Peroxisomal membrane proteins are properly targeted to peroxisomes in the absence of COPI- and COPII-mediated vesicular transport

2001 ◽  
Vol 114 (11) ◽  
pp. 2199-2204 ◽  
Author(s):  
Tineke Voorn-Brouwer ◽  
Astrid Kragt ◽  
Henk F. Tabak ◽  
Ben Distel
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Secretory Pathway ◽  
Human Fibroblasts ◽  
Vesicle Transport ◽  
Peroxisome Biogenesis ◽  
Peroxisomal Membrane ◽  
Classic Model ◽  
Early Secretory Pathway

The classic model for peroxisome biogenesis states that new peroxisomes arise by the fission of pre-existing ones and that peroxisomal matrix and membrane proteins are recruited directly from the cytosol. Recent studies challenge this model and suggest that some peroxisomal membrane proteins might traffic via the endoplasmic reticulum to peroxisomes. We have studied the trafficking in human fibroblasts of three peroxisomal membrane proteins, Pex2p, Pex3p and Pex16p, all of which have been suggested to transit the endoplasmic reticulum before arriving in peroxisomes. Here, we show that targeting of these peroxisomal membrane proteins is not affected by inhibitors of COPI and COPII that block vesicle transport in the early secretory pathway. Moreover, we have obtained no evidence for the presence of these peroxisomal membrane proteins in compartments other than peroxisomes and demonstrate that COPI and COPII inhibitors do not affect peroxisome morphology or integrity. Together, these data fail to provide any evidence for a role of the endoplasmic reticulum in peroxisome biogenesis.

The role of microtubules in transport between the endoplasmic reticulum and Golgi apparatus in mammalian cells.

2005 ◽  
Vol 72 ◽  
pp. 1-13 ◽  
Author(s):  
Krysten J. Palmer ◽  
Peter Watson ◽  
David J. Stephens
Keyword(s):  
Endoplasmic Reticulum ◽  
Mammalian Cells ◽  
Secretory Pathway ◽  
Motor Proteins ◽  
Microtubule Cytoskeleton ◽  
Early Secretory Pathway ◽  
Golgi Transport ◽  
Intracellular Compartments ◽  
Retrograde Traffic

The organization of intracellular compartments and the transfer of components between them are central to the correct functioning of mammalian cells. Proteins and lipids are transferred between compartments by the formation, movement and subsequent specific fusion of transport intermediates. These vesicles and membrane clusters must be coupled to the cytoskeleton and to motor proteins that drive motility. Anterograde ER (endoplasmic reticulum)-to-Golgi transport, and the converse step of retrograde traffic from the Golgi to the ER, are now known to involve coupling of membranes to the microtubule cytoskeleton. Here we shall discuss our current understanding of the mechanisms that link membrane traffic in the early secretory pathway to the microtubule cytoskeleton in mammalian cells. Recent data have also provided molecular detail of functional co-ordination of motor proteins to specify directionality, as well as mechanisms for regulating motor activity by protein phosphorylation.

scholarly journals Mutants of the Yeast Yarrowia lipolyticaDefective in Protein Exit from the Endoplasmic Reticulum Are Also Defective in Peroxisome Biogenesis

1998 ◽  
Vol 18 (5) ◽  
pp. 2789-2803 ◽  
Author(s):  
Vladimir I. Titorenko ◽  
Richard A. Rachubinski
Keyword(s):  
Endoplasmic Reticulum ◽  
Oleic Acid ◽  
Membrane Proteins ◽  
Matrix Proteins ◽  
Secretory Proteins ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Peroxisome Biogenesis ◽  
Peroxisomal Membrane ◽  
Mutant Cells

