A role for the cystathionine-β-synthase /H2S axis in astrocyte dysfunction in the aging brain

Astrocytic dysfunction is central to age-related neurodegenerative diseases. However, the mechanisms leading to astrocytic dysfunction are not well understood. We identify that among the diverse cellular constituents of the brain, murine and human astrocytes are enriched in the expression of CBS. Depleting CBS in astrocytes causes mitochondrial dysfunction, increases the production of reactive oxygen species (ROS) and decreases cellular bioenergetics that can be partially rescued by exogenous H2S supplementation or by re-expressing CBS. Conversely, the CBS/H2S axis, associated protein persulfidation and proliferation are decreased in astrocytes upon oxidative stress which can be rescued by exogenous H2S supplementation. Here we reveal that in the aging brain, the CBS/H2S axis is downregulated leading to decreased protein persulfidation, together augmenting oxidative stress. Our findings uncover an important protective role of the CBS/H2S axis in astrocytes that may be disrupted in the aged brain.

Proteomics Profiling of S-sulfurated Proteins in Acinetobacter baumannii

Hydrogen sulfide (H₂S) is emerging as an important modulator in bacterial cytoprotection against the host immune response in infected animals, which may well be attributed to downstream highly oxidized sulfur species, termed reactive sulfur species (RSS), derived from H₂S. One mechanism by which H₂S/RSS may signal in the cell is through proteome S-sulfuration (persulfidation), which is the conversion of protein thiols (-SH) to protein persulfides (-SSH). While several analytical methods have been developed to profile sites of protein persulfidation, few have been applied to bacterial cells. The analytical workflow presented here was recently utilized to profile proteome persulfidation in the major human pathogen Acinetobacter baumannii treated with an exogenous sulfide source, Na₂S. The data obtained using this protocol allow quantitation of the change in persulfidation status of each cysteine in the proteome normalized to the change in protein abundance, thus identifying sites of persulfidation that may constitute regulatory modifications. These can be validated using follow-up biochemical studies.

The multifaceted roles of sulfane sulfur species in cancer-associated processes

Sulfane sulfur species comprise a variety of biologically relevant hydrogen sulfide (H₂S)-derived species, including per- and poly-sulfidated low molecular weight compounds and proteins. A growing body of evidence suggests that H₂S, currently recognized as a key signaling molecule in human physiology and pathophysiology, plays an important role in cancer biology by modulating cell bioenergetics and contributing to metabolic reprogramming. This is accomplished through functional modulation of target proteins via H₂S binding to heme iron centers or H₂S-mediated reversible per- or poly-sulfidation of specific cysteine residues. Since sulfane sulfur species are increasingly viewed not only as a major source of H₂S but also as key mediators of some of the biological effects commonly attributed to H₂S, the multifaceted role of these species in cancer biology is reviewed here with reference to H₂S, focusing on their metabolism, signaling function, impact on cell bioenergetics and anti-tumoral properties.