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A Drosophila ABC transporter regulates lifespan.

Huang H, Lu-Bo Y, Haddad GG - PLoS Genet. (2014)

Bottom Line: MRP4 (multidrug resistance-associated protein 4) is a member of the MRP/ABCC subfamily of ATP-binding cassette (ABC) transporters that are essential for many cellular processes requiring the transport of substrates across cell membranes.By genetic manipulations, we demonstrate that dMRP4 is required for JNK (c-Jun NH2-terminal kinase) activation during paraquat challenge and for basal transcription of some JNK target genes under normal condition.We show that impaired JNK signaling is an important cause for major defects associated with dMRP4 mutations, suggesting that dMRP4 regulates lifespan by modulating the expression of a set of genes related to both oxidative resistance and aging, at least in part, through JNK signaling.

View Article: PubMed Central - PubMed

Affiliation: Department of Pediatrics (Division of Respiratory Medicine), University of California San Diego, La Jolla, California, United States of America.

ABSTRACT
MRP4 (multidrug resistance-associated protein 4) is a member of the MRP/ABCC subfamily of ATP-binding cassette (ABC) transporters that are essential for many cellular processes requiring the transport of substrates across cell membranes. Although MRP4 has been implicated as a detoxification protein by transport of structurally diverse endogenous and xenobiotic compounds, including antivirus and anticancer drugs, that usually induce oxidative stress in cells, its in vivo biological function remains unknown. In this study, we investigate the biological functions of a Drosophila homolog of human MRP4, dMRP4. We show that dMRP4 expression is elevated in response to oxidative stress (paraquat, hydrogen peroxide and hyperoxia) in Drosophila. Flies lacking dMRP4 have a shortened lifespan under both oxidative and normal conditions. Overexpression of dMRP4, on the other hand, is sufficient to increase oxidative stress resistance and extend lifespan. By genetic manipulations, we demonstrate that dMRP4 is required for JNK (c-Jun NH2-terminal kinase) activation during paraquat challenge and for basal transcription of some JNK target genes under normal condition. We show that impaired JNK signaling is an important cause for major defects associated with dMRP4 mutations, suggesting that dMRP4 regulates lifespan by modulating the expression of a set of genes related to both oxidative resistance and aging, at least in part, through JNK signaling.

No MeSH data available.


Related in: MedlinePlus

dMRP4 is required for JNK-mediated gene expression under oxidative stress.qt-PCR analysis of mRNA isolated from WT flies (w1118) after exposed to 10 mM paraquat (PQ) for indicated time points. (A–D) Relative mRNA levels were compared between w1118 and dMRP4 to the respective controls (no paraquat feeding) where the basal values were set at 1.0. (E) Relative mRNA levels of dMRP4 from flies carrying actGS-BskDN were compared between RU486 feeding (+RU, 150 ug/ml) and non-feeding groups [75]. (F) Relative mRNA levels of dMRP4 from flies carrying actGS-HepAct were compared between RU486 feeding (+RU, 150 ug/ml) and non-feeding groups [75]. puc expression served as a marker for JNK activity in response to paraquat. Data was presented as means ± SD from 3–5 independent experiments. Student's t-test: * p<0.05, ** p<0.01, *** p<0.001. ns: No significance (p>0.05).
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pgen-1004844-g003: dMRP4 is required for JNK-mediated gene expression under oxidative stress.qt-PCR analysis of mRNA isolated from WT flies (w1118) after exposed to 10 mM paraquat (PQ) for indicated time points. (A–D) Relative mRNA levels were compared between w1118 and dMRP4 to the respective controls (no paraquat feeding) where the basal values were set at 1.0. (E) Relative mRNA levels of dMRP4 from flies carrying actGS-BskDN were compared between RU486 feeding (+RU, 150 ug/ml) and non-feeding groups [75]. (F) Relative mRNA levels of dMRP4 from flies carrying actGS-HepAct were compared between RU486 feeding (+RU, 150 ug/ml) and non-feeding groups [75]. puc expression served as a marker for JNK activity in response to paraquat. Data was presented as means ± SD from 3–5 independent experiments. Student's t-test: * p<0.05, ** p<0.01, *** p<0.001. ns: No significance (p>0.05).

Mentions: Oxidative stress is known to activate a protective program involving induction of a number of stress-responsive genes in cells [3], [6], [35], [36]. JNK signaling is activated in response to oxidative stress and is a major genetic factor in control of oxidative stress tolerance and aging process [3], [6], [35], [36], [37]. Since puc (a phosphatase inhibitor of JNK) is often used as a marker for activation of the JNK pathway [3], [6], [35], [36], [38], we tested whether there were any differential expression changes of JNK signaling by examining puc induction in dMRP4 mutant flies fed with paraquat. Compared to the pattern in wild-type flies, puc expression was completely diminished in dMRP4 mutant flies under oxidative stress (Fig. 3A). To further evaluate whether dMRP4 might play a general role in JNK signaling, induction of other JNK-mediated marker genes, such as gstD1[6], hsp68 and Jafrac1, was also examined. Although expression of all these marker genes was induced in wild-type flies after paraquat feeding, their induction, with exception for gstD1, was significantly reduced in the dMRP4 mutant flies (Fig. 3C–D), indicating that activation of JNK signaling by oxidative stress requires a wild-type dMRP4 function. Because flies deficient for JNK signaling become more susceptible to stress [6], a phenotype resembling what we have observed with flies deficient for dMRP4, impairment of JNK signaling in dMRP4 mutants may be an important cause for increased lethality when animals face oxidative insults. There was also a possibility that dMRP4 itself may be a component of the JNK pathway.


