Phosphorylation of the protein kinase mutated in Peutz-Jeghers cancer syndrome, LKB1/STK11, at Ser431 by p90RSK and cAMP-dependent protein kinase, but not its farnesylation at Cys433, is essential for LKB1 to suppress cell growth
Phosphorylation of the protein kinase mutated in Peutz-Jeghers cancer syndrome, LKB1/STK11, at Ser431 by p90RSK and cAMP-dependent protein kinase, but not its farnesylation at Cys433, is essential for LKB1 to suppress cell growth
复制标题
DOI：
10.1074/jbc.m009953200
复制
发表时间：
2001-06-01
影响因子：
4.8
通讯作者：
Alessi, DR
中科院分区：
文献类型：
--
作者：
Sapkota, GP;Kieloch, A;Alessi, DR
Peutz-Jeghers综合征是一种遗传性癌症综合征，导致受影响的人患肿瘤的风险大大增加，致病基因是一种称为LKB 1的蛋白激酶，预计可作为肿瘤抑制因子发挥作用，LKB 1在细胞中调节的机制尚不清楚。在这里，我们证明了用ERK 1/2或cAMP依赖性蛋白激酶的激活剂刺激大鼠-α或胚胎干细胞诱导内源性表达的LKB 1在Ser（431）处磷酸化，我们目前的药理学和遗传学证据表明，p90（RSK）介导的这种磷酸化反应的激动剂，激活ERK 1/2和cAMP-依赖性蛋白激酶介导了这种磷酸化，其响应于激活腺苷酸环化酶激动剂，LKB 1的Ser（431）位于推定的异戊烯化基序附近，并且我们证明了在293细胞中表达的全长LKB 1通过向Cys添加法呢基而被异戊烯化（433）。我们的数据表明，LKB 1在Ser（431）的磷酸化不影响法尼基化，法尼基化不影响Ser（431）的磷酸化，LKB 1在Ser（431）的磷酸化不改变LKB 1磷酸化自身或肿瘤抑制蛋白p53的活性，也不改变与细胞膜相关的LKB 1的量。将野生型LKB 1重新引入缺乏LKB 1的癌细胞系中抑制生长，但是其中Ser（431）突变为Ala以防止LKB 1磷酸化的LKB 1突变体在抑制生长方面无效。相反，不能被异戊烯化的LKB 1突变体仍然能够抑制细胞的生长。
Peutz-Jeghers syndrome is an inherited cancer syndrome that results in a greatly increased risk of developing tumors in those affected, The causative gene is a protein kinase termed LKB1, predicted to function as a tumor suppressor, The mechanism by which LKB1 is regulated in cells is not known. Here, we demonstrate that stimulation of Rat-a or embryonic stem cells with activators of ERK1/2 or of cAMP-dependent protein kinase induced phosphorylation of endogenously expressed LKB1 at Ser(431), We present pharmacological and genetic evidence that p90(RSK) mediated this phosphorylation in response to agonists that activate ERK1/2 and that cAMP-dependent protein kinase mediated this phosphorylation in response to agonists that activate adenylate cyclase, Ser(431) of LKB1 lies adjacent to a putative prenylation motif, and we demonstrate that full-length LKB1 expressed in 293 cells was prenylated by addition of a farnesyl group to Cys(433). Our data suggest that phosphorylation of LKB1 at Ser(431) does not affect farnesylation and that farnesylation does not affect phosphorylation at Ser(431), Phosphorylation of LKB1 at Ser(431) did not alter the activity of LKB1 to phosphorylate itself or the tumor suppressor protein p53 or alter the amount of LKB1 associated with cell membranes. The reintroduction of wild-type LKB1 into a cancer cell line that lacks LKB1 suppressed growth, but mutants of LKB1 in which Ser(431) was mutated to Ala to prevent phosphorylation of LKB1 were ineffective in inhibiting growth. In contrast, a mutant of LKB1 that cannot be prenylated was still able to suppress the growth of cells.