Figure 6.

Summary of the proposed metabolic IP₃-mediated SR/mitochondrial signaling pathway in the presence (upper panel) or absence (lower panel) of intact Mfn2-tethers. IP₃-mediated mitochondrial Ca²⁺ uptake in WT myocytes (upper panel), which is followed by an increase in ATP generation. When the physical contact of mitochondria and the SR is disturbed by knockout of Mfn2 (lower panel), Ca²⁺ released from the SR by IP₃ cannot be taken up into mitochondria anymore leading to the decrease in ATP level. Yellow circles: Ca²⁺, yellow arrow: Ca²⁺ movement, green arrow: IP₃ movement.