Partial covalent structure of the human alpha 2 type V collagen chain

Genomic organization of the human COL3A1 and COL5A2 genes: COL5A2 has evolved differently than the other minor fibrillar collagen genes

We report here on the complete structure of the human COL3A1 and COL5A2 genes. Collagens III and V, together with collagens I, II and XI make up the group of fibrillar collagens, all of which share a similar structure and function; however, despite the similar size of the major triple-helical domain, the number of exons coding for the domain differs between the genes for the major fibrillar collagens characterized so far (I, II, and III) and the minor ones (V and XI). The main triple-helical domain being encoded by 49-50 exons, including the junction exons, in the COL5A1, COL11A1 and COL11A2 genes, but by 43-44 exons in the genes for the major fibrillar collagens. Characterization of the genomic structure of the COL3A1 gene confirmed its association with the major fibrillar collagen genes, but surprisingly, the genomic organization of the COL5A2 gene was found to be similar to that of the COL3A1 gene. We also confirmed that the two genes are located in tail-to-tail orientation with an intergenic distance of approximately 22 kb. Phylogenetic analysis suggested that they have evolved from a common ancestor gene. Analysis of the genomic sequences identified a novel single nucleotide polymorphism and a novel dinucleotide repeat. These polymorphisms should be useful for linkage analysis of the Ehlers-Danlos syndrome and related disorders.

Complete primary structure of the chicken alpha1(V) collagen chain

Chicken alpha1(V) collagen cDNAs have been cloned by a variety of methods and positively identified. We present here the entire translated sequence of the chick polypeptide and compare selected regions to other collagen chains in the type V/XI family.

Basement-membrane stromal relationships: interactions between collagen fibrils and the lamina densa

Collagens, the most abundant molecules in the extracellular space, predominantly form either fibrillar or sheet-like structures-the two major supramolecular conformations that maintain tissue integrity. In connective tissues, other than cartilage, collagen fibrils are mainly composed of collagens I, III, and V at different molecular ratios, exhibiting a D-periodic banding pattern, with diameters ranging from 30 to 150 nm, that can form a coarse network in the extracellular matrix in comparison with a fine meshwork of lamina densa. The lamina densa represents a stable sheet-like meshwork composed of collagen IV, laminin, nidogen, and perlecan compartmentalizing tissue from one another. We hypothesize that the interactions between collagen fibrils and the lamina densa are crucial for maintaining tissue-tissue interactions. A detailed analysis of these interactions forms the basis of this review article. Here, we demonstrate that there is a direct connection between collagen fibrils and the lamina densa and propose that collagen V may play a crucial role in this connection. Collagen V might also be involved in regulation of collagen fibril diameter and anchoring of epithelia to underlying connective tissues.

Expression of collagens I, III, IV and V mRNA in excimer wounded rat cornea: analysis by semi-quantitative PCR

A semi-quantitative polymerase chain reaction (PCR) methodology was used to evaluate the kinetic changes occurring in collagens I, III, IV and V mRNA in rat cornea following excimer laser keratectomy. cDNA was synthesized from RNA extracted from rat cornea at various times following excimer laser photoablative keratectomy. Collagen cDNA sequences were subsequently amplified using specific sets of oligonucleotide primers. Competitive PCR amplification was carried out using an internal standard so that a semi-quantitative analysis of message for synthesis of collagen types I, III, IV and V could be performed and time course dynamics of message for these collagens studied. There was a biphasic increase in the levels of collagens III, IV and V mRNA following excimer laser keratectomy. Collagen I mRNA levels demonstrated a more sustained increase and were still elevated at 6 weeks following wounding. Collagens IV and V mRNA showed the largest increase with an approximate three fold increase over controls between 4 days and 1 week. Our results demonstrate that upregulation of stromal collagens I, III, and V mRNA and basement membrane collagen IV mRNA occurs in rat cornea following excimer laser keratectomy.

