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Deletion of CXCR4 in cardiomyocytes exacerbates cardiac dysfunction following isoproterenol administration.

Wang ER, Jarrah AA, Benard L, Chen J, Schwarzkopf M, Hadri L, Tarzami ST - Gene Ther. (2014)

Bottom Line: CXCR4 ablation increased susceptibility to isoproterenol-induced heart failure, by upregulating apoptotic markers and reducing mitochondrial function; cardiac function decreases whereas fibrosis increases.In addition, CXCR4 expression was rescued with the use of cardiotropic adeno-associated viral-9 vectors.Our results represent the first evidence that SDF-1/CXCR4 signaling mediates acute cardioprotection through modulating beta-adrenergic receptor signaling in vivo.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, Division of Cardiovascular Research Center, Mount Sinai School of Medicine, New York, NY, USA.

ABSTRACT
Altered alpha- and beta-adrenergic receptor signaling is associated with cardiac hypertrophy and failure. Stromal cell-derived factor-1α (SDF-1α) and its cognate receptor CXCR4 have been reported to mediate cardioprotection after injury through the mobilization of stem cells into injured tissue. However, little is known regarding whether SDF-1/CXCR4 induces acute protection following pathological hypertrophy and if so, by what molecular mechanism. We have previously reported that CXCR4 physically interacts with the beta-2 adrenergic receptor and modulates its downstream signaling. Here we have shown that CXCR4 expression prevents beta-adrenergic receptor-induced hypertrophy. Cardiac beta-adrenergic receptors were stimulated with the implantation of a subcutaneous osmotic pump administrating isoproterenol and CXCR4 expression was selectively abrogated in cardiomyocytes using Cre-loxP-mediated gene recombination. CXCR4 knockout mice showed worsened fractional shortening and ejection fraction. CXCR4 ablation increased susceptibility to isoproterenol-induced heart failure, by upregulating apoptotic markers and reducing mitochondrial function; cardiac function decreases whereas fibrosis increases. In addition, CXCR4 expression was rescued with the use of cardiotropic adeno-associated viral-9 vectors. CXCR4 gene transfer reduced cardiac apoptotic signaling, improved mitochondrial function and resulted in a recovered cardiac function. Our results represent the first evidence that SDF-1/CXCR4 signaling mediates acute cardioprotection through modulating beta-adrenergic receptor signaling in vivo.

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Transcriptional profile suggests upregulation of apoptotic markers. (a) RNA was isolated from whole ventricular myocardium and the expression of 84 genes were tested using qRT-PCR arrays in which fold changes (x axis) in gene expression of AAV9.CXCR4-rescued knockouts are shown compared to knockouts injected with AAV9.lacZ (n=3 per group). (b) mRNA expression of GSK3-activated pro-apoptotic factors; P53 and Bax (quantified via qRT-PCR) was shown in upper panel (n=3) and representative Western blots of P53 and Bax protein expression from four animals per group is shown in the lower panel (*= p<0.05). (c) Densitometric analysis for GSK3β phosphorylation/total-GSK3β is shown (*= p<0.05) and a representative Western blot of GSK3β phosphorylation on Ser9 is depicted. Western blots were performed on lysates prepared from whole ventricular tissue, and quantification was performed using four animals per group.
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Figure 5: Transcriptional profile suggests upregulation of apoptotic markers. (a) RNA was isolated from whole ventricular myocardium and the expression of 84 genes were tested using qRT-PCR arrays in which fold changes (x axis) in gene expression of AAV9.CXCR4-rescued knockouts are shown compared to knockouts injected with AAV9.lacZ (n=3 per group). (b) mRNA expression of GSK3-activated pro-apoptotic factors; P53 and Bax (quantified via qRT-PCR) was shown in upper panel (n=3) and representative Western blots of P53 and Bax protein expression from four animals per group is shown in the lower panel (*= p<0.05). (c) Densitometric analysis for GSK3β phosphorylation/total-GSK3β is shown (*= p<0.05) and a representative Western blot of GSK3β phosphorylation on Ser9 is depicted. Western blots were performed on lysates prepared from whole ventricular tissue, and quantification was performed using four animals per group.

Mentions: Our next step was to assess the possible mechanisms that confer protection and are modulated by CXCR4. RNA was isolated from whole ventricular myocardium and specific mRNA levels were quantified. Using a commercial PCR array, we identified genes that were either upregulated or downregulated in AAV9.CXCR4-rescued mice as compared to CXCR4-KO mice post isoproterenol treatment. Interestingly, many of these genes were associated with cell death pathways (Figure 5a). Our data demonstrates significant upregulation of p53 (tumor suppressor gene) and Bax (Bcl-2-associated X protein) in the CXCR4-KO group, whereas AAV9.CXCR4-gene therapy prevented upregulation and reduced mRNA levels and their protein expression significantly (Figure 5b). p53 and Bax are both pro-apoptotic genes that can be regulated by the glycogen synthase kinase 3 (GSK3) signaling pathway.34


Deletion of CXCR4 in cardiomyocytes exacerbates cardiac dysfunction following isoproterenol administration.

