Down regulation of extramacrochaetae mRNA by a Drosophila neural RNA binding protein Rbp9 which is homologous to human Hu proteins.
Rbp9 is an RNA binding protein expressed mainly in the central nervous system of adult Drosophilamelanogaster. Rbp9 shares a high degree of sequence similarity with human neural proteins referred to as Hu antigens. Hu antigens bind to U-rich mRNA destabilizing elements with a high affinity and, thus, have been implicated as regulators of mRNA stability. Using in vitro RNA binding assays, we found that Rbp9 binds strongly to poly U sequences. We then employed a Selex system to identify a consensus Rbp9 binding site (UUUXUUUU). Information obtained from the Selex results allowed the detection of two repeats of the Rbp9 consensus binding sequence in the 3' untranslated region of extramacrochaetae mRNA. UV crosslinking experiments demonstrated that Rbp9 interactsspecifically with emc mRNA. The requirement of Rbp9 protein in the down regulation of emc mRNA was confirmed by northern (RNA) analysis, which revealed that the level of emc mRNA increased 10-fold in rbp9 mutant flies. Taken together with the in vitro RNA binding results, the genetic evidence obtained strongly supports the hypothesis that Rbp9 functions as a regulator of RNA stability.
Park
S J
SJ
Laboratory of Molecular Genetics, Center for Basic Research, Samsung Biomedical Research Institute, Ilwon-dong 50, Kangnam-ku, Seoul 135-230, Korea.
Yang
E S
ES
Kim-Ha
J
J
Kim
Y J
YJ
D000818:Animals; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins; D001665:Binding Sites; D003001:Cloning, Molecular; D016384:Consensus Sequence; D003432:Cross-Linking Reagents; D004268:DNA-Binding Proteins / Q000235:genetics*; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000235:genetics*; D051959:ELAV Proteins; D005786:Gene Expression Regulation / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D011072:Poly U / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics; D012097:Repressor Proteins; D014466:Ultraviolet Rays
D051792:Basic Helix-Loop-Helix Proteins; D003432:Cross-Linking Reagents; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D051959:ELAV Proteins; D009419:Nerve Tissue Proteins; D011072:Poly U; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; C079911:Rbp9 protein, Drosophila; C067777:Sxl protein, Drosophila; C063577:emc protein, Drosophila