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PubMed1991

Expression of a human cartilage procollagen gene (COL2A1) in mouse 3T3 cells.

Expression in a recombinant system has been difficult to obtain for any of the major fibrillar collagens that require processing by eight or more post-translational enzymes. Here, two DNA constructs were designed so that the promoter region of the gene for the pro-alpha 1(I) chain of human type I procollagen drove expression of the human type II procollagen gene in mouse NIH 3T3 cells, a culture line that normally synthesizes type I procollagen but not any cartilage-specific protein such as type II procollagen. Both constructs were expressed as both mRNA and protein. In clones expressing the construct at high levels, the steady-state levels of mRNA and the production of type II procollagen were comparable to the mRNA levels and production of type I procollagen from the endogenous mouse genes. Comparison of clones containing the two constructs demonstrated that sequences extending 80 base pairs beyond the major polyadenylation signal of the gene are not in themselves sufficient for correct termination and 3' processing of RNA transcripts. The results strongly suggest that specific sequences present in a downstream 3.5-kilobase SphI/SphI fragment determine the termination of the transcription. Of special importance is that the system will make it possible to examine the consequences of mutations in the human type II procollagen gene on the processing of RNA transcripts and on the functional properties of the protein simply by using the genomic DNA from leukocytes or other non-cartilaginous sources.

Animals↗
PubMed1987

A point mutation in a type I procollagen gene converts glycine 748 of the alpha 1 chain to cysteine and destabilizes the triple helix in a lethal variant of osteogenesis imperfecta.

Synthesis of type I procollagen was examined in fibroblasts from a proband with a lethal perinatal variant of osteogenesis imperfecta. After trypsin digestion of the type I procollagen, a portion of the alpha 1 (I) chains was recovered as disulfide-linked dimers. Digestion of the protein with vertebrate collagenase and mapping of cyanogen bromide peptides suggested that a new cysteine residue was present between residues 551 and 775 of the alpha 1 (I) chain. Sequencing of cloned cDNAs prepared using mRNA from the proband's fibroblasts demonstrated that some of the clones contained a single base mutation that converted the glycine codon in amino acid position 748 of the alpha 1 (I) chain to a cysteine codon. About 80% of the type I procollagen synthesized by the proband's fibroblasts had a decreased thermal stability. The results, therefore, were consistent with the conclusion that normal pro-alpha 1 (I) chains and pro-alpha 1 (I) chains containing a cysteine residue in the alpha chain domain were synthesized in about equal amounts and incorporated randomly into type I procollagen. However, only about 10% of the alpha 1 (I) chains generated by trypsin digestion were disulfide-linked. Further studies demonstrated a decreased rate of secretion of type I procollagen containing the new cysteine residue and decreased processing of the protein by procollagen N-proteinase in cultures of postconfluent fibroblasts. Both parents were phenotypically normal and their fibroblasts synthesized only normal type I procollagen. Therefore, the mutation in the proband was a sporadic one and is very likely to have caused the connective tissue fragility that produced the lethal phenotype.

Amino Acid Sequence↗
PubMed1985

Type I procollagen carboxyl-terminal proteinase from chick embryo tendons. Purification and characterization.

Procollagen carboxyl-terminal proteinase, the enzyme which cleaves the carboxyl-terminal propeptides from type I procollagen, was extensively purified in a yield of 25% from pooled culture media of 17-day-old chick embryo tendons using a procedure which involved chromatography on Green A Dye matrix gel, concanavalin A-Sepharose and heparin-Sepharose, and filtration gels of Sephacryl S-300 and S-200. The purified enzyme is a neutral, Ca2+-dependent proteinase which is inhibited by metal chelators, but not by inhibitors for serine and cysteine proteinases. Calcium in a concentration of 5-10 mM is required for optimal activity. The molecular weight of the enzyme was determined to be 97,000-110,000 by gel filtration and by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. Other properties of the carboxyl-terminal proteinase are: 1) the Km for the type I procollagen is 96 nM at pH 7.5 and 35 degrees C; 2) the activation energy for the reaction with type I procollagen is 21,000 cal mol-1; 3) amino acid sequencing of the released carboxyl-terminal propeptide indicated the enzyme specifically cleaves an -Ala-Asp- bond in both the pro-alpha 1(I) and pro-alpha 2(I) chains; 4) the enzyme specifically cleaves the carboxyl-terminal propeptides of a homotrimer of pro-alpha 1(I) chains and type II and III procollagens, but it does not cleave type IV procollagen. The results suggest that the enzyme is involved in the processing of type I procollagen in vivo.

