Presenilin-1 regulates the constitutive turnover of the fibronectin matrix in endothelial cells
© De Gasperi et al.; licensee BioMed Central Ltd. 2012
Received: 4 August 2012
Accepted: 13 December 2012
Published: 21 December 2012
Presenilin-1 (PS1) is a transmembrane protein first discovered because of its association with familial Alzheimer’s disease. Mice with null mutations in PS1 die shortly after birth exhibiting multiple CNS and non-CNS abnormalities. One of the most prominent features in the brains of PS1−/− embryos is a vascular dysgenesis that leads to multiple intracerebral hemorrhages. The molecular and cellular basis for the vascular dysgenesis in PS1−/− mice remains incompletely understood. Because the extracellular matrix plays key roles in vascular development we hypothesized that an abnormal extracellular matrix might be present in endothelial cells lacking PS1 and examined whether the lack of PS1 affects expression of fibronectin a component of the extracellular matrix known to be essential for vascular development.
We report that primary as well as continuously passaged PS1−/− endothelial cells contain more fibronectin than wild type cells and that the excess fibronectin in PS1−/− endothelial cells is incorporated into a fibrillar network. Supporting the in vivo relevance of this observation fibronectin expression was increased in microvascular preparations isolated from E14.5 to E18.5 PS1−/− embryonic brain. Reintroduction of PS1 into PS1−/− endothelial cells led to a progressive decrease in fibronectin levels showing that the increased fibronectin in PS1−/− endothelial cells was due to loss of PS1. Increases in fibronectin protein in PS1−/− endothelial cells could not be explained by increased levels of fibronectin RNA nor based on metabolic labeling studies by increased protein synthesis. Rather we show based on the rate of turnover of exogenously added biotinylated fibronectin that increased fibronectin in PS1−/− endothelial cells results from a slower degradation of the fibronectin fibrillar matrix on the cell surface.
These studies show that PS1 regulates the constitutive turnover of the fibronectin matrix in endothelial cells. These studies provide molecular clues that may help to explain the origin of the vascular dysgenesis that develops in PS1−/− embryonic mice.
KeywordsEndothelial cells Extracellular matrix Fibronectin Presenilin-1 Vascular development
Presenilin-1 is a polytopic transmembrane protein that was first discovered because of its association with familial Alzheimer’s disease [1, 2]. PS1 is highly conserved in evolution having homologues in organisms as distant as C. elegans, drosophila and lower chordates [3–5]. A related gene, presenilin-2 also exists and mutations in this gene also cause familial Alzheimer’s disease .
Within cells PS1 protein is located primarily in endoplasmic reticulum and Golgi membranes [6, 7]. However some protein is found in endosomes and on the surface of cells as well as in the nuclear membrane and at synaptic sites [8–10]. PS1 influences multiple molecular pathways being best known for its role as a component of the γ-secretase complex . However PS1 also interacts with other proteins in manners that do not involve γ-secretase cleavage such as PS1’s well-studied interaction with β-catenin in which PS1 controls β-catenin stability by favoring its stepwise phosphorylation leading to its degradation .
Mice with null mutations in PS1 die within 30 min after birth exhibiting multiple CNS and non-CNS abnormalities [12, 13]. One of the most prominent features in the developing brains is a vascular dysgenesis that is associated with multiple intracerebral hemorrhages [12–15]. The molecular and cellular basis for the vascular dysgenesis in PS1−/− mice remains incompletely understood. The extracellular matrix plays a key role in vascular development  which led us to hypothesize that components of the extracellular matrix might be altered by the absence of PS1.
Fibronectin is one key component of the extracellular matrix. Many extracellular matrix proteins depend on fibronectin for their incorporation into the matrix . Within the extracellular matrix, fibronectin supports cell adhesion in addition to playing functional roles in regulating growth factor  and integrin related signaling . Fibronectin is essential for vascular development and fibronectin null mutations in the mouse lead to embryonic lethality with severe vascular defects .
