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L P Zhang

Publications and source records attributed to L P Zhang.

At least 19 recordsLinked to original sources
PubMed2006

Characterization of metallothioneins (MT-I and MT-II) in the yak.

The cDNA-encoding sequences for yak metallothionein isoforms I (MT-I) and II (MT-II) were amplified and cloned by reverse-transcription PCR to characterize the nucleotide sequence and protein structure of metallothionein in the yak. The cDNA sequences of MT-I and MT-II were subjected to BLAST searching at the National Center for Biotechnology Information, and the results indicated that the nucleotide sequences of yak MT-I and MT-II, when compared among different species of mammals, are highly conserved. The yak open reading frames have a length of 183 nucleotides, which encode for yak MT-I and MT-II proteins of 61 AA, respectively. Analysis of hydrophobicity, trans-membrane region, and signal peptides suggested that metallothioneins of the yak are nonsecretory proteins. There were several conserved tripeptide sequences, such as C-X-C, C-C-X-C-C, and C-X-X-C (X designates AA excluding cysteine in MT-I and MT-II), and they are highly conserved in their evolution. By homologous comparative modeling, we predicted the molecular spatial structures of yak MT-I and MT-II, which are composed of alpha- and beta-domains that are linked by the conserved tripeptide Lys(30)-Lys(31)-Ser(32) (KKS).

Amino Acid Sequence↗
PubMed2003

Genetics of drought tolerance during seed germination in tomato: inheritance and QTL mapping.

A BC1 population (N = 1000) of an F1 hybrid between a stress-sensitive Lycopersicon esculentum breeding line (NC84173; maternal and recurrent parent) and a germination stress-tolerant Lycopersicon pimpinellifolium accession (LA722) was evaluated for seed germination rate under drought stress (DS) (14% w/v polyethyleneglycol-8000, water potential approximately -680 kPa), and the most rapidly germinating seeds (first 3% to germinate) were selected. The 30 selected BC1 seedlings were grown to maturity and self pollinated to produce BC1S1 progeny seeds. Twenty of the 30 selected BC1S1 progeny families were evaluated for germination rate under DS and their average performance was compared with that of a "nonselected" BC1S1 population of the same cross. Results indicated that selection for rapid germination under DS significantly improved progeny germination rate under DS (selection gain = 19.6%), suggesting a realized heritability of 0.47 for rate of germination under DS in this population. The 30 selected BC1 plants were subjected to restriction fragment length polymorphism (RFLP) analysis, and marker allele frequencies for 119 RFLP markers which spanned 1153 cM of the 12 tomato chromosomes were determined. A distributional extreme marker analysis, which measures statistical differences in marker allele frequencies between a selected and a nonselected population, detected four quantitative trait loci (QTLs) for rate of germination under DS in this population. Of these, two QTLs, located on chromosomes 1 and 9, were contributed by the L. pimpinellifolium donor parent and had larger effects than the other two QTLs, located on chromosomes 8 and 12, which were contributed by the L. esculentum recurrent parent. A few BC1S1 families were identified with all or most of the identified QTLs and with germination rates comparable with that of LA722. These families should be useful for the development of germination drought-tolerant tomato lines using marker-assisted selection (MAS). The overall results indicate that drought tolerance during seed germination in tomato is genetically controlled and potentially could be improved by directional phenotypic selection or MAS.

Chromosome Mapping↗
PubMed2002

A molecular linkage map of tomato displaying chromosomal locations of resistance gene analogs based on a Lycopersicon esculentum x Lycopersicon hirsutum cross.

