Enhanced desensitization followed by unusual resensitization in GABAA receptors in phospholipase C-related catalytically inactive protein-1/2 double-knockout mice
- 277 Downloads
Phospholipase C-related catalytically inactive proteins (PRIP-1/2) are previously reported to be involved in the membrane trafficking of GABAA receptor (GABAAR) and the regulation of intracellular Ca2+ stores. GABAAR-mediated currents can be regulated by the intracellular Ca2+. However, in PRIP-1/2 double-knockout (PRIP-DKO) mice, it remains unclear whether the kinetic properties of GABAARs are modulated by the altered regulation of intracellular Ca2+ stores. Here, we investigated whether GABAAR currents (IGABA) evoked by GABA puff in layer 3 (L3) pyramidal cells (PCs) of the barrel cortex are altered in PRIP-DKO mice. The deletion of PRIP-1/2 enhanced the desensitization of IGABA but induced a hump-like tail current (tail-I) at the GABA puff offset. IGABA and the hump-like tail-I were suppressed by GABAAR antagonists. The enhanced desensitization of IGABA and the hump-like tail-I in PRIP-DKO PCs were mediated by increases in the intracellular Ca2+ concentration and were largely abolished by a calcineurin inhibitor and ruthenium red. Calcium imaging revealed that Ca2+-induced Ca2+ release (CICR) and subsequent store-operated Ca2+ entry (SOCE) are more potent in PRIP-DKO PCs than in wild-type PCs. A mathematical model revealed that a slowdown of GABA-unbinding rate and an acceleration of fast desensitization rate by enhancing its GABA concentration dependency are involved in the generation of hump-like tail-Is. These results suggest that in L3 PCs of the barrel cortex in PRIP-DKO mice, the increased calcineurin activity due to the potentiated CICR and SOCE enhances the desensitization of GABAARs and slows the GABA-unbinding rate, resulting in their unusual resensitization following removal of GABA.
KeywordsPRIP GABAA receptor Desensitization Calcineurin Ca2+-induced Ca2+ release Store-operated Ca2+ entry
The authors thank Dr. N. Akaike for critically reviewing an earlier version of the manuscript. This study was supported by a Grant-in-Aid for Scientific Research to Y.K. (B; 22300127) and that to M.H. (S; 24229009) from Japan Ministry of Education, Culture, Sports, Science and Technology.
Conflict of interest
Authors declare no conflict of interest.
- 9.Harada K, Takeuchi H, Oike M, Matsuda M, Kanematsu T, Yagisawa H, Nakayama KI, Maeda K, Erneux C, Hirata M (2005) Role of PRIP-1, a novel Ins(1,4,5)P3 binding protein, in Ins(1,4,5)P3-mediated Ca2+ signaling. J Cell Physiol 202:422–433. doi: 10.1002/jcp.20136, PMID: 15468068PubMedCrossRefGoogle Scholar
- 23.Kanematsu T, Jang IS, Yamaguchi T, Nagahama H, Yoshimura K, Hidaka K, Matsuda M, Takeuchi H, Misumi Y, Nakayama K, Yamamoto T, Akaike N, Hirata M, Nakayama K (2002) Role of the PLC-related, catalytically inactive protein p130 in GABAA receptor function. EMBO J 21:1004–1011. doi: 10.1093/emboj/21.5.1004, PMID: 11867528PubMedCentralPubMedCrossRefGoogle Scholar
- 25.Kincaid RL, Balaban CD, Billingsley ML (1987) Differential localization of calmodulin-dependent enzymes in rat brain: evidence for selective expression of cyclic nucleotide phosphodiesterase in specific neurons. Proc Natl Acad Sci U S A 84:1118–1122, PMID: 3029762PubMedCentralPubMedCrossRefGoogle Scholar
- 28.Martina M, Mozrzymas JW, Boddeke HW, Cherubini E (1996) The calcineurin inhibitor cyclosporin A-cyclophilin A complex reduces desensitization of GABAA-mediated responses in acutely dissociated rat hippocampal neurons. Neurosci Lett 215:95–98. doi: 10.1016/0304-3940(96)12957-8, PMID: 8888004PubMedCrossRefGoogle Scholar
- 30.Mizokami A, Kanematsu T, Ishibashi H, Yamaguchi T, Tanida I, Takenaka K, Nakayama KI, Fukami K, Takenawa T, Kominami E, Moss SJ, Yamamoto T, Nabekura J, Hirata M (2007) Phospholipase C-related inactive protein is involved in trafficking of γ2 subunit-containing GABAA receptors to the cell surface. J Neurosci 27:1692–1701. doi: 10.1523/JNEUROSCI.3155-06.2007, PMID: 17301177PubMedCrossRefGoogle Scholar
- 31.Mizokami A, Tanaka H, Ishibashi H, Umebayashi H, Fukami K, Takenawa T, Nakayama KI, Yokoyama T, Nabekura J, Kanematsu T, Hirata M (2010) GABAA receptor subunit alteration-dependent diazepam insensitivity in the cerebellum of phospholipase C-related inactive protein knockout mice. J Neurochem 114:302–310. doi: 10.1111/j.1471-4159.2010.06754.x, PMID: 20412381PubMedGoogle Scholar
- 34.Muller MS, Obel LF, Waagepetersen HS, Schousboe A, Bak LK (2013) Complex actions of ionomycin in cultured cerebellar astrocytes affecting both calcium-induced calcium release and store-operated calcium entry. Neurochem Res 38:1260–1265. doi: 10.1007/s11064-013-1021-4, PMID: 23519933PubMedCrossRefGoogle Scholar
- 40.Takenaka K, Fukami K, Otsuki M, Nakamura Y, Kataoka Y, Wada M, Tsuji K, Nishikawa S, Yoshida N, Takenawa T (2003) Role of phospholipase C-L2, a novel phospholipase C-like protein that lacks lipase activity, in B-cell receptor signaling. Mol Cell Biol 23:7329–7338. doi: 10.1128/MCB.23.20.7329-7338.2003, PMID: 14517301PubMedCentralPubMedCrossRefGoogle Scholar