Temporal analysis of skeletal muscle remodelling post hindlimb ischemia reveals intricate autophagy regulation

Hind Limb Ischemia (HLI) is the most severe form of peripheral arterial disease, associated with a substantial reduction of limb blood flow that impairs skeletal muscle homeostasis to promote functional disability. The molecular regulators of HLI-induced muscle perturbations remain poorly defined. This study investigated whether perturbations in the molecular catabolic-autophagy signalling network were linked to temporal remodelling of skeletal muscle in HLI. HLI was induced via hindlimb ischemia (femoral artery ligation) and confirmed by Doppler echocardiography. Experiments were terminated at time points defined as early- (7 days; n=5) or late (28 days; n=5) stage HLI. Ischemic and non-ischemic (contralateral) limb muscles were compared. Ischemic vs. non-ischemic muscles demonstrated overt remodelling at early-HLI but normalised at late-HLI. Early-onset fibre atrophy was associated with excessive autophagy signalling in ischemic muscle: protein expression increased for Beclin-1, LC3 and p62 (p<0.05) but proteasome-dependent markers were reduced (p<0.05). Mitophagy signalling increased in early-stage HLI which aligned with an early and sustained loss of mitochondrial content (p<0.05). Upstream autophagy regulators Sestrins showed divergent responses during early-stage HLI (Sestrin2 increased while Sestrin1 decreased; p<0.05) in parallel to increased AMPK phosphorylation (p