A molecular linkage map of tomato was constructed based on a BC1 population (N = 145) of a cross between Lycopersicon esculentum Mill. line NC84173 (maternal and recurrent parent) and Lycopersicon hirsutum Humb. and Bonpl. accession PI126445. NC84173 is an advanced breeding line that is resistant to several tomato diseases, not including early blight (EB) and late blight (LB). PI126445 is a self-incompatible accession that is resistant to many tomato diseases, including EB and LB. The map included 142 restriction fragment length polymorphism (RFLP) markers and 29 resistance gene analogs (RGAs). RGA loci were identified by PCR amplification of genomic DNA from the BC1 population, using ten pairs of degenerate oligonucleotide primers designed based on conserved leucine-rich repeat (LRR), nucleotide binding site (NBS), and serine (threonine) protein kinase (PtoKin) domains of known resistance genes (R genes). The PCR-amplified DNAs were separated by denaturing polyacrylamide gel electrophoresis (PAGE), which allowed separation of heterogeneous products and identification and mapping of individual RGA loci. The map spanned 1469 cM of the 12 tomato chromosomes with an average marker distance of 8.6 cM. The RGA loci were mapped to 9 of the 12 tomato chromosomes. Locations of some RGAs coincided with locations of several known tomato R genes or quantitative resistance loci (QRLs), including Cf-1, Cf-4, Cf-9, Cf-ECP2, rx-1, and Cm1.1 (chromosome 1); Tm-1 (chromosome 2); Asc (chrromosme 3); Pto, Fen, and Prf (chromosome 5); 01-1, Mi, Ty-1, Cm6.1, Cf-2, CF-5, Bw-5, and Bw-1 (chromosome 6); I-1, 1-3, and Ph-1 (chromosome 7); Tm-2a and Fr1 (chromosome 9); and Lv (chromosome 12). These co-localizations indicate that the RGA loci were either linked to or part of the known R genes. Furthermore, similar to that for many R gene families, several RGA loci were found in clusters, suggesting their potential evolutionary relationship with R genes. Comparisons of the present map with other molecular linkage maps of tomato, including the high density L. esculentum x Lycopersicon pennellii map, indicated that the lengths of the maps and linear order of RFLP markers were in good agreement, though certain chromosomal regions were less consistent than others in terms of the frequency of recombination. The present map provides a basis for identification and mapping of genes and QTLs for disease resistance and other desirable traits in PI126445 and other L. hirsutum accessions, and will be useful for marker-assisted selection and map-based gene cloning in tomato.

Chromosome Mapping↗
PubMed2001

Effects of Matrine on proliferation and differentiation in K-562 cells.

We investigated the effects of Matrine on proliferation by trypan blue exclusion and differentiation by benzidine staining positive cells in K-562 cells, assayed the telomerase activity using PCR-ELISA assay, analyzed cell cycle by fluorescence-activated cell sorter analysis of the DNA content, and also determined the gene expression level of c-myc, N-ras and p53 by northern blot and dot blot analysis. The results showed that with the addition of 0.1 mg/ml Matrine, cell growth was inhibited significantly by 4 days, benizidine-positive cells rose from 1% to 2% in control cells to 15% in treated cells on day 5; treatment of K-562 cells with 0.1 mg/ml Matrine for 5 days resulted in a marked inhibition in telomerase activity, in a manner that correlated with the extent of differentiation; after exposure to Matrine for 72 h, 64.6% cells were arrested in the G1-phase of the cell cycle, the fraction of cells in S-phase had decreased from 56.9% in control cells to 24.4% in differentiated cells, and the levels of N-ras and p53 mRNA were remarkably increased for 24 and 48 h, respectively, c-myc mRNA expression level declined for 24 h and was inhibited significantly for 48 h. Our study confirmed that Matrine plays a significant effect on the inhibition of proliferation cells and inducing differentiation in K-562 cells.

Alkaloids↗
PubMed2001

Streptimonospora salina gen. nov., sp. nov., a new member of the family Nocardiopsaceae.

