Isolation and partial characterization of the entire human pro alpha 1(II) collagen gene

Sheep gene mapping: synteny between COL2A1 and the LDHB-PEPB-TPI-GAPD-LALBA-IGF1 group

DNA extracted from 21 hamster-sheep hybrid cell lines was subjected, after Southern blotting, to hybridization with a type-II alpha 1 collagen genomic probe (COL2A1). The corresponding locus was found to be syntenic with the LDHB-PEPB-TPI-GAPD-LALBA-IGF1 group in sheep.

Serum-free growth medium sustains commitment of human articular chondrocyte through maintenance of Sox9 expression

Human articular cartilage heals poorly in adults and current surgical procedures do not provide long-term repair. Cell therapy and tissue engineering could become the treatment of choice, but suffer a major limitation as chondrocytes in vitro lose the differentiated phenotype. In vivo, the chondrogenic lineage is specified by transcription factor Sox9. Thus, cell-based therapy could be successful if Sox9 expression and chondrogenic commitment of the expanded cells were preserved. To achieve this goal, we developed a serum-free medium that supports cell proliferation and preserves the differentiation potential. Indeed, expression of Sox9 is maintained when the conventionally used serum is substituted for by this defined supplement. Spontaneous cartilage formation after expansion in serum-free medium is obtained in vitro in a high-density pellet culture and confirmed in vivo in a functional assay in immunodeficient mice. By contrast, cells grown in serum lose the expression of Sox9 and fail to reform cartilage both in vitro and in vivo unless they are rescued by chondrogenic inducers such as transforming growth factor beta(1) and dexamethasone. Our data emphasize the importance of the microenvironment in modulating commitment, plasticity, and phenotype of chondrocytes, and provide an experimental system to study their physiological or pathological metabolism in a controlled context.

Type II Collagen Accumulation in Overlying Dermo-Epidermal Junction of Pilomatricoma Is Mediated by Bone Morphogenetic Protein 2 and 4

Pilomatricoma consists of the cells differentiating towards hair matrix cells. Immunohistochemical study revealed the deposition of type II collagen in the overlying dermo-epidermal junction (DEJ) of this benign tumor. Proalpha(1)(II) mRNA was detected by RT-PCR in the overlying epidermal layer but not in the dermal layer prepared from the lesional skin of pilomatricoma. The neutral salt-soluble proteins extracted from the tumor of pilomatricoma induced proalpha(1)(II) mRNA in the cultured human keratinocytes but not in the cultured dermal fibroblasts. Bone morphogenetic protein 2 or 4 (BMP2 or 4) was immunohistochemically detected in some shadow cells of pilomatricoma. Recombinant BMP2 and BMP4 were found to induce proalpha(1)(II) mRNA concentration dependently in the cultured human keratinocytes but not in the cultured fibroblasts. Proalpha(1)(II) mRNA induced by BMP2 and in cultured keratinocytes contained exon 2, indicating that the mRNA species is non-chondrogenic type IIA form. The results strongly suggest that BMP2 or 4 expressed in pilomatricoma is responsible for the induction of proalpha(1)(II) collagen mRNA in the overlying epidermal cells resulting in the deposition of type II collagen in the DEJ. When human keratinocytes were cultured on type II collagen substratum in vitro, the cell proliferation was accelerated at the early period of culture but was inhibited at the late period of culture, whereas the cell proliferation was persistently accelerated by type I or IV collagen substratum. Type II collagen deposition in the DEJ may potentially exert profound effects on keratinocyte proliferation and differentiation.

Expression of genes of type I and type II collagen in the formation and development of the blastema of regenerating newt limb

We cloned cDNAs of alpha1(I) and alpha1(II) collagen, and studied their expression profiles in regenerating limbs of newts, Cynops pyrrhogaster. The expression of the alpha1(I) gene was markedly up-regulated at the early bud stage of the blastema. In situ hybridization experiments revealed that the alpha1(I) gene was expressed in not only mesenchymal cells of the blastema, but also the basal cells of the wound epidermis at the wound healing stage when the epidermal basement membrane was absent. This unique expression continued until 21 days (late bud stage), while the basement membrane began to form at 14 days. These results indicate biochemical differences between the wound and normal epidermis, and suggest the direct involvement of the former in the synthesis of blastemal matrices of type I collagen. Actually, immunohistochemistry revealed that type I collagen began to be deposited beneath the wound epidermis at 8 days, and accumulated there and around blastemal mesenchymal cells at 14 to 21 days. Undifferentiated mesenchymal cells associated with the amputated muscle fibers actively expressed the alpha1(I) gene. Mesenchymal cells in the central region of blastemas deposited type I collagen fibers around them. Concomitantly with the appearance of prechondrocytes, the alpha1(II) collagen gene became activated. The present study clearly shows that the expression of the genes of both type I and type II collagen in blastemal cells is temporally and regionally well-regulated in a cooperative manner. Dev Dyn 1999;216:59-71.

Cell-type specific and thyroid hormone-dependent expression of genes of alpha1(I) and alpha2(I) collagen in intestine during amphibian metamorphosis

Both the epithelium and the mesenchyme of the larval small intestine of anurans undergoes metamorphic conversion into the adult counterparts. The conversion of the mesenchyme has been poorly understood especially at the molecular level, whereas the changes of the epithelium have been extensively studied. The present study investigated the metamorphic changes of the mesenchyme of tadpoles of bullfrog, Rana catesbeiana, focusing on the expression of genes of type I collagen. By using the cDNA clones coding for a 1(I) and a 2(I) collagen as probes, expression of each collagen gene was examined. These genes were drastically up-regulated at the climax period of spontaneous metamorphosis, which was precociously mimicked by treating tadpoles with thyroid hormone. The increased expression of these genes at the climax stage was well correlated with the conversion of the thin larval mesenchyme to more thick and dense adult connective tissues of the intestine. In situ hybridization identified the fibroblasts that were actively expressing the collagen genes and, therefore, were thought to be responsible for the remodeling. These results strongly suggest that the expression of type I collagen genes is regulated during the intestinal remodeling in a cell-type specific and thyroid hormone-dependent manner.