Here we report that PS1−/− endothelial cells contain more fibronectin than wild type cells. We further show that fibronectin accumulates in PS1−/− endothelial cells due to decreased turnover of the fibrillar fibronectin matrix. These studies demonstrate a critical role for PS1 in regulating the formation of the extracellular matrix by endothelial cells and may help to explain the basis for the vascular dysgenesis found in PS1−/− mice.
Genetically modified mice
The PS1−/− mice utilized were those generated by Shen et al. . Genotyping was performed as previously described . Heterozygous mice were mated to produce PS1−/− embryos with the day a vaginal plug was detected designated as E0.5. Pregnant female mice were euthanized with carbon dioxide and PS1−/− embryos were presumptively identified based on their gross dysmorphic appearance. A portion of the body was saved and used to isolate DNA and confirm genotypes. All protocols were approved by the Institutional Animal Care and Use Committee of the James J. Peters Department of Veterans Affairs Medical Center (Bronx, NY USA) and were conducted in conformance with Public Health Service policy on the humane care and use of laboratory animals and the NIH Guide for the Care and Use of Laboratory Animals.
Generation of wild type and PS1−/− endothelial cell cultures
Endothelial cells were prepared from E15.5 to E16.5 embryonic brains. To maximize the yield the entire brain was used to prepare cultures after removal of the meninges. Endothelial cell cultures were prepared as described previously . Cultures were continuously passaged on tissue culture dishes coated with murine collagen type IV (BD Biosciences, Franklin Lakes, NJ, USA) in endothelial cell growth medium (ECGM: DMEM-F12 supplemented with 10% heat-inactivated horse serum, 10% heat-inactivated fetal calf serum, 100 μg/ml endothelial cell growth supplement [BD Biosciences, Franklin Lakes, NJ, USA], and 100 μg/ml heparin). Continuous cell lines were established by continuously passing the cells at high density (1:2 split ratio) in ECGM.
Preparation of embryonic microvessel fractions
Embryos from PS1−/− and wild type littermate controls were collected at gestational ages ranging from E14.5 to 18.5. Brains were dissected, suspended in phosphate buffered saline (PBS) and mechanically dissociated with a fire-polished Pasteur pipette. The suspension was filtered through a 75 μm nylon mesh filter. The microvessels retained on the filter were extensively washed with cold PBS and collected by centrifugation. To increase yields two to three brains per genotype were pooled from each litter.
Endothelial cells were cultured on collagen IV coated slides and fixed with 4% paraformaldehyde/PBS at room temperature or with acetone/methanol (2:3 v/v) at −20°C. Immunostaining was performed as previously described  using the following antibodies: a rabbit polyclonal anti-fibronectin (1:400; Sigma Aldrich, St. Louis MO, USA), a rabbit polyclonal antibody against von Willebrand factor (1:400; Sigma Aldrich) and a rat monoclonal anti PECAM/CD31 (1:100; Millipore Billerica, MA USA) followed by appropriate Alexa-conjugated secondary antibodies (Invitrogen, Carlsbad, CA USA). Nuclei were counterstained with 1 μg/ml 4',6-diamidino-2-phenylindole (DAPI). When staining for biotinylated fibronectin, cell cultures were incubated with Alexa conjugated-streptavidin (1:300; Invitrogen). Images were acquired with a Zeiss Axioplan or a Zeiss 700 confocal microscope (Zeiss, Thornwood, NY USA). To quantitate levels of fibronectin expression random fields were photographed under the same exposure with a 20x lens on a Zeiss Axioplan microscope. Images were analyzed with Adobe Photoshop CS4 Extended v11.02 (Adobe Systems Incorporated, San Jose, CA USA) using the analysis tool. Results were expressed as fluorescence intensity/unit area/number of nuclei. Ten random fields containing approximately 100 cells were counted.
For immunohistochemistry E15.5 embryonic brains were collected, fixed overnight in 4% paraformaldehyde/PBS and stored in PBS until sectioning. 50 μm thick sections were cut on a Leica VT1000 Vibratome (Vienna, Austria). Sections were stained with the rabbit polyclonal anti-fibronectin antibody described above (1:400) and with biotin-labeled Bandeiraea (Griffonia) simplicifolia lectin (3μg/ml; BSI-B4, Sigma-Aldrich) as previously described . Sections were counterstained with DAPI.
