CD38-dependent ADP-ribosyl cyclase activity in developing and adult mouse brain
CD38-dependent ADP-ribosyl cyclase activity in developing and adult mouse brain
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DOI：
10.1042/bj20020604
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发表时间：
2003-02-15
影响因子：
4.1
通讯作者：
Moutin, MJ
中科院分区：
文献类型：
--
作者：
Ceni, C;Pochon, N;Moutin, MJ
CD38 是一种跨膜糖蛋白，在全身许多组织中表达。除了其主要的 NAD(+)-糖水解酶活性外，CD38 还能够从 NAD(+) 合成环状 ADP-核糖，这是一种内源性钙调节分子。在本研究中，我们比较了发育中和成年野生型小鼠和 Cd38(-/-) 小鼠大脑蛋白质提取物中 ADP-核糖基环化酶和 NAD(+)-糖水解酶的活性。在野生型大脑的提取物中，早在胚胎第 15 天，就使用烟酰胺-鸟嘌呤二核苷酸作为底物（GDP-核糖基环化酶活性），通过荧光分光光度法检测了环化酶活性。环化酶活性水平在新生儿大脑中相似（出生后第 1 天），然后在成人大脑中大大增加。使用[C-14]NAD(+)作为底物和HPLC分析，我们发现ADP-核糖是所有发育阶段大脑中形成的主要产物。在相同的实验条件下，在发育中或成年Cd38(-/-)小鼠的大脑提取物中均未检测到NAD(+)-糖水解酶和GDP-核糖基环化酶活性，这表明CD38是所有发育阶段大脑中具有这些活性的主要组成酶。活性测量与发育中和成年野生型小鼠大脑中存在的 CD38 转录物水平相关。使用共聚焦显微镜，我们发现，在海马细胞的原代培养物中，CD38由神经元和神经胶质细胞表达，并且在神经元周核中富集。在海马细胞培养物中测量了细胞内NAD(+)-糖水解酶活性，并且在富含细胞内膜的脑部分中CD38依赖性环化酶活性较高。综上所述，这些结果推测 CD38 除了其质膜位置之外，还可能在神经细胞中具有细胞内位置，并且可能在脑组织中细胞内循环 ADP-核糖介导的钙信号传导中发挥重要作用。
CD38 is a transmembrane glycoprotein that is expressed in many tissues throughout the body. In addition to its major NAD(+)-glycohydrolase activity, CD38 is also able to synthesize cyclic ADP-ribose, an endogenous calcium-regulating molecule, from NAD(+). In the present study, we have compared ADP-ribosyl cyclase and NAD(+)-glycohydrolase activities in protein extracts of brains from developing and adult wild-type and Cd38(-/-) mice. In extracts from wild-type brain, cyclase activity was detected spectrofluorimetrically, using nicotinamide-guanine dinucleotide as a substrate (GDP-ribosyl cyclase activity), as early as embryonic day 15. The level of cyclase activity was similar in the neonate brain (postnatal day 1) and then increased greatly in the adult brain. Using [C-14]NAD(+) as a substrate and HPLC analysis, we found that ADP-ribose is the major product formed in the brain at all developmental stages. Under the same experimental conditions, neither NAD(+)-glycohydrolase nor GDP-ribosyl cyclase activity could be detected in extracts of brains from developing or adult Cd38(-/-) mice, demonstrating that CD38 is the predominant constitutive enzyme endowed with these activities in brain at all developmental stages. The activity measurements correlated with the level of CD38 transcripts present in the brains of developing and adult wild-type mice. Using confocal microscopy we showed, in primary Cultures of hippocampal cells, that CD38 is expressed by both neurons and glial cells, and is enriched in neuronal perikarya. Intracellular NAD(+)-glycohydrolase activity was measured in hippocampal cell cultures, and CD38-dependent cyclase activity was higher in brain fractions enriched in intracellular membranes. Taken together, these results lead its to speculate that CD38 might have an intracellular location in neural cells in addition to its plasma membrane location, and may play in important role in intracellular cyclic ADP-ribose-mediated calcium signalling in brain tissue.