1
|
Yang H, Bai J, Li L, Yang Y, Zhang Y, Lv H, Fu S. Association of C-peptide level with bone mineral density in type 2 diabetes mellitus. Osteoporos Int 2023:10.1007/s00198-023-06785-9. [PMID: 37204453 DOI: 10.1007/s00198-023-06785-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 05/01/2023] [Indexed: 05/20/2023]
Abstract
This study revealed that there was no significant linear relationship between fasting C-peptide (FCP) level and bone mineral density (BMD) or fracture risk in type 2 diabetes mellitus (T2DM) patients. However, in the FCP ≤ 1.14 ng/ml group, FCP is positively correlated with whole body (WB), lumbar spine (LS), and femoral neck (FN) BMD and negatively correlated with fracture risk. PURPOSE To explore the relationship between C-peptide and BMD and fracture risk in T2DM patients. METHODS 530 T2DM patients were enrolled and divided into three groups by FCP tertiles, and the clinical data were collected. BMD was measured by dual-energy X-ray absorptiometry (DXA). The 10-year probability of major osteoporotic fractures (MOFs) and hip fractures (HFs) was evaluated by adjusted fracture risk assessment tool (FRAX). RESULTS In the FCP ≤ 1.14 ng/ml group, FCP level was positively correlated with WB, LS, and FN BMD, while FCP was negatively correlated with fracture risk and osteoporotic fracture history. However, FCP was not correlated with BMD and fracture risk and osteoporotic fracture history in the 1.14 < FCP ≤ 1.73 ng/ml and FCP > 1.73 ng/ml groups. The study has shown that FCP was an independent factor influencing BMD and fracture risk in the FCP ≤ 1.14 ng/ml group. CONCLUSIONS There is no significant linear relationship between FCP level and BMD or fracture risk in T2DM patients. In the FCP ≤ 1.14 ng/ml group, FCP is positively correlated with WB, LS, and FN BMD and negatively correlated with fracture risk, and FCP is an independent influencing factor of BMD and fracture risk. The findings suggest that FCP may predict the risk of osteoporosis or fracture in some T2DM patients, which has a certain clinical value.
Collapse
Affiliation(s)
- Hong Yang
- The First School of Clinical Medicine, Lanzhou University, Lanzhou, Gansu, China
| | - Jia Bai
- The First School of Clinical Medicine, Lanzhou University, Lanzhou, Gansu, China
| | - Lingling Li
- The First School of Clinical Medicine, Lanzhou University, Lanzhou, Gansu, China
| | - Ying Yang
- The First School of Clinical Medicine, Lanzhou University, Lanzhou, Gansu, China
| | - Yangyang Zhang
- The First School of Clinical Medicine, Lanzhou University, Lanzhou, Gansu, China
| | - Haihong Lv
- Department of Endocrinology, The First Hospital of Lanzhou University, Lanzhou, Gansu, China.
| | - Songbo Fu
- Department of Endocrinology, The First Hospital of Lanzhou University, Lanzhou, Gansu, China
| |
Collapse
|
2
|
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.
Collapse
Affiliation(s)
- D Vejrazkova
- Department of Molecular Endocrinology, Institute of Endocrinology, Prague, Czech Republic.
| | | | | | | | | |
Collapse
|
3
|
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.
Collapse
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.
| |
Collapse
|
4
|
Biological activity versus physiological function of proinsulin C-peptide. Cell Mol Life Sci 2020; 78:1131-1138. [PMID: 32959070 PMCID: PMC7897624 DOI: 10.1007/s00018-020-03636-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 08/07/2020] [Accepted: 09/03/2020] [Indexed: 11/06/2022]
Abstract
Proinsulin C-peptide (C-peptide) has drawn much research attention. Even if the peptide has turned out not to be important in the treatment of diabetes, every phase of C-peptide research has changed our view on insulin and peptide hormone biology. The first phase revealed that peptide hormones can be subject to processing, and that their pro-forms may involve regulatory stages. The second phase revealed the possibility that one prohormone could harbor more than one activity, and that the additional activities should be taken into account in the development of hormone-based therapies. In the third phase, a combined view of the evolutionary patterns in hormone biology allowed an assessment of C-peptide´s role in physiology, and of how biological activities and physiological functions are shaped by evolutionary processes. In addition to this distinction, C-peptide research has produced further advances. For example, C-peptide fragments are successfully administered in immunotherapy of type I diabetes, and plasma C-peptide levels remain a standard for measurement of beta cell activity in patients. Even if the concept of C-peptide as a hormone is presently not supported, some of its bioactivities continue to influence our understanding of evolutionary changes of also other peptides.
