Biomedical subjects

T Pihlajaniemi

Publications and source records attributed to T Pihlajaniemi.

At least 19 recordsLinked to original sources

PubMed2001

Abnormal adherence junctions in the heart and reduced angiogenesis in transgenic mice overexpressing mutant type XIII collagen.

Type XIII collagen is a type II transmembrane protein found at sites of cell adhesion. Transgenic mouse lines were generated by microinjection of a DNA construct directing the synthesis of truncated alpha1(XIII) chains. Shortened alpha 1(XIII) chains were synthesized by fibroblasts from mutant mice, and the lack of intracellular accumulation in immunofluorescent staining of tissues suggested that the mutant molecules were expressed on the cell surface. Transgene expression led to fetal lethality in offspring from heterozygous mating with two distinct phenotypes. The early phenotype fetuses were aborted by day 10.5 of development due to a lack of fusion of the chorionic and allantoic membranes. The late phenotype fetuses were aborted by day 13.5 of development and displayed a weak heartbeat, defects of the adherence junctions in the heart with detachment of myofilaments and abnormal staining for the adherence junction component cadherin. Decreased microvessel formation was observed in certain regions of the fetus and the placenta. These results indicate that type XIII collagen has an important role in certain adhesive interactions that are necessary for normal development.

Adherens Junctions↗

PubMed2001

Endostatin-induced modulation of plasminogen activation with concomitant loss of focal adhesions and actin stress fibers in cultured human endothelial cells.

Endostatin, a M(r) 20,000 fragment of collagen XVIII, is able to inhibit angiogenesis and induce apoptosis in endothelial cells in vivo. We analyzed the effectsof recombinant endostatin on human microvascular endothelial cells, focusing on pericellular plasminogen activation and its targeting by the focal adhesion-associated cytoskeletal structures. Analysis of the proteolytic plasminogen activator system revealed that endostatin modulates the distribution of soluble and cell surface-associated urokinase-type plasminogen activator (uPA) and plasminogen activator inhibitor, type 1 (PAI-1). Casein zymographic and immunoprecipitation analyses indicated that endostatin exerts its effects by decreasing the levels of soluble uPA and PAI-1 and their complexes in a dose-dependent manner. Immunofluorescence analysis of cell surface-associated uPA indicated that endostatin treatment caused the redistribution of receptor-bound uPA from focal contacts, resulting in diffuse cell surface staining. In accordance with this observation, immunofluorescence staining of the urokinase receptor revealed that endostatin treatment removed uPAR from focal adhesions. Accordingly, endostatin caused a rapid disassembly of focal adhesions as observed by immunofluorescence analysis of the focal adhesion proteins vinculin and paxillin. A prominent change in the cytoskeletal architecture was observed as the actin stress fiber network was dissociated in response to endostatin treatment. The effect of focal adhesion disassembly was reversible, persisting from 1 h up to 6 h. Our results suggest that the antiangiogenic activity of endostatin involves the modulation of focal adhesions and actin stress fibers and the down-regulation of the urokinase plasminogen activator system.

Actins↗

PubMed2001

The NC1/endostatin domain of Caenorhabditis elegans type XVIII collagen affects cell migration and axon guidance.

Type XVIII collagen is a homotrimeric basement membrane molecule of unknown function, whose COOH-terminal NC1 domain contains endostatin (ES), a potent antiangiogenic agent. The Caenorhabditis elegans collagen XVIII homologue, cle-1, encodes three developmentally regulated protein isoforms expressed predominantly in neurons. The CLE-1 protein is found in low amounts in all basement membranes but accumulates at high levels in the nervous system. Deletion of the cle-1 NC1 domain results in viable fertile animals that display multiple cell migration and axon guidance defects. Particular defects can be rescued by ectopic expression of the NC1 domain, which is shown to be capable of forming trimers. In contrast, expression of monomeric ES does not rescue but dominantly causes cell and axon migration defects that phenocopy the NC1 deletion, suggesting that ES inhibits the promigratory activity of the NC1 domain. These results indicate that the cle-1 NC1/ES domain regulates cell and axon migrations in C. elegans.

Amino Acid Sequence↗

PubMed2001

Interaction of endostatin with integrins implicated in angiogenesis.

