P73 C-terminus is dispensable for multiciliogenesis

The p53 family transcriptional factor p73 plays a pivotal role in development. Ablation of p73 results in severe neurodevelopmental defects, chronic infections, inflammation and infertility. In addition to this, Trp73(--)mice display severe alteration in the ciliated epithelial lining and the full-lengthN-terminal isoform TAp73 has been implicated in the control of multiciliogenesis transcriptional program. With our recently generated Trp73(Delta 13/Delta 13)mouse model, we interrogate the physiological role of p73 C-terminal isoformsin vivo. Trp73(Delta 13/Delta 13)mice lack exon 13 in Trp73 gene, producing an ectopic switch from the C-terminal isoforms p73 alpha to p73 beta. Trp73(Delta 13/Delta 13)mice show a pattern of expression of TAp73 comparable to the wild-type littermates, indicating that the alpha to beta switch does not significantly alter the expression of the gene in this cell type. Moreover, Trp73(Delta 13/Delta 13)do not display any significant alteration in the airway ciliated epithelium, suggesting that in this context p73 beta can fully substitute the function of the longer isoform p73 alpha. Similarly, Trp73(Delta 13/Delta 13)ciliated epithelium of the brain ependyma also does appear defective. In this district however expression of TAp73 is not detectable, indicating that expression of the gene might be compensated by alternative mechanisms. Overall our work indicates that C-terminus p73 is dispensable for the multiciliogenesis program and suggests a possible tissue-specific effect of p73 alternative splicing.