The role of tyrosine kinases in capacitative calcium influx-mediated aldosterone production in bovine adrenal zona glomerulosa cells

Abstract

In adrenal glomerulosa cells, the stimulation of aldosterone biosynthesis by angiotensin II (Ang II) involves the activation of a capacitative Ca 2+ influx through calcium release-activated calcium (CRAC) channels. In various mammalian cell systems, it has been shown that CRAC channel activation and Ca 2+ entry require tyrosine kinase activity. We have therefore examined in this work whether similar mechanisms contribute to Ang II-induced mineralocorticoid biosynthesis. In fluo-3-loaded isolated bovine glomerulosa cells, two inhibitors of tyrosine kinases, genistein and methyl-2,5-dihydroxycinnamate (MDHC) (100 µM) prevented capacitative Ca 2+ entry elicited by Ang II (by 54 and 62% respectively), while the inhibitor of epidermal growth factor (EGF) receptor tyrosine kinase, lavendustin A, was without effect. Similar results were observed on Ca 2+ influx triggered by thapsigargin, an inhibitor of microsomal Ca 2+ pumps. The inhibitors blocked Ang II-stimulated pregnenolone and aldosterone production in the same rank order. In addition to its specific effect on capacitative Ca 2+ influx, genistein also affected the late steps of the steroidogenic pathway, as shown by experiments in which the rate-limiting step (intramitochondrial cholesterol transfer) was bypassed with 25-OH-cholesterol (25-OH-Chol), cytosolic calcium was clamped at stimulated levels or precursors of the late enzymatic steps were supplied. In contrast, genistin, a structural analogue of genistein devoid of tyrosine kinase inhibitory activity, was almost without effect on pregnenolone or 11-deoxycorticosterone (DOC) conversion to aldosterone. These results suggest that, in bovine adrenal glomerulosa cells, Ang II promotes capacitative Ca 2+ influx and aldosterone biosynthesis through tyrosine kinase activation.

Differential effects of intravenous anesthetics on capacitative calcium entry in human pulmonary artery smooth muscle cells

“…It has been reported that depletion of intracellular Ca 2ϩ stores triggers tyrosine phosphorylation (29), and inhibition of TK attenuates CCE in a number of cell types (2,32), including smooth muscle (8). We have demonstrated that inhibition of TK attenuates CCE in canine PASMCs and PVSMCs (18,30).…”

Acute and chronic regulation of aldosterone production

“…Indeed, this calcium influx is essential for a continued aldosterone secretory response (Barrett et al, 1989; Ganguly and Davis, 1994), as well as for regulating PKC activity (Kojima et al, 1994), since inhibition of calcium influx with calcium channel antagonists decreases AngII-induced aldosterone secretion (Kojima et al, 1985c; Rossier et al, 1996; Rossier et al, 1998; Spät and Hunyady, 2004). Calcium influx occurs through voltage-dependent T- and L-type calcium channels, as well as store-operated calcium channels or capacitative calcium influx (Aptel et al, 1999; Burnay et al, 1994; Burnay et al, 1998; Spät and Hunyady, 2004). The activity of these voltage-dependent channels is maintained by appropriate membrane polarization, maintained by proper functioning of potassium channels, such as TWIK-related acid-sensitive K (TASK) channels (Davies et al, 2008; Nogueira et al, 2010b).…”

Janus Kinase 2 and Calcium Are Required for Angiotensin II-dependent Activation of Steroidogenic Acute Regulatory Protein Transcription in H295R Human Adrenocortical Cells

“…Genistein treatment resulted in a concentration-dependent decrease in the Ang IIstimulated StAR promoter activity and progesterone production reaching a maximum inhibition of 60 -70%. 2 However, genistein has many effects within the cell, including inhibition of capacitative calcium influx in bovine adrenal cells (30). Therefore, we tested Src and JAK2 kinases using the more selective inhibitors PP2 and AG490, respectively.…”