Binding of Urokinase-type Plasminogen Activator Receptor (uPAR) to the Mannose 6-Phosphate/Insulin-like Growth Factor II Receptor

Kreiling, Jodi L.; Byrd, James C.; Deisz, Robert J.; Mizukami, Ikuko F.; Todd, Robert F.; MacDonald, Richard G.

doi:10.1074/jbc.m302249200

Cited by 32 publications

(18 citation statements)

References 49 publications

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“…1C). The urokinase receptor (uPAR), a glycophosphatidylinositol-anchored protein that is associated with membrane lipid rafts and abundantly expressed in PC-3 cells (19), was present exclusively in the floating, nonnuclear fractions ( Fig. 1C), indicating the absence of significant cell membrane contamination of the nuclear fractions.…”

Section: Resultsmentioning

confidence: 99%

PTOV1 Enables the Nuclear Translocation and Mitogenic Activity of Flotillin-1, a Major Protein of Lipid Rafts

Santamaría

Castellanos

Gómez

et al. 2005

Molecular and Cellular Biology

104

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PTOV1 is a mitogenic protein that shuttles between the nucleus and the cytoplasm in a cell cycle-dependent manner. It consists of two homologous domains arranged in tandem that constitute a new class of protein modules. We show here that PTOV1 interacts with the lipid raft protein flotillin-1, with which it copurifies in detergent-insoluble floating fractions. Flotillin-1 colocalized with PTOV1 not only at the plasma membrane but, unexpectedly, also in the nucleus, as demonstrated by immunocytochemistry and subcellular fractionation of endogenous and exogenous flotillin-1. Flotillin-1 entered the nucleus concomitant with PTOV1, shortly before the initiation of the S phase. Protein levels of PTOV1 and flotillin-1 oscillated during the cell cycle, with a peak in S. Depletion of PTOV1 significantly inhibited nuclear localization of flotillin-1, whereas depletion of flotillin-1 did not affect nuclear localization of PTOV1. Depletion of either protein markedly inhibited cell proliferation under basal conditions. Overexpression of PTOV1 or flotillin-1 strongly induced proliferation, which required their localization to the nucleus, and was dependent on the reciprocal protein. These observations suggest that PTOV1 assists flotillin-1 in its translocation to the nucleus and that both proteins are required for cell proliferation.PTOV1 was identified as a novel gene and protein during a differential display screening for gene expression in prostate cancer (4). PTOV1 is overexpressed in 71% of prostate carcinomas and in 80% of samples with prostate intraepithelial neoplasia, while it its barely detectable in normal prostate epithelium (34). In an independent study, PTOV1 was also found to be one of the genes most discriminant between normal and carcinomatous prostate (44). This gene codes for a protein that consists of two highly related sequence blocks arranged in tandem that are conserved in humans, rodents, and flies (4). The PTOV domain does not resemble any other protein motif described so far. A PTOV domain is also present in another protein, PTOV2 (4), later identified as ARC92, a component of transcriptional coregulator multisubunit complexes (28). Recently, PTOV2/ARC92, renamed as ACID-1, has been identified as a critical protein of Mediator complexes for the recruitment of activators to the basal transcriptional machinery (26). We have used yeast two-hybrid screenings to search for interaction partners of PTOV1, yielding a specific interaction with the lipid raft-associated protein flotillin-1 (5). Lipid rafts are specialized membrane microdomains enriched in glycosphingolipids, cholesterol, and glycosylphosphatidylinositol-anchored proteins (36). It is now believed that lipid rafts represent a central feature of cellular organization crucial for membrane trafficking events and for specific signaling cascades (36). Ubiquitous markers of lipid rafts are proteins of the Reggie/flotillin family (36, 38). Reggie-1 and Reggie-2, whose human orthologues are flotillin-2 and flotillin-1, respectively, were originally ide...

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Section: Resultsmentioning

confidence: 99%

PTOV1 Enables the Nuclear Translocation and Mitogenic Activity of Flotillin-1, a Major Protein of Lipid Rafts

Santamaría

Castellanos

Gómez

et al. 2005

Molecular and Cellular Biology

104

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“…The luminal CDMPR monomer contains a single Man-6-P binding site while two of the repeating units on the CIMPR contain the high affinity binding sites (domains 3 and 9) and domain 11 contains the IGF2 binding site. The CIMPR may also bind urokinase-type plasminogen activator receptor at a site distinct from the Man-6-P and IGF2 binding sites (54), but this is controversial (55). Given the multiple domains of the CIMPR, it is possible that there are additional, as yet unidentified, ligands for this receptor.…”

Section: Discussionmentioning

confidence: 99%

Proteomics Analysis of Serum from Mutant Mice Reveals Lysosomal Proteins Selectively Transported by Each of the Two Mannose 6-Phosphate Receptors

