Molecular insights into the role of the polyalanine region in mediating PHOX2B aggregation.
Luciano PironeLaura CaldinelliSimona Di LascioRocco Di GirolamoSonia Di GaetanoDiego FornasariLoredano PollegioniRoberta BenfanteEmilia Maria PedonePublished in: The FEBS journal (2019)
About 90% of congenital central hypoventilation syndrome (CCHS) patients show polyalanine triplet expansions in the coding region of transcription factor PHOX2B, which renders this protein an intriguing target to understand the insurgence of this syndrome and for the design of a novel therapeutical approach. Consistently with the role of PHOX2B as a transcriptional regulator, it is reasonable that a general transcriptional dysregulation caused by the polyalanine expansion might represent an important mechanism underlying CCHS pathogenesis. Therefore, this study focused on the biochemical characterization of different PHOX2B variants, such as a variant containing the correct C-terminal (20 alanines) stretch, one of the most frequent polyalanine expansions (+7 alanines), and a variant lacking the complete alanine stretch (0 alanines). Comparison of the different variants by a multidisciplinary approach based on different methodologies (including circular dichroism, spectrofluorimetry, light scattering, and Atomic Force Microscopy studies) highlighted the propensity to aggregate for the PHOX2B variant containing the polyalanine expansion (+7-alanines), especially in the presence of DNA, while the 0-alanines variant resembled the protein with the correct polyalanine length. Moreover, and unexpectedly, the formation of fibrils was revealed only for the pathological variant, suggesting a plausible role of such fibrils in the insurgence of CCHS.
Keyphrases
- transcription factor
- atomic force microscopy
- end stage renal disease
- single molecule
- gene expression
- newly diagnosed
- copy number
- ejection fraction
- chronic kidney disease
- case report
- high speed
- peritoneal dialysis
- binding protein
- single cell
- mass spectrometry
- protein protein
- dna binding
- cell free
- genome wide
- small molecule
- oxidative stress
- patient reported
- nucleic acid
- positive airway pressure