Actinomycete strain YIM 90002T (= CCTCC 99003T = CCRC 16284T) was isolated from a soil sample collected from a salt lake in the west of China. The aerial mycelium of this organism is well developed but not fragmented and, at maturity, forms short chains of spores. Spores in short chains are oval- to rod-shaped and have wrinkled surfaces. Substrate mycelium is branched with non-fragmenting hyphae and forms single oval to round spores borne on sporophores or dichotomously branching sporophores. Single spores have wrinkled surfaces. Single spores and spores in short chains are non-motile. Strain YIM 90002T contains meso-diaminopimelic acid, DD-diaminopimelic acid, glycine, lysine and aspartic acid in its cell wall and has glucose, galactose, ribose, xylose, arabinose and mannose as whole-cell sugars (no diagnostic sugars). The phospholipids are phosphatidylglycerol, phosphatidylinositol and phosphatidylethanolamine. The major menaquinones are MK-9(H6), MK-10(H2) and MK-10(H4). Phylogenetic data indicate that this strain belongs to the family Nocardiopsaceae. The morphological and physiological characteristics and chemotaxonomic and phylogenetic data for this strain differ from those of previously described actinomycetes. Therefore, a new genus, Streptimonospora, is proposed for this organism; the type species of the genus is Streptimonospora salina gen. nov., sp. nov., and the type strain of S. salina is strain YIM 90002T.

Actinomycetales↗
PubMed2001

Identification and validation of QTLs for salt tolerance during vegetative growth in tomato by selective genotyping.

The purpose of this study was to identify quantitative trait loci (QTLs) for salt tolerance (ST) during vegetative growth (VG) in tomato by distributional extreme analysis and compare them with the QTLs previously identified for this trait. A BC1 population (N = 792) of a cross between a moderately salt-sensitive Lycopersicon esculentum Mill. breeding line (NC84173, maternal and recurrent parent) and a salt-tolerant L. pimpinellifolium (Jusl.) Mill. accession (LA722) was evaluated for ST in solution cultures containing 700 mM NaCl + 70 mM CaCl2 (electrical conductivity, EC = 64 dS/m and phiw approximately -35.2 bars). Thirty-seven BC1 plants (4.7% of the total) that exhibited the highest ST were selected (referred to as the selected population), grown to maturity in greenhouse pots and self-pollinated to produce BC1S1 progeny seeds. The 37 selected BC1S1 progeny families were evaluated for ST and their average performance was compared with that of the parental BC1 population before selection. A realized heritability of 0.50 was obtained for ST in this population. The 37 selected BC1 plants were subjected to restriction fragment length polymorphism (RFLP) analysis using 115 markers, and marker allele frequencies were determined. Allele frequencies for the same markers were also determined in an unselected BC1 population (N = 119) of the same cross. A trait-based marker analysis (TBA), which measures differences in marker allele frequencies between selected and unselected populations, was used to identify marker-linked QTLs. Five genomic regions were detected on chromosomes 1, 3, 5, 6, and 11 bearing significant QTLs for ST. Except for the QTL on chromosome 3, all QTLs had positive alleles contributed from the salt tolerant parent LA722. Of the five QTLs, three (those on chromosomes 1, 3, and 5) were previously identified for this trait in another study, and thus were validated here. Only one of the major QTLs that was identified in our previous study was not detected here. This high level of conformity between the results of the two studies indicates the genuine nature of the identified QTLs and their potential usefulness for ST breeding using marker-assisted selection (MAS). A few BC1S1 families were identified with most or all of the QTLs and with a ST comparable to that of LA722. These families should be useful for the development of salt tolerant tomato lines via MAS.

Breeding↗
PubMed2001

[Separation of xylose and xylitol in fermentation liquid by capillary zone electrophoresis].

