Dgcr8del/fl, Alb-Cre+/−, and Dgcr8fl/fl mice were generated from matings of Dgcr8del/fl mice on a mixed C57Bl/6, 129S4 background10 with Alb-Cre+/− mice on a C57Bl/6 background (Jackson Laboratory).11, 12 Eight to 12-week-old male mice were used in this study. All procedures involving mice were approved by the Institutional Animal Care Committee at the University of California San Francisco. Two-thirds of the liver

was surgically removed under isoflurane anesthesia as described.5 One 3-deazaneplanocin A hundred μg/g body weight 5-bromo-2-deoxyuridine (BrdU, Roche) was injected intraperitoneally 35 hours after surgery. Total RNA was isolated with Trizol and treated with DNase I (Ambion) to eliminate genomic DNA. One μg RNA was used for cDNA synthesis with Superscript III reverse transcription reagent (Invitrogen). PCR amplification was performed at 50°C for 2 minutes and 95°C for 10 minutes, followed by 40 cycles at 95°C for 15 seconds and 60°C for 1 minute in a 7300 real-time PCR system with SYBR green (Applied Biosystems). For each

sample we analyzed β-actin, Gapdh, or 18S rRNA expression to normalize target gene expression. Primers for qRT-PCR were designed with Primer Express software (Applied Biosystems). Dgcr8 primers were designed to target the deleted exon 3. For miRNA analysis, RNA was isolated PD0325901 manufacturer with the miRNeasy kit (Qiagen). Ten ng RNA was used for miRNA-specific cDNA synthesis with the TaqMan MicroRNA Reverse Transcription Kit and Taqman MicroRNA Assays (all Applied Biosystems). PCR amplification was performed at 95°C for 10 minutes, this website followed by 40 cycles at 95°C for 15 seconds and 60°C for 1 minute in a 7900 real-time PCR system (Applied Biosystems). The small RNA Sno202 was used to normalize target miRNA expression. Relative changes in gene and miRNA expression were determined using the 2-ΔΔCt method.13 Paraffin-embedded liver samples were sectioned and stained

with the antibodies rabbit anti-Cyclin D (NeoMarkers), mouse anti-PCNA (Biosource), and rabbit anti-Ki67 (Lab Vision) at 1:100 dilutions. To visualize immunocomplexes for light microscopy with 3,3′-diaminobenzidine (DAB), we used biotinylated antirabbit or antimouse IgG antibodies and the ABC reagent (all Vector). Immunostainings with rat anti-A6 (gift from Dr. Valentina Faktor, NCI), rabbit anti-DGCR8 (Proteintech), and rat anti-BrdU (Abcam) antibodies were performed on sections of frozen liver samples embedded in optimum cutting temperature compound (Tissue-Tek, Sakura Finetek) at 1:250, 1:50, and 1:100 dilution, respectively. For fluorescence microscopy, the secondary antibodies goat antirat conjugated with Alexa Fluor 488, goat antirabbit conjugated with Alexa Fluor 594, and goat antirat conjugated with Alexa Fluor 594 (all Molecular Probes) were used at 1:500 dilutions.