Hydrogen sulfide regulates cAMP homeostasis and renin degranulation in As4.1 and rat renin-rich kidney cells

Lu M, Liu YH, Ho CY, Tiong CX, Bian JS. Hydrogen sulfide regulates cAMP homeostasis and renin degranulation in As4.1 and rat renin-rich kidney cells. Am J Physiol Cell Physiol 302: C59-C66, 2012. First published September 21, 2011; doi:10.1152/ajpcell.00341.2010.-The present study aims to investigate the regulatory effect of hydrogen sulfide (H2S) on cAMP homeostasis and renin degranulation in As4.1 and rat renin-rich kidney cells. It was found in the present study that NaHS at 0.1-10 mu M significantly decreased cAMP production in As4.1 cells treated with isoproterenol (a beta-adrenoceptor agonist), forskolin (an adenylyl cyclase activator), or 3-isobutyl-1-methylxanthine (IBMX, a phosphodiesterase inhibitor). NaHS at 10 mu M suppressed adenylate cyclase activity but stimulated phosphodiesterase activity. We continued to study whether H2S may mediate cAMP-dependent renin degranulaion in As4.1 cells. It was found that NaHS at 0.1-10 mu M significantly increased intracellular renin protein level. Moreover, NaHS reversed the declined renin content within As4.1 cells and normalized the upregulated renin activity in the culture medium of As4.1 cells treated with the above three stimuli. RT-PCR showed that cystathionine-gamma-lyase is the main enzyme to produce endogenous H2S in As4.1 cells. Overexpression of cystathionine-gamma-lyase increased endogenous H2S production and suppressed isoproterenol-induced renin release, suggesting that endogenous H2S may also inhibit renin release from As4.1 cells. We also tested whether H2S has a similar effect in renin-rich kidney cells. It was found that isoproterenol elevated intracellular cAMP level and extracellular renin activity but decreased renin protein level in the renin-rich kidney cells. Pretreatment with NaHS abolished these effects. In conclusion, H2S regulates cAMP homeostasis via inhibition of adenylate cyclase and stimulation of phosphodiesterase. Our findings suggest that H2S plays a critical role in regulation of renin degranulation in As4.1 and rat renin-rich kidney cells.