A New Cell Secreting Insulin
IR@IICB: CSIR-Indian Institute of Chemical Biology, Kolkata
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Title |
A New Cell Secreting Insulin
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Creator |
Roy, Sib Sankar
Mukherjee, Mahua Bhattacharya, Samir Mandal, Chhabinath Kumar, L. Ravi Dasgupta, Subrata Bandyopadhyay, I Wakabayashi, Katsumi |
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Subject |
Cell Biology & Physiology
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Description |
The pancreatic �-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 �-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 SDSPAGE,
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 structurefunction
relationship between AdpInsl and mammalian �-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 �-cell insulin. (Endocrinology 144:
1585–1593, 2003
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Date |
2003
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Type |
Article
PeerReviewed |
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Format |
application/pdf
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Identifier |
http://www.eprints.iicb.res.in/597/1/ENDOCRINOLOGY%2C_144(_4)%2C_1585%2D1593[73].pdf
Roy, Sib Sankar and Mukherjee, Mahua and Bhattacharya, Samir and Mandal, Chhabinath and Kumar, L. Ravi and Dasgupta, Subrata and Bandyopadhyay, I and Wakabayashi, Katsumi (2003) A New Cell Secreting Insulin. Endocrinology, 144 (4). pp. 1585-1593. |
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Relation |
http://dx.doi.org/10.1210/en.2002-220350
http://www.eprints.iicb.res.in/597/ |
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