Cloning of an annelid fibrillar-collagen gene and phylogenetic analysis of vertebrate and invertebrate collagens

Arenicola marina possesses cuticular and interstitial collagens, which are mostly synthesised by its epidermis. A cDNA library was constructed from the body wall. This annelid cDNA library was screened with a sea-urchin-collagen cDNA probe, and several overlapping clones were isolated. Nucleotide sequencing of these clones revealed an open reading frame of 2052 nucleotides. The translation product exhibits a triple helical domain of 138 Gly-Xaa-Yaa repeats followed by a 269-residue-long C-terminal non-collagenous domain (C-propeptide). The triple helical domain exhibits an imperfection that has been previously described in a peptide produced by cyanogen bromide digestion (CNBr peptide) of A. marina interstitial collagen. This imperfection occurs at the same place in the interstitial collagen of the vestimentiferan Riftia pachyptila. This identifies the clone as coding for the C-terminal part of a fibrillar collagen chain. It was called FAm1alpha, for fibrillar collagen 1alpha chain of A. marina. The non-collagenous domain possesses a structure similar to carboxy-terminal propeptides of fibrillar pro-alpha chains. Only six conserved cysteine residues are observed in A. marina compared with seven or eight in all other known C-propeptides. This provides information on the importance of disulfide bonds in C-propeptide interactions and in the collagen-assembly process. Phylogenetic studies indicate that the fibrillar collagen 1alpha chain of A. marina is homologous to the R. pachyptila interstitial collagen and that the FAm1alpha gene evolved independently from the other alpha-chain genes. Complementary analyses indicate that the vertebrate fibrillar collagen family is composed of two monophyletic subgroups with a specific position of the collagen type-V chains.

Seventeen copies of the human 37 kDa laminin receptor precursor/p40 ribosome-associated protein gene are processed pseudogenes arisen from retropositional events

A cDNA coding for a 37 kDa polypeptide has been identified in several species as both the potential precursor of the 67 kDa laminin receptor (37LRP) and a putative ribosome-associated protein (p40). Interestingly, increased expression of this polypeptide (37LRP/p40) is consistently observed in invasive and metastatic cancer cells and is associated with poor prognosis. Southern-blot analysis of human genomic DNA predicted multiple copies of the 37LRP/p40 gene. In this study, we report that the number of copies of this sequence in the human genome is 26 +/- 2. We have sequenced and analyzed 19 genomic clones corresponding to the 37LRP/p40 gene and found that they were all processed pseudogenes. They all lack intronic sequences and show multiple genetic alterations leading in some cases to the appearance of stop codons. Moreover, they all bear characteristic features of retroposons as the presence of a poly(A)-tail at their 3' end and short direct repeated flanking DNA sequences. None of the pseudogenes analyzed present cis-elements in their 5' flanking region such as TATA or GC boxes. Our date reveal that over 50% of the 37LRP/p40 gene copies are pseudogenes most probably generated by retropositional events. The finding of multiple pseudogenes for the 37LRP/p40 suggests that the accumulation of several copies of this gene might have given a survival advantage to the cell in the course of evolution.

Genetic aspects of familial osteoarthritis

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Autosomal dominant (Beukes) premature degenerative osteoarthropathy of the hip joint unlinked to COL2A1

Molecular investigations have been undertaken in several separate large South African families with autosomal dominant skeletal dysplasias in which premature degenerative osteoarthropathy of the hip joint was the major manifestation. There are sometimes additional minor changes in the spine and these conditions fall into the general spondyloepiphyseal dysplasia (SED) nosological category. In some kindreds, linkage between phenotype and the type II collagen gene (COL2A1) has been established, while in others there is no linkage. We have now completed molecular linkage investigations in an Afrikaner family named Beukes, in which 47 members in 6 generations have premature osteoarthropathy of the hip joint. A LOD score of minus infinity indicates that this condition is not the result of a defect of the COL2A1 gene.

Characterizations of sea urchin fibrillar collagen and its cDNA clone

Collagens were isolated from the adult test of the sea urchin species, Hemicentrotus pulcherrimus and Strongylocentrotus purpuratus, and their molecular properties were compared with those of Asthenosoma ijimai collagen. Collagens from H. pulcherrimus and S. purpuratus comprised two major alpha-chains (alpha 120 and alpha 90) and a minor chain (alpha 140), while collagen from A. ijimai contained four alpha-chains (alpha 1, alpha 2, alpha 3 and alpha 4). Based on their molecular and immunological properties, the alpha 90 chain of H. pulcherrimus and S. purpuratus, and the alpha 2 and alpha 4 chains of A. ijimai are grouped together, while the alpha 120 and alpha 140 chains of H. pulcherrimus and S. purpuratus, and the alpha 1 and alpha 3 chains of A. ijimai are classified into another group. It is likely that collagen molecules of sea urchins are heterotrimers composed of these two types of alpha-chains. A cDNA of collagen was cloned from the cDNA library prepared from mRNA of H. pulcherrimus test and denoted as Hpcol1. This clone contained sequences for uninterrupted triple helical domain (378 amino acids), carboxyl telopeptide (28 amino acids) and carboxyl propeptide (225 amino acids). This structure is characteristic for fibril-forming collagens and was shown to encode alpha 120 and alpha 140 chains of H. pulcherrimus collagen. Hpcol1-mRNA was expressed in embryos as early as the prism stage.

