Leonardini Anna, D'Oria Rossella, Incalza Maria Angela, Caccioppoli Cristina, Andrulli Buccheri Valentina, Cignarelli Angelo, Paparella Domenico, Margari Vito, Natalicchio Annalisa, Perrini Sebastio, Giorgino Francesco, Laviola Luigi
Department of Emergency and Organ Transplantation, Section of Internal Medicine, Endocrinology, Andrology, and Metabolic Diseases, University of Bari Aldo Moro, I-70124 Bari, Italy.
Department of Emergency and Organ Transplantation, Section of Cardiac Surgery, University of Bari Aldo Moro, I-70124 Bari, Italy.
J Clin Endocrinol Metab. 2017 Nov 1;102(11):4136-4147. doi: 10.1210/jc.2017-00970.
Increased apoptosis of cardiomyocytes and cardiac progenitor cells (CPCs) in response to saturated fatty acids (SFAs) can lead to myocardial damage and dysfunction. Ceramides mediate lipotoxicity-induced apoptosis. Glucagonlike peptide-1 receptor (GLP1R) agonists exert beneficial effects on cardiac cells in experimental models.
To investigate the protective effects of GLP1R activation on SFA-mediated apoptotic death of human CPCs.
Human CPCs were isolated from cardiac appendages of nondiabetic donors and then exposed to palmitate with or without pretreatment with the GLP1R agonist exendin-4. Ceramide accumulation was evaluated by immunofluorescence. Expression of key enzymes in de novo ceramide biosynthesis was studied by quantitative reverse-transcription polymerase chain reaction and immunoblotting. Apoptosis was evaluated by measuring release of oligonucleosomes, caspase-3 cleavage, caspase activity, and terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling.
Exposure of the CPCs to palmitate resulted in 2.3- and 1.9-fold higher expression of ceramide synthase 5 (CERS5) and ceramide desaturase-1, respectively (P < 0.05). This was associated with intracellular accumulation of ceramide and activation of c-Jun NH2-terminal protein kinase (JNK) signaling and apoptosis (P < 0.05). Both coincubation with fumonisin B1, a specific ceramide synthase inhibitor, and CERS5 knockdown prevented ceramide accumulation, JNK activation, and apoptosis in response to palmitate (P < 0.05). Exendin-4 also prevented the activation of the ceramide biosynthesis and JNK in response to palmitate, inhibiting apoptosis (P < 0.05).
Excess palmitate results in activation of ceramide biosynthesis, JNK signaling, and apoptosis in human CPCs. GLP1R activation counteracts this lipotoxic damage via inhibition of ceramide generation, and this may represent a cardioprotective mechanism.
心肌细胞和心脏祖细胞（CPCs）对饱和脂肪酸（SFAs）反应性凋亡增加可导致心肌损伤和功能障碍。神经酰胺介导脂毒性诱导的凋亡。胰高血糖素样肽-1受体（GLP1R）激动剂在实验模型中对心脏细胞发挥有益作用。
研究GLP1R激活对SFA介导的人CPCs凋亡性死亡的保护作用。
从非糖尿病供体的心脏附属物中分离出人CPCs，然后在有或没有用GLP1R激动剂艾塞那肽-4预处理的情况下使其暴露于棕榈酸酯。通过免疫荧光评估神经酰胺积累。通过定量逆转录聚合酶链反应和免疫印迹研究从头神经酰胺生物合成中关键酶 的表达。通过测量寡核小体释放、半胱天冬酶-3切割、半胱天冬酶活性和末端脱氧核苷酸转移酶介导的dUTP缺口末端标记来评估凋亡。
CPCs暴露于棕榈酸酯导致神经酰胺合酶5（CERS5）和神经酰胺去饱和酶-1的表达分别升高2.3倍和1.9倍（P<0.05）。这与神经酰胺的细胞内积累以及c-Jun氨基末端蛋白激酶（JNK）信号传导和凋亡的激活相关（P<0.05）。与特异性神经酰胺合酶抑制剂伏马菌素B1共同孵育以及CERS5基因敲低均能防止棕榈酸酯诱导的神经酰胺积累、JNK激活和凋亡（P<0.05）。艾塞那肽-4还能防止棕榈酸酯诱导的神经酰胺生物合成和JNK激活，抑制凋亡（P<0.05）。
过量棕榈酸酯导致人CPCs中神经酰胺生物合成、JNK信号传导和凋亡激活。GLP1R激活通过抑制神经酰胺生成来抵消这种脂毒性损伤，这可能代表一种心脏保护机制。