Endostatin, a fragment of collagen XVIII, is a potent antagonist of angiogenesis and inhibitor of tumor growth in mouse models. At present, the mechanism of action of endostatin is unknown. We show here that recombinantly produced human endostatin interacts with alpha(5)- and alpha(v)-integrins on the surface of human endothelial cells. We further demonstrate that the endostatin-integrin interaction is of functional significance in vitro, as we found that immobilized endostatin supports endothelial cell survival and migration in an integrin-dependent manner. Soluble endostatin in turn inhibits integrin-dependent endothelial cell functions, such as cell migration. Taken together, these results implicate integrins as potential targets for endostatin function and support the importance of integrins in endothelial cell biology and angiogenesis.

Angiogenesis Inhibitors↗

PubMed2001

Lack of type XV collagen causes a skeletal myopathy and cardiovascular defects in mice.

Type XV collagen occurs widely in the basement membrane zones of tissues, but its function is unknown. To understand the biological role of this protein, a null mutation in the Col15a1 gene was introduced into the germ line of mice. Despite the complete lack of type XV collagen, the mutant mice developed and reproduced normally, and they were indistinguishable from their wild-type littermates. However, Col15a1-deficient mice showed progressive histological changes characteristic for muscular diseases after 3 months of age, and they were more vulnerable than controls to exercise-induced muscle injury. Despite the antiangiogenic role of type XV collagen-derived endostatin, the development of the vasculature appeared normal in the null mice. Nevertheless, ultrastructural analyses revealed collapsed capillaries and endothelial cell degeneration in the heart and skeletal muscle. Furthermore, perfused hearts showed a diminished inotropic response, and exercise resulted in cardiac injury, changes that mimic early or mild heart disease. Thus, type XV collagen appears to function as a structural component needed to stabilize skeletal muscle cells and microvessels.

Animals↗

PubMed2001

Tumor progression is associated with a significant decrease in the expression of the endostatin precursor collagen XVIII in human hepatocellular carcinomas.

Endostatin inhibits angiogenesis and tumor growth in mice. The role of its endogenous precursor collagen XVIII in human cancer is unknown. In normal tissues, two variants of collagen XVIII, namely, the short and long forms regulate tissue specificity, the long form being almost exclusively expressed by hepatocytes in the liver. We analyzed RNA arrays from 57 hepatocellular carcinomas (HCCs) with common and variant-specific probes and investigated the relationships between collagen XVIII expression and angiogenesis by measuring the CD34-positive microvessel density. Low collagen XVIII expression by tumor hepatocytes was associated with large tumor size (r, -0.63; P < 0.001) and replacement of trabeculae with pseudoglandular-solid architecture (chi2, 28; P < 0.001), which indicate tumor progression. Tumors expressing the highest collagen XVIII levels were smaller and had lower microvessel density (P = 0.01) than those expressing moderate levels; and HCCs with the lowest collagen XVIII levels approached a plateau of microvessel density, which indicated that a decrease in collagen XVIII expression is associated with angiogenesis in primary liver cancer. HCCs recurring within 2 years of resection showed 2.2-fold lower collagen XVIII mRNA than nonrecurring ones (P = 0.02). The findings relied on the hepatocyte-specific long form. Thus, the endogenous expression of the endostatin precursor decreases along with tumor progression in HCCs.

Alternative Splicing↗

PubMed2001

Physical mapping of mouse collagen genes on chromosome 10 by high-resolution FISH.

Fluorescence in situ hybridization (FISH) on mechanically stretched chromosomes (MSCs) and extended DNA fibers enables construction of high-resolution physical maps by accurate ordering and orienting genomic clones as well as by measuring physical lengths of gaps and overlaps between them. These high-resolution FISH targets have hitherto been used mainly in the study of the human genome. Here we have applied both MSCs and extended DNA fibers to the physical mapping of the mouse genome. At first, five mouse collagen genes were localized by metaphase-FISH: Col10a1 to chromosomal bands 10B1-B3; Col13a1 to 10B4; and Col6a1, Col6a2, and Col18a1 to 10B5-C1. The mutual order of the genes, centromere--Col10a1--Col13a1--Col6a2--Col6a1--Col18a1--telomere, was determined by FISH on metaphase chromosomes, MSCs, and extended DNA fibers. To our knowledge, this is the first time mouse metaphase chromosomes have been stretched and used as targets for FISH. We also used MSCs to determine the transcriptional orientations, telomere--5'-->3'--centromere, of both Col13a1 and Col18a1. With fiber-FISH, Col18a1, Col6a1, and Col6a2 were shown to be in a head-to-tail configuration with respective intergenic distances of about 350 kb and 90 kb. Comparison of our physical mapping results with the homologous human data reveals both similarities and differences concerning the chromosomal distribution, order, transcriptional orientations, and intergenic distances of the collagen genes studied.