ABSTRACT Mutations in the SEC238 and SRP54 genes of the yeast Yarrowia lipolytica not only cause temperature-sensitive defects in the exit of the precursor form of alkaline extracellular protease and of other secretory proteins from the endoplasmic reticulum and in protein secretion but also lead to temperature-sensitive growth in oleic acid-containing medium, the metabolism of which requires the assembly of functionally intact peroxisomes. The sec238A andsrp54KO mutations at the restrictive temperature significantly reduce the size and number of peroxisomes, affect the import of peroxisomal matrix and membrane proteins into the organelle, and significantly delay, but do not prevent, the exit of two peroxisomal membrane proteins, Pex2p and Pex16p, from the endoplasmic reticulum en route to the peroxisomal membrane. Mutations in the PEX1 and PEX6 genes, which encode members of the AAA family of N-ethylmaleimide-sensitive fusion protein-like ATPases, not only affect the exit of precursor forms of secretory proteins from the endoplasmic reticulum but also prevent the exit of the peroxisomal membrane proteins Pex2p and Pex16p from the endoplasmic reticulum and cause the accumulation of an extensive network of endoplasmic reticulum membranes. None of the peroxisomal matrix proteins tested associated with the endoplasmic reticulum in sec238A,srp54KO, pex1-1, and pex6KO mutant cells. Our data provide evidence that the endoplasmic reticulum is required for peroxisome biogenesis and suggest that inY. lipolytica, the trafficking of some membrane proteins, but not matrix proteins, to the peroxisome occurs via the endoplasmic reticulum, results in their glycosylation within the lumen of the endoplasmic reticulum, does not involve transport through the Golgi, and requires the products encoded by the SEC238, SRP54,PEX1, and PEX6 genes.

scholarly journals Phosphorylation-dependent Pex11p and Fis1p interaction regulates peroxisome division

2012 ◽  
Vol 23 (7) ◽  
pp. 1307-1315 ◽  
Author(s):  
Saurabh Joshi ◽  
Gaurav Agrawal ◽  
Suresh Subramani
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Endoplasmic Reticulum ◽  
Pichia Pastoris ◽  
Peroxisome Biogenesis ◽  
Peroxisomal Membrane ◽  
Protein Levels ◽  
Protein Biogenesis ◽  
Peroxisome Division ◽  
Dependent Interaction

Peroxisome division is regulated by the conserved peroxin Pex11p. In Saccharomyces cerevisiae (Sc), induction of the phosphoprotein ScPex11p coincides with peroxisome biogenesis. We show that the ScPex11p homologue in Pichia pastoris (PpPex11p) is phosphorylated at serine 173. PpPex11p expression and phosphorylation are induced in oleate and coordinated with peroxisome biogenesis. PpPex11p transits to peroxisomes via the endoplasmic reticulum (ER). PpPex11p is unstable and ER restricted gin pex3Δ and pex19Δ cells, which are impaired in peroxisomal membrane protein biogenesis. In oleate medium, the P. pastoris mutants pex11A (constitutively unphosphorylated; S173A) and pex11D (constitutively phosphorylated; S173D) exhibit juxtaposed elongated peroxisomes (JEPs) and hyperdivided forms, respectively, although protein levels remain unchanged. In contrast with ScPex11p, the ER-to-peroxisome translocation in P. pastoris is phosphorylation independent, and the phosphorylation occurs at the peroxisome. We show that PpPex11p interacts with the peroxisome fission machinery via PpFis1p and is regulated by phosphorylation because PpPex11p and PpPex11Dp interact more strongly with PpFis1p than PpPex11Ap. Neither PpPex11p nor PpFis1p is necessary for peroxisome division in methanol medium. We propose a model for the role of PpPex11p in the regulation of peroxisome division through a phosphorylation-dependent interaction with the fission machinery, providing novel insights into peroxisome morphogenesis.

scholarly journals Endoplasmic Reticulum-Associated Secretory Proteins Sec20p, Sec39p, and Dsl1p Are Involved in Peroxisome Biogenesis

