Diabetes results from a deficiency of functional beta cells. Studies aimed at analyzing how key growth factors/hormones and intracellular signaling molecules can increase beta cell proliferation, prevent beta cell loss and enhance insulin release are essential for future therapeutic approaches for diabetes. In this proposal, we focus on one of the important downstream targets of phosphatidylinositol 3'-kinase, the atypical protein kinase C (PKC) signaling pathway. Activation of this pathway enhances proliferation, function and survival in numerous cell types. Importantly, in the beta cell, we have shown that growth factors and nutrients such as glucose activate the atypical isoform PKC zeta (?). However, the role of this signaling pathway in the beta cell is still in its early infancy. Is PKC ? crucial in glucose-mediated beta cell proliferation and function in vitro and in vivo? Our preliminary results indicate that glucose indeed requires PKC ? to increase mouse and human beta cell proliferation in vitro. Furthermore, constitutive activation of PKC ? in beta cells results in increased mouse and human beta cell proliferation and insulin secretion in vitro in mouse islets. Does it occur in vivo as well? In the current proposal, using a novel four-day glucose infusion model and transgenic mice expressing dominant-negative or constitutively active PKC ? isoforms in the beta cell, we will fully characterize the role of PKC ? on basal and glucose-mediated beta cell growth and function and its therapeutic potential in an islet transplant setting. To develop this project, we will implement the following Specific Aims: 1. To define the role of PKC ? in glucose-mediated beta cell proliferation in vivo. 2. To assess the effect of constitutive activation of PKC ? in beta cell proliferation, function and survival in vitro and in vivo. 3. To evaluate the efficacy of constitutive activation of PKC ? in improving mouse and human islet transplant outcomes in a marginal mass model of islet transplantation in SCID mice. Our preliminary results demonstrate a central and critical role for PKC ? signaling in beta cell growth and function. Thus, the proposed studies will provide invaluable information on the impact of PKC ? on beta cell proliferation, function, survival and islet transplantation. If translated into humans, constitutive activation of PKC ? may be an attractive therapeutic strategy for expanding beta cell mass and function in patients with diabetes.
We have shown that growth factors and nutrients such as glucose activate atypical PKC zeta (?) in beta cells. Activation of PKC ? results in increased mouse and, most importantly, human beta cell proliferation in vitro. Studies in the current proposal will decipher: (i) the effects of PKC ? in the beta cell in vivo;(ii) the mechanisms underlying PKC ? effects in the beta cell;and, (iii) its therapeutic potential in an islet transplant setting. The proposed studies will provide invaluable information on the impact of PKC ? on beta cell proliferation, function, survival and islet transplantation. If translated into humans, activation of PKC ? may be an attractive therapeutic strategy for expanding beta cell mass and function in patients with diabetes.
|Stamateris, Rachel E; Sharma, Rohit B; Kong, Yahui et al. (2016) Glucose Induces Mouse ?-Cell Proliferation via IRS2, MTOR, and Cyclin D2 but Not the Insulin Receptor. Diabetes 65:981-95|
|Lakshmipathi, Jayalakshmi; Alvarez-Perez, Juan Carlos; Rosselot, Carolina et al. (2016) PKC? Is Essential for Pancreatic ?-Cell Replication During Insulin Resistance by Regulating mTOR and Cyclin-D2. Diabetes 65:1283-96|
|Ljubicic, Sanda; Polak, Klaudia; Fu, Accalia et al. (2015) Phospho-BAD BH3 mimicry protects ? cells and restores functional ? cell mass in diabetes. Cell Rep 10:497-504|
|Wang, Peng; Alvarez-Perez, Juan-Carlos; Felsenfeld, Dan P et al. (2015) A high-throughput chemical screen reveals that harmine-mediated inhibition of DYRK1A increases human pancreatic beta cell replication. Nat Med 21:383-8|
|Wang, Peng; Fiaschi-Taesch, Nathalie M; Vasavada, Rupangi C et al. (2015) Diabetes mellitus--advances and challenges in human ?-cell proliferation. Nat Rev Endocrinol 11:201-12|
|Stewart, Andrew F; Hussain, Mehboob A; García-Ocaña, Adolfo et al. (2015) Human ?-cell proliferation and intracellular signaling: part 3. Diabetes 64:1872-85|
|Alvarez-Perez, Juan Carlos; Ernst, Sara; Demirci, Cem et al. (2014) Hepatocyte growth factor/c-Met signaling is required for ?-cell regeneration. Diabetes 63:216-23|
|Bernal-Mizrachi, Ernesto; Kulkarni, Rohit N; Scott, Donald K et al. (2014) Human ?-cell proliferation and intracellular signaling part 2: still driving in the dark without a road map. Diabetes 63:819-31|
|Alvarez-Perez, Juan C; Rosa, Taylor C; Casinelli, Gabriella P et al. (2014) Hepatocyte growth factor ameliorates hyperglycemia and corrects ?-cell mass in IRS2-deficient mice. Mol Endocrinol 28:2038-48|
|García-Ocaña, Adolfo; Stewart, Andrew F (2014) ""RAS""ling ? cells to proliferate for diabetes: why do we need MEN? J Clin Invest 124:3698-700|
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