Xylitol may be produced with microbial fermentation technology when xylose is used as the raw material. It is important in scientific research and production fields concerned with xylose and xylitol to develop the method of separation and detection. The anionic complexes with strong UV absorption at 195 nm will form by dissolving xylose and xylitol in borax solution. They may be separated with borax buffer by use of capillary zone electrophoresis. It was shown that the resolution between xylose and xylitol gradually increased with the increase of borax concentration, but its maximum concentration was 130 mmol/L at room temperature. The resolution depended on the pH of running buffer with a maximum at pH 9.55. The resolution was independent of cetyltrimethylammonium bromide when its concentration was between 4 x 10(-6) mmol/L-8 x 10(-4) mmol/L. So the optimum conditions were as follows: borax concentration of 130 mmol/L, pH 9.55 and cetyltrimethylammonium bromide concentration of 5 x 10(-5) mmol/L in running buffer; separating voltage of -12 kV; column temperature of 25 degrees C. Xylose and xylitol could be separated on base line in 6 min under these conditions. Samples from fermentation process and the recoveries of spiked samples were determined. The relative standard deviations of the results were between 1.42%-3.11% for xylose, and 0.62%-1.32% for xylitol. The recoveries were between 96.0%-108.0% for xylose and 94.0%-109.0% for xylitol.

Electrophoresis, Capillary↗
PubMed2001

[Effects of growth regulator, full exposure and mist spray on the cutting of Eucommia ulmoides].

OBJECTIVE: To study the effects of growth regulator on the cutting method of Eucommia ulmoides seedlings. METHODS: Treated with H2O (CK), NAA, 6-BA and NAA + 6-BA for 4 hours, respectively, cuttings of 4-year and 20-year trees were cultured for 45-60 days under the shed or full exposure and mist spray. The growth of the cuttings was observed periodically. The number of the roots, the root length, the callus and the death rate were investigated after harvest. RESULTS: Compared with the cutting from 4-year-old tree, the cutting from 20-year-old tree developed better. The rate of stroking root in treated group was 14 times as much as CK group. Other agronomic traits such as the number of the roots, the root length, the callus, the number of the leaves and the death rate of the cuttings in treated group were all better than that of the cuttings in CK group. The cultural time in treated group reduced by 15 days than that of CK group. CONCLUSIONS: The present study shows that both full exposure mist spray and growth regulators have remarkable effects on cuttings of tree with different ages for rooting or forming callus.

Eucommiaceae↗
PubMed2000

[Investigation on growth and development of Tussilago farfara L. in Beijing].

OBJECTIVE: To provide a scientific basis for the introduction and harvest of T. farfara in Beijing. METHOD: Random sampling in late growing period. RESULT: T. farfara reached the peak of vegetation growth in early September and concurrently began its reproductive growth. During this period its bud and rhizome began to form and develop and kept growing until the period of freezing weather. CONCLUSION: There are two optimum the times for reaping T. farara bud: one is around the fifteenth day before the period of freezing weather, and the other is around the tenth day after the thawing season in the next year.

Asteraceae↗
PubMed2000

[Effect of storage methods on breaking seed dormancy of Trollius chinensis Bge].

OBJECTIVE: Exploring the best seed storage method for Trollius chinensis. METHOD: Different temperatures were applied to the seed storage in wet sand and dry sand, and the embryo-endosperm ratio and germination rate were inspected. RESULT: The dormancy of T. chinensis seeds could only be broken in lower temperatures. The newly collected seeds set out to germinate after 75 days of storage at 5-6 degrees C when the embryo-endosperm ratio reached 47%, and the time of seed germination varied with the length of storage time before low-temperature treatment. CONCLUSION: The best storage method for the seed of T. chinensis is keeping it in dry for 6-8 months with an additional 1 month of low-temperature treatment to follow.

Drug Storage↗
PubMed1999

Characterization of an oxygen/redox-dependent degradation domain of hypoxia-inducible factor alpha (HIF-alpha) proteins.