Amino Acid Sequence↗
PubMed1979

Characterization of a type IV procollagen synthesized by human amniotic fluid cells in culture.

Fetal epithelioid cells, isolated from human amniotic fluid, synthesize and secrete a type IV-like procollagen characterized by a unique pattern of cyanogen bromide (CNBr)-produced peptides. The procollagen is disulfide-bonded and, after reduction, migrates on sodium dodecyl sulfate-polyacrylamide gel electrophoresis as a doublet between collagen beta components and pro-alpha 1(I) chains. No conversion of the procollagen to collagen or to procollagen intermediates is observed in cell culture. The procollagen was purified by salt fractionation and ion exchange chromatography; its amino acid composition resembles that of collagenous proteins extracted from basement membranes, with a high 3- and 4-hydroxyproline and hydroxylysine content and low levels of alanine and arginine. The major products obtained after limited proteolytic digestion of the protein retain interchain disulfide bonds and, after reduction, migrate on sodium dodecyl sulfate-polyacrylamide gel electrophoresis near intact pro-alpha 1(I) chains. The procollagen is secreted efficiently by amniotic fluid cells despite almost complete inhibition of peptidyl hydroxylation but, unlike type I procollagen, the secreted underhydroxylated chains lack interchain disulfide bonds. Since these cells also secrete fibronectin and elaborate an extensive extracellular matrix, the system should prove useful in the study of cell-matrix interactions.

Amino Acids↗
PubMed1981

Chain assembly intermediate in the biosynthesis of type III procollagen in chick embryo blood vessels.

A general mechanism for the assembly of procollagens is proposed from a biosynthetic study of procollagen III. This was shown to proceed by a stepwise process punctuated by disulfide bond formation and an assembly intermediate was recovered. The biosynthesis of type III procollagen in excised chick embryo blood vessels was studied by radioactive labeling for 30 min. Velocity sedimentation under denaturing conditions and purified antibodies specific against bovine amino propeptide III were used to identify and characterize monomeric pro alpha 1 III chains and a type III procollagen intermediate which is interchain disulfide-linked only at the carboxyl end but not at the amino end. The monomeric chains presumably have intrachain disulfide bonds within the propeptides. The monomeric pro alpha 1 III chains were also found when alpha, alpha'-dipyridyl was present during incubation. Pulse-chase experiments show that the monomeric chains and the intermediate are biosynthetic precursors of type III procollagen. Furthermore, it is shown that monomeric pro alpha 1 chains are not triple helical when extracted under nondenaturing conditions. The results indicate that the assembly of pro alpha 1 III chains into type III procollagen starts with the association of the folded carboxyl propeptides and is followed by formation of disulfide bonds between carboxyl propeptides, folding of the triple helix, and formation of disulfide bonds between amino propeptides. All procollagens may follow a similar assembly sequence.

Animals↗
PubMed1983

Identification of genomic DNA coding for chicken type II procollagen.

A segment of the type II procollagen gene has been isolated by screening a lambda Charon 4A library containing fragments of chicken genomic DNA. The specific clone, LgCOL(II), was selected by hybridization using overlapping inserts from two cDNA clones which are specific for a cartilage procollagen (Vuorio, E., Sandell, L., Kravis, D., Sheffield, V. C., Vuorio, T., Dorfman, A., and Upholt, W. B. (1982) Nucleic Acids Res. 10, 1175-1192). DNA sequence analysis of LgCOL(II) in the COOH-telopeptide region of the protein, shows conclusively that this DNA corresponds to the chicken type II procollagen gene. Hybridization of cDNA probes to restriction fragment gel blots together with DNA sequence analysis have established the orientation and position of the procollagen gene within the lambda Charon 4A vector and indicate that LgCOL(II) contains approximately 6 kilobase pairs of the type II procollagen gene plus additional DNA flanking the 3' end of the gene. DNA sequence analysis shows directly that LgCOL(II) contains DNA sequences identical with those in the cDNA clones. The portion of the gene from amino acid 578 of the triple helical region to the COOH-terminal end of the protein (approximately 700 amino acids) is contained within the clone, corresponding to approximately 50% of the amino acid coding sequence of the gene. This region of the chicken alpha 1 (type II) procollagen gene is encoded within a shorter segment of the chicken genome than is the corresponding region of the alpha 2(type I) procollagen gene.

