Opposing Growth Regulatory Roles of Protein Kinase D Isoforms in Human Keratinocytes
Opposing Growth Regulatory Roles of Protein Kinase D Isoforms in Human Keratinocytes
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DOI：
10.1074/jbc.m115.643742
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发表时间：
2015-04-24
影响因子：
4.8
通讯作者：
Ghazizadeh, Soosan
中科院分区：
文献类型：
--
作者：
Ryvkin, Vladislav;Rashel, Mohammad;Ghazizadeh, Soosan
PKD是一个由三种丝氨酸/苏氨酸激酶（PKD-1、PKD-2和PKD-3）组成的家族，参与调节包括增殖、迁移、分泌和细胞存活在内的多种生物学过程。我们以前已经表明，尽管所有三种亚型在小鼠表皮中表达，PKD 1在伤口愈合，佛波酯诱导的增生和肿瘤发展中起着独特的关键作用。在将我们的研究结果转化为人类时，我们发现PKD 1在人类角质形成细胞（KC）中不表达，并且其他PKD亚型的表达和功能存在分歧。与小鼠KC相反，用PKD的药理学抑制剂处理培养的人KC导致生长停滞。我们发现PKD 2和PKD 3在增殖和分化的人KC中表达差异，前者均匀地存在于两个隔室中，而后者主要在增殖隔室中表达。敲除人KC中的单个PKD亚型揭示了PKD 2和PKD 3的相反的生长调节作用。PKD 2的缺失增强了KC的增殖潜力，而PKD 3的缺失导致了进行性增殖缺陷、克隆形成能力的丧失和组织再生能力的降低。这种增殖缺陷与CDK 4/6抑制剂p15（INK 4 B）的上调和诱导p53非依赖性G1期细胞周期阻滞相关。PKD亚型的同时沉默导致更明显的增殖缺陷，这与PKD 3在增殖KC中的主要作用一致。这些数据强调了PKD信号在人表皮中的重要性和复杂性，并表明PKD 3信号在维持人表皮稳态中的核心作用。
PKD is a family of three serine/threonine kinases (PKD-1, -2, and -3) involved in the regulation of diverse biological processes including proliferation, migration, secretion, and cell survival. We have previously shown that despite expression of all three isoforms in mouse epidermis, PKD1 plays a unique and critical role in wound healing, phorbol ester-induced hyperplasia, and tumor development. In translating our findings to the human, we discovered that PKD1 is not expressed in human keratinocytes (KCs) and there is a divergence in the expression and function of other PKD isoforms. Contrary to mouse KCs, treatment of cultured human KCs with pharmacological inhibitors of PKDs resulted in growth arrest. We found that PKD2 and PKD3 are expressed differentially in proliferating and differentiating human KCs, with the former uniformly present in both compartments whereas the latter is predominantly expressed in the proliferating compartment. Knockdown of individual PKD isoforms in human KCs revealed contrasting growth regulatory roles for PKD2 and PKD3. Loss of PKD2 enhanced KC proliferative potential while loss of PKD3 resulted in a progressive proliferation defect, loss of clonogenicity and diminished tissue regenerative ability. This proliferation defect was correlated with up-regulation of CDK4/6 inhibitor p15(INK4B) and induction of a p53-independent G1 cell cycle arrest. Simultaneous silencing of PKD isoforms resulted in a more pronounced proliferation defect consistent with a predominant role for PKD3 in proliferating KCs. These data underline the importance and complexity of PKD signaling in human epidermis and suggest a central role for PKD3 signaling in maintaining human epidermal homeostasis.