Cadherin 6 promotes neural crest cell detachment via F-actin regulation and influences active Rho distribution during epithelial-to-mesenchymal transition

Abstract

The epithelial-to-mesenchymal transition (EMT) is a complex change in cell phenotype that is important for cell migration, morphogenesis and carcinoma metastasis. Loss of epithelial cell adhesion and tight regulation of cadherin adhesion proteins are crucial for EMT. Cells undergoing EMT often display cadherin switching, where they downregulate one cadherin and induce expression of another. However, the functions of the upregulated cadherins and their effects on cell motility are poorly understood. Neural crest cells (NCCs), which undergo EMT during development, lose N-cadherin and upregulate Cadherin 6 (Cdh6) prior to EMT. Cdh6 has been suggested to suppress EMT via cell adhesion, but also to promote EMT by mediating pro-EMT signals. Here, we determine novel roles for Cdh6 in generating cell motility during EMT. We use live imaging of NCC behavior in vivo to show that Cdh6 promotes detachment of apical NCC tails, an important early step of EMT. Furthermore, we show that Cdh6 affects spatiotemporal dynamics of F-actin and active Rho GTPase, and that Cdh6 is required for accumulation of F-actin in apical NCC tails during detachment. Moreover, Cdh6 knockdown alters the subcellular distribution of active Rho, which is known to promote localized actomyosin contraction that is crucial for apical NCC detachment. Together, these data suggest that Cdh6 is an important determinant of where subcellular actomyosin forces are generated during EMT. Our results also identify mechanisms by which an upregulated cadherin can generate cell motility during EMT.

Cadherin-6 promotes EMT and cancer metastasis by restraining autophagy

“…As a result of this multifunctional activity, CDH6 promotes EMT, collective cell migration and metastasization of thyroid cancer. Even if further experiments are needed, this model is in accordance with the previously described activity of CDH6 in EMT 22,24 and is supported by a consistent number of works reporting an inhibitory function of autophagy on the activation of the EMT program, 44 and a relevant role of the DRP1-dependent mitochondrial fission in promoting cancer migration and aggressiveness. [45][46][47][48] EMT and autophagy are linked in a controversial and still undefined relationship.…”

“…In accordance with our data, these authors show that ablation of CDH6 results in altered spatiotemporal dynamics of F-actin filaments and in particular in the loss of apical accumulation of actin filaments, which is a necessary event for cell migration. 24 CDH6 silencing attenuates EMT phenotype in thyroid cancer cells Recently, we described CDH6 as a marker of EMT in thyroid cancer 22 and we showed here that its expression changes cell-cell interaction. Thus, we investigated whether silencing of CDH6 affects epithelial-mesenchymal differentiation.…”

Resolving Time and Space Constraints During Neural Crest Formation and Delamination

“…First, its messages persist in the dorsal neural tube after completion of NCC emigration, indicating that its function may not be restricted to the temporal control of intercellular adhesion during EMT (Nakagawa & Takeichi, 1995). In mouse and zebrafish, cadherin-6, a close relative to cadherin-6B, is not downregulated after NCC delamination, and at trunk levels in the chick, cadherin-6B proteins remain present transiently on the surface of early migrating cells (Clay & Halloran, 2014;Inoue, Chisaka, Matsunami, & Takeichi, 1997;Park & Gumbiner, 2010). Additionally, functional studies suggest that, rather than maintaining epithelial stability among NCC, cadherin-6B in chick and cadherin-6 in fish are required for cells to lose their epithelial junctional polarity and acquire their motile properties (Clay & Halloran, 2014;Park & Gumbiner, 2010).…”

“…In zebrafish, the effect is mediated by controlling Rho GTPase distribution in the cytoplasm. Both signaling pathways ultimately regulate locally the organization of the actin cytoskeleton and promote polarized actomyosin contraction necessary for disruption of apical cell junctions (Clay & Halloran, 2014;Park & Gumbiner, 2010, 2012.…”

Molecular Control of the Neural Crest and Peripheral Nervous System Development

“…Modulation of cadherins, integrins, and multiple extracellular matrix (ECM) components is vital for modulating NCC delamination (Perris & Perissinotto, 2000). For example, a regulated switch from N-cadherin to cadherin-6 expression and noncanonical Wnt/planar cell polarity signaling play a key role in delamination and early migration (Carmona-Fontaine, Matthews, & Mayor, 2008; Clay & Halloran, 2014; De Calisto, Araya, Marchant, Riaz, & Mayor, 2005; Mayor & Theveneau, 2014; Nakagawa & Takeichi, 1995, 1998; Ulmer et al, 2013). Wnt/β-catenin signaling also acts as a potent instructive cue that promotes PNS specification.…”