Abstract
Munc13-1 may be a key factor in regulating insulin exocytosis, but its exact expression and role have not been clarified yet, especially during pancreatic development. We attempted to investigate the expression and function of Munc13-1 during embryonic pancreatic development in rats and determine the effects on insulin secretion. In the present study, pancreata of rats at embryonic day 12.5 (E12.5), E15.5, E18.5, new-born, 21 after birth (P21), and adult stage were dissected under microscope. The rat model of intrauterine growth retardation (IUGR) was made by 50% calorie restriction in pregnant rats from gestational day 15 until term. The expression of Munc13-1 and insulin secretion was studied by the techniques of RT-PCR, real-time PCR, Western blot, and enzyme-linked immunosorbent assay. Immunohistochemistry and immunofluorescence were used to define the location of Munc13-1. We found that Munc13-1 was located at islet along with insulin. Insulin- and Munc13-1-specific mRNA were not detected until E12.5 and E15.5, respectively, and increased with the development of the fetus. Western blot showed that Munc13-1 was low at E15.5 and E18.5 and increased later. The blood insulin level and Munc13-1 were reduced simultaneously in IUGR newborn rats compared with normal ones. These results suggest that Munc13-1 exists in pancreas islets during fetus development and its deficiency in the pancreas, as occurs in IUGR, was in accordance with decreased blood insulin level. Munc13-1 may play an essential role in insulin exocytosis.
Similar content being viewed by others
References
Rorsman P, Renström E. Insulin granule dynamics in pancreatic beta cells. Diabetologia 2003, 46: 1029–45.
Kim SK, Hebrok M. Intercellular signals regulating pancreas development and function. Genes Dev 2001, 15: 111–27.
Lang J. Molecular mechanisms and regulation of insulin exocytosis as a paradigm of endocrine secretion. Eur J Biochem 1999, 259: 3–17.
Gu G, Wells JM, Dombkowski D, Preffer F, Aronow B, Melton DA. Global expression analysis of gene regulation pathways during endocrine pancreatic development. Development 2004, 131: 165–79.
Augustin I, Rosenmund C, Südhof TC, Brose N. Munc13-1 is essential for fusion competence of glutamatergic synaptic vesicles. Nature 1999, 400: 457–61.
Varoqueaux F, Sigler A, Rhee JS, et al. Total arrest of spontaneous and evoked synaptic transmission but normal synaptogenesis in the absence of Munc13-mediated vesicle priming. Proc Natl Acad Sci U S A 2002, 99: 9037–42.
Holemans K, Aerts L, Van Assche FA. Lifetime consequences of abnormal fetal pancreatic development. J Physiol 2003, 547: 11–20.
Varoqueaux F, Sons MS, Plomp JJ, Brose N. Aberrant morphology and residual transmitter release at the Munc13-deficient mouse neuromuscular synapse. Mol Cell Biol 2005, 25: 5973–84.
Sheu L, Pasyk EA, Ji J, et al. Regulation of insulin exocytosis by Munc13-1. J Biol Chem 2003, 30: 27556–663.
Gladycheva SE, Ho CS, Lee YY, Stuenkel EL. Regulation of syntaxin 1A-Munc18 complex for SNARE pairing in HEK293 cells. J Physiol 2004, 558: 857–71.
Cheviet S, Coppola T, Haynes LP, Burgoyne RD, Regazzi R. The Rab-binding protein Noc2 is associated with insulin-containing secretory granules and is essential for pancreatic β-cell exocytosis. Mol Endocrinol 2004, 18: 117–26.
Kwan EP, Xie L, Sheu L, et al. Munc13-1 deficiency reduces insulin secretion and causes abnormal glucose tolerance. Diabetes 2006, 55: 1421–9.
Kang L, He Z, Xu P, et al. Munc13-1 is required for the sustained release of insulin from pancreatic beta cells. Cell Metab 2006, 3: 463–8.
Yuan QX, Liu C, Teng LP. Global expression analysis during late stage of embryonic pancreatic development of rats with microarray technique. J Nangjing Med Univ 2006, 20: 1–25.
Boitard C, Cerasi E, Efendic S, Henquin JC, Steiner DF, Ferrannini E. Novel factors in the regulation of β-cell function. Diabetes 2004, 53(Suppl 1): S1–3.
Ohara-Imaizumi M, Ohtsuka T, Matsushima S, et al. ELKS, a protein structurally related to the active zone-associated protein CAST, is expressed in pancreatic beta cells and functions in insulin exocytosis: interaction of ELKS with exocytotic machinery analyzed by total internal reflection fluorescence microscopy. Mol Biol Cell 2005, 16: 3289–300.
Yaekura K, Julyan R, Wicksteed BL, et al. Insulin secretory deficiency and glucose intolerance in Rab3A null mice. J Biol Chem 2003, 278: 9715–21.
Dulubova I, Lou X, Lu J. A Munc13/RIM/Rab3 tripartite complex: from priming to plasticity? EMBO J 2005, 24: 2839–50.
Hill DJ, Duvillié B. Pancreatic development and adult diabetes. Pediatr Res 2000, 48: 269–74.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Yuan, Q.X., Teng, L.P., Zhou, J.Y. et al. Characterization of Munc13-1 and insulin secretion during pancreatic development in rats. J Endocrinol Invest 31, 630–635 (2008). https://doi.org/10.1007/BF03345615
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/BF03345615