Hypoxia-inducible factors are heterodimeric DNA-binding complexes that control the hypoxia responses of several genes and regulate the adaptive responses to the lack of oxygen. The complex is composed of two b-HLH protein subunits, HIF-1beta (ARNT), that is constitutively expressed, and a HIF-alpha subunit, that is present only in hypoxic cells. HIF-alpha proteins are continuously synthesized, but are rapidly degraded by the ubiquitin-proteasome system under oxic conditions. Hypoxia, transition metals, iron chelators, and several antioxidants stabilize the HIF-alpha proteins, allowing the formation of the transcriptionally active HIF complex. However, the sequences and mechanisms involved in the regulated degradation of the alpha protein subunits are poorly understood. Analysis of the available cloned sequences of human and mouse members of the HIF-alpha family of proteins revealed an area of about 15 amino acids with strong sequence conservation between all the members. This area corresponds to the region encompassing amino acids 557-571 of the hHIF-1alpha subunit. Fragments of HIF-1alpha and HIF-3alpha proteins containing this conserved sequence were able to confer hypoxia regulation when expressed as fusion proteins in Hep-3B cells. Regulation was observed with all the known hypoxia "mimics," including the reducing thiol donor N-mercaptopropionylglycine (NMPG). Selective alanine substitutions of amino acids 561-568 stabilized the protein in normoxic conditions. Furthermore, transfection with an expression vector containing a fragment of hHIF-1alpha comprising amino acids 540-580 enhanced transactivation activity of the full-length hHIF-1alpha protein. These results suggest that the above-mentioned conserved sequences are likely involved in the hypoxic stabilization of HIF-alpha proteins. The mechanisms and the interacting ubiquitin-ligases involved in the selective degradation process remain unknown.

Amino Acid Sequence↗
PubMed1999

Expression of matrix metalloproteinase-13 and tissue inhibitor of metalloproteinase-1 in acute liver injury.

BACKGROUND/AIMS: Matrix metalloproteinase-13, one of the principal neutral proteinases capable of cleaving native fibrillar collagens, is important in the degradation and remodeling of extracellular matrix. However, its precise expression in liver injury has not been characterized. We examined the kinetics of the expression of matrix metalloproteinase-13 and one of its specific inhibitors, tissue inhibitor of metalloproteinase-1, in acute liver injury in rats. METHODS: Acute liver injury was induced by administration of carbon tetrachloride or two different doses of D-galactosamine hydrochloride in Wistar rats. Hepatic matrix metalloproteinase-13 and tissue inhibitor of metalloproteinase-1 mRNA levels were then examined by Northern blotting. RESULTS: All rats survived after liver injury induced by carbon tetrachloride or low doses of D-galactosamine hydrochloride. However, rats died 5 days after induction of liver injury by high doses of D-galactosamine hydrochloride. In carbon tetrachloride-induced liver injury, matrix metalloproteinase-13 mRNA was transiently increased between 6 h and 1 day after injury. Tissue inhibitor of metalloproteinase-1 mRNA expression was increased between 6 h and 3 days after the peak of matrix metalloproteinase-13 expression. Similar patterns of matrix metalloproteinase-13 and tissue inhibitor of metalloproteinase-1 expression were observed in low-dose D-galactosamine hydrochloride-induced liver injury. In contrast, in high-dose D-galactosamine hydrochloride-induced liver injury, tissue inhibitor of metalloproteinase-1 expression peaked before matrix metalloproteinase-13 expression, which was increased 2 days after injury. Both mRNA levels continued to increase until death. CONCLUSIONS: Transient expression of matrix metalloproteinase-13, followed by that of tissue inhibitor of metalloproteinase-1, was observed during recovery from acute liver injury induced by carbon tetrachloride and low-dose D-galactosamine hydrochloride. In contrast, disordered expression of matrix metalloproteinase-13 was observed in fatal liver injury caused by high-dose D-galactosamine hydrochloride. These results indicate that matrix metalloproteinase13 plays an important role in the early phase of recovery from liver injury.

Animals↗
PubMed1999

Spatial distribution of tissue inhibitor of metalloproteinase-1 mRNA in chronic liver disease.

