Smad3 Regulates Tendon Matrix Organization and Binds Key Tendon Transcription Factors We Have Nothing to Disclose Current Challe

5/10/2013

Smad3 Regulates Tendon Matrix Organization and Binds We have nothing to disclose Key Tendon Transcription Factors

Ellora Berthet, Carol Chen, Kristin Butcher, Richard A. Schneider, Tamara Alliston, Mohana Amirtharajah

TGF signaling in tendon Current challenges to tendon repair β development and repair • Flexor tendon injury remains a significant problem TGFβ • Repair complicated by adhesion and re-rupture TβRI TβRII • “Biologic” Solution Pryce et al. Dev. 2009 • Limited knowledge of pathways of normal tendon development Smad3 ?? Katzel et al. JOR 2011

Differentiation Matrix Production Injury & Repair

How can we apply a molecular understanding of tendon development to improve tendon healing? Tendon Progenitors Tenocytes Tenocytes

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Matrix production is regulated by Smad3 is essential for the formation tissue specific transcription factors of normal tendon architecture

H & E SHG Scx Mkx WT

Collagen1 Collagen1

Tenomodulin Tenomodulin

Léjard et al. JBC 2007 Liu et al. Molec Cell Bio 2010 -/-

Shukunami et al. Dev Bio 2006 Angle(°) Dispersion

Mkx -/- Smad3 WT

-/- -/- WT Smad3 Scx

Murchison et al. Dev 2007

Smad3 is required for normal matrix Smad3 is required for normal gene protein expression in tendon expression in tendon

Col1 Tnc IgG WT -/- Smad3

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Smad3 binds the critical tendon Smad3 modulates the activity of transcription factors Scx and Mkx tissue specific transcription factors

- + + + Smad3-HA + - + + Scx-HA-FLAG α-Smad3 Smad3 Smad3 IP: FLAG HA Smad3 α-Scx Scx-HA ??? Scx ? HA Smad3 α-Smad3 Smad3 Flag Scx/Mkx Collagen I WCE α-Scx Scx-HA Tendon

CBP HDAC4/5 Smad3 Smad3 X Sox9 Collagen II Runx2 Osteocalcin Cartilage Bone

Smad3 binds the critical tendon transcription factors Scx and Mkx Conclusions

- + + + Smad3-FLAG • Smad3 is a critical + - + + Mkx-Myc TGFβ Mkx-Myc regulator of tendon α-Myc My Mkx IgG c formation IP: FLAG Smad3

TβRI Smad3 TβRII α-Smad3 Flag • Smad3 regulates gene Mkx-Myc and protein expression WCE α-Myc in mature tendon α-Smad3 Smad3 Smad3 Smad3 • Smad3 can bind Mkx Scx Scleraxis and Mohawk Collagen1 Tenascin-C

Matrix Production

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Acknowledgements

• Mohana Amirtharajah • Tamara Alliston • Richard Schneider • Carol Chen • Kristin Butcher • Alliston Lab

• Funding: – American Society for Surgery of the Hand – NIH NIDCR – UCSF Department of Orthopedic Surgery