438-P: Glucose-Dependent Insulinotropic Polypeptide Prevents Palmitate-Induced Apoptosis, but Not Autophagy and Stress Kinase Activation in Human Cardiac Progenitor Cells

Introduction & Objective: The gut incretin hormone glucose-dependent insulinotropic polypeptide (GIP) plays key roles in metabolic regulation. Evidence supports a beneficial role of GIP signaling on cardiometabolic health; however, effects of GIP on human cardiac progenitor cells (hCPC) are not known. This study investigates the ability of the saturated fatty acid palmitate to induce apoptosis, autophagy, and stress kinase activation in hCPC, and the potential effects of GIP on palmitate-induced abnormalities. Methods: hCPC were obtained from control subjects undergoing elective cardiac surgery. Expression of GIP receptor was evaluated by quantitative real-time PCR and immunoblotting. hCPC were treated with different doses (1-10-100 nM) of GIP for different times (up to 120 min) and were exposed to 0.25 mM palmitate for 16 h. Apoptosis was assessed by ELISA assay. LC3II protein levels, as well as CREB (S133), p44/p42 MAPK (T202/Y204), c-Jun (S63), and p38 MAPK (T180/Y182) phosphorylation levels were assessed by immunoblotting. Results: GIP receptor was expressed in hCPC at both mRNA and protein levels. Exposure of hCPC to 10 nM GIP for 20 min induced CREB (S133) and p44/p42 MAPK (T202/Y204) phosphorylation (p<0.05). Treatment of hCPC with palmitate induced c-Jun, a downstream transcription factor of JNK 1/2, as well as p38 MAPK phosphorylation, apoptosis, and autophagy (p<0.05). Pretreatment with 10 nM GIP for 1 h prevented palmitate-induced apoptosis (p<0.05), but not autophagy. Interestingly, palmitate effects on stress kinase activation were not prevented when hCPC were pretreated with GIP. Conclusion: These studies show for the first time that GIP has direct effects on hCPC preventing palmitate-induced apoptosis, but not autophagy, through a signaling pathway independent of JNK 1/2 and p38 MAPK. Hence, GIP signaling might protect hCPC from selective lipotoxicity-induced metabolic abnormalities. Disclosure I. Calderoni: None. R. Doria: None. C. Caccioppoli: None. C. Colabufo: None. V. Genchi: None. G. Palma: None. G. Santarpino: None. A.D. Milano: None. T. Bottio: None. A. Leonardini: None. A. Natalicchio: Speaker's Bureau; AstraZeneca, Novo Nordisk, Sanofi, Eli Lilly and Company. S. Perrini: None. A. Cignarelli: None. F. Giorgino: Consultant; AstraZeneca, Boehringer-Ingelheim, Eli Lilly and Company, LifeScan Diabetes Institute, Merck Sharp & Dohme Corp., Medtronic, Novo Nordisk, Roche Diabetes Care, Sanofi. Research Support; Eli Lilly and Company, Roche Diabetes Care. L. Laviola: Speaker's Bureau; A. Menarini Diagnostics, Abbott, AlfaSigma. Advisory Panel; Boehringer-Ingelheim, Eli Lilly and Company, Medtronic, Novo Nordisk. Speaker's Bureau; AstraZeneca. Advisory Panel; Roche Diabetes Care, Sanofi. Speaker's Bureau; Terumo Corporation.