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Activation of the Calcium Sensing Receptor potentially inhibits Kv1.5 channel activity
Author(s) -
Ayon Ramon J,
Tang Haiyang,
Yee Allison M,
Dash Swetaleena,
EkVitorin Jose F,
Makino Ayako,
Yuan Jason X.J.
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.1281.10
Subject(s) - hek 293 cells , g protein coupled receptor , microbiology and biotechnology , transfection , calcium sensing receptor , chemistry , receptor , tyrosine kinase , extracellular , biophysics , calcium , biochemistry , biology , parathyroid hormone , organic chemistry , gene
The Calcium sensing receptor (CaSR) is class of G protein coupled receptors (GPCR) that can be activated by extracellular Ca 2+ and Mg 2+ . Activation of CaSR can stimulate the phospholipase C (PLC) signaling pathway that leads to synthesis of inositol 1,4,5 triphosphate (IP 3 ) and diacylglycerol (DAG). Voltage‐gated potassium (Kv) channels activity is essential for establishing resting membrane potential in a variety of cell types including pulmonary artery smooth muscle cells (PASMC). Indeed, stimulation or inhibition of K + channels can easily determine cell fate, as K + channel activity is associated with cell proliferation, survival and apoptosis. It has been reported that some K + channel classes are regulated by GPCRs. For example, Kv1.2, and members of the two‐pore domain K + channel family (TASK‐1 and TASK‐3) were shown to be inhibited by GPCR activation. Interestingly, Kv1.5 channel activity can also be suppressed by stimulation of GPCR via the Src tyrosine kinase pathway. However there are no reports to date that have shown any functional interaction between CaSR and Kv1.5. In this present study, we examined the effects of CaSR activation on Kv1.5 channel activity by transfection of KCNA5, which encodes for the Kv1.5 pore‐forming α subunit, alone or cotransfection of KCNA5/CaSR in HEK293 cells. Overexpression of KCNA5 and CaSR/KCNA5 in HEK293 cells were confirmed by Western blot and Immunofluorescence. Kv1.5 current amplitude (I Kv1.5 ) was significantly attenuated by 1.8 mM external Ca 2+ in cells transfected with both CaSR/KCNA5 but not in cells transfected with KCNA5 alone. To determine whether this Ca 2+ induced decrease of I Kv1.5 was due to activation of PLC‐DAG‐IP 3 signaling cascade we used the PLC inhibitor U‐73122. Preliminary data showed that 10uM U‐73122 was capable of antagonizing the external Ca 2+ induced decrease in I Kv1.5 . This would suggests that activation of CaSR by way of external Ca 2+ is capable of inhibiting Kv1.5 channel activity via PLC signaling pathway Support or Funding Information Research supported by NIH Grants (HL115014, HL066012 and HL098053).