WDR5 modulates cell motility and morphology and controls nuclear changes induced by a 3D environment

Abstract

Abstract:Cell migration through extracellular matrices requires nuclear deformation, which depends on nuclear stiffness. In turn, chromatin structure contributes to nuclear stiffness, but the mechanosensing pathways regulating chromatin during cell migration remain unclear. Here, we demonstrate that WD repeat domain 5 (WDR5), an essential component of H3K4 methyltransferase complexes, regulates cell polarity, nuclear deformability and migration of lymphocytes in vitro and in vivo, independent of transcriptional activity, suggesting non-genomic functions for WDR5. Similarly, depletion of RbBP5 (another H3K4 methyltransferase subunit) promotes similar defects. We reveal that a 3D environment increases the H3K4 methylation dependent on WDR5, and results in a globally less compacted chromatin conformation. Further, using atomic force microscopy, nuclear particle tracking and nuclear swelling experiments, we detect changes in nuclear mechanics that accompany the epigenetic changes induced in 3D conditions. Indeed, nuclei from cells in 3D environments were softer, and thereby more deformable, compared to cells in suspension or cultured in 2D conditions, again dependent on WDR5. Dissecting the underlying mechanism, we determined that actomyosin contractility, through the phosphorylation of myosin by MLCK (myosin light chain kinase), controls the interaction of WDR5 with other components of the methyltransferase complex, which in turn upregulates H3K4 methylation activation in 3D conditions. Taken together, our findings reveal a novel non-genomic function for WDR5 in regulating H3K4 methylation induced by 3D environments, physical properties of the nucleus, cell polarity and cell migratory capacity. 3 Significance:Cells require nuclear deformation to squeeze through tissue matrices. We have discovered that WDR5 (an epigenetic modulator of H3K4 methylation) is fundamental for cell polarity and migration in vitro and in vivo, independently of transcription. We have uncovered that the interactions between cells and the surrounding 3D confined conditions induce the upregulation of H3K4me3. Moreover, 3D environments control the deformability and the mechanical properties of the nucleus. We have identified that loss of WDR5 abrogates the H3K4 methylation and the nuclear changes induced by 3D conditions. Mechanistically, we found that MLCK and myosin function was required for WDR5-mediated H3K4 methylation in 3D matrices. Our findings uncover new functions of the epigenetic machinery when cells move through constricted conditions.

Novel contribution of epigenetic changes to nuclear dynamics

“…Aligning with these studies, we have previously described that epigenetic changes related with closed chromatin conformation alter the mechanical properties and shape of nuclei from lymphocytes and leukemia cells [21]. Now, we have extended these results and described how increased levels of a euchromatin marker (H3K4 methylation) are linked to the biomechanical properties of isolated nuclei from cells moving in 3D environments [22].…”

“…to demonstrate that chromatin structure contributes, independently of its transcriptional activity, to the shape, size and mechanical properties that govern nuclear deformability [13,23,24]. Through atomic force microscopy (AFM) and nuclear multiparticle tracking (NMPT) we have recently revealed that nuclei from cells in suspension or from cells in 2D culture present different stiffness and viscosity than nuclei from cells moving in 3D [22]. Our findings suggest that chromatin decompaction induced by confined conditions decreases nuclear stiffness.…”

“…We have described how G9a activity (a histone H3K9 methyltransferase) is also important for transendothelial migration of acute leukemia cells [38]. Our studies indicate that a dense collagen matrix promotes H3K4 methylation in leukocytes [22]. Furthermore, we could show that the inhibition or silencing of WDR5 (WD Repeat Domain 5), a core subunit of the histone H3K4 methyltransferase, diminishes the number of cells with highly deformable nuclei [22].…”

Lymphocyte mechanotransduction: The regulatory role of cytoskeletal dynamics in signaling cascades and effector functions

“…3D collagen matrices induced methylation of histone 3, lysine 4 residue (H3K4) by methyltransferases, and this methylation increased as a function of collagen density. H3K4 methylation in T cells in 3D environments was associated with less dense chromatin structure, deformable and less stiff nuclei, and lower nuclear viscosity . This mechanism operated through the WD repeat‐containing protein 5 (WDR5) subunit of methyltransferases.…”

“…H3K4 methylation in T cells in 3D environments was associated with less dense chromatin structure, deformable and less stiff nuclei, and lower nuclear viscosity. 66 This mechanism operated through the WD repeat-containing protein 5 (WDR5) subunit of methyltransferases. Importantly, the cytoskeleton was shown to couple the methylation of H3K4 through WDR5 in a 3D environment, shedding light on a novel mechanotransducing role for WDR5 in T cells.…”