The role of Arf6, a low molecular weight G protein, in various physiological functions in individuals has been extensively studied. Arf6 is known to be involved in the dynamics of cell membranes through the transport of vesicles between the cell membrane and endosomes, as well as the reconstruction of the actin cytoskeleton. When cells receive stimuli such as growth factors or hormones, the GDP bound to Arf6 dissociates and is replaced by GTP, activating Arf6. This activation has been reported to control the recycling of proteins such as β1 integrin, glucose transporter 4 (Glut4), and transmembrane heparan sulfate proteoglycan syndecan involved in extracellular matrix adhesion.

The role of Arf6, a low molecular weight G protein, in various physiological functions in individuals has been extensively studied. Arf6 is known to be involved in the dynamics of cell membranes through the transport of vesicles between the cell membrane and endosomes, as well as the reconstruction of the actin cytoskeleton. When cells receive stimuli such as growth factors or hormones, the GDP bound to Arf6 dissociates and is replaced by GTP, activating Arf6. This activation has been reported to control the recycling of proteins such as β1 integrin, glucose transporter 4 (Glut4), and transmembrane heparan sulfate proteoglycan syndecan involved in extracellular matrix adhesion.

In this phenomenon, ACAP1, one of the Arf6 GAPs, plays a crucial role as an effector molecule of Arf6. It is also known that Arf6 binds to Sec10, a subunit of the exocyst complex that controls vesicle transport to the cell membrane. Multiple steps are believed to be involved in the recycling of membrane proteins by Arf6.

Arf6 is involved in various cellular processes that involve membrane dynamics, such as neurite outgrowth and cell migration. Rac1, another low molecular weight G protein, is an important molecule that controls the reconstruction of the actin cytoskeleton. It functions downstream of Arf6 and regulates cell migration. However, our results have shown that Rac1 also functions upstream of Arf6, indicating that the signaling relationship between Arf6 and Rac1 is complex.

Arf6 is involved in the release of microvesicles containing membrane-bound matrix metalloproteinase 1, which promotes invadopodia formation by recruiting actin cytoskeleton-binding proteins such as cortactin and cell adhesion-related molecule paxillin to the cell membrane. Microvesicle release is a phenomenon in which the cell membrane protrudes outward and pinches off. In this process, phospholipase D (PLD) has been shown to function as a downstream molecule of Arf6.

In order for cancer cells to invade, degradation of the surrounding extracellular matrix is necessary. Arf6 has been reported to be involved in the release of microvesicles containing membrane-bound matrix metalloproteinase 1. Loss of Arf6 impairs HGF-dependent cell migration and membrane dynamics, leading to hepatic cord formation failure, increased apoptosis in the liver, and developmental disorders of the liver. The reduction in the size of the corpus callosum and hippocampal formation observed in NSC-Arf6 cKO mice is concluded to be due to impaired myelination rather than a decrease in the number of axons. NSC-Arf6 cKO mice showed a significant decrease in the number of oligodendrocytes. Arf6 expressed in neurons contributes to the release of guidance factors involved in the recruitment of oligodendrocytes. In fact, the secretion of fibroblast growth factor 2 (FGF2), a guidance factor for oligodendrocytes, was significantly inhibited in the hippocampus extracted from N-Arf6 cKO mice.

Arf6 expressed in endothelial cells is an important factor that controls tumor angiogenesis. Analysis of angiogenesis promoted by vascular endothelial growth factor (VEGF), FGF2, and HGF revealed that Arf6 deficiency specifically inhibits HGF-dependent angiogenesis. In Arf6 KO endothelial cells, the recycling of β1 integrin, induced by HGF, was almost completely inhibited, resulting in the inhibition of HGF-induced endothelial cell adhesion and migration. However, the recycling of β1 integrin induced by VEGF was not inhibited in Arf6 KO endothelial cells.

The cytohesin-Arf6 signaling pathway plays an important role downstream of the insulin receptor. This pathway positively regulates insulin signaling by assisting in the binding between IRS and the insulin receptor, upon binding to the insulin receptor.

In conclusion, Arf6 plays a diverse range of physiological functions in individuals. It is involved in the dynamics of cell membranes, vesicle transport, actin cytoskeleton reconstruction, recycling of membrane proteins, regulation of cell migration, release of microvesicles, and control of angiogenesis. Understanding the intricate signaling pathways and functions of Arf6 can provide valuable insights into various cellular processes and potentially lead to the development of therapeutic strategies for diseases such as cancer and developmental disorders.