Biomedical subjects

Y Ninomiya

Publications and source records attributed to Y Ninomiya.

At least 19 recordsLinked to original sources

PubMed1999

Differential tissular expression and localization of type IV collagen alpha1(IV), alpha2(IV), alpha5(IV), and alpha6(IV) chains and their mRNA in normal breast and in benign and malignant breast tumors.

Type IV collagen, the major component of basement membrane (BM), is composed of six genetically distinct alpha chains. We investigated the cellular regulation and origin of these alpha(IV) chains in normal and neoplastic breast tissues by immunohistochemistry by using alpha(IV) chain-specific antibodies and by in situ hybridization. In normal breast, alpha1(IV) and alpha2(IV) chains were stained in all BM, whereas alpha5(IV) and alpha6(IV) chains were restrictively localized in a linear pattern in the BM of the mammary gland. Similar immunostaining profiles were observed in benign breast tumors and in the intraductal components of invasive ductal carcinoma. However, in invasive ductal carcinoma, alpha1(IV) and alpha2(1V) chains were discontinuously or negatively stained in the cancer cell nests, and the assembly of alpha5(IV) and alpha6(IV) chains into the BM was completely inhibited. Coexpression of alpha5(IV) and alpha6(IV) chains was related to the localization of alpha-smooth muscle actin (alpha-SMA)-positive myoepithelial cells. By in situ hybridization, in fibroadenoma and invasive ductal carcinoma, the signals for alpha1(IV) and alpha2(IV) mRNA were abundant in stromal cells. However, the signals for alpha5(IV) and alpha6(IV) mRNA were not seen in any of these cells. In contrast, in intraductal papilloma, coexpression of alpha1 (IV)/alpha2(IV) mRNA and alpha5(IV)/alpha6(IV) mRNA was identified in epithelial cells. The results indicate that the mammary gland forms a second network of BM composed of alpha5(IV)/alpha6(IV) chains, in addition to the classic network of alpha1(IV)/alpha2(IV) chains. The expression of type IV collagen alpha chains seems to be differentially regulated by the epithelial-myoepithelial interaction and to be associated with the invasive potential of breast cancer.

Breast↗

PubMed1999

Intra-tumor injection of an angiogenesis inhibitor, TNP-470, in rabbits bearing VX2 carcinoma of the tongue.

A semi-synthetic analogue of fumagillin, TNP-470, has been shown to be a potent angiogenesis inhibitor. In this study, we evaluated the anti-tumor efficacy of TNP-470 on rabbits bearing VX2 carcinoma of the tongue, by comparison of topical, intra-tumor (i.t.) injection with systemic, intra-venous (i.v.) administration. The i.t. injection of the angiogenesis inhibitor produced much stronger anti-tumor effects, and almost complete tumor regression was achieved at doses of 10 mg/kg or 20 mg/kg. TNP-470 injected intra-tumorally significantly reduced expression of proliferating cell nuclear antigen (PCNA) and microvessel density in the VX2 carcinoma of the tongue. TNP-470 also halted the tumor-associated neovascularization in the rabbit cornea assay. These data suggest that i.t. injection of TNP-470 effectively inhibits tumor angiogenesis and disrupts microvasculature development, which may suppress tumor growth. In conclusion, the i.t. injection of TNP-470 provided remarkable anti-tumor effects on the VX2 carcinoma of the tongue and is expected to have promising therapeutic uses for oral cancer.

Animals↗

PubMed1999

New form of X-linked dominant hereditary nephritis in dogs.