Animals↗

PubMed2001

Lack of cytosolic and transmembrane domains of type XIII collagen results in progressive myopathy.

Type XIII collagen is a type II transmembrane protein found at many sites of cell adhesion in tissues. Homologous recombination was used to generate a transgenic mouse line (Col13a1(N/N)) that expresses N-terminally altered type XIII collagen molecules lacking the short cytosolic and transmembrane domains but retaining the large collagenous ectodomain. The mutant molecules were correctly transported to focal adhesions in cultured fibroblasts derived from the Col13a1(N/N) mice, but the cells showed decreased adhesion when plated on type IV collagen. These mice were viable and fertile, and in immunofluorescence stainings the mutant protein was located in adhesive tissue structures in the same manner as normal alpha1(XIII) chains. In immunoelectron microscopy of wild-type mice type XIII collagen was detected at the plasma membrane of skeletal muscle cells whereas in the mutant mice the protein was located in the adjacent extracellular matrix. Affected skeletal muscles showed abnormal myofibers with a fuzzy plasma membrane-basement membrane interphase along the muscle fiber and at the myotendinous junctions, disorganized myofilaments, and streaming of z-disks. The findings were progressive and the phenotype was aggravated by exercise. Thus type XIII collagen seems to participate in the linkage between muscle fiber and basement membrane, a function impaired by lack of the cytosolic and transmembrane domains.

Amino Acid Sequence↗

PubMed2001

Type XIII collagen: a novel cell adhesion component present in a range of cell-matrix adhesions and in the intercalated discs between cardiac muscle cells.

Recent analysis of type XIII collagen surprisingly showed that it is anchored to the plasma membranes of cultured cells via a transmembrane segment near its amino terminus. Here we demonstrate that type XIII collagen is concentrated in cultured skin fibroblasts and several other human mesenchymal cell lines in the focal adhesions at the ends of actin stress fibers, co-localizing with the known focal adhesion components talin and vinculin. This co-occurrence was also observed in rapidly forming adhesive structures of spreading and moving fibroblasts and in disrupting focal adhesions following microinjection of the Rho-inhibitor C3 transferase into the cells, suggesting that type XIII collagen is an integral focal adhesion component. Moreover, it appears to have an adhesion-related function since cell-surface expression of type XIII collagen in cells with weak basic adhesiveness resulted in improved cell adhesion on selected culture substrata. In tissues type XIII collagen was found in a range of integrin-mediated adherens junctions including the myotendinous junctions and costameres of skeletal muscle as well as many cell-basement membrane interfaces. Some cell-cell adhesions were found to contain type XIII collagen, most notably the intercalated discs in the heart. Taken together, the results strongly suggest that type XIII collagen has a cell adhesion-associated function in a wide array of cell-matrix junctions.

Animals↗

PubMed2001

Distinct expression of type XIII collagen in neuronal structures and other tissues during mouse development.

Type XIII collagen is a type II transmembrane protein found in adhesive structures of mature tissues. We describe here its expression and spatio-temporal localization during mouse fetal development. Type XIII collagen mRNAs were expressed at a constant rate during development, with an increase of expression towards birth. Strong type XIII collagen expression was detected in the central and peripheral nervous systems of the developing mouse fetus in mid-gestation. Cultured primary neurons also expressed this collagen, and it was found to enhance neurite outgrowth. The results suggest that type XIII collagen is a new member among the proteins involved in nervous system development. Strong expression during early development was also detected in the heart, with localization to cell-cell contacts and accentuation in the intercalated discs perinatally. During late fetal development, type XIII collagen was observed in many tissues, including cartilage, bone, skeletal muscle, lung, intestine and skin. Clear developmental shifts in expression suggest a role in endochondral ossification of bone and the branching morphogenesis in the lung. Notable structures lacking type XIII collagen were the endothelia of most blood vessels and the endocardium. Its initially unique staining pattern began to concentrate in the same adhesive structures where it exists in adult tissues, and started to resemble that of the beta1 integrin subunit and vinculin during late intrauterine development and in the perinatal period.

