Clathrin light chains function in mannose phosphate receptor trafficking via regulation of actin assembly

Poupon, Viviane; Girard, Martine; Legendre-Guillemin, Valerie; Thomas, Sébastien; Bourbonnière, Lyne; Philie, Jacynthe; Bright, Nicholas A.; McPherson, Peter S.

doi:10.1073/pnas.0707269105

Cited by 79 publications

(120 citation statements)

References 55 publications

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“…Thus, CLCs are dispensable for uptake of some GPCRs, as further observed in transfected cells, displaying CLCdependent internalization of DOR, but not β2AR. Our findings plus earlier observations that CLCs are required for internalization of some GPCRs (5), but not several classical CCV cargoes (3,4), suggest that CLCs are needed for endocytosis depending on the type and/or configuration of cargo present in a clathrin-coated pit. Variations in cargo crowding and local lipid organization affect membrane-bending properties, which in turn require different coat properties for deformation into a vesicle (35).…”

Section: Clc Depletion From Cell Lines Establishes Selectivity For DIsupporting

confidence: 65%

“…Vertebrates have two CLC isoforms, CLCa and CLCb, encoded by separate genes, CLTA and CLTB (1). Depletion of both isoforms from tissue culture cells by siRNA treatment showed that CLCs are not required for clathrin-mediated uptake of classic CCV cargoes, such as transferrin receptor (TfR), epidermal growth factor receptor, or low-density lipoprotein receptor (2)(3)(4). CLCs were, however, implicated in uptake of three G protein-coupled receptors (GPCRs) (5).…”

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confidence: 99%

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Clathrin light chains’ role in selective endocytosis influences antibody isotype switching

Majeed

Evans

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Clathrin, a cytosolic protein composed of heavy and light chain subunits, assembles into a vesicle coat, controlling receptor-mediated endocytosis. To establish clathrin light chain (CLC) function in vivo, we engineered mice lacking CLCa, the major CLC isoform in B lymphocytes, generating animals with CLC-deficient B cells. In CLCa-null mice, the germinal centers have fewer B cells, and they are enriched for IgA-producing cells. This enhanced switch to IgA production in the absence of CLCa was attributable to increased transforming growth factor β receptor 2 (TGFβR2) signaling resulting from defective endocytosis. Internalization of C-X-C chemokine receptor 4 (CXCR4), but not CXCR5, was affected in CLCa-null B cells, and CLC depletion from cell lines affected endocytosis of the δ-opioid receptor, but not the β2-adrenergic receptor, defining a role for CLCs in the uptake of a subset of signaling receptors. This instance of clathrin subunit deletion in vertebrates demonstrates that CLCs contribute to clathrin’s role in vivo by influencing cargo selectivity, a function previously assigned exclusively to adaptor molecules.

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Section: Clc Depletion From Cell Lines Establishes Selectivity For DIsupporting

confidence: 65%

mentioning

confidence: 99%

Clathrin light chains’ role in selective endocytosis influences antibody isotype switching

Majeed

Evans

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…2C). An increase in a number of proteins of the endomembrane system was also identified in the absence of Atg7, such as clathrin heavy chain (26), two lysosomal proteins, and Atg12, an autophagy-related protein which when conjugated to Atg5 by Atg7 forms an integral part of autophagosomal membranes (27). Most importantly, this analysis revealed that mitochondrial proteins were consistently and preferentially detected in Atg7 −/− samples only, further confirming that in the absence of autophagy, peripheral blood cells have impaired removal of mitochondria.…”

Section: Resultsmentioning

confidence: 97%

Loss of autophagy in erythroid cells leads to defective removal of mitochondria and severe anemia in vivo

Mortensen

Ferguson

Edelmann

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

329

323

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Timely elimination of damaged mitochondria is essential to protect cells from the potential harm of disordered mitochondrial metabolism and release of proapoptotic proteins. In mammalian red blood cells, the expulsion of the nucleus followed by the removal of other organelles, such as mitochondria, are necessary differentiation steps. Mitochondrial sequestration by autophagosomes, followed by delivery to the lysosomal compartment for degradation (mitophagy), is a major mechanism of mitochondrial turnover. Here we show that mice lacking the essential autophagy gene Atg7 in the hematopoietic system develop severe anemia. Atg7 −/− erythrocytes accumulate damaged mitochondria with altered membrane potential leading to cell death. We find that mitochondrial loss is initiated in the bone marrow at the Ter119 + /CD71 High stage. Proteomic analysis of erythrocyte ghosts suggests that in the absence of autophagy other cellular degradation mechanisms are induced. Importantly, neither the removal of endoplasmic reticulum nor ribosomes is affected by the lack of Atg7. Atg7 deficiency also led to severe lymphopenia as a result of mitochondrial damage followed by apoptosis in mature T lymphocytes. Ex vivo short-lived hematopoietic cells such as monocytes and dendritic cells were not affected by the loss of Atg7. In summary, we show that the selective removal of mitochondria by autophagy, but not other organelles, during erythropoeisis is essential and that this is a necessary developmental step in erythroid cells.Atg7 | mitophagy | lymphopenia | cell death | reactive oxygen species

