title: Chip physically interacts with Notch and their stoichiometry is critical for Notch function in wing development and cell proliferation in Drosophila.
abstract: BACKGROUND
  Notch signaling plays a fundamental role both in metazoan cell fate determination and in the establishment of distinct developmental cell lineages. In a yeast two-hybrid screen, we identified Chip as a binding partner of Notch. Thus, we investigated the functional significance of Notch and Chip interactions.
  
  
  METHODS
  Co-immunoprecipitation and GST pull-down experiments confirmed the physical interaction between Notch and Chip. Immunostaining revealed that Chip and Notch-intracellular domain (Notch-ICD) co-localized in cell nuclei. Loss-of-function and gain-of-function analyses of Chip were carried out using FLP/FRT and GAL4-UAS systems, respectively. Immunostaining and real-time PCR were performed to analyze the role of Chip on Notch-induced cell proliferation.
  
  
  RESULTS
  Here, we report transcriptional cofactor Chip as a novel binding partner of Notch. Chip and Notch also showed strong genetic interactions, and Chip mutant clones in the dorsal compartment induced ectopic wing margins by ectopic expression of Notch and its targets, Wg and Cut. Our analyses revealed that stoichiometry of Notch and Chip is critical at the dorso-ventral (DV) boundary for wing margin formation. In addition, overexpression of Chip can rescue Notch-induced cell proliferation in larval imaginal discs.
  
  
  CONCLUSIONS
  Our results indicate that Notch function in the DV boundary area is presumably dependent on Notch-Chip heterodimer formation. In addition, overexpression of Chip can rescue Notch-induced cell proliferation, presumably through titration of overexpressed Notch-ICD by excess Chip molecules.
  
  
  CONCLUSIONS
  The present study reveals that Chip is a novel interacting partner of Notch and it plays a major role in Notch-induced DV margin formation and cell proliferation.
authors.affiliation: Department of Molecular and Human Genetics, Banaras Hindu University, Varanasi 221 005, India.
authors.forename: Nalani
authors.initials: N
authors.lastname: Sachan
authors.affiliation: Department of Molecular and Human Genetics, Banaras Hindu University, Varanasi 221 005, India.
authors.forename: Abhinava K
authors.initials: AK
authors.lastname: Mishra
authors.affiliation: Department of Molecular and Human Genetics, Banaras Hindu University, Varanasi 221 005, India.
authors.forename: Mousumi
authors.initials: M
authors.lastname: Mutsuddi
authors.affiliation: Department of Molecular and Human Genetics, Banaras Hindu University, Varanasi 221 005, India. Electronic address: ashim04@gmail.com.
authors.forename: Ashim
authors.initials: A
authors.lastname: Mukherjee
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D029721:Drosophila Proteins / Q000502:physiology*; D004331:Drosophila melanogaster / Q000196:embryology*; D018507:Gene Expression Regulation, Developmental; D009687:Nuclear Proteins / Q000502:physiology*; D051880:Receptors, Notch / Q000502:physiology*; D014921:Wings, Animal / Q000196:embryology*
chemical_list: C108740:Chi protein, Drosophila; D029721:Drosophila Proteins; C497759:N protein, Drosophila; D009687:Nuclear Proteins; D051880:Receptors, Notch
keywords: Chip; Drosophila; Notch; cell proliferation; dorso-ventral boundary