2009 ◽  
Vol 8 (6) ◽  
pp. 830-843 ◽  
Author(s):  
Ryan J. Perry ◽  
Fred D. Mast ◽  
Richard A. Rachubinski
Keyword(s):  
Endoplasmic Reticulum ◽  
Secretory Pathway ◽  
Matrix Protein ◽  
Fluorescent Protein ◽  
De Novo ◽  
Secretory Proteins ◽  
Peroxisome Biogenesis ◽  
Gfp Expression ◽  
Peroxisomal Membrane ◽  
Green Fluorescent

ABSTRACT Two pathways have been identified for peroxisome formation: (i) growth and division and (ii) de novo synthesis. Recent experiments determined that peroxisomes originate at the endoplasmic reticulum (ER). Although many proteins have been implicated in the peroxisome biogenic program, no proteins in the eukaryotic secretory pathway have been identified as having roles in peroxisome formation. Using the yeast Saccharomyces cerevisiae regulatable Tet promoter Hughes clone collection, we found that repression of the ER-associated secretory proteins Sec20p and Sec39p resulted in mislocalization of the peroxisomal matrix protein chimera Pot1p-green fluorescent protein (GFP) to the cytosol. Likewise, the peroxisomal membrane protein chimera Pex3p-GFP localized to tubular-vesicular structures in cells suppressed for Sec20p, Sec39p, and Dsl1p, which form a complex at the ER. Loss of Sec39p attenuated formation of Pex3p-derived peroxisomal structures following galactose induction of Pex3p-GFP expression from the GAL1 promoter. Expression of Sec20p, Sec39p, and Dsl1p was moderately increased in yeast grown under conditions that proliferate peroxisomes, and Sec20p, Sec39p, and Dsl1p were found to cofractionate with peroxisomes and colocalize with Pex3p-monomeric red fluorescent protein under these conditions. Our results show that SEC20, SEC39, and DSL1 are essential secretory genes involved in the early stages of peroxisome assembly, and this work is the first to identify and characterize an ER-associated secretory machinery involved in peroxisome biogenesis.

scholarly journals Distinct requirements for intra-ER sorting and budding of peroxisomal membrane proteins from the ER

2016 ◽  
Vol 212 (3) ◽  
pp. 335-348 ◽  
Author(s):  
Gaurav Agrawal ◽  
Scott N. Fassas ◽  
Zhi-Jie Xia ◽  
Suresh Subramani
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Ternary Complex ◽  
De Novo ◽  
Ring Domain ◽  
Peroxisome Biogenesis ◽  
Peroxisomal Membrane ◽  
Unique Role ◽  
Sorting Process

During de novo peroxisome biogenesis, importomer complex proteins sort via two preperoxisomal vesicles (ppVs). However, the sorting mechanisms segregating peroxisomal membrane proteins to the preperoxisomal endoplasmic reticulum (pER) and into ppVs are unknown. We report novel roles for Pex3 and Pex19 in intra–endoplasmic reticulum (ER) sorting and budding of the RING-domain peroxins (Pex2, Pex10, and Pex12). Pex19 bridged the interaction at the ER between Pex3 and RING-domain proteins, resulting in a ternary complex that was critical for the intra-ER sorting and subsequent budding of the RING-domain peroxins. Although the docking subcomplex proteins (Pex13, Pex14, and Pex17) also required Pex19 for budding from the ER, they sorted to the pER independently of Pex3 and Pex19 and were spatially segregated from the RING-domain proteins. We also discovered a unique role for Pex3 in sorting Pex10 and Pex12, but with the docking subcomplex. Our study describes an intra-ER sorting process that regulates segregation, packaging, and budding of peroxisomal importomer subcomplexes, thereby preventing their premature assembly at the ER.

scholarly journals Phospholipase C γ1 regulates early secretory trafficking and cell migration via interaction with p115

2015 ◽  
Vol 26 (12) ◽  
pp. 2263-2278 ◽  
Author(s):  
Valentina Millarte ◽  
Gaelle Boncompain ◽  
Kerstin Tillmann ◽  
Franck Perez ◽  
Elizabeth Sztul ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Migration ◽  
Phospholipase C ◽  
Small Interfering Rna ◽  
Secretory Pathway ◽  
Early Secretory Pathway ◽  
Catalytic Function ◽  
Golgi Structure ◽  
Interfering Rna

