Figure 4.

DUSP11 directly dephosphorylates the BLV pre-miRNAs and 5p miRNAs. (A) Immunoblot analysis to confirm expression of DUSP11 and DUSP11 catalytic mutant proteins generated using in vitro transcription/translation. The membrane was probed using anti-DUSP11 and anti-tubulin antibodies. (B) In vitro phosphatase reactions on the [γ-32P]-BLV-pre-miR-B5 mimic and [γ-32P]-BLV-miR-B5-5p miRNA mimic using CIP (positive control) or the in vitro translated DUSP11, DUSP11 catalytic mutant, or luciferase (negative control) from A. Reactions were fractionated on 15% PAGE/8 M urea, and RNAs were stained with EtBr. RNAs were then transferred to a membrane, exposed to a storage phosphor screen, and imaged on a Typhoon bimolecular imager. (C) Northern blot analysis from wild-type and DUSP11 knockout HEK293T cells transfected with a 5′ triphosphorylated BLV-B5 pre-miRNA mimic pretreated with (+) or without (−) RNA 5′ polyphosphatase. The blot was first probed for the 5p miRNA arm (green), stripped, and reprobed for the 3p arm (orange). Note that a lighter exposure for the input RNA is shown as compared with the RNA recovered from cells.