Endothelial cell electroporation
Endothelial cells were trypsinized, washed with PBS and resuspended in RPMI/10% fetal calf serum (electroporation buffer). 400 μl aliquots containing approximately 3×105 cells were transferred to the electroporation cuvettes (BTX Harvard Apparatus, Holliston, MA USA). Plasmid DNA was added and the mixture chilled 10 min at 4°C. Electroporation was performed with an ECM 830 generator (BTX, Harvard Apparatus) using one 200-volt pulse applied for 40 msec. After a 5 min recovery at room temperature the cells were plated in ECGM. An expression ready plasmid containing human PS1 cDNA was obtained from Genecopeia (Rockville, MD USA).
Western blot analysis
Cells or embryonic vessel preparations were lysed in a buffer containing 50 mM Tris HCl pH 7.4, 150 mM NaCl, 1 mM EDTA, 1% Triton X-100, 0.5% Na deoxycholate, 0.5% SDS containing protease inhibitors (Halt, Pierce, Rockford IL USA) and phosphatase inhibitor cocktails 2 and 3 (Sigma-Aldrich). After a brief sonication, extracts were centrifuged at 14,000 rpm for 20 min and the supernatants collected. Protein concentration was determined with the BCA reagent as described by the manufacturer (Pierce). Western blotting was performed as previously described . The following antibodies were used: a rabbit polyclonal anti-fibronectin (1:4000; Sigma Aldrich), a rabbit monoclonal anti-vimentin (1:1500, Cell Signaling, Danvers, MA, USA), a mouse monoclonal antibody against the human PS1 N-terminal fragment (NT.1; 1:500; gift of Dr. Paul Mathews, Nathan Kline Institute, Orangeburg NY, USA) and a mouse monoclonal antibody against the PS1 C-terminal fragment (33B10, 1:1000; gift of Dr. Nikolaos Robakis, Icahn School of Medicine at Mount Sinai, New York, NY, USA). A rabbit polyclonal anti β-tubulin (1:5000; Abcam, Cambridge UK) was used as loading control.
Deoxycholate solubility assay
Deoxycholate (DOC) solubility was assessed as described in Wierzbicka-Patynowski et al. . Endothelial cells were grown in ECGM medium containing fibronectin-depleted serum that had been prepared by chromatography through gelatin-Sepharose . The cells were harvested after 48 hrs, lysed in DOC lysis buffer (2% Na deoxycholate, 20 mM Tris HCl pH 8.8, 2 mM EDTA, 2 mM iodoacetic acid and 2 mM N-ethylmaleimide) and the viscosity reduced by several passages though a 25g needle. The lysate was centrifuged at 14,000 rpm for 30 minutes and the supernatant saved as the DOC soluble fraction. The pellet (i.e. the DOC insoluble fraction) was washed once in DOC lysis buffer, resuspended in lysis buffer containing 1% SDS instead of 2% DOC and boiled for 5 minutes. Protein concentration was determined with the BCA reagent and the fractions were analyzed by Western blotting.
Purified bovine plasma fibronectin 0.5 mg; Sigma Aldrich was dialyzed against 0.5 M Na carbonate buffer, pH 8.5/0.15 M NaCl overnight at 4°C. NHS-Biotin (Pierce) was added (0.1 mg/ml) and the mixture incubated for 30 min and dialyzed overnight against Tris-buffered saline . Biotinylated fibronectin was added to cells at a concentration of 20 μg/ml. To determine the rate of degradation of exogenously supplied fibronectin endothelial cells were pulsed with biotinylated fibronectin (20 μg/ml) overnight. The cells were then washed with PBS and harvested (0 time point) or switched to FN-depleted ECGM medium and chased for 8 or 24 hrs at which time cells were washed with PBS and the DOC soluble and insoluble fractions were prepared. Samples were analyzed by Western blotting probed with streptavidin-HRP (1:1000; Jackson Immuno Research Laboratories, West Grow, PA USA) for 2 hrs and visualized with the ECL Prime reagent (GE Healthcare).
