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. Author manuscript; available in PMC: 2009 Nov 28.
Published in final edited form as: Cell. 2008 Nov 28;135(5):825–837. doi: 10.1016/j.cell.2008.09.059

Figure 7. Genetic interaction between Lrp5 and serotonin.

Figure 7

(A) Bone histomorphometric analysis (vertebrae) of WT, Htr1b+/−, Tph1gut+/−, Htr1b+/−;Tph1gut+/−, Lrp5−/−, Lrp5−/−;Htr1b+/− and Lrp5−/−;Tph1gut+/− mice.

(B) Bone histomorphometric analysis (vertebrae) of WT, β-Catgut+/−, Tph1gut+/−;β-Catgut+/−, Lrp5+/− and Lrp5+/−;β-Catgut+/− mice.

(C) Serum serotonin levels and real-time PCR analysis of Tph1 expression in the gut of WT and β-Catgut+/− mice.

(D) Bone histomorphometric analysis (vertebrae) of WT, WT(Ovx), Tph1gut−/− and Tph1gut−/−(Ovx) mice.

(E) Model of the Lrp5-dependent regulation of bone formation. Lrp5 favors bone formation and bone mass accrual by inhibiting Tph1 expression and serotonin synthesis in enterochromaffin cells. Following its binding to Htr1b serotonin inhibits Creb expression and function, this results in a decrease in CycD1 expression and osteoblast proliferation.