Complete primary structure and genomic organization of the mouse Col14a1 gene

In Silico Analysis of Collagens Missense SNPs and Human Abnormalities

Collagens are the most abundant proteins in the extra cellular matrix/ECM of human tissues that are encoded by different genes. There are single nucleotide polymorphisms/SNPs which are considered as the most useful biomarkers for some disease diagnosis or prognosis. The aim of this study is screening and identifying the functional missense SNPs of human ECM-collagens and investigating their correlation with human abnormalities. All of the missense SNPs were retrieved from the NCBI SNP database and screened for a global frequency of more than 0.1. Seventy missense SNPs that met the screening criteria were characterized for functional and stability impact using six and three protein analysis tools, respectively. Next, HOPE and geneMANIA analysis tools were used to show the effect of SNPs on three-dimensional structure (3D) and physical interaction of proteins. Results showed that 13 missense SNPs (rs2070739, rs28381984, rs13424243, rs1800517, rs73868680, rs12488457, rs1353613, rs59021909, rs9830253, rs2228547, rs3753841, rs2855430, and rs970547), which are in nine different collagen genes, affect the structure and function of different collagen proteins. Among these polymorphisms, COL4A3-rs13424243 and COL6A6-rs59021909 were predicted as the most effective ones. On the other hand, designed mutated and native 3D of rs13424243 variant illustrated that it can disturb the protein motifs. Also, geneMANIA predicted that COL4A3 and COL6A6 are interacting with some proteins including: DDR1, COL6A1, COL11A2 and so on. Based on our findings, ECM-collagens functional SNPs are important and may be considered as a risk factor or molecular marker for human disorders in the future studies.

Tumorigenic Interplay Between Macrophages and Collagenous Matrix in the Tumor Microenvironment

The tumor microenvironment is a heterogeneous tissue that in addition to tumor cells, contain tumor-associated cell types such as immune cells, fibroblasts, and endothelial cells. Considerably important in the tumor microenvironment is its noncellular component, namely, the extracellular matrix (ECM). In particular, the collagenous matrix is subjected to significant alterations in its composition and structure that create a permissive environment for tumor growth, invasion, and dissemination. Among tumor-infiltrating immune cells, tumor-associated macrophages (TAMs) are numerous in the tumor stroma and are locally educated to mediate important biological functions that profoundly affect tumor initiation, growth, and dissemination. While the influence of TAMs and mechanical properties of the collagenous matrix on tumor invasion and progression have been comprehensively investigated individually, their interaction within the complex tumor microenvironment was overlooked. This review summarizes accumulating evidence that indicate the existence of an intricate tumorigenic crosstalk between TAMs and collagenous matrix. A better mechanistic comprehension of this reciprocal interplay may open a novel arena for cancer therapeutics.

Tumor macrophages are pivotal constructors of tumor collagenous matrix

Tumor-associated macrophages are pivotal constructors of the tumoral ECM structure and molecular composition. In particular, they orchestrate the buildup of the tumorigenic collagenous ECM niche.

Tumor-associated macrophages (TAMs) promote tumor development, invasion, and dissemination by various mechanisms. In this study, using an orthotopic colorectal cancer (CRC) model, we found that monocyte-derived TAMs advance tumor development by the remodeling of its extracellular matrix (ECM) composition and structure. Unbiased transcriptomic and proteomic analyses of (a) TAM-abundant and -deficient tumor tissues and (b) sorted tumor-associated and -resident colonic macrophage subpopulations defined a distinct TAM-induced ECM molecular signature composed of an ensemble of matricellular proteins and remodeling enzymes they provide to the tumor microenvironment. Remarkably, many of these ECM proteins are specifically increased in human CRC versus healthy colon. Specifically, we demonstrate that although differentiating into TAMs, monocytes up-regulate matrix-remodeling programs associated with the synthesis and assembly of collagenous ECM, specifically collagen types I, VI, and XIV. This finding was further established by advanced imaging showing that TAMs instruct the deposition, cross-linking, and linearization of collagen fibers during tumor development, especially at areas of tumor invasiveness. Finally, we show that cancer-associated fibroblasts are significantly outnumbered by TAMs in this model and that their expression of collagen XIV and I is reduced by TAM deficiency. Here, we outline a novel TAM protumoral function associated with building of the collagenous ECM niche.

Collagens and proteoglycans of the cornea: importance in transparency and visual disorders

The cornea represents the external part of the eye and consists of an epithelium, a stroma and an endothelium. Due to its curvature and transparency this structure makes up approximately 70% of the total refractive power of the eye. This function is partly made possible by the particular organization of the collagen extracellular matrix contained in the corneal stroma that allows a constant refractive power. The maintenance of such an organization involves other molecules such as type V collagen, FACITs (fibril-associated collagens with interrupted triple helices) and SLRPs (small leucine-rich proteoglycans). These components play crucial roles in the preservation of the correct organization and function of the cornea since their absence or modification leads to abnormalities such as corneal opacities. Thus, the aim of this review is to describe the different corneal collagens and proteoglycans by highlighting their importance in corneal transparency as well as their implication in corneal visual disorders.

