Acyl coenzyme A-binding protein (ACBP) is phosphorylated and secreted by retinal Muller astrocytes following protein kinase C activation.
Acyl coenzyme A-binding protein (ACBP) is phosphorylated and secreted by retinal Muller astrocytes following protein kinase C activation.
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酰基辅酶 A 结合蛋白 (ACBP) 在蛋白激酶 C 激活后由视网膜 Muller 星形胶质细胞磷酸化并分泌。
DOI：
10.1111/j.1471-4159.2008.05229.x
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发表时间：
2008
影响因子：
4.7
通讯作者：
Barmack,NealH
中科院分区：
文献类型：
--
作者：
Qian,Zuyuan;Bilderback,TimothyR;Barmack,NealH
水平视动刺激兔视网膜蛋白vivoevoke增加表达的酰基辅酶A结合蛋白（ACBP），也被称为'地西泮结合抑制剂，'从视网膜米勒细胞。如果表达的ACBP也由Müller细胞分泌，那么刺激诱发的ACBP分泌可能影响表达GABA A受体的视网膜神经元的活性。在这项研究中，我们在体外研究了在高水平的KCl和佛波醇肉豆蔻酸酯（PMA）刺激后，Müller胶质细胞和Müller样QNR/K2细胞是否分泌ACBP。KCl和PMA刺激诱发苏氨酸磷酸化ACBP的分泌。序列分析表明，ACBP有5个潜在的磷酸化位点：2个苏氨酸位点符合蛋白激酶C磷酸化模式。两个苏氨酸位点符合酪蛋白激酶II（CK 2）模式。一个丝氨酸位点符合CK 2模式。由于CK 2在QNR/K2细胞中不表达，因此蛋白激酶C可能解释了这些细胞中ACBP的磷酸化和PMA诱导的ACBP分泌。丝氨酸磷酸化是组成性的。水平视动刺激增加兔视网膜中苏氨酸磷酸化ACBP。ACBP的磷酸化可能影响其靶向亲和力。我们使用ACBP的蛋白水解片段，十八碳神经肽（ODN），研究苏氨酸磷酸化如何影响其对GABAA受体的亲和力。与未磷酸化的ODN或未磷酸化的ACBP相比，三磷酸化的ODN对GABAA受体具有更强的亲和力。我们得出结论，刺激诱导的Müller细胞分泌磷酸化ACBP可能影响邻近视网膜神经元的GABA能传递。
Horizontal optokinetic stimulation of rabbit retinain vivoevokes increased expression of acyl coenzyme A‐binding protein (ACBP), also known as ‘diazepam binding inhibitor,’ from retinal Müller cells. If the expressed ACBP were also secreted by Müller cells, then stimulus‐evoked secretion of ACBP could influence the activity of GABAAreceptor‐expressing retinal neurons. In this study, we examinein vitrowhether ACBP is secreted by Müller glial cells and Müller‐like QNR/K2 cells following stimulation with elevated levels of KCl and phorbol myristic acetate (PMA). KCl and PMA stimulation evoked secretion of threonine‐phosphorylated ACBP. A sequence analysis of ACBP shows that it has five potential phosphorylation sites: Two threonine sites fit a protein kinase C phosphorylation pattern. Two threonine sites fit a casein kinase II (CK2) pattern. One serine site fits a CK2 pattern. As CK2 is not expressed in QNR/K2 cells, it is probable that protein kinase C accounts for the phosphorylation of ACBP in these cells and for the PMA‐evoked secretion of ACBP. Serine phosphorylation was constitutive. Horizontal optokinetic stimulation increased threonine‐phosphorylated ACBP in rabbit retina. Phosphorylation of ACBP may influence its target affinity. We used a proteolytic fragment of ACBP, octadecaneuropeptide (ODN), to investigate how threonine phosphorylation influences its affinity for GABAAreceptors. Threonine‐phosphorylated ODN had a stronger affinity for GABAAreceptors than did unphosphorylated ODN or unphosphorylated ACBP. We conclude that stimulus‐induced Müller cell secretion of phosphorylated ACBP could influence the GABAergic transmission in neighboring retinal neurons.