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210 Syndecan-4/fgf-2/pkca signalling regulates vascular smooth muscle cell calcification via cross-talk with tgfb
  1. Samantha Borland1,
  2. Shona Borland1,
  3. Mark Morgan2,
  4. Sheila Francis3,
  5. Catherine Merry4,
  6. Ann Canfield1
  1. 1University of Manchester
  2. 2University of Liverpool
  3. 3University of Sheffield
  4. 4University of Nottingham


Vascular smooth muscle cells (VSMCs) were induced to mineralise with β-glycerophosphate (β-GP). Controls were cultured without β-GP. FGF-2 mRNA (~40-fold increase, P<0.001) and protein (~2-fold increase, P<0.05) expression are significantly increased in mineralising VSMCs. FGF-2 also localises to sites of calcification within human atherosclerotic plaques. The expression of syndecan-4, a heparan sulphate proteoglycan which acts as a co-receptor for FGF-2 signalling, is also increased in mineralising VSMCs (~5-fold, P<0.001) and co-localizes with FGF-2 in human calcified atherosclerotic plaques. Exogenous FGF-2 inhibits VSMC mineralisation (P<0.001) and this inhibition is reduced when syndecan-4 expression is knocked-down using siRNA.

Biochemical inhibition of FGFR signalling using a pan FGFR inhibitor (BGJ398) increases transforming growth factor-β1 (TGFβ1)-induced Smad2 phosphorylation in VSMCs. As TGF β1 increases mineral deposition by VSMCs (~2-fold, P<0.01), the relationship between FGF and TGFβ signalling in VSMC mineralisation was investigated. Inhibiting FGFR signalling using BGJ398 or knocking-down syndecan-4 expression in VSMCs using siRNA increases VSMC mineralisation (both P<0.001). These increases are prevented by inhibiting TGFÎ2 signalling with SB431542, suggesting cross-talk between FGF-2 and TGFÎ2 signalling is crucial for the regulation of VSMC mineralisation. Syndecan-4 can also regulate FGF-2 signalling via protein kinase Cα (PKCα) activation. Biochemical inhibition of PKCα activity using G6976, or knocking-down PKCα expression increases VSMC mineralisation (both P<0.05); this increase is also prevented with SB431542. Finally, the ability of FGF-2 to inhibit VSMC mineralisation is reduced when PKCα expression is knocked-down.

In conclusion, our study has identified that syndecan-4/FGF-2 signalling is up-regulated in mineralising VSMCs to reduce TGFÎ2 signalling and minimise further calcification. Syndecan-4 regulates FGF-2 signalling to prevent excessive mineralisation by (a) acting as a co-receptor for FGF-2 and inducing downstream signalling via FGFR and (b) interaction with PKα. The syndecan-4/FGF-2/TGFα signalling axis could therefore represent a new therapeutic target for vascular calcification.

  • FGF-2
  • Syndecan-4
  • Calcification

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