Distinct and nonoverlapping roles for pRB and cyclin D: cyclin-dependent kinases 4/6 activity in melanocyte survival
Distinct and nonoverlapping roles for pRB and cyclin D: cyclin-dependent kinases 4/6 activity in melanocyte survival
复制标题
DOI：
10.1073/pnas.2431391100
复制
发表时间：
2003-12-09
影响因子：
11.1
通讯作者：
Dowdy, SF
中科院分区：
文献类型：
--
作者：
Yu, BD;Becker-Hapak, M;Dowdy, SF
p16（INK 4a）-细胞周期蛋白D：细胞周期蛋白依赖性激酶（cdk）4/6-视网膜母细胞瘤（pRB）通路的失调是人类细胞致癌转化的常见范例，表明该通路在恶性转化中线性发挥作用。然而，目前尚不清楚为什么p16（INK 4a）和细胞周期蛋白D：cdk 4/6突变比人类恶性肿瘤（如黑色素瘤）中罕见的RB失活遗传事件更常见。为了更好地了解这些复合物如何有助于改变组织的稳态，我们阻断了cdk 4/6激活和急性失活的Rb在小鼠毛囊周期的条件突变。通过皮下施用膜可转导的TAT-p16（INK 4a）蛋白来抑制皮肤中的cdk 4/6完全阻断毛囊生长和分化。相比之下，通过皮下注射TAT-Cre重组酶对纯合子Rb-LoxP/LoxP小鼠皮肤中Rb的急性破坏未能影响毛发生长。然而，Rb的损失导致严重的毛囊色素脱失。进一步分析滤泡黑素细胞在体内和原代细胞培养证明，pRB发挥细胞自主的作用，黑素细胞的生存。此外，功能失活的所有三个Rb家族成员（Rb，p107，和p130）在原代黑素细胞的治疗与可转导的TAT-E1 A蛋白没有拯救凋亡表型。这些研究结果表明，去调节的细胞周期蛋白D：cdk 4/6复合物和pRB在体内执行非重叠的功能，并提供了一种细胞机制，占癌症，如黑色素瘤的RB失活的发病率低。
Deregulation of the p16(INK4a)-cyclin D:cyclin-dependent kinases (cdk) 4/6-retinoblastoma (pRB) pathway is a common paradigm in the oncogenic transformation of human cells and suggests that this pathway functions linearly in malignant transformation. However, it is not understood why p16(INK4a) and cyclin D:cdk4/6 mutations are disproportionately more common than the rare genetic event of RB inactivation in human malignancies such as melanoma. To better understand how these complexes contribute to altered tissue homeostasis, we blocked cdk4/6 activation and acutely inactivated Rb by conditional mutagenesis during mouse hair follicle cycling. Inhibition of cdk4/6 in the skin by subcutaneous administration of a membrane-transducible TAT-p16(INK4a) protein completely blocked hair follicle growth and differentiation. In contrast, acute disruption of Rb in the skin of homozygous Rb-LoxP/LoxP mice via subcutaneous administration of TAT-Cre recombinase failed to affect hair growth. However, loss of Rb resulted in severe depigmentation of hair follicles. Further analysis of follicular melanocytes in vivo and in primary cell culture demonstrated that pRB plays a cell-autonomous role in melanocyte survival. Moreover, functional inactivation of all three Rb family members (Rb, p107, and p130) in primary melanocytes by treatment with a transducible TAT-E1A protein did not rescue the apoptotic phenotype. These findings suggest that deregulated cyclin D:cdk4/6 complexes and pRB perform nonoverlapping functions in vivo and provide a cellular mechanism that accounts for the low incidence of RB inactivation in cancers such as melanoma.