The Regulatory Role Of KIF4A In The Expression Of Angiogenesis-associated Factors Of Macrophages

BackgroundMacrophages are derived from monocytes and polarize into classical activated M1 cells and alternative activated M2 cells,depending on different external stimulation.The phenotypes and functions between two macrophage subsets are significantly different.M1 cells show strong activities of phagocytosis and proinflammatory cytokines secretion,while M2 cells secret multiple kinds of cytokines and angiogenesis-associated factors,and promote tumor progression.The regulation activities of angiogenesis of macrophages are important factors of tumor progression,and also the target of tumor therapy.The cellular transportation and secretion depend on the dynamic rearrangement of the cytoskeleton and the movement of transport proteins.Kinesin is a family of motor protein composed of microtubules and is involved in variant important physiological activities,including the transportation of membranous organelles,proteins and mRNA.Variant members of KIF family have been found in macrophages.However,it is still not clear whether the KIF members are involved in the secretion of angiogenesis-associated factors of macrophages.Therefore,in this study we analyzed the secretion of angiogenesis-associated factors and also the expression of KIF family members in M0,M1 and M2 macrophages subsets.Moreover,we explored the role of KIF4A in the secretion of angiogenesis-associated factors of macrophages by knocking down its expression.Method1.THP-1 monocyte was differentiated into MO macrophages by PMA stimulation,and polarized into M1 cells by LPS and IFN-?,and M2 cells by IL-4.2.To analyze KIF family members in M0.M1 and M2 cells by RT-PCR.3.To knock down KIF4A expression in M0,M1 and M2 cells by siRNA transfection and knock-down efficiency was testified by RT-PCR.4.To analyze the expression of angiogenesis-associated factors in three macrophage subsets by ELISA.Results1.LIF,VEGF,sVEGFR1 and TIMP1 was found in MO cells,while sVEGFR2,Flt-3,Leptin,LeptinR and CD40L expression was not explored.2.No significant change of LIF,VEGF,sVEGFRl and TIMP1 expression was found during the polarization from MO intoMl cells,and only sVEGFR1 expression was significantly increased during the polarization from MO into M2 cells.3.KIF4A expression was found in all three macrophage subsets.KIF4A expression was significantly decreased by KIF4A siRNA transfection.4.No significant change of LIF,VEGF,sVEGFR1 and TIMP1 expression was found in MO and Ml cells after KIF4A knockdown.The expression of LIF,VEGF and TIMP1 expression was also not significantly changed in M2 cells but sVEGFR1 expression was significantly decreased.ConclusionOur study analyzed the expression of angiogenesis-associated factors in three macrophage subsets.We found LIF,VEGF,sVEGFR1 and TIMP1 expression in MO cells.We found no significant change of the expression of these angiogenesis-associated factors during the polarization into Ml cells,but sVEGFR1 was increased during the polarization into M2 cells.sVEGFR1 expression in M2 cells was significantly inhibited by KIF4A knockdown.The above results suggested that KIF4A promoted sVEGFR1 expression in M2 cells and therefore regulated their angiogenesis activities.Our findings provide valuable evidences for the regulation of angiogenesis activities of macrophages,and help to understand the important roles of KIFs family members in macrophages functions.