MAPK相互作用丝苏氨酸激酶2通过调控巨噬细胞影响心肌重构的机制研究

Macrophages play critical roles in cardiac remodeling. The MAP kinase-interacting serine/threonine kinase 2 (Mnk2) is one of the kinases that could be activated by MAP kinase. Mnk2 is involved in regulating the phosphorylation state of eukaryotic initiation factor 4E (eIF4E), the eukaryotic initiation factor 4G (eIF4G), the PTB (polypyrimidine tractbinding protein)-associated splicing factor (PSF) and Sprouty2, and regulating macrophage function. However, the role of Mnk2 in cardiac remodeling is still unclear. One of our research showed that Mnk1, the orthologue of Mnk2, carries out a suppressive function in cardiac remodeling via regulating Sprouty2/ERK1/2 pathway. Our pre-experiment demonstrated that Mnk2 gene knockout (Mnk2-KO) mice exhibited enlarged hearts after aortic banding (AB) as compared to the wild type mice. We also found that there were more CD45+ and F4/80+ cells in the myocardium of Mnk2-KO mice after 4 weeks of AB. More importantly, we found that after angiotensin Ⅱ or lipopolysaccharide stimulation, Mnk2 mRNA expression decreased significantly in macrophages, while it did not change in cardiomyocytes or cardiac fibroblasts. We speculate that Mnk2 may affect cardiac remodeling through regulating macrophage function. In this study, we intend to establish pressure overload-induced cardiac remodeling models using Mnk2-KO mice, to evaluate the effect of Mnk2 on cardiac remodeling through cardiac function detection, gross heart observation, histological analysis and molecular markers detection, and to explore the underlying mechanisms. And we intend to conduct macrophage culture and adenovirus infection, trying to figure out if Mnk2 could directly affect macrophage function. We also intend to conduct coculture of macrophages and primary cardiomyocytes or cardiac fibroblasts, trying to figure out if Mnk2 could affect cardiomyocyte hypertrophy, cardiac fibroblast proliferation, transdifferentiation and collagen production through regulating macrophage function. The study is designed to elucidate the role of Mnk2 in cardiac remodeling and the underlying mechanisms associated with macrophages, and to provide new experimental evidence and targets for clinical intervention of cardiac remodeling and heart failure.

巨噬细胞在心肌重构中发挥重要作用。MAPK相互作用丝苏氨酸激酶2（MAP kinase-interacting serine/threonine kinase 2，Mnk2）是MAPK激活的蛋白激酶之一。其可磷酸化多个底物，还可调控巨噬细胞功能，但其对心肌重构的影响未见报道。我们的预实验初步提示：Mnk2基因敲除加重小鼠心肌重构可能与巨噬细胞密切相关，故提出假设：Mnk2可通过调控巨噬细胞功能参与心肌重构。本项目拟用Mnk2基因敲除小鼠，于在体水平研究Mnk2在心肌重构中的作用及机制；应用小鼠巨噬细胞培养和腺病毒转染技术，于离体水平探讨Mnk2对巨噬细胞功能的影响及机制；应用巨噬细胞与心肌细胞/成纤维细胞共培养技术，研究Mnk2通过调控巨噬细胞功能对心肌细胞肥大、炎症，及心肌成纤维细胞增殖、转分化和胶原合成的影响。力图明确Mnk2在心肌重构中的作用和机制，为心肌重构的防治提供理论工作基础。

MAPK相互作用丝苏氨酸激酶2（MAP kinase-interacting serine/threonine kinase 2，Mnk2）是MAPK激活的蛋白激酶之一，其可磷酸化多个底物，还可调控巨噬细胞功能本项目拟明确Mnk2在心肌重构中的作用和机制，为临床干预心肌重构提供理论工作基础；本课题的研究内容为①应用Mnk2基因敲除小鼠和C57BL/6野生型小鼠，建立压力负荷诱导的小鼠心肌重构模型，明确Mnk2基因对压力负荷诱导的小鼠心肌重构的影响；②从巨噬细胞增殖、迁移、极化三个方面阐明Mnk2基因通过巨噬细胞调控心肌重构的具体作用机制，并提出其可能涉及的分子机制；本课题发现，Mnk2基因敲除可加重压力负荷诱导的心肌重构，增加以炎症介导为主要功能的巨噬细胞的浸润、增加巨噬细胞的增殖、造成巨噬细胞向介导炎症为主要功能的方向极化，并可能通过P-selectin、VLA-4和LFA-1促进炎症相关巨噬细胞从血液中向心肌组织迁移，相关过程可能与Mnk2的底物Sprouty2和PSF有关；本研究可为心肌重构的分子机制的阐明提供理论工作基础，并可为临床干预心肌重构提供新策略方向。