Collapse
|
5
|
Kolar GR, Grote SM, Yosten GLC. Targeting orphan G protein-coupled receptors for the treatment of diabetes and its complications: C-peptide and GPR146. J Intern Med 2017; 281:25-40. [PMID: 27306986 PMCID: PMC6092955 DOI: 10.1111/joim.12528] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
G protein-coupled receptors (GPCRs) are the most abundant receptor family encoded by the human genome and are the targets of a high percentage of drugs currently in use or in clinical trials for the treatment of diseases such as diabetes and its associated complications. Thus, orphan GPCRs, for which the ligand is unknown, represent an important untapped source of therapeutic potential for the treatment of many diseases. We have identified the previously orphan GPCR, GPR146, as the putative receptor of proinsulin C-peptide, which may prove to be an effective treatment for diabetes-associated complications. For example, we have found a potential role of C-peptide and GPR146 in regulating the function of the retinal pigment epithelium, a monolayer of cells in the retina that serves as part of the blood-retinal barrier and is disrupted in diabetic macular oedema. However, C-peptide signalling in this cell type appears to depend at least in part on extracellular glucose concentration and its interaction with insulin. In this review, we discuss the therapeutic potential of orphan GPCRs with a special focus on C-peptide and GPR146, including past and current strategies used to 'deorphanize' this diverse family of receptors, past successes and the inherent difficulties of this process.
Collapse
Affiliation(s)
- G R Kolar
- Department of Pathology, St Louis University School of Medicine, St Louis, MO, USA
| | - S M Grote
- Department of Pharmacology and Physiology, St Louis University School of Medicine, St Louis, MO, USA
| | - G L C Yosten
- Department of Pharmacology and Physiology, St Louis University School of Medicine, St Louis, MO, USA
| |
Collapse
|
6
|
Garcia-Serrano S, Gutiérrez-Repiso C, Gonzalo M, Garcia-Arnes J, Valdes S, Soriguer F, Perez-Valero V, Alaminos-Castillo MA, Francisco Cobos-Bravo J, Moreno-Ruiz FJ, Rodriguez-Cañete A, Rodríguez-Pacheco F, Garcia-Escobar E, García-Fuentes E. C-peptide modifies leptin and visfatin secretion in human adipose tissue. Obesity (Silver Spring) 2015; 23:1607-15. [PMID: 26146822 DOI: 10.1002/oby.21137] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Revised: 02/24/2015] [Accepted: 03/29/2015] [Indexed: 12/17/2022]
Abstract
OBJECTIVE The effects of C-peptide on adipose tissue, an organ involved in the development of obesity and insulin resistance, are not yet well known. The aim of this study was to determine whether C-peptide could be involved in the regulation of the adipocytokine synthesis in human visceral adipose tissue. METHODS The association between C-peptide and different serum adipocytokines, with an intravenous glucose tolerance test (IVGTT), and in an in vitro study in subjects without obesity and in subjects with morbid obesity were analyzed. RESULTS In different multiple regression analysis models, C-peptide and C-peptide increase above basal levels during total IVGTT and between 0 and 10 min were associated positively with leptin and negatively with visfatin. Rhodamine-labeled C-peptide binds to human adipocytes, and this binding was blocked with excess of unlabeled C-peptide. Exposure of human visceral explants and adipocytes from subjects with morbid obesity to C-peptide at 1 and 10 nM induced a significant increase in leptin and a decrease in visfatin secretion. In subjects without obesity, these C-peptide effects were found mainly at 10 nM. These effects can be inhibited by phosphatidylinositol 3-kinase (PI3K) or protein kinase B (PKB) inhibitors. CONCLUSIONS C-peptide may be involved in the regulation of leptin and visfatin secretion, molecules intimately involved in energy homeostasis processes, through PI3K or PKB pathways.