Amino Acid Sequence↗
PubMed1984

Structure and sequence of the chicken type II procollagen gene. Characterization of the region encoding the carboxyl-terminal telopeptide and propeptide.

The DNA sequence of two overlapping cDNA clones and a genomic lambda clone covering the region coding for 288 amino acids at the COOH terminus of the chicken type II procollagen gene is reported. This region consists of 4 exons coding for the last 15 amino acids of the triple helical domain and 273 amino acids which correspond to the COOH-terminal telopeptide and COOH-terminal propeptide. The sequence, base composition, and codon usage of this region of the type II procollagen gene show particularly high similarity to those of the chicken alpha 1(I) procollagen gene and differ from those of the alpha 2(I) and alpha 1(III) gene sequences. Two DNA tracts of low sequence similarity were observed. One of these regions spans the telopeptide and COOH-terminal propeptidase cleavage site, although 4-5 amino acids at the actual cleavage site are conserved compared with the alpha 1(I) and alpha 2(I) genes. A region of unusually high nucleotide sequence conservation is present in exon 2 (amino acids 171c - 186c ) consisting of approximately 45 nucleotides with only one or two base substitutions compared with the other procollagen genes. Within this conserved sequence is a site for carbohydrate attachment. The 3' nontranslated sequence of the type II procollagen mRNA is longer than that of either the alpha 1(I) or alpha 2(I) mRNA and contains several unusual long tracts consisting primarily of one or two bases. Although the canonical site for polyadenylation is not present, two related sequences, AACAAA and ATATAAA , are present 32 and 41 bases preceding the end of the major RNA species. The exon/intron structure of the type II procollagen gene is similar to that of other collagen genes which have been described. This DNA sequence provides the first extensive report of the amino acid sequence of chicken type II procollagen.

Amino Acid Sequence↗
PubMed1983

Biliary excretion of procollagen type III peptide in healthy humans and in patients with alcoholic cirrhosis of the liver.

Serum concentrations of procollagen type III peptide are found to be elevated in liver disease and to correlate with fibrosis activity in liver tissue. These elevated serum levels may be due to enhanced synthesis, decreased excretion, or release from deposits of the propeptide in connective tissue. To quantitatively investigate the excretion of procollagen type III peptide, we studied its presence in the bile and urine of 10 healthy controls and 11 patients with alcoholic cirrhosis of the liver. Biliary excretion rates of procollagen propeptide were determined by the duodenal perfusion method. The serum concentrations of procollagen type III peptide were 2.5 +/- 0.5 ng/ml in the healthy controls and 33.6 +/- 6.8 ng/ml in the patients with cirrhosis. Procollagen type III peptide was found in the bile; the healthy controls excreted 0.4 +/- 0.07 nmol/h and the cirrhotics excreted 0.98 +/- 0.27 nmol/h. A fragment of the procollagen propeptide, Col 1, was excreted in urine; the healthy controls excreted 0.25 +/- 0.04 nmol/h, and the cirrhotics excreted 0.11 +/- 0.03 nmol/h. These data demonstrate that the biliary excretion of procollagen type III peptide represents a quantitatively important pathway.

Bile↗
PubMed1983

Glucocorticoids coordinately regulate procollagens type I and type III synthesis.

Antibodies to type I and type III procollagens were raised in rabbits and were made monospecific by chromatography on collagen and procollagen affinity columns. The antibodies were determined to be monospecific by the direct enzyme-linked immunosorbent assay and the enzyme-linked immunosorbent assay inhibition assay. Rats were treated with various doses of triamcinolone diacetate, pulse-labeled with radioactive proline for 20 min, and the procollagens were precipitated with procollagen antibodies. The degree of inhibition of procollagen type I and type III synthesis to corticosteroid treatment was the same. This coordinate effect of glucocorticoids on the synthesis of the two procollagens was reversible, dose-dependent, time-dependent, and observed in lung as well as in skin. These data indicate that glucocorticoids coordinately regulate the synthesis of type I and type III procollagen in skin and lung to the same extent.

