Altered expression of the genes identified in this study may contribute to development of the heart failure phenotype and/or represent compensatory mechanisms to sustain cardiac function in failing human hearts.

Weaning is associated with reduced intestinal absorptive capacity in piglets. Our previous study indicated that dietary supplementation with N-carbamylglutamate (NCG) enhanced growth performance and improved intestinal function in weaned piglets. The present study was conducted to test the hypothesis that dietary supplementation with NCG may increase the growth performance of weaned piglets by regulating the expression of intestinal nutrient transporters, thus enhancing nutrient absorption. Twenty-four Huanjiang mini-pig piglets weaned at 21 d of age (3.17 ± 0.21 kg average BW) were randomly assigned to 2 dietary treatments consisting of a basal diet and the basal diet with 0.1% NCG supplementation for a 14-d period with 6 pens per treatment and 1 male and 1 female per pen. On d 14, 1 piglet was randomly selected from each pen for blood and tissue sampling. Dietary NCG supplementation enhanced (P < 0.05) growth rate and the efficiency of feed use in weaned Huanjiang mini-pig piglets. The NCG-supplemented diet increased (P < 0.05) mRNA expression levels of Slc6a19, Slc7a9, and Slc1a1 and the protein abundance of ASCT2, B(0)AT1, b(0,+)AT, y(+)LAT1, and EAAC1 in the jejunum. Furthermore, the contents of low density lipoprotein, ammonia, urea nitrogen, and AA as well as the activity of alkaline phosphatase in plasma were all altered (P < 0.05) by supplementation with NCG. These findings indicate that dietary supplementation with NCG may improve intestinal absorptive function in weaned piglets by increasing the expression of AA transporters in the intestine.

Background: CCAAT/Enhancer-binding Protein ␤ (C/EBP␤) inhibits differentiation of muscle satellite cells and is rapidly down-regulated in early myogenesis. Results: The E3 ubiquitin ligase Mouse double minute 2 homolog (Mdm2) targets C/EBP␤ for degradation thereby promoting entry into myogenesis. Conclusion: Mdm2 expression is necessary for entry into myogenesis. Significance: Establishes a new role for Mdm2 in cellular differentiation.

Bicoid (Bcd) is a transcriptional activator required for early embryonic patterning in Drosophila. Despite extensive studies, it currently remains unclear how Bcd activates transcription and what proteins participate in its activation process. In this report, we describe experiments to analyze the role of the Drosophila co-activator dCBP in Bcd-mediated activation. In Drosophila S2 cells, the Bcd activity is increased by the co-transfection of plasmids expressing dCBP and reduced by doublestranded RNA-mediated interference against dCBP. We further show that Bcd and dCBP can interact with each other and that Bcd-interacting domains of dCBP can cause dominant negative effects on Bcd activity in S2 cells. Our comparison of two Bcd-responsive enhancers, hunchback (hb) and knirps (kni), reveals a differential role of dCBP in facilitating Bcd activation. A dCBP mutant defective in its histone acetyltransferase activity exhibits a reduced, but not abolished, co-activator function for Bcd. Our chromatin immunoprecipitation experiments show that dCBP can increase not only the occupancy of Bcd itself at the enhancers but also the recruitment of general transcription factors to the promoter. Together, these experiments suggest that dCBP is an enhancer-dependent co-activator of Bcd, facilitating its activation through multiple mechanisms.

How Fanconi anemia (FA) protein D2 (FANCD2) performs DNA damage repair remains largely elusive. We report here that translesion synthesis DNA polymerase (pol) eta is a novel mediator of FANCD2 function. We found that wild type (wt) FANCD2, not K561R (mt) FANCD2, can interact with pol eta. Upon DNA damage, the interaction of pol eta with FANCD2 occurs earlier than that with PCNA, which is in concert with our finding that FANCD2 monoubiquitination peaks at an earlier time point than that of PCNA monoubiquitination. FANCD2-null FA patient cells (PD20) carrying histone H2B-fused pol eta and wtFANCD2, respectively, show a similar tendency of low Mitomycin C (MMC) sensitivity, while cells transfected with empty vector control or pol eta alone demonstrate a similar high level of MMC sensitivity. It therefore appears that FANCD2 monoubiquitination plays a similar anchor role as histone to bind DNA in regulating pol eta. Collectively, our study indicates that, in the early phase of DNA damage response, FANCD2 plays crucial roles in recruiting pol eta to the sites of DNA damage for repair.