Collapse
Affiliation(s)
- Sara Garcia-Serrano
- Unidad De Gestión Clínica De Endocrinología Y Nutrición, Instituto De Investigacion Biomédica De Málaga (IBIMA), Hospital Regional Universitario, Málaga, Spain
- CIBER De Diabetes Y Enfermedades Metabólicas (CIBERDEM), Málaga, Spain
| | - Carolina Gutiérrez-Repiso
- Unidad De Gestión Clínica De Endocrinología Y Nutrición, Instituto De Investigacion Biomédica De Málaga (IBIMA), Hospital Regional Universitario, Málaga, Spain
| | - Montserrat Gonzalo
- Unidad De Gestión Clínica De Endocrinología Y Nutrición, Instituto De Investigacion Biomédica De Málaga (IBIMA), Hospital Regional Universitario, Málaga, Spain
| | - Juan Garcia-Arnes
- Unidad De Gestión Clínica De Endocrinología Y Nutrición, Instituto De Investigacion Biomédica De Málaga (IBIMA), Hospital Regional Universitario, Málaga, Spain
| | - Sergio Valdes
- Unidad De Gestión Clínica De Endocrinología Y Nutrición, Instituto De Investigacion Biomédica De Málaga (IBIMA), Hospital Regional Universitario, Málaga, Spain
- CIBER De Diabetes Y Enfermedades Metabólicas (CIBERDEM), Málaga, Spain
| | - Federico Soriguer
- Unidad De Gestión Clínica De Endocrinología Y Nutrición, Instituto De Investigacion Biomédica De Málaga (IBIMA), Hospital Regional Universitario, Málaga, Spain
- CIBER De Diabetes Y Enfermedades Metabólicas (CIBERDEM), Málaga, Spain
- CIBER Fisiopatología De La Obesidad Y Nutrición (CIBEROBN), Málaga, Spain
| | - Vidal Perez-Valero
- Unidad De Gestión Clínica De Laboratorio, Instituto De Investigacion Biomédica De Málaga (IBIMA), Hospital Regional Universitario, Málaga, Spain
| | - Miguel A Alaminos-Castillo
- Unidad De Gestión Clínica De Laboratorio, Instituto De Investigacion Biomédica De Málaga (IBIMA), Hospital Regional Universitario, Málaga, Spain
| | - Juan Francisco Cobos-Bravo
- Unidad De Gestión Clínica De Cirugía General, Digestiva Y Trasplantes, Instituto De Investigacion Biomédica De Málaga (IBIMA), Hospital Regional Universitario, Málaga, Spain
| | - Francisco J Moreno-Ruiz
- Unidad De Gestión Clínica De Cirugía General, Digestiva Y Trasplantes, Instituto De Investigacion Biomédica De Málaga (IBIMA), Hospital Regional Universitario, Málaga, Spain
| | - Alberto Rodriguez-Cañete
- Unidad De Gestión Clínica De Cirugía General, Digestiva Y Trasplantes, Instituto De Investigacion Biomédica De Málaga (IBIMA), Hospital Regional Universitario, Málaga, Spain
| | - Francisca Rodríguez-Pacheco
- Unidad De Gestión Clínica De Endocrinología Y Nutrición, Instituto De Investigacion Biomédica De Málaga (IBIMA), Hospital Regional Universitario, Málaga, Spain
- CIBER De Diabetes Y Enfermedades Metabólicas (CIBERDEM), Málaga, Spain
| | - Eva Garcia-Escobar
- Unidad De Gestión Clínica De Endocrinología Y Nutrición, Instituto De Investigacion Biomédica De Málaga (IBIMA), Hospital Regional Universitario, Málaga, Spain
- CIBER De Diabetes Y Enfermedades Metabólicas (CIBERDEM), Málaga, Spain
| | - Eduardo García-Fuentes
- Unidad De Gestión Clínica De Endocrinología Y Nutrición, Instituto De Investigacion Biomédica De Málaga (IBIMA), Hospital Regional Universitario, Málaga, Spain
- CIBER Fisiopatología De La Obesidad Y Nutrición (CIBEROBN), Málaga, Spain
| |
Collapse
|
7
|
Yosten GLC, Kolar GR. The Physiology of Proinsulin C-Peptide: Unanswered Questions and a Proposed Model. Physiology (Bethesda) 2015; 30:327-32. [DOI: 10.1152/physiol.00008.2015] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
C-peptide is produced, processed, and secreted with insulin, and appears to exert separate but intimately related effects. In this review, we address the existence of the C-peptide receptor, the interaction between C-peptide and insulin, and the potential physiological significance of proinsulin C-peptide.