Animals↗
PubMed1982

Mouse procollagen IV. Characterization and supramolecular association.

The endodermal cell line PF-HR9, derived from the murine teratocarcinoma cell line PCC4-F, was grown as monolayers and as cell clusters called embryoid bodies. Procollagen IV and laminin were isolated from both kinds of culture media. Antibodies specific to collagen IV and to laminin demonstrated these materials in association with the cells and in the culture media. The procollagen IV consisted of pro alpha 1 IV and pro alpha 2 IV chains and gave a circular dichroic spectrum characteristic for collagen helices, with thermal transitions at 40, 44, and 51 degrees C. The molecules were visualized electron microscopically after rotary shadowing. Laminin showed the characteristic beaded cross-appearance, and procollagen IV was a 434 +/- 12-nm long linear thread containing a 17-nm carboxyl-terminal knob. The 7% of collagen helix with Tm = 51 degrees C corresponds to about a 30-nm length of the molecule and is probably that section of the amino end through which several procollagen IV molecules form a junctional complex. Several noncovalent associations of procollagen IV molecules were demonstrated by velocity sedimentation and electron microscopy of concentrated culture media, specifically associations of two and four procollagen IV molecules through their amino ends and dimers linked at their carboxyl ends. The results show that procollagen IV molecules associate noncovalently into the components which others have isolated from basement membranes and strongly support a network model of these supramolecular assemblies.

Animals↗
PubMed1996

Expression of mRNAs for type I and type III procollagens in serous ovarian cystadenomas and cystadenocarcinomas.

Malignant ovarian tumors induce a strong fibro-proliferative reaction characterized by the active production of type I and type III procollagen both locally in the ovary as well as more remotely in the peritoneal cavity. Our purpose was to determine the origin of the increased collagen production observed in serous ovarian tumors with different histological grades of malignancy, ie, whether the malignant cells or the stromal fibroblasts are responsible for the synthesis of collagen fibers. We visualized the mRNAs corresponding to the pro alpha 1(I) and pro alpha 2(I) chains of type I procollagen and the pro alpha 1(III) chain of type III procollagen by in situ hybridization. Strong signals for both chains of type I procollagen were seen in stromal fibroblasts next to tumor cell islets, whereas the reaction was weak or absent near benign ovarian cysts. In poorly differentiated tumors, the signals were particularly abundant and occasionally also seen in the neoplastic cells themselves. Type III procollagen mRNA expression was similar, although somewhat less distinct. These findings indicate that the production of interstitial procollagens is related to the degree of malignancy and neoplastic activity of tumors. The formation of collagen in well differentiated ovarian tumors is a function of stromal fibroblasts, whereas in poorly differentiated tumors, aberrant expression of one or several chains of type I and type III procollagens in the neoplastic cells is also likely to take place.

Antisense Elements (Genetics)↗
PubMed1996

Procollagen gene expression is down-regulated by taurine and niacin at the transcriptional level in the bleomycin hamster model of lung fibrosis.

