Communication between the endoplasmic reticulum (ER) and mitochondria plays a pivotal role in Ca2+ signaling, energy metabolism, and cell survival. Dysfunction in this cross-talk leads to metabolic and neurodegenerative diseases. Wolfram syndrome is a fatal neurodegenerative disease caused by mutations in the ER-resident protein WFS1. Here, we showed that WFS1 formed a complex with neuronal calcium sensor 1 (NCS1) and inositol 1,4,5-trisphosphate receptor (IP3R) to promote Ca2+ transfer between the ER and mitochondria. In addition, we found that NCS1 abundance was reduced in WFS1-null patient fibroblasts, which showed reduced ER-mitochondria interactions and Ca2+ exchange. Moreover, in WFS1-deficient cells, NCS1 overexpression not only restored ER-mitochondria interactions and Ca2+ transfer but also rescued mitochondrial dysfunction. Our results describe a key role of NCS1 in ER-mitochondria cross-talk, uncover a pathogenic mechanism for Wolfram syndrome, and potentially reveal insights into the pathogenesis of other neurodegenerative diseases.

Aims: Heme oxygenase-1 (HO-1) is a cytoprotective enzyme that can be down-regulated in diabetes. Its importance for mature endothelium has been described, but its role in proangiogenic progenitors is not well known. We investigated the effect of HO-1 on the angiogenic potential of bone marrow-derived cells (BMDCs) and on blood flow recovery in ischemic muscle of diabetic mice. BMDCs revealed the attenuated up-regulation of proangiogenic genes in response to hypoxia. Heterozygous HO-1 +/ -diabetic mice subjected to hind limb ischemia exhibited reduced local expression of vascular endothelial growth factor (VEGF), placental growth factor (PlGF), stromal cell-derived factor 1 (SDF-1), VEGFR-1, VEGFR-2, and CXCR-4. This was accompanied by impaired revascularization of ischemic muscle, despite a strong mobilization of bone marrow-derived proangiogenic progenitors (Sca-1 + CXCR-4 + ) into peripheral blood. Blood flow recovery could be rescued by local injections of conditioned media harvested from BMDCs, but not by an injection of cultured BMDCs. Innovation: This is the first report showing that HO-1 haploinsufficiency impairs tissue revascularization in diabetes and that proangiogenic in situ response, not progenitor cell mobilization, is important for blood flow recovery. Conclusions: HO-1 is necessary for a proper proangiogenic function of BMDCs. A low level of HO-1 in hyperglycemic mice decreases restoration of perfusion in ischemic muscle, which can be rescued by a local injection of conditioned media from cultured

AimsHaem oxygenase-1 (HO-1) is a haem-degrading enzyme that generates carbon monoxide, bilirubin, and iron ions. Through these compounds, HO-1 mitigates cellular injury by exerting antioxidant, anti-apoptotic, and anti-inflammatory effects. Here, we examined the influence of HO-1 deficiency and transient hypoxia/ischaemia-induced HO-1 overexpression on post-injury hindlimb recovery.Methods and resultsMice lacking functional HO-1 (HO-1−/−) showed reduced reparative neovascularization in ischaemic skeletal muscles, impaired blood flow (BF) recovery, and increased muscle cell death compared with their wild-type littermates. Human microvascular endothelial cells (HMEC-1) transfected with plasmid vector (pHRE-HO-1) carrying human HO-1 driven by three hypoxia response elements (HREs) and cultured in 0.5% oxygen demonstrated markedly increased expression of HO-1. Such upregulated HO-1 levels were effective in conferring protection against H2O2-induced cell death and in promoting the proangiogenic phenotype of HMEC-1 cells. More importantly, when delivered in vivo, pHRE-HO-1 significantly improved the post-ischaemic foot BF in mice subjected to femoral artery ligation. These effects were associated with reduced levels of pro-inflammatory cytokines (IL-6 and CXCL1) and lower numbers of transferase-mediated dUTP nick-end labelling-positive cells. Moreover, HO-1 delivered into mouse skeletal muscles seems to influence the regenerative potential of myocytes as it significantly changed the expression of transcriptional (Pax7, MyoD, myogenin) and post-transcriptional (miR-146a, miR-206) regulators of skeletal muscle regeneration.ConclusionOur results suggest the therapeutic potential of HO-1 for prevention of adverse effects in critical limb ischaemia.