Synthesis of recombinant human procollagen II in a stably transfected tumour cell line (HT1080)

Apparently because the biosynthetic pathways involve eight or more highly specific post-translational enzymes, it has been difficult to obtain expression of genes for fibrillar collagens in recombinant systems. Here two constructs of the human gene for procollagen II (COL2A1) were prepared, one with about 0.5 kb of a promoter for a procollagen I gene (COL1A1) and the other with about 4 kb of the promoter for the procollagen II gene. The constructs, together with a neomycin-resistant gene, were transfected into a human tumour cell line (HT1080) that synthesizes the collagen IV found in basement membranes, but does not synthesize any fibrillar collagen. About two per 100 clones resistant to the neomycin analogue G418 synthesized and secreted human procollagen II. Milligram quantities of the recombinant procollagen II were readily isolated from the cultured medium. The recombinant procollagen II had the expected amino acid sequence as defined by nucleotide sequencing of mRNA-derived cDNA and the expected amino acid composition as defined by analysis of procollagen II that was converted into collagen II by digestion with procollagen N- and C-proteinases. Also, analysis of the carbohydrate content indicated that there was glycosylation of some of the hydroxylysine residues but no evidence of post-translational overmodification of the residues. In addition, the protein was shown to have a native conformation as assayed by a series of protease digestions. No essential differences were found between clones transfected with the COL2A1 gene construct containing the COL1A1 promoter and the similar construct containing the COL2A1 promoter in terms of number of clones synthesizing recombinant procollagen II and the levels of expression. With both constructs, the expression of the COL2A1 gene was closely related to copy number. The results demonstrated therefore that it is not essential to use a promoter for a gene normally expressed in a host cell in order to obtain gene copy-number-dependent expression of an exogenous collagen gene in stably transfected cells.

Spondyloepiphyseal dysplasia and precocious osteoarthritis in a family with an Arg75-->Cys mutation in the procollagen type II gene (COL2A1)

Direct sequencing of polymerase chain reaction (PCR)-amplified genomic DNA from a patient with spondyloepiphyseal dysplasia and precocious osteoarthritis revealed a single-base change in exon 11 of the type II procollagen gene (COL2A1), which produces an Arg-->Cys mutation in one allele. The proband is a member of a large Chilean kindred presenting with chondrodysplasia of the hips, knees, shoulders, elbows, and spine associated with severe, early-onset osteoarthritis. All affected individuals exhibit mildly short stature; in addition, five out of seven affected family members display shortened metacarpals or metatarsals. DNA from affected and unaffected family members was PCR-amplified and analysis of restriction digests of the products determined that the mutation segregated with the disease with a lod score of 2.2 at zero recombination. The mutation, which resides in the triple-helical region of type II procollagen at amino acid position 75, is the second example of an Arg-->Cys mutation in the COL2A1 gene in heritable cartilaginous disease and is the first example of a point mutation in the amino terminal region of the alpha 1(II) chain, that results in a spondyloepiphyseal dysplastic phenotype.

An inbred line of transgenic mice expressing an internally deleted gene for type II procollagen (COL2A1). Young mice have a variable phenotype of a chondrodysplasia and older mice have osteoarthritic changes in joints

Studies were carried out on a line of transgenic mice that expressed an internally deleted COL2A1 gene and developed a phenotype resembling human chondrodysplasias (Vandenberg et al. 1991. Proc. Natl. Acad. Sci. USA. 88:7640-7644. Marked differences in phenotype were observed with propagation of the mutated gene in an inbred strain of mice in that approximately 15% of the transgenic mice had a cleft palate and a lethal phenotype, whereas the remaining mice were difficult to distinguish from normal littermates. 1-d- and 3-mo-old transgenic mice that were viable showed microscopic signs of chondrodysplasia with reduced amounts of collagen fibrils in the cartilage matrix, dilatation of the rough surfaced endoplasmic reticulum in the chondrocytes, and decrease of optical path difference in polarized light microscopy. The transgenic mice also showed signs of disturbed growth as evidenced by lower body weight, lower length and weight of the femur, decreased bone collagen, decreased bone mineral, and decreased resistance of bone to breakage. Comparisons of mice ranging in age from 1 d to 15 mo demonstrated that there was decreasing evidence of a chondrodysplasia as the mice grew older. Instead, the most striking feature in the 15-mo-old mice were degenerative changes of articular cartilage similar to osteoarthritis.

Autoimmune recognition of cartilage collagens

Recent advances in basic research on the immune system and molecular biology of cartilage components have greatly increased our understanding of the role of autoimmunity in inflammatory diseases affecting joints, particularly rheumatoid arthritis. Many of these diseases are common and their complex pathogenesis probably involves a large number of genes polymorphic in the population as well as environmental factors. Characteristic features of inflammatory arthritis include expansion of the synovial tissue into a pannus containing lymphocytes and macrophages, autoimmune reactions against cartilage antigens, and erosion of cartilage. Since hyaline cartilage of the articular surfaces is the only structure within the joint known to contain joint-specific antigens this tissue is the prime suspect as the target of the autoimmune This review will first present the capacity of the immune system to discriminate between self and non-self structures, and then summarize our current understanding of the structures of cartilage collagens. Subsequently we will discuss how the immune system normally interacts with cartilage and how such interactions can lead to arthritis. We propose that collagen-induced arthritis (CIA) is valuable for understanding the autoimmune recognition of cartilage collagen which precedes the outbreak of arthritis and may perpetuate its chronicity, and serves as an animal model of rheumatoid arthritis.

