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Yeast Miro GTPase, Gem1p, regulates mitochondrial morphology via a novel pathway.

Frederick RL, McCaffery JM, Cunningham KW, Okamoto K, Shaw JM - J. Cell Biol. (2004)

Bottom Line: Biol.Chem. 278:6495-6502), Gem1p is not required for pheromone-induced yeast cell death.Thus, Gem1p defines a novel mitochondrial morphology pathway which may integrate cell signaling events with mitochondrial dynamics.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Utah, Salt Lake City, UT 84112, USA.

ABSTRACT
Cell signaling events elicit changes in mitochondrial shape and activity. However, few mitochondrial proteins that interact with signaling pathways have been identified. Candidates include the conserved mitochondrial Rho (Miro) family of proteins, which contain two GTPase domains flanking a pair of calcium-binding EF-hand motifs. We show that Gem1p (yeast Miro; encoded by YAL048C) is a tail-anchored outer mitochondrial membrane protein. Cells lacking Gem1p contain collapsed, globular, or grape-like mitochondria. We demonstrate that Gem1p is not an essential component of characterized pathways that regulate mitochondrial dynamics. Genetic studies indicate both GTPase domains and EF-hand motifs, which are exposed to the cytoplasm, are required for Gem1p function. Although overexpression of a mutant human Miro protein caused increased apoptotic activity in cultured cells (Fransson et al., 2003. J. Biol. Chem. 278:6495-6502), Gem1p is not required for pheromone-induced yeast cell death. Thus, Gem1p defines a novel mitochondrial morphology pathway which may integrate cell signaling events with mitochondrial dynamics.

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GFP-Gem1p localizes to mitochondria. Wild-type cells (JSY7000) with pYX142-GFP-GEM1 were grown to late log phase (OD600 ∼2) in SDextrose. Mitochondria were stained with MitoFluor red 589. Bar, 5 μm.
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fig6: GFP-Gem1p localizes to mitochondria. Wild-type cells (JSY7000) with pYX142-GFP-GEM1 were grown to late log phase (OD600 ∼2) in SDextrose. Mitochondria were stained with MitoFluor red 589. Bar, 5 μm.

Mentions: To determine where Gem1p localizes in vivo, we fused GFP to the NH2 terminus of a constitutively expressed Gem1p (pYX142-GFP-GEM1). This construct complements the glycerol growth (Fig. 2 B) and mitochondrial morphology defects (Table I) of gem1 cells at 30°C. When expressed in wild-type cells, GFP-Gem1p uniformly labeled mitochondrial tubules that were costained with MitoFluor red 589 (Fig. 6).


Yeast Miro GTPase, Gem1p, regulates mitochondrial morphology via a novel pathway.

Frederick RL, McCaffery JM, Cunningham KW, Okamoto K, Shaw JM - J. Cell Biol. (2004)

GFP-Gem1p localizes to mitochondria. Wild-type cells (JSY7000) with pYX142-GFP-GEM1 were grown to late log phase (OD600 ∼2) in SDextrose. Mitochondria were stained with MitoFluor red 589. Bar, 5 μm.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2172521&req=5

fig6: GFP-Gem1p localizes to mitochondria. Wild-type cells (JSY7000) with pYX142-GFP-GEM1 were grown to late log phase (OD600 ∼2) in SDextrose. Mitochondria were stained with MitoFluor red 589. Bar, 5 μm.
Mentions: To determine where Gem1p localizes in vivo, we fused GFP to the NH2 terminus of a constitutively expressed Gem1p (pYX142-GFP-GEM1). This construct complements the glycerol growth (Fig. 2 B) and mitochondrial morphology defects (Table I) of gem1 cells at 30°C. When expressed in wild-type cells, GFP-Gem1p uniformly labeled mitochondrial tubules that were costained with MitoFluor red 589 (Fig. 6).

Bottom Line: Biol.Chem. 278:6495-6502), Gem1p is not required for pheromone-induced yeast cell death.Thus, Gem1p defines a novel mitochondrial morphology pathway which may integrate cell signaling events with mitochondrial dynamics.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Utah, Salt Lake City, UT 84112, USA.

ABSTRACT
Cell signaling events elicit changes in mitochondrial shape and activity. However, few mitochondrial proteins that interact with signaling pathways have been identified. Candidates include the conserved mitochondrial Rho (Miro) family of proteins, which contain two GTPase domains flanking a pair of calcium-binding EF-hand motifs. We show that Gem1p (yeast Miro; encoded by YAL048C) is a tail-anchored outer mitochondrial membrane protein. Cells lacking Gem1p contain collapsed, globular, or grape-like mitochondria. We demonstrate that Gem1p is not an essential component of characterized pathways that regulate mitochondrial dynamics. Genetic studies indicate both GTPase domains and EF-hand motifs, which are exposed to the cytoplasm, are required for Gem1p function. Although overexpression of a mutant human Miro protein caused increased apoptotic activity in cultured cells (Fransson et al., 2003. J. Biol. Chem. 278:6495-6502), Gem1p is not required for pheromone-induced yeast cell death. Thus, Gem1p defines a novel mitochondrial morphology pathway which may integrate cell signaling events with mitochondrial dynamics.

Show MeSH