The Actin Crosslinker Fascin Regulates Cell Chirality

Abstract The left–right (L‐R) asymmetry of the cells, or cell chirality, is a well‐known intrinsic property derived from the dynamic organization of the actin cytoskeleton. Cell chirality can be regulated by actin‐binding proteins such as α‐actinin‐1 and can also be mediated by certain signaling pathways, such as protein kinase C (PKC) signaling. Fascin, an actin crosslinker known to mediate parallel bundling of actin filaments, appears as a prominent candidate in cell chirality regulation, given its role in facilitating cell migration as an important PKC substrate. Here, it is shown that the chirality of NIH/3T3 cells can be altered by PKC activation and fascin manipulation. With either small‐molecule drug inhibition or genetic knockdown of fascin, the chirality of 3T3 cells is reversed from a clockwise (CW) bias to a counterclockwise (CCW) bias on ring‐shaped micropatterns, accompanied by the reversal in cell directional migration. The Ser‐39 fascin‐actin binding sites are further explored in cell chirality regulation. The findings of this study reveal the critical role of fascin as an important intermediator in cell chirality, shedding novel insights into the mechanisms of L‐R asymmetric cell migration and multicellular morphogenesis.