UCP1 and obesity due to melanocortin 4 receptor deficiency: Adipocyte-selective expression of light-gated channelrhodopsin-2 (ChR2) has been employed to trigger Ca2+ influx into adipocytes via optogenetics, which was sufficient to protect mice from diet-induced obesity, even in the presence of intact Ucp1. 97Interestingly, triggering Ca2+ influx was sufficient to enhance beige adipocyte respiration.97