Taurine (T) and niacin (N) have previously been found to block the accumulation of collagen in the bleomycin (BL) model of interstitial pulmonary fibrosis. The present study was designed to evaluate whether the mechanism for the antifibrotic effect of combined treatment with taurine and niacin involves the down-regulation of BL-induced overexpression of procollagen I and III messenger ribonucleic acid (mRNA) levels in lungs. Hamsters were intratracheally instilled with three consecutive doses of saline or BL at weekly intervals (2.5, 2.0, 1.5 units/5 ml/kg). Four groups of animals were fed a diet throughout the experiment containing either 2.5% taurine and 2.5% niacin or the same diet without the drugs. The four groups were saline-instilled with the control diet (SA + CD), saline-instilled with TN in the diet (SA + TN), BL-instilled with the control diet (BL + CD), and BL-instilled with the TN diet (BL + TN). Steady state transcript levels in total RNA prepared from lungs of all four groups were determined at 0, 3, 7, 14 and 21 days after the last BL instillation by slot blot and Northern blot analyses. Results indicate that procollagen I mRNA levels are elevated compared with saline control by 2.5-, 2.4- and 2.0-fold at 7, 14, and 21 days after the last dose of BL instillation, respectively. Dietary treatment with taurine and niacin decreased the steady state level of BL-induced increases of procollagen I mRNA from day 0 through 21. We observed a similar pattern of procollagen III inhibition by taurine and niacin from day 3 through day 21. Transcription of procollagen I and III genes was readily detected in nuclei prepared from BL-treated lung samples at 14 days after treatment. In contrast, transcription of procollagen I and III genes was barely detectable in nuclei prepared at the same time point from BL + TN treated lungs. Our results suggest that procollagen I and III gene expression in BL-induced lung fibrosis in hamsters is transcriptionally down-regulated by combined treatment with taurine and niacin.

Animals↗
PubMed1997

Altered procollagen mRNA expression during the progression of avian scleroderma.

BACKGROUND: Spontaneous animal models of human autoimmune diseases provide the means to study the very first pathogenetic events, which is not possible in their human counterparts. This is particularly true for connective tissue diseases in which clinical symptoms become manifest only after a long and still obscure course of immunologic, inflammatory, and fibrotic processes. University of California at Davis line 200 chickens (UCD-200) develop a hereditary scleroderma-like disease resembling the entire spectrum of human systemic sclerosis, such as early endothelial cell damage, severe lymphocytic infiltration, and accumulation of collagen in skin and internal organs. MATERIALS AND METHODS: In the present study, we investigated mRNA levels of alpha 1(I), alpha 2(I), alpha 1(II), alpha 1(III), alpha 1(VI), alpha 2(VI), and alpha 3(VI) procollagen and GAPDH using digoxigenin-labeled antisense probes in a nonradioactive ribonuclease protection assay (RPA). We analyzed tissue samples from comb, esophagus, heart, lung, and liver of UCD-200 chickens at different stages of the disease, and healthy UCD-058 chickens. RESULTS: During the early inflammatory stage of the disease, the ratios of procollagen types VI/I and types VI/III increased 7-fold in comb tissue, followed by a 3-fold elevation in type I procollagen transcripts in the late acute stage. In the chronic stage, alpha 1(III) procollagen message was increased 2-fold. Additionally, hybridization with the 180 bp alpha 2(I) antisense probe resulted in two bands of 180 bp and 115 bp, respectively, in the RPA. The ratio of these two previously undescribed bands changes in the early stage of the disease both in comb and esophagus. CONCLUSIONS: In an animal model with a spontaneous scleroderma-like disease we found a characteristic, sequential increase in type VI, type I, and type III procollagen transcripts, and we found evidence for the presence and altered ratio of two mRNA variants of alpha 2(I) procollagen, possibly caused by alternative splicing. Comparative analysis of alpha 2(I) procollagen variants in early stages of avian scleroderma and human SSc might provide answers to unresolved questions concerning the molecular basis for generalized fibrosis in scleroderma.

Acute Disease↗
PubMed1998

Type I procollagen synthesis is regulated by steroids and related hormones in human osteosarcoma cells.

