SEARCH · PubMed Health

Results for “Collagen Type IV”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources

PubMed2000

Characterization of hydra type IV collagen. Type IV collagen is essential for head regeneration and its expression is up-regulated upon exposure to glucose.

Hydra vulgaris mesoglea is a primitive basement membrane that also exhibits some features of an interstitial matrix. We have characterized cDNAs that encode the full-length hydra alpha1(IV) chain. The 5169-base pair transcript encodes a protein of 1723 amino acids, including an interrupted 1455-residue collagenous domain and a 228-residue C-terminal noncollagenous domain. N-terminal sequence analyses of collagen IV peptides suggest the molecule is homotrimeric. Denatured hydra type IV collagen protein occurs as dimers and higher order aggregates held together by nonreducible cross-links. Hydra collagen IV exhibits no functional evidence for the presence of a 7 S domain. Type IV collagen is expressed by the ectoderm along the entire longitudinal axis of the animal but is most intense at the base of the tentacles at the site of battery cell transdifferentiation. Antisense studies show that inhibition of collagen IV translation causes a blockage in head regeneration, indicating its importance in normal hydra development. Exposure of adult hydra to 15 mm glucose resulted in up-regulation of type IV collagen mRNA levels within 48 h and significant thickening of the mesoglea within 14 days, suggesting that basement membrane thickening seen in diabetes may be, in evolutionary terms, an ancient glucose-mediated response.

Amino Acid Sequence↗

PubMed2002

Type IV collagen, type IV collagenase activity and ability of cell proliferation in human thyroid tumours.

BACKGROUND: The processes of malignant tumour invasion and metastasis are known to include the destruction of cell stroma and vascular basement membrane. It has been suggested that type IV collagenase degrades type IV collagen, a main component of the basement membrane. METHODS: In our study, type IV collagenase activity in human thyroid tumours was measured by the Liotta method. The degree of destruction of diseased regions of thyroid tumours was immunohistochemically determined by anti-type IV collagen antibody staining. Cell proliferation in the tumours was estimated using anti-proliferating cell nuclear antigen (PCNA) and epidermal growth factor receptor (EGFR). RESULTS: T4 thyroid carcinomas with higher type IV collagenase activity and very weak type IV discontinuous immunostaining for type IV collagen of follicular basement membranes, exhibited many PCNA or EGFR positive cells. In benign tumours, normofollicular- or macrofollicular-type tumours with low type IV collagenase activity showed few PCNA and EGFR positive cells and intact type IV collagen of basement membranes, as seen in normal thyroids. Conversely, an atypical adenoma with higher type IV collagenase activity showed many PCNA and EGFR positive cells and weak type IV discontinuous immunostaining for type IV collagen, as in thyroid carcinomas. CONCLUSION: These findings suggest that staining for type IV collagen and type IV collagenase activity reflect the ability of cell proliferation, and help predict the aggressiveness of invasion and metastasis in human thyroid tumours.

Cell Division↗

PubMed1989

Distribution of laminin, collagen type IV, collagen type I, and fibronectin in chicken cardiac jelly/basement membrane.

Light microscopic immunolabeling studies were designed to identify and locate structural components within the cell-free extracellular matrix which lies between the embryonic endocardial and myocardial tubes. Affinity-purified antibodies were used to examine stage 15-22 embryonic chicken hearts. Specimens were immunolabeled by using three different methodologies: 1) postembedding labeling of 10 microns cryostat sections, 2) preembedding labeling (en bloc) of whole hearts, and 3) postembedding labeling of ethanol/acetic acid-fixed paraffin sections. Our results establish the spatial distribution of collagen type I and demonstrate for the first time the presence of collagen type IV and laminin in the myocardial-basement-membrane/cardiac jelly.

Animals↗

PubMed1993

Specificity of Goodpasture autoantibodies for the recombinant noncollagenous domains of human type IV collagen.

