Sulphide signalling potentiates apoptosis through the up-regulation of IP3 receptor types 1 and 2

To investigate an interaction between the calcium and sulphide signalling pathways, particularly effects of the slow H2 S release donor morpholin-4-ium-4-methoxyphenyl-(morpholino)-phosphinodithioate (GYY4137) on the expression of inositol 1,4,5-trisphosphate receptors (IP3 R) with the possible impact on the apoptosis induction in HeLa cells.

Gene expression, Western blot analysis, apoptosis determination by Annexin-V-FLUOS and drop in mitochondrial membrane potential by 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolyl-carbocyanine iodide (JC1) and immunofluorescence were used to determine differences in control and GYY4137-treated HeLa cells.

In HeLa cell line, GYY4137 (10 μm) up-regulated expression of the IP3 R1 and IP3 R2, but not IP3 R3 on both mRNA and protein levels. Concurrently, cytosolic calcium increased and reticular calcium was depleted in concentration-dependent manner, partially by the involvement of IP3 R. Depletion of calcium from reticulum was accompanied by increase in endoplasmic reticulum (ER) stress markers, such as X-box, CHOP and ATF4, thus pointing to the development of ER stress due to GYY4137 treatment. Also, GYY4137 treatment of HeLa cells increased the number of apoptotic cells.

These results suggest an involvement of H2 S in both IP3 -induced calcium signalling and induction of apoptosis, possibly through the activation of ER stress.