Exclusion of type II and type VI procollagen gene mutations in a five-generation family with multiple epiphyseal dysplasia

We have studied a family with an autosomal dominant form of multiple epiphyseal dysplasia (MED) inherited through at least 5 generations. Bilateral deformity of the hips with subsequent degenerative arthritis was the most common and most severe change observed in the affected relatives. Abnormalities of the knees, ankles, and shoulders were also noted in some affected individuals. Radiological examination showed changes in affected joints consistent with epiphyseal dysplasia. In early stages, the articular surfaces appeared flattened or irregular in shape. In advanced stages, epiphyseal fragmentation, joint surface erosion, and extensive remodeling were observed. The abnormalities of the epiphyses suggested that the primary defect might be in a structural component of the epiphyseal cartilage matrix. The gene encoding type II collagen (COL2A1) was tested for genetic linkage to MED in this family by restriction fragment length polymorphism (RFLP) analysis. Recombination between COL2A1 and MED was observed, ruling out COL2A1 as the site of the mutation. The genes encoding the 3 chains of type VI collagen were also excluded on the basis of discordant inheritance. The disease in this family is therefore not the result of mutations in the genes encoding type II or type VI collagen.

Subregional mapping of 13 single-copy genes on the long arm of chromosome 12 by fluorescence in situ hybridization

Subregional localization of 13 single-copy DNA sequences previously assigned to the long arm of chromosome 12 has been performed using the fluorescence in situ hybridization (FISH) technique. The following order is suggested for the 13 mapped genes: cen-->COL2A1-->(VDR-D12S15)-->(D12S17-D12S4++ +-D12S14-D12S6)-->D12S8-->(IAPP-MGF- D12S7-D12S12)-->IGF1-->qter. Eight of the mapped genes clustered at two regions, one at 12q13 (D12S17-D12S4-D12S14-D12S6) and the other at 12q22 (IAPP-MGF-D12S7-D12S12). Our results show that single-copy DNA sequences as small as 500 bp can be successfully mapped by FISH.

The association of the human epsilon-globin gene with the nuclear matrix: a reconsideration

The association of the human epsilon-globin gene with the nuclear matrix was studied in erythroid and non-erythroid cell lines. Using a high salt method to prepare histone depleted nuclei we studied the association of variety of fragments covering a 7.8 kb region which contains the human epsilon-globin gene. We furthermore studied the association of a set of DNA fragments covering the 13 kb human G gamma/A gamma-globin gene domain, the 16 kb psi beta/delta-globin gene domain and the 10 kb beta-globin gene domain with the nuclear matrix of K562 and Raji cells. The results show that all fragments studied are easily released from the nuclear matrix, indicating no specific association. Summarizing our results we could say that a region starting 5.7 kb 5' to the human epsilon-globin gene and ending 4 kb 3' to the human beta-globin gene seems to contain no attachment sites with the nuclear matrix of both erythroid and non-erythroid cells.

Spondyloepiphyseal dysplasia in a Cape Town family: linkage with the gene for type II collagen (COL2A1)

A moderately severe form of autosomal dominant (AD) spondyloepiphyseal dysplasia (SED) has been documented in 14 individuals in 3 generations of a family in Cape Town, South Africa. Affected persons had a short trunk; radiographic investigations indicated that skeletal involvement was worst in the hips and spine. Linkage studies with restriction fragment length polymorphisms (RFLPs) associated with the COL2A1 gene and the phenotype yielded a maximal LOD score of 4.51 at theta = 0.00. This result suggests that the structural locus for type II collagen is primarily involved in the pathogenesis of this form of SED.

Structural analysis of the regulatory elements of the type-II procollagen gene. Conservation of promoter and first intron sequences between human and mouse

Transcription of the type-II procollagen gene (COL2A1) is very specifically restricted to a limited number of tissues, particularly cartilages. In order to identify transcription-control motifs we have sequenced the promoter region and the first intron of the human and mouse COL2A1 genes. With the assumption that these motifs should be well conserved during evolution, we have searched for potential elements important for the tissue-specific transcription of the COL2A1 gene by aligning the two sequences with each other and with the available rat type-II procollagen sequence for the promoter. With this approach we could identify specific evolutionarily well-conserved motifs in the promoter area. On the other hand, several suggested regulatory elements in the promoter region did not show evolutionary conservation. In the middle of the first intron we found a cluster of well-conserved transcription-control elements and we conclude that these conserved motifs most probably possess a significant function in the control of the tissue-specific transcription of the COL2A1 gene. We also describe locations of additional, highly conserved nucleotide stretches, which are good candidate regions in the search for binding sites of yet-uncharacterized cartilage-specific transcription regulators of the COL2A1 gene.

