Regulation of Ca(2+)-entry in pancreatic α-cell line by transient receptor potential melastatin 4 plays a vital role in glucagon release.
Elevation in the intracellular Ca(2+) concentration stimulates glucagon secretion from pancreatic α-cells. The Transient Receptor Potential Melastatin 4 channel (TRPM4) is critical for Ca(2+) signaling. However, its role in glucagon secreting α-cells has not been investigated. We identified TRPM4 gene expression and protein in the αTC1-6 cell line using RT-PCR and immunocytochemistry. Furthermore, we performed a detailed biophysical characterization of the channel using the patch-clamp technique to confirm that currents typical for TRPM4 were present in αTC1-6 cells. To investigate TRPM4 function, we generated a stable knockdown clone using shRNA and a lentiviral vector. Inhibition of TRPM4 significantly reduced the responses to different agonists during Ca(2+) imaging analysis with Fura-2AM. The reduction in the magnitude of Ca(2+) signals resulted in decreased glucagon secretion. These results suggested that depolarization by TRPM4 may play an important role in controlling glucagon secretion from α-cells and perhaps glucose homeostasis.
Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Skip Bertman Drive, Baton Rouge, LA 70803, USA.
P L
PL
Nelson
O
O
Zolochevska
M L
ML
Figueiredo
A
A
Soliman
W H
WH
Hsu
J M
JM
Feng
H
H
Zhang
H
H
Cheng
D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology*; D002118:Calcium / Q000494:pharmacology; D020013:Calcium Signaling; D002460:Cell Line; D006224:Cricetinae; D017930:Genes, Reporter; D005934:Glucagon / Q000378:metabolism*; D050416:Glucagon-Secreting Cells / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008536:Meglumine / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D018408:Patch-Clamp Techniques; D034622:RNA Interference; D051381:Rats; D050053:TRPM Cation Channels / Q000819:agonists / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
D050053:TRPM Cation Channels; C476766:TRPM4 protein, mouse; D001127:Arginine Vasopressin; D049452:Green Fluorescent Proteins; D008536:Meglumine; D005934:Glucagon; D002118:Calcium