Limits...
Gelsolin deficiency blocks podosome assembly and produces increased bone mass and strength.

Chellaiah M, Kizer N, Silva M, Alvarez U, Kwiatkowski D, Hruska KA - J. Cell Biol. (2000)

Bottom Line: They failed to respond to the autocrine factor, OP, with stimulation of motility and bone resorption.Gelsolin deficiency was associated with normal skeletal development and endochondral bone growth.These observations demonstrate the critical role of gelsolin in podosome assembly, rapid cell movements, and signal transduction through the alpha(v)beta(3) integrin.

View Article: PubMed Central - PubMed

Affiliation: Renal Division, Department of Medicine, Barnes-Jewish Hospital, Washington University, St. Louis, Missouri 63110, USA.

ABSTRACT
Osteoclasts are unique cells that utilize podosomes instead of focal adhesions for matrix attachment and cytoskeletal remodeling during motility. We have shown that osteopontin (OP) binding to the alpha(v)beta(3) integrin of osteoclast podosomes stimulated cytoskeletal reorganization and bone resorption by activating a heteromultimeric signaling complex that includes gelsolin, pp(60c-src), and phosphatidylinositol 3'-kinase. Here we demonstrate that gelsolin deficiency blocks podosome assembly and alpha(v)beta(3)-stimulated signaling related to motility in gelsolin- mice. Gelsolin-deficient osteoclasts were hypomotile due to retarded remodeling of the actin cytoskeleton. They failed to respond to the autocrine factor, OP, with stimulation of motility and bone resorption. Gelsolin deficiency was associated with normal skeletal development and endochondral bone growth. However, gelsolin- mice had mildly abnormal epiphyseal structure, retained cartilage proteoglycans in metaphyseal trabeculae, and increased trabecular thickness. With age, the gelsolin-deficient mice expressed increased trabecular and cortical bone thickness producing mechanically stronger bones. These observations demonstrate the critical role of gelsolin in podosome assembly, rapid cell movements, and signal transduction through the alpha(v)beta(3) integrin.

Show MeSH

Related in: MedlinePlus

Histomorphometric analysis of proximal tibial sections of Gsn−/− and Gsn+/+ mice. Proximal tibial sections of bone isolated from 14-wk-old Gsn+/+ (A and B) and Gsn−/− (C and D) mice were stained for TRAP (A and C) or with toluidine blue (B and D). (A and C) TRAP staining. Numerous osteoclasts were visible in the primary spongiosa and on the surfaces of metaphyseal trabeculae in both +/+ (A) and −/− mice (C). The number of TRAP-positive osteoclasts below the growth plate in −/− mice tends to be increased, giving the appearance of a double row of cells as the trabeculae develop from the primary spongiosa (C). The trabecular bone volume in the metaphysis of the −/− mice was increased (shown by arrows; compare A and C; see Table ). (B and D) Toluidine blue staining. The metaphyseal trabeculae of −/− mice (D) had retained cartilage-derived proteoglycan.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2169374&req=5

Figure 10: Histomorphometric analysis of proximal tibial sections of Gsn−/− and Gsn+/+ mice. Proximal tibial sections of bone isolated from 14-wk-old Gsn+/+ (A and B) and Gsn−/− (C and D) mice were stained for TRAP (A and C) or with toluidine blue (B and D). (A and C) TRAP staining. Numerous osteoclasts were visible in the primary spongiosa and on the surfaces of metaphyseal trabeculae in both +/+ (A) and −/− mice (C). The number of TRAP-positive osteoclasts below the growth plate in −/− mice tends to be increased, giving the appearance of a double row of cells as the trabeculae develop from the primary spongiosa (C). The trabecular bone volume in the metaphysis of the −/− mice was increased (shown by arrows; compare A and C; see Table ). (B and D) Toluidine blue staining. The metaphyseal trabeculae of −/− mice (D) had retained cartilage-derived proteoglycan.

Mentions: To assess skeletal histomorphometry, mice were injected with calcein to label areas of bone mineralization on two occasions, and histomorphometry of nondecalcified and decalcified bone sections was performed as described in Materials and Methods. Bone sections were stained for cartilage proteoglycans with toluidine blue, and for TRAP to aid in detection of osteoclasts. As shown in Fig. 10, at 14 wk of age the chondrocytes of the epiphyseal growth plates were reduced in number, mildly disorganized, and the cartilage matrix was expanded. The bone trabeculae in the metaphyses below the primary spongiosa of Gsn−/− mice had retained cartilage proteoglycan detected by the toluidine blue stain. Furthermore, the metaphyseal trabeculae of Gsn−/− bones (Fig. 10A and Fig. C, arrowheads) were thicker as confirmed by formal histomorphometric measurements (Table ). Osteoclast numbers and osteoclast perimeters in the metaphyses tended to be higher in the bones from Gsn−/− mice, as shown in the sections stained for TRAP (Fig. 10 B). This increase was not statistically significant (Table ), but it may have been adaptive for the decreased bone resorption. The intensity of the TRAP stain did not differ between wild-type and mutant osteoclasts. The decrease in bone resorption of mutant mice was demonstrated by changes in eroded perimeters. The perimeters of eroded surfaces were significantly reduced in Gsn−/− mice (P < 0.05), demonstrating that osteoclast-mediated bone resorption was diminished.


