Limits...
Mitochondrial dysfunction confers resistance to multiple drugs in Caenorhabditis elegans.

Zubovych IO, Straud S, Roth MG - Mol. Biol. Cell (2010)

Bottom Line: Two of these were found to be resistant to multiple toxins, and in one of these we identified a missense mutation in phb-2, which encodes the mitochondrial protein prohibitin 2.Other mitochondrial mutants, isp-1, eat-3, and clk-1, were also found to be drug-resistant.Using genetics, we show that this drug resistance requires pkc-1, the C. elegans ortholog of human PKCepsilon.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, The University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9038, USA.

ABSTRACT
In a previous genetic screen for Caenorhabditis elegans mutants that survive in the presence of an antimitotic drug, hemiasterlin, we identified eight strong mutants. Two of these were found to be resistant to multiple toxins, and in one of these we identified a missense mutation in phb-2, which encodes the mitochondrial protein prohibitin 2. Here we identify two additional mutations that confer drug resistance, spg-7 and har-1, also in genes encoding mitochondrial proteins. Other mitochondrial mutants, isp-1, eat-3, and clk-1, were also found to be drug-resistant. Respiratory complex inhibitors, FCCP and oligomycin, and a producer of reactive oxygen species (ROS), paraquat, all rescued wild-type worms from hemiasterlin toxicity. Worms lacking mitochondrial superoxide dismutase (MnSOD) were modestly drug-resistant, and elimination of MnSOD in the phb-2, har-1, and spg-7 mutants enhanced resistance. The antioxidant N-acetyl-l-cysteine prevented mitochondrial inhibitors from rescuing wild-type worms from hemiasterlin and sensitized mutants to the toxin, suggesting that a mechanism sensitive to ROS is necessary to trigger drug resistance in C. elegans. Using genetics, we show that this drug resistance requires pkc-1, the C. elegans ortholog of human PKCepsilon.

Show MeSH

Related in: MedlinePlus

AMPK is activated in phb-2, har-1, and spg-7, suggesting impaired ATP production. Wild-type and mutant adult worms were lysed and analyzed by immunoblotting with an antibody that recognizes phosphorylated T172 on AMPK-α. The blot was reprobed with antibody to actin.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2836976&req=5

Figure 4: AMPK is activated in phb-2, har-1, and spg-7, suggesting impaired ATP production. Wild-type and mutant adult worms were lysed and analyzed by immunoblotting with an antibody that recognizes phosphorylated T172 on AMPK-α. The blot was reprobed with antibody to actin.

Mentions: AMPK is activated by an elevated AMP/ATP ratio, and phosphorylation on Thr172 is an important response to cellular metabolic stress (Hardie, 2004). To determine if the mutations in phb-2, har-1, and spg-7 activated AMPK, lysates from each of the worm strains were probed by immunoblotting with an antibody to phosphorylated Thr172 (Figure 4). We observed higher activity of AMPK in the mutant animals compared with wild-type worms, suggesting that the mutants likely produce less ATP than wild-type worms. Lower ATP production suggests that the mitochondria in the mutant worms might work less efficiently.


Mitochondrial dysfunction confers resistance to multiple drugs in Caenorhabditis elegans.

Zubovych IO, Straud S, Roth MG - Mol. Biol. Cell (2010)

AMPK is activated in phb-2, har-1, and spg-7, suggesting impaired ATP production. Wild-type and mutant adult worms were lysed and analyzed by immunoblotting with an antibody that recognizes phosphorylated T172 on AMPK-α. The blot was reprobed with antibody to actin.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2836976&req=5

Figure 4: AMPK is activated in phb-2, har-1, and spg-7, suggesting impaired ATP production. Wild-type and mutant adult worms were lysed and analyzed by immunoblotting with an antibody that recognizes phosphorylated T172 on AMPK-α. The blot was reprobed with antibody to actin.
Mentions: AMPK is activated by an elevated AMP/ATP ratio, and phosphorylation on Thr172 is an important response to cellular metabolic stress (Hardie, 2004). To determine if the mutations in phb-2, har-1, and spg-7 activated AMPK, lysates from each of the worm strains were probed by immunoblotting with an antibody to phosphorylated Thr172 (Figure 4). We observed higher activity of AMPK in the mutant animals compared with wild-type worms, suggesting that the mutants likely produce less ATP than wild-type worms. Lower ATP production suggests that the mitochondria in the mutant worms might work less efficiently.

Bottom Line: Two of these were found to be resistant to multiple toxins, and in one of these we identified a missense mutation in phb-2, which encodes the mitochondrial protein prohibitin 2.Other mitochondrial mutants, isp-1, eat-3, and clk-1, were also found to be drug-resistant.Using genetics, we show that this drug resistance requires pkc-1, the C. elegans ortholog of human PKCepsilon.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, The University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9038, USA.

ABSTRACT
In a previous genetic screen for Caenorhabditis elegans mutants that survive in the presence of an antimitotic drug, hemiasterlin, we identified eight strong mutants. Two of these were found to be resistant to multiple toxins, and in one of these we identified a missense mutation in phb-2, which encodes the mitochondrial protein prohibitin 2. Here we identify two additional mutations that confer drug resistance, spg-7 and har-1, also in genes encoding mitochondrial proteins. Other mitochondrial mutants, isp-1, eat-3, and clk-1, were also found to be drug-resistant. Respiratory complex inhibitors, FCCP and oligomycin, and a producer of reactive oxygen species (ROS), paraquat, all rescued wild-type worms from hemiasterlin toxicity. Worms lacking mitochondrial superoxide dismutase (MnSOD) were modestly drug-resistant, and elimination of MnSOD in the phb-2, har-1, and spg-7 mutants enhanced resistance. The antioxidant N-acetyl-l-cysteine prevented mitochondrial inhibitors from rescuing wild-type worms from hemiasterlin and sensitized mutants to the toxin, suggesting that a mechanism sensitive to ROS is necessary to trigger drug resistance in C. elegans. Using genetics, we show that this drug resistance requires pkc-1, the C. elegans ortholog of human PKCepsilon.

Show MeSH
Related in: MedlinePlus