Osmotic and heat stress-dependent regulation of MLK4β and MLK3 by the CHIP E3 ligase in ovarian cancer cells.
Osmotic and heat stress-dependent regulation of MLK4β and MLK3 by the CHIP E3 ligase in ovarian cancer cells.
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DOI：
10.1016/j.cellsig.2017.07.021
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发表时间：
2017-11
影响因子：
4.8
通讯作者：
Chadee DN
中科院分区：
文献类型：
--
作者：
Blessing NA;Kasturirangan S;Zink EM;Schroyer AL;Chadee DN
MLK3是MLK亚家族中的一员，是一种丝裂原活化蛋白(MAP3K)，激活MAPK信号通路，调节细胞的增殖、侵袭和凋亡等反应。MLK4β是MLK亚家族的另一个成员，研究较少，其β受应激刺激的调节也不是很清楚。本研究探讨了渗透应激、热应激和热休克蛋白90(HSP90)抑制对卵巢癌细胞中MLK4β和MLK3表达的调节。MLK3和MLK4β蛋白水平在长期渗透应激、热应激或暴露于Hsp90抑制剂格尔达那霉素(GA)的条件下下降；并且MLK3蛋白下降的速度快于MLK4β。-与MLK3相似，暴露于热或渗透应激的细胞中MLK4β蛋白的减少是通过一种涉及Hsc70相互作用蛋白(CHIP)的E3连接酶的机制发生的。热休克蛋白70(HSP70)和CHIP过表达均导致多泛素化和内源性MLK4β蛋白减少，体外CHIP可使MLK4β泛素化。在未经处理的细胞和短期暴露于渗透压和热应激的细胞中，小干扰RNA(SiRNA)敲除MLK4β可增加活化的MLK3、c-jun氨基末端激酶和p38MAPK的水平。此外，MLK3与MLK4β结合，这种结合受渗透胁迫的调节。这些结果表明，在对应激刺激的早期反应中，MLK4β与MLK3的结合对调节MLK3活性和MAPK信号转导起重要作用，在长时间的应激暴露后，MLK4β和MLK3蛋白通过依赖于芯片的降解而下降。这些发现揭示了热和渗透胁迫如何调节MLK4β和MLK3，并揭示了MLK4β在调节应激反应中MLK3活性的重要作用。
Mixed Lineage Kinase 3 (MLK3), a member of the MLK subfamily of protein kinases, is a mitogen-activated protein (MAP) kinase kinase kinase (MAP3K) that activates MAPK signalling pathways and regulates cellular responses such as proliferation, invasion and apoptosis. MLK4β, another member of the MLK subfamily, is less extensively studied, and the regulation of MLK4β by stress stimuli is not known. In this study, the regulation of MLK4β and MLK3 by osmotic stress, thermostress and heat shock protein 90 (Hsp90) inhibition was investigated in ovarian cancer cells. MLK3 and MLK4β protein levels declined under conditions of prolonged osmotic stress, heat stress or exposure to the Hsp90 inhibitor geldanamycin (GA); and MLK3 protein declined faster than MLK4β.–Similar to MLK3, the reduction in MLK4β protein in cells exposed to heat or osmotic stresses occurred via a mechanism that involves the E3 ligase, carboxy-terminus of Hsc70-interacting protein (CHIP). Both heat shock protein 70 (Hsp70) and CHIP overexpression led to polyubiquitination and a decrease in endogenous MLK4β protein, and MLK4β was ubiquitinated by CHIP in vitro. In untreated cells and cells exposed to osmotic and heat stresses for short time periods, small interfering RNA (siRNA) knockdown of MLK4β elevated the levels of activated MLK3, c-Jun N-terminal kinase (JNK) and p38 MAPKs. Furthermore, MLK3 binds to MLK4β, and this association is regulated by osmotic stress. These results suggest that in the early response to stressful stimuli, MLK4β-MLK3 binding is important for regulating MLK3 activity and MAPK signalling, and after prolonged periods of stress exposure, MLK4β and MLK3 proteins decline via CHIP-dependent degradation. These findings provide insight into how heat and osmotic stresses regulate MLK4β and MLK3, and reveal an important function for MLK4β in modulating MLK3 activity in stress responses.
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影响因子：
4.8
作者：
Korchnak AC;Zhan Y;Aguilar MT;Chadee DN
通讯作者：
Chadee DN
影响因子：
5.3
作者：
Mota, M;Reeder, M;Bazenet, CE
通讯作者：
Bazenet, CE
DOI：
10.1073/pnas.202365899
发表时间：
2002-10-01
影响因子：
11.1
作者：
Xu, WP;Marcu, M;Neckers, L
通讯作者：
Neckers, L
影响因子：
4.8
作者：
Jiang, JH;Ballinger, CA;Patterson, C
通讯作者：
Patterson, C
影响因子：
16
作者：
Sathyanarayana, P;Barthwal, MK;Rana, A
通讯作者：
Rana, A