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Overexpression of GRK5 prevents angiotensin II blockade of peak potassium currents and normalizes Kv4.3 expression in neurons (874.12)
Author(s) -
Becker Bryan,
Haack Karla,
Zucker Irving
Publication year - 2014
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.28.1_supplement.874.12
Subject(s) - angiotensin ii , medicine , endocrinology , chemistry , gene knockdown , potassium channel , receptor , kinase , biology , apoptosis , biochemistry
The Angiotensin II (Ang II)‐ Ang II type 1 Receptor (AT1R) signaling axis has been shown to decrease peak potassium (K + ) currents (Ito) and Kv4.3 (a voltage gated K + channel subunit) expression. G protein coupled receptor kinase 5 (GRK5) phosphorylates AT1R and desensitizes it. We hypothesized that GRK5 overexpression can blunt the Ang II‐mediated decrease in Ito and normalize Kv4.3 expression in CATH.a neurons. Neurons were transfected with either mock or pcDNA3‐GRK5 plasmid and stimulated with either vehicle or 100 nM Ang II for 4 hours. Neurons treated with Ang II exhibited decreased Ito relative to control (95.8 ± 16.6 vs 149.4 ± 18.9 pA/pF; p<0.05). This effect was attenuated by GRK5 overexpression (179.0 ± 34.5 pA/pF). Time to peak current was significantly increased in AngII neurons relative to control (45.5 ± 14.5 vs 21.3 ± 5.1 ms; p<0.05). GRK5 overexpression normalized this response (21.4 ± 5.6 ms). Western blot analyses indicated that GRK5 overexpression significantly increased basal Kv4.3 levels compared to sham (1.5 ± 0.3 vs 1.0 ± 0.1) but did not prevent the Ang II‐mediated decrease in Kv4.3 (0.5 ± 0.2 vs 0.7 ± 0.2). siRNA knockdown of GRK5 decreased basal Kv4.3 levels compared to sham (0.3 ± 0.1 vs 1.0 ± 0.1) and Ang II did not decrease Kv4.3 expression further. These data suggest that GRK5 overexpression blunts the Ang II‐mediated decrease in Ito. GRK5 may contribute to the regulation of Kv4.3. Grant Funding Source : Supported by NIH grant P01‐HL62222