Macropexophagy in <i>Hansenula polymorpha</i>: facts and views

Kiel, Jan A.K.W.; Komduur, Janet A; Klei, Ida J. van der; Veenhuis, Marten

doi:10.1016/s0014-5793(03)00794-4

Cited by 50 publications

(55 citation statements)

References 40 publications

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“…In the methylotrophic yeasts Pichia pastoris and Hansenula polymorpha selective degradation of giant peroxisomes has been described as the direct engulfment of peroxisomes by the vacuole. 2,3 In these organisms, two morphologically distinct processes, termed micropexophagy and macropexophagy, are induced by different stimuli, but they seem to be regulated, at least partially, by the same proteins. [4][5][6] Selective degradation of peroxisomes has also been evidenced in Saccharomyces cerevisiae and in mammals.…”

Section: Introductionmentioning

confidence: 99%

Selective and Non-Selective Autophagic Degradation of Mitochondria in Yeast

et al. 2007

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Mitochondria are essential to oxidative energy production in aerobic eukaryotic cells, where they are also required for multiple biosynthetic pathways to take place. Mitochondrial homeostasis also plays a crucial role in ageing and programmed cell death, and recent data have suggested that mitochondria degradation is a strictly regulated process. Autophagy is an evolutionary conserved mechanism that provides cells with a mechanism for the continuous turnover of damaged and obsolete macromolecules and organelles. In this work, we investigated mitochondria degradation by autophagy. Electron microscopy observations of yeast cells submitted to nitrogen starvation after growth on different carbon sources provided evidence that microautophagy, rather than macroautophagy, preferentially occurred in cells grown under nonfermentable conditions. The observation of mitochondria degradation showed that both a selective process and a nonselective process of mitochondria autophagy occurred successively. In a yeast strain inactivated for the gene UTH1, the selective process was not observed.

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Section: Introductionmentioning

confidence: 99%

Selective and Non-Selective Autophagic Degradation of Mitochondria in Yeast

et al. 2007

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“…1,2 For example, peroxisomes that participate in hydrogen peroxide and fatty acid metabolism are proliferated in lower eukaryotes such as Saccharomyces cerevisiae, Hansenula polymorpha and Pichia pastoris and in mammalian cells during growth on fatty acids. [3][4][5] Alterations in nutrient conditions induce rapid and extensive peroxisome degradation whereas other organelles such as mitochondria, Golgi and cytosolic proteins show much lower levels of degradation, suggesting that the elimination of peroxisomes is selective. 3 The ER is selectively sequestered in autophagosomal structures induced when the unfolded protein response is overwhelmed.…”

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Delivery of cytoplasmic proteins to autophagosomes

Ohshiro

Rayala

El‐Naggar³

et al. 2008

Autophagy

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“…Autophagy is the subject of a recent book [10], and excellent reviews have been written about the biological roles of autophagy and the involvement of ATG genes in autophagy and Cvt pathways [4,11,12,[19][20][21][22]. The degradation of peroxisomes in Hansenula polymorpha by macropexophagy has also been reviewed recently [16,23,24]. This article highlights the mechanism of micropexophagy [17], for which the morphological intermediates and the proteins involved have been discovered only recently.…”

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confidence: 99%

“…Peroxisomes are dynamic organelles that can be induced [1,66] or turned over in response to extracellular cues in yeasts and mammals [1,66,67]. Peroxisome number can thus be regulated by modulation of biogenesis [66] or degradation [19,23,68,69]. The steady-state level (homeostasis) of peroxisomes in any cell is tightly controlled by the net balance between the biogenesis and turnover of the organelle.…”

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Peroxisome turnover by micropexophagy: an autophagy-related process

Farré

Subramani

2004

Trends in Cell Biology

153

133

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Many organisms stringently regulate the number, volume and enzymatic content of peroxisomes (and other organelles). Understanding this regulation requires knowledge of how organelles are assembled and selectively destroyed in response to metabolic cues. In the past decade, considerable progress has been achieved in the elucidation of the roles of genes involved in peroxisome biogenesis, half of which are affected in human peroxisomal disorders. The recent discovery of intermediates and genes in peroxisome turnover by selective autophagy-related processes (pexophagy) opens the door to understanding peroxisome turnover and homeostasis. In this article, we summarize advances in the characterization of genes that are necessary for the transport and delivery of selective and nonselective cargos to the lysosome or vacuole by autophagy-related processes, with emphasis on peroxisome turnover by micropexophagy.During autophagy, cargos consisting of individual proteins, bulk cytosol and/or subcellular organelles, are degraded in the lysosome (or vacuole in yeast), with ensuing recycling of the amino acid and lipid precursors. Although autophagy was thought initially to enable cells to survive nutrient starvation by degradation and recycling of dispensable cellular components, it is now recognized to be involved in a plethora of cellular responses, including the regulation of organelle number [1][2][3] Autophagy is universal to all eukaryotic cells, including yeasts, worms, insects, plants and mammals [10]. In unicellular organisms, such as yeasts, it is observed primarily under nutrient starvation conditions or during the re-adaptation of cells switched from certain environments to others. Two morphologically distinct, but mechanistically related, forms of autophagy common to uni-and multicellular eukaryotes have been described. These are macroautophagy and microautophagy (Figure 1). A third form, called chaperone-mediated autophagy, has been found only in mammalian systems and is described elsewhere [9]. Autophagy is often a degradative process but it can be either selective or nonselective with respect to cargo that is turned over. The degradation of nonselective cargo is a mechanism for recycling any excess cellular components (e.g. cytosol and/or organelles) and might be a strategy for adaptation to different environments. By contrast, cells resort to selective autophagic turnover of nonfunctional or damaged organelles, or protein aggregates, that might be too large for other proteolysis machinery, such as the proteasome.Unlike the autophagic pathways, the related cytosol-tovacuole transport (Cvt) pathway, described to date only in Saccharomyces cerevisiae, delivers a limited set of specific, Morphological steps in the cytosol-to-vacuole transport (Cvt), macroautophagy and microautophagy pathways in yeast. In microautophagy, organelles and/or cytosolic proteins are engulfed by the vacuolar membrane in a Pac-Manelike fashion and degraded in the vacuolar lumen. Macroautophagy involves the formation of large (300-900 nm)...

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Macropexophagy in Hansenula polymorpha: facts and views

Cited by 50 publications

References 40 publications

Selective and Non-Selective Autophagic Degradation of Mitochondria in Yeast

Selective and Non-Selective Autophagic Degradation of Mitochondria in Yeast

Delivery of cytoplasmic proteins to autophagosomes

Peroxisome turnover by micropexophagy: an autophagy-related process

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