OBJECTIVE: To determine features of a new form of hereditary nephritis (HN) in dogs. ANIMALS: Parents and 16 first-generation offspring (8 males, 8 females). PROCEDURE: Adolescent dogs that developed renal failure were euthanatized and necropsied. Unaffected dogs were monitored until they were at least 2 years old. Studies included light and electron microscopy of kidneys obtained from affected and unaffected dogs and immunolabeling for collagen-IV chains in renal and epidermal basement membranes (BM). The nucleotide sequence of a portion of exon 35 of the COL4A5 gene was determined in genomic DNA isolated from affected and unaffected males. RESULTS: 7 of 8 male and 2 of 8 female offspring had proteinuria and juvenile-onset chronic renal failure, which progressed more rapidly in the males. Labeling for alpha3-alpha6(IV) chains was completely absent in renal BM of affected males and segmentally absent in affected females. Expression of alpha1-alpha2(IV) chains in glomerular BM (GBM) of affected dogs was increased. Labeling for alpha5-alpha6(IV) chains in epidermal BM was absent in affected males and segmental in affected females. Ultrastructural changes characteristic of HN were observed in GBM of affected dogs. The sequence of exon 35 of COL4A5 was normal in affected dogs. CONCLUSIONS: This renal disease is an example of X-linked dominant HN, with typical abnormalities of GBM ultrastructure and alpha(IV) chain expression. CLINICAL RELEVANCE AND IMPLICATIONS FOR HUMAN MEDICINE: Dogs with this naturally acquired progressive renal disease can be used to investigate the pathogenesis and treatment of similar disorders in human beings and dogs.

Animals↗

PubMed1999

Reperfusion accelerates the distribution of type I and III collagen messenger RNA expression after acute myocardial infarction: in situ hybridization in experimental infarction in rats.

BACKGROUND: The effects of reperfusion on the time-dependent appearance and distribution of type I and III collagen messenger RNA (mRNA) expression had not hitherto been examined. OBJECTIVE: To compare the sequential changes in the extent of distribution of type I and III collagen mRNA expression in reperfused infarct hearts of rats with those in unreperfused infarct hearts. METHODS: Using an experimental rat model of infarction, we examined type I and III collagen mRNA expression with specific rat pro alpha 1 (I) and human pro alpha 1 (III) collagen riboprobes by in-situ hybridization. Reperfusion was established after a 2 h coronary ligation that produced complete necrosis of the myocytes. RESULTS: Positive signals both for alpha 1 (I) and for alpha 1 (III) collagen mRNA appeared in the infarct peripheral zone 12 h after coronary ligation both of the reperfused and of unreperfused hearts. The spread of signal into the infarct central zone occurred 1-2 days earlier for the reperfused hearts than it did for the unreperfused hearts. The difference between the distributions of signals for the reperfused and unreperfused hearts became obscure on day 14. No notable difference between the extents of signal distribution for alpha 1 (I) and alpha 1 (III) collagen mRNA was obtained. We observed intense signals from spindle-shaped mesenchymal cells (myofibroblasts and fibroblasts) located between surviving myocytes in the marginal zone of the infarct. No myocyte exhibited signals both for alpha 1 (I) and for alpha 1 (III) collagen mRNA. CONCLUSION: In the present study, using in-situ hybridization, we demonstrated that reperfusion accelerates the distribution of expression both of alpha 1 (I) and of alpha 1 (III) collagen mRNA in the infarct zone after acute myocardial infarction in rats.

Animals↗

PubMed1998

Taste in chimpanzees. III: Labeled-line coding in sweet taste.

In peripheral taste the coding mechanism remains an enigma. Among coding theories the "across-fiber pattern" argues that activity across fibers codes for taste, whereas the "labeled line" claims that activity in a particular set of fibers underlies a taste quality. We showed previously that chimpanzee chorda tympani taste fibers grouped according to human taste qualities into an S-cluster, responding predominantly to sweet stimuli, a Q-cluster, sensitive to bitter tastants, and an N-cluster, stimulated by salts. The analysis showed that information in the S-line suffices to distinguish stimuli of one taste quality from the others. However, one condition for the labeled line remained: that blockage of activity in a particular line must cause blockage of one taste quality, but of no other, or its onset give rise to the sensation of a taste quality. Here we studied this requirement with gymnemic acids and miraculin. In humans and chimpanzees, gymnemic acids suppress the sweet taste of all sweeteners whereas miraculin adds a sweet taste quality to sour stimuli. Gymnemic acids also abolish miraculin-induced sweet taste. We found that gymnemic acids practically abolished the response to every sweetener in the chimpanzee S-cluster. Equally important, they had no effect on the responses of the Q- and N-clusters. After miraculin, the S-cluster fibers responded to acids as well as to sweeteners, although they had not responded to acids before miraculin. Gymnemic acids abolished this miraculin-induced response to acids and responses to sweeteners in the S-fibers. These results link the sweet taste quality to activity in fibers of the S-cluster. Thus the S-cluster fibers satisfy the definition of the labeled-line theory: "that activity in a particular fiber type represents a specific taste quality."

