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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 regulates expression of some stress- and aging-related genes.(A) dMRP4 was required for basal expression of several stress- and aging-related genes. The mRNA levels of these genes were compared between w1118 and dMRP4 mutant (dMRP4M2/M2) by qt-PCR analysis. (B) Elevated expression of dMRP4 increased the basal expression of stress- and aging-related genes. The mRNA levels of these genes were compared between control Gal4 (da/+) and dMRP4 overexpression (da>dMRP4) by qt-PCR analysis. 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-g006: dMRP4 regulates expression of some stress- and aging-related genes.(A) dMRP4 was required for basal expression of several stress- and aging-related genes. The mRNA levels of these genes were compared between w1118 and dMRP4 mutant (dMRP4M2/M2) by qt-PCR analysis. (B) Elevated expression of dMRP4 increased the basal expression of stress- and aging-related genes. The mRNA levels of these genes were compared between control Gal4 (da/+) and dMRP4 overexpression (da>dMRP4) by qt-PCR analysis. 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: In order to learn the molecular mechanism by which dMRP4 regulates lifespan, we selectively studied transcription profiling of several genes whose expression changes have been linked to both aging and stress [1]. Among five hsp (heat shock protein) genes examined, expression of three genes, hsp68, hsp70 and l(2)efl (lethal (2) essential for life, a small hsp gene) was severely down-regulated in dMRP4 mutant flies (Fig. 6A), while they were significantly up-regulated when dMRP4 was overexpressed (Fig. 6B). Overexpression of dMRP4 was also sufficient to increase expression of other two hsp genes, hsp22 and hsp83 (Fig. 6B). Since l(2)efl is a known target of dFOXO (Drosophila forkhead transcription factor) in lifespan regulation [52], it raised the possibility that dMRP4 might regulate expression of other dFOXO-dependent genes. Indeed, expression of the dFOXO target gene thor, which encodes 4E-BP (eIF4E binding protein), was also greatly enhanced when dMRP4 was overexpressed. Since both thor and hsp68 are target genes of JNK signaling [6], [52], we further examined expression patterns of several other JNK targets (Fig. 3A–D). Like hsp68, basal expression of puc and gstD1 was down-regulated in dMRP4 mutant flies and was up-regulated with dMRP4 overexpression (Fig. 6A–B). Furthermore, basal expression of Jafrac1 was increased when dMRP4 was overexpressed, even though its expression was not affected by dMRP4 mutation under normal condition. Thus, in addition to regulating the JNK-dependent gene expression under oxidative stress, dMRP4 also regulates the basal transcription of such genes under normal conditions.


A Drosophila ABC transporter regulates lifespan.

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

dMRP4 regulates expression of some stress- and aging-related genes.(A) dMRP4 was required for basal expression of several stress- and aging-related genes. The mRNA levels of these genes were compared between w1118 and dMRP4 mutant (dMRP4M2/M2) by qt-PCR analysis. (B) Elevated expression of dMRP4 increased the basal expression of stress- and aging-related genes. The mRNA levels of these genes were compared between control Gal4 (da/+) and dMRP4 overexpression (da>dMRP4) by qt-PCR analysis. 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).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4256198&req=5

pgen-1004844-g006: dMRP4 regulates expression of some stress- and aging-related genes.(A) dMRP4 was required for basal expression of several stress- and aging-related genes. The mRNA levels of these genes were compared between w1118 and dMRP4 mutant (dMRP4M2/M2) by qt-PCR analysis. (B) Elevated expression of dMRP4 increased the basal expression of stress- and aging-related genes. The mRNA levels of these genes were compared between control Gal4 (da/+) and dMRP4 overexpression (da>dMRP4) by qt-PCR analysis. 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: In order to learn the molecular mechanism by which dMRP4 regulates lifespan, we selectively studied transcription profiling of several genes whose expression changes have been linked to both aging and stress [1]. Among five hsp (heat shock protein) genes examined, expression of three genes, hsp68, hsp70 and l(2)efl (lethal (2) essential for life, a small hsp gene) was severely down-regulated in dMRP4 mutant flies (Fig. 6A), while they were significantly up-regulated when dMRP4 was overexpressed (Fig. 6B). Overexpression of dMRP4 was also sufficient to increase expression of other two hsp genes, hsp22 and hsp83 (Fig. 6B). Since l(2)efl is a known target of dFOXO (Drosophila forkhead transcription factor) in lifespan regulation [52], it raised the possibility that dMRP4 might regulate expression of other dFOXO-dependent genes. Indeed, expression of the dFOXO target gene thor, which encodes 4E-BP (eIF4E binding protein), was also greatly enhanced when dMRP4 was overexpressed. Since both thor and hsp68 are target genes of JNK signaling [6], [52], we further examined expression patterns of several other JNK targets (Fig. 3A–D). Like hsp68, basal expression of puc and gstD1 was down-regulated in dMRP4 mutant flies and was up-regulated with dMRP4 overexpression (Fig. 6A–B). Furthermore, basal expression of Jafrac1 was increased when dMRP4 was overexpressed, even though its expression was not affected by dMRP4 mutation under normal condition. Thus, in addition to regulating the JNK-dependent gene expression under oxidative stress, dMRP4 also regulates the basal transcription of such genes under normal conditions.

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