Fibronectin labeling and immunoprecipitation
Cells were incubated with Expre35S35S-protein labeling mix (Perkin-Elmer, Waltham MA, USA) in cysteine/methionine free medium for different time intervals. At each time point the medium was collected and the cells were washed once with PBS and harvested. DOC soluble and insoluble fractions were prepared as described above. The samples were precleared with Agarose beads (Pierce) for 1 hr. Fibronectin was immunoprecipitated by addition of 2.0 μg of anti-fibronectin antibody (see above). After overnight incubation at 4°C, 20 μl of protein A/G slurry (Pierce) was added to capture the immune complexes. The beads were washed 3 times with 25 mM Tris HCl pH 7.4, 0.15 NaCl, 1mM EDTA, 1% NP-40, 5% glycerol and the bound proteins eluted by addition of reducing sample buffer. The eluted proteins were boiled for 10 min and loaded onto a 7.5% SDS-PAGE gel. Gels were fixed for 30 min with isopropanol/water/acetic acid 25/65/10 (v/v/v), and then treated with Amplify reagent (GE Healthcare, Piscatawy, NJ USA) for 30 min, dried and exposed to film.
RNA isolation and quantitative PCR (qPCR) analysis
Total RNA was isolated using the Rnaeasy kit (Ambion, Austin, TX, USA) according to the manufacturer’s instructions and treated with the DNA free reagent (Ambion) to remove any residual genomic DNA contamination. 0.5-1μg of RNA was reverse transcribed using the High Capacity cDNA reverse transcription kit (Applied Biosystems, Foster City, CA USA). qPCR analysis was performed using predesigned Taqman gene expression assays (Applied Biosystems) for the selected targets as described previously . Normalization was carried out using the geometric means of three genes: peptidylprolyl isomerase A (Ppia), β-glucuronidase (Gusb) and β-actin.
All data are presented as mean ± the standard error of the mean. Equality of variance was assessed using the Levene test. Comparisons were made using unpaired t tests (Student’s t if the variances did not differ significantly, p > 0.05, by Levene’s test; otherwise using the Welch correction for unequal variances). Pearson correlations were also utilized. Statistical tests were performed using the program GraphPad Prism 5.0 (GraphPad Software, San Diego, CA USA) or SPSS 20.0 (SPSS, Chicago, IL USA).
PS1−/− endothelial cells contain more fibronectin than wild type endothelial cells
Levels of fibronectin RNA in PS1−/− endothelial cells
More fibrillar fibronectin is present in PS1−/− endothelial cells
Synthesis of fibronectin is not increased in PS1−/− endothelial cells
Increased assembly of a fibronectin matrix on the surface of PS1−/− endothelial cells
Turnover of biotinylated fibronectin is reduced in PS1−/− endothelial cells
Fibronectin is a modular protein that is derived from a single gene which can be alternatively spliced into 20 possible monomeric forms in man and up to 12 in mouse . Fibronectin exists in a cellular form that is present in tissues and assembled into a fibrillar matrix, as well as a plasma form that is produced by the liver and secreted into the blood where it is soluble and nonfibrillar . The assembled fibronectin matrix binds other components of the extracellular matrix . Within the extracellular matrix, fibronectin supports cell adhesion but plays other functional roles as well such as its role in regulating activation of latent complexes containing the transforming growth factor-β [18, 28].
Here we show that PS1 regulates fibronectin levels in endothelial cells by modulating the constitutive turnover of the fibronectin matrix. PS1−/− endothelial cells contained more fibronectin protein that assembled into a fibrillar network. The increased fibronectin protein could not be explained by altered levels of fibronectin RNA nor by increased protein synthesis. Rather the increased fibronectin in PS1−/− endothelial cells resulted from a slower rate of degradation of the fibrillar fibronectin matrix assembled on the cell surface.