Collapse
Affiliation(s)
- Gina L. C. Yosten
- Department of Pharmacological and Physiological Science, St. Louis University School of Medicine, St. Louis, Missouri; and
| | - Grant R. Kolar
- Department of Pathology, St. Louis University School of Medicine, St. Louis, Missouri
| |
Collapse
|
8
|
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.
Collapse
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
| |
Collapse
|
9
|
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.
Collapse
Affiliation(s)
- A M McKillop
- SAAD Centre for Pharmacy & Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine, UK
| | | | | | | |
Collapse
|
10
|
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.
Collapse
|
11
|
Jameson DM, Ross JA, Albanesi JP. Fluorescence fluctuation spectroscopy: ushering in a new age of enlightenment for cellular dynamics. Biophys Rev 2009; 1:105-118. [PMID: 21547245 DOI: 10.1007/s12551-009-0013-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Originally developed for applications in physics and physical chemistry, fluorescence fluctuation spectroscopy is becoming widely used in cell biology. This review traces the development of the method and describes some of the more important applications. Specifically, the methods discussed include fluorescence correlation spectroscopy (FCS), scanning FCS, dual color cross-correlation FCS, the photon counting histogram and fluorescence intensity distribution analysis approaches, the raster scanning image correlation spectroscopy method, and the Number and Brightness technique. The physical principles underlying these approaches will be delineated, and each of the methods will be illustrated using examples from the literature.
Collapse
Affiliation(s)
- David M Jameson
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, 651 Ilalo St., BSB 222, Honolulu, HI 96813, USA
| | | | | |
Collapse
|
12
|
Marx N. C-peptide as a Mediator of Lesion Development in Early Diabetes—A Novel Hypothesis. Trends Cardiovasc Med 2008; 18:67-71. [DOI: 10.1016/j.tcm.2007.12.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2007] [Revised: 12/13/2007] [Accepted: 12/17/2007] [Indexed: 11/26/2022]
|
13
|
Briddon SJ, Hill SJ. Pharmacology under the microscope: the use of fluorescence correlation spectroscopy to determine the properties of ligand-receptor complexes. Trends Pharmacol Sci 2007; 28:637-45. [PMID: 18001848 PMCID: PMC2148440 DOI: 10.1016/j.tips.2007.09.008] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2007] [Revised: 09/05/2007] [Accepted: 09/07/2007] [Indexed: 02/04/2023]
Abstract
Recent years have revealed a high degree of structural organisation in the way in which cell-surface receptors and their associated signalling complexes interact at a molecular level. Fluorescence-based techniques have been at the forefront of methodologies used to investigate this organisation and dissect the pharmacology of drug–receptor interactions at the single-cell level. One such technique, fluorescence correlation spectroscopy (FCS), in conjunction with a fluorescent ligand or receptor, is capable of providing quantitative information about the number of receptors and their mobilities within small areas of the cell membrane that approach the size of some signalling domains. This article describes the use of FCS to perform subcellular quantitative pharmacology, with particular reference to G-protein-coupled receptors (GPCRs). In conjunction with other forms of fluctuation analysis, such as two-colour cross-correlation FCS and molecular brightness analysis, FCS provides the first opportunity to investigate the domain-specific nature of GPCR pharmacology.
