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Biomedical subjects

E Vuorio

Publications and source records attributed to E Vuorio.

At least 37 records · Page 2Linked to original sources
PubMed2001

Differential expression patterns of cathepsins B, H, K, L and S in the mouse ovary.

Cathepsins B, H, K, L and S belong to a family of lysosomal cysteine proteinases which participate in a variety of proteolytic processes, including degradation of extracellular matrix. Although the presence of cathepsin mRNAs in the ovary has been reported earlier, very little information is available on their temporospatial expression. In the present study, Northern analysis revealed cyclic changes in the mRNA levels for cathepsins B, H, K, L and S during the 4-day oestrous cycle in the mouse ovary. Immunohistochemical localization revealed distinct expression patterns suggesting different functions for the cathepsins studied. Cathepsin B was predominantly seen in the germinal epithelium throughout the oestrous cycle. Upon follicular maturation, an increasing number of granulosa cells became positive for all cathepsins. Strong cathepsin H staining was sharply defined in theca externa which also stained for cathepsins K and S. Corpus luteum was the predominant location of cathepsin L. The distribution of cathepsin S resembled that of cathepsin L. The developing oocyte stained positive for all cathepsins. In-situ hybridization confirmed the differential production of cathepsin mRNAs by granulosa, thecal and luteal cells. These complex temporal and spatial expression patterns at different stages of the oestrous cycle and follicular development suggest divergent functions for specific cathepsins in follicular development, growth and rupture.

Animals↗
PubMed2001

Expression patterns of cathepsins B, H, K, L and S in the human endometrium.

Cathepsins B, H, K, L and S belong to the family of lysosomal cysteine proteinases and participate in a variety of proteolytic processes, including degradation of the extracellular matrix (ECM). In the present study, we used Northern hybridization to demonstrate the presence of mRNAs for cathepsins B, H, K, L and S in human endometrium during both the proliferative and secretory phases of menstrual cycle. The mRNA levels for cathepsins H and K were significantly lower in secretory phase endometrium in comparison with proliferative phase endometrium. Immunohistochemical localization of the different cathepsins revealed widespread distribution of all cathepsins in both stroma and epithelial cells. The immunoreactivity for cathepsins B, H and K exhibited changes related to endometrial location and/or to the phase of the cycle. The strongest immunoreactivity for cathepsins B, H, L and S was observed in the surface epithelium of the endometrium. The staining for cathepsins was predominantly intracellular, but immunoreactivity was also detected on the surface of small lymphoid cells in the stroma. The findings of the present study suggest that cysteine cathepsins are needed for normal development and function of human endometrium during both the proliferative and secretory phases.

Adult↗
PubMed2001

Accelerated up-regulation of L-Sox5, Sox6, and Sox9 by BMP-2 gene transfer during murine fracture healing.

Fracture repair is the best-characterized situation in which activation of chondrogenesis takes place in an adult organism. To better understand the mechanisms that regulate chondrogenic differentiation of mesenchymal progenitor cells during fracture repair, we have investigated the participation of transcription factors L-Sox5, Sox6, and Sox9 in this process. Marked up-regulation of L-Sox5 and Sox9 messenger RNA (mRNA) and smaller changes in Sox6 mRNA levels were observed in RNAse protection assays during early stages of callus formation, followed by up-regulation of type II collagen production. During cartilage expansion, the colocalization of L-Sox5, Sox6, and Sox9 by immunohistochemistry and type II collagen transcripts by in situ hybridization confirmed a close relationship of these transcription factors with the chondrocyte phenotype and cartilage production. On chondrocyte hypertrophy, production of L-Sox5, Sox9 and type II collagen were down-regulated markedly and that of type X collagen was up-regulated. Finally, using adenovirus mediated bone morphogenetic protein 2 (BMP-2) gene transfer into fracture site we showed accelerated up-regulation of the genes for all three Sox proteins and type II collagen in fractures treated with BMP-2 when compared with control fractures. These data suggest that L-Sox5, Sox6, and Sox9 are involved in the activation and maintenance of chondrogenesis during fracture healing and that enhancement of chondrogenesis by BMP-2 is mediated via an L-Sox5/Sox6/Sox9-dependent pathway.

Animals↗
PubMed2001

Accelerated turnover of metaphyseal trabecular bone in mice overexpressing cathepsin K.