A Drosophila ABC transporter regulates lifespan.

Huang H, Lu-Bo Y, Haddad GG - PLoS Genet. (2014)

dMRP4 is required for JNK-mediated gene expression under oxidative stress.qt-PCR analysis of mRNA isolated from WT flies (w1118) after exposed to 10 mM paraquat (PQ) for indicated time points. (A–D) Relative mRNA levels were compared between w1118 and dMRP4 to the respective controls (no paraquat feeding) where the basal values were set at 1.0. (E) Relative mRNA levels of dMRP4 from flies carrying actGS-BskDN were compared between RU486 feeding (+RU, 150 ug/ml) and non-feeding groups [75]. (F) Relative mRNA levels of dMRP4 from flies carrying actGS-HepAct were compared between RU486 feeding (+RU, 150 ug/ml) and non-feeding groups [75]. puc expression served as a marker for JNK activity in response to paraquat. Data was presented as means ± SD from 3–5 independent experiments. Student's t-test: * p<0.05, ** p<0.01, *** p<0.001. ns: No significance (p>0.05).
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4256198&req=5

pgen-1004844-g003: dMRP4 is required for JNK-mediated gene expression under oxidative stress.qt-PCR analysis of mRNA isolated from WT flies (w1118) after exposed to 10 mM paraquat (PQ) for indicated time points. (A–D) Relative mRNA levels were compared between w1118 and dMRP4 to the respective controls (no paraquat feeding) where the basal values were set at 1.0. (E) Relative mRNA levels of dMRP4 from flies carrying actGS-BskDN were compared between RU486 feeding (+RU, 150 ug/ml) and non-feeding groups [75]. (F) Relative mRNA levels of dMRP4 from flies carrying actGS-HepAct were compared between RU486 feeding (+RU, 150 ug/ml) and non-feeding groups [75]. puc expression served as a marker for JNK activity in response to paraquat. Data was presented as means ± SD from 3–5 independent experiments. Student's t-test: * p<0.05, ** p<0.01, *** p<0.001. ns: No significance (p>0.05).
Mentions: Oxidative stress is known to activate a protective program involving induction of a number of stress-responsive genes in cells [3], [6], [35], [36]. JNK signaling is activated in response to oxidative stress and is a major genetic factor in control of oxidative stress tolerance and aging process [3], [6], [35], [36], [37]. Since puc (a phosphatase inhibitor of JNK) is often used as a marker for activation of the JNK pathway [3], [6], [35], [36], [38], we tested whether there were any differential expression changes of JNK signaling by examining puc induction in dMRP4 mutant flies fed with paraquat. Compared to the pattern in wild-type flies, puc expression was completely diminished in dMRP4 mutant flies under oxidative stress (Fig. 3A). To further evaluate whether dMRP4 might play a general role in JNK signaling, induction of other JNK-mediated marker genes, such as gstD1[6], hsp68 and Jafrac1, was also examined. Although expression of all these marker genes was induced in wild-type flies after paraquat feeding, their induction, with exception for gstD1, was significantly reduced in the dMRP4 mutant flies (Fig. 3C–D), indicating that activation of JNK signaling by oxidative stress requires a wild-type dMRP4 function. Because flies deficient for JNK signaling become more susceptible to stress [6], a phenotype resembling what we have observed with flies deficient for dMRP4, impairment of JNK signaling in dMRP4 mutants may be an important cause for increased lethality when animals face oxidative insults. There was also a possibility that dMRP4 itself may be a component of the JNK pathway.

Bottom Line: MRP4 (multidrug resistance-associated protein 4) is a member of the MRP/ABCC subfamily of ATP-binding cassette (ABC) transporters that are essential for many cellular processes requiring the transport of substrates across cell membranes.By genetic manipulations, we demonstrate that dMRP4 is required for JNK (c-Jun NH2-terminal kinase) activation during paraquat challenge and for basal transcription of some JNK target genes under normal condition.We show that impaired JNK signaling is an important cause for major defects associated with dMRP4 mutations, suggesting that dMRP4 regulates lifespan by modulating the expression of a set of genes related to both oxidative resistance and aging, at least in part, through JNK signaling.

View Article: PubMed Central - PubMed

Affiliation: Department of Pediatrics (Division of Respiratory Medicine), University of California San Diego, La Jolla, California, United States of America.

ABSTRACT
MRP4 (multidrug resistance-associated protein 4) is a member of the MRP/ABCC subfamily of ATP-binding cassette (ABC) transporters that are essential for many cellular processes requiring the transport of substrates across cell membranes. Although MRP4 has been implicated as a detoxification protein by transport of structurally diverse endogenous and xenobiotic compounds, including antivirus and anticancer drugs, that usually induce oxidative stress in cells, its in vivo biological function remains unknown. In this study, we investigate the biological functions of a Drosophila homolog of human MRP4, dMRP4. We show that dMRP4 expression is elevated in response to oxidative stress (paraquat, hydrogen peroxide and hyperoxia) in Drosophila. Flies lacking dMRP4 have a shortened lifespan under both oxidative and normal conditions. Overexpression of dMRP4, on the other hand, is sufficient to increase oxidative stress resistance and extend lifespan. By genetic manipulations, we demonstrate that dMRP4 is required for JNK (c-Jun NH2-terminal kinase) activation during paraquat challenge and for basal transcription of some JNK target genes under normal condition. We show that impaired JNK signaling is an important cause for major defects associated with dMRP4 mutations, suggesting that dMRP4 regulates lifespan by modulating the expression of a set of genes related to both oxidative resistance and aging, at least in part, through JNK signaling.

No MeSH data available.


Related in: MedlinePlus