Type IV collagen has recently emerged as a family composed of five known chains (alpha 1-alpha 5), each of which contains a carboxyl-terminal noncollagenous domain (NC1) of approximately 230 amino acids. The NC1 domain of the alpha 3(IV) chain is the probable target for autoantibodies in patients with Goodpasture syndrome (GP), as evidenced from studies employing bovine type IV collagen. In the present experiments, the specificity of GP antibodies for the five NC1 domains of human type IV collagen was determined by using recombinant NC1 domains as the antigen. cDNAs encoding each NC1 domain were expressed in E. coli as fusion proteins with a 6-histidine amino-terminal leader. The recombinant NC1 monomers r alpha 1(IV), r alpha 2(IV), r alpha 3(IV), r alpha 4(IV), and r alpha 5(IV) were purified by affinity chromatography to the fusion protein using a nickel resin column, and then characterized by electrophoresis and immunoblot analysis using chain-specific peptide antibodies. The specificity of GP antibodies from four patients to these recombinant proteins was then further evaluated by immunoblot analysis and enzyme-linked immunosorbent assay measurements. The GP antibodies reacted strongly with the r alpha 3(IV) NC1 domain but were not reactive when tested against the other four recombinant monomers. In contrast, neither antisera from patients with two other forms of autoimmune disease (anti-tubular basement membrane disease and Wegener's syndrome) nor normal control sera bound to any of the recombinant NC1 moieties. These results unambiguously establish that GP antibodies are specifically targeted to the NC1 domain of the alpha 3(IV) chain of human type IV collagen. The findings also establish a methodology for large scale preparation of r alpha 3(IV) NC1 domain for use in diagnostic tests and development of therapeutic procedures and offer a strategy for the elucidation of a more complete GP epitope by site-directed mutagenesis.

Amino Acid Sequence↗

PubMed1988

The effect of nonenzymatic glucosylation on the binding of the main noncollagenous NC1 domain to type IV collagen.

Type IV collagen has the ability to self-assemble by amino end, carboxyl end, and lateral associations to complex network-like structures which can be visualized by rotary shadowing. The main noncollagenous NC1 domain which is located at the carboxyl end of type IV collagen molecules binds to itself to form dimers and also binds along the length of type IV collagen. The latter binding initiates lateral assembly. Following in vitro nonenzymatic glucosylation of the isolated NC1 domain, binding to the helix-rich domain of type IV collagen was impaired. In turbidity experiments, the nonenzymatically glucosylated NC1 domain minimally suppressed the development of turbidity of collagen solutions when compared to control NC1 domain. In rotary shadowing experiments nonenzymatically glucosylated NC1 domain did not significantly inhibit lateral associations or networks formed by type IV collagen, whereas control NC1 domain caused a drastic decrease in laterally assembled structures. These data suggest that nonenzymatic glucosylation of the NC1 domain may interfere with normal assembly of type IV collagen in diabetes mellitus and may be related to abnormal functions of basement membranes in this pathological condition.

Animals↗

PubMed1990

Identification of the cleavage sites by a hemorrhagic metalloproteinase in type IV collagen.

Type IV collagen, solubilized from Engelbreth-Holm-Swarm (EHS) tumor basement membranes is digested by a hemorrhagic metalloproteinase, Ht-e, isolated from the crude venom of the Western Diamondback rattlesnake, Crotalus atrox. The major proteolytic products have Mr 141,000, 132,000, 87,000, 71,000, 33,000 and approximately 18,000 as estimated by SDS-gel electrophoresis of pepsinized type IV collagen fragments. Sequence analysis of the digestion products reveal that the Mr 141,000, 71,000 and approximately 18,000 band are derived from the alpha 1(IV) chains and the Mr 132,000, 87,000 and 33,000 bands are derived from the alpha 2(IV) chain. The products are stable over 72-hour incubation periods. The cleavage sites on the alpha 1(IV) and alpha 2(IV) chains are not identical. The alpha 1(IV) chains are cleaved in a pepsin susceptible triplet interruption region of the triple helix at position Ala258-Gln259. The alpha 2(IV) chain is cleaved in the triple helical region near the NC2 domain at the Gly191-Leu192 peptide bond. Isolated hexameric NC1 globular domains of type IV collagen are not digested by Ht-e. The present study demonstrates that the venom hemorrhagic metalloproteinase Ht-e has type IV collagenolytic activity. The triple helix of the type IV collagen molecule is cleaved in a region located immediately carboxyl to the flexible NC2 domain. The degradation by Ht-e of type IV collagen, a major component of basement membranes which forms the scaffold of this extracellular structure, may account in part for the hemorrhagic activity of this toxin.

Amino Acid Sequence↗

PubMed1984

Cross-linking in type IV collagen.

