The tumor suppressor p53-related p73 shares significant amino-acid sequence identity with p53. Like p53, p73 recognizes canonical p53 DNA-binding sites and activates p53-responsive target genes and induces apoptosis. Moreover, SIRT1 binds to p53 while repressing the expression of their target genes. Here, we report that SIRT1 also binds to p73 and suppresses p73-dependent transcriptional activity. SIRT1 in human cells reduces the transcriptional activity of p73, and partly inhibits apoptosis induced by p73. Furthermore, SIRT1 can deacetylate p73 protein acetylation both in vivo and in vitro. Collectively, these data suggest that SIRT1 can modulate p73 activity via deacetylation.

Ionizing radiation (IR) affects the expression of a series of genes including genes involved in G1/S transition and the P53 pathway. Among those, reduction of SIRT1 was seen to be involved in transactivation of P53.

In this paper, we firstly give the definition of meromorphic function element and algebroid mapping. We also construct the algebroid function family in which the arithmetic, differential operations is closed. On basis of these works, we firstly proved the Second Main Theorem concerning small algebroid functions for v-valued algebroid functions.