S100A11 promotes focal adhesion disassembly via myosin II-driven contractility and Piezo1-mediated Ca²⁺entry

Abstract

S100A11 is a small Ca2+-activatable protein with an established role in different cellular processes involving actin cytoskeleton remodeling, such as cell migration, membrane protrusion formation, and plasma membrane repair. It also displays Ca2+-dependent F-actin binding activity and localizes to actin stress fibers (SFs), but its precise role in regulating these structures remains unclear. Analyzing endogenous S100A11 localization in HeLa and U2OS osteosarcoma cells confirmed SF association but in addition revealed steady localization to stable focal adhesions (FAs), typically at the end of dorsal stress fibers. In contrast, S100A11 levels at FAs increased sharply, but transiently, at the onset of peripheral FA disassembly. Elevating intracellular Ca2+ levels using the Ca2+ ionophore ionomycin reliably stimulated both S100A11 recruitment and subsequent FA disassembly. However, pre-incubation with the non-muscle myosin II (NM II) inhibitor blebbistatin, or with an inhibitor to the stretch-activatable Ca2+ channel Piezo1 effectively suppressed S100A11 recruitment, implicating S100A11 in an actomyosin contractility-driven FA disassembly mechanism involving Piezo1-dependent Ca2+ influx. Applying external mechanical forces on peripheral FAs via a micropipette likewise recruited S100A11 to FAs, even when NM II was inhibited by blebbistatin or in NM IIA knockout cells, corroborating the mechanosensitive recruitment mechanism of S100A11. However, extracellular Ca2+ and Piezo1 function was still indispensable, indicating that NM II-dependent contraction forces act upstream of Piezo1-mediated Ca2+ influx, in turn leading to S100A11 activation and FA recruitment. Moreover, S100A11 knockout cells feature enlarged FAs and display delayed FA disassembly during cell membrane retraction, consistent with impaired FA turnover in these cells. Our results thus demonstrate a novel mechano-sensitive function for S100A11 in promoting actomyosin contractility-driven FA disassembly.

Interplay between the plasma membrane and cell–cell adhesion maintains epithelial identity for correct polarised cell divisions

“…GFP–S100A11 was distributed in the cytoplasm and localised to the cell surface throughout the cell cycle ( Fig. S4A ; ), which is consistent with recent studies of HeLa and U2OS osteosarcoma cells ( Mohammed et al, 2023 preprint). We validated synchronisation efficiency by assessing the accumulation of phosphorylated histone H3 ( Fig.…”

“…The function of S100A11 in mitosis has not been characterised previously. Our recent findings along with previous studies showing that S100A11 is required for plasma membrane remodelling by mediating a dynamic interplay between the plasma membrane and F-actin ( Jaiswal et al, 2014 ; Mohammed et al, 2023 preprint), and the fact S100A11 interacts with E-cadherin ( Guo et al, 2014 ), prompted us to test whether S100A11 function in the regulation of plasma membrane remodelling may influence cell–cell adhesion integrity and F-actin reorganisation during mitosis. Using immunofluorescence and confocal imaging, we conducted a first characterisation of the localisation of S100A11 during the cell cycle, revealing that S100A11 distributes in the cytoplasm and accumulates at the plasma membrane of mitotic polarised MCF-10A cells ( Fig.…”

“…In this experimental context, we investigated the function of the membrane-associated protein S100 Ca 2+ -binding protein A11 (S100A11), which we have recently identified in a proteomic screen of mitotic mammary epithelial cells ( Fankhaenel et al, 2023 ). S100A11 associates with the plasma membrane in a Ca 2+ -dependent manner and has been shown to regulate plasma membrane repair in migrating cells by facilitating dynamic organisation of F-actin and remodelling of the plasma membrane ( Jaiswal et al, 2014 ; Mohammed et al, 2023 preprint). S100A11 is enriched in pseudopodia of metastatic cancer cells and is required for the formation of actin-dependent pseudopodia protrusions and tumour cell migration ( Shankar et al, 2010 ).…”