Physical exercise can improve brain function and delay neurodegeneration; however, the initial signal from muscle to brain is unknown. Here we show that the lactate receptor (HCAR1) is highly enriched in pial fibroblast-like cells that line the vessels supplying blood to the brain, and in pericyte-like cells along intracerebral microvessels. Activation of HCAR1 enhances cerebral vascular endothelial growth factor A (VEGFA) and cerebral angiogenesis. High-intensity interval exercise (5 days weekly for 7 weeks), as well as L-lactate subcutaneous injection that leads to an increase in blood lactate levels similar to exercise, increases brain VEGFA protein and capillary density in wild-type mice, but not in knockout mice lacking HCAR1. In contrast, skeletal muscle shows no vascular HCAR1 expression and no HCAR1-dependent change in vascularization induced by exercise or lactate. Thus, we demonstrate that a substance released by exercising skeletal muscle induces supportive effects in brain through an identified receptor.
Myocardial infarction (MI) triggers a reparative response involving fibroblast proliferation and differentiation driving extracellular matrix modulation necessary to form a stabilizing scar. Recently, it was shown that a genetic variant of the base excision repair enzyme NEIL3 was associated with increased risk of MI in humans. Here, we report elevated myocardial NEIL3 expression in heart failure patients and marked myocardial upregulation of Neil3 after MI in mice, especially in a fibroblast-enriched cell fraction. Neil3 mice show increased mortality after MI caused by myocardial rupture. Genome-wide analysis of 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) reveals changes in the cardiac epigenome, including in genes related to the post-MI transcriptional response. Differentially methylated genes are enriched in pathways related to proliferation and myofibroblast differentiation. Accordingly, Neil3 ruptured hearts show increased proliferation of fibroblasts and myofibroblasts. We propose that NEIL3-dependent modulation of DNA methylation regulates cardiac fibroblast proliferation and thereby affects extracellular matrix modulation after MI.
Treatment options are limited in patients with chronic immune thrombocytopenic purpura (ITP) which has been unresponsive to corticosteroids and/or splenectomy. Mycophenolate mophetil (MMF) is effective in many autoimmune disorders including severe and refractory ITP through its targeting of T-cell and B-cell lymphocytes. We report on the efficacy of MMF (1.5-2 g/day) in 16 adults with severe steroid-resistant ITP. MMF was administered for at least 12 weeks (median 37 weeks, range 14-64 weeks). Patients comprised of 10 females and six males, with median pre-treatment platelet counts of 8 × 10(9)/L, median age of 55 years, median ITP duration of 58 months and a median of four prior treatments (range 3-8); nine had been previously splenectomized. Eleven patients (69%) responded after 12 weeks of MMF: 6 (55%) achieving complete remission (CR) and five (45%) achieved partial remission (PR). MMF therapeutic responses were better in those patients who had had fewer prior treatments (p<0.05), and were independent of patient age, sex, disease duration, and splenectomy status (p>0.05). Five of the 11 responders (45%; 3CR/2PR) had sustained remissions; however, six responders (55%; 3CR/3PR) relapsed after median of 14 weeks (range 9-20). Three of the six relapsing patients responded to MMF reinstitution achieving stabile PRs; three were left untreated as none had further bleeding and their platelets remained at "safe" levels (median 30 × 10(9)/L). The MMF treatment was well tolerated; one heavily pretreated patient developed a bronchopneumonia and a second had an episode of diarrhea. MMF used as a second-line agent can produce a sustained response in severe ITP which has been unresponsive to steroid and/or splenectomy without major toxicity.
Mutations in the HECT, UBA and WWE domain-containing 1 (HUWE1) E3 ubiquitin ligase cause neurodevelopmental disorder X-linked intellectual disability (XLID). HUWE1 regulates essential processes such as genome integrity maintenance. Alterations in the genome integrity and accumulation of mutations have been tightly associated with the onset of neurodevelopmental disorders. Though HUWE1 mutations are clearly implicated in XLID and HUWE1 regulatory functions well explored, currently much is unknown about the molecular basis of HUWE1-promoted XLID. Here we showed that the HUWE1 expression is altered and mutation frequency increased in three different XLID individual (HUWE1 p.R2981H, p.R4187C and HUWE1 duplication) cell lines. The effect was most prominent in HUWE1 p.R4187C XLID cells and was accompanied with decreased DNA repair capacity and hypersensitivity to oxidative stress. Analysis of HUWE1 substrates revealed XLID-specific down-regulation of oxidative stress response DNA polymerase (Pol) λ caused by hyperactive HUWE1 p.R4187C. The subsequent restoration of Polλ levels counteracted the oxidative hypersensitivity. The observed alterations in the genome integrity maintenance may be particularly relevant in the cortical progenitor zones of human brain, as suggested by HUWE1 immunofluorescence analysis of cerebral organoids. These results provide evidence that impairments of the fundamental cellular processes, like genome integrity maintenance, characterize HUWE1-promoted XLID.
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