Functional genomic screen identifies novel mediators of collagen uptake

Lee, Ting‐Hein; McKleroy, William; Khalifeh-Soltani, Amin; Sakuma, Stephen; Lazarev, Stanislav; Riento, Kirsi; Nishimura, Stephen L.; Nichols, Benjamin J.; Atabai, Kamran

doi:10.1091/mbc.e13-07-0382

Cited by 28 publications

(33 citation statements)

References 56 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Furthermore, our finding that FAP ϩ fibroblasts more effectively internalize collagen compared with FAP-null cells confirms an important functional role for the protein in fibrogenesis. Our data are supported by a recent independent study where a genome-wide RNA interference screen in Drosophila S2 cells identified FAP as one of 22 candidate genes associated with increased collagen uptake (73). Finally, our data showing that FAP expression appears to modulate TGF-␤-mediated myofibroblast differentiation suggests that FAP may be very important in regulating the fibrogenic response after lung injury.…”

Section: Discussionsupporting

confidence: 86%

Fibroblast Activation Protein (FAP) Accelerates Collagen Degradation and Clearance from Lungs in Mice

Fan

Zhu

et al. 2016

Journal of Biological Chemistry

View full text Add to dashboard Cite

Idiopathic pulmonary fibrosis is a disease characterized by progressive, unrelenting lung scarring, with death from respiratory failure within 2-4 years unless lung transplantation is performed. New effective therapies are clearly needed. Fibroblast activation protein (FAP) is a cell surface-associated serine protease up-regulated in the lungs of patients with idiopathic pulmonary fibrosis as well as in wound healing and cancer. We postulate that FAP is not only a marker of disease but influences the development of pulmonary fibrosis after lung injury. In two different models of pulmonary fibrosis, intratracheal bleomycin instillation and thoracic irradiation, we find increased mortality and increased lung fibrosis in FAP-deficient mice compared with wild-type mice. Lung extracellular matrix analysis reveals accumulation of intermediate-sized collagen fragments in FAPdeficient mouse lungs, consistent with in vitro studies showing that FAP mediates ordered proteolytic processing of matrix metalloproteinase (MMP)-derived collagen cleavage products. FAP-mediated collagen processing leads to increased collagen internalization without altering expression of the endocytic collagen receptor, Endo180. Pharmacologic FAP inhibition decreases collagen internalization as expected. Conversely, restoration of FAP expression in the lungs of FAP-deficient mice decreases lung hydroxyproline content after intratracheal bleomycin to levels comparable with that of wild-type controls. Our findings indicate that FAP participates directly, in concert with MMPs, in collagen catabolism and clearance and is an important factor in resolving scar after injury and restoring lung homeostasis. Our study identifies FAP as a novel endogenous regulator of fibrosis and is the first to show FAP's protective effects in the lung.Idiopathic pulmonary fibrosis, the most common of the idiopathic interstitial pneumonias, is characterized by inexorable progressive lung injury and scarring, with eventual death within 2-4 years from the time of diagnosis in the absence of lung transplantation (1). The etiology of the disease is poorly understood, and current Food and Drug Administration-approved treatments have only limited impact on the course of the disease (2-4).Fibroblast activation protein (FAP, 2 also known as seprase) is a 95-kDa cell surface, type II integral serine protease belonging to the post-proline dipeptidyl aminopeptidase (DPP) family (5) that is specifically induced on lung fibroblasts in patients with idiopathic pulmonary fibrosis, in particular at the leading edge of fibrosis (6). The DPP family of serine proteases cleaves amino-terminal dipeptides from polypeptides with L-proline or L-alanine at the penultimate position. FAP is unique in that it displays additional in vitro endopeptidase (7), gelatinase, and potentially collagenase activity (8,9). FAP expression is restricted, occurring at high levels on mesenchymal cells during embryogenesis (10) and then is repressed shortly after birth. In conditions associated with matrix remodeling...

show abstract

Section: Discussionsupporting

confidence: 86%

Fibroblast Activation Protein (FAP) Accelerates Collagen Degradation and Clearance from Lungs in Mice

