A CLCA regulatory protein present in the chemosensory cilia of olfactory sensory neurons induces a Ca2+-activated Cl− current when transfected into HEK293

Abstract

BackgroundCLCA is a family of metalloproteases that regulate Ca2+-activated Cl− fluxes in epithelial tissues. In HEK293 cells, CLCA1 promotes membrane expression of an endogenous Anoctamin 1 (ANO1, also termed TMEM16A)-dependent Ca2+-activated Cl− current. Motif architecture similarity with CLCA2, 3 and 4 suggested that they have similar functions. We previously detected the isoform CLCA4L in rat olfactory sensory neurons, where Anoctamin 2 is the principal chemotransduction Ca2+-activated Cl− channel. We explored the possibility that this protein plays a role in odor transduction.ResultsWe cloned and expressed CLCA4L from rat olfactory epithelium in HEK293 cells. In the transfected HEK293 cells we measured a Cl−-selective Ca2+-activated current, blocked by niflumic acid, not present in the non-transfected cells. Thus, CLCA4L mimics the CLCA1 current on its ability to induce the ANO1-dependent Ca2+-activated Cl− current endogenous to these cells. By immunocytochemistry, a CLCA protein, presumably CLCA4L, was detected in the cilia of olfactory sensory neurons co-expressing with ANO2.ConclusionThese findings suggests that a CLCA isoform, namely CLCA4L, expressed in OSN cilia, might have a regulatory function over the ANO2-dependent Ca2+-activated Cl− channel involved in odor transduction.Electronic supplementary materialThe online version of this article (doi:10.1186/s12868-017-0379-7) contains supplementary material, which is available to authorized users.

Along with its favorable prognostic role, CLCA2 inhibits growth and metastasis of nasopharyngeal carcinoma cells via inhibition of FAK/ERK signaling

“…CLCA is a family of metalloproteases that regulates Ca 2+ -activated Cl − flux in epithelial tissue. In HEK293 cells, CLCA1 promotes membrane expression of an endogenous TMEM16A-dependent Ca 2+ -activated Cl − current [ 27 ]. Whole cell patch.…”

Assessing olfactory functions in patients with Barth syndrome

“…In vW syndrome, though, the gene encoding for the calcium-activated chloride channel, the TMEM16B [ 29 , 31 ], expressed in the olfactory epithelium and important for the signal transduction, may be mutated. Furthermore, the vW factor type A domain of the calcium-activated chloride channel regulators (CLCA) is necessary for the activity of some members of the family of TMEM16 channels [ 32 , 33 ]. This suggests that the vW factor itself may modulate elements of the olfactory signaling cascade ( i .…”

Calcium-Activated Cl- Channel: Insights on the Molecular Identity in Epithelial Tissues

“…Published research on CLCA1 and its interaction with TMEM16A is much more limited. However, all seem to point to an increase in overall membrane expression with a potential to increase the actual conductance of TMEM16A [42][43][44].…”

“…Another protein that has been implicated to interact with TMEM16A is the extracellular protease CLCA1 [42][43][44]. CLCA1 originally was thought to be a CaCC itself.…”