title: Mad3 negatively regulates B cell differentiation in the spleen by inducing Id2 expression.
abstract: Immature B cells migrate to the spleen where they differentiate into mature cells. This final maturation step is crucial to enable B cells to become responsive to antigens and to participate in the immune response. Previously, we showed that Id2 acts as a negative regulator of the differentiation of immature B cells occurring in the spleen. Id2 expression has been found to depend on Myc-Max-Mad transcriptional complexes in mammary epithelial cells. Nearly all studies to date have shown that Mad proteins inhibit proliferation, presumably by antagonizing the function of Myc proteins. In the current study, we followed the Mad family members during peripheral B cell differentiation. We show that Mad3 actively regulates B cell differentiation. Our results demonstrate that high expression levels of Mad3 in immature B cells induce Id2 expression, which inhibits transcription of genes essential for B cell differentiation. During their differentiation to mature cells, B cells reduce their Mad3 expression, enabling the maturation process to occur.
authors.affiliation: Department of Immunology, The Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Yael
authors.initials: Y
authors.lastname: Gore
authors.forename: Frida
authors.initials: F
authors.lastname: Lantner
authors.forename: Gili
authors.initials: G
authors.lastname: Hart
authors.forename: Idit
authors.initials: I
authors.lastname: Shachar
mesh_terms: D000818:Animals; D000944:Antigens, Differentiation, B-Lymphocyte / Q000235:genetics / Q000378:metabolism; D001402:B-Lymphocytes / Q000166:cytology / Q000502:physiology*; D002454:Cell Differentiation / Q000502:physiology*; D000949:Histocompatibility Antigens Class II / Q000235:genetics / Q000378:metabolism; D006801:Humans; D051797:Inhibitor of Differentiation Protein 2 / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D016376:Oligonucleotides, Antisense / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D013154:Spleen / Q000166:cytology*
chemical_list: D000944:Antigens, Differentiation, B-Lymphocyte; D000949:Histocompatibility Antigens Class II; C497452:Idb2 protein, mouse; D051797:Inhibitor of Differentiation Protein 2; C472089:Mxd3 protein, mouse; D016376:Oligonucleotides, Antisense; D012097:Repressor Proteins; C045084:invariant chain