BACKGROUND/AIMS: Tissue inhibitor of metalloproteinase-1, a specific inhibitor of matrix metalloproteinases, plays an important role in the pathogenesis of fibrosis and tumor progression. However, the precise expression of tissue inhibitor of metalloproteinase-1 messenger RNA in human hepatic fibrosis has not yet been defined. We investigated the spatial distribution of tissue inhibitor of metalloproteinase-1 messenger RNA in chronic human liver disease. METHODS: Northern and in situ hybridization of probes to tissue inhibitor of metalloproteinase-1 messenger RNA were performed in specimens from 16 surgically resected human livers. Immunohistochemical staining of sections for tissue inhibitor of metalloproteinase-1 and immunoelectron microscopy were also performed. RESULTS: Northern hybridization demonstrated that expression of tissue inhibitor of metalloproteinase-1 messenger RNA was increased 3.9-fold in mild chronic hepatitis, 6.8-fold in moderate chronic hepatitis, and 6.4-fold in cirrhosis, compared with control liver. In situ hybridization showed the expression of tissue inhibitor of metalloproteinase-1 messenger RNA in spindle-shaped cells in the fibrous septa and lobules in chronic hepatitis and cirrhosis; these cells were immunohistochemically positive for a-smooth muscle actin. Immunoelectron microscopy revealed localization of tissue inhibitor of metalloproteinase-1 in between fibers, to the rough endoplasmic reticula of stellate cells located in the lobules and periportal areas, and to fibroblasts in the fibrous septa. These results indicate that tissue inhibitor of metalloproteinase-1 was produced mainly by stellate cells in the specimens of chronic liver diseases. CONCLUSIONS: Expression of tissue inhibitor of metalloproteinase-1 messenger RNA is increased in hepatic fibrosis and stellate cells are involved primarily in its expression.

Adult↗
PubMed1999

Increased expression of plasminogen activator and plasminogen activator inhibitor during liver fibrogenesis of rats: role of stellate cells.

BACKGROUND/AIMS: Plasminogen activators and plasminogen activator inhibitors are important regulators of the balance between the proteolytic and antiproteolytic activities that determine extracellular matrix turnover. We examined the expression of plasminogen activator-plasmin system components in experimental liver fibrosis of rats. METHODS: Liver fibrosis was produced in rats by injecting carbon tetrachloride for 6 to 12 weeks. Gene expression for plasminogen activator inhibitor-1 (PAI-1), urokinase and tissue plasminogen activators (uPA and tPA), urokinase plasminogen activator receptor (uPAR), and transforming growth factor-beta1 (TGF-beta1) was examined by Northern analysis. Western analysis was performed to detect protein expression of PAI-1, uPA and uPAR. An immunohistochemical study was performed to detect the localization of PAI-1. Additionally, primary cultured liver cells were examined by Northern and Western analyses for this protein with or without prior incubation with TGF-beta1. RESULTS: At 6 weeks, when fibrosis had occurred, uPA and uPAR mRNAs had increased 2.8-fold and 1.8-fold, respectively; PAI-1 and tPA mRNA levels were unchanged. At the cirrhotic stage (9 to 12 weeks), mRNA levels for PAI-1, uPA, uPAR and tPA were all increased. Western analysis also showed increased uPA and uPAR expressions in fibrotic liver, and increased PAI-1, uPA and uPAR expressions in cirrhotic liver. PAI-1 protein was also demonstrated immunohistochemically along sinusoids, vessels, and bile duct cells of normal and fibrotic liver. In liver cell cultures, Kupffer cells, hepatocytes, and especially stellate cells, expressed PAI-1. Expression was enhanced in stellate cells cultured from fibrotic or cirrhotic liver or stimulated in vitro with TGF-beta1. CONCLUSION: Though increased uPA and uPAR may act on matrix degradation in fibrotic liver, increased PAI-1 together with uPA, uPAR and tPA are associated with overall inhibition of matrix degradation in cirrhotic liver. Hepatic stellate cells are an important source of PAI-1 during liver fibrosis.

Animals↗
PubMed1999

Multiple elements influence transcriptional regulation from the human testis-specific PGK2 promoter in transgenic mice.