Type IV collagen could not be extracted from human placenta using 6M-urea containing 10mM-dithiothreitol, indicating that the type IV molecule is stabilized within the basement membrane by covalent cross-links. However, various forms of type IV collagen molecule were extractable by means of increasingly severe proteolytic conditions. Type IV collagen tetramers ('spiders') lacking only the C-terminal globular region (NC1) were further digested to the 'long-form' 7S fragment and an assortment of helical rod-like molecules derived from the 'leg' region. These molecules were separated by salt fractionation and examined by rotary-shadowing electron microscopy. Isolation of these fractions from placenta which had been reduced with NaB3H4 revealed that both the 7S (N-terminal) and C-terminal regions contained significant proportions of reducible lysine-derived cross-links. These cross-links were shown to be exclusively the stable oxo-imine hydroxylysino-5-oxonorleucine. The number of the cross-links per molecule was significantly lower than might be expected in order to fully stabilize the molecule. These results suggest that the keto-imine cross-links in type IV collagen have been stabilized in part by conversion into an unknown non-reducible form, although a sensitive immunoassay failed to show the presence of any pyridinoline. Comparison with the fibrous collagen from placenta suggested that the rate of this conversion is much greater in basement-membrane collagen.

Basement Membrane↗

PubMed2002

Synthesis of heterotrimeric collagen peptides containing the alpha1beta1 integrin recognition site of collagen type IV.

Collagen type IV provides a biomechanically stable scaffold into which the other constituents of basement membranes are incorporated, but it also plays an important role in cell adhesion. This occurs with collagen type IV mainly via the alpha1beta1 integrin, and the proposed epitope involved in this type of collagen/integrin interaction corresponds to a non-sequential R/Xaa/D motif, where the arginine and aspartate residues are provided by the alpha2 and alpha1 chains of the collagen molecule, respectively. Since the stagger of the three alpha chains in native collagen type IV is still unknown and different alignments of the chains lead to different spatial epitopes, two heterotrimeric collagen peptides containing the natural 457-469 sequences of the cell adhesion site were synthesized in which the single chains were assembled via disulfide bonds into the two most plausible alpha1alpha2alpha1' and alpha2alpha1alpha1' registers. The differentiated triple-helical stabilities of the two heterotrimers suggest a significant structural role of the chain register in collagen, although the binding to alpha1beta1 integrin is apparently less affected as indicated by preliminary experiments.

Amino Acid Sequence↗

PubMed1997

[Role of type IV collagene and type IV collagenase in the invasion and metastasis of salivary adenoid cystic carcinoma].

Using immunohistochemical ABC method, the authors studied the distribution of type IV collagen and type IV collagenase in 25 cases ACC. The result showed type IV collagen was found in vascular and epithelial basement membrance, and in partly cyst of sieve-like and tubular pattern, and in cytoplasm of tumor cell. Type IV collagenase was detected in membrance and cytoplasm of tumor cell. Expression of type IV collagen and type IV collagenase were correlated with pathologic type, TNM stage and metastasis. Much positive staining of type IV collagen was found in sieve-tubular pattern, early stage of TNM and without metastasis, but much positive staining of type IV collagenase was found in solid pattern, later stage of TNM and metastasis. The result suggested that the loss of type IV collagen and over-expression of type IV collagenase may be markers of malignance of ACC.

Biomarkers, Tumor↗

PubMed1989

Malotilate prevents accumulation of type III pN-collagen, type IV collagen, and laminin in carbon tetrachloride-induced pulmonary fibrosis in rats.

Orally administered malotilate was studied as a protective antifibrotic agent with respect to experimentally induced pulmonary fibrosis in rats using immunohistochemical methods. Specific antibodies raised in rabbits against the aminoterminal propeptide of human type III procollagen and against two basement membrane proteins, the 7S domain of human type IV collagen and the P1 fragment of human laminin, were used for the immunohistochemical analysis, and the result was confirmed by morphometry. Intraperitoneally injected carbon tetrachloride significantly increased the volume densities of reticulin fibers, type III pN-collagen, type IV collagen, and laminin, whereas treatment with malotilate completely normalized these. Binding of the antibodies to rat antigens was also demonstrated by immunoelectron microscopy in which the collagen fibers with a typical periodic pattern were labeled positively with rabbit antitype III procollagen, whereas the amorphous basement membrane material reacted positively with rabbit antitype IV collagen and antilaminin, indicating good, specific cross-reactivity between these antibodies and the rat antigens. It is concluded that malotilate prevents the accumulation of type III pN-collagen and two basement membrane proteins, type IV collagen and laminin, in experimental pulmonary fibrosis, and can potentially be developed to provide a useful drug for preventing pulmonary fibrosis in humans.

