科研之友
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摘要
Voltage-gated M-type (KCNQ) K+ channels play critical roles in regulation of neuronal excitability. Previous work showed A-kinase-anchoring protein (AKAP) 79/150-mediated protein kinase C (PKC) phosphorylation of M channels to be involved in M current (I-M) suppression by muscarinic M-1, but not bradykinin B-2, receptors. In this study, we first explored whether purinergic and angiotensin suppression of I-M in superior cervical ganglion (SCG) sympathetic neurons involves AKAP79/150. Transfection into rat SCG neurons of Delta A-AKAP79, which lacks the A domain necessary for PKC binding, or the absence of AKAP150 in AKAP150(-/-) mice, did not affect I-M suppression by purinergic agonist or by bradykinin, but reduced I-M suppression by muscarinic agonist and angiotensin II. Transfection of AKAP79, but not Delta A-AKAP79 or AKAP15, rescued suppression of I-M by muscarinic receptors in AKAP150(-/-) neurons. We also tested association of AKAP79 with M-1, B-2, P2Y(6), and AT(1) receptors, and KCNQ2 and KCNQ3 channels, via Forster resonance energy transfer (FRET) on Chinese hamster ovary cells under total internal refection fluorescence microscopy, which revealed substantial FRET between AKAP79 and M-1 or AT(1) receptors, and with the channels, but only weak FRET with P2Y(6) or B-2 receptors. The involvement of AKAP79/150 in G(q/11)-coupled muscarinic regulation of N- and L-type Ca2+ channels and by cAMP/protein kinase A was also studied. We found AKAP79/150 to not play a role in the former, but to be necessary for forskolin-induced upregulation of L-current. Thus, AKAP79/150 action correlates with the PIP2 (phosphatidylinositol 4,5-bisphosphate)-depletion mode of I-M suppression, but does not generalize to G(q/11)-mediated inhibition of N- or L-type Ca2+ channels.
- 出版日期2011-5-11
