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Expression of a truncated, kinase-defective TGF-beta type II receptor in mouse skeletal tissue promotes terminal chondrocyte differentiation and osteoarthritis.

Serra R, Johnson M, Filvaroff EH, LaBorde J, Sheehan DM, Derynck R, Moses HL - J. Cell Biol. (1997)

Bottom Line: Lower levels of DNIIR mRNA were detected in growth plate cartilage.It is thought to be involved in a feedback loop that signals through the periosteum/ perichondrium to inhibit cartilage differentiation.The data suggest that TGF-beta may be critical for multifaceted maintenance of synovial joints.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology and the Vanderbilt Cancer Center, Vanderbilt University, Nashville, Tennessee 37232, USA.

ABSTRACT
Members of the TGF-beta superfamily are important regulators of skeletal development. TGF-betas signal through heteromeric type I and type II receptor serine/threonine kinases. When over-expressed, a cytoplasmically truncated type II receptor can compete with the endogenous receptors for complex formation, thereby acting as a dominant-negative mutant (DNIIR). To determine the role of TGF-betas in the development and maintenance of the skeleton, we have generated transgenic mice (MT-DNIIR-4 and -27) that express the DNIIR in skeletal tissue. DNIIR mRNA expression was localized to the periosteum/perichondrium, syno-vium, and articular cartilage. Lower levels of DNIIR mRNA were detected in growth plate cartilage. Transgenic mice frequently showed bifurcation of the xiphoid process and sternum. They also developed progressive skeletal degeneration, resulting by 4 to 8 mo of age in kyphoscoliosis and stiff and torqued joints. The histology of affected joints strongly resembled human osteo-arthritis. The articular surface was replaced by bone or hypertrophic cartilage as judged by the expression of type X collagen, a marker of hypertrophic cartilage normally absent from articular cartilage. The synovium was hyperplastic, and cartilaginous metaplasia was observed in the joint space. We then tested the hypothesis that TGF-beta is required for normal differentiation of cartilage in vivo. By 4 and 8 wk of age, the level of type X collagen was increased in growth plate cartilage of transgenic mice relative to wild-type controls. Less proteoglycan staining was detected in the growth plate and articular cartilage matrix of transgenic mice. Mice that express DNIIR in skeletal tissue also demonstrated increased Indian hedgehog (IHH) expression. IHH is a secreted protein that is expressed in chondrocytes that are committed to becoming hypertrophic. It is thought to be involved in a feedback loop that signals through the periosteum/ perichondrium to inhibit cartilage differentiation. The data suggest that TGF-beta may be critical for multifaceted maintenance of synovial joints. Loss of responsiveness to TGF-beta promotes chondrocyte terminal differentiation and results in development of degenerative joint disease resembling osteoarthritis in humans.

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Expression of DNIIR mRNA in embryos. Sections of  12.5-d post-coital wild-type (A) and MTR-DNIIR transgenic (B)  embryos were hybridized to an 35S-labeled DNIIR riboprobe.  DNIIR nRNA expression was detected in the mesenchyme of the  thoracic body wall (A and B, arrow) in MT-DNIIR transgenic but  not wild-type embryos at the time the sternum begins to develop.  Toluidine blue–stained bright field (A and B) and dark field (A′  and B′) images are shown. Li, liver, Ht, heart. Bifurcated sternum  in 17.5-d post-coital MT-DNIIR-4 mice. Alizarin red/alcian blue-stained skeletal preparations of wild-type (C) and MT-DNIIR  transgenic (D) embryos at 17.5 d post coitus. Bar, 200 μm.
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Figure 5: Expression of DNIIR mRNA in embryos. Sections of 12.5-d post-coital wild-type (A) and MTR-DNIIR transgenic (B) embryos were hybridized to an 35S-labeled DNIIR riboprobe. DNIIR nRNA expression was detected in the mesenchyme of the thoracic body wall (A and B, arrow) in MT-DNIIR transgenic but not wild-type embryos at the time the sternum begins to develop. Toluidine blue–stained bright field (A and B) and dark field (A′ and B′) images are shown. Li, liver, Ht, heart. Bifurcated sternum in 17.5-d post-coital MT-DNIIR-4 mice. Alizarin red/alcian blue-stained skeletal preparations of wild-type (C) and MT-DNIIR transgenic (D) embryos at 17.5 d post coitus. Bar, 200 μm.

