Organelles articles from across Nature Portfolio

We show that the mitochondrial fission proteins MiD49 and MiD51 are activated by fatty acyl-coenzyme A (FA-CoA). FA-CoA binds in a previously identified pocket located within MiDs, inducing their oligomerization and ability to activate the dynamin DRP1, ultimately promoting mitochondrial fission. Activated MiDs synergize with mitochondrial fission factor (MFF) in stimulating DRP1 activity, leading us to hypothesize that MiDs act upstream of MFF during mitochondrial fission.

Mitochondrial fission, performed by Drp1, is carefully regulated, particularly in neurons. Here, the authors examine Drosophila Cdk8/CDK19 function in mitochondrial fission and uncover a role phosphorylating Drp1 in the cytoplasm and show overexpression suppresses a Parkinson’s disease model.

Import of proteins into peroxisomes depends on PEX5, PEX13 and PEX14. Here the authors obtain crystal structures and NMR data to show the recognition of diaromatic peptide motifs on a noncanonical surface of the PEX13 SH3 domain, revealing a dynamic network which modulates peroxisomal matrix import.

The spatial mapping of proteins can give important functional insights. Here, Zhu et al. develop a cross-linking mass spectrometry-based spatial proteomics method that does not require protein engineering, affords sub-organelle resolution, and elucidates both protein locations and membrane topologies.

We show that the mitochondrial fission proteins MiD49 and MiD51 are activated by fatty acyl-coenzyme A (FA-CoA). FA-CoA binds in a previously identified pocket located within MiDs, inducing their oligomerization and ability to activate the dynamin DRP1, ultimately promoting mitochondrial fission. Activated MiDs synergize with mitochondrial fission factor (MFF) in stimulating DRP1 activity, leading us to hypothesize that MiDs act upstream of MFF during mitochondrial fission.

Cellular and organismal aging have been consistently associated with mitochondrial dysfunction and inflammation. Accumulating evidence indicates that aging-related inflammatory responses are mechanistically linked to compromised mitochondrial integrity coupled with mtDNA-driven CGAS activation, a process that is tonically inhibited by mitophagy.

AMPK directly phosphorylates the mitochondrial protein SYNJ2BP to facilitate its interaction with the RNA-binding protein SYNJ2a, which transports Pink1 mRNA into neurites. AMPK inhibition downstream of insulin signalling untethers Pink1 mRNA from neuronal mitochondria and favours PINK1-dependent mitophagy in neurons. ApoE4-induced insulin receptor internalization reverses the process by stabilizing Pink1 mRNA binding to neuronal mitochondria.

The endoplasmic reticulum (ER) controls the synthesis of lipids and proteins and Ca²⁺ homeostasis, as well as contacting other organelles and the plasma membrane. A study now looks at a process by which this compartment is remodelled in axons during neurogenesis: the lysosomal clearance of ER subdomains, driven by FAM134 and CCPG1 proteins.

In this issue of Nature Metabolism, it is shown that the abundance of Caenorhabditis elegans branched-chain aminotransferase-1 (BCAT-1) — which catalyses the first step of branched-chain amino acid (BCAA) catabolism — declines sharply in aged wild-type nematodes but not in slowly ageing mutants, and that stimulating BCAA catabolism extends reproductive longevity.

The prevailing notion that mitochondrial diseases arise from ATP deficiency is challenged by recent evidence that oxidative phosphorylation defects trigger maladaptive stress responses consuming excess energy. We argue that this chronic state of hypermetabolism imposes energetic constraints, thus causing mitochondrial disease pathophysiology, calling for careful translational studies from organelle to organism.