Animals↗

PubMed1998

Initiation of skin basement membrane formation at the epidermo-dermal interface involves assembly of laminins through binding to cell membrane receptors.

To study the mechanism of basement membrane formation, we determined by immunochemistry temporal and spatial expression of laminin-5 (Ln-5), laminin-1 (Ln-1) and their integrin receptors during early skin morphogenesis. A 3-dimensional skin culture was used that allows the study of the sequential molecular events of basement membrane formation at the epidermodermal interface. During early anchorage of keratinocytes to the extracellular matrix there is expression of Ln-5, BP-230 antigen and alpha3, beta1 integrin subunits. During epidermal stratification and prior to the formation of the lamina densa there is assembly of Ln-5, Ln-1, collagen IV and nidogen accompanied by keratinocyte basal clustering of alpha2, alpha3, alpha6, beta1, and beta4+ integrin subunits. The assembly pattern of Ln-1 and Ln-5 can be disturbed with functional antibodies against the beta1 (AIIB2) and alpha6 (GoH3) integrin subunits. Ln-1 assembly can also be disturbed with antibodies against its E8 domain and by competitive inhibition with a synthetic peptide (AG-73) derived from its G-4 domain. Quantitative RT-PCR showed that the dermis contributes about 80% of the laminin gamma)1 chain mRNA while 20% is produced by the epidermis which emphasizes its dual tissue origin and the major contribution of the mesenchyma in laminin production. The laminin gamma2 chain mRNA, present in Ln-5, was mostly of epidermal origin. This study presents evidence that during the initiation of basement membrane formation, laminins bind to keratinocyte plasma membrane receptors and thus may serve as nucleation sites for further polymerization of these compounds by a self-assembly process.

Actin Cytoskeleton↗

PubMed1998

cDNA sequence and expression of the mouse alpha1(V) collagen gene (Col5a1).

Several overlapping cDNA clones corresponding to the entire coding sequence of the mouse alpha1(V) collagen gene (Col5a1) were isolated. The conceptual amino acid translation indicated a high degree of sequence identity (94%) with the human alpha1(V) chain. All of the important structures previously noted in the human alpha1(V) chain were also conserved in the mouse chain. The alpha1(V) transcripts were easily detected in mouse embryos as early as 11 days post coitum (d.p.c.). The transcripts were widely distributed in non-cartilaginous and cartilaginous tissues. Finally, we calculated the ratio of transcripts of alpha1(V):alpha2(V):alpha1(XI) in the calvaria and tongue of 18 d.p.c. embryos using the competitive reverse transcription-polymerase chain reaction (RT-PCR) technique. The results raised the possibility that there are at least two different kind of types V/XI collagen heterotrimers in mouse embryonic tissues.

Amino Acid Sequence↗

PubMed1998

Decoy administration of NF-kappaB into the subarachnoid space for cerebral angiopathy.

Subarachnoid hemorrhage (SAH), encephalitis, meningitis, and autoimmune diseases sometimes lead to cerebral angiopathy, characterized specifically by narrowing of vessels, morphological changes in the structure of vessel walls, and a concomitant decrease in cerebral blood flow. Many patients also develop delayed ischemic neurological deficits. Thus, preventing vascular reactions is of paramount importance in treating SAH. Although cerebral vasospasm has some relationship with the inflammatory reaction of major cerebral vessels against the autologous blood, and many trials have attempted to prevent angiopathy after SAH, an effective treatment has not yet been established. The purpose of this article is to evaluate the preventive effect of nuclear factor KB (NF-kappaB) decoy oligo-DNA after SAH; since NF-kappaB is closely related to inflammation. In the rabbit angiopathy model after SAH, we evaluated the effectiveness of the decoy oligo-DNA using the angiographic (digital subtraction angiography) and histological (hematoxylin-eosin and Masson's trichrome staining) methods. Moreover, a gel-shift assay for NF-kappaB was also performed in order to evaluate the activity of NF-kappaB. We describe a new concept for treating cerebral angiopathy after SAH and for successfully inhibiting cerebral vasospasm and morphological changes in vessel walls in a rabbit model. In this treatment, we used synthetic double-strand oligo-DNA with a high affinity for transcription factor NF-kappaB, and cationic liposome complex administered through the cerebrospinal fluid.

