Marti F, Xu C W, Selvakumar A, Brent R, Dupont B, King P D
The Immunology Program, Memorial Sloan-Kettering Cancer Center, Cornell University Medical Center, New York, NY 10021, USA.
Proc Natl Acad Sci U S A. 1998 Sep 29;95(20):11810-5. doi: 10.1073/pnas.95.20.11810.
HLA-specific killer cell inhibitory receptors (KIR) are thought to impede natural killer (NK) and T cell activation programs through recruitment of the SH2 domain-containing tyrosine phosphatases, SHP-1 and SHP-2, to their cytoplasmic tails (CYT). To identify other SH2 domain-containing proteins that bind KIR CYT, we used the recently described yeast two-bait interaction trap and a modified version of this system, both of which permit tyrosine phosphorylation of bait proteins. Using these systems, we show that KIR CYT, once phosphorylated by the src-family tyrosine kinase LCK, additionally bind the p85alpha regulatory subunit of phosphatidylinositol (PI) 3-kinase. Furthermore, we show that in an NK cell line, NK3.3, cross-linking of KIR results in recruitment of p85alpha to KIR and activation of PI 3-kinase lipid kinase activity. One consequence of KIR coupling to PI 3-kinase is downstream activation of the antiapoptotic protein kinase AKT. Therefore, in addition to providing negative signals, KIR may also contribute positive signals for NK and T cell growth and/or survival.
人类白细胞抗原（HLA）特异性杀伤细胞抑制性受体（KIR）被认为可通过将含SH2结构域的酪氨酸磷酸酶SHP-1和SHP-2募集至其胞质尾部（CYT）来阻碍自然杀伤（NK）细胞和T细胞的激活程序。为了鉴定其他与KIR CYT结合的含SH2结构域的蛋白质，我们使用了最近描述的酵母双诱饵相互作用陷阱及其改良版本，这两种系统都允许诱饵蛋白发生酪氨酸磷酸化。利用这些系统，我们发现，一旦被src家族酪氨酸激酶LCK磷酸化，KIR CYT还会结合磷脂酰肌醇（PI）3激酶的p85α调节亚基。此外，我们还发现，在NK细胞系NK3.3中，KIR的交联会导致p85α募集至KIR，并激活PI 3激酶的脂质激酶活性。KIR与PI 3激酶偶联的一个结果是抗凋亡蛋白激酶AKT的下游激活。因此，除了提供负性信号外，KIR可能还为NK细胞和T细胞的生长及/或存活提供正性信号。
