The Spatiotemporal Dynamics of the Small GTPase ARL13B during Mitosis in Microglia
SHEN Jiahao1, CHEN Jiaxin2, ZHANG Rong2, HUA Junrui3, HE Jinpeng3*, WEI Li4*
The small GTPase ARL13B plays a crucial role in the formation and functional maintenance of primary cilia, yet its functions in other cellular processes remain poorly understood. In this study, immunofluorescence staining analyses of ARL13B and γ-tubulin are conducted in microglia and glioblastoma cells. It is found that ARL13B is not only specifically expressed on primary cilia but also begins to accumulate at the equatorial plate during metaphase of mitosis. Subsequently, it sequentially forms ring-like and double-rod structures in cytokinetic bridge midzone, ultimately distributing into daughter cells. Immunofluorescence staining of spindle microtubules and midbody microtubules (α-tubulin) displays that ARL13B sequentially accumulates at the cleavage furrow, contractile ring, and the middle region of the midbody, termed the stem body, starting from the anaphase of mitosis, indicating the involvement of ARL13B in regulating the mitotic process. Furthermore, during the telophase of mitosis in microglia cells, the ring-like or double-rod ARL13B structures consistently stay in the stem body region, with their ends connected to the termini of midbody microtubules on both sides. However, in glioblastoma cells ARL13B not only accumulates in the stem body region but also exhibits extensive colocalization with the midbody microtubules on both sides. Further investigation demonstrates that inhibiting ARL13B protein expression by siRNA significantly reduces the proportion of cells in telophase during mitosis and leads to an obvious decline in cell proliferation. This study shows the spatiotemporal dynamics of ARL13B distribution during mitosis in microglia, and provides preliminary evidence for its novel function in regulating the mitotic process.
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