title: BAC-mediated transgenic expression of fluorescent autophagic protein Beclin 1 reveals a role for Beclin 1 in lymphocyte development.
abstract: Beclin 1/Atg6 is an essential component of the evolutionary conserved PtdIns(3)-kinase (Vps34) protein complex that regulates macroautophagy (autophagy) in eukaryotic cells and also interacts with antiapoptotic Bcl-2 family members, Bcl-2, and Bcl-x(L). To elucidate the physiological function of Beclin 1, we generated transgenic mice producing a green fluorescent Beclin 1 protein (Beclin 1-GFP) under Beclin 1 endogenous regulation. The beclin 1-GFP transgene is functional because it completely rescues early embryonic lethality in beclin 1-deficient mice. The transgenic mice appear normal, with undetected change in basal autophagy levels in different tissues, despite the additional expression of functional Beclin 1-GFP. Staining of Beclin 1-GFP shows mostly diffuse cytoplasmic distribution in various tissues. Detailed analysis of the transgene expression by flow cytometry reveals a Bcl-2-like biphasic expression pattern in developing T and B cells, as well as differential regulation of expression in mature versus immature thymocytes following in vitro stimulation. Moreover, thymocytes expressing high Beclin 1-GFP levels appear increasingly sensitive to glucocorticoid-induced apoptosis in vitro. Our results, therefore, support a role for Beclin 1 in lymphocyte development involving cross talk between autophagy and apoptosis.
authors.affiliation: Department of Biology, York College, The City University of New York, Jamaica, NY, USA. iarsov@york.cuny.edu
authors.forename: I
authors.initials: I
authors.lastname: Arsov
authors.forename: X
authors.initials: X
authors.lastname: Li
authors.forename: G
authors.initials: G
authors.lastname: Matthews
authors.forename: J
authors.initials: J
authors.lastname: Coradin
authors.forename: B
authors.initials: B
authors.lastname: Hartmann
authors.forename: A K
authors.initials: AK
authors.lastname: Simon
authors.forename: S C
authors.initials: SC
authors.lastname: Sealfon
authors.forename: Z
authors.initials: Z
authors.lastname: Yue
mesh_terms: D000818:Animals; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D001343:Autophagy; D001402:B-Lymphocytes / Q000276:immunology; D000071186:Beclin-1; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D022202:Chromosomes, Artificial, Bacterial; D003907:Dexamethasone / Q000494:pharmacology; D005456:Fluorescent Dyes / Q000032:analysis; D005938:Glucocorticoids / Q000494:pharmacology; D049452:Green Fluorescent Proteins / Q000032:analysis / Q000235:genetics; D008213:Lymphocyte Activation; D051379:Mice; D008822:Mice, Transgenic; D011506:Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D013601:T-Lymphocytes / Q000276:immunology*; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology
chemical_list: D051017:Apoptosis Regulatory Proteins; D000071186:Beclin-1; C115010:Becn1 protein, mouse; D005456:Fluorescent Dyes; D005938:Glucocorticoids; D011506:Proteins; D049452:Green Fluorescent Proteins; D003907:Dexamethasone