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Deletion of the sphingosine kinase-1 gene influences cell fate during hypoxia and glucose deprivation in adult mouse cardiomyocytes.
Cardiovasc Res 2007; 74(1):56-63CR

Abstract

OBJECTIVES

Activation of sphingosine kinase (SphK), which has two known isoforms, is responsible for the synthesis of sphingosine 1-phosphate (S1P), a cell survival factor. We tested the following hypotheses: 1] cardiac myocytes null for the SphK1 gene are more vulnerable to the stress of hypoxia+glucose deprivation; 2] the monoganglioside GM-1, which activates SphK via protein kinase C epsilon, is ineffective in SphK1-null myocytes; 3] S1P generated by SphK activation requires cellular export to be cardioprotective.

METHODS

We cultured adult mouse cardiac myocytes from wildtype and SphK1-null mice (deletion of exons 3-6) and measured cell viability by trypan blue exclusion.

RESULTS

In wildtype adult mouse cardiomyocytes subjected to 4 h of hypoxic stress+glucose deprivation, cell viability was significantly higher than in SphK1-null cardiomyocytes. SphK1-null cells also displayed more mitochondrial cytochrome C release. Cell death induced by hypoxia+glucose deprivation was substantially prevented by pretreatment with exogenous S1P in both wildtype and SphK1-null myocytes, but S1P was effective at a lower concentration in wildtype cells. Hence, the absence of the Sphk1 gene did not affect receptor coupling or downstream signal transduction. Pretreatment for 1 h with 1 microM of the monoganglioside GM-1 increased survival in wildtype cells, but not in SphK1-null myocytes. Thus, activation of SphK1 by GM-1 leads to cell survival. In wildtype cells, enhanced survival produced by GM-1 was abrogated by pretreatment either with 300 nM of the S1P(1) receptor-selective antagonist VPC23019 or with 100 ng/ml of pertussis toxin for 16 h before exposure to hypoxia+glucose deprivation.

CONCLUSION

As the effect of GM-1 is blocked both at the receptor and the G-protein (Gi) levels, we conclude that S1P generated by GM-1 treatment must be exported from the cell and acts in a paracrine or autocrine manner to couple with its cognate receptor.

Authors+Show Affiliations

Cardiology Section, Veterans Affairs Medical Center, University of California, San Francisco, CA 94121, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural

Language

eng

PubMed ID

17320845

Citation

Tao, Rong, et al. "Deletion of the Sphingosine Kinase-1 Gene Influences Cell Fate During Hypoxia and Glucose Deprivation in Adult Mouse Cardiomyocytes." Cardiovascular Research, vol. 74, no. 1, 2007, pp. 56-63.
Tao R, Zhang J, Vessey DA, et al. Deletion of the sphingosine kinase-1 gene influences cell fate during hypoxia and glucose deprivation in adult mouse cardiomyocytes. Cardiovasc Res. 2007;74(1):56-63.
Tao, R., Zhang, J., Vessey, D. A., Honbo, N., & Karliner, J. S. (2007). Deletion of the sphingosine kinase-1 gene influences cell fate during hypoxia and glucose deprivation in adult mouse cardiomyocytes. Cardiovascular Research, 74(1), pp. 56-63.
Tao R, et al. Deletion of the Sphingosine Kinase-1 Gene Influences Cell Fate During Hypoxia and Glucose Deprivation in Adult Mouse Cardiomyocytes. Cardiovasc Res. 2007 Apr 1;74(1):56-63. PubMed PMID: 17320845.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Deletion of the sphingosine kinase-1 gene influences cell fate during hypoxia and glucose deprivation in adult mouse cardiomyocytes. AU - Tao,Rong, AU - Zhang,Jianqing, AU - Vessey,Donald A, AU - Honbo,Norman, AU - Karliner,Joel S, Y1 - 2007/01/23/ PY - 2006/09/11/received PY - 2006/12/22/revised PY - 2007/01/16/accepted PY - 2007/2/27/pubmed PY - 2007/6/22/medline PY - 2007/2/27/entrez SP - 56 EP - 63 JF - Cardiovascular research JO - Cardiovasc. Res. VL - 74 IS - 1 N2 - OBJECTIVES: Activation of sphingosine kinase (SphK), which has two known isoforms, is responsible for the synthesis of sphingosine 1-phosphate (S1P), a cell survival factor. We tested the following hypotheses: 1] cardiac myocytes null for the SphK1 gene are more vulnerable to the stress of hypoxia+glucose deprivation; 2] the monoganglioside GM-1, which activates SphK via protein kinase C epsilon, is ineffective in SphK1-null myocytes; 3] S1P generated by SphK activation requires cellular export to be cardioprotective. METHODS: We cultured adult mouse cardiac myocytes from wildtype and SphK1-null mice (deletion of exons 3-6) and measured cell viability by trypan blue exclusion. RESULTS: In wildtype adult mouse cardiomyocytes subjected to 4 h of hypoxic stress+glucose deprivation, cell viability was significantly higher than in SphK1-null cardiomyocytes. SphK1-null cells also displayed more mitochondrial cytochrome C release. Cell death induced by hypoxia+glucose deprivation was substantially prevented by pretreatment with exogenous S1P in both wildtype and SphK1-null myocytes, but S1P was effective at a lower concentration in wildtype cells. Hence, the absence of the Sphk1 gene did not affect receptor coupling or downstream signal transduction. Pretreatment for 1 h with 1 microM of the monoganglioside GM-1 increased survival in wildtype cells, but not in SphK1-null myocytes. Thus, activation of SphK1 by GM-1 leads to cell survival. In wildtype cells, enhanced survival produced by GM-1 was abrogated by pretreatment either with 300 nM of the S1P(1) receptor-selective antagonist VPC23019 or with 100 ng/ml of pertussis toxin for 16 h before exposure to hypoxia+glucose deprivation. CONCLUSION: As the effect of GM-1 is blocked both at the receptor and the G-protein (Gi) levels, we conclude that S1P generated by GM-1 treatment must be exported from the cell and acts in a paracrine or autocrine manner to couple with its cognate receptor. SN - 0008-6363 UR - https://www.unboundmedicine.com/medline/citation/17320845/Deletion_of_the_sphingosine_kinase_1_gene_influences_cell_fate_during_hypoxia_and_glucose_deprivation_in_adult_mouse_cardiomyocytes_ L2 - https://academic.oup.com/cardiovascres/article-lookup/doi/10.1016/j.cardiores.2007.01.015 DB - PRIME DP - Unbound Medicine ER -