Localization of the expression of type I, II, III collagen, and aggrecan core protein genes in developing human articular cartilage

The expression of mRNAs for collagen types I, II, III and for aggrecan core protein was studied in developing human femoral cartilage by in situ hybridization, with special attention given to the cartilage covered by the perichondrium and to the articular surface. In parallel, the synthesis of the related proteins was monitored by immunohistochemistry. The cells metabolically active for type I and type III collagen expression were identified by hybridization using [32P]-labeled cDNA clones coding for human alpha 1(I) and alpha 1(III), respectively. Type II collagen and core protein mRNAs were detected by hybridization with specific [32P]-labeled oligonucleotide probes. In the femoral heads of one 22-week old fetus and of one newborn, our in situ hybridization and immunohistochemical analysis revealed that chondrocytes located immediately subjacent to the perichondrium produced collagen types I, II, III as well as aggrecan; whereas only type II collagen and aggrecan gene expression was detected deeper in the cartilage covered by the perichondrium. This observation supports the hypothesis that the inner cell layers of perichondrium are chondrogenic, with a transient state where cells express all the markers studied here. At the articular surface different patterns of expression were observed at the two developmental stages. After 22 weeks of fetal development only collagen types I and III were expressed by the surface zone cells while in the newborn cartilage, these cells expressed all the molecules studied (collagen types I, II, III and cartilage proteoglycan). At both ages the underlying cartilage cells expressed only the cartilage-specific molecules (type II collagen and aggrecan). Thus a progressive transformation of cartilaginous matrix occurs with time from the deep cartilage up to the surface by addition of new components, i.e. aggrecan and type II collagen. These results supplemented by an immunofluorescence analysis on 20-, 26- and 38-week old fetal femoral heads suggest that expression of collagen and aggrecan in the cartilage covered by the perichondrium and in the cartilage at the articular surface are subject to different regulatory mechanisms during development. Furthermore, the appearance of hybridizable core protein and type II collagen mRNAs at the articular surface, closely followed by the appearance of the proteins for which they code, indicates that core protein and type II collagen expression is regulated primarily at the transcriptional level in this region. Finally, the similar topography observed for the expression of these two proteins suggests that the genes for these two major constituents of cartilage matrix are coordinately regulated during growth of articular cartilage.

Detection of DNA sequence polymorphisms in human genomic DNA by using denaturing gradient gel blots

Denaturing gradient gel electrophoresis can detect sequence differences outside restriction-enzyme recognition sites. DNA sequence polymorphisms can be detected as restriction-fragment melting polymorphisms (RFMPs) in genomic DNA by using blots made from denaturing gradient gels. In contrast to the use of Southern blots to find sequence differences, denaturing gradient gel blots can detect differences almost anywhere, not just at 4-6-bp restriction-enzyme recognition sites. Human genomic DNA was digested with one of several randomly selected 4-bp recognition-site restriction enzymes, electrophoresed in denaturing gradient gels, and transferred to nylon membranes. The blots were hybridized with radioactive probes prepared from the factor VIII, type II collagen, insulin receptor, beta 2-adrenergic receptor, and 21-hydroxylase genes; in unrelated individuals, several RFMPs were found in fragments from every locus tested. No restriction map or sequence information was used to detect RFMPs. RFMPs can be used as genetic markers, because their alleles segregate in a Mendelian manner. Unlike most other methods for detecting DNA sequence polymorphisms, a genomic DNA blot made from one gel can be hybridized consecutively with many (30 or more) different probes.

Detection of sequence variants in the gene for human type II procollagen (COL2A1) by direct sequencing of polymerase chain reaction-amplified genomic DNA

The direct sequencing of the human type II procollagen (COL2A1) gene from polymerase chain reaction (PCR)-amplified genomic DNA is described. Thirty-two regions of the COL2A1 gene were asymmetrically amplified with intron primers which were specifically chosen to amplify a region spanning 500 to 800 bp of sequence encoding one or more exons and their accompanying intervening sequences. Primers for dideoxynucleotide sequencing of the PCR products were then designed to provide complete exon sequence information and to insure that intron:exon splice junction sequence data would be obtained. Amplification and sequencing reactions were performed on an automated workstation to facilitate the handling of multiple DNA templates. The procedure allowed efficient sequencing of over 25,000 bp of each allele of the COL2A1 gene per diploid genome. We used this method for the comparative analyses of COL2A1 sequences in DNA isolated from the blood of 42 unrelated individuals and we identified 21 neutral sequence variants in the gene. The sequence variations were confirmed by independent assays, including restriction enzyme digestion. The sequence variants described here will be important for identifying haplotypes of the type II procollagen gene that will be useful in defining a genetic etiology for diseases of cartilaginous tissues.

Marshall syndrome

We report on a mother and daughter with Marshall syndrome, with the Robin sequence present in the daughter. Results of our efforts to link this syndrome to a defect in type II collagen are reported. We compare and contrast Marshall syndrome with the Stickler syndrome, and propose that enough phenotypic overlap exists to suggest that they are probably allelic expressions of the same locus.

Expression of a partially deleted gene of human type II procollagen (COL2A1) in transgenic mice produces a chondrodysplasia

A minigene version of the human gene for type II procollagen (COL2A1) was prepared that lacked a large central region containing 12 of the 52 exons and therefore 291 of the 1523 codons of the gene. The construct was modeled after sporadic in-frame deletions of collagen genes that cause synthesis of shortened pro alpha chains that associate with normal pro alpha chains and thereby cause degradation of the shortened and normal pro alpha chains through a process called procollagen suicide. The gene construct was used to prepare five lines of transgenic mice expressing the minigene. A large proportion of the mice expressing the minigene developed a phenotype of a chondrodysplasia with dwarfism, short and thick limbs, a short snout, a cranial bulge, a cleft palate, and delayed mineralization of bone. A number of mice died shortly after birth. Microscopic examination of cartilage revealed decreased density and organization of collagen fibrils. In cultured chondrocytes from the transgenic mice, the minigene was expressed as shortened pro alpha 1(II) chains that were disulfide-linked to normal mouse pro alpha 1(II) chains. Therefore, the phenotype is probably explained by depletion of the endogenous mouse type II procollagen through the phenomenon of procollagen suicide.

