title: Characterization of in vivo Dlg1 deletion on T cell development and function.
abstract: BACKGROUND
  The polarized reorganization of the T cell membrane and intracellular signaling molecules in response to T cell receptor (TCR) engagement has been implicated in the modulation of T cell development and effector responses. In siRNA-based studies Dlg1, a MAGUK scaffold protein and member of the Scribble polarity complex, has been shown to play a role in T cell polarity and TCR signal specificity, however the role of Dlg1 in T cell development and function in vivo remains unclear.
  
  
  RESULTS
  Here we present the combined data from three independently-derived dlg1-knockout mouse models; two germline deficient knockouts and one conditional knockout. While defects were not observed in T cell development, TCR-induced early phospho-signaling, actin-mediated events, or proliferation in any of the models, the acute knockdown of Dlg1 in Jurkat T cells diminished accumulation of actin at the IS. Further, while Th1-type cytokine production appeared unaffected in T cells derived from mice with a dlg1 germline-deficiency, altered production of TCR-dependent Th1 and Th2-type cytokines was observed in T cells derived from mice with a conditional loss of dlg1 expression and T cells with acute Dlg1 suppression, suggesting a differential requirement for Dlg1 activity in signaling events leading to Th1 versus Th2 cytokine induction. The observed inconsistencies between these and other knockout models and siRNA strategies suggest that 1) compensatory upregulation of alternate gene(s) may be masking a role for dlg1 in controlling TCR-mediated events in dlg1 deficient mice and 2) the developmental stage during which dlg1 ablation begins may control the degree to which compensatory events occur.
  
  
  CONCLUSIONS
  These findings provide a potential explanation for the discrepancies observed in various studies using different dlg1-deficient T cell models and underscore the importance of acute dlg1 ablation to avoid the upregulation of compensatory mechanisms for future functional studies of the Dlg1 protein.
authors.affiliation: Department of Microbiology, Immunology, and Molecular Genetics, University of California Los Angeles, Los Angeles, California, USA.
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Humphries
authors.forename: Meredith H
authors.initials: MH
authors.lastname: Shaffer
authors.forename: Faruk
authors.initials: F
authors.lastname: Sacirbegovic
authors.forename: Tamar
authors.initials: T
authors.lastname: Tomassian
authors.forename: Kerrie-Ann
authors.initials: KA
authors.lastname: McMahon
authors.forename: Patrick O
authors.initials: PO
authors.lastname: Humbert
authors.forename: Oscar
authors.initials: O
authors.lastname: Silva
authors.forename: June L
authors.initials: JL
authors.lastname: Round
authors.forename: Kogo
authors.initials: K
authors.lastname: Takamiya
authors.forename: Richard L
authors.initials: RL
authors.lastname: Huganir
authors.forename: Janis K
authors.initials: JK
authors.lastname: Burkhardt
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Russell
authors.forename: M Carrie
authors.initials: MC
authors.lastname: Miceli
mesh_terms: D000199:Actins / Q000235:genetics / Q000276:immunology; D000818:Animals; D002450:Cell Communication / Q000235:genetics; D002454:Cell Differentiation; D016207:Cytokines / Q000096:biosynthesis / Q000276:immunology; D000074288:Discs Large Homolog 1 Protein; D018507:Gene Expression Regulation, Developmental; D005818:Genetic Engineering; D018095:Germ-Line Mutation; D008213:Lymphocyte Activation; D051379:Mice; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins / Q000172:deficiency / Q000235:genetics* / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000235:genetics* / Q000276:immunology; D000074407:SAP90-PSD95 Associated Proteins; D015398:Signal Transduction; D018417:Th1 Cells / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D058408:Th1-Th2 Balance; D018418:Th2 Cells / Q000166:cytology / Q000276:immunology / Q000378:metabolism*
chemical_list: D000199:Actins; D016207:Cytokines; D000074288:Discs Large Homolog 1 Protein; C000614189:Dlg1 protein, mouse; D009419:Nerve Tissue Proteins; D011948:Receptors, Antigen, T-Cell; D000074407:SAP90-PSD95 Associated Proteins