This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Roy, S. S. Articles by Wakabayashi, K. Search for Related Content PubMed PubMed Citation Articles by Roy, S. S. Articles by Wakabayashi, K.

A New Cell Secreting Insulin

Indian Institute of Chemical Biology (S.S.R., M.M., S.B., C.N.M.), Calcutta 700032, India; and School of Life Science, Department of Zoology, Visva Bharati University (L.R.K., S.D., I.B.), Santiniketan 731235, India; and Institute for Molecular and Cellular Regulation, Gunma University (K.W.), Maebashi 371-0847, Japan

Address all correspondence and requests for reprints to: Prof. Samir Bhattacharya, Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Calcutta 700032, India. E-mail: samir{at}iicb.res.in.

The pancreatic ß-cell is the only cell in animals that expresses the insulin gene and secretes insulin protein. We have found copious release of immunoreactive and bioactive insulin into the medium from the primary culture of carp adipocytes. Glucose augmented this release to more than 2-fold, and glucose transporter, Glut2, was detected in these cells. These all reflect characteristics of a pancreatic ß-cell. The expression of the adipocyte-specific flotillin gene, the presence of peroxisomal proliferator-activated receptor and Glut4, and the colocalization of insulin and leptin confirmed the identity of these cells as adipocytes. Purified carp adipocyte insulin (AdpInsl) comigrated with porcine and bovine insulin in SDS-PAGE, indicating the similarity of their molecular sizes (5.5 kDa). AdpInsl strongly reduced hyperglycemia in streptozotocin-induced diabetic rats. It also stimulated significantly higher glucose uptake in carp and hamster adipocytes than porcine insulin. Adipocyte RNA hybridized with rat and zebrafish insulin cDNA showing the expression of the insulin gene in this cell. Using oligonucleotide primers designed on the basis of conserved insulin domain, AdpInsl cDNA was reverse transcribed, cloned, and sequenced. The deduced amino acid sequence of AdpInsl A and B chain exhibited 98% homology with zebrafish and more than 70% homology with human, porcine, and murine insulin. To understand the structure-function relationship between AdpInsl and mammalian ß-cell insulin, we have analyzed the amino acid sequences and three-dimensional structure of AdpInsl. In the critical determinant segment for receptor binding, AdpInsl has His at the A8 position instead of Thr in human and porcine insulin, and this attributed greater biological activity to AdpInsl. Our results show that carp adipocyte is a unique cell. As an insulin target cell it can express the insulin gene and secrete highly active insulin protein; thus, it may serve as a natural alternative to pancreatic ß-cell insulin.

This article has been cited by other articles:

				E. J. Flynn III, C. M. Trent, and J. F. Rawls Ontogeny and nutritional control of adipogenesis in zebrafish (Danio rerio) J. Lipid Res., August 1, 2009; 50(8): 1641 - 1652. [Abstract] [Full Text] [PDF]

				S. Paul, D. Mukherjee, K. Pramanick, S. Kundu, S P Bhattacharyya, P. De, and D. Mukherjee Stimulation of salmon calcitonin on secretion of 17{beta}-estradiol by the ovarian follicles of common carp, Cyprinus carpio J. Endocrinol., February 1, 2008; 196(2): 413 - 424. [Abstract] [Full Text] [PDF]

				M. O. Huising, E. J. W. Geven, C. P. Kruiswijk, S. B. Nabuurs, E. H. Stolte, F. A. T. Spanings, B. M. L. Verburg-van Kemenade, and G. Flik Increased Leptin Expression in Common Carp (Cyprinus carpio) after Food Intake But Not after Fasting or Feeding to Satiation Endocrinology, December 1, 2006; 147(12): 5786 - 5797. [Abstract] [Full Text] [PDF]

				S. K. Saha, P. Ghosh, A. Konar, S. Bhattacharya, and S. S. Roy Differential Expression of Procollagen Lysine 2-Oxoglutarate 5-Deoxygenase and Matrix Metalloproteinase Isoforms in Hypothyroid Rat Ovary and Disintegration of Extracellular Matrix Endocrinology, July 1, 2005; 146(7): 2963 - 2975. [Abstract] [Full Text] [PDF]