The human COL11A2 gene structure indicates that the gene has not evolved with the genes for the major fibrillar collagens

The human COL11A2 gene was analyzed from two overlapping cosmid clones that were previously isolated in the course of searching the human major histocompatibility region (Janatipour, M., Naumov, Y., Ando, A., Sugimura, K., Okamoto, N., Tsuji, K., Abe, K., and Inoko, H. (1992) Immunogenetics 35, 272-278). Nucleotide sequencing defined over 28,000 base pairs of the gene. It was shown to contain 66 exons. As with most genes for fibrillar collagens, the first intron was among the largest, and the introns at the 5'-end of the gene were in general larger than the introns at the 3'-end. Analysis of the exons coding for the major triple helical domain indicated that the gene structure had not evolved with the genes for the major fibrillar collagens in that there were marked differences in the number of exons, the exon sizes, and codon usage. The gene was located close to the gene for the retinoic X receptor beta in a head-to-tail arrangement similar to that previously seen with the two mouse genes (P. Vandenberg and D. J. Prockop, submitted for publication). Also, there was marked interspecies homology in the intergenic sequences. The amino acid sequences and the pattern of charged amino acids in the major triple helix of the alpha 2(XI) chain suggested that the chain can be incorporated into the same molecule as alpha 1(XI) and alpha 1(V) chains but not into the same molecule as the alpha 3(XI)/alpha 1(II) chain. The structure of the carboxyl-terminal propeptide was similar to the carboxyl-terminal propeptides of the pro alpha 1(XI) chain and pro alpha chains of other fibrillar collagens, but it was shorter because of internal deletions of about 30 amino acids.

Another look at collagen V and XI molecules

The fibrillar collagens are the most abundant proteins of extracellular matrices. Among them, collagens V and XI are quantitatively minor components which participate in the formation of the fibrillar collagen network. Since these collagens were discovered, studies have demonstrated that they may play a fundamental role in the control of fibrillogenesis, probably by forming a core within the fibrils. Another characteristic of these collagens is the partial retention of their N-propeptide extensions in tissue forms, an unusual observation in comparison to the other known fibrillar collagens. The tissue locations of collagens V and XI are different, but their structural and biological properties seem to be closely related. It has been shown that their primary structures are highly conserved at both the gene and protein levels, and that these conserved features are the bases of their similar biological properties. In particular, they are both resistant to mammalian collagenases, and surprisingly sensitive to trypsin treatment. Collagens V and XI are usually buried within the major collagen fibrils, although they have both cell adhesion and heparin binding sites which could be of crucial importance in physiological processes such as development and wound healing. It has became evident that several molecules are in fact heterotypic associations of chains from both collagens V and XI, demonstrating that these two collagens are not distinct types but a single type which can be called collagen V/XI.

The human rhabdomyosarcoma cell line A204 lays down a highly insoluble matrix composed mainly of alpha 1 type-XI and alpha 2 type-V collagen chains

The biosynthesis of collagen by the A204 cell line was examined using polyclonal antibodies raised against collagen type V and type XI. The study of the pepsin-digested collagen showed that it is composed mainly of alpha 1(XI) and alpha 2(V) collagen chains in an apparent 2:1 ratio, suggesting the formation of heterotypic molecules [alpha 1(XI)]2 alpha 2(V). The existence of this chain stoichiometry was further demonstrated by immunoprecipitation of the molecule with an antibody recognizing alpha 2(V) but not alpha 1(XI) collagen chains. Electron microscopy analyses of 24-h cultures showed that this matrix is composed of thin fibrils, that can be decorated with immunogold-labelled anti-(type-V collagen) IgG, but not with anti-(type-XI collagen) IgG. The collagen matrix laid down by A204 cells is highly insoluble. In the presence of beta-aminopropionitrile, an inhibitor of lysyl oxidase, only a small proportion of intact collagen could be extracted without proteolytic treatment. Immunoblotting of intact medium collagen from cultures performed in the presence of beta-aminopropionitrile showed four distinct bands with each antibody. The migration of the bands, stained with anti-(type-V collagen) IgG, had apparent molecular masses of 127, 149, 161 and 198 kDa (compared to globular standards) while the bands stained with anti-(type-XI collagen) IgG had apparent masses of 145, 182, 207 and 225 kDa. These data indicate that type-V and type-XI collagen chains can assemble in heterotypic isoforms. In this system, the synthesized isoforms are able to aggregate into a highly cohesive matrix and they undergo a proteolytic processing closely similar to that of other fibrillar collagens.