Change in the synthesis of type I collagen, the major extracellular matrix component of skin and bone, are associated with normal growth, tissue repair processes, and several pathological conditions. Expression of the COL 1A1 gene is regulated by transcriptional and post-transcriptional mechanisms. However, the hormonal regulation of type I collagen synthesis in human bone has not been well characterized. We have studied the influence of calcitriol, dexamethasone, retinoic acid, and estradiol on the COL 1A1 gene expression by determining the secretion of the C-terminal propeptide (PICP) and the levels of alpha 1(I) procollagen mRNA in cultured human MG-63 and SaOs-2 osteoblast-like osteosarcoma cells. Similar experiments were also performed with respect to expression of the nuclear proto-oncogenes, c-fos and c-jun, in MG-63 cells. In MG-63 cells, calcitriol stimulated the synthesis and secretion of PICP. The alpha 1(I) procollagen mRNA level was elevated with no effect on message stability, indicating a transcriptional mechanism of regulation. In contrast, dexamethasone treatment was accompanied by an accelerated rate of alpha 1(I) procollagen mRNA turnover, observed as decreased amounts of the message and the secreted PICP, implying a posttranscriptional regulation. Retinoic acid, in turn, decreased the levels of alpha 1(I) procollagen mRNA and secreted PICP by slowing down transcription of the COL1A1 gene without any effect on message stability. The ability of these hormones to regulate the alpha 1(I) transcripts was sensitive to puromycin treatment, suggesting an involvement of an induced mediator protein in the action of the hormones on the COL1A1 gene. Both dexamethasone and calcitriol rapidly but transiently increased the expression of the c-fos and c-jun proto-oncogenes. Neither proto-oncogene responded to retinoic acid treatment with significant changes in mRNA levels. Estradiol treatment was found to have no influence on type I procollagen synthesis. In SaOs-2 cells, which are not as well differentiated as the MG-63 cells, calcitriol and dexamethasone did not influence type I procollagen synthesis. Retinoic acid as well as estradiol reduced collagen gene expression in these cells. These findings suggest that hormonal effects on type I procollagen synthesis may depend on the maturational state of the osteoblastic cells that express different regulatory factors and receptors, resulting in, in each case, a finely adjusted rate of gene expression.

Administration, Topical↗
PubMed2005

Identifying the SPARC binding sites on collagen I and procollagen I by atomic force microscopy.

SPARC (secreted protein acidic and rich in cysteine) is a matricellular protein associated with the extracellular matrix (ECM). It has been found that the production of collagen I is a requisite for the association of SPARC with ECM, and studies with SPARC-null mice indicate that SPARC plays a role in modifying the structure of collagen fibers. It is not known, however, whether SPARC interacts with the collagen I precursor, procollagen I. In this study, the binding of SPARC to collagen I and procollagen I was verified by surface plasmon resonance. The SPARC-binding sites on collagen I and procollagen I were identified by directly visualizing their complexes using tapping-mode atomic force microscopy (TM-AFM). The characteristic chain end feature in collagen I is not readily detected by AFM, so unambiguous location of the binding sites relative to the C- or N-termini is difficult. In contrast, procollagen I, with its large globular C-propeptide, permits easy identification of the C-terminus. Histograms were constructed and compared based on the distances of the bound SPARC to the C-terminus of procollagen I and to the closest end of collagen I. There is a broad distribution of SPARC binding sites on procollagen I with the most preferred binding region located approximately 1/3 from the C-terminus. Characterization of the SPARC-binding sites on collagen I and procollagen I provides useful information for further understanding of the functional implications of their interactions.

Animals↗
PubMed2002

Impaired balance of type I and type III procollagen mRNA in cultured fibroblasts of patients with incisional hernia.

BACKGROUND: Recent findings of an impaired protein ratio of type I to type III procollagen showed a disturbed collagen metabolism in incisional hernia development. We analyzed the type I and type III procollagen messenger RNA to investigate whether these findings represent the altered extracellular matrix or a primary defect at the transcriptional level. METHODS: We examined cultured skin fibroblasts of patients with incisional or recurrent incisional hernia in comparison with those without any previous incision (control) and those with a skin scar without clinical appearance of a hernia (scar). Immunohistochemical detection of a lowered protein ratio of type I and type III collagen in the hernia skin tissue leads to mRNA expression analysis. The procollagen mRNA and the ratio of type I to type III procollagen mRNA are detected by reverse transcriptase-polymerase chain reaction and Northern blot analysis, the collagens type I and III by Western blot analysis. RESULTS: Reverse transcriptase-polymerase chain reaction revealed an increase of type I procollagen mRNA in the incisional and recurrent hernia (0.90 +/- 0.04 and 1.19 +/- 0.04, respectively) compared with stable scar (0.54 +/- 0.02) or healthy tissue (0.43 +/- 0.01). The obvious rise of type III procollagen mRNA to 4.13 +/- 0.04 for incisional, 6.02 +/- 0.03 for recurrent hernia, 2.29 +/- 0.04 for stable scar, and 1.72 +/- 0.03 for the healthy tissue showed a significantly decreased ratio of type I to type III procollagen mRNA in the hernia patients as compared with the controls (P <.01). By Western blot analysis, an increase of type I and type III collagen protein and a significant rise in the corresponding ratio in the recurrent hernia group were detected. CONCLUSIONS: The altered synthesis of type I and type III collagen in cultured skin fibroblasts suggests a disorder of collagen metabolism, at least in patients with recurrent hernia. Hence, a basically impaired wound healing process is likely to contribute to the unsatisfactory results of incisional hernia repair.