Gelsolin deficiency blocks podosome assembly and produces increased bone mass and strength.

Chellaiah M, Kizer N, Silva M, Alvarez U, Kwiatkowski D, Hruska KA - J. Cell Biol. (2000)

Histomorphometric analysis of proximal tibial sections of Gsn−/− and Gsn+/+ mice. Proximal tibial sections of bone isolated from 14-wk-old Gsn+/+ (A and B) and Gsn−/− (C and D) mice were stained for TRAP (A and C) or with toluidine blue (B and D). (A and C) TRAP staining. Numerous osteoclasts were visible in the primary spongiosa and on the surfaces of metaphyseal trabeculae in both +/+ (A) and −/− mice (C). The number of TRAP-positive osteoclasts below the growth plate in −/− mice tends to be increased, giving the appearance of a double row of cells as the trabeculae develop from the primary spongiosa (C). The trabecular bone volume in the metaphysis of the −/− mice was increased (shown by arrows; compare A and C; see Table ). (B and D) Toluidine blue staining. The metaphyseal trabeculae of −/− mice (D) had retained cartilage-derived proteoglycan.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2169374&req=5

Figure 10: Histomorphometric analysis of proximal tibial sections of Gsn−/− and Gsn+/+ mice. Proximal tibial sections of bone isolated from 14-wk-old Gsn+/+ (A and B) and Gsn−/− (C and D) mice were stained for TRAP (A and C) or with toluidine blue (B and D). (A and C) TRAP staining. Numerous osteoclasts were visible in the primary spongiosa and on the surfaces of metaphyseal trabeculae in both +/+ (A) and −/− mice (C). The number of TRAP-positive osteoclasts below the growth plate in −/− mice tends to be increased, giving the appearance of a double row of cells as the trabeculae develop from the primary spongiosa (C). The trabecular bone volume in the metaphysis of the −/− mice was increased (shown by arrows; compare A and C; see Table ). (B and D) Toluidine blue staining. The metaphyseal trabeculae of −/− mice (D) had retained cartilage-derived proteoglycan.
Mentions: To assess skeletal histomorphometry, mice were injected with calcein to label areas of bone mineralization on two occasions, and histomorphometry of nondecalcified and decalcified bone sections was performed as described in Materials and Methods. Bone sections were stained for cartilage proteoglycans with toluidine blue, and for TRAP to aid in detection of osteoclasts. As shown in Fig. 10, at 14 wk of age the chondrocytes of the epiphyseal growth plates were reduced in number, mildly disorganized, and the cartilage matrix was expanded. The bone trabeculae in the metaphyses below the primary spongiosa of Gsn−/− mice had retained cartilage proteoglycan detected by the toluidine blue stain. Furthermore, the metaphyseal trabeculae of Gsn−/− bones (Fig. 10A and Fig. C, arrowheads) were thicker as confirmed by formal histomorphometric measurements (Table ). Osteoclast numbers and osteoclast perimeters in the metaphyses tended to be higher in the bones from Gsn−/− mice, as shown in the sections stained for TRAP (Fig. 10 B). This increase was not statistically significant (Table ), but it may have been adaptive for the decreased bone resorption. The intensity of the TRAP stain did not differ between wild-type and mutant osteoclasts. The decrease in bone resorption of mutant mice was demonstrated by changes in eroded perimeters. The perimeters of eroded surfaces were significantly reduced in Gsn−/− mice (P < 0.05), demonstrating that osteoclast-mediated bone resorption was diminished.

Bottom Line: They failed to respond to the autocrine factor, OP, with stimulation of motility and bone resorption.Gelsolin deficiency was associated with normal skeletal development and endochondral bone growth.These observations demonstrate the critical role of gelsolin in podosome assembly, rapid cell movements, and signal transduction through the alpha(v)beta(3) integrin.

View Article: PubMed Central - PubMed

Affiliation: Renal Division, Department of Medicine, Barnes-Jewish Hospital, Washington University, St. Louis, Missouri 63110, USA.

ABSTRACT
Osteoclasts are unique cells that utilize podosomes instead of focal adhesions for matrix attachment and cytoskeletal remodeling during motility. We have shown that osteopontin (OP) binding to the alpha(v)beta(3) integrin of osteoclast podosomes stimulated cytoskeletal reorganization and bone resorption by activating a heteromultimeric signaling complex that includes gelsolin, pp(60c-src), and phosphatidylinositol 3'-kinase. Here we demonstrate that gelsolin deficiency blocks podosome assembly and alpha(v)beta(3)-stimulated signaling related to motility in gelsolin- mice. Gelsolin-deficient osteoclasts were hypomotile due to retarded remodeling of the actin cytoskeleton. They failed to respond to the autocrine factor, OP, with stimulation of motility and bone resorption. Gelsolin deficiency was associated with normal skeletal development and endochondral bone growth. However, gelsolin- mice had mildly abnormal epiphyseal structure, retained cartilage proteoglycans in metaphyseal trabeculae, and increased trabecular thickness. With age, the gelsolin-deficient mice expressed increased trabecular and cortical bone thickness producing mechanically stronger bones. These observations demonstrate the critical role of gelsolin in podosome assembly, rapid cell movements, and signal transduction through the alpha(v)beta(3) integrin.

Show MeSH
Related in: MedlinePlus