Functional analysis and characterization of the human RBBP6 promoters based on a combination of molecular biology and in silico approaches provide additional evidence for RBBP6 role in apoptosis

Abstract

Retinoblastoma Binding Protein 6 (RBBP6) has been
implicated in the apoptotic pathway and regulation of the cell
cycle through its interaction with p53, Rb and YB1 and
ubiquitination of YB1. Analysis of transcripts indicated the
existence of two promoters responsible for the regulation of the
gene namely Promoter 0 (P0) and Promoter 1 (P1). With a
combination of molecular and computational techniques we
analysed and functionally characterised these two promoters of
the RBBP6 gene. In this study, we demonstrate that the activity
of both promoters increase following camptothecin-induced
apoptosis, with notable difference in activities of P0 relative to
P1, though activities of both have increased. Computational
analysis suggests that both P0 and P1 transcription start sites are
located within CpG islands, and that P1 has a functional TATAbox
contrary to P0. Promoter content analysis further suggested
the presence of six-transcription factor binding sites that are
common to both promoters and several others unique to each
promoter. Functional analysis of all the transcription factors
using GO, KEGG and DAVID analysis, associated P0 more
strongly with apoptosis, while P1 was associated more with the
regulation of the cell cycle. In addition, P1 was also associated
with ubiquitin-mediated proteolysis, while both promoters have
been associated with the antigen processing and presentation
pathway. Although an association between RBBP6 and cancer
has already been made, we also found additional associations
with diabetes and Alzheimer’s disease.