Stop codon in the procollagen II gene (COL2A1) in a family with the Stickler syndrome (arthro-ophthalmopathy)

Linkage analysis with restriction fragment length polymorphisms for the gene for type II procollagen (COL2A1) was carried out in a family with the Stickler syndrome, or arthro-ophthalmopathy, an autosomal dominant disorder that affects the eyes, ears, joints, and skeleton. The analysis demonstrated linkage of the disease and COL2A1 with a logarithm-of-odds score of 1.51 at zero recombination. A newly developed procedure for preparing cosmid clones was employed to isolate the allele for type II procollagen that was linked to the disease. Analysis of over 7000 nucleotides of the gene revealed a single base mutation that altered a CG dinucleotide and converted the codon CGA for arginine at amino acid position alpha 1-732 to TGA, a stop codon. From previous work on procollagen biosynthesis, it is apparent that the truncated polypeptide synthesized from an allele with a stop codon at alpha 1-732 cannot participate in the assembly of type II procollagen, and therefore that the mutation would decrease synthesis of type II procollagen. It was not apparent, however, why the mutation produced marked changes in the eye, which contains only small amounts of type II collagen, but relatively mild effects on the many cartilaginous structures of the body that are rich in the same protein.

Mild spondyloepiphyseal dysplasia (Namaqualand type): genetic linkage to the type II collagen gene COL2A1

Namaqualand spondyloepiphyseal dysplasia (NSED) is a mild autosomal dominant form of spondyloepiphyseal dysplasia in which changes are maximal in the femoral capital epiphyses and the vertebral bodies. The condition is present in a large multigeneration South African family, and it is clinically important by virtue of severe progressive degenerative osteoarthropathy of the hip joint, which frequently necessitates prosthetic joint replacement in adulthood. Linkage studies using molecular markers have shown that the loci for the NSED and type II collagen genes are linked (LOD score 7.98 at a recombination fraction of .00).

Genomic organization of the human procollagen alpha 1(II) collagen gene

The nucleotide sequence of the human procollagen alpha 1(II) collagen gene extending from within the first intron through exon 15, and part of the 15th intron has been determined. This sequence analysis (7056 bases) identifies the intron/exon organization of the region of this gene encoding the N-propeptide and part of the triple-helical domain. Structural comparison of this with the genes of other human fibrillar collagens shows considerable diversity in terms of size and number of introns and exons that encodes the N-propeptide domain. Although the genomic structure of the human procollagen alpha 1(II) gene is quite different from the rat procollagen alpha 1(II) gene, the nucleotide coding sequences are 89% identical.

The mouse Col2a-1 gene is highly conserved and is linked to Int-1 on chromosome 15

Type II collagen is the major extracellular matrix component of cartilage and correct expression of the alpha 1(II) collagen gene is important for vertebrate skeletal development. In order to provide the basis for studying the control of type II collagen gene expression in embryogenesis and in mouse models of human connective tissue disease, the complete mouse Col2-a1 gene has been isolated in a single cosmid clone, cosMco1.2, and partially characterized. The gene is approximately 30 kb and is highly conserved in exon/intron structure and nucleotide and amino acid sequence (greater than 80% homology) when compared with the human, rat, bovine and chicken equivalents. A high degree of conservation was also found in the 5' flanking region of the rat, human and mouse alpha 1(II) collagen genes, including the presence of several G + C and C + T rich, direct repeat motifs. The sites of transcription start, termination codon and polyadenylation have also been identified. Unlike chicken, bovine and human, where polyA attachment is at a single site, for the mouse Col2a-1 gene two polyadenylation sites are utilized. Col2a-1 has also been localized by interspecies backcross analysis to the central portion of mouse Chromosome (Chr) 15, approximately 8 centiMorgans (cM) proximal of Int-1 and 18 cM distal of Myc. Col2a-1 is therefore included in a linkage group which is conserved on human Chr 12q.

Completion of the intron-exon structure of the gene for human type II procollagen (COL2A1): variations in the nucleotide sequences of the alleles from three chromosomes

A new procedure for preparing cosmid libraries was used to isolate three alleles for the human gene for type II procollagen (COL2A1). Over 20,000 bp of one allele were completely sequenced and over 10,000 bp of the two other alleles were sequenced. The data located and defined 26 exons and introns of the gene not previously analyzed. The results completed the structure of the gene except for the newly discovered exon 2A that undergoes alternative splicing (Ryan et al., 1990, Trans. Ann. Meet. Orthop. Res. Soc. 15:65). As a result, it is the most completely known structure of a gene for a human fibrillar collagen. The results confirm the previous impression that exon sizes are highly conserved among the genes for the three major fibrillar collagens. Comparison of clones from the three alleles defined five neutral variations in coding sequences and seven variations in the intron that also are probably neutral variations. The normal sequences and the variations in sequences will be important for identifying different alleles and haplotypes of the gene and for the analysis of genetic mutations in the gene that cause diseases of cartilage such as chondrodysplasias and osteoarthritis.

Spondyloepiphyseal dysplasia, mild autosomal dominant type is not due to primary defects of type II collagen

A mild autosomal dominant form of spondyloepiphyseal dysplasia (SED) is present in several generations of a South African family of English stock. This phenotype differs from that of any other previously described. Although type II collagen defects have been found in some families with SED congenita, the phenotype in our family showed discordant segregation with COL2A1 gene associated restriction fragment length polymorphisms (RFLPs), the markers for the structural locus of type II collagen. It is evident that the SED group of disorders is heterogeneous.

