Biology subjects

Jakubowski, H.

Publications and source records attributed to Jakubowski, H..

3 recordsLinked to original sources

bioRxiv2023

Homocysteine Metabolites Inhibit Autophagy and Elevate Amyloid Beta by Impairing Phf8/H4K20me1-dependent Epigenetic Regulation of mTOR in Cystathionine Beta-Synthase-Deficient Mice

The loss of cystathionine {beta}-synthase (CBS), an important homocysteine (Hcy)-metabolizing enzyme or the loss of PHF8, an important histone demethylase participating in epigenetic regulation, causes severe mental retardation in humans. Similar neuropathies were also observed in Cbs-/- and Phf8-/- mice. How CBS or PHF8 depletion can cause neuropathy was unknown. To answer this question, we examined a possible interaction between PHF8 and CBS using Cbs-/- mouse and neuroblastoma cell models. We quantified gene expression by RT-qPCR and Western blotting, mTOR-bound H4K20me1 by chromatin immunoprecipitation (CHIP) assay, and amyloid {beta} (A{beta}) by confocal fluorescence microscopy using anti-A{beta} antibody. We found significantly reduced expression of Phf8, increased H4K20me1, increased mTOR expression and phosphorylation, and increased App, both on protein and mRNA levels in brains of Cbs-/- mice vs. Cbs+/- sibling controls. Autophagy-related proteins Becn1, Atg5, and Atg7 were downregulated while p62 was upregulated on protein and mRNA levels, suggesting impaired autophagy in Cbs-/- brains. In mouse neuroblastoma N2a or N2a-APPswe cells, treatments with Hcy-thiolactone, N-Hcy-protein or Hcy, or Cbs gene silencing by RNA interference significantly reduced Phf8 expression and increased total H4K20me1 as well as mTOR promoter-bound H4K20me1. This led to transcriptional mTOR upregulation, autophagy downregulation, and significantly increased App and A{beta} levels. The Phf8 gene silencing increased A{beta}, but not App, levels. Taken together, our findings identify Phf8 as a regulator of A{beta} synthesis and suggest that neuropathy of Cbs deficiency is mediated by Hcy metabolites, which transcriptionally dysregulate the Phf8->H4K20me1->mTOR->autophagy pathway thereby increasing A{beta} accumulation.

biochemistry↗

bioRxiv2023

Depletion of bleomycin hydrolase (Blmh) downregulates histone demethylase Phf8, impairs mTOR signaling/autophagy, accelerates amyloid beta accumulation, and induces neurological deficits in mice

Bleomycin hydrolase (BLMH), a homocysteine (Hcy)-thiolactone detoxifying enzyme, is attenuated in brains of Alzheimers disease patients. In mice, Blmh depletion causes astrogliosis and behavioral changes. Depletion of histone demethylase PHF8, which controls mTOR signaling by demethylating H4K20me1, causes neuropathy in humans and mice. Here we examined how Blmh depletion affects the Phf8/H4K20me1/mTOR signaling/autophagy pathway and amyloid beta (A{beta}) accumulation and cognitive/neuromotor performance in mice. We found that Phf8 was significantly downregulated in brains of Blmh-/- mice vs. Blmh+/+ sibling controls. H4K20me1, mTOR, phospho-mTOR, and App were upregulated while autophagy markers Bcln1, Atg5, and Atg7 were downregulated in Blmh-/- brains. Blmh depletion caused similar biochemical changes and significantly elevated A{beta} in Blmh-/-5xFAD vs. Blmh+/+5xFAD brains. Behavioral testing identified cognitive/neuromotor deficits in Blmh-/- and Blmh-/-5xFAD mice. In Blmh-depleted N2a-APPswe cells, Phf8 was downregulated, while APP, total H4K20me1, and H4K20me1-mTOR promoter binding were elevated. This led to mTOR upregulation, autophagy downregulation, and significantly increased APP and A{beta} levels. Phf8 depletion or treatments with Hcy-thiolactone or N-Hcy-protein, metabolites that are elevated in Blmh-depleted mice, induced similar biochemical changes in N2a-APPswe cells, akin to those in induced by Blmh depletion. Taken together, our findings indicate that Blmh interacts with APP and the Phf8/H4K20me1/mTOR/autophagy pathway and show that disruption of these interactions lead to A{beta} accumulation and cognitive and neuromotor deficits.

biochemistry↗

bioRxiv2022

Cystathionine β-synthase gene inactivation dysregulates major urinary protein biogenesis and impairs sexual signaling in mice

Reproductive success in mice depends on major urinary proteins (Mup) that facilitate sexual interactions between females and males. Deletion of cystathionine {beta}-synthase (Cbs) gene, a metabolic gene important for homeostasis of one-carbon metabolism, impairs reproduction by causing female infertility in mice. Here we examined Mup biogenesis and sexual signaling in Cbs-/- vs. Cbs+/- mice. We found that total urinary Mup protein was significantly reduced in male and female Cbs-/- vs. Cbs+/- mice. SDS-PAGE/Western blot, ESIMS, and RT-qPCR analyses of the liver, plasma, and urinary proteins identified a male-specific Mup20 in Cbs-/-, but not Cbs+/- females. As other Mups were significantly reduced, the 18,893 Da Mup20 became the most abundand in urine of Cbs-/- females and males. Effects of Cbs genotype on 18,645 Da, 18,693 Da, and 18,709 Da Mup species abundance were Mup and sex-specific. Cbs-dependent changes in hepatic Mups and Mup20 expression were similar at the protein and mRNA level. Changes in Mups, but not in Mup20, can be explained by downregulation of hepatic Zhx2 and Ghr receptors in Cbs-/- mice. Behavioral testing showed that Cbs+/- females were attracted to Cbs+/- but not to Cbs-/- male urine. Cbs+/- males did not countermark urine of Cbs-/- males but countermarked urine of other Cbs+/- males and were attracted to urines of Cbs-/- as well as Cbs+/- females. Cbs-/- males did not countermark urine of Cbs+/- males but were still attracted to urines of Cbs+/- females. Taken together, these findings show that Cbs, a metabolic gene, plays an important role in the regulation of Mup biogenesis and sexual signaling in mice.

animal behavior and cognition↗