This study is based on a hypothesis that overexpression of an osteoclast enzyme, cathepsin K, causes an imbalance in bone remodeling toward bone loss. The hypothesis was tested in transgenic (TG) mice harboring additional copies of the murine cathepsin K gene (Ctsk) identifiable by a silent mutation engineered into the construct. For this study, three TG mouse lines harboring 3-25 copies of the transgene were selected. Tissue specificity of transgene expression was determined by Northern analysis, which revealed up to 6-fold increases in the levels of cathepsin K messenger RNA (mRNA) in calvarial and long bone samples of the three TG lines. No changes were seen in the mRNA levels of other osteoclast enzymes, indicating that the increase in cathepsin K mRNA was not a reflection of activation of all osteoclast enzymes. Immunohistochemistry confirmed that cathepsin K expression in the TG mice was confined to osteoclasts and chondroclasts. Histomorphometry revealed a significantly decreased trabecular bone volume (BV), but, surprisingly, also a marked increase in the number of osteoblasts, the rate of bone turnover, and the amount of mineralizing surface (MS). However, monitoring of bone density in the proximal tibias of the TG mice with peripheral quantitative computed tomography (pQCT) failed to reveal statistically significant changes in bone density. Similarly, no statistically significant alterations were observed in biomechanical testing at the age of 7 months. The increases in parameters of bone formation triggered by increased cathepsin K expression is an example of the tight coupling of bone resorption and formation during the bone-remodeling cycle.

Animals↗
PubMed2001

Activation of chondrogenesis in response to injury in normal and transgenic mice with cartilage collagen mutations.

OBJECTIVE: The aim of this report is to describe and discuss the reparative capacity of articular cartilage by focusing on similarities and differences in the activation of chondrogenesis in adult bone and cartilage in response to injury. DESIGN: The present report describes three different models of skeletal repair in the mouse. Two of the models deal with bone healing, where the activation of chondrogenesis and formation of callus tissue is greatly dependent on the rigidity of fixation. The third comprises two transgenic mouse models for osteoarthritis where dominant negative mutations in cartilage-specific genes disturb the structural integrity of the cartilage collagen fibrils. RESULTS: Molecular biologic and immunohistochemical analyses demonstrated that activation of chondrogenesis in healing fractures, i.e., activation and maintenance of the chondrocyte phenotype was preceded by increased production and nuclear accumulation of transcription factor SOX9. A similar, albeit smaller, chondrogenic response was observed during healing of biomechanically stable metaphyseal bone defects. In degenerating articular cartilage of transgenic mice, however, the production of cartilage-specific collagen types and SOX9 was markedly reduced upon aging which probably explains why repair of cartilage defects was insufficient. CONCLUSION: Understanding of the molecular mechanisms involved in successful and unsuccessful activation of chondrogenesis during skeletal repair, will provide information needed for enhancement of the chondrocytic response at sites of skeletal repair. Our data also demonstrates that specific effector molecules can be efficiently introduced into chondrocytes and their precursors by adenovirus-mediated gene transfer.

Animals↗
PubMed2000

Up-regulation of cartilage oligomeric matrix protein at the onset of articular cartilage degeneration in a transgenic mouse model of osteoarthritis.

OBJECTIVE: To investigate the suitability of cartilage oligomeric matrix protein (COMP) as a marker for articular cartilage degeneration in a transgenic mouse model of osteoarthritis (OA). METHODS: Northern blot analysis of total RNA extracted from the knee joints of transgenic Del1 mice, which harbor a short deletion in a type II collagen transgene, and of their nontransgenic littermates was used to monitor changes in COMP messenger RNA (mRNA) levels during cartilage degeneration. Immunohistochemistry was used to determine the distribution of COMP in articular cartilage, and serum levels of COMP were measured by immunoassay. RESULTS: Transient up-regulation of COMP mRNA was seen in articular cartilage of transgenic Del1 mice at the onset of OA lesions at the age of 3 months. Compared with nontransgenic controls, COMP immunostaining of articular cartilage in 3-9-month-old transgenic mice was increased, especially at the border of uncalcified and calcified cartilage. There was also a change from predominantly interterritorial to pericellular/territorial deposition of COMP. This difference persisted until the age of 15 months, when the nontransgenic controls also demonstrated articular cartilage degeneration and increased COMP immunostaining. Increased serum levels of COMP were seen in Del1 mice at the age of 4 months, correlating temporally with the onset of cartilage degeneration. CONCLUSION: These findings suggest that upregulation of COMP mRNA and redistribution of the protein are characteristic of the early stages of articular cartilage degeneration in the transgenic mouse model in which OA results from a dominant-negative mutation in the type II collagen gene. The data provide additional support for the notion that COMP is a useful marker for altered cartilage metabolism in developing OA.

Animals↗
PubMed2000

Expression of cathepsins B, H, K, L, and S and matrix metalloproteinases 9 and 13 during chondrocyte hypertrophy and endochondral ossification in mouse fracture callus.

