cAMP/protein kinase A signalling pathway protects against neuronal apoptosis and is associated with modulation of Kv2.1 in cerebellar granule cells.
Previously, we have reported that apoptosis of cerebellar granular neurons induced by incubation in 5 mm K(+) and serum-free medium (LK-S) was associated with an increase in the delayed rectifier K(+) current (I(K)). Here, we show that I(K) associated with apoptotic neurons is mainly encoded by a Kv2.1 subunit. Silencing Kv2.1 expression by small interfering RNA reduces I(K) and increases neuron viability. Forskolin is able to decrease the I(K) amplitude recording from neurons of both the LK-S and control group, and prevents apoptosis of granule cells that are induced by LK-S. Dibutyryl cAMP mimicks the effect of forskolin on the modulation of I(K) and, accordingly, the inhibitor of protein kinase A, H-89, aborts the neuron-protective effect induced by forskolin. Whereas the expression of Kv2.1 was silenced by Kv2.1 small interfering RNA, the inhibition of forskolin on the current amplitude was significantly reduced. Quantitative RT-PCR and whole-cell recording revealed that the expression of Kv2.1 was elevated in the apoptotic neurons, and forskolin significantly depressed the expression of Kv2.1. We conclude that the protection against apoptosis via the protein kinase A pathway is associated with a double modulation on I(K) channel properties and its expression of alpha-subunit that is mainly encoded by the Kv2.1 gene.
Jiao
Song
S
The Institute of Brain Science, School of Life Sciences, Fudan University, Shanghai, China.
Liu
Zheng
Z
Ren
Wen-Hua
WH
Ding
Yu
Y
Zhang
Yu-Qiu
YQ
Zhang
Zhi-Hong
ZH
Mei
Yan-Ai
YA
D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology*; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000502:physiology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D004347:Drug Interactions; D004558:Electric Stimulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques / Q000379:methods; D011189:Potassium Chloride / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000494:pharmacology; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D051669:Shab Potassium Channels / Q000235:genetics / Q000502:physiology*; D014162:Transfection / Q000379:methods
D004791:Enzyme Inhibitors; D034741:RNA, Small Interfering; D051669:Shab Potassium Channels; D005576:Colforsin; D011189:Potassium Chloride; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases