TGF- and Chondrocytes TGF- Dependent Repression of MMP13 in - - PowerPoint PPT Presentation

5/10/2013 1

TGF-β Dependent Repression of MMP13 in Chondrocytes Via a Smad3 and Runx2 Dependent Pathway

Daniel Thuillier, M.D.

TGF-β and Chondrocytes

• Well established role in chondrocyte

differentiation, maturation, maintenance of resting state

• Aberrant TGF-β signaling associated with

Osteoarthritis

• Experimentally ? Dual Role on chondrocytes

– ?Protective Decreased MMP-13 Expression – ?Deleterious Increased MMP-13 Expression

TGF-β: Two Pathways

MMP-13 MMP-13

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Therefore, we hypothesized that TGF-β inhibits Runx2-inducible MMP13 expression and terminal chondrocyte differentiation through Smad3-mediated repression of Runx2. We Know… TGF-β inhibits terminal osteoblast differentiation via a Smad3 and Runx2 dependent pathway

Chondrocyte Intrinsic Smad3

ColII-Cre;Smad3fl/fl MIce

• Can selectively knock out

Smad3 in cells that are expressing Collagen II (i.e. Articular Cartilage Cells)

• Allows for investigation of

Chondrocyte Intrinsic role

• f Smad3

A

0.0 0.5 1.0 1.5 Relative Smad3 mRNA Expression Smad3 fl/fl Col2-Cre;Smad3 fl/fl

B C

IgG

D

P14 P60 P90 Smad3fl/fl Col2-Cre; Smad3fl/fl

*

Col2-Cre;Smad3fl/fl Smad3fl/fl Smad3fl/fl Col2-Cre; Smad3fl/fl

E

Smad3fl/fl Col2-Cre;Smad3fl/fl 2 4 6 8 Modified …

F

articular cartilage growth plate

Figure 1 *

Chrondrocyte-intrinsic Smad3 is required to maintain growth plate and articular cartilage

Smad3fl/fl Col2-Cre;Smad3fl/fl

A B

Smad3fl/fl Col2-Cre;Smad3fl/fl

C D F G H

Col2 VDIPEN GPQG MMP-13 IgG Agn Pre-immune 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 Col2 Relative mRNA Expression Smad3fl/fl Col2-Cre;Smad3fl/fl 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 Agn Relative mRNA Expression Smad3fl/fl Col2-Cre;Smad3fl/fl

E

Molecular composition of growth plate and articular cartilage is disrupted in Col2-Cre;Smad3fl/fl mice

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TGF-β: Two Pathways

MMP-13 MMP-13

TGF-β exposure in cultured primary chondrocytes and ATDC5 cells show both repression and induction of MMP-13 expression in a time-dependent manner TGF-β mediated repression and induction of MMP-13 is dependent upon Runx2

ATDC5 ColII-Cre; Smad3fl/fl

TGF-β mediated repression of MMP-13 is dependent upon Smad3 in both ATDC5s and primary chondrocytes

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Summary

• TGF-β – Dual Role in Chondrocytes both

protective and deleterious

– Can Repress MMP-13 via Smad3 and Runx2

Thank You

• Tamara Alliston
• Carol Chen
• Emily Chin