The microRNA-30 family is required for vertebrate hepatobiliary development.
OBJECTIVE
The function of microRNA (miRNA) in liver development is unknown. To address this issue, we characterized miRNA expression in the embryonic mouse liver, performed functional miRNA analysis in zebrafish larvae, and identified novel hepatic miRNA targets.


METHODS
Hepatic RNA isolated from mice at embryonic days 15.5, 18.5, and postnatal day 2 was hybridized to a mouse miRNA microarray. The microarray results were confirmed by Northern blot hybridization and quantitative reverse-transcription polymerase chain reaction. The spatial distribution of selected miRNAs was determined by in situ hybridization. Functional analysis of miR-30a was performed in zebrafish using antisense-mediated miRNA knockdown. Targets of miR-30a were identified by microarray analysis of gene expression following knockdown in cultured cells.


RESULTS
A set of 38 differentially expressed fetal hepatic miRNAs was identified. Several of these miRNAs were found to exhibit distinct temporal and spatial patterns of expression in hepatocytes, cholangiocytes, and nonepithelial cells within the liver. Two (miR-30a and miR-30c) are the first examples of ductal plate and bile duct-specific hepatic miRNAs. Knockdown of miR-30a in the zebrafish larva results in defective biliary morphogenesis. Several newly identified targets of miR-30a are known regulators of liver development and function.


CONCLUSIONS
We have identified miRNAs whose spatial and temporal patterns of expression are suggestive of functional roles in hepatic development and/or function. One of these, the biliary miRNA miR-30a, is required for biliary development in zebrafish. This is the first demonstration of a functional role for miRNA in hepatic organogenesis.
Hand
Nicholas J
NJ
Department of Pediatrics, Division of Gastroenterology, Hepatology, and Nutrition, University of Pennsylvania School of Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.
Master
Zankhana R
ZR
Eauclaire
Steven F
SF
Weinblatt
Daniel E
DE
Matthews
Randolph P
RP
Friedman
Joshua R
JR
D000263:Adenylate Kinase / Q000235:genetics; D000818:Animals; D001324:Autoantigens / Q000235:genetics; D001652:Bile Ducts / Q000196:embryology / Q000502:physiology; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D008099:Liver / Q000196:embryology* / Q000502:physiology*; D051379:Mice; D008815:Mice, Inbred Strains; D035683:MicroRNAs / Q000235:genetics*; D041681:NIH 3T3 Cells; D020411:Oligonucleotide Array Sequence Analysis; D016601:RNA-Binding Proteins; D014714:Vertebrates; D015027:Zebrafish
D001324:Autoantigens; D035683:MicroRNAs; D016601:RNA-Binding Proteins; C465663:TNRC6A protein, human; D000263:Adenylate Kinase