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Repression of mitochondrial translation, respiration and a metabolic cycle-regulated gene, SLF1, by the yeast Pumilio-family protein Puf3p.

Chatenay-Lapointe M, Shadel GS - PLoS ONE (2011)

Bottom Line: Multiple functions have been assigned to Puf3p, including promoting mRNA degradation, localizing nucleus-encoded mitochondrial transcripts to the outer mitochondrial membrane, and facilitating mitochondria-cytoskeletal interactions and motility.Here we show that Puf3p has a general repressive effect on mitochondrial OXPHOS abundance, translation, and respiration that does not involve changes in overall mitochondrial biogenesis and largely independent of TORC1-mitochondrial signaling.Altogether, these results should facilitate future studies on which of the many functions of Puf3p is most relevant for regulating mitochondrial gene expression and the role of nuclear-mitochondrial communication in aging and longevity.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Yale University School of Medicine, New Haven, Connecticut, United States of America.

ABSTRACT
Synthesis and assembly of the mitochondrial oxidative phosphorylation (OXPHOS) system requires genes located both in the nuclear and mitochondrial genomes, but how gene expression is coordinated between these two compartments is not fully understood. One level of control is through regulated expression mitochondrial ribosomal proteins and other factors required for mitochondrial translation and OXPHOS assembly, which are all products of nuclear genes that are subsequently imported into mitochondria. Interestingly, this cadre of genes in budding yeast has in common a 3'-UTR element that is bound by the Pumilio family protein, Puf3p, and is coordinately regulated under many conditions, including during the yeast metabolic cycle. Multiple functions have been assigned to Puf3p, including promoting mRNA degradation, localizing nucleus-encoded mitochondrial transcripts to the outer mitochondrial membrane, and facilitating mitochondria-cytoskeletal interactions and motility. Here we show that Puf3p has a general repressive effect on mitochondrial OXPHOS abundance, translation, and respiration that does not involve changes in overall mitochondrial biogenesis and largely independent of TORC1-mitochondrial signaling. We also identified the cytoplasmic translation factor Slf1p as yeast metabolic cycle-regulated gene that is repressed by Puf3p at the post-transcriptional level and promotes respiration and extension of yeast chronological life span when over-expressed. Altogether, these results should facilitate future studies on which of the many functions of Puf3p is most relevant for regulating mitochondrial gene expression and the role of nuclear-mitochondrial communication in aging and longevity.

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Chronological Aging in strains that lack or over-express Puf3p.Shown are chronological life span curves (viability as a function of time in days of stationary phase) of wild-type strain compared to isogenic puf3Δ, tor1Δ, and puf3Δ tor1Δ strains (A), a wild-type strain with an empty vector or a plasmid that over-expresses PUF3 (B), or a tor1Δ strain with an empty vector or a plasmid that over-expresses PUF3 (C). Each point is the mean +/− SD of three biological replicates.
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pone-0020441-g004: Chronological Aging in strains that lack or over-express Puf3p.Shown are chronological life span curves (viability as a function of time in days of stationary phase) of wild-type strain compared to isogenic puf3Δ, tor1Δ, and puf3Δ tor1Δ strains (A), a wild-type strain with an empty vector or a plasmid that over-expresses PUF3 (B), or a tor1Δ strain with an empty vector or a plasmid that over-expresses PUF3 (C). Each point is the mean +/− SD of three biological replicates.

Mentions: Reactive oxygen species (ROS) are produced during metabolism and are thought to contribute to aging. For example, they are generated by the mitochondrial electron transport chain, placing these organelles at the nexus of oxidative stress and aging according to the mitochondrial theory of aging. We found previously [26], [27] that reduced TORC1 signaling increases the density of OXPHOS complexes in a manner that reduces ROS in stationary phase and extends yeast chronological life span. Given that similar changes in OXPHOS abundance and respiration are observed in a puf3Δ strain (Figure 1), we ascertained whether Puf3p is involved in regulating CLS and/or is a downstream effector of TORC1 effects on mitochondrial function. However, deletion of PUF3 in wild-type or tor1Δ strains did not affect CLS (Figure 4A). Furthermore, no difference in CLS were observed in a wild-type strain that over-expresses Puf3p (Figure 4B). However, over-expression of Puf3p did partially reduce the extended CLS of a tor1Δ strain (Figure 4C).


