Universität zu Köln

Dizayee, Sara, Kaestner, Sonja, Kuck, Fabian, Hein, Peter ORCID: 0000-0002-5899-3979, Klein, Christoph, Piekorz, Roland P., Meszaros, Janos, Matthes, Jan ORCID: 0000-0003-2754-1555, Nuernberg, Bernd and Herzig, Stefan (2011). G alpha(i2)- and G alpha(i3)-Specific Regulation of Voltage-Dependent L-Type Calcium Channels in Cardiomyocytes. PLoS One, 6 (9). SAN FRANCISCO: PUBLIC LIBRARY SCIENCE. ISSN 1932-6203

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Abstract

Background: Two pertussis toxin sensitive G(i) proteins, G(i2) and G(i3), are expressed in cardiomyocytes and upregulated in heart failure. It has been proposed that the highly homologous G(i) isoforms are functionally distinct. To test for isoform-specific functions of G(i) proteins, we examined their role in the regulation of cardiac L-type voltage-dependent calcium channels (L-VDCC). Methods: Ventricular tissues and isolated myocytes were obtained from mice with targeted deletion of either G alpha(i2) (G alpha(-/-)(i2)) or G alpha(i3) (G alpha(-/-)(i3)). mRNA levels of G alpha(i/o) isoforms and L-VDCC subunits were quantified by real-time PCR. G alpha(i) and Ca-v alpha(1) protein levels as well as protein kinase B/Akt and extracellular signal-regulated kinases 1/2 (ERK1/2) phosphorylation levels were assessed by immunoblot analysis. L-VDCC function was assessed by whole-cell and single-channel current recordings. Results: In cardiac tissue from G alpha(-/-)(i2) mice, G alpha(i3) mRNA and protein expression was upregulated to 187 +/- 21% and 567 +/- 59%, respectively. In G alpha(-/-)(i3) mouse hearts, G alpha(i2) mRNA (127 +/- 5%) and protein (131 +/- 10%) levels were slightly enhanced. Interestingly, L-VDCC current density in cardiomyocytes from G alpha(-/-)(i2) mice was lowered (-7.9 +/- 0.6 pA/pF, n = 11, p<0.05) compared to wild-type cells (-10.7 +/- 0.5 pA/pF, n = 22), whereas it was increased in myocytes from G alpha(-/-)(i3) mice (-14.3 +/- 0.8 pA/pF, n = 14, p<0.05). Steady-state inactivation was shifted to negative potentials, and recovery kinetics slowed in the absence of G alpha(i2) (but not of G alpha(i3)) and following treatment with pertussis toxin in G alpha(-/-)(i3). The pore forming Ca-v alpha(1) protein level was unchanged in all mouse models analyzed, similar to mRNA levels of Ca-v alpha(1) and Ca-v beta(2) subunits. Interestingly, at the cellular signalling level, phosphorylation assays revealed abolished carbachol-triggered activation of ERK1/2 in mice lacking G alpha(i2). Conclusion: Our data provide novel evidence for an isoform-specific modulation of L-VDCC by G alpha(i) proteins. In particular, loss of G alpha(i2) is reflected by alterations in channel kinetics and likely involves an impairment of the ERK1/2 signalling pathway.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Dizayee, Sara UNSPECIFIED UNSPECIFIED UNSPECIFIED Kaestner, Sonja UNSPECIFIED UNSPECIFIED UNSPECIFIED Kuck, Fabian UNSPECIFIED UNSPECIFIED UNSPECIFIED Hein, Peter UNSPECIFIED orcid.org/0000-0002-5899-3979 UNSPECIFIED Klein, Christoph UNSPECIFIED UNSPECIFIED UNSPECIFIED Piekorz, Roland P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Meszaros, Janos UNSPECIFIED UNSPECIFIED UNSPECIFIED Matthes, Jan UNSPECIFIED orcid.org/0000-0003-2754-1555 UNSPECIFIED Nuernberg, Bernd UNSPECIFIED UNSPECIFIED UNSPECIFIED Herzig, Stefan UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-488856
DOI:	10.1371/journal.pone.0024979
Journal or Publication Title:	PLoS One
Volume:	6
Number:	9
Date:	2011
Publisher:	PUBLIC LIBRARY SCIENCE
Place of Publication:	SAN FRANCISCO
ISSN:	1932-6203
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language G-PROTEIN G(I3); HEART-FAILURE; CARDIAC MYOCYTES; CA2+ CHANNELS; VENTRICULAR MYOCYTES; BETA-SUBUNITS; GENE KNOCKOUT; CELL-DEATH; INHIBITION; RECEPTOR Multiple languages Multidisciplinary Sciences Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/48885