Rabbit Anti-Human KRT8 (Acetyl-Lys483) polyclonal antibody

The first lineage decision during mouse development is the establishment of trophectoderm and inner cell mass lineages, morphologically distinguishable at the blastocyst stage. The Caudal-like transcription factor Cdx2 is required for repression of inner cell mass genes Oct4 and Nanog in the trophectoderm. Expression of Cdx2 in the trophectoderm is thus one of the earliest known events in lineage determination. However, it is not clear whether the Cdx2 expression pattern is the cause or the consequence of this first lineage decision. Here, we show that Cdx2 is initially ubiquitously expressed, and becomes progressively upregulated in outside, future trophectoderm cells prior to blastocyst formation. Ubiquitous Cdx2 expression begins around the time of cell polarization, but we show that cell polarization is independent of zygotic Cdx2. Finally, we show functionally that Cdx2 is downstream of lineage allocation since Cdx2 mutant cells, which show cell-autonomous defects in expression of Oct4, Nanog, and the tropbectoderm marker Eomesodermin, do not preferentially contribute to inner cell mass in chimeric blastocysts. Cdx2 therefore appears to act downstream of the first lineage decision, suggesting that processes influencing lineage allocation or morphogenesis may regulate Cdx2 expression along the inside/outside axis of the embryo. (C) 2007 Elsevier Inc. All rights reserved.

Pregnant CD-1 mice received 200 ppm dimethylarsinic acid (DMA) in the drinking water from gestation day 8-18, and tumor formation was assessed in offspring at the age of 84 weeks. DMA elevated the incidence of lung adenocarcinoma (10.0%) and total tumors (33.3%) in male offspring compared to male control offspring (1.9 and 15.1%, respectively). DMA also elevated the incidence of hepatocellular carcinoma (10.0%) in male offspring compared to male control offspring (0.0%). DMA and its metabolites were detected in the lungs of transplacental DMA-treated neonatal mice. Transplacental DMA exposure increased cell proliferation in the epithelium in the lungs of both neonatal and 6-week-old male mice. Microarray and real-time PCR analyses detected high expression of keratin 8 (Krt8) in the lungs of both neonatal and 6-week-old DMA-treated mice. Western blot analysis indicated that DMA elevated methylation of histone H3K9, but not H3K27, in the lungs of male mice. Importantly, chromatin immunoprecipitation sequencing (ChIP-seq) analysis using an H3K9me3 antibody found differences in heterochromatin formation between mice exposed to DMA and the controls. Notably, ChIP-seq analysis also found regions of lower heterochromatin formation in DMA-treated mice, and one of these regions contained the Krt8 gene, agreeing with the results obtained by microarray analysis. High expression of Krt8 was also detected in adenoma and adenocarcinoma of the lung in male offspring. Overall, these data indicate that transplacental DMA treatment enhanced lung and liver carcinogenesis in male mice. In the lung, DMA caused aberrant methylation of histone H3K9, increased Krt8 expression, and enhanced cell proliferation.