Repression of mitochondrial translation, respiration and a metabolic cycle-regulated gene, SLF1, by the yeast Pumilio-family protein Puf3p.

Chatenay-Lapointe M, Shadel GS - PLoS ONE (2011)

Chronological Aging in strains that lack or over-express Puf3p.Shown are chronological life span curves (viability as a function of time in days of stationary phase) of wild-type strain compared to isogenic puf3Δ, tor1Δ, and puf3Δ tor1Δ strains (A), a wild-type strain with an empty vector or a plasmid that over-expresses PUF3 (B), or a tor1Δ strain with an empty vector or a plasmid that over-expresses PUF3 (C). Each point is the mean +/− SD of three biological replicates.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3105058&req=5

pone-0020441-g004: Chronological Aging in strains that lack or over-express Puf3p.Shown are chronological life span curves (viability as a function of time in days of stationary phase) of wild-type strain compared to isogenic puf3Δ, tor1Δ, and puf3Δ tor1Δ strains (A), a wild-type strain with an empty vector or a plasmid that over-expresses PUF3 (B), or a tor1Δ strain with an empty vector or a plasmid that over-expresses PUF3 (C). Each point is the mean +/− SD of three biological replicates.
Mentions: Reactive oxygen species (ROS) are produced during metabolism and are thought to contribute to aging. For example, they are generated by the mitochondrial electron transport chain, placing these organelles at the nexus of oxidative stress and aging according to the mitochondrial theory of aging. We found previously [26], [27] that reduced TORC1 signaling increases the density of OXPHOS complexes in a manner that reduces ROS in stationary phase and extends yeast chronological life span. Given that similar changes in OXPHOS abundance and respiration are observed in a puf3Δ strain (Figure 1), we ascertained whether Puf3p is involved in regulating CLS and/or is a downstream effector of TORC1 effects on mitochondrial function. However, deletion of PUF3 in wild-type or tor1Δ strains did not affect CLS (Figure 4A). Furthermore, no difference in CLS were observed in a wild-type strain that over-expresses Puf3p (Figure 4B). However, over-expression of Puf3p did partially reduce the extended CLS of a tor1Δ strain (Figure 4C).

Bottom Line: Multiple functions have been assigned to Puf3p, including promoting mRNA degradation, localizing nucleus-encoded mitochondrial transcripts to the outer mitochondrial membrane, and facilitating mitochondria-cytoskeletal interactions and motility.Here we show that Puf3p has a general repressive effect on mitochondrial OXPHOS abundance, translation, and respiration that does not involve changes in overall mitochondrial biogenesis and largely independent of TORC1-mitochondrial signaling.Altogether, these results should facilitate future studies on which of the many functions of Puf3p is most relevant for regulating mitochondrial gene expression and the role of nuclear-mitochondrial communication in aging and longevity.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Yale University School of Medicine, New Haven, Connecticut, United States of America.

ABSTRACT
Synthesis and assembly of the mitochondrial oxidative phosphorylation (OXPHOS) system requires genes located both in the nuclear and mitochondrial genomes, but how gene expression is coordinated between these two compartments is not fully understood. One level of control is through regulated expression mitochondrial ribosomal proteins and other factors required for mitochondrial translation and OXPHOS assembly, which are all products of nuclear genes that are subsequently imported into mitochondria. Interestingly, this cadre of genes in budding yeast has in common a 3'-UTR element that is bound by the Pumilio family protein, Puf3p, and is coordinately regulated under many conditions, including during the yeast metabolic cycle. Multiple functions have been assigned to Puf3p, including promoting mRNA degradation, localizing nucleus-encoded mitochondrial transcripts to the outer mitochondrial membrane, and facilitating mitochondria-cytoskeletal interactions and motility. Here we show that Puf3p has a general repressive effect on mitochondrial OXPHOS abundance, translation, and respiration that does not involve changes in overall mitochondrial biogenesis and largely independent of TORC1-mitochondrial signaling. We also identified the cytoplasmic translation factor Slf1p as yeast metabolic cycle-regulated gene that is repressed by Puf3p at the post-transcriptional level and promotes respiration and extension of yeast chronological life span when over-expressed. Altogether, these results should facilitate future studies on which of the many functions of Puf3p is most relevant for regulating mitochondrial gene expression and the role of nuclear-mitochondrial communication in aging and longevity.

Show MeSH
Related in: MedlinePlus