As a first result of our latest projects concerning the role of miRNA in liver regeneration the American Journal of Physiology - Regulatory, Integrative and Comparative Physiology has accepted our paper "Temporal expression profiles indicate a primary function for microRNA during the peak of DNA replication after rat partial hepatectomy": The liver has the unique capacity to regenerate after surgical resection. However, the regulation of liver regeneration is not completely understood. Recent reports indicate an essential role for small non-coding microRNAs (miRNAs) in the regulation of hepatic development, carcinogenesis, and early regeneration. We hypothesized that miRNAs are critically involved in all phases of liver regeneration after partial hepatectomy. We performed miRNA microarray analyses after 70% partial hepatectomy in rats under isoflurane anesthesia at different time points (0 hours - 5 days) and after sham laparotomy. Putative targets of differentially expressed miRNAs were determined using a bioinformatic approach. 2D-PAGE proteomic analyses and protein identification were performed on specimens at 0 and 24 hours after resection. The temporal dynamics of liver regeneration were characterized by BrdU, PCNA, IL-6, and HGF. We demonstrate that miRNA expression patterns changed during liver regeneration and that these changes were most evident during the peak of DNA replication at 24 hours after resection. Expression of thirteen miRNAs was significantly reduced 12-48 hours after resection (> 25% change), ouf of which downreguation was confirmed in isolated hepatocytes for 6 miRNAs at 24 hours, whereas three miRNAs were significantly upregulated. Proteomic analysis revealed 65 upregulated proteins; among them 23 represent putative targets of the differentially expressed miRNAs. We provide a temporal miRNA expression and proteomic dataset of the regenerating rat liver, which indicates a primary function for miRNA during the peak of DNA replication. These data will assist further functional studies on the role of miRNAs during liver regeneration. Authors are N. Raschzok, W. Werner, H. Sallmon, N. Billecke, C. Dame, P. Neuhaus and I.M. Sauer.