Animals↗

PubMed1998

Equine laminitis basement membrane pathology: loss of type IV collagen, type VII collagen and laminin immunostaining.

Disintegration of the basement membrane (BM) of the equine hoof lamellae and failure of the BM to remain attached to the basal cells of the secondary epidermal lamellae (SEL) is one of the earliest pathological events to occur in acute laminitis. Changes in the lamellar basement membrane were investigated by immunolabelling the key structural components of the BM, type IV collagen, type VII collagen and laminin in the lamellar BM of horses 48 h after the induction of laminitis. Lamellar tissues were harvested from 2 normal horses and 2 horses with acute laminitis. Immunostaining with antibody raised against human epitopes for type IV collagen, type VII collagen and laminin successfully stained the basement membranes of horse hoof lamellar tissues. Vascular tissue did not immunostain with type VII collagen antibody. Normal BM stained as a fine dark brown line and the lamellar BM was adhered to the basal cells of the SELs with no evidence of lamellar separation. At least 2 changes to the lamellar BM occurred in acute laminitis: loss of attachment of lamellar epidermal basal cells to their underlying BM and disintegration of the lamellar BM. In some sections from feet affected by acute laminitis, there was widespread separation of the SELs from their BM without loss of BM immunostaining and in others there was extensive loss of BM immunostaining. In lesions characterised by lamellar separation, the epidermal basal cells at the tips of the primary epidermal lamellae appeared to have slipped away from their BM and were an amorphous clump of epidermal cells devoid of immunostained BM. The BM from which they had separated remained in its original position in the dermis and was clearly outlined by all 3 antibodies. In other areas, however, virtually all the BM immunoreactivity at the PEL tips was absent. Only the occasional distorted SEL tip and fragments of BM retained sufficient immunostaining to allow anatomical identification. Numerous polymorphonuclear leucocytes (PMNs) invariably surrounded the tips of lamellae showing large scale loss of immunoreactivity and many PMNs had penetrated the lamellar BM and were within the epidermal compartments. PMNs were less frequent in the midlamellar region. Immunostaining of the BM of many SELs was absent in the midlamellar region. In some lamellae loss of BM immunostaining had occurred only at the bases of the SELs and fragments of immunostained BM were present in the zones of lysed BM suggesting that BM lysis was incomplete at the time of tissue fixation. In other lamellae, lysis of the BM was complete; there was no immunostained BM between SELs and the bulk of the epidermal cells of each PEL were an amorphous column of cells on either side of the central keratinised axis of the PEL. The lamellar BM which remained appeared as immunostained strands of unattached BM along the edges of the PDLs. Activation of BM degrading metalloproteinases (MMPs) occurs in acute laminitis and it seems likely that uncontrolled MMP activity is responsible for the loss and disorganisation of lamellar BM demonstrated in this study.

Acute Disease↗

PubMed1997

Distribution of fibronectin, type I collagen, type IV collagen, and laminin in the cardiac jelly of the mouse embryonic heart with retinoic acid-induced complete transposition of the great arteries.

BACKGROUND: In the mouse model of complete transposition of the great arteries (TGA) produced by all-trans retinoic acid (RA), parietal and septal ridges in the outflow tract (OT) are hypoplastic. At first, these ridges are generated by an expanded cardiac jelly (mainly myocardial basement membrane). Thereafter, endothelial cells delaminate and invade into the adjacent cardiac jelly to form endocardial cushion tissue (formation of cushion ridge). During cushion tissue formation, basement membrane antigens play an important role in the regulation of this endothelial-mesenchymal transformation. METHODS: To examine whether the myocardial basement membrane components are altered in the RA-treated heart OT, immunohistochemistry for fibronectin, type I collagen, type IV collagen, and laminin was carried out in mouse embryonic hearts at 9.5 and 10.5 ED (embryonic day; vaginal plug = day 0) with or without prior exposure to RA. RESULTS: Particulate/fibrillar fibronectin and fibrillar type I collagen were observed in the thick cardiac jelly of the control heart at the onset of mesenchymal formation. In the RA-treated heart, an intermittent patchy staining for fibronectin and a sparse distribution of type I collagen were observed in the thin cardiac jelly. Laminin and type IV collagen were distributed continuously on the basal surface (layer adjacent to the basal plasma membrane) of endocardium and myocardium in both control and RA-treated hearts. CONCLUSIONS: The alterations in the antigens of the myocardial basement membrane (cardiac jelly) may be responsible for the hypoplasticity of parietal and septal ridges that characterizes RA-induced TGA morphology. This may be one of the reasons why mesenchymal cell formation is inhibited in the RA-induced TGA.