Animals↗

PubMed1998

Reinnervation of cross-regenerated gustatory nerve fibers into amiloride-sensitive and amiloride-insensitive taste receptor cells.

Single nerve fiber responses to NaCl and their inhibition by amiloride were compared among the chorda tympani (CT) and glossopharyngeal (IXth), and their cross-regenerated nerves in the C57BL/KsJ mice. The CT nerve innervating the anterior part of the tongue contained approximately equal numbers of two types of NaCl-responsive neurons; one type showed strong suppression of NaCl responses by amiloride [amiloride-sensitive (AS) type], and the other type showed only weak or no suppression of NaCl responses by amiloride [amiloride-insensitive (AI) type]. In contrast, the IXth nerve innervating the posterior part of the tongue has almost exclusively the AI type. This relative abundance of the AS and AI types of fibers was not altered by cross-regeneration of the two gustatory nerves into the reverse tongue regions. This suggests that regenerated taste axons selectively recouple with the appropriate type of receptor cell whether they innervate the front or the back of the tongue. Such selective synapse reformation may help explain the stability of response profiles of taste neurons during continual receptor cell turnover.

Amiloride↗

PubMed1998

High affinity binding of latent matrix metalloproteinase-9 to the alpha2(IV) chain of collagen IV.

Association of matrix metalloproteinases (MMPs) with the cell surface and with areas of cell-matrix contacts is critical for extracellular matrix degradation. Previously, we showed the surface association of pro-MMP-9 in human breast epithelial MCF10A cells. Here, we have characterized the binding parameters of pro-MMP-9 and show that the enzyme binds with high affinity (Kd approximately 22 nM) to MCF10A cells and other cell lines. Binding of pro-MMP-9 to MCF10A cells does not result in zymogen activation and is not followed by ligand internalization, even after complex formation with tissue inhibitor of metalloproteinase-1 (TIMP-1). A 190-kDa cell surface protein was identified by ligand blot analysis and affinity purification with immobilized pro-MMP-9. Microsequencing and immunoblot analysis revealed that the 190-kDa protein is the alpha2(IV) chain of collagen IV. Specific pro-MMP-9 surface binding was competed with purified alpha2(IV) and was significantly reduced after treatment of the cells with active MMP-9 before the binding assay since alpha2(IV) is hydrolyzed by MMP-9. A pro-MMP-9.TIMP-1 complex and MMP-9 bind to alpha2(IV), suggesting that neither the C-terminal nor the N-terminal domain of the enzyme is directly involved in alpha2(IV) binding. The closely related pro-MMP-2 exhibits a weaker affinity for alpha2(IV) compared with that of pro-MMP-9, suggesting that sites other than the gelatin-binding domain may be involved in the binding of alpha2(IV) to pro-MMP-9. Although pro-MMP-9 forms a complex with alpha2(IV), the proenzyme does not bind to triple-helical collagen IV. These studies suggest a unique interaction between pro-MMP-9 and alpha2(IV) that may play a role in targeting the zymogen to cell-matrix contacts and in the degradation of the collagen IV network.

Animals↗

PubMed1998

Glomerular basement membrane. Identification of a novel disulfide-cross-linked network of alpha3, alpha4, and alpha5 chains of type IV collagen and its implications for the pathogenesis of Alport syndrome.

