p53Ψ is a transcriptionally inactive p53 isoform able to reprogram cells toward a metastatic-like state

Area of Science:

• Molecular Biology
• Cancer Research
• Genetics

Background:

• The tumor suppressor protein p53 (encoded by the TP53 gene) plays a critical role in cellular responses to stress.
• While p53's canonical functions are well-studied, the regulation and functional diversity of p53 responses remain incompletely understood.
• Alternative splicing is a key mechanism for generating protein diversity from a limited number of genes.

Purpose of the Study:

• To investigate novel regulatory mechanisms of p53.
• To characterize a newly identified p53 isoform generated by alternative splicing.
• To elucidate the molecular function and cellular impact of this unique p53 isoform.

Main Methods:

• Analysis of TP53 gene alternative splicing.
• Identification and characterization of a novel p53 isoform (p53Ψ) using molecular biology techniques.
• Assessment of p53Ψ's DNA binding and transcriptional activity.
• Evaluation of p53Ψ's effects on epithelial-mesenchymal transition (EMT) markers, cell motility, and invasion.
• Investigation of p53Ψ's mechanism of action involving mitochondrial regulation.

Main Results:

• A unique p53 isoform, p53Ψ, was identified, generated by alternative splicing of the TP53 gene.
• p53Ψ lacks the ability to bind DNA and transactivate canonical p53 target genes.
• p53Ψ attenuates E-cadherin expression and induces EMT markers, enhancing cell motility and invasion.
• p53Ψ exerts its prometastatic effects independently of transcriptional activity, via regulation of cyclophilin D and mitochondrial permeability.

Conclusions:

• p53Ψ represents a novel 'separation-of-function' isoform of p53.
• This isoform lacks tumor suppressor activities but promotes a prometastatic program.
• p53Ψ mediates its effects through transcriptionally independent mechanisms involving mitochondrial regulation.