University of Pittsburgh Department of Cell Biology

  • Research

    Our laboratory studies pancreatic β cell biology focused on insulin secretory granule proteins regulating trafficking and exocytic release, and β cell proliferation and anti-oxidant pathways underlying its adaption to oxidative stress in the setting of diabetes mellitus. In pancreatic β cells, the KATP channel brings insulin secretion under the control of blood glucose levels. Our major goal is to establish the molecular mechanisms underlying how ATP binding to the KATP channel signaling changes in glucose metabolism, in turn, signals commensurate changes in insulin granule trafficking and exocytosis. Normally, the fraction of time the KATP channel spends in the inhibited state determines insulin secretory rates. When this regulation goes awry, serious complications at the whole-organism level lead to diabetes and other diseases. (1) We have demonstrated how ATP binding to the Kir6.2 subunit of the KATP channel electrostatically couples to the transmembrane domain to cause gate closure. One of the positions of the KATPchannel required for this signaling is mutated in the conserved position of the human KATP channel in permanent neonatal diabetes (PNDM). (2) We have also combined confocal fluorescence microscopy and a novel molecular strategy to visualize insulin secretion in live β cells. The Ins-C-GFP reporter has exploded the ability to look inside live insulin secreting β cells to study glucose-stimulated insulin granule trafficking and exocytosis. Using this approach, we have localized KATP channels to insulin secretory granules. (3) Currently, we are using fluorescent reporters of oxidative stress to explore glucolipotoxicity and its reversal by anti-oxidant and proliferative pathways in pancreatic β cells. (4) Most recently, we are interrogating the role of granule KATP channels and its small molecule and protein ligands in regulating insulin secretion and β cell proliferation. Trainees in our laboratory are mentored in the exploration of scientific reasoning in health and disease by applying molecular genetics, confocal live-cell fluorescence imaging, native fluorescent protein gels, and western blotting, with insulin, stress, and cell proliferation ELISAs, to understand β cell biology in health and disease.