Fracture repair provides an interesting model for chondrogenesis and osteogenesis as it recapitulates in an adult organism the same steps encountered during embryonic skeletal development and growth. The fracture callus is not only a site of rapid production of cartilage and bone, but also a site of extensive degradation of their extracellular matrices. The present study was initiated to increase our understanding of the roles of different proteolytic enzymes, cysteine cathepsins B, H, K, L, and S, and matrix metalloproteinases (MMPs) 9 and 13, during fracture repair, as this aspect of bone repair has previously received little attention. Northern analysis revealed marked upregulation of cathepsin K, MMP-9, and MMP-13 mRNAs during the first and second weeks of healing. The expression profiles of these mRNAs were similar with that of osteoclastic marker enzyme tartrate-resistant alkaline phosphatate (TRAP). The changes in the mRNA levels of cathepsins B, H, L, and S were smaller when compared with those of the other enzymes studied. Immunohistochemistry and in situ hybridization confirmed the predominant localization of cathepsin K and MMP-9 and their mRNA in osteoclasts and chondroclasts at the osteochondral junction. MMP-13 was present in osteoblasts and individual hypertrophic chondrocytes near the cartilage-bone interphase. In cartilaginous callus, the expression of cathepsins B, H, L, and S was mainly related to chondrocyte hypertrophy. During bone remodeling both osteoblasts and osteoclasts contained these cathepsins. The present data demonstrate that degradation and remodeling of extracellular matrices during fracture healing involves activation of MMP-13 production in hypertrophic chondrocytes and osteoblasts, and cathepsin K and MMP-9 production in osteoclasts and chondroclasts.

Animals↗
PubMed2000

Temporospatial expression of tissue inhibitors of matrix metalloproteinases-1, -2 and -3 during development, growth and aging of the mouse skeleton.

Proteolytic degradation of collagen-rich extracellular matrices is a key feature in the development, growth and aging of skeleton. Matrix metalloproteinases (MMPs) are a family of enzymes capable of performing this function, whereas tissue inhibitors of MMPs (TIMPs) are believed to play an important role in regulating their activity. To better understand the roles of TIMP-1, -2 and -3, we have studied their mRNA levels in several different mouse tissues with special emphasis on the skeleton and the developing eye. A systematic analysis of TIMP-1, -2 and -3 mRNA levels in mouse knee joints during growth and aging demonstrated markedly different expression patterns for each TIMP. Immunohistochemical analysis revealed several time-dependent changes in the distribution of TIMP-1 and -2 in articular and growth cartilages, synovial tissue and bone. The data suggest that upon aging synovial tissue becomes the major source of synovial fluid TIMPs. In articular cartilage these inhibitors were mainly found in the deep layer and in subchondral bone. Compared with epiphyseal growth plate, the amounts of TIMP-1 and -2 in articular cartilage were quite low. These findings suggest that the capacity of articular cartilage chondrocytes to inhibit MMP activities by local production of TIMPs is limited, which may be of consequence during osteoarthritic cartilage degeneration.

Aging↗
PubMed2000

Antisense RNA inhibition of cathepsin L expression reduces tumorigenicity of malignant cells.

Several tumour-forming cell lines are known to overproduce the lysosomal cysteine peptidase cathepsin L. We have used an antisense approach to investigate whether inhibition of cathepsin L overexpression in two malignant cell lines (myeloma SP cells and L cells) reduces their tumorigenic potential. Two different cDNA fragments of murine cathepsin L were inserted in the antisense direction into the pcDNA3 vector, and SP and L cells were stably transfected with these plasmid constructs. Several of the selected clones expressing the antisense transcript showed specific reduction of the mRNA level and the intracellular activity of cathepsin L, and a greatly diminished amount of secreted procathepsin L. When tested in Balb/c nu/nu mice, the cell lines with low cathepsin L activity exhibited a significantly decreased potential for tumour growth when compared with control cells expressing wild-type levels of cathepsin L activity. This observation suggests that cathepsin L is a critical factor in tumour growth.

Animals↗
PubMed1999

Characterization of recombinant human type IX collagen. Association of alpha chains into homotrimeric and heterotrimeric molecules.

