Millward T A, Heizmann C W, Schäfer B W, Hemmings B A
Friedrich Miescher-Institut, Maulbeerstrasse 66, CH-4058 Basel.
EMBO J. 1998 Oct 15;17(20):5913-22. doi: 10.1093/emboj/17.20.5913.
Ndr is a nuclear serine/threonine protein kinase that belongs to a subfamily of kinases identified as being critical for the regulation of cell division and cell morphology. The regulatory mechanisms that control Ndr activity have not been characterized previously. In this paper, we present evidence that Ndr is regulated by EF-hand calcium-binding proteins of the S100 family, in response to changes in the intracellular calcium concentration. In vitro, S100B binds directly to and activates Ndr in a Ca2+-dependent manner. Moreover, Ndr is recovered from cell lysates in anti-S100B immunoprecipitates. The region of Ndr responsible for interaction with Ca2+/S100B is a basic/hydrophobic motif within the N-terminal regulatory domain of Ndr, and activation of Ndr by Ca2+/S100B is inhibited by a synthetic peptide derived from this region. In cultured cells, Ndr is rapidly activated following treatment with Ca2+ ionophore, and this activation is dependent upon the identified Ca2+/S100B-binding domain. Finally, Ndr activity is inhibited by W-7 in melanoma cells overexpressing S100B, but is unaffected by W-7 in melanoma cells that lack S100B. These results suggest that Ndr is regulated at least in part by changes in the intracellular calcium concentration, through binding of S100 proteins to its N-terminal regulatory domain.
Ndr是一种核丝氨酸/苏氨酸蛋白激酶，属于一个激酶亚家族，该亚家族被认为对细胞分裂和细胞形态的调节至关重要。此前尚未对控制Ndr活性的调节机制进行过描述。在本文中，我们提供证据表明，Ndr受S100家族的EF-手型钙结合蛋白调节，以响应细胞内钙浓度的变化。在体外，S100B以Ca2+依赖的方式直接结合并激活Ndr。此外，在抗S100B免疫沉淀物中可从细胞裂解物中回收Ndr。Ndr中负责与Ca2+/S100B相互作用的区域是Ndr N端调节域内的一个碱性/疏水基序，并且来自该区域的合成肽可抑制Ca2+/S100B对Ndr的激活。在培养细胞中，用Ca2+离子载体处理后Ndr迅速被激活，并且这种激活依赖于已确定的Ca2+/S100B结合域。最后，在过表达S100B的黑色素瘤细胞中，W-7可抑制Ndr活性，但在缺乏S100B的黑色素瘤细胞中，W-7对其活性没有影响。这些结果表明，Ndr至少部分受细胞内钙浓度变化的调节，通过S100蛋白与其N端调节域的结合来实现。
