Liver-Specific Hepatocyte Nuclear Factor-4α Deficiency: Greater Impact on Gene Expression in Male than in Female Mouse Liver

Abstract

Hepatocyte nuclear factor (HNF)-4alpha is a liver-enriched transcription factor that regulates numerous liver-expressed genes including several sex-specific cytochrome P450 genes. Presently, a liver-specific HNF4alpha-deficient mouse model was used to characterize the impact of liver HNF4alpha deficiency on a global scale using 41,174 feature microarrays. A total of 4994 HNF4alpha-dependent genes were identified, of which about 1000 fewer genes responded to the loss of HNF4alpha in female liver as compared with male liver. Sex differences in the impact of liver HNF4alpha deficiency were even more dramatic when genes showing sex-specific expression were examined. Thus, 372 of the 646 sex-specific genes characterized by a dependence on HNF4alpha responded to the loss of HNF4alpha in males only, as compared with only 61 genes that responded in females only. Moreover, in male liver, 78% of 508 male-specific genes were down-regulated and 42% of 356 female-specific genes were up-regulated in response to the loss of HNF4alpha, with sex specificity lost for 90% of sex-specific genes. This response to HNF4alpha deficiency is similar to the response of male mice deficient in the GH-activated transcription factor signal transducer and activator of transcription 5b (STAT5b), where 90% of male-specific genes were down-regulated and 61% of female-specific genes were up-regulated, suggesting these two factors cooperatively regulate liver sex specificity by mechanisms that are primarily active in males. Finally, 203 of 648 genes previously shown to bind HNF4alpha near the transcription start site in mouse hepatocytes were affected by HNF4alpha deficiency in mouse liver, with the HNF4alpha-bound gene set showing a 5-fold enrichment for genes positively regulated by HNF4alpha. Thus, a substantial fraction of the HNF4alpha-dependent genes reported here are likely to be direct targets of HNF4alpha.

Genome-Wide Analysis of Chromatin States Reveals Distinct Mechanisms of Sex-Dependent Gene Regulation in Male and Female Mouse Liver

“…In liver, bimodal K4me1 loci occupied by FOXA2 are most likely to be cooccupied by HNF4A (13), and STAT5 binding sites in female liver show significant cooccupation by HNF4A, FOXA1, and FOXA2 (78). HNF4A is required for sexbiased gene expression and may act cooperatively with STAT5 to influence gene expression (35,36). Thus, FOXA1, and perhaps FOXA2, when recruited to male-biased DHS marked by malebiased K4me1, may act in cooperation with HNF4A and/or STAT5 to regulate sex-biased genes in male liver.…”

“…CUX2 is a female-specific, continuous GH-inducible repressor (33) that downregulates many male-biased genes and activates a subset of female-biased genes in female liver (34). Other liver-expressed TFs, including HNF4A and HNF6, are also important for hepatic sex differences, as indicated by knockout studies and reporter gene analyses and by the enrichment of their motifs at GH-dependent regulatory sites (35)(36)(37)(38)(39).…”

Neuronal SIRT1 regulates endocrine and behavioral responses to calorie restriction

“…Primer sequences were taken from the Harvard Primer Bank (Wang and Seed 2003;Spandidos et al 2008). For sexspecific gene expression in the liver, primer sequences were as described (Holloway et al 2008). …”

Dynamic, Sex-Differential STAT5 and BCL6 Binding to Sex-Biased, Growth Hormone-Regulated Genes in Adult Mouse Liver

“…STAT5 and BCL6 have opposing effects on the transcriptional regulation of several GH response genes (6,7,43), suggesting that BCL6 might modulate the sex-biased effects of STAT5 on liver gene expression (43). Other transcription factors implicated in GH-dependent, sex-differential liver gene expression include the liver-enriched factors HNF4A and HNF6/ Onecut1 (4,14,28,33,46) and the homeobox CDP family member CUX2 (CUTL2) (35). However, it is not known whether these factors cooperate with STAT5 to regulate liver sex differences.…”