Animals↗

PubMed2001

Tumor hepatocytes and basement membrane-Producing cells specifically express two different forms of the endostatin precursor, collagen XVIII, in human liver cancers.

Endostatin is an endogenous inhibitor of angiogenesis and tumor growth in mice, which may be generated by proteolytic cleavage of collagen XVIII. In normal tissues, 2 variants of the endostatin precursor, namely the SHORT and LONG forms, regulate tissue specificity. We analyzed 53 human liver biopsies (18 hepatocellular carcinomas, 16 metastases of colorectal cancer, 3 cholangiocarcinomas, and 16 controls) by RNA dot blots, double-labeling immunohistochemistry, and in situ hybridization, using common and variant-specific probes. Tumor hepatocytes expressed the LONG form, whereas cholangiocarcinoma cells expressed the SHORT form, which was deposited in tumor basement membranes. Metastatic colorectal carcinoma cells did not express collagen XVIII. In the stromal compartment of primary and metastatic cancers, myofibroblasts and vascular endothelial cells expressed the SHORT form. Both basement membrane components, collagen IV and the SHORT collagen XVIII form, were codistributed and their mRNA levels strongly correlated (R =.75, P <.001). In addition, freshly isolated human hepatocytes expressed the LONG form and culture-activated stellate cells the SHORT form. Moreover, the full-length LONG form is a plasma protein. Thus, the LONG form is a hepatocyte-specific variant, and the SHORT form is a major component of the tumor extracellular matrix in primary and metastatic liver cancers. In the clinical context, the global expression of the endogenous endostatin precursor, collagen XVIII, in liver cancer results from the combined expression profiles of tumor cells, stromal cells, and nontumor hepatocytes at the advancing edge of the tumor, particular to each type of cancer.

Basement Membrane↗

PubMed2001

Induced repatterning of type XVIII collagen expression in ureter bud from kidney to lung type: association with sonic hedgehog and ectopic surfactant protein C.

Epithelial-mesenchymal tissue interactions regulate the formation of signaling centers that play a role in the coordination of organogenesis, but it is not clear how their activity leads to differences in organogenesis. We report that type XVIII collagen, which contains both a frizzled and an endostatin domain, is expressed throughout the respective epithelial bud at the initiation of lung and kidney organogenesis. It becomes localized to the epithelial tips in the lung during the early stages of epithelial branching, while its expression in the kidney is confined to the epithelial stalk region and is lost from the nearly formed ureter tips, thus displaying the reverse pattern to that in the lung. In recombinants, between ureter bud and lung mesenchyme, type XVIII collagen expression pattern in the ureter bud shifts from the kidney to the lung type, accompanied by a shift in sonic hedgehog expression in the epithelium. The lung mesenchyme is also sufficient to induce ectopic lung surfactant protein C expression in the ureter bud. Moreover, the shift in type XVIII collagen expression is associated with changes in ureter development, thus resembling aspects of early lung type epigenesis in the recombinants. Respecification of collagen is necessary for the repatterning process, as type XVIII collagen antibody blocking had no effect on ureter development in the intact kidney, whereas it reduced the number of epithelial tips in the lung and completely blocked ureter development with lung mesenchyme. Type XVIII collagen antibody blocking also led to a notable reduction in the expression of Wnt2, which is expressed in the lung mesenchyme but not in that of the kidney, suggesting a regulatory interaction between this collagen and Wnt2. Respecification also occurred in a chimeric organ containing the ureter bud and both kidney and lung mesenchymes, indicating that the epithelial tips can integrate the morphogenetic signals independently. A glial cell line-derived neurotrophic factor signal induces loss of type XVIII collagen from the ureter tips and renders the ureter bud competent for repatterning by lung mesenchyme-derived signals. Our data suggest that differential organ morphogenesis is regulated by an intra-organ patterning process that involves coordination between inductive signals and matrix molecules, such as type XVIII collagen.

Animals↗

PubMed2000

Coexpression of alpha and beta subunits of prolyl 4-hydroxylase stabilizes the triple helix of recombinant human type X collagen.