Glomerular basement membrane (GBM) plays a crucial function in the ultrafiltration of blood plasma by the kidney. This function is impaired in Alport syndrome, a hereditary disorder that is caused by mutations in the gene encoding type IV collagen, but it is not known how the mutations lead to a defective GBM. In the present study, the supramolecular organization of type IV collagen of GBM was investigated. This was accomplished by using pseudolysin (EC 3.4.24.26) digestion to excise truncated triple-helical protomers for structural studies. Two distinct sets of truncated protomers were solubilized, one at 4 degrees C and the other at 25 degrees C, and their chain composition was determined by use of monoclonal antibodies. The 4 degrees C protomers comprise the alpha1(IV) and alpha2(IV) chains, whereas the 25 degrees C protomers comprised mainly alpha3(IV), alpha4(IV), and alpha5(IV) chains along with some alpha1(IV) and alpha2(IV) chains. The structure of the 25 degrees C protomers was examined by electron microscopy and was found to be characterized by a network containing loops and supercoiled triple helices, which are stabilized by disulfide cross-links between alpha3(IV), alpha4(IV), and alpha5(IV) chains. These results establish a conceptual framework to explain several features of the GBM abnormalities of Alport syndrome. In particular, the alpha3(IV). alpha4(IV).alpha5(IV) network, involving a covalent linkage between these chains, suggests a molecular basis for the conundrum in which mutations in the gene encoding the alpha5(IV) chain cause defective assembly of not only alpha5(IV) chain but also the alpha3(IV) and alpha4(IV) chains in the GBM of patients with Alport syndrome.

Animals↗

PubMed1998

Two genes, COL4A3 and COL4A4 coding for the human alpha3(IV) and alpha4(IV) collagen chains are arranged head-to-head on chromosome 2q36.

We first isolated and characterized genomic DNA fragments that cover the 5' flanking sequences of COL4A3 and COL4A4 encoding the human basement membrane alpha3(IV) and alpha4(IV) collagen chains, respectively. Nucleotide sequence analysis indicated that the two genes are arranged head-to-head. To determine transcription start site for COL4A4 gene, we performed RACE and RNase protection assays, indicating that there are two alternative transcripts presumably derived from two different promoters. Interestingly, one transcription start site (from exon 1') of COL4A4 is only 5 bp away from the reported transcription start site of COL4A3, whereas the other transcript (from exon 1) starts 373 nucleotides downstream from the first one, generating the two kinds of transcripts that differ in the 5' UTR regions. Expression of these two transcripts appears tissue-specific; exon 1 transcript was expressed predominantly in epithelial cells, while exon 1' transcript showed rather ubiquitous and low expression. The nucleotide sequence of the promoter region is composed of dense CpG dinucleotides, GC boxes, CTC boxes and a CCAAT box but no TATA box. These results provide information to delineate the promoter activity for the tissue-specific expression of the six type IV collagen genes and basement membrane assembly in different tissues and organs.

Alternative Splicing↗

PubMed1998

Extracellular matrix changes in human corneas after radial keratotomy.

Extracellular matrix and basement membrane alterations were identified in human corneas after radial keratotomy. Ten normal and five radial keratotomy autopsy corneas (two at 6 months post surgery, and three at 3 years post surgery) were studied by immunofluorescence with antibodies to 28 extracellular matrix and basement membrane components. Outside of radial keratotomy scars, all studied components had a normal distribution. Of stromal extracellular matrix, only type III collagen accumulated around the scars. The basement membrane around epithelial plugs had a normal composition except for type IV collagen. Its alpha1-alpha2 chains, normally present only in the limbal basement membrane, appeared around all plugs. alpha3 and alpha4 chains were very weak or absent in these areas, contrary to nonscarred areas. This basement membrane pattern was similar to the normal limbal but not to the central corneal pattern. Keratin 3 also had a limbal-like, suprabasal expression in the plug epithelium. The stroma around the scars accumulated tenascin-C, fibrillin-1, types VIII and XIV collagen, all of which were absent from normal corneal basement membrane and extracellular matrix. Only tenascin-C showed less staining in anterior scars 3 years post surgery than 6 months post surgery, but still persisted in posterior scars. Incomplete scar healing was evident even 3 years post radial keratotomy. It was manifested by the accumulation of abnormal extracellular matrix in the anterior and posterior scars and by the limbal-like pattern of type IV collagen isoforms in the basement membrane around epithelial plugs.

Adult↗

PubMed1998

Expression of the alpha 1 and alpha 2 chains of type IV collagen in the infarct zone of rat myocardial infarction.

