biostudies-literatureSoh WCNational Research Foundation of Korea (NRF)National Cancer CenterNational Cancer Center (NCC)National Research Foundation of Koreae2505291122https://www.ebi.ac.uk/biostudies/studies/S-EPMC12318239biostudies-literatureUnknown122(30)Microvilli on T cells differ from those on epithelial cells, exhibiting filopodia-like characteristics that facilitate the clustering of molecules essential for sensing and cell migration. Recently, they have also been recognized as the structures from which T cell immunological synaptosomes (TIS) are released. In this study, we examined a key determinant of microvilli organization during T cell development and explored the functional roles of these structures, particularly in relation to T cell behaviors. During thymocyte maturation, single-positive thymocytes were found to develop more and longer microvilli than double-positive thymocytes. However, the deletion or inhibition of Cdc42, a small Rho family protein, significantly reduced both the number and length of microvilli in single-posProceedings of the National Academy of Sciences of the United States of America<i>Cdc42</i> defect reveals insights into microvilli organization and function in T cell immunity.PMC12318239RS-2024-00419699RS-2024-0034-0032RS-2024-003418692022R1A2C4002627NCC-2310600-32015R1A3A2066253Park SMLee SKim MSPark JJun CDKarabulut HKang HTSoh WCKim HRPark JSKang SKfalse<i>Cdc42</i> defect reveals insights into microvilli organization and function in T cell immunity.Microvilli on T cells differ from those on epithelial cells, exhibiting filopodia-like characteristics that facilitate the clustering of molecules essential for sensing and cell migration. Recently, they have also been recognized as the structures from which T cell immunological synaptosomes (TIS) are released. In this study, we examined a key determinant of microvilli organization during T cell development and explored the functional roles of these structures, particularly in relation to T cell behaviors. During thymocyte maturation, single-positive thymocytes were found to develop more and longer microvilli than double-positive thymocytes. However, the deletion or inhibition of Cdc42, a small Rho family protein, significantly reduced both the number and length of microvilli in single-pos2025-01-01T00:00:00Z2025 Jul2026-06-02T10:04:23.442Z2025-08-12T03:04:28.439ZS-EPMC123182394071191610.1073/pnas.2505291122