Runx2 expression and action in chondrocytes are regulated by retinoid signaling and parathyroid hormone-related peptide (PTHrP)

Iwamoto, Masahiro; Kitagaki, Jirouta; Tamamura, Yoshihiro; Gentili, Chiara; Koyama, Eiki; Enomoto, Hirayuki; Komori, Toshihisa; Pacifici, Maurizio; Enomoto‐Iwamoto, Motomi

doi:10.1053/joca.2002.0860

Cited by 75 publications

(72 citation statements)

References 40 publications

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“…The gene was then isolated from the pBluescript vector by digestion with ClaI and NotI and ligated into the RCASBP(B) L-14 or L-44 vector in the correct orientation. [25] EGFP-actin was removed from pEGFP-Actin vector (Clontech Laboratories Inc., Mountain View, CA) by digestion with NheI and BamHI and inserted into RCASBP(B) vector. RCAS replication competent viral vectors encoding GFP, constitutively active (CA)-or dominant negative (DN)-Rac-1, CA-RhoA, CA-Cdc42, GFP-Rac-1, GFPCdc42, GFP-RhoA, or EGFP-actin were transfected into DF-1 cells (ATCC).…”

Section: Rcas Virus Construction and Infectionmentioning

confidence: 99%

Small GTPase protein Rac-1 is activated with maturation and regulates cell morphology and function in chondrocytes

Kerr

Otani

Koyama

et al. 2008

Experimental Cell Research

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During maturation, chondrocytes undergo changes in morphology, matrix production, and gene expression; however, it remains unclear whether these are interrelated. In this study, we examined whether Rho GTPases were involved in these regulatory interplays. Levels of active Rho GTPases were assayed in immature and mature primary chondrocytes. We found that activation of Rac-1 and Cdc42 increased with maturation, whereas RhoA levels remained unchanged. GFP-tagged Rho GTPases tracked cellular localization. Rac-1 was enriched at the cell membrane where it co-localized with cortical actin, while RhoA and Cdc42 were cytoplasmic. To test the roles of Rac-1 in chondrocyte maturation, we force-expressed constitutively active or dominant negative forms of Rac-1 and assessed phenotypic consequences in primary chondrocytes. Activated Rac-1 expression induced chondrocyte enlargement and increased matrix metalloproteinase expression, which are characteristic of mature chondrocytes. Conversely, Rac-1 inactivation diminished adhesion, decreased alkaline phosphatase activity, and stimulated functions typical of immature chondrocytes. Exposure to a pro-maturation factor, Wnt3A, induced a flattened and enlarged morphology accompanied by peripheral Rac-1 rearrangement. Wnt3A stimulated Tiam1 expression and Rac-1 activation, while DN-Rac-1 inhibited Wnt3A-induced cell spreading. Our data provide strong evidence that Rac-1 coordinates changes in chondrocyte phenotype and function and stimulates the maturation process essential for skeletal development.

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Section: Rcas Virus Construction and Infectionmentioning

confidence: 99%

Small GTPase protein Rac-1 is activated with maturation and regulates cell morphology and function in chondrocytes

Kerr

Otani

Koyama

et al. 2008

Experimental Cell Research

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“…any of several levels of regulation, including splice variation, ubiquitination, acetylation, and phosphorylation, as well as functional control through various DNA binding partners and inhibitors (reviewed in Franceschi and Xiao, 2003;Iwamoto et al, 2003;Bae and Lee, 2005;Lengner et al, 2005;Goldring et al, 2006).…”

Section: Runx2 In Larval Xenopus 1651mentioning

confidence: 99%

“…Studies in mouse and chicken have shown Runx2 mRNA to be transcriptionally active in the early cartilaginous skeleton (Inada et al, 1999;Enomoto et al, 2000Enomoto et al, , 2004EnomotoIwamoto et al, 2001;Iwamoto et al, 2003;Eames et al, 2004). However, neither species requires the gene product to be functional during early cartilage formation.…”

Section: The Evolution Of Cartilage Differentiationmentioning

confidence: 99%

“…In amniotes, Runx2 mRNA is present in mesenchymal precursors of osteoblasts and in those chondrocytes fated to be replaced by bone (Inada et al, 1999;Enomoto et al, 2000;Enomoto-Iwamoto et al, 2001;Iwamoto et al, 2003;Eames et al, 2004). Its early expression in chondrocytes does not appear to have any functional role until later stages of cartilage hypertrophy and osteogenesis (Kim et al, 1999;Ueta et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