Healing processes affect ventricular remodeling, an important prognostic factor in acute myocardial infarction (AMI). Type IV collagen, a major component of the basement membrane, has been demonstrated to appear in the infarct zone. Six type IV alpha chains, alpha 1 to alpha 6 [alpha 1(IV) to alpha 6(IV)], have been identified. We examined the expression of the alpha 1(IV), alpha 2(IV), alpha 3(IV) and alpha 5(IV) in experimental rat AMI induced by permanent ligation of the left coronary artery in male Sprague-Dawley rats. Neonatal cardiac fibroblasts cultured to reach confluency were also used to examine the hypoxic induction of the expression of these chains. Northern blotting, in situ hybridization, and immunohistochemical staining were employed to examine the alpha chain expression. With the in situ hybridization, alpha 1(IV) and alpha 2(IV) mRNA signals were observed in spindle-shaped mesenchymal cells in the intercellular spaces, in the vascular endothelial cells and in some myocytes in the normal myocardium. Signals for both alpha 1(IV) and alpha 2(IV) mRNA appeared in the spindle-shaped mesenchymal cells located between the surviving myocytes in the infarct peripheral zone at 24 h after the ligation. These signals extended into the central zone and reached the center point of the infarct 5 days after the ligation. Neither alpha 3(IV) nor alpha 5(IV) mRNA signals were observed in the infarct zone. Northern blotting demonstrated increased expressions of alpha 1(IV) and alpha 2(IV) mRNA in the infarct zone compared to the sham-operated hearts. The expression of alpha 5(IV) mRNA was weak in the sham-operated hearts but was not detected in the infarct zone. alpha 3(IV) mRNA was not expressed in the infarct zones or sham-operated hearts. In the cultured cardiac fibroblasts, a hypoxic induction of the expression of both alpha 1(IV) and alpha 2(IV) mRNA was demonstrated by Northern hybridization. Immunohistochemistry revealed alpha 1(IV) and alpha 2(IV) staining in the infarct lesion. The findings demonstrate that among the type IV collagen alpha chains examined, alpha 1(IV) and alpha 2(IV) produced by mesenchymal cells appeared in the infarct zone, suggesting that type IV collagen composed by alpha 1 and alpha 2 chains contributes to the pathological course of myocardial infarction.

Animals↗

PubMed1998

Increase in the expression of biglycan mRNA expression Co-localized closely with that of type I collagen mRNA in the infarct zone after experimentally-induced myocardial infarction in rats.

Biglycan, a small dermatan sulphate proteoglycan, has been postulated to interact with other components of the extracellular matrix (ECM), specifically collagens. We hypothesized that biglycan messenger ribonucleic acid (mRNA) is increased in the myocardial infarct zone. Biglycan mRNA expression after acute myocardial infarction (AMI) in rats was determined with the use of Northern blotting and in situ hybridization, and its expression pattern was compared to that of type I collagen mRNA [alpha1(I) collagen]. The left coronary artery was ligated in male Sprague-Dawley rats, and the hearts were excised on days 2 and 7. The Northern blot analysis demonstrated that expression of biglycan mRNA in the infarct on days 2 and 7 were 4.0- and 6.8-fold higher, respectively, compared to the sham-operated hearts. The in situ hybridization revealed intense signals for both biglycan and alpha1(I) collagen mRNA on day 2 in the spindle-shaped mesenchymal cells located between the surviving myocytes in the infarct peripheral zone. On day 7, biglycan mRNA signals were observed in the interior of the infarct around the infarct granulation tissue, a distribution that was essentially the same as that of alpha1(I) collagen. These results demonstrated that the increases in the infarct biglycan mRNA expression produced by mesenchymal cells (presumably myofibroblasts and fibroblasts) was closely co-localized with that of type I collagen mRNA, indicating that biglycan contributes to the infarct healing processes.

Animals↗

PubMed1998

Increased expression of connective tissue growth factor in the infarct zone of experimentally induced myocardial infarction in rats.

