Objective: Notch signaling has been implicated in the development of pulmonary arterial hypertension (PH) as reflected by increased expression of Notch member proteins that induce the proliferation of pulmonary arterial smooth muscle cells (PASMCs). Soluble Jagged1 (sJag1) has been shown to inhibit Notch signaling in vitro and in vivo; however, its capacity to suppress PH remains unknown.
Approach and results: Notch1, Notch3, Jagged1, and Herp2 protein were highly expressed in both the mouse model of hypoxia-induced PH and the rat model of monocrotaline-induced PH. By attenuation and reversal of multiple pathological processes that were associated with PH, adenoviral sJag1 transfection significantly reduced the proliferation and enhanced the apoptosis of PASMCs in PH, whereas vehicle had no effect. The sJag1 inhibitory effect on Notch activation is likely related to its interference with ligand-induced signaling. Importantly, the administration with adenoviral sJag1 improved the survival rate of PH rats. Furthermore, sJag1 can restore the PH-PASMCs phenotype from the dedifferentiated to the differentiated state, by giving a positive effect on the physical binding of myocardin to the CC(A/T)nGG (CArG)-containing regions of vascular smooth muscle cells-specific promoters.
Conclusions: Our results demonstrated that the potential therapeutic use of the sJag1 may not only inhibit the proliferation of PASMCs but also restore the PH-PASMCs phenotype from the dedifferentiated to the differentiated state through interference with Notch-Herp2 signaling.
Keywords: hypertension, pulmonary; phenotype; smooth muscle cells.