The PGK2 gene is expressed in a strictly tissue-specific manner in meiotic spermatocytes and postmeiotic spermatids during spermatogenesis in eutherian mammals. Previous results indicate that this is regulated at the transcriptional level by core promoter sequences that bind ubiquitous transcription factors and by sequences in a 40-base pair (bp) upstream enhancer region (E1/E4) that bind tissue-specific transcription factors. Transgenic mice carrying different PGK2 promoter sequences linked to the chloramphenicol acetyltransferase (CAT) reporter gene, one containing only the 40-bp E1/E4 enhancer sequence plus the core promoter and two containing 515 bp of PGK2 promoter but with either the E1/E4 enhancer region or the Sp1-binding site in the core promoter disrupted by in vitro mutagenesis, all showed levels of expression reduced to less than half that of the wild-type 515 PGK2/CAT transgene. These results indicate that multiple factor-binding regions normally regulate initiation of transcription from the PGK2 promoter. The single disruption of any one of these binding activities reduced, but did not abolish, transgene expression. This is consistent with an "enhanceosome"-like function in this promoter involving multiple bound activator proteins that interact in a combinatorial manner to synergistically promote testis-specific transcription.

Animals↗
PubMed1998

A gene-specific promoter in transgenic mice directs testis-specific demethylation prior to transcriptional activation In vivo.

Transcription of the autosomal phosphoglycerate kinase gene, Pgk-2, is initiated at the onset of meiosis during spermatogenesis in mammals. However, in the mouse, the 5' portion of the endogenous Pgk-2 coding sequence undergoes a specific demethylation event that precedes transcriptional activation by 10-12 days. Here we show that transgenes consisting of the Pgk-2 core promoter ligated to the CAT reporter gene undergo a similar tissue-, stage-, and cell type-specific demethylation in the 5' portion of the CAT coding sequence, whereas transgenes consisting of the CAT reporter sequence alone, or of the CAT sequence ligated to the CpG island-containing transferrin gene promoter, demonstrate different patterns of demethylation. These results indicate that specific promoter sequences can influence the pattern of tissue-specific demethylation within different genes and that a signal for spermatogenic cell-specific demethylation resides within the core promoter of the mammalian Pgk-2 gene.

Animals↗
PubMed1997

Dual expression of matrix metalloproteinase-2 and membrane-type 1-matrix metalloproteinase in fibrotic human livers.

We have previously reported increased expression of matrix metalloproteinase-2 (MMP-2) using a rat model of liver fibrosis. However we did not clarify how the precursor of MMP-2 (proMMP-2) was activated. Therefore, we used human liver specimens with chronic hepatitis (CH) and liver cirrhosis (LC) to examine expression of membrane-type-1-MMP (MT1-MMP), which has recently been determined to activate proMMP-2. Northern hybridization studies showed a 5.4- and 1.4-fold increase in MMP-2 expression in CH and LC, respectively, as compared with normal liver. MT1-MMP gene expression simultaneously increased 4.0- and 1.4-fold in CH and LC, respectively. In situ hybridization using 35S-cRNA probes of MMP-2 and MT1-MMP showed prominent silver granules in elongated cells found in the lobules, periportal areas, and fibrous septa of CH and LC samples. These elongated cells expressed alpha-smooth muscle actin by immunohistochemistry. Immunoelectron microscopic examination localized MMP-2 and MT1-MMP to the rough endoplasmic reticulum of stellate cells located in the lobules and periportal areas, or to fibroblasts in the fibrous septa, suggesting that MMP-2 and MT1-MMP were produced by these cells. In addition, cytoplasmic and membranous immunodeposits of both MMPs were found in endothelial cells, Kupffer cells, capillary endothelial cells, and lymphocytes, indicating that activation of proMMP-2 occurs locally. Increased expression of MMP-2 and MT1-MMP was detected in CH and LC, while dual over-expression was found in stellate cells and fibroblasts, possibly resulting in the increase of active MMP-2 in and around these cells. These findings suggest that activated MMP-2 may remodel liver parenchyma during the process of liver fibrosis.

Adult↗