SIRT1 affects DNA methylation of polycomb group protein target genes, a hotspot of the epigenetic shift observed in ageing

Table 1 Analysis of the size of intersections between polycomb group protein target genes (PCGTs) and genes with higher levels of DNA methylation

	HuVEC				Caco-2
	Positive response to SIRT1		Negative response to SIRT1		Positive response to SIRT1		Negative response to SIRT1
	RF	P	RF	P	RF	P	RF	P
Suz12 targets	1.5	<0.0001	1.5	=0.0008	1.6	<0.0001	1.5	=0.0088
Eed targets	1.4	=0.0102	1.1	=0.4573	1.8	<0.0001	1.5	=0.0347
Phc1 targets	1.4	=0.0069	1.3	<0.0001	1.6	<0.0001	1.7	=0.0004
Rnf2 targets	1.2	=0.0853	1.3	=0.0341	1.7	<0.0001	1.7	=0.0012
Targets of all polycomb group proteins	1.6	<0.0001	1.1	=0.6135	2.2	<0.0001	1.4	=0.1355
Targets of at least one polycomb group protein	1.3	=0.0090	1.3	=0.0046	1.5	<0.0001	1.6	<0.0001

Analysis of the size of intersections between polycomb group protein target genes (PCGTs) and genes with higher levels of DNA methylation under control conditions and/or reduced levels of DNA methylation under conditions of SIRT1 knockdown (positive response to SIRT1) or genes with reduced levels of DNA methylation under control conditions and/or higher levels of DNA methylation under conditions of SIRT1 knockdown (negative response to SIRT1). PCGT lists were compiled from published data (Boyer et al. 2006). RF (representation factor) values show the ratio of observed to expected number of genes in the intersection. P values were derived using chi-square analysis applying Yates’ correction. Italicized cells indicate where data did not reach statistical significance

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