Ninewells Hospital, University of Dundee, Scotland, UK.
Biochem J. 2010 Nov 15;432(1):153-63. doi: 10.1042/BJ20101188.
Mammalian PKD (protein kinase D) isoforms have been implicated in the regulation of diverse biological processes in response to diacylglycerol and PKC (protein kinase C) signalling. To compare the functions of PKD1 and PKD2 in vivo, we generated mice deficient in either PKD1 or PKD2 enzymatic activity, via homozygous expression of PKD1(S744A/S748A) or PKD2(S707A/S711A) 'knockin' alleles. We also examined PKD2-deficient mice generated using 'gene-trap' technology. We demonstrate that, unlike PKD1, PKD2 catalytic activity is dispensable for normal embryogenesis. We also show that PKD2 is the major PKD isoform expressed in lymphoid tissues, but that PKD2 catalytic activity is not essential for the development of mature peripheral T- and B-lymphocytes. PKD2 catalytic activity is, however, required for efficient antigen receptor-induced cytokine production in T-lymphocytes and for optimal T-cell-dependent antibody responses in vivo. Our results reveal a key in vivo role for PKD2 in regulating the function of mature peripheral lymphocytes during adaptive immune responses. They also confirm the functional importance of PKC-mediated serine phosphorylation of the PKD catalytic domain for PKD activation and downstream signalling and reveal that different PKD family members have unique and non-redundant roles in vivo.
哺乳动物 PKD（蛋白激酶 D）同工型已被牵涉到调节各种生物过程，以响应二酰基甘油和 PKC（蛋白激酶 C）信号。为了比较 PKD1 和 PKD2 在体内的功能，我们通过纯合表达 PKD1（S744A/S748A）或 PKD2（S707A/S711A）“敲入”等位基因，生成了缺乏 PKD1 或 PKD2 酶活性的小鼠。我们还检查了使用“基因捕获”技术生成的 PKD2 缺陷型小鼠。我们证明，与 PKD1 不同，PKD2 的催化活性对于正常胚胎发生是可有可无的。我们还表明，PKD2 是淋巴组织中主要表达的 PKD 同工型，但 PKD2 的催化活性对于成熟外周 T 和 B 淋巴细胞的发育不是必需的。然而，PKD2 的催化活性对于 T 淋巴细胞中抗原受体诱导的细胞因子产生和体内最佳 T 细胞依赖性抗体反应是必需的。我们的结果揭示了 PKD2 在调节适应性免疫反应期间成熟外周淋巴细胞功能方面的关键体内作用。它们还证实了 PKC 介导的 PKD 催化结构域丝氨酸磷酸化对于 PKD 激活和下游信号转导的功能重要性，并揭示了不同的 PKD 家族成员在体内具有独特且不可替代的作用。
