3D mitochondrial remodeling during postnatal heart development

Abstract

The heart is featured by high mitochondrial volume, by which continuous contractile activity can be maintained. However, it is unclear how mitochondrial structures are matured during postnatal development. Using FIB‐SEM, we thus sought to identify 3D mitochondrial structural characteristics in the heart of mice at postnatal (P) day 1, 7, 14, and 42, respectively. Here, matured mitochondria (P14‐42) were shown to have larger and more spherical structures and were highly connected with adjacent mitochondria as compared to early postnatal days (P1‐7). Nevertheless, the immature mitochondria appeared to have more intense interaction with other subcellular organelles including lipid droplets and sarcotubular structures (i.e., SR/T‐tubules). Thus, our study suggests that initial mitochondrial development can be augmented by crosstalk with adjacent mitochondria as well as other subcellular components and that it would be important for the further mitochondrial maturation process in the heart muscle.