title: Effect of Modulation of hnRNP L Levels on the Decay of bcl-2 mRNA in MCF-7 Cells.
abstract: It has been shown that CA repeats in the 3'-untranslated region (UTR) of bcl-2 mRNA contribute the constitutive decay of bcl-2 mRNA and that hnRNP L (heterogenous nuclear ribonucleoprotein L) interacts with CA repeats in the 3'-UTR of bcl-2 mRNA, both in vitro and in vivo. The aim of this study was to determine whether the alteration of hnRNP L affects the stability of bcl-2 mRNA in vivo. Human breast carcinoma MCF-7 cells were transfected with hnRNP L-specific shRNA or hnRNP L-expressing vector to decrease or increase hnRNP L levels, respectively, followed by an actinomycin D chase. An RT-PCR analysis showed that the rate of degradation of endogenous bcl-2 mRNA was not affected by the decrease or increase in the hnRNP L levels. Furthermore, during apoptosis or autophagy, in which bcl-2 expression has been reported to decrease, no difference in the degradation of bcl-2 mRNA was observed between control and hnRNP L-knock down MCF-7 Cells. On the other hand, the levels of AUF-1 and nucleolin, transacting factors for ARE in the 3'UTR of bcl-2 mRNA, were not significantly affected by the decrease in hnRNP L, suggesting that a disturbance in the quantitative balance between these transacting factors is not likely to interfere with the effect of hnRNP L. Collectively, the findings indicate that the decay of bcl-2 mRNA does not appear to be directly controlled by hnRNP L in vivo.
authors.affiliation: Department of Biochemistry, College of Medicine, The Catholic University of Korea, Seoul 137-701, Korea.
authors.forename: Mi-Hyun
authors.initials: MH
authors.lastname: Lim
authors.forename: Dong-Hyoung
authors.initials: DH
authors.lastname: Lee
authors.forename: Seung Eun
authors.initials: SE
authors.lastname: Jung
authors.forename: Dong-Ye
authors.initials: DY
authors.lastname: Youn
authors.forename: Chan Sun
authors.initials: CS
authors.lastname: Park
authors.forename: Jeong-Hwa
authors.initials: JH
authors.lastname: Lee