Efficient procedure for preparing cosmid libraries from microgram quantities of genomic DNA fragments size fractionated by gel electrophoresis

A modified procedure for preparing cosmid libraries from genomic DNA is described. Genomic DNA was partially digested with a restriction endonuclease, and DNA fragments of appropriate size fractionated by agarose gel electrophoresis. A cosmid library was prepared, prescreened, and used to isolate gene inserts with previously published procedures. In one series of experiments, a modified cosmid vector containing stuffer fragments was used to prepare cosmid libraries containing partial SphI digests of 25 to 35 kb. From 10(5) to 10(7) clones were obtained per microgram of size-fractionated genomic DNA. From 10 to 100 hybridization-positive clones of a single copy gene (COL2A1) were obtained from plates that were positive in the prescreening step. Restriction mapping of over 20 clones and nucleotide sequencing of over 20,000 bp in each of two clones indicated that the inserts were faithful copies of the gene. In another experiment, a standard cosmid vector was used to prepare a cosmid library containing partial BamHI fragments of 30 to 45 kb. Genomic libraries can be prepared with 5 to 20 micrograms of genomic DNA and a large number of clones containing 25 to 45 kb fragments of a single copy gene can be isolated in about three weeks.

The human type II procollagen gene: identification of an additional protein-coding domain and location of potential regulatory sequences in the promoter and first intron

The complete DNA sequence (6 kb) of the 5' portion of the human type II procollagen gene (COL2A1) was determined from the promoter through the third exon including intron sequences and 690 bp of 5' flanking sequence. Three regions between -501 and -649 in the human promoter share high sequence homology to the rat type II procollagen gene and suggest that the functional sequences within the promoter may extend to at least 649 bp upstream from the start site of transcription. The first intron of the human gene contains elements known to play a role in transcription of other genes: three GC boxes, an inverted repeat with homology to a serum responsive element, a viral core enhancer motif, a high-affinity recognition sequence for nuclear factor-1, and an alternating purine/pyrimidine stretch composed of GT repeats. Both the promoter and a portion of the first intron have a high percentage of G + C residues and a high frequency of CpG dinucleotides. In addition, a protein domain that has been identified in the human COL2A1 gene is present in pro-alpha 1(I) and pro-alpha 1(III) collagen but was not previously described for pro-alpha 1(II) collagen. On the basis of this new information we present a modified gene structure for the exons encoding the pro-alpha 1(II) collagen NH2-propeptide.

Characterization of a fibrillar collagen gene in sponges reveals the early evolutionary appearance of two collagen gene families

We have characterized cDNA and genomic clones coding for a sponge collagen. The partial cDNA has an open reading frame encoding 547 amino acid residues. The conceptual translation product contains a probably incomplete triple-helical domain (307 amino acids) with one Gly-Xaa-Yaa-Zaa imperfection in the otherwise perfect Gly-Xaa-Yaa repeats and a carboxyl propeptide (240 amino acids) that includes 7 cysteine residues. Amino acid sequence comparisons indicate that this sponge collagen is homologous to vertebrate and sea urchin fibrillar collagens. Partial characterization of the corresponding gene reveals an intron-exon organization clearly related to the fibrillar collagen gene family. The exons coding for the triple-helical domain are 54 base pairs (bp) or multiples thereof, except for a 57-bp exon containing the Gly-Xaa-Yaa-Zaa coding sequence and for two unusual exons of 126 and 18 bp, respectively. This latter 18-bp exon marks the end of the triple-helical domain, contrary to the other known fibrillar collagen genes that contain exons coding for the junction between the triple-helical domain and the carboxyl propeptide. Compared to other fibrillar collagen genes, the introns are remarkably small. Hybridization to blotted RNAs established that the gene transcript is 4.9 kilobases. Together with previous results that showed the existence of a nonfibrillar collagen in the same species, these data demonstrate that at least two collagen gene families are represented in the most primitive metazoa.

Single base mutation in the type II procollagen gene (COL2A1) as a cause of primary osteoarthritis associated with a mild chondrodysplasia

A cosmid clone was isolated that contained an allele for the type II procollagen gene previously shown to be coinherited with primary generalized osteoarthritis in a large family. Affected members of the family had evidence of a mild chondrodysplasia, but they developed progressive osteoarthritic changes in many joints that had no epiphyseal deformities. The clone contained 52 of the 54 exons of the gene. Nucleotide sequencing of greater than 20,000 base pairs from the clone demonstrated that all the coding sequences and all the intron-exon boundaries were normal except for a single base mutation that converted the codon for arginine at position 519 of the alpha 1(II) chain to a codon for cysteine, an amino acid not found in type II collagen from humans or a variety of other species. The mutation was found in all affected members of the family but not in unaffected members or in 57 unrelated individuals.

Constitutional and somatic deletions of two different regions of maternal chromosome 11 in Wilms tumor

Loss of heterozygosity for 11p markers and preferential loss of maternal alleles have been described in Wilms tumor. In this report we describe the molecular characterization of the constitutional and somatic 11p rearrangements in a del(11p13) WAGR patient with Wilms tumor. Both rearrangements led to loss of maternal alleles for two different regions of 11p, namely, 11p13 and 11p14----p15. This result clearly suggests that Knudson's hypothesis of two hits at the same locus does not necessarily apply to Wilms tumor. Moreover, the loss of 11p15 maternal alleles in the tumor is not incompatible with maternal inheritance of predisposition at 11p13. The putative roles of these two loci are discussed.

