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Cell surface proteoglycans syndecan-1 and -4 bind overlapping but distinct sites in laminin ?3 LG45 protein domain.

ABSTRACT: Keratinocyte migration during epidermal repair depends on interactions between cellular heparan sulfate proteoglycan receptors, syndecan-1 and -4, and the C-terminal globular domains (LG45) of the extracellular matrix protein laminin 332. This study investigates the molecular basis of the binding specificity of the syndecan-1 and -4 receptors expressed by human keratinocytes. We used site-directed mutagenesis to alter a recombinant LG45 protein by substituting the most critical basic residues with glutamine. All proteins were expressed in mammalian cells, purified, and characterized biochemically. We used in vitro binding assays, including surface plasmon resonance, to examine interactions between mutated LG45 and heparan sulfates, syndecan-1 and -4. We identify a major heparin binding domain on the outer edge of a ?-strand of LG45 surrounded by a track of converging low affinity residues. This domain harbors distinctive syndecan-1 and -4 binding-specific sequences. This is the first study to demonstrate a binding specificity of two proteoglycans produced by a single cell type. In addition, we found that although syndecan-1 interacts exclusively through its glycosaminoglycan chains, syndecan-4 binding relies on both its core protein and its heparan sulfate chains. These results suggest that LG45 may trigger different signals toward keratinocytes depending on its interaction with syndecan-1 or -4.

SUBMITTER: Carulli S

PROVIDER: S-EPMC3320972 | biostudies-literature | 2012 Apr

REPOSITORIES: biostudies-literature

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Cell surface proteoglycans syndecan-1 and -4 bind overlapping but distinct sites in laminin α3 LG45 protein domain.

Carulli Sonia S Beck Konrad K Dayan Guila G Boulesteix Sophie S Lortat-Jacob Hugues H Rousselle Patricia P

The Journal of biological chemistry 20120220 15

Keratinocyte migration during epidermal repair depends on interactions between cellular heparan sulfate proteoglycan receptors, syndecan-1 and -4, and the C-terminal globular domains (LG45) of the extracellular matrix protein laminin 332. This study investigates the molecular basis of the binding specificity of the syndecan-1 and -4 receptors expressed by human keratinocytes. We used site-directed mutagenesis to alter a recombinant LG45 protein by substituting the most critical basic residues wi ...[more]

PMID: 22351752

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Project description:In the effort to identify novel, relevant prognostic factors for the clinical monitoring of patients affected by squamous cell carcinomas of the oral cavity (SCCOC) we have pursued a molecular screening at the gene and protein level on 166 surgical specimens derived from patients with an accessible clinical history and >2 years follow-up. The screening was focalized on cell surface proteoglycans (PGs) based upon the assumption that altered expression of individual or groups of PGs may predict disease course and therapeutic response, and thereby allow for a clusterization of patients in discrete subsets. The 11 PGs contemplated in the screening and including syndecan-1-4 (SDC1-SDC4), glypican-1-6 (GPC1-GPC6) and NG2, were found to be transcribed at variable levels and with a decreasing frequencies SDC1>SDC4>SDC2>SDC3>GPC4>GPC3>GPC1 >GPC5>CSPG4>GPC6>GPC2. SCCOC cells de novo transcribed GPC2, GPC5 and NG2 and regulated all SDCs, GPC1, -3, -4 and -6, suggesting that an altered surface profile of PG is a characterizing trait of these tumor cells In situ distributional analysis of these PGs on a total of 149 cases revealed many fewer lesions actually translated the molecules which were detected with a frequency range of 14% (SDC2) to 92% (SDC1). Noteworthy was, however, that SDC2 was present in the intra-lesional stroma and in association with neovessels in all the cases, suggesting that this specific PG was a key element of stromal fibroblasts and angiogenic structures. Poor translational efficacy of several of the PGs was accompanied by an apparent retention of the molecules within the cytoplasm of SCCOC cells. This finding suggest that modulated expression of cell surface PGs may be a representative secondary event in SCCOC and that these carcinoma cells do not mount up an effective intracellular machinery for proper shuttling and membrane incorporation of the PGs. A total of 166 surgical specimens of primary SCCOC were collected after informed consent from individuals who underwent surgical removal of the tumor lesions and RNA from 119 surgical specimens were extracted; a pool of RNAs extracted from 5 normal epithelia tissues was adopted as a sample calibrator (HEALTHY sample). cDNA from each samples and from pool of normal epithelial were loaded on TLDA and amplified. HEALTHY sample were amplified 20 times in two replicates (in each TLDA card); each patient sample were amplified 1 time in two replicates and 7 samples of them were loaded two times in a separate TLDA card (for a total of 4 replicates).

Dataset Information

Cell surface proteoglycans syndecan-1 and -4 bind overlapping but distinct sites in laminin ?3 LG45 protein domain.

Publications

Cell surface proteoglycans syndecan-1 and -4 bind overlapping but distinct sites in laminin α3 LG45 protein domain.

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