Members Of Collagen Family Research Articles

Pressure Overload Creates Right Ventricular Diastolic Dysfunction in a Mouse Model: Assessment by Echocardiography

Noninvasive diagnostic tools for right ventricular (RV) dysfunction measurements are increasingly being used, although their association with the pathologic mechanisms of dysfunction is poorly understood. Although investigations have focused mainly on RV systolic function, RV diastolic function remains mostly neglected. The aim of this study was to test which echocardiographic parameters best reflect RV diastolic function in mice. Pulmonary artery banding (PAB) was used to induce RV pressure overload in mice. Transthoracic echocardiography and invasive hemodynamic measurements were performed after 3 weeks in PAB and sham-operated mice. Subsequently, the hearts were investigated by histology and analyzed for gene expression. PAB-induced pressure overload (RV systolic pressure PAB 52.6 ± 11.8 mm Hg vs sham 27.0 ± 2.7 mm Hg) resulted in RV hypertrophy and remodeling, as reflected by increased Fulton index (PAB 0.37 ± 0.05 vs sham 0.25 ± 0.02, P = .001). Masson's trichrome staining revealed increased interstitial fibrosis (PAB 12.25 ± 3.12% vs sham 3.97 ± 1.58%, P = .002). This was associated with significant systolic RV dysfunction as demonstrated by reduced contractility index and diastolic dysfunction as demonstrated by end-diastolic pressure (PAB 2.66 ± 0.83 mm Hg vs sham 1.49 ± 0.50 mm Hg, P < .001) and τ (PAB 40.0 ± 16.1 msec vs sham 13.0 ± 3.5 msec, P < .001). Messenger ribonucleic acid expression of β-myosin heavy chain, atrial and brain natriuretic peptides, collagen family members was elevated, and the sarco/endoplasmic reticulum Ca(2+)-ATPase was decreased. Echocardiography revealed significant increases in RV free wall thickness and isovolumic relaxation time and a decrease in left ventricular eccentricity index, E', and tricuspid annular plane systolic excursion. Isovolumic relaxation time and E' were significantly correlated with end-diastolic pressure (rs = 0.511 and -0.451) and τ (rs = 0.739 and -0.445, respectively). Moreover, E' was negatively correlated with the degree of RV fibrosis (rs = -0.717). Within 3 weeks, PAB causes pressure overload-induced RV hypertrophy and remodeling with compensated systolic and diastolic dysfunction in mice. RV free wall thickness, tricuspid annular plane systolic excursion, E', E/E' ratio, and isovolumic relaxation time appear to be the most reliable echocardiographic parameters for the assessment of RV dysfunction.

SLY1 and Syntaxin 18 specify a distinct pathway for procollagen VII export from the endoplasmic reticulum.

TANGO1 binds and exports Procollagen VII from the endoplasmic reticulum (ER). In this study, we report a connection between the cytoplasmic domain of TANGO1 and SLY1, a protein that is required for membrane fusion. Knockdown of SLY1 by siRNA arrested Procollagen VII in the ER without affecting the recruitment of COPII components, general protein secretion, and retrograde transport of the KDEL-containing protein BIP, and ERGIC53. SLY1 is known to interact with the ER-specific SNARE proteins Syntaxin 17 and 18, however only Syntaxin 18 was required for Procollagen VII export. Neither SLY1 nor Syntaxin 18 was required for the export of the equally bulky Procollagen I from the ER. Altogether, these findings reveal the sorting of bulky collagen family members by TANGO1 at the ER and highlight the existence of different export pathways for secretory cargoes one of which is mediated by the specific SNARE complex containing SLY1 and Syntaxin 18.DOI: http://dx.doi.org/10.7554/eLife.02784.001.

Computational analysis of bovine alpha-1 collagen sequences.