  • Publications

    1. Luppi P, Drain N, To R, Stolz D, Wallace C, Watkins S, Drain P. Autocrine C-peptide protects INS1 β cells against palmitic acid-induced oxidative stress in peroxisomes by inducing catalase.. Endocrinol Diabetes Metab. 2020 Jul;3(3):e00147. doi: 10.1002/edm2.147. PubMed PMID: 32704568;
    2. Luppi P, Drain P. Uncoupling a unique couple by chopping off one of its tails: insights into the KATP channels of the heart and pancreas.. J Physiol. 2018 Dec;596(24):6135-6136. doi: 10.1113/JP277099. PubMed PMID: 30387493;
    3. Brüning D, Reckers K, Drain P, Rustenbeck I. Glucose but not KCl diminishes submembrane granule turnover in mouse beta-cells.. J Mol Endocrinol. 2017 Oct;59(3):311-324. doi: 10.1530/JME-17-0063. PubMed PMID: 28765259;
    4. Luppi P, Drain P. C-peptide antioxidant adaptive pathways in β cells and diabetes.. J Intern Med. 2017 Jan;281(1):7-24. doi: 10.1111/joim.12522. PubMed PMID: 27251308;
    5. Luppi P, Drain P. Autocrine C-peptide mechanism underlying INS1 beta cell adaptation to oxidative stress.. Diabetes Metab Res Rev. 2014 Oct;30(7):599-609. doi: 10.1002/dmrr.2528. PubMed PMID: 24459093;
    6. Drain P. ATP and sulfonylurea linkage in the K(ATP) channel solves a diabetes puzzler.. Diabetes. 2013 Nov;62(11):3666-8. doi: 10.2337/db13-1194. PubMed PMID: 24158995;
    7. Chu KY, Briggs MJ, Albrecht T, Drain PF, Johnson JD. Differential regulation and localization of carboxypeptidase D and carboxypeptidase E in human and mouse β-cells.. Islets. 2011 Jul-Aug;3(4):155-65. . PubMed PMID: 21628999;
    8. Stefan M, Simmons RA, Bertera S, Trucco M, Esni F, Drain P, Nicholls RD. Global deficits in development, function, and gene expression in the endocrine pancreas in a deletion mouse model of Prader-Willi syndrome.. Am J Physiol Endocrinol Metab. 2011 May;300(5):E909-22. doi: 10.1152/ajpendo.00185.2010. PubMed PMID: 21343540;
    9. Geng X, Lou H, Wang J, Li L, Swanson AL, Sun M, Beers-Stolz D, Watkins S, Perez RG, Drain P. α-Synuclein binds the K(ATP) channel at insulin-secretory granules and inhibits insulin secretion.. Am J Physiol Endocrinol Metab. 2011 Feb;300(2):E276-86. doi: 10.1152/ajpendo.00262.2010. PubMed PMID: 20858756;
    10. Luppi P, Geng X, Cifarelli V, Drain P, Trucco M. C-peptide is internalised in human endothelial and vascular smooth muscle cells via early endosomes.. Diabetologia. 2009 Oct;52(10):2218-28. doi: 10.1007/s00125-009-1476-7. PubMed PMID: 19662378;
    11. Geng X, Li L, Bottino R, Balamurugan AN, Bertera S, Densmore E, Su A, Chang Y, Trucco M, Drain P. Antidiabetic sulfonylurea stimulates insulin secretion independently of plasma membrane KATP channels.. Am J Physiol Endocrinol Metab. 2007 Jul;293(1):E293-301. . PubMed PMID: 17405830;
    12. Michael DJ, Xiong W, Geng X, Drain P, Chow RH. Human insulin vesicle dynamics during pulsatile secretion.. Diabetes. 2007 May;56(5):1277-88. . PubMed PMID: 17317765;
    13. Nakahira K, Kim HP, Geng XH, Nakao A, Wang X, Murase N, Drain PF, Wang X, Sasidhar M, Nabel EG, Takahashi T, Lukacs NW, Ryter SW, Morita K, Choi AM. Carbon monoxide differentially inhibits TLR signaling pathways by regulating ROS-induced trafficking of TLRs to lipid rafts.. J Exp Med. 2006 Oct 2;203(10):2377-89. . PubMed PMID: 17000866;
    14. Sun F, Zhang R, Gong X, Geng X, Drain PF, Frizzell RA. Derlin-1 promotes the efficient degradation of the cystic fibrosis transmembrane conductance regulator (CFTR) and CFTR folding mutants.. J Biol Chem. 2006 Dec 1;281(48):36856-63. . PubMed PMID: 16954204;
    15. Li L, Geng X, Yonkunas M, Su A, Densmore E, Tang P, Drain P. Ligand-dependent linkage of the ATP site to inhibition gate closure in the KATP channel.. J Gen Physiol. 2005 Sep;126(3):285-99. . PubMed PMID: 16129775;
    16. Michael DJ, Geng X, Cawley NX, Loh YP, Rhodes CJ, Drain P, Chow RH. Fluorescent cargo proteins in pancreatic beta-cells: design determines secretion kinetics at exocytosis.. Biophys J. 2004 Dec;87(6):L03-5. . PubMed PMID: 15516519;
    17. Drain P, Geng X, Li L. Concerted gating mechanism underlying KATP channel inhibition by ATP.. Biophys J. 2004 Apr;86(4):2101-12. . PubMed PMID: 15041650;
    18. Bertera S, Geng X, Tawadrous Z, Bottino R, Balamurugan AN, Rudert WA, Drain P, Watkins SC, Trucco M. Body window-enabled in vivo multicolor imaging of transplanted mouse islets expressing an insulin-Timer fusion protein.. Biotechniques. 2003 Oct;35(4):718-22. . PubMed PMID: 14579736;
    19. Geng X, Li L, Watkins S, Robbins PD, Drain P. The insulin secretory granule is the major site of K(ATP) channels of the endocrine pancreas.. Diabetes. 2003 Mar;52(3):767-76. . PubMed PMID: 12606519;

     

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