Cysteine metabolism and hydrogen sulfide signaling in Huntington's disease.

The semi-essential amino acid, cysteine, plays important roles in both essential cellular processes as well as in modulation of signaling cascades. Cysteine is obtained both from the diet as well as generated endogenously via the transsulfuration pathway. Cysteine is further utilized in protein synthesis and biosynthesis of various sulfur containing molecules. One of the products of cysteine catabolism, hydrogen sulfide (H2S), is a gaseous signaling molecule, which regulates a multitude of cellular processes. Cysteine metabolism is dysregulated in several neurodegenerative diseases and during aging. This minireview focuses on aberrant cysteine and H2S metabolism in Huntington's disease, a neurodegenerative disease caused by expansion of polyglutamine encoding repeats in the gene huntingtin, which leads to motor and cognitive deficits.