CASK (LIN2) interacts with Cx43 in wounded skin and their coexpression affects cell migration

Abstract

SummaryVertebrate gap junctions are composed of proteins from the connexin family. Co-immunoprecipitation, in vitro binding and far western experiments demonstrate that mammalian CASK (also known as LIN2) directly interacts with Cx43. Immunoprecipitation studies indicate that the CASK mainly interacts with the hypophosphorylated form of Cx43. Functional co-regulation of these proteins was found in MDCK cells migrating into a scratch wound, where expression of either protein individually inhibits migration but their coexpression abrogates this inhibitory effect. Immunofluorescence shows colocalization of Cx43 and CASK in mouse brain astrocytes and in response to wounding in human foreskin. During wounding, CASK is mobilized to the plasma membrane where it colocalizes with Cx43 and CADM1 1 hour after skin explant wounding. Together, these studies indicate that CASK interaction with Cx43 occurs relatively early in the connexin life cycle and imply a plasma membrane targeting role for the interaction that apparently affects cellular processes including cellular migration and wound healing.

Gap junctions and cancer: communicating for 50 years

“…Some of the functional consequences are being elucidated in more detail. For example, Cx43 can regulate cellular migration via an interaction with calcium/calmodulin-dependent serine protein kinase (CASK; also known as LIN2) 170 , but it is also clear that this and other Cx43 interactions occur through complex protein networks, as reviewed elsewhere 171 . Interactions between Cx43 and other proteins, such as zona occludens 1 (ZO1) 172 , is also of importance for Cx43 channel assembly and regulation specifically during cancer progression.…”

CASK stabilizes neurexin and links it to liprin-α in a neuronal activity-dependent manner

“…Analyses of CASK mutant mice suggest that CASK expression is essential, but that loss of CASK does not affect typical neuronal properties such as membrane excitability, calcium-dependent presynaptic release or post-synaptic receptor localization [4]. CASK is known to interact with several other molecules including kinases [CDK5 [12], CaMKII [34], PKC- [35], PKA [36]], ion channels [calcium ion channel [37], Kir2.1 [38], ether-a-go-go [39], calcium pump 4B/Cl [40]], regulatory proteins [calmodulin [3], rabphilin [41], RGS4 [35]], ubiquitin ligases [Parkin [42]], transcription activators [Tbr-1 [43], Id1 [44]], adhesion molecules [neurexin [3], syndecan [45], SynCAM [46], JAM-1 [47], Neph1 and 2 [48], other scaffolding molecules [Mint1 [13], Veli [13], Dlg, SAP97, GRIP1 [35]], cytoskeletal coupling molecules [protein 4.1 [45], FRMD7 [49] BCl11A/CTIP1 [50]] and the gap junction protein connexin-43 [51]. …”

Kinase programs spatiotemporally regulate gap junction assembly and disassembly: Effects on wound repair

“…Cx43 is abundantly expressed in skin and is known to play a key regulatory role during different stages of the repair process [92–95] via its expression and phosphorylation status changes [78, 96, 97]. Proliferation continually occurs in the basal layer of the epidermis to replace dead keratinocytes and is upregulated dramatically during wounding to provide a source of cells for wound repair.…”

“…For example, wound-dependent phosphorylation at the PKC site S368 at 24 hours creates specialized communication boundaries within the basal cells of the epidermis [78]. In addition our discussion has only considered a few Cx43 interacting proteins, but CASK and CADM1 directly interact with hypo-phosphorylated Cx43 one hour post-wounding in human keratinocytes to apparently regulate activation and migration [96]. So at this point, we are left with a number of questions related to the role of Cx43 in wound healing: i) What is the role of the increased gap junctional communication early after wounding?…”