Evaluating the Influence of a G-Quadruplex Prone Sequence on the Transactivation Potential by Wild-Type and/or Mutant P53 Family Proteins through a Yeast-Based Functional Assay.

Paola Monti,Natália Bohálová,Otília Porubiaková,Andrea Speciale,Alberto Inga,Vaclav Brazda,Gilberto Fronza,Renata Bocciardi,Paola Menichini

doi:10.3390/genes12020277

Abstract

P53, P63, and P73 proteins belong to the P53 family of transcription factors, sharing a common gene organization that, from the P1 and P2 promoters, produces two groups of mRNAs encoding proteins with different N-terminal regions; moreover, alternative splicing events at C-terminus further contribute to the generation of multiple isoforms. P53 family proteins can influence a plethora of cellular pathways mainly through the direct binding to specific DNA sequences known as response elements (REs), and the transactivation of the corresponding target genes. However, the transcriptional activation by P53 family members can be regulated at multiple levels, including the DNA topology at responsive promoters. Here, by using a yeast-based functional assay, we evaluated the influence that a G-quadruplex (G4) prone sequence adjacent to the p53 RE derived from the apoptotic PUMA target gene can exert on the transactivation potential of full-length and N-terminal truncated P53 family α isoforms (wild-type and mutant). Our results show that the presence of a G4 prone sequence upstream or downstream of the P53 RE leads to significant changes in the relative activity of P53 family proteins, emphasizing the potential role of structural DNA features as modifiers of P53 family functions at target promoter sites.

Highlights

Our data suggest that G4 prone sequences proximal to a P53 response elements (REs) lead to an overall reduction of P53 family proteins-dependent transactivation
Some functional features of mutant P53 family proteins can be affected by the placement of a G4 prone sequence adjacent to a P53 RE
RE can contribute to tuning P53 family proteins functions and should be considered as an important variable to fully characterize the P53 family cistrome

Summary

Introduction

The P53 family of transcription factors (TFs) is composed of P53, P63, and P73 proteins [1,2,3] that share an N-terminal transactivation domain, a central sequence-specific. At the C-terminus, a sterile α motif domain (SAM), probably involved in protein–protein interactions, is present only in P63 and P73 proteins. These TFs, by inducing a plethora of target genes, can influence different cellular pathways including proliferation, apoptosis, DNA repair, angiogenesis, senescence, metabolism, and differentiation [4,5]. All P53 family members can be transcribed starting from different promoters resulting in variants with different N-terminal sequences

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Conclusion