We have reported previously on the expression of recombinant human type X collagen (hrColX) in HEK 293 and HT 1080 cells by using the eukaryotic expression vector pCMVsis (in which CMV stands for cytomegalovirus). Several stably transfected clones secreted full-length triple-helical hrColX molecules in large amounts, but the secreted collagen was underhydroxylated, with a hydroxyproline-to-proline ratio of 0.25 and a melting temperature (T(m)) of 31 degrees C. By comparison, native chicken type X procollagen has a T(m) of 46 degrees C. To stabilize the triple helix of hrColX, an hrColX-expressing clone (A6/16) was co-transfected with both alpha and beta subunits of human prolyl 4-hydroxylase. Clones were selected that secreted proalpha1(X) collagen chains with an apparent molecular mass of 75 kDa and an increased hydroxyproline-to-proline ratio of close to 0.5. As a result of enhanced prolyl hydroxylation, the T(m) of the hrColX was increased to 41 degrees C as measured by CD analysis at various temperatures. The CD spectra indicated a minimum ellipticity at 198 nm and a peak at 225 nm at 20 degrees C, confirming the presence of a triple helix. The same T(m) of 41 degrees C was measured for the triple-helical core fragments of hrColX of 60-65 kDa that were retained after brief digestion with chymotrypsin/trypsin at increasing temperatures. This shows that the human cell line HEK-293 is suitable for the simultaneous expression of three genes and the stable production of substantial amounts of recombinant, fully hydroxylated type X collagen over several years.

Animals↗

PubMed2000

A short sequence in the N-terminal region is required for the trimerization of type XIII collagen and is conserved in other collagenous transmembrane proteins.

The recombinant transmembrane protein type XIII collagen is shown to reside on the plasma membrane of insect cells in a 'type II' orientation. Expressions of deletion constructs showed that sequences important for the association of three alpha1(XIII) chains reside in their N- rather than C-terminal portion. In particular, a deletion of residues 63-83 immediately adjacent to the transmembrane domain abolished the formation of disulfide-bonded trimers. The results imply that nucleation of the type XIII collagen triple helix occurs at the N-terminal region and that triple helix formation proceeds from the N- to the C-terminus, in opposite orientation to that of the fibrillar collagens. Interestingly, a sequence homologous to the deleted residues was found at the same plasma membrane-adjacent location in other collagenous transmembrane proteins, suggesting that it may be a conserved association domain. The type XIII collagen was secreted into insect cell medium in low amounts, but this secretion was markedly enhanced when the cytosolic portion was lacking. The cleavage occurred in the non-collagenous NC1 domain after four arginines and was inhibited by a furin protease inhibitor.

Amino Acid Sequence↗

PubMed2000

Type XIII collagen forms homotrimers with three triple helical collagenous domains and its association into disulfide-bonded trimers is enhanced by prolyl 4-hydroxylase.

Type XIII collagen is a type II transmembrane protein predicted to consist of a short cytosolic domain, a single transmembrane domain, and three collagenous domains flanked by noncollagenous sequences. Previous studies on mRNAs indicate that the structures of the collagenous domain closest to the cell membrane, COL1, the adjacent noncollagenous domain, NC2, and the C-terminal domains COL3 and NC4 are subject to alternative splicing. In order to extend studies of type XIII collagen from cDNAs to the protein level we have produced it in insect cells by means of baculoviruses. Type XIII collagen alpha chains were found to associate into disulfide-bonded trimers, and hydroxylation of proline residues dramatically enhanced this association. This protein contains altogether eight cysteine residues, and interchain disulfide bonds could be located in the NC1 domain and possibly at the junction of COL1 and NC2, while the two cysteine residues in NC4 are likely to form intrachain bonds. Pepsin and trypsin/chymotrypsin digestions indicated that the type XIII collagen alpha chains form homotrimers whose three collagenous domains are in triple helical conformation. The thermal stabilities (T(m)) of the COL1, COL2, and COL3 domains were 38, 49 and 40 degrees C, respectively. The T(m) of the central collagenous domain is unusually high, which in the light of this domain being invariant in terms of alternative splicing suggests that the central portion of the molecule may have an important role in the stability of the molecule. All in all, most of the type XIII collagen ectodomain appears to be present in triple helical conformation, which is in clear contrast to the short or highly interrupted triple helical domains of the other known collagenous transmembrane proteins.

Animals↗

PubMed2000

Distinct recognition of collagen subtypes by alpha(1)beta(1) and alpha(2)beta(1) integrins. Alpha(1)beta(1) mediates cell adhesion to type XIII collagen.

