CNBP, the product of myotonic dystrophy type 2 gene, is a nucleic acid chaperone that may control gene expression through G-quadruplex formation promotion.

ARMAS, P.; BORGOGNONE, M.; MARGARIT, E.; CALCATERRA, N. B.

Iguazú

Simposio; Symposium "Gene Expression and RNA Processing".; 2011

International Centre for Genetic Engineering and Biotechnology (ICGEB).

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:595.3pt 841.9pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:35.4pt; mso-footer-margin:35.4pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Cellular nucleic acid binding protein (CNBP) is encoded by the ZNF9 gene. An expansion of CCTG repeats in intron 1 of human ZNF9 gene causes Myotonic Dystrophy type 2 (DM2), a genetic disease which symptoms can be partially explained by the reduction of the global protein synthesis due to reduced CNBP levels. CNBP was also implicated in embryonic craniofacial development controlling cell proliferation/death balance in cranial neural crest cells. It is a small and highly conserved protein that binds G-rich single-stranded DNA and RNA and acts as a nucleic acid chaperone. Diverse reported CNBP targets range from DNA regulatory sites in gene promoters to translational regulatory elements in untranslated regions of mRNAs. Here, by means of DNA polymerase Stop Assays, Circular Dichroism spectroscopy, and Electrophoretic Mobility Shift Assays, we show that CNBP favors the folding of intramolecular parallel G-quadruplex (G4) structures in vitro. Moreover, CNBP activates luciferase transcription in cell cultures though a stable G4 forming sequence present in the human c-myc proto-oncogene promoter. CNBP genomic targets were identified through a genome-wide screening using inverse yeast one-hybrid strategy on genomic zebrafish and mouse libraries. CNBP recognized DNA fragments enriched in putative G4 sequences and containing the 14-nucleotides consensus sequence NGGGGG(A/T)GGGGGGN. Putative targets were classified considering gene proximity, gene ontology and gene co-expression with CNBP. Most relevant targets were selected for functional in vivo confirmation in CNBP-depleted zebrafish embryos. Gathering these results, we propose that CNBP functions as a nucleic acid chaperone that may control gene expression through G-quadruplex formation promotion.