Fig. 4.

CaMKK mediates LS-induced expression of KCa3.1 and KCa2.3 via activation of Akt and histone acetyltransferase p300. A and B: HCAECs were exposed to LS for 24 h in the absence or presence of KG-501 (an inhibitor of p300 binding to transcription factors, such as CREB, via KIX:KID domains interaction) (4). KG-501 inhibited LS-induced upregulation of KCa3.1 (A) and KCa2.3 (B) mRNA expression, whereas it lowered KCa2.3 but not KCa3.1 expression under ST condition. C: LS-induced increase in KCa2.3 and KCa3.1 protein expression levels was also suppressed by KG-501. Top: a representative image of immunoblots. Bottom: the summaries of densitometric analysis of KCa3.1 and KCa2.3 (n = 3). Electronically spliced and rearranged images are shown, as a white line indicates between the lanes, because responses to multiple inhibitors and a time course of shear stress were simultaneously examined in the original experiment. D: exposure to LS for 15 min induced phosphorylation of p300 (Ser1834) in HCAECs, which was abolished by CaMKK inhibition with STO-609 (top). In contrast, CREB phosphorylation was increased by STO-609 treatment under ST condition or after 30 min of LS. Electronically spliced and rearranged p-CREB and CREB images are shown due to a different arrangement in the original images. Akt inhibition with Akt inhibitor IV also dramatically abolished p300 phosphorylation induced by a 60 min of exposure to LS, whereas it had a modest inhibitory effect on phosphorylated CREB levels (bottom). *Signficant difference vs. ST (P < 0.05). #Signficant difference vs. LS (P < 0.05).