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Runx2 is essential for larval hyobranchial cartilage formation in Xenopus laevis

Kerney

Gross

Howard

2007

Developmental Dynamics

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The vertebrate transcription factor protein Runx2 is regarded as a "master regulator" of bone formation due to the dramatic loss of the osseous skeleton in the mouse homozygous knockout. However, Runx2 mRNA also is expressed in the pre-hypertrophic cartilaginous skeleton of the mouse and chicken, where its developmental function is largely unknown. Several tiers of Runx2 regulation exist in the mouse, any of which may account for its seeming biological inactivity during early stages of skeletogenesis. Unlike mouse and chicken, zebrafish require Runx2 function in early cartilage differentiation. The present study reveals that the earlier functional role of Runx2 in cartilage differentiation is shared between zebrafish and Xenopus. A combination of morpholino oligonucleotide injections and neural crest transplants indicate that Runx2 is involved in differentiation of the cartilaginous hyobranchial skeleton in the frog, Xenopus laevis. Additionally, in situ hybridizations show runx2 mRNA expression in mesenchymal precursors of the cartilaginous skull, which reveals the earliest pre-patterning of these cartilages described to date. The early distribution of runx2 resolves the homology of the larval suprarostral plate, which is one of the oldest controversies of anuran skull development. Together these data reveal a shift in Runx2 protein function during vertebrate evolution towards its exclusive roles in cartilage hypertrophy and bone differentiation within the amniote lineage. Developmental Dynamics 236:1650 -1662, 2007.

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“…Phenotypic changes associated with chondrocyte hypertrophy are reported in articular chondrocytes in the context of osteoarthritis (OA). Here we report that isolated DZC have a larger cell diameter than SZC, as well as higher expression levels of ALP, and Runx2, a transcription factor necessary for chondrocyte hypertrophy and endochondral ossification (Enomoto et al, 2000;Enomoto-Iwamoto et al, 2001;Iwamoto et al, 2003;Otto et al, 1997). Overexpression of BMP2 or -7 increased cell diameter while Noggin decreased it, indicating that BMP activity was important for DZC hypertrophy.…”

Section: Bmps and Articular Chondrocyte Hypertrophymentioning

confidence: 79%

Differences in matrix accumulation and hypertrophy in superficial and deep zone chondrocytes are controlled by bone morphogenetic protein

et al. 2007

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Despite the knowledge that superficial zone chondrocytes (SZC, located within 100 μm of the articular surface) and deep zone chondrocytes (DZC, located near the calcified zone) have distinct phenotypes, previous studies on bone morphogenetic proteins (BMPs) have not differentiated its effects on SZC versus DZC. Using a pellet culture model we have compared phenotype, morphology and matrix accumulation in SZC and DZC with or without adenovirus-mediated overexpression of BMP-2 or -7 or the BMP antagonist Noggin. Greater accumulation of proteoglycan (PG)-rich matrix in the untreated DZC was associated with a hypertrophic phenotype with large cell diameters and high gene expression levels of runt-related transcription factor-2 (Runx2) as well as higher endogenous BMP activity. Noggin overexpression decreased matrix accumulation and cell diameters in SZC and DZC, confirming a role for endogenous BMP in both processes. In DZC, overexpression of either BMP2 or -7 increased cell diameter without increasing PG-rich matrix accumulation. In contrast, in SZC, BMP overexpression increased matrix accumulation and type II collagen gene expression without increasing cell diameter. These data indicate that differences in endogenous BMP activity level and responsiveness to BMPs define, in part, the differences between the SZC and DZC phenotype. They also suggest that SZC may be a more appropriate target for BMP therapy than DZC.

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Runx2 expression and action in chondrocytes are regulated by retinoid signaling and parathyroid hormone-related peptide (PTHrP)

Cited by 75 publications

References 40 publications

Small GTPase protein Rac-1 is activated with maturation and regulates cell morphology and function in chondrocytes

Small GTPase protein Rac-1 is activated with maturation and regulates cell morphology and function in chondrocytes

Runx2 is essential for larval hyobranchial cartilage formation in Xenopus laevis

Differences in matrix accumulation and hypertrophy in superficial and deep zone chondrocytes are controlled by bone morphogenetic protein

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