[Leukocyte-specific protein 1 (LSP1): A key regulator of cytoskeletal dynamics and leukocyte function]

Leukocyte-specific protein 1 (LSP1) is an F-actin binding protein expressed in various leukocytes, including lymphocytes, mononuclear macrophages, and neutrophils. LSP1 is highly conserved across different species. Human LSP1 protein contains 339 amino acids, featuring a Ca²⁺ binding site in the acidic NH2-terminal region and multiple F-actin binding domains along with phosphorylatable sites in the basic COOH-terminal region. Under Ca²⁺ regulation, the COOH-terminal domain of LSP1 binds to F-actin to regulate cell movement and signal transduction. Additionally, LSP1 activates the mitogen-activated protein kinase (MAPK) signaling pathway through phosphorylation mediated by protein kinase C (PKC) and MAPK-activated protein kinase-2, thereby regulating leukocyte proliferation and chemotaxis. The main effects of LSP1 on leukocytes are as follows: LSP1 plays important roles in neutrophil and macrophage migration, affecting cell adhesion, polarization and movement. LSP1 also functions in endothelial cells to regulate leukocyte transendothelial migration. In addition, LSP1 regulates macrophage phagocytosis through interaction with myosin 1e. Moreover, LSP1 regulates leukocyte proliferation and differentiation and plays significant roles in the development of leukemia and other tumors. In summary, LSP1 regulates leukocyte morphology, movement and function through interactions with cytoskeletal and signaling proteins. This review provides a comprehensive summary of these aspects.