Limits...
AMP-Activated Kinase Regulates Lipid Droplet Localization and Stability of Adipose Triglyceride Lipase in C. elegans Dauer Larvae.

Xie M, Roy R - PLoS ONE (2015)

Bottom Line: Physical interaction of ATGL-1 with PAR-5 results in sequestration of ATGL-1 away from the lipid droplets and eventual proteasome-mediated degradation.In addition, we also show that the major AMPK phosphorylation site on ATGL-1, Ser 303, is required for both modification of its lipid droplet localization and its degradation.Our data provide mechanistic insight as to how AMPK functions to enhance survival through its ability to protect the accumulated triglyceride deposits from rapid hydrolysis to preserve the energy stores during periods of extended environmental duress.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, McGill University, 1205 avenue Docteur Penfield, Montreal, Canada.

ABSTRACT
Animals have developed diverse mechanisms to adapt to their changing environment. Like many organisms the free-living nematode C. elegans can alternate between a reproductive mode or a diapause-like "dauer" stage during larval development to circumvent harsh environmental conditions. The master metabolic regulator AMP-activated protein kinase (AMPK) is critical for survival during the dauer stage, where it phosphorylates adipose triglyceride lipase (ATGL-1) at multiple sites to block lipid hydrolysis and ultimately protect the cellular triglyceride-based energy depot from rapid depletion. However, how the AMPK-mediated phosphorylation affects the function of ATGL-1 has not been characterised at the molecular level. Here we show that AMPK phosphorylation leads to the generation of 14-3-3 binding sites on ATGL-1, which are recognized by the C. elegans 14-3-3 protein orthologue PAR-5. Physical interaction of ATGL-1 with PAR-5 results in sequestration of ATGL-1 away from the lipid droplets and eventual proteasome-mediated degradation. In addition, we also show that the major AMPK phosphorylation site on ATGL-1, Ser 303, is required for both modification of its lipid droplet localization and its degradation. Our data provide mechanistic insight as to how AMPK functions to enhance survival through its ability to protect the accumulated triglyceride deposits from rapid hydrolysis to preserve the energy stores during periods of extended environmental duress.

No MeSH data available.


Endogenous ATGL-1 Protein is More Abundant in AMPK-deficient Dauer Larvae.(A) The ATGL-1 antisera recognizes a single band that migrates at approximately 70kD, which corresponds to the molecular weight of ATGL-1, and is eliminated in atgl-1(RNAi) animals. (B) Western blot analysis with C. elegans specific ATGL-1 antibody in daf-2; aak(0) mutant dauer larvae and control daf-2 dauer larvae during the period of dauer entry. (C) mRNA Expression levels of ATGL-1 in control daf-2 and daf-2; aak(0) dauers. Relative mRNA levels were analyzed by quantitative real-time PCR in dauer day 0 animals.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4476745&req=5

pone.0130480.g003: Endogenous ATGL-1 Protein is More Abundant in AMPK-deficient Dauer Larvae.(A) The ATGL-1 antisera recognizes a single band that migrates at approximately 70kD, which corresponds to the molecular weight of ATGL-1, and is eliminated in atgl-1(RNAi) animals. (B) Western blot analysis with C. elegans specific ATGL-1 antibody in daf-2; aak(0) mutant dauer larvae and control daf-2 dauer larvae during the period of dauer entry. (C) mRNA Expression levels of ATGL-1 in control daf-2 and daf-2; aak(0) dauers. Relative mRNA levels were analyzed by quantitative real-time PCR in dauer day 0 animals.

Mentions: Using a polyclonal antibody raised specifically against C. elegans ATGL-1 (Fig 3A) we performed a Western blot analysis on day 0 control daf-2 and daf-2; aak(0) dauer larvae. We noted that the endogenous ATGL-1 protein was significantly more abundant in the absence of AMPK at all the time points tested during the entire dauer entry period, consistent with the GFP expression analysis (Fig 3B). It is worth mentioning that the atgl-1 mRNA levels were identical in both genetic backgrounds indicating that these differences resulted exclusively from post-transcriptional effects (Fig 3C).


