Elevation and characteristics of Rab30 and S100a8/S100a9 expression in an early phase of liver regeneration in the mouse

Gene expression profiling of sense and antisense transcripts in liver regeneration by microarray analysis

Liver regeneration is a hyperplastic phenomenon induced by partial hepatectomy (PH) or hepatic damage. A large number of genes have been indicated to be involved in the process of liver regeneration. It was recently reported that natural antisense transcripts are involved in the regulation of gene expression. However, no antisense transcript expressions in liver regeneration have been reported thus far. Therefore, the present study aimed to comprehensively identify up- or downregulated sense and antisense transcripts in liver regeneration using PH mice and a sense/antisense custom-microarray. The results showed that 97 genes were upregulated and 7 genes were downregulated for sense transcripts, whereas 15 genes were upregulated and 2 genes were downregulated for antisense transcripts in regenerating livers as compared to normal livers (P<0.05 and fold change >2.0). Sense and antisense transcripts of the genes, Apoa4, Hp, Fgb and Fgg, exhibited concordant upregulation during the course of liver regeneration. Apoa4, Hp and Fgb transcripts were further investigated by strand-specific reverse transcription-quantitative polymerase chain reaction (RT-qPCR), revealing results consistent with those of the microarray. In conclusion, the up- or downregulated sense and antisense transcripts identified in the present study are suggested to be involved in liver regeneration.

Hepatocyte-specific S100a8 and S100a9 transgene expression in mice causes Cxcl1 induction and systemic neutrophil enrichment

Background

Calprotectin consists of the Ca²⁺-binding proteins S100a8 and S100a9 that are induced in epithelial cells in response to tissue damage and infection. Both proteins are also secreted by activated innate immune cells and numerous studies demonstrate their crucial role in pathological conditions of acute and chronic inflammation.

Results

Here, we established a conditional mouse model with simultaneous S100a8 and S100a9 transgene expression in hepatocytes (TgS100a8a9^hep) under the control of doxycycline to unravel the role of epithelial-derived Calprotectin on tissue homeostasis and inflammation. TgS100a8a9^hep mice displayed a significant enrichment of neutrophils in peripheral blood and tissues with high blood content. Interestingly, Cxcl1 transcription was significantly induced in the liver of TgS100a8a9^hep mice and primary hepatocytes derived thereof as compared to Control mice, accompanied by an increase of Cxcl1 serum levels. However, expression of other chemokines with a known function in neutrophil mobilization from the bone marrow, e.g. Csf3 and Cxcl2, was not altered. Doxycycline treatment of TgS100a8a9^hep mice reduced Cxcl1 expression in the liver and resulted in normal numbers of neutrophils.

Conclusion

In summary, our data demonstrate for the first time that hepatocyte-specific S100a8 and S100a9 expression induces a systemic mobilization of neutrophils by a specific activation of Cxcl1 transcription in the liver.

Effects of high fat feeding on liver gene expression in diabetic goto-kakizaki rats

Effects of high fat diet (HFD) on obesity and, subsequently, on diabetes are highly variable and modulated by genetics in both humans and rodents. In this report, we characterized the response of Goto-Kakizaki (GK) rats, a spontaneous polygenic model for lean diabetes and healthy Wistar-Kyoto (WKY) controls, to high fat feeding from weaning to 20 weeks of age. Animals fed either normal diet or HFD were sacrificed at 4, 8, 12, 16 and 20 weeks of age and a wide array of physiological measurements were made along with gene expression profiling using Affymetrix gene array chips. Mining of the microarray data identified differentially regulated genes (involved in inflammation, metabolism, transcription regulation, and signaling) in diabetic animals, as well as the response of both strains to HFD. Functional annotation suggested that HFD increased inflammatory differences between the two strains. Chronic inflammation driven by heightened innate immune response was identified to be present in GK animals regardless of diet. In addition, compensatory mechanisms by which WKY animals on HFD resisted the development of diabetes were identified, thus illustrating the complexity of diabetes disease progression.