Aramburu J, Garcia-Cózar F, Raghavan A, Okamura H, Rao A, Hogan P G
Center for Blood Research, Harvard Medical School, Boston Massachusetts 02115, USA.
Mol Cell. 1998 Apr;1(5):627-37. doi: 10.1016/s1097-2765(00)80063-5.
NFAT transcription factors play a key role in the immune response. The activation of NFAT proteins is controlled by calcineurin, the calmodulin-dependent phosphatase that is inhibited by the immunosuppressive drugs cyclosporin A and FK506. Here we identify a short conserved sequence in NFAT proteins that targets calcineurin to NFAT. Mutation of a single residue in this sequence impairs the calcineurin-mediated dephosphorylation and nuclear translocation of NFAT1. Peptides spanning the region inhibit the ability of calcineurin to bind to and dephosphorylate NFAT proteins, without affecting the phosphatase activity of calcineurin against other substrates. When expressed intracellularly, a corresponding peptide inhibits NFAT dephosphorylation, nuclear translocation, and NFAT-mediated expression in response to stimulation. Thus, disruption of the enzyme-substrate docking interaction that directs calcineurin to NFAT can effectively block NFAT-dependent functions.
NFAT转录因子在免疫反应中起关键作用。NFAT蛋白的激活受钙调神经磷酸酶控制，钙调神经磷酸酶是一种钙调蛋白依赖性磷酸酶，可被免疫抑制药物环孢菌素A和FK506抑制。在此，我们在NFAT蛋白中鉴定出一个短的保守序列，该序列将钙调神经磷酸酶靶向至NFAT。此序列中单个残基的突变会损害钙调神经磷酸酶介导的NFAT1去磷酸化及核转位。跨越该区域的肽段会抑制钙调神经磷酸酶与NFAT蛋白结合并使其去磷酸化的能力，而不影响钙调神经磷酸酶对其他底物的磷酸酶活性。当在细胞内表达时，相应的肽段会抑制NFAT去磷酸化、核转位以及刺激后NFAT介导的表达。因此，破坏将钙调神经磷酸酶导向NFAT的酶 - 底物对接相互作用可有效阻断NFAT依赖性功能。
