Abstract 2310: Loss of 14-3-3zeta attenuates miR-126 expression and results in neonatal lethality
Authors: Joshi Sonali , Yang Jun , Wang Qingfei , Li Ping , Wang Hai , Pickering Brian , Xiong Yan , Parker-Thornburg Jan , Behringer Richard , Yu Dihua 
Published: August 2015

Abstract
The 14-3-3zeta protein, a member of the 14-3-3 family regulates multiple cellular processes during development and genomic amplification of 14-3-3zeta is observed in multiple cancers. To dissect the in vivo function of 14-3-3zeta in development and in cancer, we generated a 14-3-3zeta knockout (14-3-3zeta-/-) mouse model. Targeted deletion of 14-3-3zeta in the C57Bl/6 murine genetic background led to neonatal lethality due to respiratory distress and could be rescued by out-breeding to the CD-1 or backcrossing to the FVB/NJ congenic background. Hematoxylin and eosin (H&E) staining performed on lung sections of 18.5 days post conception embryos showed that 14-3-3zeta-/- lungs lacked saccular structures and exhibited increased mesenchymal compartments with thickened saccular septae indicating that the lung development of 14-3-3zeta-/- mice is arrested at the pseudoglandular stage. Interestingly, we found that the blood vessels in the lungs of the 14-3-3zeta-/- mice were not integrated and were surrounded by leukocyte aggregates compared with their wild-type counterparts. Immuno-histochemistry studies revealed no significant difference in pneumocyte proliferation or pneumocyte differentiation. The expression of miR-126, a miRNA known to regulate lung vascular integrity was down-regulated in the lungs of the 14-3-3zeta-/- embryos in the C57Bl/6 background as compared to their wild-type counterparts. Mir-126 was also down-regulated in endothelial cells stably expressing 14-3-3zeta targeting shRNA. Loss of 14-3-3zeta in endothelial cells inhibited the angiogenic capability of the endothelial cells as determined by both trans-well migration assays and tube formation assays and these defects could be rescued by re-expressing miR-126. Mechanistically, loss of 14-3-3zeta was found to suppress Erk1/2 phosphorylation resulting in attenuated binding of the transcription factor Ets2 on the miR-126 promoter ultimately resulting in reduced expression of miR-126. Collectively, our data demonstrates that miR-126 is an important angiogenesis regulator that functions downstream of 14-3-3zeta and downregulation of miR-126 plays a critical role in 14-3-3zeta-loss induced defects in lung vasculature observed in a the C57Bl/6 background. Targeting of 14-3-3zeta in various cancers can exhibit anti-tumor activity and our results suggest that identifying the genes that contributed to 14-3-3zeta mediated lethality in the C57Bl/6 mouse strain may provide insights on predicting patients’ response to anti-14-3-3zeta therapy and optimizing personalized therapy in the future.
Citation Format: Sonali Joshi, Jun Yang, Qingfei Wang, Ping Li, Hai Wang, Brian Pickering, Yan Xiong, Jan Parker-Thornburg, Richard Behringer, Dihua Yu. Loss of 14-3-3zeta attenuates miR-126 expression and results in neonatal lethality. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2310. doi:10.1158/1538-7445.AM2015-2310