title: Microarray analysis of Lyn-deficient B cells reveals germinal center-associated nuclear protein and other genes associated with the lymphoid germinal center.
abstract: Lyn is the only member of the Src family expressed in DT40 B cells, which provide a unique model to study the singular contribution of this protein tyrosine kinase (PTK) family to cell signaling. In these cells, gene ablation of Lyn leads to defective B cell receptor signaling. Complementary DNA array analysis of Lyn-deficient DT40 cells shows that the absence of Lyn leads to down-regulation of numerous genes encoding proteins involved in B cell receptor signaling, proliferation, control of transcription, immunity/inflammation response, and cytoskeletal organization. Most of these expression changes have not been previously associated with Lyn PTK signaling. They include alterations in mRNA levels of germinal center-associated nuclear protein (germinal center-associated DNA primase) (GANP), CD74, CD22, NF-kappaB, elongation factor 1alpha, CD79b, octamer binding factor 1, Ig H chain, stathmin, and gamma-actin. Changes in GANP expression were also confirmed in Lyn-deficient mice, suggesting that Lyn PTK has a unique function not compensated for by other Src kinases. Because Lyn-deficient mice have impaired development of germinal centers in spleen, the decreased expression of GANP in the Lyn-deficient DT40 cell line and Lyn-deficient mice suggests that Lyn controls the formation and proliferation of germinal centers via GANP. GANP promoter activity was higher in wild-type vs Lyn-deficient cells. Mutation of the PU.1 binding site reduced activity in wild-type cells and had no effect in Lyn-deficient cells. The presence of Lyn enhanced PU.1 expression in a Northern blot. Thus, the following new signaling pathway has been described: Lyn-->PU.1-->GANP.
authors.affiliation: Department of Pediatrics, University of Pittsburgh, School of Medicine, Children's Hospital of Pittsburgh, Pittsburgh, PA 15213, USA.
authors.forename: Zeljka Korade
authors.initials: ZK
authors.lastname: Mirnics
authors.forename: Eva
authors.initials: E
authors.lastname: Caudell
authors.forename: YanHua
authors.initials: Y
authors.lastname: Gao
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Kuwahara
authors.forename: Nobuo
authors.initials: N
authors.lastname: Sakaguchi
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Kurosaki
authors.forename: Joan
authors.initials: J
authors.lastname: Burnside
authors.forename: Károly
authors.initials: K
authors.lastname: Mirnics
authors.forename: Seth J
authors.initials: SJ
authors.lastname: Corey
mesh_terms: D000818:Animals; D016175:B-Lymphocyte Subsets / Q000201:enzymology* / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D002455:Cell Division / Q000235:genetics / Q000276:immunology; D045744:Cell Line, Tumor; D002645:Chickens; D020869:Gene Expression Profiling / Q000379:methods; D018858:Germinal Center / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D010750:Phosphoproteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology; D013154:Spleen / Q000166:cytology / Q000201:enzymology / Q000276:immunology; D015534:Trans-Activators / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology; D019061:src-Family Kinases / Q000172:deficiency* / Q000235:genetics* / Q000502:physiology; D000099232:Proto-Oncogene Protein Spi-1
chemical_list: D009687:Nuclear Proteins; D010750:Phosphoproteins; D011518:Proto-Oncogene Proteins; D015534:Trans-Activators; D019061:src-Family Kinases; D000099232:Proto-Oncogene Protein Spi-1; C481510:GANP protein, mouse; C060902:lyn protein-tyrosine kinase