Movatterモバイル変換

[0]ホーム
URL:

Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
Thehttps:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

NIH NLM Logo
Log inShow account info
Access keysNCBI HomepageMyNCBI HomepageMain ContentMain Navigation
pubmed logo
Advanced Clipboard
User Guide

Full text links

Atypon full text link Atypon Free PMC article
Full text links

Actions

Share

.2007 Nov 6;104(45):17867-72.
doi: 10.1073/pnas.0707722104. Epub 2007 Oct 30.

Ablation of sarcolipin enhances sarcoplasmic reticulum calcium transport and atrial contractility

Affiliations

Ablation of sarcolipin enhances sarcoplasmic reticulum calcium transport and atrial contractility

Gopal J Babu et al. Proc Natl Acad Sci U S A..

Abstract

Sarcolipin is a novel regulator of cardiac sarcoplasmic reticulum Ca2+ ATPase 2a (SERCA2a) and is expressed abundantly in atria. In this study we investigated the physiological significance of sarcolipin in the heart by generating a mouse model deficient for sarcolipin. The sarcolipin-null mice do not show any developmental abnormalities or any cardiac pathology. The absence of sarcolipin does not modify the expression level of other Ca2+ handling proteins, in particular phospholamban, and its phosphorylation status. Calcium uptake studies revealed that, in the atria, ablation of sarcolipin resulted in an increase in the affinity of the SERCA pump for Ca2+ and the maximum velocity of Ca2+ uptake rates. An important finding is that ablation of sarcolipin resulted in an increase in atrial Ca2+ transient amplitudes, and this resulted in enhanced atrial contractility. Furthermore, atria from sarcolipin-null mice showed a blunted response to isoproterenol stimulation, implicating sarcolipin as a mediator of beta-adrenergic responses in atria. Our study documented that sarcolipin is a key regulator of SERCA2a in atria. Importantly, our data demonstrate the existence of distinct modulators for the SERCA pump in the atria and ventricles.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Fig. 1.
Fig. 1.
Targeted disruption of SLN gene. (A) Schematic representation of the SLN gene knockout strategy. Exon 2 was replaced with a neomycin gene in reverse orientation. (B) RT-PCR analysis of SLN mRNA expression in the atria and ventricles of WT and homozygous SLN knockout (sln−/−) mice. (C) Western blotting analysis of SLN protein expression. SR-enriched microsomal fractions prepared from atria (A, 1 μg), and ventricles (V, 5 μg) of WT andsln−/− mice were separated on a 16% Tricine PAGE and immunoprobed with anti-rabbit SLN antibody.
Fig. 2.
Fig. 2.
Quantification of SR Ca2+ handling proteins. (A) Two different concentrations of total homogenates (4 and 8 μg for SERCA2a, PLB, and CSQ; 10 and 20 μg for DHPRα, RyR, and triadin) prepared from atrial and ventricular tissues of WT andsln−/− mice were separated on SDS/PAGE and immunoprobed with specific antibodies. (B) Total homogenates prepared fromsln−/− atria and ventricles were unboiled and analyzed for PLB monomers (PLBm) and pentamers (PLBp) by Western blot analysis. To determine the basal phosphorylation of PLB at serine-16 (PLB-S16) and threonine-17 (PLB-T17), snap-frozen samples were processed for protein extraction and immunoprobed with S16- or T17-specific PLB antibodies. Data shown are representative of three independent experiments.
Fig. 3.
Fig. 3.
Calcium uptake function insln−/− atria and ventricles. Ca2+ uptake assays were performed by using total homogenates from atria (A) and ventricles (B) of 24-week-old mice. For each atrial experiment, atria from four mice were pooled.n = 4 for each group. TheVmax of Ca2+ uptake was obtained at pCa 6.0.
Fig. 4.
Fig. 4.
Mechanical properties ofsln−/− atria. (A) Effect of extracellular Ca2+ and ISO on the isometric force generation in isolated left atria from WT andsln−/− mice. #, isometric force generation insln−/− atria (at 2 mM Ca2+) was significantly different from WT atria at all Ca2+ concentrations; *, isometric force generation in WT atria at 6 mM Ca2+ and ISO stimulation was significantly different from the basal contraction at 2 mM Ca2+ (P < 0.05). NS, not significant. Time taken for 50% relaxation (RT50) (B) and 90% relaxation (RT90) (C) was significantly faster in thesln−/− atria. *,P < 0.05 (significant difference between WT andsln−/− groups).n = 5.
Fig. 5.
Fig. 5.
Ca2+ transients in atrial and ventricular myocytes isolated from WT andsln−/− mice. (A) Representative examples of line-scan images in response to ISO stimulation showing kinetics of Ca2+i transients recorded from atrial and ventricular myocytes ofsln−/− mice compared with respective WT littermates. Sample records show a line-scan fluorescence images (Upper) and Ca2+i, measured asF/Fo (Lower). (B) Summary data for the amplitude of the total Ca2+ transient (A) obtained at baseline and after ISO stimulation for atrial and ventricular myocytes.n = 28 [WT A (−ISO)], 17 [sln−/− A (−ISO)], 20 [WT V (−ISO)], 19 [sln−/− V (−ISO)], 9 [WT A (+ISO)], 13 [sln−/− A (+ISO)], 17 [WT V (+ISO)], and 32 [sln−/− V (+ISO)] isolated from five to seven animals per group. (C) Summary data for the fast and slow time constants (τ1 and τ2) of the Ca2+ transient decay at baseline using two exponential functions.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Odermatt A, Taschner PE, Scherer SW, Beatty B, Khanna VK, Cornblath DR, Chaudhry V, Yee WC, Schrank B, Karpati G, et al. Genomics. 1997;45:541–553. - PubMed
    1. Minamisawa S, Wang Y, Chen J, Ishikawa Y, Chien KR, Matsuoka R. J Biol Chem. 2003;278:9570–9575. - PubMed
    1. Babu GJ, Zheng Z, Natarajan P, Wheeler D, Janssen PM, Periasamy M. Cardiovasc Res. 2005;65:177–186. - PubMed
    1. Babu GJ, Bhupathy P, Carnes CA, Billman GE, Periasamy M. J Mol Cell Cardiol. 2007;43:215–222. - PMC - PubMed
    1. Vangheluwe P, Schuermans M, Zador E, Waelkens E, Raeymaekers L, Wuytack F. Biochem J. 2005;389:151–159. - PMC - PubMed

Publication types

MeSH terms

Substances

Related information

Grants and funding

LinkOut - more resources

Full text links
Atypon full text link Atypon Free PMC article
Cite
Send To

NCBI Literature Resources

MeSHPMCBookshelfDisclaimer

The PubMed wordmark and PubMed logo are registered trademarks of the U.S. Department of Health and Human Services (HHS). Unauthorized use of these marks is strictly prohibited.

[8]ページ先頭
©2009-2025 Movatter.jp