Ubiquitin C gene: Structure, function, and transcriptional regulation

Lucia Radici,Rita Crinelli,Marzia Bianchi,Mauro Magnani

doi:10.4236/abb.2013.412141

Abstract

Ubiquitin C (UbC) is one of the four genes encoding for ubiquitin in the mammalian genome. It has been described as the most responsive gene to cellular treats such as UV irradiation, heat shock, oxidative stress and translational impairment; it was also reported to contribute to maintaining ubiquitin steady state levels under physiological conditions. Despite the bulk of knowledge concerning its function, little is known about the molecular mechanisms modulating UbC expression. Here we review the state of the art of UbC structure, function and transcriptional regulation. Starting from the first evidences which circumscribed the genomic region, pointing out both basic promoter marks (such as transcription start site and TATA-like element), and transcript structure (exonintron boundaries) we go through more detailed molecular studies performed by Marinovic in 2002 and by Bianchi et al. in 2009 and 2013. Herein, the key players orchestrating UbC gene basal activity are underlined.

Highlights

Ubiquitin (Ub) is a highly conserved 76 amino acid protein which can be conjugated to other proteins via an isopeptide linkage between the carboxy-terminal glycine residue of ubiquitin and the ε-amino group of a lysine within the target protein or it can make an isopeptide bond with a lysine in another moiety of ubiquitin to form Ub chains
Ubiquitin homeostasis is maintained through different mechanisms: recycling of ubiquitin chains by deubiquitinating enzymes (DUBs) and de novo synthesis (“Figure 1”) [10]
UBA52 and RPS27a code for a single copy of ubiquitin fused to the ribosomal proteins L40 and S27a whereas UbB and Ubiquitin C (UbC) are polyubiquitin genes and encode 3 and 9 head-to-tail repeats of ubiquitin, respectively These genes were first characterized by Wiborg et al in 1985 [11] using Northern blotting analysis of poly(A)-containing RNA from different tissues, but only few years later they were localized in the genome and fully characterized [12,13,14,15]

Summary

INTRODUCTION

Ubiquitin (Ub) is a highly conserved 76 amino acid protein which can be conjugated to other proteins via an isopeptide linkage between the carboxy-terminal glycine residue of ubiquitin and the ε-amino group of a lysine within the target protein or it can make an isopeptide bond with a lysine in another moiety of ubiquitin to form Ub chains. This post-translational modification is known to play a central role in the regulation of various cellular processes: the number and placement of Ub molecules added to a protein help to determine its fate. Ubiquitin homeostasis is maintained through different mechanisms: recycling of ubiquitin chains by deubiquitinating enzymes (DUBs) and de novo synthesis (“Figure 1”) [10]

UBIQUITIN GENES

UBC TRANSCRIPTIONAL REGULATION

Findings

CONCLUSIONS