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Bone abnormalities in latent TGF-[beta] binding protein (Ltbp)-3- mice indicate a role for Ltbp-3 in modulating TGF-[beta] bioavailability.

Dabovic B, Chen Y, Colarossi C, Obata H, Zambuto L, Perle MA, Rifkin DB - J. Cell Biol. (2002)

Bottom Line: Between 6 and 9 mo of age, mutant animals also develop osteosclerosis and osteoarthritis.The pathological changes of the Ltbp-3- mice are consistent with perturbed TGF-beta signaling in the skull and long bones.Moreover, the results provide the first in vivo indication for a role of LTBP in modulating TGF-beta bioavailability.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA. dabovb01@med.nyu.edu

ABSTRACT
The TGF-betas are multifunctional proteins whose activities are believed to be controlled by interaction with the latent TGF-beta binding proteins (LTBPs). In spite of substantial effort, the precise in vivo significance of this interaction remains unknown. To examine the role of the Ltbp-3, we made an Ltbp-3- mutation in the mouse by gene targeting. Homozygous mutant animals develop cranio-facial malformations by day 10. At 2 mo, there is a pronounced rounding of the cranial vault, extension of the mandible beyond the maxilla, and kyphosis. Histological examination of the skulls from animals revealed ossification of the synchondroses within 2 wk of birth, in contrast to the wild-type synchondroses, which never ossify. Between 6 and 9 mo of age, mutant animals also develop osteosclerosis and osteoarthritis. The pathological changes of the Ltbp-3- mice are consistent with perturbed TGF-beta signaling in the skull and long bones. These observations give support to the notion that LTBP-3 is important for the control of TGF-beta action. Moreover, the results provide the first in vivo indication for a role of LTBP in modulating TGF-beta bioavailability.

Show MeSH

Related in: MedlinePlus

The histological changes in basooccipital–basosphenoid synchondroses in 1.5-d-old wild-type and Ltbp-3– animals. (A and B) Weingart hematoxylin, Safranin O and Fast green staining. (A) Wild-type. (B) Mutant. Wider zone of hypertrophic chondrocytes in the mutant synchondrosis compared to the wild-type indicates more extensive differentiation. Cartilage is stained red. h, hypertrophic chondrocyte zone; r, resting chondrocyte zone; p, proliferating chondrocyte zone; ph, prehypertrophic chondrocyte zone; (C and D) Immunostaining for collagen X. (C) Wild-type. (D) Mutant. (E and F) Immunostaining for collagen II. (E) Wild-type. (F) Mutant. (G and H) Masson's trichrome staining for bone. More advanced bone fronts (blue) are apparent in mutant (H) versus wild-type (G) synchondrosis. Arrows point to fronts of the cortical basooccipital and basosphenoid bones. (I and J). In situ hybridization for bone sialoprotein 1 (Bsp-1). (I) Wild-type. (J) Mutant. (K and L) In situ hybridization for Ihh. (K) Wild-type. (L) Mutant. The strong signal in the middle of the mutant mouse synchondrosis (L) suggests that these chondrocytes are already committed to hypertrophic differentiation. (M and N) In situ hybridization for PTH/PTHrP-R. Expression pattern is less defined in the mutant animal sample (N) compared to the wild-type (M), and the transcript is detected through the central region of the synchondrosis. The intensity of the signal is similar in wild-type and in Ltbp-3– samples. (O and P). In situ hybridization for PTHrP. In wild-type synchondroses (O) expression is apparent in proliferating chondrocytes and in lateral chondrocytes of the central region of the synchondrosis. The signal is absent in the resting chondrocytes in the center of synchondrosis. The intensity of the signal is decreased in Ltbp-3– synchondrosis (P).
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fig4: The histological changes in basooccipital–basosphenoid synchondroses in 1.5-d-old wild-type and Ltbp-3– animals. (A and B) Weingart hematoxylin, Safranin O and Fast green staining. (A) Wild-type. (B) Mutant. Wider zone of hypertrophic chondrocytes in the mutant synchondrosis compared to the wild-type indicates more extensive differentiation. Cartilage is stained red. h, hypertrophic chondrocyte zone; r, resting chondrocyte zone; p, proliferating chondrocyte zone; ph, prehypertrophic chondrocyte zone; (C and D) Immunostaining for collagen X. (C) Wild-type. (D) Mutant. (E and F) Immunostaining for collagen II. (E) Wild-type. (F) Mutant. (G and H) Masson's trichrome staining for bone. More advanced bone fronts (blue) are apparent in mutant (H) versus wild-type (G) synchondrosis. Arrows point to fronts of the cortical basooccipital and basosphenoid bones. (I and J). In situ hybridization for bone sialoprotein 1 (Bsp-1). (I) Wild-type. (J) Mutant. (K and L) In situ hybridization for Ihh. (K) Wild-type. (L) Mutant. The strong signal in the middle of the mutant mouse synchondrosis (L) suggests that these chondrocytes are already committed to hypertrophic differentiation. (M and N) In situ hybridization for PTH/PTHrP-R. Expression pattern is less defined in the mutant animal sample (N) compared to the wild-type (M), and the transcript is detected through the central region of the synchondrosis. The intensity of the signal is similar in wild-type and in Ltbp-3– samples. (O and P). In situ hybridization for PTHrP. In wild-type synchondroses (O) expression is apparent in proliferating chondrocytes and in lateral chondrocytes of the central region of the synchondrosis. The signal is absent in the resting chondrocytes in the center of synchondrosis. The intensity of the signal is decreased in Ltbp-3– synchondrosis (P).

