Celsr1 and Celsr2 exhibit distinct adhesive interactions and contributions to planar cell polarity

Abstract

Cadherin EGF LAG seven-pass G-type receptor (Celsr) proteins 1-3 comprise a subgroup of adhesion GPCRs whose functions range from planar cell polarity (PCP) signaling to axon pathfinding and ciliogenesis. Like its Drosophila ortholog, Flamingo, mammalian Celsr1 is a core component of the PCP pathway, which, among other roles, is responsible for the coordinated alignment of hair follicles across the skin surface. Although the role of Celsr1 in epidermal planar polarity is well established, the contribution of the other major epidermally expressed Celsr protein, Celsr2, has not been investigated. Here, using two new CRISPR/Cas9-targeted Celsr1 and Celsr2 knockout mouse lines, we define the relative contributions of Celsr1 and Celsr2 to PCP establishment in the skin. We find that Celsr1 is the major Celsr family member involved in epidermal PCP. Removal of Celsr1 function alone abolishes PCP protein asymmetry and hair follicle polarization, whereas epidermal PCP is unaffected by loss of Celsr2. Further, elimination of both Celsr proteins only minimally enhances the Celsr1−/− phenotype. Using FRAP and junctional enrichment assays to measure differences in Celsr1 and Celsr2 adhesive interactions, we find that compared to Celsr1, which stably enriches at junctional interfaces, Celsr2 is much less efficiently recruited to and immobilized at junctions. As the two proteins seem equivalent in their ability to interact with core PCP proteins Vangl2 and Fz6, we suggest that perhaps differences in homophilic adhesion contribute to the differential involvement of Celsr1 and Celsr2 in epidermal PCP.

A Van Gogh/Vangl tyrosine phosphorylation switch regulates its interaction with core Planar Cell Polarity factors Prickle and Dishevelled

“…We then used fluorescence recovery after photocbleaching (FRAP) to determine the mobility of Celsr1 and Vangl2 proteins located within the junctional membrane. Compared to Celsr1 and Vangl2 proteins located at free edges of the cell, Celsr1 and Vangl2 were largely immobile at cell junctions (~80% immobile fraction)(S7B-S7C Fig), as previously shown [36,57]. Mutation of Vangl2 Y308 to A (equivalent to Drosophila VangY374A) did not affect orientation in adult wings of Vang 6 mutant flies (same region as in A'-B) upon rescue with tubulin-promoter expressed Vang-Flagx3 transgenes with WT (wild-type), Y374A, Y374F or V376A, respectively as indicated.…”

Cord Blood Proteomic Profiles, Birth Weight, and Early Life Growth Trajectories

“… 62 Second, CELSR2 has roles in epithelial planar cell polarity and ciliogenesis. 63 CELSR2-deficient mice had a poor cerebrospinal fluid circulation and hydrocephalus. 64 To our knowledge, no literature is available on the association of cord blood CELSR2 levels with birth weight and childhood anthropometrics, making our findings novel.…”

“…In in vitro settings, both afamin and vitamin E enhance cortical neuronal survival . Second, CELSR2 has roles in epithelial planar cell polarity and ciliogenesis . CELSR2-deficient mice had a poor cerebrospinal fluid circulation and hydrocephalus .…”

Structure of the extracellular region of the adhesion GPCR CELSR1 reveals a compact module which regulates G protein-coupling

“…It remains to be defined how the known PCP ligands Frizzled and Van Gogh interact with CELSR1 in cis. 12,77 Additionally, CELSR2 has been shown to dimerize in a parallel configuration via its globular CADH9-GAIN CMM and this binding site remains to be determined. 56 One major limitation of our work is that we did not perform the cryo-EM single particle analysis with added calcium, which is ubiquitous in the extracellular space.…”