The interaction and colocalization of Sam68 with the splicing-associated factor YT521-B in nuclear dots is regulated by the Src family kinase p59(fyn).
Alternative pre-mRNA splicing patterns can change an extracellular stimulus, but the signaling pathways leading to these changes are still poorly characterized. Here, we describe a tyrosine-phosphorylated nuclear protein, YT521-B, and show that it interacts with the nuclear transcriptosomal component scaffold attachment factor B, and the 68-kDa Src substrate associated during mitosis, Sam68. Northern blot analysis demonstrated ubiquitous expression, but detailed RNA in situ analysis revealed cell type specificity in the brain. YT521-B protein is localized in the nucleoplasm and concentrated in 5-20 large nuclear dots. Deletion analysis demonstrated that the formation of these dots depends on the presence of the amino-terminal glutamic acid-rich domain and the carboxyl-terminal glutamic acid/arginine-rich region. We show that the latter comprises an important protein-protein interaction domain. The Src family kinase p59(fyn)-mediated tyrosine phosphorylation of Sam68 negatively regulates its association with YT521-B, and overexpression of p59(fyn) dissolves nuclear dots containing YT521-B. In vivo splicing assays demonstrated that YT521-B modulates alternative splice site selection in a concentration-dependent manner. Together, our data indicate that YT521-B and Sam68 may be part of a signal transduction pathway that influences splice site selection.
Hartmann
A M
AM
Max-Planck-Institut of Neurobiology, Max-Planck-Institut of Biochemistry, D-82152 Martinsried, Germany.
Nayler
O
O
Schwaiger
F W
FW
Obermeier
A
A
Stamm
S
S
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000378:metabolism; D002460:Cell Line; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins; D005656:Fungal Proteins / Q000378:metabolism; D006801:Humans; D017403:In Situ Hybridization; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051076:Proto-Oncogene Proteins c-fyn; D012322:RNA Precursors / Q000235:genetics; D012326:RNA Splicing / Q000235:genetics*; D000072260:RNA Splicing Factors; D016601:RNA-Binding Proteins / Q000378:metabolism*; D051381:Rats; D017384:Sequence Deletion; D000068103:Serine-Arginine Splicing Factors; D015398:Signal Transduction; D014162:Transfection; D015003:Yeasts; D019061:src-Family Kinases / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C489559:KHDRBS1 protein, human; D009419:Nerve Tissue Proteins; D011518:Proto-Oncogene Proteins; D012322:RNA Precursors; D000072260:RNA Splicing Factors; D016601:RNA-Binding Proteins; C490769:YTHDC1 protein, human; C490768:Ythdc1 protein, rat; D000068103:Serine-Arginine Splicing Factors; C494957:FYN protein, human; C494961:Fyn protein, rat; D051076:Proto-Oncogene Proteins c-fyn; D019061:src-Family Kinases