WTAP regulates stem cells via TRAF6 to maintain planarian homeostasis and regeneration

WTAP, a highly conserved Wilms' tumor 1 interacting protein, is involved in a variety of biological processes. However, functional studies of WTAP in planarians have not been reported. In this study, we examined the spatiotemporal expression pattern of planarian DjWTAP and investigated its functions in planarians regeneration and homeostasis. Knocking-down DjWTAP resulted in severe morphological defects leading to lethality within 20 days. Silencing DjWTAP promoted the proliferation of PiwiA+ cells but impaired the lineage differentiation of epidermal, neural, digestive, and excretory cell types, suggesting a critical role for DjWTAP in stem cell self -renewal and differentiation in planarian. To further investigate the mechanisms underlying the defective dif-ferentiation, RNA-seq was employed to determine the transcriptomic alterations upon DjWTAP RNA interference. Histone 4 (H4), Histone-lysine N-methyltransferase-SETMAR like, and TNF receptor-associated factor 6 (TRAF6), were significantly upregulated in response to DjWTAP RNAi. Knocking-down TRAF6 largely rescued the defective tissue homeostasis and regeneration resulted from DjWTAP knockdown in planarians, suggesting that DjWTAP maintains planarian regeneration and homeostasis via TRAF6.

Automated summary

In this study, we investigated the expression pattern and functions of the conserved WTAP gene in planarians. Knocking down WTAP resulted in severe morphological defects and lethality within 20 days. Silencing WTAP promoted the proliferation of PiwiA+ cells but impaired the differentiation of various cell types. RNA-seq analysis revealed upregulation of H4, Histone-lysine N-methyltransferase-SETMAR like, and TNF receptor-associated factor 6 (TRAF6) upon WTAP knockdown. Knocking down TRAF6 partially rescued the tissue homeostasis and regeneration defects, suggesting that WTAP maintains planarian regeneration and homeostasis via TRAF6.