Collapse
|
14
|
Hossain S, Grande M, Ahmadkhanov G, Pramanik A. Binding of the Alzheimer amyloid β-peptide to neuronal cell membranes by fluorescence correlation spectroscopy. Exp Mol Pathol 2007; 82:169-74. [PMID: 17398282 DOI: 10.1016/j.yexmp.2007.01.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2006] [Revised: 01/08/2007] [Accepted: 01/08/2007] [Indexed: 11/24/2022]
Abstract
The deposition of the Alzheimer amyloid beta-peptide (Abeta) fibrils in brain is a key step in Alzheimer's disease. The aggregated Abeta is found to be toxic to neurons since cells die when the aggregated Abeta is added to the cell culture medium. However, target of action of Abeta to cells is unknown. We have applied the fluorescence correlation spectroscopy (FCS) technique to study the existence of a receptor or target molecule for the Alzheimer amyloid beta-peptide (Abeta) in cultured human cerebral cortical neurons. FCS measurement of the fluorophore rhodamine-labeled Abeta (Rh-Abeta) shows diffusion times: 0.1 ms, 1.1 ms and 5.9 ms. Thus, 0.1 ms corresponds to the unbound Rh-Abeta, and 1.1 ms and 5.9 ms correspond to slowly diffusing complexes of Rh-Abeta bound to a kind of receptor or target molecule for Abeta. Addition of excess non-labeled Abeta is accompanied by a competitive displacement, showing that the Abeta binding is specific. Full saturation of the Abeta binding is obtained at nanomolar concentrations, indicating that the Abeta binding is of high affinity. The notion that using FCS we have found a kind of receptor or target molecule for Abeta makes an important point that Abeta kills cells possibly by affecting cell membranes via a receptor or target molecule. This study is of highly significance since it suggests that Abeta possibly affects neuronal cell membranes of Alzheimer patients via a receptor or target molecule.
Collapse
Affiliation(s)
- Shakil Hossain
- Department of Medical Biochemistry and Biophysics, Scheeles väg 2, Karolinska Institute, S-171 77 Stockholm, Sweden
| | | | | | | |
Collapse
|
15
|
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.
| | | | | |
Collapse
|
16
|
Sah H, Kim KS. Improvement of interfacial protein stability by CHAPS. Biotechnol Lett 2006; 28:567-70. [PMID: 16614894 DOI: 10.1007/s10529-006-0016-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2005] [Accepted: 01/18/2006] [Indexed: 10/24/2022]
Abstract
Emulsification of aqueous protein solutions in methylene chloride triggered the formation of water-insoluble aggregates at a water/methylene chloride interface. As a result, the amounts of beta-lactoglobulin and ovalbumin recovered in water were 36 and 44%, respectively. Addition of 5 mM: CHAPS in the aqueous phase raised the degree of beta-lactoglobulin recovery to 96%. Sodium taurocholate, however, failed to improve protein recovery. The stabilizing effect of CHAPS was also protein-specific and concentration-dependent: at >or=5 mM: , the surfactant caused unfolding of ovalbumin to make a water-soluble oligomer. CHAPS thus stabilizes proteins at an interface.
Collapse
Affiliation(s)
- Hongkee Sah
- College of Pharmacy, Ewha Womans University, 11-1 Daehyun-Dong, Seodaemun-Gu, Seoul 125-720, Korea.
| | | |
Collapse
|
17
|
Kobayashi Y, Naruse K, Hamada Y, Nakashima E, Kato K, Akiyama N, Kamiya H, Watarai A, Nakae M, Oiso Y, Nakamura J. Human proinsulin C-peptide prevents proliferation of rat aortic smooth muscle cells cultured in high-glucose conditions. Diabetologia 2005; 48:2396-401. [PMID: 16195866 DOI: 10.1007/s00125-005-1942-9] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2004] [Accepted: 06/29/2005] [Indexed: 12/01/2022]
Abstract
AIMS/HYPOTHESIS Proinsulin C-peptide is involved in several biological activities. However, the role of C-peptide in vascular smooth muscle cells is unclear. We therefore investigated its effects, in vascular smooth muscle cells in high-glucose conditions. METHODS Rat aortic smooth muscle cells were cultured with 5.5 or 20 mmol/l glucose with or without C-peptide (1 to 100 nmol/l) for 3 weeks. Proliferation activities, the protein expression of platelet-derived growth factor (PDGF)-beta receptor, the phosphorylation of p42/p44 mitogen-activated protein (MAP) kinases, and glucose uptake were measured. RESULTS The proliferation activities increased approximately three-fold under high-glucose conditions (p<0.05). C-peptide suppressed hyperproliferation activities that were induced by high glucose. This happened in a dose-dependent manner from 1 to 100 nmol/l of C-peptide. C-peptide (10 and 100 nmol/l) inhibited the increased protein expression of PDGF-beta receptor and the phosphorylation of p42/p44 MAP kinases that had been induced by high glucose (p<0.05). Furthermore, 100 nmol/l of C-peptide augmented the impaired glucose uptake in the high-glucose conditions. CONCLUSIONS/INTERPRETATION These observations suggest that C-peptide could prevent diabetic macroangiopathy by inhibiting smooth muscle cell growth and ameliorating glucose utilisation in smooth muscle cells. C-peptide may thus be a novel agent for treating diabetic macroangiopathy in patients with type 1 and type 2 diabetes.