Connective tissue growth factor (CTGF), a 36- to 38-kDa peptide, is selectively induced by transforming growth factor-beta and has been suggested to contribute to tissue repair. To test the hypothesis that CTGF is expressed in myocardial infarct tissue following acute myocardial infarction (AMI), we examined CTGF expression after AMI was experimentally induced in rats. Myocardial infarction was induced by left coronary artery ligation in male Sprague-Dawley rats. Northern blotting demonstrated that the CTGF mRNA expression on days 2, 7 and 14 was increased by 6-, 23- and 8-fold, respectively, compared to that in the pre-ligation hearts. In situ hybridization revealed CTGF mRNA signals on day 2 in myocytes in the infarct marginal zone and spindle-shaped mesenchymal cells (presumably myofibroblasts and fibroblasts) located between surviving myocytes in the infarct peripheral zone. On day 7, the signals were observed in the inner lesion of the infarct around infarct granulation tissue. Western blotting demonstrated that the CTGF protein expression on days 2, 7 and 14 was increased compared to the pre-ligation hearts. Immunopositive staining for CTGF was observed in the inner lesion of the infarct tissue on day 7. In conclusion, the findings demonstrated the increased expression of CTGF in the infarct tissue. Myocytes in the infarct marginal zone and spindle-shaped mesenchymal cells (presumably myofibroblasts and fibroblasts) were the cells responsible for CTGF production.

Animals↗

PubMed1998

Differential expression of type IV collagen isoforms, alpha5(IV) and alpha6(IV) chains, in basement membranes surrounding smooth muscle cells.

Smooth muscle is composed of cigar-shaped, non-striated cells, each of which is encapsulated by a basement membrane and forms the contractile portion of tubular organs such as the gastrointestinal tract, pulmonary tract, genitourinary tract, and vasculature, in which slow and sustained contractions are needed. We examined basement membranes produced by smooth muscle cells and, using alpha(IV) chain-specific monoclonal antibodies, analyzed type IV collagens in these organs. Detailed distribution analysis of the alpha chains in normal and Alport cases by use of specific antibodies indicated that there are at least three molecular forms of type IV collagen, [alpha1(IV)]2alpha2(IV),alpha3(IV)alpha4(IV)alpha5+ ++(IV), and alpha5(IV)/alpha6(IV). Smooth muscle cells in the urinary bladder and uterus were enclosed by basement membranes composed of alpha1, alpha2, alpha5, and alpha6 chains. The same alpha chains were present around smooth muscle cells in the muscular layer of the fundus of the stomach, whereas those in the antrum and further distal side of the gastrointestinal tract expressed mostly alphal and alpha2 chains. In addition, immunostaining analysis of the vasculature also showed that most of the smooth muscle cells were positive for alpha1 and alpha2 chains; however, alpha5 and alpha6 chains were also expressed by smooth muscle cells in the aorta and some arteries where blood pressure changes significantly. These results suggest that the smooth muscle cells enclosed by alpha5/alpha6-containing basement membranes might have some particular function related to mechanical stress or tensile strength during the characteristic contractile activity of tubular organs.

Amino Acid Sequence↗

PubMed1998

Sequential changes in the localization of the type IV collagen alpha chain in the infarct zone: immunohistochemical study of experimental myocardial infarction in the rat.

Collagen, as a component of the extracellular matrix, have a role in the healing process after myocardial infarction (MI). For type IV collagen, a major structural protein present in the basal membrane of myocytes, six alpha chains [alpha 1 (IV)-alpha 6(IV)] have been identified. We examined the sequential changes in the appearance and localization of the alpha 1 (IV)-alpha 5(IV) after experimental MI in rats. Hearts were excised from 1 day to 8 weeks after permanent left coronary artery ligation. Immunohistochemical staining with monoclonal antibodies was performed. On day 3, staining for both alpha 1(IV) and alpha 2(IV) first appeared, forming a wavy pattern in the infarct peripheral zone, and the staining was not restricted to the cell membrane. The staining intensity and distribution for both alpha 1(IV) and alpha 2(IV) in the peripheral zone then gradually increased, reaching a maximum around day 7. The distribution progressed from the peripheral to the central zone of the infarct for 1-2 days, reaching the center point after 2 weeks. The staining distribution gradually decreased after reaching the maximum, but the staining had not completely disappeared at 8 weeks. In contrast, no positive staining for alpha 3(IV), alpha 4(IV) or alpha 5(IV) was observed at any time during the 8-week observation period. Thus, the present results demonstrated that in rats, type IV collagen consisting of alpha 1 and alpha 2 chains appears in the infarct zone at a relatively early phase after MI, indicating that type IV collagen composed of alpha 1 and alpha 2 chains contributes to infarct healing.

Animals↗