Bovine collagen alpha-1 is a naturally occurring extracellular matrix protein found in tendons and other connective tissues. It plays a vital role in cell growth, differentiation, attachment, and migration. Recent findings have established that collagen alpha-1 is involved in osteogenesis imperfecta phenotype in cattle but deep information about other members of this large family is not available so far. So with a view to finding a new edge and attempt to figure out a correlation among the well attributed Bovine alpha-1 collagen sequences are executed and analyzed. To do so, comparative analysis among the 28 members of collagen family has been carried out using Computational tools. Consequently, based on the physico-chemical, secondary structural, functional and phylogenetic classifications, we have selected collagen 12, 14 and 20 as targets for pathological conditions. These proteins belong to the FACIT family and significantly showed low glycine and proline content, high instability and aliphatic index. Moreover, FACIT family collagens contain multiple triple helical domains and being members of the FACIT family, bovine collagen 12, 14, 20 do not form fibrils by themselves but they are associated to collagen 1 associated fibrils. These collagen molecules might be crucial candidates to detect and understand the process of matrix remodeling in diseases especially in the arena of cellular compartments.

The collagen family members as cell adhesion proteins

The collagen family of extracellular matrix proteins has played a fundamental role in the evolution of multicellular animals. At the present, 28 triple helical proteins have been named as collagens and they can be divided into several subgroups based on their structural and functional properties. In tissues, the cells are anchored to collagenous structures. Often the interaction is indirect and mediated by matrix glycoproteins, but cells also express receptors, which have the ability to directly bind to the triple helical domains in collagens. Some receptors bind to sites that are abundant in all collagens. However, increasing evidence indicates that the coevolution of collagens and cell adhesion mechanisms has given rise to receptors that bind to specific motifs in collagens. These receptors may also recognize the different members of the large collagen family in a selective manner. This review summarizes the present knowledge about the properties of collagen subtypes as cell adhesion proteins.

Complete primary structure and genomic organization of the mouse Col14a1 gene.

The entire mouse cDNA sequence for type XIV collagen was determined using overlapping PCR products. The 6456 nucleotide (nt) cDNA sequence contains a 5391-nt open reading frame encoding 1797 amino acid residues. The amino terminus has a 28-residue signal peptide that is followed by the mature polypeptide of 1769 amino acid residues with a calculated molecular mass of 193.2 kDa. The mouse alpha1(XIV) collagen chain is predicted to contain all the structural domains described for the polypeptide in chicken and human. These include fibronectin type III repeats, von Willebrand factor A domains, thrombospondin-N-terminal-like domains and two triple-helical domains similar to those of other collagen family members. The amino acid residue sequence of human alpha1(XIV) collagen showed an overall identity of 74% to the chicken sequence and 88% to the human sequence. The entire mouse genomic structure has been determined and is made up of 48 exons. Alternatively spliced forms of mouse type XIV, collagen were not identified corresponding to the findings for the human form.

Cholesterol and Cholate Components of an Atherogenic Diet Induce Distinct Stages of Hepatic Inflammatory Gene Expression

Atherosclerosis in inbred mouse strains has been widely studied by using an atherogenic (Ath) diet containing cholesterol, cholic acid, and fat, but the effect of these components on gene expression has not been systematically examined. We employed DNA microarrays to interrogate gene expression levels in liver of C57BL/6J mice fed the following five diets: mouse chow, the Ath diet, or modified versions of the Ath diet in which either cholesterol, cholate, or fat were omitted. Dietary cholesterol and cholate produced discrete gene expression patterns. Cholesterol was required for induction of genes involved in acute inflammation, including three genes of the serum amyloid A family, three major histocompatibility class II antigen genes, and various cytokine-related genes. In contrast, cholate induced expression of genes involved in extracellular matrix deposition in hepatic fibrosis, including five collagen family members, collagen-interacting proteins, and connective tissue growth factor. The gene expression findings were confirmed by biochemical measurements showing that cholesterol was required for elevation of circulating serum amyloid A, and cholate was required for accumulation of collagen in the liver. The possibility that these gene expression changes are relevant to atherogenesis in C57BL/6J mice was supported by the observation that the closely related, yet atherosclerosis-resistant, C57BL/6ByJ strain was largely resistant to dietary induction of the inflammatory and fibrotic response genes. These results establish that cholesterol and cholate components of the Ath diet have distinct proatherogenic effects on gene expression and suggest a strategy to study the contribution of acute inflammatory response and fibrogenesis independently through dietary manipulation.