Localization of type II, IX and V collagen in the inner ear

Types II and IX collagen are traditionally considered cartilage collagens; however, within the inner ear, types II and IX collagen have a more diverse distribution. In the adult gerbil, type II collagen is the major fibrillar component. In the otic capsule it is present surrounding the osteocytes embedded and branching in the periosteal layer, in the cartilaginous rests of the enchondral layer, and in the endosteal layer bordering the membranous labyrinth. In the regions of the sensory cells, type II collagen is found in the osseous spiral lamina, the connective tissue of the spiral limbus, the subepithelial tissue of the maculae in the vestibule and the cristae in the ampullae, and in the spiral ligament. It is present in the non-cartilaginous and acellular structures of the tectorial membrane over the cochlear hair cells and the vestibular membrane lining the semicircular canals. Type IX collagen, when present, in all cases co-localizes with type II collagen but is found in more limited regions. It is found only in the cartilaginous rests of the enchondral bone, the tectorial membrane and the vestibular membrane. Type V-like collagen, a connective tissue collagen, is found to have a complementary localization to types II and IX collagen within the interstitial bone of the otic capsule, the osseous spiral lamina and the tectorial membrane, but it is absent from the vestibular membrane. This report is the first documenting the co-localization of types II and IX collagen.(ABSTRACT TRUNCATED AT 250 WORDS)

Distribution of collagens type V and VI in the normal human alveolar mucosa: an immunoelectronmicroscopic study using ultrathin frozen sections

The ultrastructural localization of collagens type V and VI in normal human gingival mucosa was investigated by immunoelectron microscopy. Twenty biopsies were fixed in dimethylsuberimidate and shock-frozen in slush nitrogen. Collagen type V was mainly located to meshworks of uniform nonstriated microfibrils of 12 to 20 nm width, which preferentially appeared in larger spaces between cross-striated major collagen fibrils. Occasionally single microfibrils of collagen type V fanned out from the ends of major collagen fibrils, which may indicate a role as a core fibril. Collagen type V was not found in the subepithelial basement membrane and the immediately adjacent stroma. Collagen type VI was detected in a loose reticular network of unbanded microfilaments that were morphologically distinguishable by knoblike protrusions every 100-110 nm. These microfilaments were found in the vicinity, but not as an intrinsic component, of the subepithelial basement membrane. Single filaments of collagen type VI filaments appeared to form bridges between neighboring cross-striated major collagen fibrils, suggesting an interconnecting role for this collagen type. The method presented appears to be excellently suited to study the normal and pathological supramolecular organization of the oral extracellular matrix.

Genes for collagen types I, IV, and V are transcribed in HeLa cells but a postinitiation block prevents the accumulation of type I mRNA

Collagen mRNA synthesis in HeLa cells was evaluated by in vitro transcription of type I collagen DNA, nuclear run-on studies, and steady-state mRNA analysis. Type I collagen mRNA was accurately initiated by HeLa cell RNA polymerase II in nuclear extracts, and run-on analysis indicted that mRNAs for collagen types alpha 1(I), alpha 2(I), alpha 1(III), alpha 1(IV), and alpha 2(V) were synthesized in HeLa cells. However, on assessing the steady-state levels of mRNAs of collagen types alpha 1(I), alpha 2(I), alpha 1(IV), and alpha 2(V), no type I mRNA was found in HeLa cells while types alpha 1(IV) and alpha 2(V) collagen mRNAs were observed. These results suggest that a postinitiation process prevents the accumulation of type I collagen mRNAs in HeLa cells. Persistence of types IV and V collagen mRNAs is consistent with the involvement of types IV and V collagen in adhesion of HeLa cells to glass or plastic.

Immunoelectron microscopical evidence that type V collagen is a fibrillar collagen: importance for an aggregating capability of the preparation for reconstituting banding fibrils

Type V collagen has already been shown, in many immunohistochemical studies, to be widely distributed in connective tissues. Its supramolecular structure, however, has been unclear. We demonstrate that the major aggregates formed from type V collagen solution in vitro are fine fibrils with a D-periodic banding pattern. Further, by using the immunogold labeling method, we find that these fibrils react strongly with anti-type V collagen antibody. Electronmicroscopic examination showed three kinds of aggregate: fine fibrils with periodic banding pattern, fine fibrils without banding pattern, and non-fibrillar materials. Both striated and nonstriated fibrils, when incubated with rat polyclonal anti-human type V collagen IgG followed by incubation with 15 nm-gold conjugated goat anti-rat IgG, were labeled with colloidal gold. We conclude that type V can be classified as a fibrillar collagen. Also, from the present findings together with previous studies, we believe type V collagen may exist in vivo in various connective tissues as fine fibrils with a 67 nm-periodic banding pattern, by itself, or with type I or type III fibrillar collagen, being located between, and connecting the basal lamina and interstitial collagen fibers.

