ATF5 and osteoporosis: However, under metabolic dysfunctions or stress, such as starvation, ATF5 accumulates in dysfunctional mitochondria and induces the replication of heteroplasmic mtDNA.[14] Recently, ATF5 is shown to mediate the replication of heteroplasmic mtDNA with m.3243A > G, attributing to mitochondrial dysfunctions and osteoporosis in patients.[15] In this study, we observed the ATF5 accumulation within mitochondria, which was associated with elevated UPRmt in oocytes of OB females.