Fibronectin matrix assembly begins with secretion of soluble fibronectin dimers ( reviewed in  ) that bind to integrin receptors on the cell surface. Then in a process that is still incompletely understood fibronectin to fibronectin associations occur that lead to fibril formation and production of a fibrillar network . Integrins are a family of cell surface receptors composed of non-covalently linked heterodimers composed of α and β subunits [29, 30]. Integrin α5β1 is the major fibronectin receptor although other integrins can perform this function in some circumstances [31, 32]. Integrins signal through a dynamic spatially and temporally controlled process that involves assembly of multiprotein complexes through their cytoplasmic tails .
Following fibronectin binding to an integrin receptor, bound fibronectin is first diffusely localized on the cell surface . Fibronectin binding promotes receptor clustering and the dimeric fibronectin becomes organized into short fibrils that are initially DOC soluble . Thin fibrils lengthen and are converted into a DOC insoluble form.
Integrin receptor activation further leads to the cytoplasmic domains of integrins becoming associated with and activating the cytoskeleton. During this process complexes containing α5β1 integrin, focal adhesion kinase (FAK), vinculin, and paxillin form at sites of fibronectin fibril assembly leading to activation of FAK, the recruitment and activation of Src family kinases and activation of the phosphoinositide 3-kinase (PI3K) pathway among others [33, 34].
Where PS1 is acting in the molecular events that regulate fibronectin matrix turnover is unclear. PS1 has been reported to affect maturation of the β1 integrin subunit in fibroblasts . However, in exploring levels of integrins in PS1−/− endothelial cells we have not found any consistent changes in levels of the α5 or β1 subunits (unpublished observations). Functionally PS1 is best known for its role as a component of the γ-secretase complex which is known to cleave more than 60 transmembrane proteins . Therefore PS1 could be regulating fibronectin turnover if it affected signaling through integrin receptors. Integrins are transmembrane proteins made of α/β heterodimers with each subunit having a large extracellular domain, a single transmembrane helix and a short cytoplasmic segment . There is currently no evidence that integrin subunits are cleaved by γ-secretase. However, PS1 influences some of the known pathways regulated by integrin signaling. For example PS1 has been reported to enhance signaling through the PI3K/Akt pathway by associating with the p85 regulatory subunit of PI3K [37, 38] although why this interaction should affect turnover of the fibronectin matrix is unclear. Fibronectin matrix turnover also occurs through a caveolin-1 dependent process  and caveolin-1 dependent trafficking has been reported to be affected by the absence of PS1  providing another mechanism whereby PS1 could affect fibronectin matrix remodeling.
Future studies will be needed to determine how PS1 affects remodeling of the fibronectin matrix at the cell surface. However whatever its mechanism of action, these studies show that PS1 is essential for the constitutive remodeling of the fibronectin matrix in endothelial cells. The extracellular matrix plays crucial roles in the development and function of the cerebral vasculature  and fibronectin is essential for normal vasculogenesis with the absence of fibronectin leading to severe embryonic vascular defects . Whether ineffective remodeling of the fibronectin matrix may help to explain the vascular dysgenesis in the brains of PS1−/− embryos is as yet unclear. However, these studies suggest molecular clues to the origins of the vascular dysgenesis found in PS1−/− embryonic mice that can be explored in future studies.
central nervous system
C terminal fragment
Dulbecco's Modified Eagle Medium/Ham’s F12
endothelial cell growth medium
Nonidet-P40 (octyl phenoxylpolyethoxylethanol)
N terminal fragment
phosphoinositide 3 kinase
phosphate buffered saline
polymerase chain reaction
platelet endothelial cell adhesion molecule
peptidylprolyl isomerase A
quantitative polymerase chain reaction
Roswell Park Memorial Institute medium
sodium dodecyl sulfate polyacrylamide gel electrophoresis
This work was supported by a Merit Award from the Department of Veterans Affairs (5I01BX000342-02). We thank Drs. Paul Mathews and Nikolaos Robakis for gifts of antibodies.
