Institute of Anatomy and Cell Biology, Justus-Liebig-University, 35392, Giessen, Germany.
Cell Biochem Biophys. 2012 Jul;63(3):211-22. doi: 10.1007/s12013-012-9357-y.
This study investigated the regulation of 14-3-3β binding to PTPIP51 by the tyrosine phosphorylation status of PTPIP51. The tyrosine 176 residue is phosphorylated by c-Src. Up to now, nothing is known about the impact of such well-established phosphorylation events on the interaction profile of PTPIP51 with its partners of the mitogen-activated protein kinase (MAPK) pathway. In human keratinocytes the PTPIP51 phosphorylation was varied by inhibiting the phosphatase activity, thus enhancing the phosphorylation of PTPIP51. Differential blocking of Src kinase family members (despite c-Src) by PP2 increased the activity of c-Src and the tyrosine phosphorylation of PTPIP51 at position 176, which is the substrate of c-Src kinase. The amount of PTPIP51 interactions with 14-3-3β, Raf-1, PTP1B and c-Src was evaluated and the resulting data were compared to an untreated control group. The increased phosphorylation level resulted in a sharp drop of the 14-3-3β/PTPIP51 and 14-3-3β/Raf-1 interaction. Besides the 14-3-3 interaction of PTPIP51, the interaction with the two MAPK modulators, protein kinase A (PKA) and diacylglycerol kinase alpha (DAGKα), are also regulated by the tyrosine phosphorylation status of PTPIP51. Additional immunostaining experiments were done investigating the functional implication on these interactions of the phosphorylation in apoptotic processes. In the pervanadate- and PP2-treated HaCaT cells, higher amounts of apoptotic cells were not detected as compared to the control group. The presented data confirms a tyrosine phosphorylation-dependent interaction of PTPIP51 with 14-3-3β and Raf-1 in vivo and a tyrosine-dependent interaction profile with DAGKα and PKA. The non-interaction of PTPIP51 with 14-3-3 is not sufficient for triggering apoptosis.
这项研究调查了 14-3-3β与 PTPIP51 的结合受 PTPIP51 的酪氨酸磷酸化状态调节的情况。酪氨酸 176 残基被 c-Src 磷酸化。到目前为止，还没有人知道这种已经确立的磷酸化事件对 PTPIP51 与其丝裂原活化蛋白激酶（MAPK）途径的伙伴相互作用谱的影响。在人角质形成细胞中，通过抑制磷酸酶活性来改变 PTPIP51 的磷酸化，从而增强 PTPIP51 的磷酸化。尽管 c-Src 被 PP2 差异阻断Src 激酶家族成员的活性增加了 c-Src 的活性和 PTPIP51 位置 176 的酪氨酸磷酸化，该位置是 c-Src 激酶的底物。评估了 PTPIP51 与 14-3-3β、Raf-1、PTP1B 和 c-Src 的相互作用量，并将得到的数据与未经处理的对照组进行比较。磷酸化水平的增加导致 14-3-3β/PTPIP51 和 14-3-3β/Raf-1 相互作用急剧下降。除了 PTPIP51 与 14-3-3 的相互作用外，PTPIP51 与两种 MAPK 调节剂蛋白激酶 A（PKA）和二酰基甘油激酶α（DAGKα）的相互作用也受 PTPIP51 酪氨酸磷酸化状态的调节。还进行了额外的免疫染色实验，以研究这些相互作用在凋亡过程中的磷酸化的功能意义。与对照组相比，在用过钒酸钠和 PP2 处理的 HaCaT 细胞中，没有检测到更多的凋亡细胞。所呈现的数据证实了 PTPIP51 与 14-3-3β和 Raf-1 之间的酪氨酸磷酸化依赖性相互作用，以及与 DAGKα 和 PKA 的酪氨酸依赖性相互作用谱。PTPIP51 与 14-3-3 之间的非相互作用不足以引发细胞凋亡。
