Altered dynamics in the circadian oscillation of clock genes in serum-shocked NIH-3T3 cells by the treatment of GYY4137 or AOAA.

Background And Purpose: Several members of the core clock mechanism are equipped with a Per-Arnt-Sim (PAS) domain through which they can bind haem [Fe(II)]. Haem is a ligand for the orphan receptors REV-ERBα/β (NR1D1/2), which regulate circadian rhythm and metabolism. The ability to bind haem sensitises these clock components to the action of small molecule gases, including NO, CO and HS. Studies conducted with European hamsters revealed that during winter sleep, key clock genes stop oscillating. At the same time, HS, when administered at subtoxic concentrations, can induce a hypometabolic state in the cell. We suppose that core clock components, including the nuclear receptors REV-ERBs, neuronal PAS domain protein 2 (nPAS2) and PER2, can be HS targets. The general objective of this study was to investigate the effect of the HS system on the expression profile of the core clock genes in cells in vitro.

Experimental Approach: We analysed the expression of Per1, Per2, Per3, Bmal1, Cry1, Cry2, Nr1d1, Nfil-3 and Dbp messenger RNA (mRNA) in serum-shocked NIH-3T3 cells treated with a slow-releasing HS donor (GYY4137) or the cystathionine beta-synthase (CBS) inhibitor (AOAA) cultured under constant darkness and collected during 3 days in 3 h interval.

Key Results And Conclusions And Implications: We found that pharmacological CBS inhibition increased the general expression and dynamics of several clock genes. On the other hand, increased HS decreased Per2 expression. These data suggest that CBS can affect circadian clock and effect on clock-controlled transcription output.