Mentions: Histologically, a synchondrosis resembles two opposed growth plates with a common zone of resting chondrocytes and separate zones of proliferating and hypertrophic chondrocytes. (Fig. 4 A). The earliest histological changes in the skull base of Ltbp-3– animals were detected in the basooccipital–basosphenoid synchondrosis 1–2 d after birth. The overall structure of the synchondrosis was altered, as no distinguishable columns of proliferating chondrocytes were visible in the mutant synchondrosis (Fig. 4, compare A and B), and the zones of hypertrophic chondrocytes were wider. Collagen X, a marker for hypertrophic chondrocytes (Elima et al., 1993), was restricted to the ends of the synchondrosis in wild-type animals (Fig. 4 C), but was detected almost throughout the synchondrosis in Ltbp-3– animals (Fig. 4 D). In addition, collagen type II, a marker for nonhypertrophic chondrocytes (Swalla et al., 1988), was present in the central zone of wild-type synchondrosis, but was absent from that of Ltbp-3– animals (Fig. 4, E and F). The distance between the cortical bone fronts was smaller in the animals compared to wild-type littermates as visualized by Masson's trichrome staining, which stains bone blue (Fig. 4, G and H). The ectopic ossification in mutant synchondrosis was also clear from the expression of the bone sialoprotein (Bsp)-1 gene, an osteoblast specific marker (Bianco et al., 1991), in the cells surrounding the synchondrosis (Fig. 4, I and J). Although the basooccipital–basosphenoid synchondrosis was obliterated by 3–5 d after birth, the first changes in the basosphenoid–presphenoid synchondrosis in the animals were not seen until days 3–10 (unpublished data).


Bone abnormalities in latent TGF-[beta] binding protein (Ltbp)-3- mice indicate a role for Ltbp-3 in modulating TGF-[beta] bioavailability.

Dabovic B, Chen Y, Colarossi C, Obata H, Zambuto L, Perle MA, Rifkin DB - J. Cell Biol. (2002)

The histological changes in basooccipital–basosphenoid synchondroses in 1.5-d-old wild-type and Ltbp-3– animals. (A and B) Weingart hematoxylin, Safranin O and Fast green staining. (A) Wild-type. (B) Mutant. Wider zone of hypertrophic chondrocytes in the mutant synchondrosis compared to the wild-type indicates more extensive differentiation. Cartilage is stained red. h, hypertrophic chondrocyte zone; r, resting chondrocyte zone; p, proliferating chondrocyte zone; ph, prehypertrophic chondrocyte zone; (C and D) Immunostaining for collagen X. (C) Wild-type. (D) Mutant. (E and F) Immunostaining for collagen II. (E) Wild-type. (F) Mutant. (G and H) Masson's trichrome staining for bone. More advanced bone fronts (blue) are apparent in mutant (H) versus wild-type (G) synchondrosis. Arrows point to fronts of the cortical basooccipital and basosphenoid bones. (I and J). In situ hybridization for bone sialoprotein 1 (Bsp-1). (I) Wild-type. (J) Mutant. (K and L) In situ hybridization for Ihh. (K) Wild-type. (L) Mutant. The strong signal in the middle of the mutant mouse synchondrosis (L) suggests that these chondrocytes are already committed to hypertrophic differentiation. (M and N) In situ hybridization for PTH/PTHrP-R. Expression pattern is less defined in the mutant animal sample (N) compared to the wild-type (M), and the transcript is detected through the central region of the synchondrosis. The intensity of the signal is similar in wild-type and in Ltbp-3– samples. (O and P). In situ hybridization for PTHrP. In wild-type synchondroses (O) expression is apparent in proliferating chondrocytes and in lateral chondrocytes of the central region of the synchondrosis. The signal is absent in the resting chondrocytes in the center of synchondrosis. The intensity of the signal is decreased in Ltbp-3– synchondrosis (P).
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Related In: Results  -  Collection

