Prolyl hydroxylase domain 2 reduction enhances skeletal muscle tissue regeneration after soft tissue trauma in mice

Abstract

The transcription factor Hypoxia-inducible factor 1 (HIF-1) plays a pivotal role in tissue regeneration. HIF-1 is negatively controlled by O 2-dependent prolyl hydroxylases with a predominant role of prolyl hydroxylase 2 isoform (Phd2). Transgenic mice, hypomorphic for this isoform, accumulate more HIF-1 under normoxic conditions. Using these mice, we investigated the influence of Phd2 and HIF-1 on the regenerative capability of skeletal muscle tissue after myotrauma. Phd2-hypomorphic and wild type mice (on C57Bl/6 background) were grouped with regeneration times from 6 to 168 hours after closed mechanic muscle trauma to the hind limb. Tissue samples were analysed by immuno-staining and real-time PCR. Bone marrow derived macrophages of wild type and Phd2-hypomorphic mice were isolated and analysed via flow cytometry and quantitative real-time PCR. Phd2 reduction led to a higher regenerative capability due to enhanced activation of myogenic factors accompanied by induction of genes responsible for glucose and lactate metabolism in Phd2-hypomorphic mice. Macrophage infiltration into the trauma areas in hypomorphic mice started earlier and was more pronounced compared to wild type mice. Phd2-hypomorphic mice also showed higher numbers of macrophages in areas with sustained trauma 72 hours after myotrauma application. In conclusion, we postulate that the HIF-1 pathway is activated secondary to a Phd2 reduction which may lead to i) higher activation of myogenic factors, ii) increased number of positive stem cell proliferation markers, and iii) accelerated macrophage recruitment to areas of trauma, resulting in faster muscle tissue regeneration after myotrauma. With the current development of prolyl hydroxylase domain inhibitors, our findings point towards a potential clinical benefit after myotrauma.

PHD3 mediates denervation skeletal muscle atrophy through Nf‐κB signal pathway

“…For instance, previous studies have shown that PHD2 can regulate skeletal muscle fiber type transition and inhibit skeletal muscle regeneration through the calcineurin / NFATc1-dependent pathway. [33][34][35] In addition, mice with the interference of PHD1 or PHD3 activity also had a protective effect on hind limb ischemia and reduced muscle mass loss after ischemic injury. 36,67 Similarly, salidroside, a drug inhibitor, inhibited PHD3, and restored the proliferation and angiogenic factor secretion potential of skeletal muscle cells inhibited by hyperglycemia.…”

Dapagliflozin Promotes Neovascularization by Improving Paracrine Function of Skeletal Muscle Cells in Diabetic Hindlimb Ischemia Mice Through PHD2/HIF-1α Axis

“…PHD2 suppression in skeletal muscle cells has been shown to enhance HIF-1α accumulation and angiogenic factors’ expression ( Wu et al., 2015 ; Settelmeier et al., 2020 ). As the downstream factors of HIF-1α, VEGF-A and PDGF-BB could exert an autocrine signaling to stimulate skeletal muscle cells’ proliferation and migration potentials ( Webb and Lee, 1997 ; Germani et al., 2003 ).…”

Hypoxia and Hypoxia-Inducible Factor Signaling in Muscular Dystrophies: Cause and Consequences

“…A recent study in vivo showed that Phd2-deficency and the subsequent Hif-1α accumulation in mice enhanced and accelerated skeletal muscle regeneration after a myotrauma [100]. In this model, the authors also described an accelerated macrophage recruitment to the injured area [100]. Myotrauma was also reported to induce a hypoxic microenvironment leading to Hif-1α accumulation in myofibers and myeloid cells.…”

“…In normoxic conditions, Hif-1α can be detected in skeletal muscle but its protein level is dependent on the muscle fiber type [104]. A recent study in vivo showed that Phd2deficency and the subsequent Hif-1α accumulation in mice enhanced and accelerated skeletal muscle regeneration after a myotrauma [100]. In this model, the authors also described an accelerated macrophage recruitment to the injured area [100].…”

“…The satellite stem cell subpopulation (PAX7+ and MYF5−) can proceed to self-renewal to replenish the SC pool.HIF-1α pathway activation was found critical to maintain SC quiescence[99]. It was associated to an enhanced myogenic factor activation, an increased number of PAX7+ cells, a more rapid macrophage recruitment after a myotrauma[100] and could promote myogenesis by increasing Myod expression through the WNT pathway[101].…”