Research On The Physiological Function And Mechanism Of Ubiquitin Ligase NEDL2

The E3 ubiquitin ligases are the major components of the ubiquitin-proteasome system in eukaryote cells and they determine the substrate specificity. Uncovering new functions of the E3 ubiquitin ligases is a hotspot in the E3 research field. According to the structural character, the E3 ubiquitin ligases are classified two types: RING-type ligases and HECT-type ligases. NEDL1(Nedd4-like ubiquitin ligase 1) and NEDL2(Nedd4-like ubiquitin ligase 2) belong to the Nedd4 family of HECT-type ligases. Their physiological functions and ubiquitination substrates still remain unknown. Recently, we established NEDL1 and NEDL2 gene knockout mice model. We strikingly found that NEDL2 deficiency resulted in the lethality within perinatal day 14, which indicated the critical role of NEDL2 during mouse early development, while NEDL1 knockout mice can grow normally until adult. Moreover, 100% of the NEDL2-deficient mice died with flatulence in enteric tract and about 33% of the NEDL2-deficient mice died with obvious hydronephrosis. Further results suggested that NEDL2 deletion caused severe defective development of the enteric nervous system.The ENS(enteric nervous system) is the largest part of the PNS(peripheral nervous system), and it plays an important role in maintenance of organism homeostasis. HSCR(Hirschsprung disease) is the well known disease for lacking enteric neurons and is characterized by severe constipation and distended abdomen. Previous studies have demonstrated that GDNF-RET signaling pathway plays important roles during ENS and kidney development. Kidney is also critical in maintenance of organism homeostasis for its important roles in water and acid-base balance. Abnormal development of Kidney also leads to a series of diseases, such as nephritis.This study indicated that NEDL2 is a positive regulator during ENS and kidney development. NEDL2 gene knockout causes myenteric neuronal hypoplasia and suppression of GDNF-AKT signaling activity. Moreover, we found that mutant kidney showed severe dysplasia with hydronephrosis and number of glomerular in the mutant kidneys reduced.Together, in this project we analyzed the phenotypes of NEDL2 knockout mice, and explored the relationship between NEDL2 and the GDNF-RET signaling pathway, which has been demonstrated as the most important pathway during ENS and kidney development. Here, we show that NEDL2 plays an essential and positive physiological role in regulating ENS development and GDNF-RET signaling. These ?ndings unveil the physiological function of NEDL2 in vivo.