Experimental Biology 2016 San Diego

  • Aanvrager: Mevrouw N.P. Tania

Experimental Biology 2016 congres van 2 tm 6 april 2016 te San Diego, USA. Tania N. Rijks Universiteit Groningen

Pulmonary arterial hypertension (PAH) is a progressive disease that is characterized by vascular remodeling and sustained vasoconstriction which consequently lead to high blood pressure in the pulmonary vasculature and right ventricle remodeling.
Altered bone morphogenetic protein (BMP) signaling has been implicated in the pathogenesis of PAH as well as in pulmonary vascular maturation. The endogenous BMP antagonist follistatin-like 1(Fstl1) is highly expressed in pulmonary vascular endothelium of the developing lung in mice, suggesting a role in pulmonary vessel formation. In this study, the role of Fstl1 in the maturation of the pulmonary vasculature was investigated using Tie2-cre mediated endothelial-specific Fstl1 knackout mice. To this end, Fstl1 fl/fl mice were bred with Fstl1WT/Ko Tie 2-cre mice to generate Fsti1KO/fl Tie2-cre mice and control littermates Fstl1WT/f1Tie 2-cre, Fstl1Ko/tl, and Fstl1WT/fl. Heart and lung tissue was collected from pups at 1and 3 weeks after birth. The percentage of actin-positive small vessels per total number of vessels was determined. The expression level of Fst11and BMP/Smad-regulated genes was determined in total RNA isolated from lungs using qPCR. Activatien of BMP signaling was investigated using western blot. In wildtype mice, the mRNA expression of Fstl1 was higher in lung tissue at 1 week than 3 weeks (p<O.OOS). In line with the idea that Fstl1is a BMP inhibitor, BMP signaling was more active at 3 weeks than 1week, reflected by the higher level of pSmad1/5/8 at 3 weeks than 1week. Moreover, the mRNA levels of the BMP/Smad-regulated genes JAG1(p<O.OS) and endothelin-1(p<O.OOS) were increased at 3 weeks compared to 1 week after birth. Endothelial-specific deletien of Fstl1 was postnatally lethal, approx. 70% of Fstl KO/fl ne 2-cre mice died at 3 weeks after birth. Though most were
found dead, some were found in respiratory distress prior to dying. In these mice, Fstl1 mRNA expressionwas reduced (p<0.01) compared to wildtype mice at 1week. Endothelial deletien of Fstl1 resulted in activatien of Smad1/5/8 signaling and increased BMP/Smad-regulated gene expression of JAG1 (p<O.OS), endoglin (p<O.OS), and endothelin-1 (p<O.OS) at 1 week. At 3 weeks, JAG1 was reduced (p<0.01) whereas endoglin and endothelin-1were unchanged. Furthermore, the percentage of actin-positive small pulmonary vessels was increased at 3 weeks old of Fstl1KO/fl ne 2-cre mice
campare to wildtype (p<O.OOS) whereas it was unaltered at 1week. Loss of endothelial Fstl1induces activatien of BMP-mediated gene expression and microvasculature remodeling, which presumably due to alteratien in endothelin-1expression.

This study was supported by a grant from the Netherlands Lung Foundation grant number: