Involvement of Receptor-Mediated S1P Signaling in EGF-Induced Macropinocytosis in COS7 Cells.

Involvement of Receptor-Mediated S1P Signaling in EGF-Induced Macropinocytosis in COS7 Cells. Kobe J Med Sci. 2020 Nov 17;66(3):E94-E101 Authors: Matovelo SA, Zhang L, Mohamed NNI, Kajimoto T, Ijuin T, Okada T, Nakamura SI Abstract Macropinocytosis is a highly conserved cellular process of endocytosis by which extracellular fluid and nutrients are taken up into cells through large, heterogeneous vesicles known as macropinosomes. Growth factors such as epidermal growth factor (EGF) can induce macropinocytosis in many types of cells, although precise mechanism underlying EGF-induced macropinocytosis remains unclear. In the present studies we have shown the involvement of S1P signaling in EGF-induced macropinocytosis in COS7 cells. First, EGF-induced macropinocytosis was strongly impaired in sphingosine kinase isozymes, SphK1 or SphK2-depleted cells, which was completely rescued by the expression of the corresponding wild-type isozyme but not the catalytically inactive one, suggesting the involvement of sphingosine 1-phosphate (S1P) in this phenomenon. Next, we observed that EGF-induced macropinocytosis was strongly inhibited in S1P type 1 receptor (S1P1R)-knockdown cells, implying involvement of S1P1R in this event. Furthermore, we could successfully demonstrate EGF-induced trans-activation of S1P1R using one-molecular fluorescence resonance energy transfer (FRET) technique. Moreover, for EGF-induced Rac1 activation, a step essential t...
Source: Kobe J Med Sci - Category: General Medicine Authors: Tags: Kobe J Med Sci Source Type: research