The cysteine-rich domain of snake venom metalloproteinases is a ligand for von Willebrand factor A domains: role in substrate targeting

Snake venom metalloproteinases (SVMPs) are members of the Reprolysin family of metalloproteinases to which the ADAM (a disintegrin and metalloproteinase) proteins also belong. The disintegrin-like/cysteine-rich domains of the ADAMs have been implicated in their function. In the case of the SVMPs, we hypothesized that these domains could function to target the metalloproteinases to key extracellular matrix proteins or cell surface proteins. Initially we detected interaction of collagen XIV, a fibril-associated collagen with interrupted triple helices containing von Willebrand factor A (VWA) domains, with the PIII SVMP catrocollastatin. Next we investigated whether other VWA domain-containing matrix proteins could support the binding of PIII SVMPs. Using surface plasmon resonance, the PIII SVMP jararhagin and a recombinant cysteine-rich domain from a PIII SVMP were demonstrated to bind to collagen XIV, collagen XII, and matrilins 1, 3, and 4. Jararhagin was shown to cleave these proteins predominantly at sites localized at or near the VWA domains suggesting that it is the VWA domains to which the PIII SVMPs are binding via their cysteine-rich domain. In light of the fact that these extracellular matrix proteins function to stabilize matrix, targeting the SVMPs to these proteins followed by their specific cleavage could promote the destabilization of extracellular matrix and cell-matrix interactions and in the case of capillaries could contribute to their disruption and hemorrhage. Although there is only limited structural homology shared by the cysteine-rich domains of the PIII SVMPs and the ADAMs our results suggest an analogous function for the cysteine-rich domains in certain members of the expanded ADAM family of proteins to target them to VWA domain-containing proteins.

TGF-beta1 generates a specific multicomponent extracellular matrix in human coronary SMC

BACKGROUND

Transforming growth factor (TGF-beta(1)) is postulated to play an important role in maintaining the structure and function of arterial tissue and protection against development of arteriosclerosis. The TGF-beta(1)-induced production of a stable extra-cellular matrix-rich plaque phenotype is suggested to be part of the protection against a switch to an unstable rupture-prone arteriosclerotic plaque.

MATERIALS AND METHODS

This study addresses the question of whether the expression profile and the type of extra-cellular matrix (ECM) generated by TGF-beta(1) stimulation have the structural feature of a fibril-rich stable matrix. Seventeen genes codings for ECM components of human coronary smooth muscle cells (SMCs) after a 24-h stimulation by TGF-beta(1) have been analyzed.

RESULTS

Real-time RT-PCR was used to quantify the mRNA of genes under investigation. It was found that after TGF-beta(1) stimulation (a) the up-regulation of COL1A1-specific mRNA was associated with increased [(3)H]proline incorporation into the alpha-1 and -2 chains of collagen type I, (b) the up-regulation of biglycan- and syndecan-1-specific mRNA corresponded to an increased [(35)S]sulphate and [4,5-(3)H]leucine incorporation into the biglycan molecule and to an increase of syndecan-1 protein, (c) the up-regulated FGF-2 gene accounted predominantly for the ECM-bound subfraction of FGF-2-protein and (d) fibronectin and thrombospondin exhibited a significantly higher mRNA level. In contrast collagen XIV, a minor collagen type, and the proteoglycan decorin were down-regulated. The down-regulated decorin changed its structure by elongation and reduced GlcA to IdoA epimerization of the dermatan sulphate side-chain as judged by [(35)S]sulphate metabolic labelling experiments. No significant changes in response to TGF-beta(1) were observed for the collagen types III, VI and XVI, for versican, perlecan and the syndecans-2 and -4.

CONCLUSIONS

It was concluded from the data that the TGF-beta(1)-induced formation of a highly specific multicomponent extra-cellular matrix on coronary arterial SMCs could provide in vivo mechanical strength to the neointima in arteriosclerotic lesions and to the fibrous cap overlying the lipid core.

Collagen types XII and XIV are present in basement membrane zones during human embryonic development

The collagens constitute a large group of proteins in the extracellular matrix that can be divided into several distinct families. Collagen types XII and XIV belong to a subgroup of non-fibrillar-collagens termed (fibril-associated collagens with interrupted triple-helices) (FACIT) and may be involved in basement membrane regulation providing specific molecular bridges between fibrils and other matrix components. However, the tissue distribution of the two proteins during human embryogenesis is still unclear. As a first step toward the elucidation of their possible cell biological functions, we compared the distribution of the two collagens during human organogenesis at the light microscopical level. We detected specific differences between the expression patterns of the two molecules, which may be related to their respective function within the basement membrane zones during human embryonic development. For example, in the developing intestine, collagen type-XII was present in the basement membrane zones of epithelia and endothelia. However, collagen type-XIV was restricted to the mesothelial basement membrane zones. We conclude that both collagens might well be able to serve different functions during human embryonic development although their structures are highly similar.

Developmental changes in the fetal pig transcriptome

Growth and development of pig fetuses is dependent on the coordinated expression of multiple genes. Between 21 and 45 days of gestation, fetuses experience increasing growth rates that can result in uterine crowding and increased mortality. We used differential display reverse transcription-PCR (DDRT-PCR) to identify differentially expressed genes in pig fetuses at 21, 35, and 45 days of gestation. Pig cDNAs were identified with homologies to CD3 gamma-subunit, collagen type XIV alpha1, complement component C6, craniofacial developmental protein 1, crystallin-gammaE, DNA binding protein B, epsilon-globin, formin binding protein 2, ribosomal protein L23, small acidic protein, secreted frizzled related protein 2, titin, vitamin D binding protein, and two hypothetical protein products. Two novel expressed sequence tags (ESTs) were also identified. Expression patterns were confirmed for eight genes, and spatiotemporal expression of three genes was evaluated. We identified novel transcriptome changes in fetal pigs during a period of rapid growth. These changes involved genes with a spectrum of proposed functions, including musculoskeletal growth, immune system function, and cellular regulation. This information can ultimately be used to enhance production efficiency through improved pig growth and survival.