The role of early secretory trafficking in the regulation of cell motility remains incompletely understood. Here we used a small interfering RNA screen to monitor the effects on structure of the Golgi apparatus and cell migration. Two major Golgi phenotypes were observed—fragmented and small Golgi. The latter exhibited a stronger correlation with a defect in cell migration. Among the small Golgi hits, we focused on phospholipase C γ1 (PLCγ1). We show that PLCγ1 regulates Golgi structure and cell migration independently of its catalytic activity but in a manner that depends on interaction with the tethering protein p115. PLCγ1 regulates the dynamics of p115 in the early secretory pathway, thereby controlling trafficking from the endoplasmic reticulum to the Golgi. Our results uncover a new function of PLCγ1 that is independent of its catalytic function and link early secretory trafficking to the regulation of cell migration.

scholarly journals Life and Death of Fungal Transporters Under the Challenge of Polarity

2020 ◽  
Author(s):  
Sofia Dimou ◽  
George Diallinas
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Membrane Proteins ◽  
Cell Polarity ◽  
Secretory Pathway ◽  
Fungal Growth ◽  
Present Evidence ◽  
Life And Death ◽  
Early Endosomes ◽  
Stress Signals

Eukaryotic plasma membrane (PM) transporters face critical challenges that are not widely present in prokaryotes. The two most important issues are proper subcellular traffic and targeting to the PM, and regulated endocytosis in response to physiological, developmental or stress signals. Sorting of transporters from their site of synthesis, the Endoplasmic Reticulum (ER), to the PM has been long thought, but not formally shown, to occur via the conventional Golgi-dependent vesicular secretory pathway. Endocytosis of specific eukaryotic transporters has been studied more systematically and shown to involve ubiquitination, internalization, and sorting to early endosomes, followed by turnover in the MVB/lysosomes/vacuole system. In specific cases internalized transporters have been shown to recycle back to the PM. However, the mechanisms of transporter forward trafficking and turnover have been overturned recently through systematic work in the model fungus Aspergillus nidulans. In this review we present evidence that shows that transporter traffic to the PM takes place through Golgi-bypass and transporter endocytosis operates via a mechanism that is distinct from that of recycling membrane cargoes essential for fungal growth. We discuss these findings in relation to adaptation to challenges imposed by cell polarity in fungi as well as in other eukaryotes and provide a rationale why transporters and possibly other housekeeping membrane proteins ‘avoid’ routes of polar trafficking.

scholarly journals MIA3/TANGO1 enables efficient secretion by constraining COPII vesicle budding

2021 ◽  
Author(s):  
Janine McCaughey ◽  
Judith M. Mantell ◽  
Chris R. Neal ◽  
Kate Heesom ◽  
David J. Stephens
Keyword(s):  
Endoplasmic Reticulum ◽  
Light Microscopy ◽  
Secretory Pathway ◽  
Genome Engineering ◽  
High Volume ◽  
Vesicle Budding ◽  
Early Secretory Pathway ◽  
Copii Vesicle ◽  
Intermediate Compartment ◽  
Golgi Organization

AbstractComplex machinery is required to drive secretory cargo export from the endoplasmic reticulum. In vertebrates, this includes transport and Golgi organization protein 1 (TANGO1), encoded by the Mia3 gene. Here, using genome engineering of human cells light microscopy, secretion assays, and proteomics, we show loss of Mia3/TANGO1 results in formation of numerous vesicles and a loss of early secretory pathway integrity. This restricts secretion not only of large proteins like procollagens but of all types of secretory cargo. Our data shows that Mia3/TANGO1 constrains the propensity of COPII to form vesicles promoting instead the formation of the ER-Golgi intermediate compartment. Thus, Mia3/TANGO1 facilities the secretion of complex and high volume cargoes from vertebrate cells.

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