RESUMEN
Inhibitor of growth 2 (ING2) is involved in chromatin remodeling and it has previously been suggested that ING2 may regulate gene expression. The authors previously identified matrix metalloproteinase 13 (MMP13) as a target gene of ING2 in colorectal cancer. The aim of the present study was to identify novel genes regulated by ING2 and histone deacetylase 1 (HDAC1) and to clarify the biological significance of the ING2 structure. The present study generated the point mutant constructs of ING2 and deletion constructs consisting of partial ING2 to investigate the effect on gene expression and verify the interaction with HDAC1, mSin3A and sap30. A microarray was performed to find novel ING2/HDAC1 target genes using cell cooverexpression of ING2 and HDAC1. Plasminogen activator inhibitor1 (PAI1) was upregulated with overexpression of ING1b and ING2. The mutation of the PHD domain at 218 significantly attenuated the MMP13 and PAI1 expression, whereas the mutation at 224 resulted in increased expression. Furthermore, the expression levels were slightly reduced by the mutation of the Cterminal. The lack of the PHD domain and the Cterminal in ING2 resulted in a decreased ability to induce gene expression. The Cterminal with PHD domain, which lacked the Nterminal, maintained the transactive function for regulating the target genes. In addition to MMP13 and PAI1, eight genes [heat shock protein family A member 1A (HSPA1A), MIR73 host gene, chorionic somatomammotropin hormone 1, growth arrest and DNA damage inducible b, dehydrogenase/reductase 2, galectin 1, myosin light chain 1, and VGF nerve growth factor inducible] were demonstrated to be associated with ING2/HDAC1. The present study demonstrated that ING2/HDAC1 regulated PAI1 and HSPA1A expression and the PHD domain and the Cterminal of ING2, which are binding sites of HDAC1 and mSin3A, are essential regions for the regulation of gene expression.
