title: Multiple Cos2/Ci interactions regulate Ci subcellular localization through microtubule dependent and independent mechanisms.
abstract: The Hedgehog (Hh) family of secreted proteins governs many developmental processes in both vertebrates and invertebrates. In Drosophila, Hh acts by blocking the formation of a truncated repressor form of Cubitus interruptus (Ci) and by stimulating the nuclear translocation and activity of full-length Ci (Ci155). In the absence of Hh, Ci155 is sequestered in the cytoplasm by forming protein complexes with Costal2 (Cos2), Fused (Fu) and Suppressor of Fused [Su(fu)]. How complex formation regulates Ci155 subcellular localization is not clear. We find that Cos2 interacts with two distinct domains of Ci155, an amino (N)-terminal domain (CDN) and a carboxyl (C)-terminal domain (CORD), and Cos2 competes with Su(fu) for binding to the N-terminal region of Ci155. We provide evidence that both N- and C-terminal Cos2 binding domains are involved in the cytoplasmic retention of Ci155 in imaginal discs. Treating imaginal discs with microtubule-destabilizing reagent nocodazole promotes nuclear translocation of Ci155, suggesting that the microtubule network plays an important role in the cytoplasmic retention of Ci155. In addition, we find that adding a nuclear localization signal (NLS) to exposed regions of Ci155 greatly facilitates its nuclear translocation, suggesting that the cytoplasmic retention of Ci155 may also depend on NLS masking.
authors.affiliation: Center for Developmental Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9133, USA.
authors.forename: Gelin
authors.initials: G
authors.lastname: Wang
authors.forename: Jin
authors.initials: J
authors.lastname: Jiang
mesh_terms: D000818:Animals; D003593:Cytoplasm / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004330:Drosophila / Q000254:growth & development / Q000378:metabolism; D029721:Drosophila Proteins / Q000378:metabolism; D016547:Kinesins / Q000378:metabolism*; D007814:Larva / Q000254:growth & development / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism*; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017434:Protein Structure, Tertiary; D014157:Transcription Factors
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D014157:Transcription Factors; C092937:ci protein, Drosophila; C107452:cos protein, Drosophila; C085770:fu protein, Drosophila; D017346:Protein Serine-Threonine Kinases; D016547:Kinesins