Animals↗

PubMed1995

Expression of basement membrane type IV collagen and type IV collagenases (MMP-2 and MMP-9) in human fetal teeth.

Formation and degradation of dental basement membrane (BM) are important for tooth development. Data on the expression of genes for type IV collagen (the major structural component of the BM) and type IV collagenases [MMP-2 (72 kDa) and MMP-9 (92 kDa)], enzymes that degrade type IV collagen during human tooth development, are lacking. We studied expression of type IV collagen and the MMP-2 and MMP-9 in human fetal teeth (from the 13th to the 20th gestational weeks, covering cap stage through early hard tissue formation). During cap and bell stages, in situ hybridization located transcripts for alpha 1 type IV collagen chain in the fibroblasts surrounding the enamel organ. No alpha 1 type IV collagen chain mRNA was detected in tooth germ epithelium or dental papilla. However, type IV collagen immunoreactivity was observed in BM underlying the dental epithelium up to the appositional stage. Transcripts for MMP-2 were located mostly in the cells of the dental papilla and follicle. Transient expression of MMP-2 mRNA was observed in the inner enamel epithelium of late cap/early bell-stage teeth. During early apposition, a high level of MMP-2 was confined to secretory odontoblasts. Transcripts for MMP-9 were detected by the sensitive reverse-transcription polymerase chain reaction (RT-PCR) in developing teeth. Thus, in dental BM, alpha 1 type IV collagen chain may be of mesenchymal cell origin. Further, MMP-2 but not MMP-9 may participate in remodeling and degradation of BM during human tooth morphogenesis.

Antisense Elements (Genetics)↗

PubMed2006

Distribution of extracellular matrix proteins type I collagen, type IV collagen, fibronectin, and laminin in mouse folliculogenesis.

The extracellular matrix (ECM) plays a prominent role in ovarian function by participating in processes such as cell migration, proliferation, growth, and development. Although some of these signaling processes have been characterized in the mouse, the relative quantity and distribution of ECM proteins within developing follicles of the ovary have not been characterized. This study uses immunohistochemistry and real-time PCR to characterize the ECM components type I collagen, type IV collagen, fibronectin, and laminin in the mouse ovary according to follicle stage and cellular compartment. Collagen I was present throughout the ovary, with higher concentrations in the ovarian surface epithelium and follicular compartments. Collagen IV was abundant in the theca cell compartment with low-level expression in the stroma and granulosa cells. The distribution of collagen was consistent throughout follicle maturation. Fibronectin staining in the stroma and theca cell compartment increased throughout follicle development, while staining in the granulosa cell compartment decreased. Heavy staining was also observed in the follicular fluid of antral follicles. Laminin was localized primarily to the theca cell compartment, with a defined ring at the exterior of the follicular granulosa cells marking the basement membrane. Low levels of laminin were also apparent in the stroma and granulosa cell compartment. Taken together, the ECM content of the mouse ovary changes during follicular development and reveals a distinct spatial and temporal pattern. This understanding of ECM composition and distribution can be used in the basic studies of ECM function during follicle development, and could aid in the development of in vitro systems for follicle growth.

Animals↗

PubMed1989

The human embryo produces basement membrane collagen (type IV collagen)-degrading protease activity.

The biochemical basis and mechanism of embryo implantation is poorly understood. The human embryo has to penetrate the endometrial basement membrane and the thick decidual wall during implantation, a process which resembles the active spreading of invasive tumour cells where the degradation of type IV collagen (basement membrane collagen) plays an important role. This study reports that human embryos produce type IV collagen-degrading enzyme activity and the secretion of this enzyme increases with time in culture. The type IV collagen-degrading enzyme activity might facilitate the penetration of the embryo through the decidua, thus emphasizing an active role of the embryo in implantation. On the other hand, unfertilized oocytes secrete low, stable amounts of type IV collagen-degrading enzyme activity in vitro. It was also found that follicular granulosa cells secrete high amounts of type IV collagenolytic activity in culture. It has been previously shown that there is a pre-ovulatory peak in type IV collagenolytic activity in follicular fluid, and it can be assumed that the appearance of this enzyme in the follicular fluid is probably connected to follicular rupture and that it is produced by granulosa cells.