Tandem duplication within a type II collagen gene (COL2A1) exon in an individual with spondyloepiphyseal dysplasia

We have characterized a mutation in the type II collagen gene (COL2A1) that produces a form of spondyloepiphyseal dysplasia. The mutation is an internal tandem duplication of 45 base pairs within exon 48 and results in the addition of 15 amino acids to the triple-helical domain of the alpha 1 chains of type II collagen derived from the abnormal allele. Although the repeating (Gly-Xaa-Yaa)n motif that characterizes the triple-helical domain is preserved, type II collagen derived from cartilage of the affected individual contains a population with excessive posttranslational modification, consistent with a disruption in triple-helix structure. The mutation is not carried by either parent, indicating that the phenotype in the affected individual is due to a new dominant mutation. DNA sequence homology in the area of the duplication suggests that the mutation may have arisen by unequal crossover between related sequences, a proposed mechanism in the evolution and diversification of the collagen gene family.

Exclusion of COL2A1 as a candidate gene in a family with Wagner-Stickler syndrome

A large family with Wagner's vitreoretinal degeneration but none of the non-ocular features of Stickler's syndrome has been studied with gene probes for type II collagen. Recombination has been observed, thus excluding type II collagen as the site of mutation in this family. This report supports other published evidence that the Wagner-Stickler syndrome is genetically heterogeneous.

Genetic linkage analysis of hereditary arthro-ophthalmopathy (Stickler syndrome) and the type II procollagen gene

Hereditary arthro-ophthalmopathy (AO), or Stickler syndrome, is a dominantly inherited disorder characterized by vitreo-retinal degeneration and frequently accompanied by epiphyseal dysplasia and premature degenerative joint disease. Three large families with AO were analyzed for clinical manifestations of the disease and for coinheritance of the genetic defect with RFLPs in the type II procollagen gene (COL2A1). Genetic linkage between AO and COL2A1 was demonstrated in the largest family, with a maximum LOD score of 3.52 at a recombination distance of zero. Data from a second family also supported linkage of AO and COL2A1, with a LOD score of 1.20 at a recombination distance of zero. These results are consistent with the conclusion that mutations in the COL2A1 gene are responsible for AO in these two families. In a third AO family, however, recombination between AO and COL2A1 occurred in at least one meiosis, and the data were inconclusive with respect to linkage.

Structure of cDNA clones coding for human type II procollagen. The alpha 1(II) chain is more similar to the alpha 1(I) chain than two other alpha chains of fibrillar collagens

Overlapping cDNA clones were isolated for human type II procollagen. Nucleotide sequencing of the clones provided over 2.5 kb of new coding sequences for the human pro alpha 1(II) gene and the first complete amino acid sequence of type II procollagen from any species. Comparison with published data for cDNA clones covering the entire lengths of the human type I and type III procollagens made it possible to compare in detail the coding sequences and primary structures of the three most abundant human fibrillar collagens. The results indicated that the marked preference in the third base codons for glycine, proline and alanine previously seen in other fibrillar collagens was maintained in type II procollagen. The domains of the pro alpha 1(II) chain are about the same size as the same domains of the pro alpha chains of type I and type III procollagens. However, the major triple-helical domain is 15 amino acid residues less than the triple-helical domain of type III procollagen. Comparison of hydropathy profiles indicated that the alpha chain domain of type II procollagen is more similar to the alpha chain domain of the pro alpha 1(I) chain than to the pro alpha 2(I) chain or the pro alpha 1(III) chain. The results therefore suggest that selective pressure in the evolution of the pro alpha 1(II) and pro alpha 1(I) genes is more similar than the selective pressure in the evolution of the pro alpha 2(I) and pro alpha 1(III) genes.

A PvuII polymorphism near the 5' end of the type II procollagen gene [COL2A1]

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Structural analyses of the polymorphic area in type II collagen gene

The structure of type II collagen gene is extremely well conserved but contains a cluster of high frequency polymorphisms in a 2.2 kb area. Here we report the nucleotide sequence of this DNA area, essential for the PCR-facilitated RFLP-analyses of this gene. In the structural analyses we found four differences in the deduced human amino acid sequence when compared to the published bovine amino acid sequence. The donor and acceptor signals and branch point signals required for the splicing events were in agreement with mammalian consensus sequences. The frequency of inverted repeats which could provoke the DNA strand to loop formation and consequently to deletion mutations did not differ from that found in other sequenced genes coding for fibrillar collagens. mutations did not differ from that found in other sequenced genes coding for fibrillar collagens.

Identification of the molecular defect in a family with spondyloepiphyseal dysplasia

Spondyloepiphyseal dysplasias (SED) are a heterogeneous group of inherited disorders characterized by disproportionate short stature and pleiotropic involvement of the skeletal and ocular systems. Evidence has suggested that SED may result from structural defects in type II collagen. To confirm the validity of this hypothesis, the structure of the "candidate" type II collagen gene (COL2A1) has been directly examined in a relatively large SED family. Coarse scanning of the gene by Southern blot hybridization identified an abnormal restriction pattern in one of the affected members of the kindred. Analysis of selected genomic fragments, amplified by the polymerase chain reaction, precisely localized the molecular defect and demonstrated that all affected family members carried the same heterozygous single-exon deletion. As a consequence of the mutation, nearly 90 percent of the assembled type II collagen homotrimers are expected to contain one or more procollagen subunits harboring an interstitial deletion of 36 amino acids in the triple helical domain.