Collapse
Affiliation(s)
- Y Kobayashi
- Division of Metabolic Diseases, Department of Internal Medicine, Nagoya University Graduate School of Medicine, Showa-ku, Nagoya, Japan
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
18
|
Skakun VV, Hink MA, Digris AV, Engel R, Novikov EG, Apanasovich VV, Visser AJWG. Global analysis of fluorescence fluctuation data. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2005; 34:323-34. [PMID: 15711810 DOI: 10.1007/s00249-004-0453-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2004] [Revised: 11/30/2004] [Accepted: 11/30/2004] [Indexed: 11/30/2022]
Abstract
Over the last decade the number of applications of fluorescence correlation spectroscopy (FCS) has grown rapidly. Here we describe the development and application of a software package, FCS Data Processor, to analyse the acquired correlation curves. The algorithms combine strong analytical power with flexibility in use. It is possible to generate initial guesses, link and constrain fit parameters to improve the accuracy and speed of analysis. A global analysis approach, which is most effective in analysing autocorrelation curves determined from fluorescence fluctuations of complex biophysical systems, can also be implemented. The software contains a library of frequently used models that can be easily extended to include user-defined models. The use of the software is illustrated by analysis of different experimental fluorescence fluctuation data sets obtained with Rhodamine Green in aqueous solution and enhanced green fluorescent protein in vitro and in vivo.
Collapse
Affiliation(s)
- Victor V Skakun
- Department of Systems Analysis, Belarusian State University, Minsk 220050, Belarus
| | | | | | | | | | | | | |
Collapse
|
19
|
Suzuki Y, Oka Y, Taniyama M, Murata C, Atsumi Y, Matsuoka K. A case of type 2 diabetes with high levels of plasma and urinary C-peptide. Diabetes Res Clin Pract 2004; 66 Suppl 1:S125-8. [PMID: 15563962 DOI: 10.1016/j.diabres.2004.05.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2003] [Accepted: 07/28/2003] [Indexed: 10/26/2022]
Abstract
By screening 204 diabetes patients, a male with age 38 was found to have increased C-peptide levels in plasma (over 6 ng/ml) and urine (430 microg/day), both of which were the highest among the screened subjects. He developed type 2 diabetes at age 31, without history of obesity (weight was 52 kg and height 170 cm). He had bilateral testicular atrophy. Fasting plasma glucose level was 160 mg/dl and HbA1c was 8% at age 38. There was hypertriglycemia (290-662 mg/dl). There were no abnormal peaks of IRI or CPR in the serum fractionated by gel filtration (Biogel P 30). Molar ratio of p-CPR/s-IRI was 10.8. Islet cell antibody, anti-insulin binding antibody and anti-insulin receptor antibody were negative. LSH and FSH were both elevated, and free testosterone was decreased. TSH and Leptin levels were elevated. Other laboratory data were within normal range. CT scan revealed fatty liver and horse-shoe kidney. These clinical pictures do not match the criteria to known syndromes associated with diabetes. Although the single case report is insufficient to discuss the C-peptide mechanism of action, this case may give us a hint to understand an aspect of the pathophysiology of C-peptide's bioactivity dysfunction.
Collapse
Affiliation(s)
- Y Suzuki
- Hoken Dohjin Medical Foundation, Tokyo, Japan.
