Insights into Network of Hot Spots of Aggregation in Nucleophosmin 1

Int J Mol Sci. 2022 Nov 25;23(23):14704. doi: 10.3390/ijms232314704.

Abstract

In a protein, point mutations associated with diseases can alter the native structure and provide loss or alteration of functional levels, and an internal structural network defines the connectivity among domains, as well as aggregate/soluble states' equilibria. Nucleophosmin (NPM)1 is an abundant nucleolar protein, which becomes mutated in acute myeloid leukemia (AML) patients. NPM1-dependent leukemogenesis, which leads to its aggregation in the cytoplasm (NPMc+), is still obscure, but the investigations have outlined a direct link between AML mutations and amyloid aggregation. Protein aggregation can be due to the cooperation among several hot spots located within the aggregation-prone regions (APR), often predictable with bioinformatic tools. In the present study, we investigated potential APRs in the entire NPM1 not yet investigated. On the basis of bioinformatic predictions and experimental structures, we designed several protein fragments and analyzed them through typical aggrsegation experiments, such as Thioflavin T (ThT), fluorescence and scanning electron microscopy (SEM) experiments, carried out at different times; in addition, their biocompatibility in SHSY5 cells was also evaluated. The presented data clearly demonstrate the existence of hot spots of aggregation located in different regions, mostly in the N-terminal domain (NTD) of the entire NPM1 protein, and provide a more comprehensive view of the molecular details potentially at the basis of NPMc+-dependent AML.

Keywords: ThT fluorescence; aggregation; bioinformatic prediction.

MeSH terms

  • Amyloid / metabolism
  • Amyloidogenic Proteins / genetics
  • Humans
  • Leukemia, Myeloid, Acute* / genetics
  • Leukemia, Myeloid, Acute* / metabolism
  • Mutation
  • Nuclear Proteins / metabolism
  • Nucleophosmin* / genetics

Substances

  • Amyloid
  • Amyloidogenic Proteins
  • Nuclear Proteins
  • Nucleophosmin
  • NPM1 protein, human

Grants and funding

This research received no funding.