Cell-density (cycle) Dependent Silencer of the Rat Insulin-like Growth Factor Binding Protein-2 (IGFBP-2) Gene

Abstract

An element which has a negative effect on transcription has been identified in the 5′-flanking region of the rat insulin-like growth factor binding protein-2 (IGFBP-2) gene. This element was confirmed to be a silencer by truncation or by linking it to a heterologous promoter. The silencer activity disappeared in the growth-arrested BRL-3A cells at the G1/S border by high cell density where the IGFBP-2 production is highly elevated. This observation may represent a novel mechanism through which gene expression is controlled by modulation of a silencer. Taken together, these results suggest a regulatory link between cell growth and IGFBP-2 expression regulated by its silencer.

Key Words:

• Growth factor
• cell-cycle
• cancer
• transcription repression