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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.

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Related in: MedlinePlus

Ltbp-3– mouse. (A) Detection of Ltbp-3 mRNA in total lung RNA by Northern blot hybridization. (Top) Northern blot hybridization. +/+, Wild-type; −/−, Ltbp-3– animal. (Bottom) ethidium bromide image of RNA before transfer. (B) X-ray radiography of 2-mo-old wild-type and Ltbp-3– mice.
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fig2: Ltbp-3– mouse. (A) Detection of Ltbp-3 mRNA in total lung RNA by Northern blot hybridization. (Top) Northern blot hybridization. +/+, Wild-type; −/−, Ltbp-3– animal. (Bottom) ethidium bromide image of RNA before transfer. (B) X-ray radiography of 2-mo-old wild-type and Ltbp-3– mice.

Mentions: Ltbp-3– mice were produced by gene targeting using a targeting vector to replace two exons containing a nonunit number of codons (Joyner, 1995), including bases 278–807 of the ORF with the neor selectable marker (see online supplemental material, available at http://www.jcb.org/cgi/content/full/200111080/DC1, for details). These two exons code for the first EGF-like repeat, the pro-gly–rich region, and the beginning of the first 8-cys domain (Fig. 1). This deletion causes a frameshift in the ORF and premature termination of translation. Three clones (17, 22, and 25) with homologous recombination in the Ltbp-3 gene were detected by Southern blot analysis (unpublished data), and two clones were used to produce chimeric animals. Ltbp-3– animals were obtained by crossing heterozygous progeny of chimeric mice. Northern blot hybridization of lung RNA from animals with a probe mapping 3′ from the deleted region showed the absence of the Ltbp-3 transcript (Fig. 2 A). Therefore, we concluded that these mice were effectively Ltbp-3– animals. Ltbp-3– mice were born in the expected Mendelian ratio with no apparent defects. By day 10, animals displayed a rounded head and shortened snout. X-ray radiography of 2-mo-old mutant mice revealed a domed skull, abnormal apposition of the upper and lower incisors, and curvature of the cervical and thoracic vertebrae (thoracic kyphosis) (Fig. 2 B).


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)

Ltbp-3– mouse. (A) Detection of Ltbp-3 mRNA in total lung RNA by Northern blot hybridization. (Top) Northern blot hybridization. +/+, Wild-type; −/−, Ltbp-3– animal. (Bottom) ethidium bromide image of RNA before transfer. (B) X-ray radiography of 2-mo-old wild-type and Ltbp-3– mice.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2199217&req=5

fig2: Ltbp-3– mouse. (A) Detection of Ltbp-3 mRNA in total lung RNA by Northern blot hybridization. (Top) Northern blot hybridization. +/+, Wild-type; −/−, Ltbp-3– animal. (Bottom) ethidium bromide image of RNA before transfer. (B) X-ray radiography of 2-mo-old wild-type and Ltbp-3– mice.
Mentions: Ltbp-3– mice were produced by gene targeting using a targeting vector to replace two exons containing a nonunit number of codons (Joyner, 1995), including bases 278–807 of the ORF with the neor selectable marker (see online supplemental material, available at http://www.jcb.org/cgi/content/full/200111080/DC1, for details). These two exons code for the first EGF-like repeat, the pro-gly–rich region, and the beginning of the first 8-cys domain (Fig. 1). This deletion causes a frameshift in the ORF and premature termination of translation. Three clones (17, 22, and 25) with homologous recombination in the Ltbp-3 gene were detected by Southern blot analysis (unpublished data), and two clones were used to produce chimeric animals. Ltbp-3– animals were obtained by crossing heterozygous progeny of chimeric mice. Northern blot hybridization of lung RNA from animals with a probe mapping 3′ from the deleted region showed the absence of the Ltbp-3 transcript (Fig. 2 A). Therefore, we concluded that these mice were effectively Ltbp-3– animals. Ltbp-3– mice were born in the expected Mendelian ratio with no apparent defects. By day 10, animals displayed a rounded head and shortened snout. X-ray radiography of 2-mo-old mutant mice revealed a domed skull, abnormal apposition of the upper and lower incisors, and curvature of the cervical and thoracic vertebrae (thoracic kyphosis) (Fig. 2 B).

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