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fig4: The histological changes in basooccipital–basosphenoid synchondroses in 1.5-d-old wild-type and Ltbp-3– animals. (A and B) Weingart hematoxylin, Safranin O and Fast green staining. (A) Wild-type. (B) Mutant. Wider zone of hypertrophic chondrocytes in the mutant synchondrosis compared to the wild-type indicates more extensive differentiation. Cartilage is stained red. h, hypertrophic chondrocyte zone; r, resting chondrocyte zone; p, proliferating chondrocyte zone; ph, prehypertrophic chondrocyte zone; (C and D) Immunostaining for collagen X. (C) Wild-type. (D) Mutant. (E and F) Immunostaining for collagen II. (E) Wild-type. (F) Mutant. (G and H) Masson's trichrome staining for bone. More advanced bone fronts (blue) are apparent in mutant (H) versus wild-type (G) synchondrosis. Arrows point to fronts of the cortical basooccipital and basosphenoid bones. (I and J). In situ hybridization for bone sialoprotein 1 (Bsp-1). (I) Wild-type. (J) Mutant. (K and L) In situ hybridization for Ihh. (K) Wild-type. (L) Mutant. The strong signal in the middle of the mutant mouse synchondrosis (L) suggests that these chondrocytes are already committed to hypertrophic differentiation. (M and N) In situ hybridization for PTH/PTHrP-R. Expression pattern is less defined in the mutant animal sample (N) compared to the wild-type (M), and the transcript is detected through the central region of the synchondrosis. The intensity of the signal is similar in wild-type and in Ltbp-3– samples. (O and P). In situ hybridization for PTHrP. In wild-type synchondroses (O) expression is apparent in proliferating chondrocytes and in lateral chondrocytes of the central region of the synchondrosis. The signal is absent in the resting chondrocytes in the center of synchondrosis. The intensity of the signal is decreased in Ltbp-3– synchondrosis (P).
Mentions: Histologically, a synchondrosis resembles two opposed growth plates with a common zone of resting chondrocytes and separate zones of proliferating and hypertrophic chondrocytes. (Fig. 4 A). The earliest histological changes in the skull base of Ltbp-3– animals were detected in the basooccipital–basosphenoid synchondrosis 1–2 d after birth. The overall structure of the synchondrosis was altered, as no distinguishable columns of proliferating chondrocytes were visible in the mutant synchondrosis (Fig. 4, compare A and B), and the zones of hypertrophic chondrocytes were wider. Collagen X, a marker for hypertrophic chondrocytes (Elima et al., 1993), was restricted to the ends of the synchondrosis in wild-type animals (Fig. 4 C), but was detected almost throughout the synchondrosis in Ltbp-3– animals (Fig. 4 D). In addition, collagen type II, a marker for nonhypertrophic chondrocytes (Swalla et al., 1988), was present in the central zone of wild-type synchondrosis, but was absent from that of Ltbp-3– animals (Fig. 4, E and F). The distance between the cortical bone fronts was smaller in the animals compared to wild-type littermates as visualized by Masson's trichrome staining, which stains bone blue (Fig. 4, G and H). The ectopic ossification in mutant synchondrosis was also clear from the expression of the bone sialoprotein (Bsp)-1 gene, an osteoblast specific marker (Bianco et al., 1991), in the cells surrounding the synchondrosis (Fig. 4, I and J). Although the basooccipital–basosphenoid synchondrosis was obliterated by 3–5 d after birth, the first changes in the basosphenoid–presphenoid synchondrosis in the animals were not seen until days 3–10 (unpublished data).

Bottom Line: Between 6 and 9 mo of age, mutant animals also develop osteosclerosis and osteoarthritis.The pathological changes of the Ltbp-3- mice are consistent with perturbed TGF-beta signaling in the skull and long bones.Moreover, the results provide the first in vivo indication for a role of LTBP in modulating TGF-beta bioavailability.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA. dabovb01@med.nyu.edu

ABSTRACT
The TGF-betas are multifunctional proteins whose activities are believed to be controlled by interaction with the latent TGF-beta binding proteins (LTBPs). In spite of substantial effort, the precise in vivo significance of this interaction remains unknown. To examine the role of the Ltbp-3, we made an Ltbp-3- mutation in the mouse by gene targeting. Homozygous mutant animals develop cranio-facial malformations by day 10. At 2 mo, there is a pronounced rounding of the cranial vault, extension of the mandible beyond the maxilla, and kyphosis. Histological examination of the skulls from animals revealed ossification of the synchondroses within 2 wk of birth, in contrast to the wild-type synchondroses, which never ossify. Between 6 and 9 mo of age, mutant animals also develop osteosclerosis and osteoarthritis. The pathological changes of the Ltbp-3- mice are consistent with perturbed TGF-beta signaling in the skull and long bones. These observations give support to the notion that LTBP-3 is important for the control of TGF-beta action. Moreover, the results provide the first in vivo indication for a role of LTBP in modulating TGF-beta bioavailability.

Show MeSH
Related in: MedlinePlus