Basement Membrane↗

PubMed1986

Comparison of non-collagenous type IV collagen components in the human glomerulus and EHS tumor.

A method for the isolation of the NC1 domain of type IV collagen has been developed using the EHS sarcoma, a basement membrane-producing mouse tumor. This NC1 domain has been compared to the NC1 of human glomerular basement membrane (hGBM) to assess its usefulness in the biochemical characterization of the Goodpasture antigen which is associated with NC1. Both NC1 isolates appeared to migrate by gel filtration as hexamers (Mr 160,000) and in SDS-polyacrylamide gel electrophoresis as dimers and monomers (Mr 54,000 and 26,000), and were shown to share biochemical identity by amino acid analysis. The hGBM NC1 showed greater complexity in the monomer region, and when compared by two-dimensional gel electrophoresis was found to contain more components in both regions than EHS NC1. Anti-GBM autoantibodies from patients with Goodpasture's syndrome reacted with the EHS NC1 by immunoblotting of two-dimensional gels. The EHS NC1 isolated by reverse phase HPLC partially inhibited the reactivity of the anti-GBM autoantibodies against hGBM NC1 by inhibition ELISA assay. Reverse phase HPLC elution of EHS and hGBM NC1 showed differences in subunit composition and interaction; complete dissociation of the EHS monomers and dimers in 0.1% trifluoroacetic acid was observed, whereas hGBM monomers and dimers eluted together. Rotary shadowing of hGBM NC1 domains revealed size heterogeneity of globular domains, compared with greater uniformity of EHS NC1 hexamers. We conclude that EHS NC1 contains an epitope(s) that is reactive with human autoantibodies to hGBM NC1. However, the immune response in Goodpasture's syndrome may involve antibodies directed against epitopes which are present in greater density and on a more complex array of peptides in the hGBM NC1 than in EHS NC1.

Amino Acids↗

PubMed1990

Comparison of non-collagenous type IV collagen subunits in human glomerular basement membrane, alveolar basement membrane, and placenta.

This study examines the similarities and differences in the noncollagenous domain (NC1) of type IV collagen from human glomerular basement membrane (hGBM), alveolar basement membrane (hABM), and placenta (hPBM). Following collagenase digestion, NC1 domain was isolated on Bio-Gel A-0.5m or by cation exchange chromatography on S-Sepharose. NC1 from each source was characterized by SDS PAGE, and two dimension NEPHGE/SDS PAGE. Immunoblotting and ELISA inhibition was performed using antibody probes specific for M28 , M28+, M26 and M24 monomer subunits of human NC1. It was observed that all NC1 subunits were present in hGBM and hABM derived material, however M28 and M28+ monomers were absent in hPBM NC1. These findings indicate that while alpha 1(IV) and alpha 2(IV) collagen chains are present in hGBM, hABM and hPBM, alpha 3(IV) and alpha 4(IV) collagen chains are only found in hGBM and hABM but are absent in hPBM. It can now be appreciated that heterogeneity of alpha (IV) chain composition exists in basement membranes from various organs.

Basement Membrane↗

PubMed1997

Type VI collagen anchors endothelial basement membranes by interacting with type IV collagen.

Type VI collagen filaments are found associated with interstitial collagen fibers, around cells, and in contact with endothelial basement membranes. To identify type VI collagen binding proteins, the amino-terminal domains of the alpha1(VI) and alpha2(VI) chains and a part of the carboxyl-terminal domain of the alpha3(VI) chain were used as bait in a yeast two-hybrid system to screen a human placenta library. Eight persistently positive clones were identified, two coding the known matrix proteins fibronectin and basement membrane type IV collagen and the rest coding new proteins. The amino-terminal domain of alpha1(VI) was shown to interact with the carboxyl-terminal globular domain of type IV collagen. The specificity of this interaction was further studied using the yeast two-hybrid system in a one-on-one format and confirmed by using isolated protein domains in immunoprecipitation, affinity blots, and enzyme-linked immunosorbent assay-based binding studies. Co-distribution of type VI and type IV collagens in human muscle was demonstrated using double labeling immunofluorescent microscopy and immunoelectron microscopy. The strong interaction of type VI collagen filaments with basement membrane collagen provided a possible molecular pathogenesis for the heritable disorder Bethlem myopathy.

Adult↗