Abstract
(1) The beneficial effects of hydrogen sulfide (H2S) on the cardiovascular and nervous system have recently been re-evaluated. It has been shown that lanthionine, a side product of H2S biosynthesis, previously used as a marker for H2S production, is dramatically increased in circulation in uremia, while H2S release is impaired. Thus, lanthionine could be classified as a novel uremic toxin. Our research was aimed at defining the mechanism(s) for lanthionine toxicity. (2) The effect of lanthionine on H2S release was tested by a novel lead acetate strip test (LAST) in EA.hy926 cell cultures. Effects of glutathione, as a redox agent, were assayed. Levels of sulfane sulfur were evaluated using the SSP4 probe and flow cytometry. Protein content and glutathionylation were analyzed by Western Blotting and immunoprecipitation, respectively. Gene expression and miRNA levels were assessed by qPCR. (3) We demonstrated that, in endothelial cells, lanthionine hampers H2S release; reduces protein content and glutathionylation of transsulfuration enzyme cystathionine-β-synthase; modifies the expression of miR-200c and miR-423; lowers expression of vascular endothelial growth factor VEGF; increases Ca2+ levels. (4) Lanthionine-induced alterations in cell cultures, which involve both sulfur amino acid metabolism and calcium homeostasis, are consistent with uremic dysfunctional characteristics and further support the uremic toxin role of this amino acid.
Highlights
Lanthionine is a non-protein amino acid generated as a side-product of trassulfuration, a two-step metabolic pathway catalyzed by cystathionine-β-synthase (CBS) and cystathionine-γ-lyase (CSE)
In order to measure the effects of lanthionine on the release of H2S, as well as on sulfane sulfur content, endothelial EA.hy926 cells were treated with lanthionine, at concentrations comparable with those detected in vivo in uremia [6]
It appears that the kinetics of the recovery of gaseous H2S release and sulfane sulfur increase are quite different upon the addition of both GSH and lanthionine, or GSH alone in the medium, compared to lanthionine treatment
Summary
Lanthionine is a non-protein amino acid generated as a side-product of trassulfuration, a two-step metabolic pathway catalyzed by cystathionine-β-synthase (CBS) and cystathionine-γ-lyase (CSE). Transsulfuration is a bifunctional pathway; in the complete classical mode, the two enzymes act in sequence, where CBS catalyzes the condensation of serine and homocysteine to form cystathionine; this in turn is hydrolyzed by CSE to α-ketobutyrate and cysteine [1,2]. It has been demonstrated that this amino acid accumulates in circulation in uremia and may inhibit transsulfuration enzymes in cell cultures, possibly contributing to the hyperhomocysteinemia almost constantly associated with uremia [6]. The uremic toxin characteristic of lanthionine has been further assessed in a zebrafish animal model, where it was demonstrated that lanthionine determines significant alterations of larval cardiovascular development, together with behavioral modifications; these alterations are partly reversible upon glutathione treatment [7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
