#2474 TPPP3 maintains the stability of foot cytoskeleton architecture

Abstract Background and Aims Podocytes have a unique cytoskeleton architecture, and the disturbance of the skeleton architecture can lead to foot processes fusion and then proteinuria. Actin microfilaments dominate the cytoskeleton of the foot process, and microtubules and intermediate filaments dominate the synapses of the foot cells. The structural destruction of foot process actin is closely related to the injury of podocytes. The microtubule and actin often work together in cellular processes through stable connections. As the core structure of the skeleton network, microtubules play a key role in supporting and maintaining the skeleton network. However, the mechanism of microtubule structure destruction and podocyte injury remains unclear. Method Immunofluorescence and western blot were used to confirm the correlation between actin injury and decreased acetylation of tubulin in podocytes in vitro and in vivo. Single-cell RNA sequencing comprehensively characterized the expression of TPPP3 in human glomeruli. Immunofluorescence, immunohistochemical, western blot were used to determine the expression of TPPP3, α-tubulin, acetylated tubulin, actin microfilaments. Results In the case of podocyte injury, the acetylation level of tubulin decreased (P < 0.05). Reducing tubulin acetylation can lead to microfilaments injury (P < 0.05) and weakened podocyte motility (P < 0.05). TPPP3 was specifically expressed in human glomerular podocytes, and its expression level was significantly decreased after podocyte injury (P < 0.05). Knockdown of TPPP3 leaded to the level of microtubule acetylation decreased (P < 0.05) and microfilaments were damaged (P < 0.05) in podocytes. High acetylation levels of tubulin can partially restore actin microfilament damage caused by TPPP3 reduction in vivo and in vitro (P < 0.05). Conclusion TPPP3 is involved in maintaining the normal morphology and function of podocytes by stabilizing the actin microfilament skeleton structure by regulating the acetylation level of microtubules.