Wang ER, Jarrah AA, Benard L, Chen J, Schwarzkopf M, Hadri L, Tarzami ST - Gene Ther. (2014)

Transcriptional profile suggests upregulation of apoptotic markers. (a) RNA was isolated from whole ventricular myocardium and the expression of 84 genes were tested using qRT-PCR arrays in which fold changes (x axis) in gene expression of AAV9.CXCR4-rescued knockouts are shown compared to knockouts injected with AAV9.lacZ (n=3 per group). (b) mRNA expression of GSK3-activated pro-apoptotic factors; P53 and Bax (quantified via qRT-PCR) was shown in upper panel (n=3) and representative Western blots of P53 and Bax protein expression from four animals per group is shown in the lower panel (*= p<0.05). (c) Densitometric analysis for GSK3β phosphorylation/total-GSK3β is shown (*= p<0.05) and a representative Western blot of GSK3β phosphorylation on Ser9 is depicted. Western blots were performed on lysates prepared from whole ventricular tissue, and quantification was performed using four animals per group.
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Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4016112&req=5

Figure 5: Transcriptional profile suggests upregulation of apoptotic markers. (a) RNA was isolated from whole ventricular myocardium and the expression of 84 genes were tested using qRT-PCR arrays in which fold changes (x axis) in gene expression of AAV9.CXCR4-rescued knockouts are shown compared to knockouts injected with AAV9.lacZ (n=3 per group). (b) mRNA expression of GSK3-activated pro-apoptotic factors; P53 and Bax (quantified via qRT-PCR) was shown in upper panel (n=3) and representative Western blots of P53 and Bax protein expression from four animals per group is shown in the lower panel (*= p<0.05). (c) Densitometric analysis for GSK3β phosphorylation/total-GSK3β is shown (*= p<0.05) and a representative Western blot of GSK3β phosphorylation on Ser9 is depicted. Western blots were performed on lysates prepared from whole ventricular tissue, and quantification was performed using four animals per group.
Mentions: Our next step was to assess the possible mechanisms that confer protection and are modulated by CXCR4. RNA was isolated from whole ventricular myocardium and specific mRNA levels were quantified. Using a commercial PCR array, we identified genes that were either upregulated or downregulated in AAV9.CXCR4-rescued mice as compared to CXCR4-KO mice post isoproterenol treatment. Interestingly, many of these genes were associated with cell death pathways (Figure 5a). Our data demonstrates significant upregulation of p53 (tumor suppressor gene) and Bax (Bcl-2-associated X protein) in the CXCR4-KO group, whereas AAV9.CXCR4-gene therapy prevented upregulation and reduced mRNA levels and their protein expression significantly (Figure 5b). p53 and Bax are both pro-apoptotic genes that can be regulated by the glycogen synthase kinase 3 (GSK3) signaling pathway.34

Bottom Line: CXCR4 ablation increased susceptibility to isoproterenol-induced heart failure, by upregulating apoptotic markers and reducing mitochondrial function; cardiac function decreases whereas fibrosis increases.In addition, CXCR4 expression was rescued with the use of cardiotropic adeno-associated viral-9 vectors.Our results represent the first evidence that SDF-1/CXCR4 signaling mediates acute cardioprotection through modulating beta-adrenergic receptor signaling in vivo.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, Division of Cardiovascular Research Center, Mount Sinai School of Medicine, New York, NY, USA.

ABSTRACT
Altered alpha- and beta-adrenergic receptor signaling is associated with cardiac hypertrophy and failure. Stromal cell-derived factor-1α (SDF-1α) and its cognate receptor CXCR4 have been reported to mediate cardioprotection after injury through the mobilization of stem cells into injured tissue. However, little is known regarding whether SDF-1/CXCR4 induces acute protection following pathological hypertrophy and if so, by what molecular mechanism. We have previously reported that CXCR4 physically interacts with the beta-2 adrenergic receptor and modulates its downstream signaling. Here we have shown that CXCR4 expression prevents beta-adrenergic receptor-induced hypertrophy. Cardiac beta-adrenergic receptors were stimulated with the implantation of a subcutaneous osmotic pump administrating isoproterenol and CXCR4 expression was selectively abrogated in cardiomyocytes using Cre-loxP-mediated gene recombination. CXCR4 knockout mice showed worsened fractional shortening and ejection fraction. CXCR4 ablation increased susceptibility to isoproterenol-induced heart failure, by upregulating apoptotic markers and reducing mitochondrial function; cardiac function decreases whereas fibrosis increases. In addition, CXCR4 expression was rescued with the use of cardiotropic adeno-associated viral-9 vectors. CXCR4 gene transfer reduced cardiac apoptotic signaling, improved mitochondrial function and resulted in a recovered cardiac function. Our results represent the first evidence that SDF-1/CXCR4 signaling mediates acute cardioprotection through modulating beta-adrenergic receptor signaling in vivo.

Show MeSH
Related in: MedlinePlus