Complete Primary Structure of Two Splice Variants of Collagen XII, and Assignment of α1(XII) Collagen (COL12A1), α1(IX) Collagen (COL9A1), and α1(XIX) Collagen (COL19A1) to Human Chromosome 6q12–q13

Overlapping cDNA clones that encode the full-length human α1(XII) collagen polypeptides were isolated. The long variant molecule cDNA of 9750 nucleotides (nt) contains a 9189-nt open reading frame encoding 3063 amino acid residues. The short variant molecule cDNA of 6258 nt contains a 5697-nt open reading frame encoding 1899 amino acid residues. At the amino terminus of each variant is a 24-residue signal peptide that is followed by the mature polypeptides of 3039 amino acid residues with a calculated molecular mass of 330,759 Da for the long variant and 1875 amino acid residues with a calculated molecular mass of 203,163 Da for the short variant polypeptide. The human collagen XII chains are predicted to have all the structural domains described for the molecules in chicken and mouse, including, fibronectin type III repeats, von Willebrand factor A domains, and two triple-helical domains similar to those of all the other collagen family members. The amino acid residue sequence of human α1(XII) collagen showed 92% identity to the mouse chain and 78% identity to the chicken chain. The sequence of three peptide fragments of collagen XII isolated from human placenta was identical to the sequence predicted from the deduced cDNA sequence and confirms that the cDNA encodes human α1(XII) collagen. An isolated genomic clone was used to map the locus of the COL12A1 gene to chromosome 6q12–q13, very close to the locus of the FACIT collagen genes COL9A1 and COL19A1. RT-PCR on a variety of cDNAs demonstrates that both variant transcripts appear in human amnion, chorion, skeletal muscle, small intestine, and in cell cultures of human dermal fibroblasts, keratinocytes, and endothelial cells. Only the small variant transcript is apparent in human lung, placenta, kidney, and a squamous cell carcinoma cell line. These results confirm the previous observations showing that collagen XII is found in collagen I-containing tissues.

The phorbol ester TPA regulates collagen gene expression at the transcriptional level.

Previously, we reported that growth activation of quiescent 3T3-L1 cells by TPA led to a rapid increase of pro-alpha 2 (I) collagen mRNA and protein, while induction of pro-alpha 2 (I) was not observed in VT-1 cells, a line non-mitogenic in the presence of TPA (26). Here, we further examine the expression of pro-alpha 2 (I) collagen during mitogenic stimulation at the molecular level. In addition to pro-alpha 2 (I) mRNA, TPA treatment increased mRNA production of other collagen family members, pro-alpha 1 (I) and pro-alpha 1 (III) although in reduced amounts relative to pro-alpha 2 (I). In contrast to pro-alpha 2 (I), the mRNA expression profiles of several protooncogenes were regulated in both VT-1 and 3T3-L1 cells. Consistent with increased mRNA levels, TPA treated 3T3-L1 cells produced a matrix abundant in collagen type I protein. In vitro nuclear "run-on" transcription assays demonstrated a 4-fold increase in pro-alpha 2 (I) mRNA that was maximal within 10 min of TPA treatment. Using a chloramphenicol-acetyl transferase (CAT) assay, we identified a TPA sensitive domain within the promoter of the COL1A2 gene. These results establish COL1A2 as an early growth responsive gene, and that its regulation is PKC dependent. Additionally, the increased expression of protooncogenes and transin during TPA stimulation of non-mitogenic VT-1 cells indicated that the regulation of these genes is independent of PKC, indicating the existence of multiple regulatory mechanisms amongst early response genes.