Bicoid is a molecular morphogen-controlling embryonic patterning in Drosophila. It is a homeodomain-containing protein that activates specific target genes during early embryogenesis. Our recent studies have identified a domain of Bcd located outside its homeodomain and referred to as a self-inhibitory domain that can dramatically repress its own ability to activate transcription. Here we present evidence that the self-inhibitory function is evolutionarily conserved. A systematic analysis of this domain reveals a composite 10-amino acid motif with interdigitating residues that regulate Bcd activity in opposite manners. Mutations within the Bcd motif can exert their respective effects when the self-inhibitory domain is grafted to an entirely heterologous activator, but they do not affect DNA binding in vitro or subcellular localization of Bcd in cells. We further show that the self-inhibitory domain of Bcd can interact with Sin3A, a component of the histone deacetylase co-repressor complex. Our study suggests that the activity of Bcd is intricately controlled by multiple mechanisms involving the actions of co-repressor proteins.

Genetic selection strategies towards increased prolificacy have resulted in more and more increased littler size and incidences of impaired fetal development. Low birth weight (LBW) piglets, with long-term alterations in structure, physiology and metabolism, have lower survival rates and poor growth performance. The aim of the study was to compare the plasma, liver and skeletal muscle contents of neutral amino acids (NAA) and the intestinal expression of NAA transporters between LBW and high birth weight (HBW) suckling Huanjiang mini-piglets. Forty piglets with either LBW or HBW (20 piglets per group) were sampled on day 0, 7, 14 and 21 of age to give 5 observations per day per group. The contents of NAA in plasma, liver and skeletal muscle were measured, and jejunal expression of transporters for NAA, including Slc6a19 (B0AT1) and Slc1a5 (ASCT2), were determined by real-time RT-PCR and Western Blot, respectively. Results showed that the suckling piglets with LBW had higher contents of Thr, Ser, Gly, Ala, Val, Met, Ile, Leu, Tyr, Phe and Pro in liver, and Gly in skeletal muscle, whereas lower contents of Met, Ser and Ala in plasma when compared with the HBW littermates. Consistent with the content differences in plasma NAA, the jejunal expression profiles of both Slc6a19 (B0AT1) and Slc1a5 (ASCT2) in the LBW piglets were lower in compared with the HBW littermates during the early suckling period. These findings suggested that intestinal dysfunction in the LBW piglets may be one of the reasons in altered physiology and metabolism states of other organs, which result in lower survival and growth rate.

Bicoid (Bcd) is a Drosophila melanogaster morphogenetic gradient that controls embryonic patterning by activating target gene expression in a concentration-dependent manner. In this study we describe experiments to determine how different enhancers respond to Bcd distinctively, focusing on two natural Bcd-responsive enhancer elements, hunchback (hb) and knirps (kni). Our results show that, on the hb enhancer element, the amino-terminal domain of Bcd (residues 1 to 91) plays primarily an inhibitory role, whereas on the kni enhancer element this same Bcd domain plays a positive role at low protein concentrations. We further demonstrate that while the amino-terminal domain is largely dispensable for cooperative binding to the hb enhancer element, it is preferentially required for cooperative binding to the kni enhancer element. Alteration of the arrangement of Bcd binding sites in the kni enhancer element reduces the role of the amino-terminal domain in cooperative DNA binding but increases the effectiveness of the self-inhibitory function. In addition, elimination of symmetric pairs of Bcd binding sites in the kni enhancer element reduces both DNA binding and activation by Bcd. We propose that the amino-terminal domain of Bcd is an enhancer-specific switch that contributes to the protein's ability to activate different target genes in distinct manners.