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“…Proteins were separated by 10% SDS-PAGE and blotted on HyBond nitrocellulose membranes (GE Healthcare), which were blocked for 1 h in TBS-T (50 mM Tris-HCl, pH 7.5, 150 mM NaCl, 0.1% Tween 20) containing 5% nonfat dry milk. Membranes were then incubated 3 h in 1% nonfat milk with the respective antibodies: m,hLDLR (1:1000, R&D Systems), hTfR (1:1000, BD Biosciences), hPCSK9 (1:2500) (10), hCLCa and b (1:10,000) (19), hARH (1:1000, Abcam), ␤-actin (1:5000, Sigma). Appropriate horseradish peroxidase-conjugated secondary antibodies (1:10,000, Sigma) were used for detection with enhanced chemiluminescence using the ECL plus kit (GE Healthcare).…”

Section: Methodsmentioning

confidence: 99%

“…chains CLCa and CLCb are not required for clathrin-mediated endocytosis but are critical for clathrin-mediated trafficking between the trans-Golgi network and the endosomal system (19). Accordingly, KD of both isoforms in HepG2 cells (KD CLCs ) resulted in the clustering of the cation-independent mannose 6-phosphate receptor, characteristic of disruption of the intracellular Golgi-lysosomal pathway (Fig.…”

Section: Disruption Of Intracellular Trafficking Increases Endogenousmentioning

confidence: 99%

Dissection of the Endogenous Cellular Pathways of PCSK9-induced Low Density Lipoprotein Receptor Degradation

Poirier

Mayer

Poupon

et al. 2009

Journal of Biological Chemistry

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237

185

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Elevated levels of plasma low density lipoprotein (LDL)-cholesterol, leading to familial hypercholesterolemia, are enhanced by mutations in at least three major genes, the LDL receptor (LDLR), its ligand apolipoprotein B, and the proprotein convertase PCSK9. Single point mutations in PCSK9 are associated with either hyperor hypocholesterolemia. Accordingly, PCSK9 is an attractive target for treatment of dyslipidemia. PCSK9 binds the epidermal growth factor domain A (EGF-A) of the LDLR and directs it to endosomes/ lysosomes for destruction. Although the mechanism by which PCSK9 regulates LDLR degradation is not fully resolved, it seems to involve both intracellular and extracellular pathways. Here, we show that clathrin light chain small interfering RNAs that block intracellular trafficking from the trans-Golgi network to lysosomes rapidly increased LDLR levels within HepG2 cells in a PCSK9-dependent fashion without affecting the ability of exogenous PCSK9 to enhance LDLR degradation. In contrast, blocking the extracellular LDLR endocytosis/degradation pathway by a 4-, 6-, or 24-h incubation of cells with Dynasore or an EGF-AB peptide or by knockdown of endogenous autosomal recessive hypercholesterolemia did not significantly affect LDLR levels. The present data from HepG2 cells and mouse primary hepatocytes favor a model whereby depending on the dose and/or incubation period, endogenous PCSK9 enhances the degradation of the LDLR both extraand intracellularly. Therefore, targeting either pathway, or both, would be an effective method to reduce PCSK9 activity in the treatment of hypercholesterolemia and coronary heart disease.

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Clathrin light chains function in mannose phosphate receptor trafficking via regulation of actin assembly

Abstract: endocytosis ͉ huntingtin-interacting protein ͉ trans-Golgi network

Cited by 79 publications

References 55 publications

Clathrin light chains’ role in selective endocytosis influences antibody isotype switching

Clathrin light chains’ role in selective endocytosis influences antibody isotype switching

Loss of autophagy in erythroid cells leads to defective removal of mitochondria and severe anemia in vivo

Dissection of the Endogenous Cellular Pathways of PCSK9-induced Low Density Lipoprotein Receptor Degradation

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