Covalent structure of collagen: amino acid sequence of three cyanogen bromide-derived peptides from human alpha 1(V) collagen chain

Type V collagen was prepared from human amnionic/chorionic membranes and separated into alpha 1(V) and alpha 2(V) polypeptide chains. The alpha 1(V) chain was digested with cyanogen bromide and nine peptides were obtained and purified. Three of the peptides, alpha 1(V)CB1, CB4, and CB7 having molecular weights of 5000, 8000, and 6000, respectively, were further analyzed by amino acid sequence analysis and thermolytic or tryptic digestions. CB1 contained 54 amino acids and identification of its complete sequence was aided by thermolysin digestion and isolation of two peptides, Th1 and Th2. CB4 contained 81 amino acids and sequence analysis of intact CB4 and five tryptic peptides provided us with its complete amino acid sequence. The peptide CB7 contained 67 amino acids and was cleaved into four tryptic peptides that were used for complete sequence analysis. The above results represent the first available covalent structure information on the alpha 1(V) collagen chain. These data enabled us to establish the location of these peptides within the helical structure of other collagen chains. CB4 was homologous to residues 66-145 in the collagen chain while CB1 represented residues 146-200 and CB7 was homologous with residues 201-269. This alignment was facilitated by identification of a helical collagen crossing site consisting of Hyl-Gly-His-Arg located at positions 87-90 in all collagen chains of this size thus far identified. Seventy-one percent homology (excluding Gly residues) was found between amino acids in this region of the alpha 1(XI) and of alpha 1(V) collagen chains while only 21 and 19% identity was calculated for the same region of alpha 2(V) and alpha 1(I) collagen chains, respectively.

Collagens of normal and cirrhotic human liver

The collagens of normal and end-stage alcoholic cirrhotic human liver were investigated. Mild conditions of pepsin digestion were employed to preserved the more pepsin sensitive type IV collagen molecules while increasingly more harsh conditions were used which solubilized the type I and type III hepatic collagens. The total hepatic collagen content was elevated from 1.8-2.1 in normal liver to 7.3-8.2 percent in the end-stage alcoholic liver. The graded pepsin digestion resulted in solubilization of 76-90 percent of the total hepatic collagen. The genetically distinct types of collagen were fractionated into types I, III, IV and V preparations using judicious salt precipitation from dilute acid and neutral pH solutions. The average distribution of collagen was 42.5, 39.5, 6.9 and 10.6 percent types I, III, IV and V collagen respectively in normal liver compared to 56.6, 28.0, 5.5 and 9.6 percent respectively in the end-stage alcoholic livers. An additional 0.6 and 0.5 percent in normal and end-stage cirrhotic liver respectively were located in a fraction separating out of the salt concentration required for type VI collagen. The type IV collagen of basement membrane was separated into the constituent 95Kda alpha 1(IV) and alpha 2(IV) polypeptide chains by Agarose A 5m gel filtration with subsequent (carboxymethyl) CM-cellulose chromatography. These chains were indistinguishable from similar chains of type IV collagen isolated previously from human placenta. The type V collagen alpha chains, alpha 1(V) and alpha 2(V) were purified by a combination of Diethylaminoethyl (DEAE) and CM-cellulose chromatography. The individual chains were fragmented with cyanogen bromide to yield 9 peptides from the alpha 1(V) chain and 10 peptides from the alpha 2(V) collagen chain. These were purified and analyzed for amino acid content and molecular weight. The study suggests that all collagen types were elevated in the end-stage alcoholic liver, but type I collagen was disproportionately increased over all other collagens. These results are consistent with previous studies which demonstrated an elevated type I collagen in other fibrotic conditions such as lung fibrosis and hypertrophic scar. They do not, however, agree with the suggested disproportionate elevation of type V collagen in human alcoholic liver. The reasons for this discrepancy are discussed.