As type IX collagen is a minor cartilage component, it is difficult to purify sufficient amounts of it from tissues or cultured cells to study its structure and function. Also, the conventional pepsin digestion used for fibrillar collagens cannot be utilized for purifying type IX collagen, because it contains several interruptions in its collagenous triple helix. A baculovirus expression system was used here to produce recombinant human type IX collagen by coinfecting insect cells with three viruses containing full-length cDNAs for the alpha1(IX), alpha2(IX), and alpha3(IX) collagen chains together with a double promoter virus for the alpha and beta subunits of human prolyl 4-hydroxylase. Correctly folded recombinant type IX collagen was secreted, consisting of the three alpha chains in a 1:1:1 ratio and showing the expected biphasic thermal melting profile. When the individual alpha chains were expressed, disulfide-bonded homotrimers and homodimers of the alpha chains were observed. When the cells were coinfected with the viruses for all three alpha chains, heterotrimers of alpha1(IX), alpha2(IX), and alpha3(IX) were detected in cell culture medium, and the other possible combinations were less prominent. When any two of the alpha chains were co-expressed, in addition to the homodimers and homotrimers, only alpha1(IX) and alpha3(IX) chains were disulfide-bonded. The results thus suggest that the most favored molecular species is an alpha1(IX)alpha2(IX)alpha3(IX) heterotrimer, but the chains are also able to form disulfide-bonded heterotrimers of alpha1(IX) and alpha3(IX) chains and (alpha1(IX))(3), (alpha2(IX))(3), and (alpha3(IX))(3) homotrimers.

Amino Acids↗
PubMed1999

Cathepsin expression during skeletal development.

Cysteine proteinases, cathepsins B, H, K, L and S, have been implicated in several proteolytic processes during development, growth, remodeling and aging, as well as in a variety of pathological processes. For systematic analysis of cathepsin gene expression we have produced cDNA clones for mouse and human cysteine cathepsins. Northern analysis of a panel of total RNAs isolated from 16-19 different human and mouse tissues revealed the presence of mRNAs for cathepsin B, H, K, L and S in most tissues, but each with a distinct profile. Of the different cathepsin mRNAs, those for cathepsin K were clearly the highest in bone and cartilage. However, relatively high mRNA levels for the other cathepsins were also present in these tissues. To better understand the roles of different cathepsins during endochondral ossification in mouse long bones, cathepsin mRNAs were localized by in situ hybridization. Cathepsin K mRNAs were predominantly seen in multinucleated chondroclastic and osteoclastic cells at the osteochondral junction and on the surface of bone spicules. The other cathepsin mRNAs were also seen in osteoclasts, and in hypertrophic and proliferating chondrocytes. These observations were confirmed by immunohistochemistry and suggest that all cysteine cathepsins are involved in matrix degradation during endochondral ossification.

Amino Acid Sequence↗
PubMed1999

Complete genomic structure of the mouse cathepsin K gene (Ctsk) and its localization next to the Arnt gene on mouse chromosome 3.

In preparation for gene manipulative experiments in mice we have isolated genomic clones covering the entire murine cathepsin K gene (Ctsk). Sequence analysis revealed that the gene spans 10.1 kb and contains eight exons and seven introns. The sizes of the coding exons 2-7 as well as the pattern of intron sizes are conserved between the human and mouse cathepsin K genes. Genomic organization of the mouse cathepsin K gene also closely resembles those of cathepsins S and L. More than 26% of the Ctsk sequence consists of different repetitive elements. Detailed sequence analysis of 1.7 kb of Ctsk promoter revealed several putative binding sites for transcription factors and two stretches of 280-320 bp which were > 70% homologous with the human cathepsin K promoter. Analysis of genomic clones extending further upstream of the Ctsk gene identified the 3' end of the gene coding for arylhydrocarbon-receptor nuclear translocator (Arnt). This places Ctsk approximately 4.5 kb downstream of Arnt on mouse chromosome 3 at locus 47.9.

5' Untranslated Regions↗
PubMed1999

Cyclic expression of mRNA transcripts for connective tissue components in the mouse ovary.

In the ovary, differentiation of germinal cells into primordial follicles, functional ovulatory follicles and corpus luteum, all take place in a connective tissue matrix. We postulated that extracellular matrix (ECM) of the ovary participates actively in ovarian functions. To test this, the mRNA levels for several ECM components were determined in the mouse ovary at six distinct stages of the 4-day oestrous cycle. Northern analysis revealed statistically significant cyclic expression patterns for the mRNAs coding for type III, IV and VI collagens as well as for the small proteoglycan, biglycan, and for syndecan-1 and osteonectin. The cyclic changes observed in the mRNAs for these structural components exceeded those for matrix metalloproteinases (MMP)-2, -9 and -13, and for tissue inhibitors of matrix metalloproteinases (TIMP)-1, -2 and -3, where the changes were not statistically significant, despite their apparent role in ECM remodelling in the ovary. These observations support the hypothesis that cyclic changes in the production and degradation of ECM are part of normal ovarian function connected with follicular maturation, rupture and corpus luteum formation.