Fan

Zhu

et al. 2016

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…Resuspended cells were then stained with PE-conjugated anti-CD45 and analyzed for CD45 and FITC by flow cytometry as above. In some experiments, cell surface collagen-FITC was quenched with trypan blue (200 µg/mL) prior to flow cytometry analysis as previously described(42–44). …”

Section: Methodsmentioning

confidence: 99%

Fibrocytes Are Not an Essential Source of Type I Collagen during Lung Fibrosis

Kleaveland

Velikoff

Yang

et al. 2014

The Journal of Immunology

View full text Add to dashboard Cite

Progressive fibrosis involves accumulation of activated collagen producing mesenchymal cells. Fibrocytes are hematopoietic-derived cells with mesenchymal features that potentially have a unique and critical function during fibrosis. Fibrocytes have been proposed as an important direct contributor of type I collagen deposition during fibrosis based largely on fate-mapping studies. To determine the functional contribution of hematopoietic cell-derived type I collagen to fibrogenesis we utilize a double transgenic system to specifically delete the type I collagen gene across a broad population of hematopoietic cells. These mice develop a robust fibrotic response similar to littermate genotype control mice injured with bleomycin indicating that fibrocytes are not a necessary source of type I collagen. Using collagen-promoter GFP mice we find that fibrocytes express type I collagen. However, fibrocytes with confirmed deletion of the type I collagen gene have readily detectable intracellular type I collagen indicating that uptake of collagen from neighboring cells account for much of the fibrocyte collagen. Collectively these results clarify several seemingly conflicting reports regarding the direct contribution of fibrocytes to collagen deposition.

show abstract

“…Since then, other protein cargos the UFIT pathway were identified, such as transmembrane and GPI-anchor proteins [9,[78][79][80][81][82][83][84] and extracellular proteins [85,86] (Table 3). Most of them can enter into the cell through clathrin-mediated endocytosis or other clathrin-independent pathways, such as macro-pinocytosis.…”

Section: Flotillin-mediated Endocytosis a Vesicular Trafficking Pathmentioning

confidence: 99%

Flotillin membrane domains in cancer

Gauthier-Rouvière

Bodin

Comunale

et al. 2020

Cancer Metastasis Rev

View full text Add to dashboard Cite

Flotillins 1 and 2 are two ubiquitous, highly conserved homologous proteins that assemble to form heterotetramers at the cytoplasmic face of the plasma membrane in cholesterol-and sphingolipid-enriched domains. Flotillin heterotetramers can assemble into large oligomers to form molecular scaffolds that regulate the clustering of at the plasma membrane and activity of several receptors. Moreover, flotillins are upregulated in many invasive carcinomas and also in sarcoma, and this is associated with poor prognosis and metastasis formation. When upregulated, flotillins promote plasma membrane invagination and induce an endocytic pathway that allows the targeting of cargo proteins in the late endosomal compartment in which flotillins accumulate. These late endosomes are not degradative, and participate in the recycling and secretion of protein cargos. The cargos of this Upregulated Flotillin-Induced Trafficking (UFIT) pathway include molecules involved in signaling, adhesion, and extracellular matrix remodeling, thus favoring the acquisition of an invasive cellular behavior leading to metastasis formation. Thus, flotillin presence from the plasma membrane to the late endosomal compartment influences the activity, and even modifies the trafficking and fate of key protein cargos, favoring the development of diseases, for instance tumors. This review summarizes the current knowledge on flotillins and their role in cancer development focusing on their function in cellular membrane remodeling and vesicular trafficking regulation.

show abstract

Functional genomic screen identifies novel mediators of collagen uptake

Abstract: Novel mediators of cell-mediated collagen turnover are identified through an RNAi screen targeting Drosophila genes with metazoan orthologues. Flotillin genes are key regulators of collagen turnover in mammalian cells and work by stabilizing expression of collagen endocytic receptors.

Cited by 28 publications

References 56 publications

Fibroblast Activation Protein (FAP) Accelerates Collagen Degradation and Clearance from Lungs in Mice

Fibroblast Activation Protein (FAP) Accelerates Collagen Degradation and Clearance from Lungs in Mice

Fibrocytes Are Not an Essential Source of Type I Collagen during Lung Fibrosis

Flotillin membrane domains in cancer

Contact Info

Product

Resources

About