biostudies-literatureGaeta IMAmerican Heart AssociationBLRD VANICHD NIH HHSNational Institute of Diabetes and Digestive and Kidney DiseasesNIDDK NIH HHSNational Institutes of HealthU.S. Department of Veterans AffairsNIH HHSNIGMS NIH HHS2561-2575.e6https://www.ebi.ac.uk/biostudies/studies/S-EPMC8222192biostudies-literatureUnknown31(12)Microvilli are actin-bundle-supported surface protrusions that play essential roles in diverse epithelial functions. To develop our understanding of microvilli biogenesis, we used live imaging to directly visualize protrusion growth at early stages of epithelial differentiation. Time-lapse data revealed that specific factors, including epidermal growth factor pathway substrate 8 (EPS8) and insulin-receptor tyrosine kinase substrate (IRTKS) (also known as BAIAP2L1), appear in diffraction-limited puncta at the cell surface and mark future sites of microvillus growth. New core actin bundles elongate from these puncta in parallel with the arrival of ezrin and subsequent plasma membrane encapsulation. In addition to de novo growth, we also observed that new microvilli emerge from pre-existing pCurrent biology : CBDirect visualization of epithelial microvilli biogenesis.PMC8222192IK2 BX004885R01-DK111949P30 DK058404R01 DK125546T32 HD007502R01-DK095811R01 DK095811R01 DK111949S10 OD012324F31DK1226925T32HD007502-20T32 GM0085541IK2-BX004885F31 DK122692T32-A1007474Gaeta IMMeenderink LMPostema MMTyska MJCencer CSfalseDirect visualization of epithelial microvilli biogenesis.Microvilli are actin-bundle-supported surface protrusions that play essential roles in diverse epithelial functions. To develop our understanding of microvilli biogenesis, we used live imaging to directly visualize protrusion growth at early stages of epithelial differentiation. Time-lapse data revealed that specific factors, including epidermal growth factor pathway substrate 8 (EPS8) and insulin-receptor tyrosine kinase substrate (IRTKS) (also known as BAIAP2L1), appear in diffraction-limited puncta at the cell surface and mark future sites of microvillus growth. New core actin bundles elongate from these puncta in parallel with the arrival of ezrin and subsequent plasma membrane encapsulation. In addition to de novo growth, we also observed that new microvilli emerge from pre-existing p2021-01-01T00:00:00Z2021 Jun2026-05-09T03:08:35.517Z2025-02-18T23:32:08.124ZS-EPMC82221923395145610.1016/j.cub.2021.04.012