| | | | | | | | | | | |
Collapse
|
20
|
Kuo YH, Chen TT. Specific cell surface binding sites shared by human Pro-IGF-I Eb-peptides and rainbow trout Pro-IGF-I Ea-4-peptide. Gen Comp Endocrinol 2003; 132:231-40. [PMID: 12812770 DOI: 10.1016/s0016-6480(03)00089-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Human pro-IGF-I Eb-peptide (hEb) and rainbow trout pro-IGF-I Ea-4-peptide (rtEa-4) have recently been shown to share unique biological activities [Gen. Comp. Endocrinol. 126 (2002) 342; Cell. Exp. Cell. Res. 280 (2002) 75]. To further understand the action mechanism of these proteins, we studied the binding properties of hEb-peptide and rtEa-4-peptide to intact human neuroblastoma cells (SK-N-F1) and membrane preparations. Human Eb-peptide and rtEa-4-peptide bind to a high-affinity binding site with an apparent dissociation constant of 3.2+/-1.9 x 10(-11) and 2.9+/-1.8 x 10(-11)M, respectively. Homologous displacement assay demonstrated the presence of a second binding site with an IC(50) of 4.8+/-2.6 x 10(-6)M for hEb-peptide and 2.1+/-0.6 x 10(-6)M for rtEa-4-peptide, respectively. Competition assays showed that hEb-peptide and rtEa-4-peptide shared common binding sites, distinct from those for IGF-I and insulin. In addition, chemical cross-linking studies revealed two specific binding complexes. Our findings support the notion that the initial step of pro-IGF-I E-peptide action is mediated through the interaction with conserved and specific putative membrane receptors on neuroblastoma cells.
Collapse
Affiliation(s)
- Ya-Huei Kuo
- Department of Molecular and Cell Biology and Biotechnology Center, University of Connecticut, 75 North Eagleville Road, U-3044, Storrs, CT 06269-3044, USA
| | | |
Collapse
|
21
|
Kitamura T, Kimura K, Jung BD, Makondo K, Sakane N, Yoshida T, Saito M. Proinsulin C-peptide activates cAMP response element-binding proteins through the p38 mitogen-activated protein kinase pathway in mouse lung capillary endothelial cells. Biochem J 2002; 366:737-44. [PMID: 12059784 PMCID: PMC1222821 DOI: 10.1042/bj20020344] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2002] [Revised: 06/05/2002] [Accepted: 06/11/2002] [Indexed: 11/17/2022]
Abstract
Proinsulin C-peptide has been reported to have some biological activities and to be possibly involved in the development of diabetic microangiopathy. In the present study, we examined the effects of C-peptide on the mitogen-activated protein kinase pathway in LEII mouse lung capillary endothelial cells. Stimulation of the cells with C-peptide increased both p38 mitogen-activated protein kinase (p38MAPK) and extracellular signal-regulated kinase (ERK1/2) activities and activity-related site-specific phosphorylation of the respective kinases in a concentration-dependent manner, but failed to activate c-Jun N-terminal kinase. Stimulation of the cells with C-peptide also induced site-specific phosphorylation of cAMP response element (CRE)-binding protein (CREB)/activating transcription factor 1 (ATF1), and thereby binding of these transcription factors to CRE. Among three CREB kinases tested, phosphorylation of mitogen-activated protein kinase-activated protein kinase 2 (MAPKAP-K2) was induced after stimulation with C-peptide. The phosphorylation of CREB, ATF1 and MAPKAP-K2 were inhibited by SB203580, a p38MAPK inhibitor, but not by PD98059, an ERK kinase inhibitor. These results indicate that C-peptide activates p38MAPK followed by MAPKAP-K2 to enhance DNA-CREB/ATF1 interactions.
Collapse
Affiliation(s)
- Takanori Kitamura
- Laboratory of Biochemistry, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan
| | | | | | | | | | | | | |
Collapse
|
22
|
Johansson J, Ekberg K, Shafqat J, Henriksson M, Chibalin A, Wahren J, Jörnvall H. Molecular effects of proinsulin C-peptide. Biochem Biophys Res Commun 2002; 295:1035-40. [PMID: 12135597 DOI: 10.1016/s0006-291x(02)00721-0] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The proinsulin C-peptide has been held to be merely a by-product in insulin biosynthesis, but recent reports show that it elicits both molecular and physiological effects, suggesting that it is a hormonally active peptide. Specific binding of C-peptide to the plasma membranes of intact cells and to detergent-solubilised cells has been shown, indicating the existence of a cell surface receptor for C-peptide. C-peptide elicits a number of cellular responses, including Ca(2+) influx, activation of mitogen-activated protein (MAP) kinases, of Na(+),K(+)-ATPase, and of endothelial NO synthase. The pentapeptide EGSLQ, corresponding to the C-terminal five residues of human C-peptide, mimics several of the effects of the full-length peptide. The pentapeptide displaces cell membrane-bound C-peptide, elicits transient increase in intracellular Ca(2+) concentration and stimulates MAP kinase signalling pathways and Na(+),K(+)-ATPase. The Glu residue of the pentapeptide is essential for displacement of the full-length C-peptide, and free Glu can partly displace bound C-peptide, suggesting that charge interactions are important for receptor binding. Many C-peptide effects, such as phosphorylation of MAP-kinases ERK 1 and 2, stimulation of Na(+),K(+)-ATPase and increases in intracellular calcium concentrations are inhibited by pertussis toxin, supporting interaction of C-peptide with a G-protein-coupled receptor. However, all C-peptide effects cannot be explained in this manner, and it is possible that additional interactions are involved. Combined, the available observations show that C-peptide is biologically active and suggest a molecular model for its physiological effects.
