MicroRNAs: Tissue Expression and Role in 3T3-L1 Pre-Adipocyte Differentiation

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Title: MicroRNAs: Tissue Expression and Role in 3T3-L1 Pre-Adipocyte Differentiation
Author: Sun, Tingwan
Abstract: MicroRNAs , which are endogenous small RNAs around 22 nucleotides , play important roles in many physiological processes . We investigated whether microRNAs regulate 3T3 -L1 pre -adipocyte differentiation . The expression of microRNAs during 3T3 -L1 pre -adipocyte differentiation was detected by microarrays and confirmed by northern blot and quantitative real time PCR . Several microRNAs , including let -7 , were up -regulated at the late stage of 3T3 -L1 adipogenesis . let -7 expression specifically increased during the late stage of 3T3 -L1 differentiation and ectopic introduction of let -7 in 3T3 -L1 cells before hormonal induction inhibited 3T3 -L1 adipogenesis . Both the mRNA and protein levels of HMGA2 , a target of let -7 , decreased with ectopic let -7 presence in 3T3 -L1 cells . Also , HMGA2 protein level was inversely correlated to let -7 levels during 3T3 -L1 adipogenesis . Knock -down of Hmga2 or E2f1 by siRNA inhibited 3T3 -L1 pre -adipocyte differentiation . Our results suggest let -7 can stop clonal expansion of 3T3 -L1 cells and bring them to final growth arrest and terminal differentiation by targeting Hmga2 . In an effort to explore the role of microRNA , the expression of 111 microRNAs in 36 mouse tissues was detected by quantitative real time PCR . MicroRNAs either show universal expression in all tissues or specific expression in certain tissues , suggesting their roles in these tissues . Different isotypes of the same microRNAs or microRNAs transcribed from the same genomic location show similar expression pattern in mouse tissues . Hierarchical cluster analysis based on the expression of microRNA in tissues showed that tissues having similar physiologic functions or anatomic locations clustered together , suggesting the roles of microRNAs might be consistent with the functions of the tissues in which they are expressed . Comparison of the expression of microRNAs with that of nuclear receptors in mouse tissues showed positive correlations between a select number of nuclear receptors and microRNAs , but these relationships need to be verified by experimental data . In all , the expression profile of microRNAs in mouse tissues provides a useful tool for microRNA studies .
URI: http : / /hdl .handle .net /2152 .5 /399
Date: 2009-01-14

Citation

MicroRNAs: Tissue Expression and Role in 3T3-L1 Pre-Adipocyte Differentiation. Graduate School of Biomedical Sciences. Available electronically from http : / /hdl .handle .net /2152 .5 /399 .

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