AMP-Activated Kinase Regulates Lipid Droplet Localization and Stability of Adipose Triglyceride Lipase in C. elegans Dauer Larvae.

Xie M, Roy R - PLoS ONE (2015)

Endogenous ATGL-1 Protein is More Abundant in AMPK-deficient Dauer Larvae.(A) The ATGL-1 antisera recognizes a single band that migrates at approximately 70kD, which corresponds to the molecular weight of ATGL-1, and is eliminated in atgl-1(RNAi) animals. (B) Western blot analysis with C. elegans specific ATGL-1 antibody in daf-2; aak(0) mutant dauer larvae and control daf-2 dauer larvae during the period of dauer entry. (C) mRNA Expression levels of ATGL-1 in control daf-2 and daf-2; aak(0) dauers. Relative mRNA levels were analyzed by quantitative real-time PCR in dauer day 0 animals.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4476745&req=5

pone.0130480.g003: Endogenous ATGL-1 Protein is More Abundant in AMPK-deficient Dauer Larvae.(A) The ATGL-1 antisera recognizes a single band that migrates at approximately 70kD, which corresponds to the molecular weight of ATGL-1, and is eliminated in atgl-1(RNAi) animals. (B) Western blot analysis with C. elegans specific ATGL-1 antibody in daf-2; aak(0) mutant dauer larvae and control daf-2 dauer larvae during the period of dauer entry. (C) mRNA Expression levels of ATGL-1 in control daf-2 and daf-2; aak(0) dauers. Relative mRNA levels were analyzed by quantitative real-time PCR in dauer day 0 animals.
Mentions: Using a polyclonal antibody raised specifically against C. elegans ATGL-1 (Fig 3A) we performed a Western blot analysis on day 0 control daf-2 and daf-2; aak(0) dauer larvae. We noted that the endogenous ATGL-1 protein was significantly more abundant in the absence of AMPK at all the time points tested during the entire dauer entry period, consistent with the GFP expression analysis (Fig 3B). It is worth mentioning that the atgl-1 mRNA levels were identical in both genetic backgrounds indicating that these differences resulted exclusively from post-transcriptional effects (Fig 3C).

Bottom Line: Physical interaction of ATGL-1 with PAR-5 results in sequestration of ATGL-1 away from the lipid droplets and eventual proteasome-mediated degradation.In addition, we also show that the major AMPK phosphorylation site on ATGL-1, Ser 303, is required for both modification of its lipid droplet localization and its degradation.Our data provide mechanistic insight as to how AMPK functions to enhance survival through its ability to protect the accumulated triglyceride deposits from rapid hydrolysis to preserve the energy stores during periods of extended environmental duress.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, McGill University, 1205 avenue Docteur Penfield, Montreal, Canada.

ABSTRACT
Animals have developed diverse mechanisms to adapt to their changing environment. Like many organisms the free-living nematode C. elegans can alternate between a reproductive mode or a diapause-like "dauer" stage during larval development to circumvent harsh environmental conditions. The master metabolic regulator AMP-activated protein kinase (AMPK) is critical for survival during the dauer stage, where it phosphorylates adipose triglyceride lipase (ATGL-1) at multiple sites to block lipid hydrolysis and ultimately protect the cellular triglyceride-based energy depot from rapid depletion. However, how the AMPK-mediated phosphorylation affects the function of ATGL-1 has not been characterised at the molecular level. Here we show that AMPK phosphorylation leads to the generation of 14-3-3 binding sites on ATGL-1, which are recognized by the C. elegans 14-3-3 protein orthologue PAR-5. Physical interaction of ATGL-1 with PAR-5 results in sequestration of ATGL-1 away from the lipid droplets and eventual proteasome-mediated degradation. In addition, we also show that the major AMPK phosphorylation site on ATGL-1, Ser 303, is required for both modification of its lipid droplet localization and its degradation. Our data provide mechanistic insight as to how AMPK functions to enhance survival through its ability to protect the accumulated triglyceride deposits from rapid hydrolysis to preserve the energy stores during periods of extended environmental duress.

No MeSH data available.