Two integrin-type collagen receptors, alpha(1)beta(1) and alpha(2)beta(1), are structurally very similar. However, cells can concomitantly express the both receptors and they might have independent functions. Here, Chinese hamster ovary (CHO) cells, which lack endogenous collagen receptors, were transfected with either alpha(1) or alpha(2) integrin cDNA. Cells were allowed to adhere to various collagen types and their integrin function was tested by observing the progression of cell spreading. The cells expressing alpha(1)beta(1) integrin could spread on collagen types I, III, IV, and V but not on type II, while alpha(2)beta(1) integrin could mediate cell spreading on collagen types I-V. Type XIII is a transmembrane collagen and its interaction with the integrins has not been previously studied. CHO-alpha1beta1 cells could spread on human recombinant type XIII collagen, unlike CHO-alpha2beta1 cells. Integrins alpha(1)beta(1) and alpha(2)beta(1) recognize collagens with the specific alphaI domains. The alpha(1)I and alpha(2)I domains were produced as recombinant proteins, labeled with europium and used in a sensitive solid-phase binding assay based on time-resolved fluorescence. alpha(1)I domain, unlike the alpha(2)I domain, could attach to type XIII collagen. The results indicate, that alpha(1)beta(1) and alpha(2)beta(1) have different ligand binding specificity. Distinct recognition of different collagen subtypes by the alphaI domains can partially explain the differences seen in cell spreading. However, despite the fact that CHO-alpha1beta1 cells could not spread on type II collagen alpha(1)I domain could bind to this collagen type. Thus, the cell spreading on collagens may also be regulated by factors other than the integrins.

Animals↗

PubMed2000

Type XIII collagen is widely expressed in the adult and developing human eye and accentuated in the ciliary muscle, the optic nerve and the neural retina.

The distribution of mRNAs coding for type XIII collagen, a novel nonfibril-forming collagen, was studied by Northern and in situ hybridizations of adult and fetal human eyes and the corresponding protein was localized by indirect immunofluorescence in frozen sections of 12 and 17 week human fetal eyes using a polyclonal antipeptide antibody to type XIII collagen. Type XIII collagen was found to be widely expressed in ocular tissues when studied at both the mRNA and protein levels in fetal and adult human tissues. No major differences were observed in the expression patterns between fetal and adult tissues. Surprisingly, the strongest signals seen in in situ hybridizations and immunofluorescence stainings occurred in the optic nerve bundles and in the ganglion cell layer of the retina. Other notable locations containing type XIII collagen included the developing ciliary smooth muscle, the posterior two-thirds of the corneal stroma and the striated extraocular muscles. Low level signals were also detected in the blood vessel walls and mesenchymal cells of the other ocular tissues. All immunosignals detected were adherent to cells, and the extracellular matrices appeared to be devoid of type XIII collagen. Our results are in concert with the presumed plasma membrane location of type XIII collagen, and it is hypothesized that this molecule could be involved in cell-matrix and perhaps cell-cell interactions. The wide expression of type XIII collagen in the eye, and especially in the neural structures, warrants future studies on type XIII collagen in other nerve structures and in pathological conditions affecting the eye. Due to its wide expression, type XIII collagen is likely to be an important factor for the normal development and functioning of the eye.

Adult↗

PubMed2000

Structure of the mouse type XV collagen gene, Col15a1, comparison with the human COL15A1 gene and functional analysis of the promoters of both genes.

Isolation and characterization of the mouse gene for the alpha1 chain of type XV collagen (Col15a1) revealed it to be approximately 110 kb in length and contain 40 exons. Analysis of the proximal 5'-flanking region showed properties characteristic of a housekeeping gene promoter, such as an absence of TATA and CAAT boxes, the presence of several transcriptional start sites and a high G+C content. The general organization of the mouse Col15a1 gene was found to be highly similar to that of its human homologue, but the genomic area encoding the end of the N-terminal non-collagenous domain showed marked divergence from the human form. Furthermore, two exons coding for the N-terminal collagenous domain of the human alpha1(XV) chain are lacking in the mouse Col15a1 gene. Due to the lack of two exons and a codon divergence in one exon, the mouse alpha1(XV) chain contains seven collagenous domains, whereas the human equivalent contains nine. Comparison of 5'-flanking sequences indicated four domains that were conserved between the mouse and human genes. Functional analysis of the mouse promoter identified cis-acting elements for both positive and negative regulation of Col15a1 gene expression in mouse NIH/3T3 cells.

3T3 Cells↗