Qian¹,

Sleat²,

Zheng³

et al. 2008

Molecular & Cellular Proteomics

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Most mammalian cells contain two types of mannose 6-phosphate (Man-6-P) receptors (MPRs): the 300 kDa cation-independent (CI) MPR and 46 kDa cation-dependent (CD) MPR. The two MPRs have overlapping function in intracellular targeting of newly synthesized lysosomal proteins, but both are required for efficient targeting. Despite extensive investigation, the relative roles and specialized functions of each MPR in targeting of specific proteins remain questions of fundamental interest. One possibility is that most Man-6-P glycoproteins are transported by both MPRs, but there may be subsets that are preferentially transported by each. To investigate this, we have conducted a proteomics analysis of serum from mice lacking either MPR with the reasoning that lysosomal proteins that are selectively transported by a given MPR should be preferentially secreted into the bloodstream in its absence. We purified and identified Man-6-P glycoproteins and glycopeptides from wild-type, CDMPRdeficient, and CIMPR-deficient mouse serum and found both lysosomal proteins and proteins not currently thought to have lysosomal function. Different mass spectrometric approaches (spectral count analysis of nanospray LC-MS/MS experiments on unlabeled samples and LC-MALDI/TOF/TOF experiments on iTRAQ-labeled samples) revealed a number of proteins that appear specifically elevated in serum from each MPR-deficient mouse. Man-6-P glycoforms of cellular repressor of E1A-stimulated genes 1, tripeptidyl peptidase I, and heparanase were elevated in absence of the CDMPR and Man-6-P glycoforms of alpha-mannosidase B1, cathepsin D, and prosaposin were elevated in the absence of the CIMPR. Results were confirmed by Western blot analyses for select proteins. This study provides a comparison of different quantitative mass spectrometric approaches and provides the first report of proteins whose cellular targeting appears to be MPR-selective under physiological conditions.

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“…It should be noted that IGF2R may serve other functions in addition to acting as a negative regulator of IGF2 ligand bioavailability [57]. For example, in other cell types IGF2R can bind urokinase-type plasminogen activator receptor and plasminogen [58,59], and it may be a receptor for retinoic acid [60]. Whether these other functions of the IGF2R are operative in ovarian tissue or granulosa cells in particular will require further elucidation.…”

Section: Spicer and Aadmentioning

confidence: 99%

Insulin-Like Growth Factor (IGF) 2 Stimulates Steroidogenesis and Mitosis of Bovine Granulosa Cells Through the IGF1 Receptor: Role of Follicle-Stimulating Hormone and IGF2 Receptor1

Spicer

Aad

2007

Biology of Reproduction

128

101

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Little is known regarding the role of insulin-like growth factor 2 (IGF2) and the regulation of the IGF2 receptor (IGF2R) during follicular development. Granulosa cells were collected from small (1-5 mm) and large (8-22 mm) bovine follicles and were treated with IGF2 for 1-2 days in serum-free medium, and steroid production, cell proliferation, specific 125 I-IGF2 binding, and gene expression were quantified. IGF2 increased both estradiol and progesterone production by granulosa cells, and cells from large follicles were more responsive to the effects of IGF2 than those from small follicles. Abundance of aromatase (CYP19A1) mRNA was stimulated by IGF2 and IGF1. The effective dose (ED 50 ) of IGF2 stimulating 50% of the maximal estradiol production was 63 ng/ml for small follicles and 12 ng/ ml for large follicles, and these values were not affected by FSH. The ED 50 of IGF2 for progesterone production was 20 ng/ml for both small and large follicles. IGF2 also increased proliferation of granulosa cells by 2-to 3-fold, as determined by increased cell numbers and 3 H-thymidine incorporation into DNA. Treatment with IGF1R antibodies reduced the stimulatory effect of IGF2 and IGF1 on estradiol production and cell proliferation. Specific receptors for 125 I-IGF2 existed in granulosa cells, and 2-day treatment with estradiol, FSH, or cortisol had no significant effect on specific 125 I-IGF2 binding. Also, FSH treatment of small-and large-follicle granulosa cells had no effect on IGF2R mRNA levels, whereas IGF1 decreased IGF2R mRNA and specific 125

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Binding of Urokinase-type Plasminogen Activator Receptor (uPAR) to the Mannose 6-Phosphate/Insulin-like Growth Factor II Receptor

Cited by 32 publications

References 49 publications

PTOV1 Enables the Nuclear Translocation and Mitogenic Activity of Flotillin-1, a Major Protein of Lipid Rafts

PTOV1 Enables the Nuclear Translocation and Mitogenic Activity of Flotillin-1, a Major Protein of Lipid Rafts

Proteomics Analysis of Serum from Mutant Mice Reveals Lysosomal Proteins Selectively Transported by Each of the Two Mannose 6-Phosphate Receptors

Insulin-Like Growth Factor (IGF) 2 Stimulates Steroidogenesis and Mitosis of Bovine Granulosa Cells Through the IGF1 Receptor: Role of Follicle-Stimulating Hormone and IGF2 Receptor1

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