Identification of a male-specific RNA binding protein that regulates sex-specific splicing of Bmdsx by increasing RNA binding activity of BmPSI.
Bmdsx is a sex-determining gene in the silkworm and is alternatively spliced in males and females. CE1 is a splicing silencer element responsible for the sex-specific splicing of Bmdsx. To identify sex-specific factors implicated in the sex-specific splicing of Bmdsx, we performed RNA affinity chromatography using CE1 RNA as a ligand. We have identified BmIMP, a Bombyx homolog of IGF-II mRNA binding protein (IMP), as a male-specific factor that specifically binds to CE1. The gene encoding BmIMP is localized on the Z chromosome and is male-specifically expressed in various tissues. Antisense inhibition of BmIMP expression increased female-specific splicing of Bmdsx pre-mRNA. Coimmunoprecipitation and glutathione S-transferase (GST) pulldown analyses demonstrated that BmIMP physically interacts with BmPSI, which has been identified as a factor implicated in the sex-specific splicing of Bmdsx, through the KH domains of BmIMP. The functional consequence of this interaction was examined using RNA mobility shift analysis. BmIMP increased BmPSI-CE1 RNA binding activity by decreasing the rate of BmPSI dissociation from CE1 RNA. Truncation analysis of BmIMP suggested that the KH domains are responsible for enhancing BmPSI-CE1 RNA binding activity. These results suggest that BmIMP may enhance the male-specific splicing of Bmdsx pre-mRNA by increasing RNA binding activity of BmPSI.
Institute of Physical and Chemical Research (RIKEN), Wako, Saitama, Japan. gakyo@riken.jp
Masataka G
MG
Suzuki
Shigeo
S
Imanishi
Naoshi
N
Dohmae
Miwako
M
Asanuma
Shogo
S
Matsumoto
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008969:Molecular Sequence Data; D034622:RNA Interference; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D012727:Sex Characteristics; D014018:Tissue Distribution
C442431:Bmdsx protein, Bombyx mori; D004268:DNA-Binding Proteins; D019476:Insect Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins