Lack of TRPV1 aggravates obesity-associated hypertension through the disturbance of mitochondrial Ca2+ homeostasis in brown adipose tissue

The combination of obesity and hypertension is associated with high morbidity and mortality; however, the mechanism underlying obesity-induced hypertension remains unclear. In this study, we detected the possible effects of TRPV1, a previously identified antihypertensive calcium (Ca(2+)) channel in adipose tissue, on the occurrence of obesity and hypertension in mice lacking UCP1, a spontaneously genetically manipulated obesity model, by generating TRPV1 and UCP1 double knockout mice. In these mice, obesity and hypertension appeared earlier and were more severe than in mice with the knockout of UCP1 or TRPV1 alone. The knockout of TRPV1 in UCP1 knockout mice further reduced functional brown adipose tissue (BAT) generation; decreased resting oxygen consumption, heat production, and locomotor activities; and was accompanied by severe mitochondrial respiratory dysfunction in BAT. Mechanistically, TRPV1, UCP1, and LETM1 acted as a complex to maintain an appropriate mitochondrial Ca(2+) level, and TRPV1 knockout caused a compensatory increase in mitochondrial Ca(2+) uptake via LETM1 activation. However, the compensatory response was blocked in UCP1(−/−) mice, resulting in dramatically reduced mitochondrial Ca(2+) uptake and higher production of ATP and oxidative stress. This study provides in vivo evidence for the critical role of BAT mitochondrial Ca(2+) homeostasis in obesity-associated hypertension and indicates that the TRPV1/UCP1/LETM1 complex may be an alternative intervention target.