Can Affimer technology help to unravel the mysteries of p53?

This week we’re taking a closer look at the field of cell cycle research, focussing in particular on p53. With the cellular functions of this protein seemingly ever increasing where might Affimer technology fit into this research field?

Since its simultaneous discovery by a number of groups in 1979 p53 has been widely researched and shown to be involved in a whole host of processes beyond its key role as a tumour suppressor – from reproduction and the regulation of metabolic processes, to genomic repair, fidelity and recombination. The field of p53 research is vast with new areas of interest opening up and it seems more answers to find regarding the function of this promiscuous protein.
Tumor protein p53 binding protein 1
Tumor protein p53 binding protein 1

While it has been evident for some time that the p53 protein integrates an assortment of cellular stress responses to determine the appropriate result, either as apoptosis or cell cycle arrest, current research is uncovering a new set of p53 functions: the integration of the central nervous system, immune system and metabolic functions, regulation of aging processes and stem cell production and roles in diseases such as cancer and diabetes. How each of the many mutations known to occur in p53 affect its role in these different systems must also be analysed, adding an extra layer of complexity.

Analysis of any cellular system requires adequate tools. For the study of proteins in molecular biology and biochemistry these tools have often consisted of antibodies and aptamers. Although the majority of the mutations identified in p53 are located within the DNA-binding domain at the centre of the molecule, antibodies that bind specifically to this region have proven difficult to generate, thus the bulk of available antibodies are not specific enough to distinguish between the WT and mutant versions of this protein.
The use of affinity reagents is essential for the immunohistochemical detection of p53 in tissue samples, which has important diagnostic, prognostic and therapeutic applications. Yet the reliance upon reagents which are acknowledged to vary as much as antibodies in these assays is clearly problematic. Equally, due to the lack of antibody specificity in this field, positive staining for p53 does not always equate to a p53 mutation and so the interpretation of such samples is tricky and requires highly skilled specialists to perform these assays. The increased standardisation and specificity offered by aptamers and Affimer technology along with their smaller molecular weight allowing better tissue penetration for higher signals show obvious advantages in such situations.
Aptamers targeting p53 are not widely used in the field, possibly due to the lack of conformational diversity inherent in the nucleic acid structure of such molecules, which prevents the selection of specific adequate binders to the p53 protein. This may also stem from the inherent project-specific nature of aptamers, which limits their use outside of the labs in which they were generated.
The future of the p53 field of research as it travels in exciting new directions will undoubtedly be filled with surprises. Offering specific protein detection of different isoforms, with no batch-to-batch variation and the opportunity to carry out expression and functional studies using just one reagent, Affimer binders can help researchers to advance this field.