Mentions: To determine if skeletal defects were due to alterations in embryonic skeletal development, alizarin red S/alcian blue whole mount skeletal preparations from 17.5-d post-coital wild-type and MT-DNIIR mice were performed. Fusion of the sternum was incomplete in 64% (23/36) of MT-DNIIR mice (Fig. 5, C and D). The degree of sternal bifurcation varied. The most severe cases extended caudally from the fifth rib, and the least severe cases involved only the xiphoid process. Defects in the size or shape of the long bones or vertebrae were not detected in 17.5-d post-coital mice. Since sternal development and fusion occur between 12 and 15 d post-coitum, expression and localization of DNIIR mRNA were examined by in situ hybridization in 12.5-d post-coital MT-DNIIR embryos (Fig. 5). Sections of wild-type and transgenic embryos were hybridized to an 35S-labeled antisense DNIIR riboprobe. Expression was localized to the mesenchyme of the thoracic body wall in transgenic embryos (Fig. 5 B). There was no difference in DNIIR mRNA expression in MT-DNIIR embryos from mothers maintained on 25 mM ZnSO4 or tap water. No hybridization was detected in sections from wild-type embryos (Fig. 5 A) or in sections hybridized to an 35S-labeled sense riboprobe (data not shown). These data suggest expression of the DNIIR mRNA in the mesenchyme of the thoracic body wall during sternal development results in incomplete fusion of the sternum (Fig. 5 D). Since no other skeletal defects were detected in 17.5-d post-coital mice, and DNIIR mRNA in the embryo was limited to the thoracic body wall, the other defects observed in adult transgenic mice (Table I, Fig. 2) are probably not a secondary result of early developmental defects in patterning of the cartilage model.


Expression of a truncated, kinase-defective TGF-beta type II receptor in mouse skeletal tissue promotes terminal chondrocyte differentiation and osteoarthritis.

Serra R, Johnson M, Filvaroff EH, LaBorde J, Sheehan DM, Derynck R, Moses HL - J. Cell Biol. (1997)

Expression of DNIIR mRNA in embryos. Sections of  12.5-d post-coital wild-type (A) and MTR-DNIIR transgenic (B)  embryos were hybridized to an 35S-labeled DNIIR riboprobe.  DNIIR nRNA expression was detected in the mesenchyme of the  thoracic body wall (A and B, arrow) in MT-DNIIR transgenic but  not wild-type embryos at the time the sternum begins to develop.  Toluidine blue–stained bright field (A and B) and dark field (A′  and B′) images are shown. Li, liver, Ht, heart. Bifurcated sternum  in 17.5-d post-coital MT-DNIIR-4 mice. Alizarin red/alcian blue-stained skeletal preparations of wild-type (C) and MT-DNIIR  transgenic (D) embryos at 17.5 d post coitus. Bar, 200 μm.
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Figure 5: Expression of DNIIR mRNA in embryos. Sections of 12.5-d post-coital wild-type (A) and MTR-DNIIR transgenic (B) embryos were hybridized to an 35S-labeled DNIIR riboprobe. DNIIR nRNA expression was detected in the mesenchyme of the thoracic body wall (A and B, arrow) in MT-DNIIR transgenic but not wild-type embryos at the time the sternum begins to develop. Toluidine blue–stained bright field (A and B) and dark field (A′ and B′) images are shown. Li, liver, Ht, heart. Bifurcated sternum in 17.5-d post-coital MT-DNIIR-4 mice. Alizarin red/alcian blue-stained skeletal preparations of wild-type (C) and MT-DNIIR transgenic (D) embryos at 17.5 d post coitus. Bar, 200 μm.
Mentions: To determine if skeletal defects were due to alterations in embryonic skeletal development, alizarin red S/alcian blue whole mount skeletal preparations from 17.5-d post-coital wild-type and MT-DNIIR mice were performed. Fusion of the sternum was incomplete in 64% (23/36) of MT-DNIIR mice (Fig. 5, C and D). The degree of sternal bifurcation varied. The most severe cases extended caudally from the fifth rib, and the least severe cases involved only the xiphoid process. Defects in the size or shape of the long bones or vertebrae were not detected in 17.5-d post-coital mice. Since sternal development and fusion occur between 12 and 15 d post-coitum, expression and localization of DNIIR mRNA were examined by in situ hybridization in 12.5-d post-coital MT-DNIIR embryos (Fig. 5). Sections of wild-type and transgenic embryos were hybridized to an 35S-labeled antisense DNIIR riboprobe. Expression was localized to the mesenchyme of the thoracic body wall in transgenic embryos (Fig. 5 B). There was no difference in DNIIR mRNA expression in MT-DNIIR embryos from mothers maintained on 25 mM ZnSO4 or tap water. No hybridization was detected in sections from wild-type embryos (Fig. 5 A) or in sections hybridized to an 35S-labeled sense riboprobe (data not shown). These data suggest expression of the DNIIR mRNA in the mesenchyme of the thoracic body wall during sternal development results in incomplete fusion of the sternum (Fig. 5 D). Since no other skeletal defects were detected in 17.5-d post-coital mice, and DNIIR mRNA in the embryo was limited to the thoracic body wall, the other defects observed in adult transgenic mice (Table I, Fig. 2) are probably not a secondary result of early developmental defects in patterning of the cartilage model.