Blotting, Western↗
PubMed2005

Identification of the minimal domain structure of bone morphogenetic protein-1 (BMP-1) for chordinase activity: chordinase activity is not enhanced by procollagen C-proteinase enhancer-1 (PCPE-1).

Bone morphogenetic protein 1 (BMP-1), which is a tolloid member of the astacin-like family of zinc metalloproteinases, is a highly effective procollagen C-proteinase (PCP) and chordinase. On the other hand, mammalian tolloid like-2 (mTLL-2) does not cleave chordin or procollagen; procollagen is cleaved by mTLL-2 in the presence of high levels of procollagen C-proteinase enhancer-1 (PCPE-1), for reasons that are unknown. We used these differences in activity between BMP-1 and mTLL-2 to narrow in on the domains in BMP-1 that specify PCP and chordinase activity. Using a domain swap approach, we showed that: 1) the metalloproteinase and CUB2 domains of BMP-1 are absolutely required for PCP activity; swaps with either of the corresponding domains in BMP-1 and mTLL-2 did not result in procollagen cleavage and 2) the proteinase domain of mTLL-2 can cleave chordin if coupled to the CUB1 domain of BMP-1. Therefore, the minimal structure for chordinase activity comprises a metalloproteinase domain (either from BMP-1 or from mTLL-2) and the CUB1 domain of BMP-1 (the CUB1 domain of mTLL-2 cannot substitute for the CUB1 domain of BMP-1). We showed that the minimal procollagen C-proteinase (BMP-1 lacking the EGF and CUB3 domain) was enhanced by PCPE-1 but not as well as BMP-1 retaining the CUB3 domain. Further studies showed that PCPE-1 had no effect on the ability of BMP-1 to cleave chordin. The data support a previously suggested mechanism of PCPE-1 whereby PCPE-1 interacts with procollagen, but in addition, the CUB3 domain of BMP-1 appears to augment the interaction.

Blotting, Western↗
PubMed2005

Expression of Col1a1, Col1a2 and procollagen I in germ cells of immature and adult mouse testis.

The objective of this study was to compare the expression of Col1a1, Col1a2, and procollagen I in the seminiferous tubules of immature and adult mice and to characterize the cellular expression pattern of procollagen I in germ cells during spermatogenesis in order to provide necessary groundwork for further functional studies in the process of spermatogenesis. Microarray analysis demonstrated that Col1a1 and Col1a2 were abundantly expressed in the seminiferous tubules of 6-day-old mice compared with 60-day-old mice, and the expression levels of Col1a1 and Col1a2 mRNA were validated using a semi-quantitative RT-PCR assay. Western blot analysis further confirmed that procollagen I was expressed at a higher level in the seminiferous tubules of 6-day-old mice compared with 60-day-old mice. Immunohistochemical analysis revealed that type A spermatogonia were positive for procollagen I in the testis of 6-day-old mice, whereas Sertoli cells were negative for this protein. The in vivo procollagen I staining in type A spermatogonia was corroborated in spermatogonia exhibiting a high potential for proliferation and the ability to form germ cell colonies in in vitro culture. Moreover, procollagen I was also detected in type A spermatogonia, intermediate spermatogonia, type B spermatogonia, and preleptotene spermatocytes in the adult mouse testes, but positive staining disappeared in more differentiated germ cell lineages detaching from the basement membrane, including leptotene spermatocytes, pachytene spermatocytes, round spermatids and elongated spermatids. These data suggest that Col1a1, Col1a2 and procollagen I are associated with type A spermatogonia and play a potential role in mediating the detachment and migration of germ cells during spermatogenesis.

Animals↗