{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\nMIR4676, as characterized through studies of the EFA6 family proteins, functions as a specific guanine nucleotide exchange factor (GEF) for ARF6. This activity is critical for initiating ARF6-dependent processes including membrane remodeling, vesicular trafficking, and interactions with the actin cytoskeleton. In the central nervous system, distinct EFA6 isoforms show differential spatiotemporal expression and subcellular localization—findings that suggest a fine-tuned regulation of ARF6 signaling during neuronal development and synaptic function."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}]}, {"type": "t", "text": ""}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nWithin neurons, MIR4676-related proteins are found concentrated in specialized subcellular compartments. Abundant localization at postsynaptic densities, dendritic spines, and perisynaptic processes reveals their involvement not only in facilitating ARF6 activation but also in orchestrating interactions with cytoskeletal regulators such as α‐actinin and sorting nexin-1. Such interactions underpin processes ranging from receptor internalization and synaptic plasticity to neurite extension, as evidenced by analyses in retinal, hippocampal, and forebrain tissues."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "3", "end_ref": "5"}]}, {"type": "t", "text": ""}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nFurthermore, MIR4676-related EFA6 proteins participate in endocytic pathways by recruiting partners such as endophilin, which is critical for clathrin-mediated vesicle formation and membrane curvature modulation. This coordination facilitates proper receptor recycling and growth factor signaling, for example in nerve growth factor (NGF)-dependent pathways, thereby influencing neurite outgrowth and sustaining neuronal survival. Direct interactions with proteins involved in membrane fission and uncoating further underscore their role in vesicular trafficking dynamics."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "6"}]}, {"type": "t", "text": ""}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nIn addition to their roles in membrane and vesicular traffic, MIR4676-related proteins contribute to cytoskeletal regulation. For instance, a specialized N-terminal motif found in some of these proteins is capable of binding tubulin directly and inhibiting microtubule growth, which can modulate axonal growth cone dynamics and axon branching. Similar regulatory mechanisms appear to influence not only neuronal microtubule organization but also membrane trafficking in skeletal muscle cells, underscoring a broader functional repertoire in both neuronal and non-neuronal cell types."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "8"}]}, {"type": "t", "text": ""}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Hiroyuki Sakagami, Hiroharu Suzuki, Akifumi Kamata, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Distinct spatiotemporal expression of EFA6D, a guanine nucleotide exchange factor for ARF6, among the EFA6 family in mouse brain."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Brain Res (2006)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1016/j.brainres.2006.02.058"}], "href": "https://doi.org/10.1016/j.brainres.2006.02.058"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "16707115"}], "href": "https://pubmed.ncbi.nlm.nih.gov/16707115"}]}, {"type": "r", "ref": 2, "children": [{"type": "t", "text": "Hiroyuki Sakagami, Takashi Honma, Jun Sukegawa, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Somatodendritic localization of EFA6A, a guanine nucleotide exchange factor for ADP-ribosylation factor 6, and its possible interaction with alpha-actinin in dendritic spines."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Eur J Neurosci (2007)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1111/j.1460-9568.2007.05345.x"}], "href": "https://doi.org/10.1111/j.1460-9568.2007.05345.x"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "17298598"}], "href": "https://pubmed.ncbi.nlm.nih.gov/17298598"}]}, {"type": "r", "ref": 3, "children": [{"type": "t", "text": "Osamu Katsumata, Takashi Honma, Masashi Sanda, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Predominant localization of EFA6A, a guanine nucleotide exchange factor for ARF6, at the perisynaptic photoreceptor processes."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Brain Res (2008)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1016/j.brainres.2008.07.093"}], "href": "https://doi.org/10.1016/j.brainres.2008.07.093"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "18708035"}], "href": "https://pubmed.ncbi.nlm.nih.gov/18708035"}]}, {"type": "r", "ref": 4, "children": [{"type": "t", "text": "Ryoji Suzuki, Sachiko Saino-Saito, Hiroyuki Sakagami, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Localization of EFA6A, a guanine nucleotide exchange factor for ARF6, in spermatogenic cells of testes of adult mice."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Mol Histol (2009)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1007/s10735-008-9207-9"}], "href": "https://doi.org/10.1007/s10735-008-9207-9"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "19085064"}], "href": "https://pubmed.ncbi.nlm.nih.gov/19085064"}]}, {"type": "r", "ref": 5, "children": [{"type": "t", "text": "Masahiro Fukaya, Daisuke Fukushima, Yoshinobu Hara, et al. "}, {"type": "b", "children": [{"type": "t", "text": "EFA6A, a guanine nucleotide exchange factor for Arf6, interacts with sorting nexin-1 and regulates neurite outgrowth."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Neurochem (2014)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1111/jnc.12524"}], "href": "https://doi.org/10.1111/jnc.12524"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "24261326"}], "href": "https://pubmed.ncbi.nlm.nih.gov/24261326"}]}, {"type": "r", "ref": 6, "children": [{"type": "t", "text": "Sonia Boulakirba, Eric Macia, Mariagrazia Partisani, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Arf6 exchange factor EFA6 and endophilin directly interact at the plasma membrane to control clathrin-mediated endocytosis."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Proc Natl Acad Sci U S A (2014)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1073/pnas.1401186111"}], "href": "https://doi.org/10.1073/pnas.1401186111"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "24979773"}], "href": "https://pubmed.ncbi.nlm.nih.gov/24979773"}]}, {"type": "r", "ref": 7, "children": [{"type": "t", "text": "Masahiro Fukaya, Kanta Ibuchi, Takeyuki Sugawara, et al. "}, {"type": "b", "children": [{"type": "t", "text": "EFA6A, an Exchange Factor for Arf6, Regulates NGF-Dependent TrkA Recycling From Early Endosomes and Neurite Outgrowth in PC12 Cells."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Traffic (2024)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1111/tra.12936"}], "href": "https://doi.org/10.1111/tra.12936"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "38725127"}], "href": "https://pubmed.ncbi.nlm.nih.gov/38725127"}]}, {"type": "r", "ref": 8, "children": [{"type": "t", "text": "Yue Qu, Ines Hahn, Meredith Lees, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Efa6 protects axons and regulates their growth and branching by inhibiting microtubule polymerisation at the cortex."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Elife (2019)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.7554/eLife.50319"}], "href": "https://doi.org/10.7554/eLife.50319"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "31718774"}], "href": "https://pubmed.ncbi.nlm.nih.gov/31718774"}]}, {"type": "r", "ref": 9, "children": [{"type": "t", "text": "Surang Chomphoo, Hiroyuki Sakagami, Hisatake Kondo, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Localization of EFA6A, an exchange factor for Arf6, in Z-lines and sarcoplasmic reticulum membranes in addition to myofilaments in I-domains of skeletal myofibers of peri-natal mice."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Acta Histochem (2024)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1016/j.acthis.2024.152187"}], "href": "https://doi.org/10.1016/j.acthis.2024.152187"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "39126836"}], "href": "https://pubmed.ncbi.nlm.nih.gov/39126836"}]}]}]}