Animals↗
PubMed1999

Expression profiles of mRNAs for osteoblast and osteoclast proteins as indicators of bone loss in mouse immobilization osteopenia model.

An experimental mouse model for disuse osteopenia was developed using unilateral cast immobilization. Analysis of the distal femurs and proximal tibias by quantitative histomorphometry revealed significant osteopenia within 10-21 days of immobilization. At 3 weeks, bone loss was also demonstrated with peripheral quantitative computed tomography as diminished bone mineral content and as concomitant reduction in the cross-sectional moment of inertia. These structural and geometrical alterations resulted in decreased strength of the distal femurs tested by cantilever bending. Analysis of the underlying cellular and molecular mechanisms of bone loss revealed a rapid increase in bone resorption within 3 days of immobilization. The mRNA levels for cathepsin K, matrix metalloproteinase-9, and tartrate resistant acid phosphatase were all significantly increased during the 21-day immobilization period, but with different expression profiles. These increases were paralleled by an increased number of osteoclasts as measured by histomorphometry. By day 6 of immobilization, the balance of bone turnover was further shifted toward net bone loss as the mRNA levels for major bone components (type I collagen and osteocalcin) were decreased. In histomorphometric analysis this was observed as reduced rates of mineral apposition and bone formation after 10 days of immobilization. The results of this study demonstrate that immobilization has a dual negative effect on bone turnover involving both depressed bone formation and enhanced bone resorption.

Animals↗
PubMed1998

Type X collagen, a natural component of mouse articular cartilage: association with growth, aging, and osteoarthritis.

OBJECTIVE: To perform a systematic study on the production and deposition of type X collagen in developing, aging, and osteoarthritic (OA) mouse articular cartilage. METHODS: Immunohistochemistry was employed to define the distribution of type X collagen and Northern analyses to determine the messenger RNA levels as an indicator of the synthetic activity of the protein. RESULTS: Type X collagen was observed in the epiphyseal and articular cartilage of mouse knee joints throughout development and growth. Type X collagen deposition in the transitional zone of articular cartilage became evident toward cessation of growth, at the age of 2-3 months. The most intense staining for type X collagen was limited to the tidemark, the border between uncalcified and calcified cartilage. Northern analysis confirmed that the type X collagen gene is also transcribed by articular cartilage chondrocytes. Intense immunostaining was observed in the areas of OA lesions, specifically, at sites of osteophyte formation and surface fibrillation. Type X collagen deposition was also seen in degenerating menisci. CONCLUSION: This study demonstrates that type X collagen is a natural component of mouse articular cartilage throughout development, growth, and aging. This finding and the deposition of type X collagen at sites of OA lesions suggest that type X collagen may have a role in providing structural support for articular cartilage.

Aging↗
PubMed1998

Expression of type II and IX collagen isoforms during normal and pathological cartilage and eye development.

Cartilage collagens type II and type IX exist in two alternative forms which arise from alternative splicing and alternative use of promoters, respectively. In the present study we analyzed temporal and spatial expression patterns of the two isoforms of type II and type IX collagen transcripts as well as those of alpha2(IX) and alpha3(IX) collagen mRNAs in limb cartilages and eyes during mouse embryonic development. Northern and RNase protection assays revealed temporal coregulation of the two alternative isoforms in limbs, but not in the eye where no long form of alpha1(IX) collagen mRNA was detected. Although in situ hybridization of limbs revealed identical expression patterns of the long form of type II collagen and the short form of alpha1(IX) collagen mRNA in the perichondrium and periosteum of 14.5-18.5-day embryos, the patterns were distinctly different at day 12.5 of development: the long form of type II collagen mRNA was expressed throughout the developing cartilaginous anlage whereas the short form of alpha1(IX) collagen mRNA was expressed in the surrounding mesenchyme. Some differences were also detected in the temporal and spatial expression patterns between the alpha1(IX), alpha2(IX), and alpha3(IX) collagen mRNAs. In the eyes, alpha2(IX) collagen mRNA had highest expression levels at day 12.5, whereas alpha1(IX) and alpha3(IX) collagen mRNAs peaked later, at day 16.5. In the limbs, alpha1(IX) and alpha3(IX), but not alpha2(IX), collagen mRNAs were detected in periosteal cells after 16.5 days of development. In transgenic Dell mice, harboring type II collagen transgenes with a small deletion mutation, expression of mutant mRNA affected neither the alternative splicing of wild-type or mutant transcripts nor the ratio of the two alternative forms of the alpha1(IX) collagen mRNA. Despite some distinct similarities, the two alternative forms of type II and type IX collagen must, therefore, be under differential control during mouse development.

Animals↗