Collapse
Affiliation(s)
- Jan Johansson
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
| | | | | | | | | | | | | |
Collapse
|
23
|
Pramanik A, Ekberg K, Zhong Z, Shafqat J, Henriksson M, Jansson O, Tibell A, Tally M, Wahren J, Jörnvall H, Rigler R, Johansson J. C-Peptide Binding to Human Cell Membranes: Importance of Glu27. Biochem Biophys Res Commun 2001; 284:94-8. [PMID: 11374876 DOI: 10.1006/bbrc.2001.4917] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In addition to its established role in proinsulin folding, C-peptide has a function in regulation of cellular activity. The 31-residue peptide influences renal, vascular, and metabolic functions in patients with insulin-dependent diabetes mellitus. Binding to cells has been demonstrated for C-peptide, which can be displaced by its C-terminal pentapeptide. We have now used fluorescence correlation spectroscopy to investigate structural requirements on the pentapeptide part for C-peptide binding. All pentapeptide residues, E(27)GSLQ(31), were individually replaced with Ala and the capacity of the resulting peptides to displace rhodamine-labelled full-length human C-peptide from human renal tubular cell membranes was determined. This showed that Glu27 is essential for displacement, while replacement of Gly28 with Ala has little effect, and replacement of any of the three most C-terminal residues had intermediate effects. Morevover, free Glu displaces full-length C-peptide to about 50%, while free Ala, C-peptide(1-26), and the truncated pentapeptide, corresponding to the tetrapeptide G(28)SLG(31), have no displacing capacity. The peptides EVARQ (corresponding to the rat C-terminal pentapeptide) and ELGGGPGAG (corresponding to positions 11-19 of human C-peptide) do not displace human C-peptide. These results indicate that Glu27 of C-peptide is critically involved in binding to cellular targets.
Collapse
Affiliation(s)
- A Pramanik
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, SE-171 77, Sweden
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
24
|
Pramanik A, Rigler R. Ligand-Receptor Interactions in the Membrane of Cultured Cells Monitored by Fluorescence Correlation Spectroscopy. Biol Chem 2001; 382:371-8. [PMID: 11347883 DOI: 10.1515/bc.2001.045] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
We investigated the specific binding of epidermal growth factor (EGF) to its membrane-bound receptors in cultured cells. The specificity of the binding was attested by the consistent displacement of bound rhodamine-labeled EGF (Rh-EGF) following addition of 1000-fold molar excess of unlabeled EGF. The binding specificity of EGF was further confirmed when vascular EGF was unable to displace Rh-EGF binding, demonstrating no cross-reaction. Evidence for the specific interactions was verified by an equilibrium saturation binding experiment. EGF binding to the cell membranes is saturated at nanomolar concentration. The Scatchard plots show a binding process with K(ass) of 1.5 x 10(9) M(-1). The dissociation kinetics follow a single exponential function characteristic for a relatively slow dissociation process with k(diss) = 2.9 x 10(-4) s(-1). The appearance of two binding complexes through the distribution of diffusion times may suggest that these are representatives of two different forms or subtypes of EGF receptors. This study is of pharmaceutical significance as it provides evidence that fluorescence correlation spectroscopy can be used as a rapid technique for studying ligand-receptor interactions in cell cultures. This is a step forward toward large-scale drug screening in cell cultures.
Collapse
Affiliation(s)
- A Pramanik
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | | |
Collapse
|