- Lleo A, Berezovska O, Growdon JH, Hyman BT: Clinical, pathological, and biochemical spectrum of Alzheimer disease associated with PS-1 mutations. Am J Geriatr Psychiatry. 2004, 12 (2): 146-156.PubMedView ArticleGoogle Scholar
- De Strooper B, Annaert W: Novel research horizons for presenilins and gamma-secretases in cell biology and disease. Annu Rev Cell Dev Biol. 2010, 26: 235-260. 10.1146/annurev-cellbio-100109-104117.PubMedView ArticleGoogle Scholar
- Levitan D, Greenwald I: Facilitation of lin-12-medlated signalling by sel-12, a Caenorhabditis elegans S182 Alzhelmer's disease gene. Nature. 1995, 377: 351-10.1038/377351a0.PubMedView ArticleGoogle Scholar
- Boulianne GL, Livne-Bar I, Humphreys JM, Liang Y, Lin C, Rogaev E, St. George-Hyslop P: Cloning and characterization of the Drosophila presenilin homologue. Neuroreport. 1997, 8 (4): 1025-1029. 10.1097/00001756-199703030-00041.PubMedView ArticleGoogle Scholar
- Martinez-Mir A, Canestro C, Gonzalez-Duarte R, Albalat R: Characterization of the amphioxus presenilin gene in a high gene-density genomic region illustrates duplication during the vertebrate lineage. Gene. 2001, 279 (2): 157-164. 10.1016/S0378-1119(01)00751-X.PubMedView ArticleGoogle Scholar
- Kovacs DM, Fausett HJ, Page KJ, Kim TW, Moir RD, Merriam DE, Hollister RD, Hallmark OG, Mancini R, Felsenstein KM: Alzheimer-associated presenilins 1 and 2: neuronal expression in brain and localization to intracellular membranes in mammalian cells. Nat Med. 1996, 2 (2): 224-229. 10.1038/nm0296-224.PubMedView ArticleGoogle Scholar
- De Strooper B, Beullens M, Contreras B, Levesque L, Craessaerts K, Cordell B, Moechars D, Bollen M, Fraser P, George-Hyslop PS: Phosphorylation, subcellular localization, and membrane orientation of the Alzheimer's disease-associated presenilins. J Biol Chem. 1997, 272 (6): 3590-3598. 10.1074/jbc.272.6.3590.PubMedView ArticleGoogle Scholar
- Rechards M, Xia W, Oorschot VM, Selkoe DJ, Klumperman J: Presenilin-1 exists in both pre- and post-Golgi compartments and recycles via COPI-coated membranes. Traffic. 2003, 4 (8): 553-565. 10.1034/j.1600-0854.2003.t01-1-00114.x.PubMedView ArticleGoogle Scholar
- Georgakopoulos A, Marambaud P, Efthimiopoulos S, Shioi J, Cui W, Li HC, Schutte M, Gordon R, Holstein GR, Martinelli G: Presenilin-1 forms complexes with the cadherin/catenin cell-cell adhesion system and is recruited to intercellular and synaptic contacts. Mol Cell. 1999, 4 (6): 893-902. 10.1016/S1097-2765(00)80219-1.PubMedView ArticleGoogle Scholar
- Li J, Xu M, Zhou H, Ma J, Potter H: Alzheimer presenilins in the nuclear membrane, interphase kinetochores, and centrosomes suggest a role in chromosome segregation. Cell. 1997, 90 (5): 917-927. 10.1016/S0092-8674(00)80356-6.PubMedView ArticleGoogle Scholar
- Hass MR, Sato C, Kopan R, Zhao G: Presenilin: RIP and beyond. Semin Cell Dev Biol. 2009, 20 (2): 201-210. 10.1016/j.semcdb.2008.11.014.PubMedPubMed CentralView ArticleGoogle Scholar
- Shen J, Bronson RT, Chen DF, Xia W, Selkoe DJ, Tonegawa S: Skeletal and CNS defects in Presenilin-1-deficient mice. Cell. 1997, 89 (4): 629-639. 10.1016/S0092-8674(00)80244-5.PubMedView ArticleGoogle Scholar
