Gonadotropin synthesis and release is dependent upon pulsatile stimulation by the hypothalamic neuropeptide GnRH. Generally, slow GnRH pulses promote FSH production while rapid pulses favor LH, but the molecular mechanism underlying this pulse sensitivity is poorly understood. In this study, we develop and test a model for FSH[beta] regulation in mouse L[beta]T2 gonadotropes. We observed that positive regulators of FSH[beta] expression, such as c-fos and c-jun, were upregulated at slower pulse frequencies than a number of potential negative regulators, such as the co-repressors SnoN, CREM and TGIF1. These latter co-repressors reduced FSH[beta] promoter activity whether driven by transfection of individual transcription factors or by treatment with GnRH and activin. Overexpression of Smad binding or phosphorylation defective SnoN and TGIF mutants, however, failed to repress FSH[beta] promoter activity. Knock down of the endogenous repressors SnoN and TGIF, but not CREM, increased FSH[beta] promoter activity driven by continuous GnRH or activin. ChIP analysis showed that c-fos, SnoN and TGIF1, and to a lesser degree c-jun, occupy the FSH[beta] promoter in a cyclical manner following GnRH stimulation. Overexpression of corepressors SnoN or TGIF repressed induction of the FSH[beta] promoter at the slow GnRH pulse frequency, but had little effect at the fast pulse frequency. In contrast, knock down of endogenous SnoN or TGIF selectively increased FSH[beta] mRNA at the fast GnRH pulse frequency. Finally, relative to corepressors, stimulators have greater FSH[beta] promoter occupancy at slow GnRH pulse frequency which favors greater FSH[beta] mRNA production. Therefore, we propose a potential mechanism by which production of gonadotropin FSH[beta] is modulated by positive transcription factors and negative corepressors with different pulse sensitivities

Epithelial to mesenchymal transition transcription factors (EMT-TFs) such as SNAI2 have been found to be expressed endogenously in epidermal stem and progenitor cells and downregulated upon differentiation. The presence of SNAI2 in progenitor cells is necessary to repress the expression of differentiation genes by binding directly to their promoters. SNAI2 is downregulated upon differentiation which allows expression of differentiation genes. Furthermore overexpression of SNAI2 can block the differentiation process suggesting that the levels of SNAI2 are crucial to epidermal cell fate decisions. To address on a genome wide level the genes that are impacted by changing the levels of SNAI2, we performed microarray analysis on SNAI2 knockdown and overexpressing epidermal progenitor cells. Here we provide a detailed methods and analysis on these microarray data which has been deposited in Gene Expression Omnibus (GEO): GSE55269.

Cell fate commitment during development is achieved through the expression of lineage-specific transcription factors. Recent studies have suggested that the expression of combinations of these lineage-specific transcription factors can convert adult somatic cells from one type to another. Here we report that the combination of p63, a master regulator of epidermal development and differentiation, and KLF4, a regulator of epidermal differentiation, is sufficient to convert dermal fibroblasts to a keratinocyte phenotype. Induced keratinocytes (KCs) expressed KC-specific proteins and had a transcriptome similar to KCs. Reprogramming to a KC phenotype was rapid and efficient with a vast majority of cells morphologically resembling and expressing KC-specific genes within a week of p63 and KLF4 transduction. Furthermore, p63 and KLF4 are capable of inducing a KC phenotype even in a cancerous cell line, highlighting their importance for epidermal specification. The robustness of the conversion process also allows the use of this as a model system to study the mechanisms of reprogramming.