peptide also presented a short alpha-helix throughout the MD, which was not found in the rat molecules. CD data is in very good agreement with the MD results and both methods were able to identify a greater structural stability and potential in rat C-peptides when compared to the human C-peptide. The simulation results are discussed and validated in the light of multiple sequence alignment, recent experimental data from the literature and our own CD experiments.
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Affiliation(s)
- Thiago Rennó Mares-Guia
- Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, 31270-901 Belo Horizonte, Brazil.
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Kamiya H, Zhang W, Ekberg K, Wahren J, Sima AAF. C-Peptide reverses nociceptive neuropathy in type 1 diabetes. Diabetes 2006; 55:3581-7. [PMID: 17130507 DOI: 10.2337/db06-0396] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We examined the therapeutic effects of C-peptide on established nociceptive neuropathy in type 1 diabetic BB/Wor rats. Nociceptive nerve function, unmyelinated sural nerve fiber and dorsal root ganglion (DRG) cell morphometry, nociceptive peptide content, and the expression of neurotrophic factors and their receptors were investigated. C-peptide was administered either as a continuous subcutaneous replacement dose via osmopumps or a replacement dose given once daily by subcutaneous injection. Diabetic rats were treated from 4 to 7 months of diabetes and were compared with control and untreated diabetic rats of 4- and 7-month duration. Osmopump delivery but not subcutaneous injection improved hyperalgesia and restored the diabetes-induced reduction of unmyelinated fiber number (P < 0.01) and mean axonal size (P < 0.05) in the sural nerve. High-affinity nerve growth factor (NGF) receptor (NGFR-TrkA) expression in DRGs was significantly reduced at 4 months (P < 0.01). Insulin receptor and IGF-I receptor (IGF-IR) expressions in DRGs and NGF content in sciatic nerve were significantly decreased in 7-month diabetic rats (P < 0.01, 0.05, and 0.005, respectively). Osmopump delivery prevented the decline of NGFR-TrkA, insulin receptor (P < 0.05), and IGF-IR (P < 0.005) expressions in DRGs and improved NGF content (P < 0.05) in sciatic nerve. However, subcutaneous injection had only marginal effects on morphometric and molecular changes in diabetic rats. We conclude that C-peptide exerts beneficial therapeutic effects on diabetic nociceptive neuropathy and that optimal effects require maintenance of physiological C-peptide concentrations for a major proportion of the day.
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Affiliation(s)
- Hideki Kamiya
- Department of Pathology, Scott Hall 9275, 540 E. Canfield Ave., Detroit, MI 48201, USA
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