Mitochondria-targeted hydrogen sulfide attenuates endothelial senescence by selective induction of splicing factors HNRNPD and SRSF2.

Cellular senescence is a key driver of ageing, influenced by age-related changes to the regulation of alternative splicing. Hydrogen sulfide (H2S) has similarly been described to influence senescence, but the pathways by which it accomplishes this are unclear.We assessed the effects of the slow release H2S donor Na-GYY4137 (100 µg/ml), and three novel mitochondria-targeted H2S donors AP39, AP123 and RT01 (10 ng/ml) on splicing factor expression, cell proliferation, apoptosis, DNA replication, DNA damage, telomere length and senescence-related secretory complex (SASP) expression in senescent primary human endothelial cells.All H2S donors produced up to a 50% drop in senescent cell load assessed at the biochemical and molecular level. Some changes were noted in the composition of senescence-related secretory complex (SASP); IL8 levels increased by 24% but proliferation was not re-established in the culture as a whole. Telomere length, apoptotic index and the extent of DNA damage were unaffected. Differential effects on splicing factor expression were observed depending on the intracellular targeting of the H2S donors. Na-GYY4137 produced a general 1.9 - 3.2-fold upregulation of splicing factor expression, whereas the mitochondria-targeted donors produced a specific 2.5 and 3.1-fold upregulation of SRSF2 and HNRNPD splicing factors only. Knockdown of SRSF2 or HNRNPD genes in treated cells rendered the cells non-responsive to H2S, and increased levels of senescence by up to 25% in untreated cells.Our data suggest that SRSF2 and HNRNPD may be implicated in endothelial cell senescence, and can be targeted by exogenous H2S. These molecules may have potential as moderators of splicing factor expression and senescence phenotypes.