A nuclear factor 1 binding site mediates the transcriptional activation of a type I collagen promoter by transforming growth factor-beta

Transforming growth factor-beta (TGF-beta) increases the steady-state RNA levels of several fibroblast extracellular matrix proteins. Using DNA transfection, we show that TGF-beta stimulates the activity of the mouse alpha 2(l) collagen promoter 5- to 10-fold in mouse NIH 3T3 and rat osteosarcoma cells. Deletion analysis indicates that a segment of this promoter between -350 and -300, overlapping a nuclear factor 1 (NF1) binding site, is needed for TGF-beta stimulation. A 3 bp substitution mutation abolishing NF1 binding to this site inhibits TGF-beta activation. Insertion of this NF1 binding site 5' to the SV40 early promoter makes the promoter TGF-beta inducible, but the 3 bp substitution does not. Similarly, when the NF1 binding site at the replication origin of adenovirus 2 and 5 is inserted 5' to the SV40 promoter, the promoter responds to TGF-beta. Therefore an NF1 binding site mediates the transcriptional activation of the mouse alpha 2(l) collagen promoter by TGF-beta.

Collagen gene expression in keloids: analysis of collagen metabolism and type I, III, IV, and V procollagen mRNAs in keloid tissue and keloid fibroblast cultures

Regulation of collagen gene expression was studied in keloids and fibroblast cultures established from keloid biopsies from 9 patients. The collagen concentration in keloid tissue was not different from that in normal skin. The activities of 2 enzymes catalyzing intracellular collagen biosynthesis, prolyl 4-hydroxylase (PH) and galactosylhydroxylysyl glucosyltransferase (GGT) were significantly elevated in the keloids, the mean increase in the former enzyme being 5-fold and in the latter 3-fold with respect to the controls. The mean procollagen production rate in the keloid fibroblasts was at the control level, with only 1 keloid cell line showing a procollagen synthesis rate higher than the mean value + 2 SD of the controls. The mean PH and GGT activities of the keloid fibroblasts were not elevated, but PH activity in 2 cell lines and GGT activity in 1 cell line were higher than the mean + 2 SD for the controls. Cellular type I, III, IV, and V procollagen mRNAs were measured by slot blot hybridization using specific human cDNA clones for the various collagen types. The amounts of type I, III, and V procollagen mRNAs corresponded to the ratios in which these collagen types are produced by fibroblasts. No synthesis of type IV procollagen mRNA by keloid fibroblasts was observed. The total amount of type I and III procollagen mRNAs correlated significantly (p less than 0.01) with the procollagen synthesis rate measured after radioactive labeling of the cells in the keloid and control fibroblasts, indicating that collagen production in these cells is mainly controlled by regulating the final steady state levels of collagen mRNA. The results suggest that fibroblasts isolated from keloids often synthesize normal amounts of collagen.

Comparison of axial banding patterns in fibrils of type V collagen and type I collagen

Type V collagen and type I collagen were obtained from human placenta, essentially by salt fractionation. Precipitates were formed from mixed solutions of type V collagen and type I collagen in various ratios. They were incubated at 37 degrees C for 1 hour and negatively stained with 0.5% uranyl acetate (pH 4.4) at 37 degrees C. The specimens, seen by electron microscopy, were fibrils with a D-periodic banding pattern. Axial electron density profiles of collagen fibrils were obtained from selected electron micrographs by densitometric tracing. The slit width corresponded to 1.5 nm. The relative electron densities of overlap region vs. hole region were lower than 20% in fine fibrils containing a significant amount of type V collagen. It is suggested that the overlap region of such collagen fibrils may be loosely packed, being accessible to uranyl acetate, or the hole region may be filled by larger non-collagenous portions of type V collagen, resulting in loss of the light and dark alternation. Six to 8 white transverse lines were discerned per period and labeled consecutively with Arabic numerals. White lines 2 and 5 tended to merge with lines 1 and 4, respectively, in collagen fibrils formed from a solution containing a significant amount of type I collagen or pure type I collagen. The eight white lines corresponded to c2, c1, b2, b1, a4, a1, e1 and d with reference to their locations in the D-period. The locations of white lines in collagen fibrils which contain significant amount of type V collagen were identical with those in type I collagen fibrils. This is consistent with the primary structure that the axial distribution of charged amino acids in type V collagen is quite similar to that in type I collagen.