Bottom Line: Lower levels of DNIIR mRNA were detected in growth plate cartilage.It is thought to be involved in a feedback loop that signals through the periosteum/ perichondrium to inhibit cartilage differentiation.The data suggest that TGF-beta may be critical for multifaceted maintenance of synovial joints.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology and the Vanderbilt Cancer Center, Vanderbilt University, Nashville, Tennessee 37232, USA.

ABSTRACT
Members of the TGF-beta superfamily are important regulators of skeletal development. TGF-betas signal through heteromeric type I and type II receptor serine/threonine kinases. When over-expressed, a cytoplasmically truncated type II receptor can compete with the endogenous receptors for complex formation, thereby acting as a dominant-negative mutant (DNIIR). To determine the role of TGF-betas in the development and maintenance of the skeleton, we have generated transgenic mice (MT-DNIIR-4 and -27) that express the DNIIR in skeletal tissue. DNIIR mRNA expression was localized to the periosteum/perichondrium, syno-vium, and articular cartilage. Lower levels of DNIIR mRNA were detected in growth plate cartilage. Transgenic mice frequently showed bifurcation of the xiphoid process and sternum. They also developed progressive skeletal degeneration, resulting by 4 to 8 mo of age in kyphoscoliosis and stiff and torqued joints. The histology of affected joints strongly resembled human osteo-arthritis. The articular surface was replaced by bone or hypertrophic cartilage as judged by the expression of type X collagen, a marker of hypertrophic cartilage normally absent from articular cartilage. The synovium was hyperplastic, and cartilaginous metaplasia was observed in the joint space. We then tested the hypothesis that TGF-beta is required for normal differentiation of cartilage in vivo. By 4 and 8 wk of age, the level of type X collagen was increased in growth plate cartilage of transgenic mice relative to wild-type controls. Less proteoglycan staining was detected in the growth plate and articular cartilage matrix of transgenic mice. Mice that express DNIIR in skeletal tissue also demonstrated increased Indian hedgehog (IHH) expression. IHH is a secreted protein that is expressed in chondrocytes that are committed to becoming hypertrophic. It is thought to be involved in a feedback loop that signals through the periosteum/ perichondrium to inhibit cartilage differentiation. The data suggest that TGF-beta may be critical for multifaceted maintenance of synovial joints. Loss of responsiveness to TGF-beta promotes chondrocyte terminal differentiation and results in development of degenerative joint disease resembling osteoarthritis in humans.

Show MeSH
Related in: MedlinePlus