Yuan Ze, Li Qi, Bai Xue, Zhang Kai, He Jinlong, Ai Ding, Cui Qinghua, Zhu Yi, Li Bochuan
The Province and Ministry Co-Sponsored Collaborative Innovation Center for Medical Epigenetics (Z.Y., J.H., D.A., Y.Z., B.L.), Tianjin Medical University, China.
NHC Key Laboratory of Hormones and Development (Z.Y., J.H., D.A., Y.Z., B.L.), Tianjin Medical University, China.
Circ Res. 2025 Aug;137(4):519-532. doi: 10.1161/CIRCRESAHA.125.326233. Epub 2025 Jul 1.
The CEMIP (cell migration-inducing protein) exhibits extremely high expression levels in smooth muscle tissues. However, whether CEMIP modulates the contractile phenotype of vascular smooth muscle cells and confers blood pressure remains elusive.
To explore the role of CEMIP in SMCs, we generated a mouse model with SMC-specific CEMIP deficiency (SMC-). By combining coimmunoprecipitation assay and molecular docking prediction, we identified MLC20 (myosin light chain 20) and its phosphatase, PP1c (protein phosphatase 1c) as binding proteins for CEMIP. To elucidate the mechanism by which CEMIP interacts with MLC20 and PP1c, bioluminescence resonance energy transfer assay and motif mutation were utilized to unravel the intricate network.
CEMIP is abundantly expressed in smooth muscle tissues including the mesenteric artery, aorta, and intestine. In a serum-starved contractile phenotype, SMCs responded to serum stimulation by gradually decreasing CEMIP expression, as they shifted to a secretory phenotype. The mice lacking CEMIP in SMCs showed significantly reduced contractility and blood pressure compared with their counterparts of age-matched wild-type littermates (). Mechanistically, we demonstrated that CEMIP directly interacted with MLC20 to maintain its phosphorylation. In addition, CEMIP sequestered MLC20 from its phosphatase, PP1c, without affecting the kinase MLCK (myosin light chain kinase). Moreover, CEMIP contains 3 critical RVxF (consensus sequence RxxQV/I/LK/RxY/W) motifs that are responsible for binding to PP1c. Mutations in these motifs restored the interaction between PP1c and MLC20.
CEMIP functions as a gatekeeper for maintaining the contractile phenotype of SMCs via the PP1c-MLC20 cascade. CEMIP is indispensable for maintaining blood pressure.
CEMIP（细胞迁移诱导蛋白）在平滑肌组织中表达水平极高。然而，CEMIP是否调节血管平滑肌细胞的收缩表型并影响血压仍不清楚。
为了探究CEMIP在平滑肌细胞中的作用，我们构建了平滑肌细胞特异性CEMIP缺陷的小鼠模型（SMC-）。通过免疫共沉淀实验和分子对接预测，我们鉴定出肌球蛋白轻链20（MLC20）及其磷酸酶蛋白磷酸酶1c（PP1c）为CEMIP的结合蛋白。为了阐明CEMIP与MLC20和PP1c相互作用的机制，利用生物发光共振能量转移实验和基序突变来揭示这一复杂网络。
CEMIP在包括肠系膜动脉、主动脉和肠道在内的平滑肌组织中大量表达。在血清饥饿的收缩表型中，平滑肌细胞在向分泌表型转变时，通过逐渐降低CEMIP表达来响应血清刺激。与年龄匹配的野生型同窝小鼠相比，平滑肌细胞中缺乏CEMIP的小鼠收缩力和血压显著降低。机制上，我们证明CEMIP直接与MLC20相互作用以维持其磷酸化。此外，CEMIP将MLC20与其磷酸酶PP1c隔离，而不影响激酶肌球蛋白轻链激酶（MLCK）。而且，CEMIP包含3个关键的RVxF（一致序列RxxQV/I/LK/RxY/W）基序，负责与PP1c结合。这些基序的突变恢复了PP1c与MLC20之间的相互作用。
CEMIP通过PP1c-MLC20级联反应作为维持平滑肌细胞收缩表型的守门人。CEMIP对维持血压必不可少。