- Wong PC, Zheng H, Chen H, Becher MW, Sirinathsinghji DJ, Trumbauer ME, Chen HY, Price DL, Van der Ploeg LH, Sisodia SS: Presenilin 1 is required for Notch1 and DII1 expression in the paraxial mesoderm. Nature. 1997, 387 (6630): 288-292. 10.1038/387288a0.PubMedView ArticleGoogle Scholar
- Nakajima M, Yuasa S, Ueno M, Takakura N, Koseki H, Shirasawa T: Abnormal blood vessel development in mice lacking presenilin-1. Mech Dev. 2003, 120 (6): 657-667. 10.1016/S0925-4773(03)00064-9.PubMedView ArticleGoogle Scholar
- Wen PH, De Gasperi R, Sosa MA, Rocher AB, Friedrich VL, Hof PR, Elder GA: Selective expression of presenilin 1 in neural progenitor cells rescues the cerebral hemorrhages and cortical lamination defects in presenilin 1-null mutant mice. Development. 2005, 132 (17): 3873-3883. 10.1242/dev.01946.PubMedPubMed CentralView ArticleGoogle Scholar
- del Zoppo GJ, Milner R: Integrin-matrix interactions in the cerebral microvasculature. Arterioscler Thromb Vasc Biol. 2006, 26 (9): 1966-1975. 10.1161/01.ATV.0000232525.65682.a2.PubMedView ArticleGoogle Scholar
- Singh P, Carraher C, Schwarzbauer JE: Assembly of fibronectin extracellular matrix. Annu Rev Cell Dev Biol. 2010, 26: 397-419. 10.1146/annurev-cellbio-100109-104020.PubMedPubMed CentralView ArticleGoogle Scholar
- Dallas SL, Sivakumar P, Jones CJ, Chen Q, Peters DM, Mosher DF, Humphries MJ, Kielty CM: Fibronectin regulates latent transforming growth factor-beta (TGF beta) by controlling matrix assembly of latent TGF beta-binding protein-1. J Biol Chem. 2005, 280 (19): 18871-18880. 10.1074/jbc.M410762200.PubMedView ArticleGoogle Scholar
- Astrof S, Hynes RO: Fibronectins in vascular morphogenesis. Angiogenesis. 2009, 12 (2): 165-175. 10.1007/s10456-009-9136-6.PubMedPubMed CentralView ArticleGoogle Scholar
- De Gasperi R, Gama Sosa MA, Dracheva S, Elder GA: Presenilin-1 regulates induction of hypoxia inducible factor-1alpha: altered activation by a mutation associated with familial Alzheimer's disease. Mol Neurodegener. 2010, 5 (1): 38-10.1186/1750-1326-5-38.PubMedPubMed CentralView ArticleGoogle Scholar
- Gama Sosa MA, De Gasperi R, Rocher AB, Perez GM, Simons K, Cruz DE, Hof PR, Elder GA: Interactions of primary neuroepithelial progenitor and brain endothelial cells: distinct effect on neural progenitor maintenance and differentiation by soluble factors and direct contact. Cell Res. 2007, 17 (7): 619-626. 10.1038/cr.2007.53.PubMedView ArticleGoogle Scholar
- Wierzbicka-Patynowski I, Mao Y, Schwarzbauer J: Analysis of Fibronectin Matrix Assembly. Curr Protoc Cell Biol. 2004, Unit 10.12 (Supplement 25): 10.12.10-10.12.11.Google Scholar
- Pankov R, Yamada K: Quantification of matrix assembly using biotinylated fibronectin. Curr Protoc Cell Biol. 2004, Unit 10.13 (Supplement 25): 10.13.11-10.13.19.Google Scholar
- Choi MG, Hynes RO: Biosynthesis and processing of fibronectin in NIL.8 hamster cells. J Biol Chem. 1979, 254 (23): 12050-12055.PubMedGoogle Scholar
- Sechler JL, Takada Y, Schwarzbauer JE: Altered rate of fibronectin matrix assembly by deletion of the first type III repeats. J Cell Biol. 1996, 134 (2): 573-583. 10.1083/jcb.134.2.573.PubMedView ArticleGoogle Scholar
- Mao Y, Schwarzbauer JE: Fibronectin fibrillogenesis, a cell-mediated matrix assembly process. Matrix Biol. 2005, 24 (6): 389-399. 10.1016/j.matbio.2005.06.008.PubMedView ArticleGoogle Scholar
- Dallas SL, Chen Q, Sivakumar P: Dynamics of assembly and reorganization of extracellular matrix proteins. Curr Top Dev Biol. 2006, 75: 1-24.PubMedView ArticleGoogle Scholar
- Fontana L, Chen Y, Prijatelj P, Sakai T, Fassler R, Sakai LY, Rifkin DB: Fibronectin is required for integrin alphavbeta6-mediated activation of latent TGF-beta complexes containing LTBP-1. FASEB J. 2005, 19 (13): 1798-1808. 10.1096/fj.05-4134com.PubMedView ArticleGoogle Scholar
- Harburger DS, Calderwood DA: Integrin signalling at a glance. J Cell Sci. 2009, 122 (Pt 2): 159-163.PubMedPubMed CentralView ArticleGoogle Scholar
- Legate KR, Wickstrom SA, Fassler R: Genetic and cell biological analysis of integrin outside-in signaling. Genes Dev. 2009, 23 (4): 397-418. 10.1101/gad.1758709.PubMedView ArticleGoogle Scholar
- Larsen M, Artym VV, Green JA, Yamada KM: The matrix reorganized: extracellular matrix remodeling and integrin signaling. Curr Opin Cell Biol. 2006, 18 (5): 463-471. 10.1016/j.ceb.2006.08.009.PubMedView ArticleGoogle Scholar
- Leiss M, Beckmann K, Giros A, Costell M, Fassler R: The role of integrin binding sites in fibronectin matrix assembly in vivo. Curr Opin Cell Biol. 2008, 20 (5): 502-507. 10.1016/j.ceb.2008.06.001.PubMedView ArticleGoogle Scholar
- Hu P, Luo BH: Integrin bidirectional signaling across the plasma membrane. J Cell Physiol. 2013, 228 (2): 306-312. 10.1002/jcp.24154.PubMedView ArticleGoogle Scholar
- Wehrle-Haller B: Assembly and disassembly of cell matrix adhesions. Curr Opin Cell Biol. 2012, 24 (5): 569-581. 10.1016/j.ceb.2012.06.010.PubMedView ArticleGoogle Scholar
- Zou K, Hosono T, Nakamura T, Shiraishi H, Maeda T, Komano H, Yanagisawa K, Michikawa M: Novel role of presenilins in maturation and transport of integrin beta 1. Biochemistry. 2008, 47 (11): 3370-3378. 10.1021/bi7014508.PubMedView ArticleGoogle Scholar
- Hynes RO: Integrins: bidirectional, allosteric signaling machines. Cell. 2002, 110 (6): 673-687. 10.1016/S0092-8674(02)00971-6.PubMedView ArticleGoogle Scholar
- Baki L, Shioi J, Wen P, Shao Z, Schwarzman A, Gama-Sosa M, Neve R, Robakis NK: PS1 activates PI3K thus inhibiting GSK-3 activity and tau overphosphorylation: effects of FAD mutations. EMBO J. 2004, 23 (13): 2586-2596. 10.1038/sj.emboj.7600251.PubMedPubMed CentralView ArticleGoogle Scholar
- Weihl CC, Ghadge GD, Kennedy SG, Hay N, Miller RJ, Roos RP: Mutant presenilin-1 induces apoptosis and downregulates Akt/PKB. J Neurosci. 1999, 19 (13): 5360-5369.PubMedGoogle Scholar
- Sottile J, Chandler J: Fibronectin matrix turnover occurs through a caveolin-1-dependent process. Mol Biol Cell. 2005, 16 (2): 757-768.PubMedPubMed CentralView ArticleGoogle Scholar
- Wood DR, Nye JS, Lamb NJ, Fernandez A, Kitzmann M: Intracellular retention of caveolin 1 in presenilin-deficient cells. J Biol Chem. 2005, 280 (8): 6663-6668. 10.1074/jbc.M410332200.PubMedView ArticleGoogle Scholar
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