title: A1 demonstrates restricted tissue distribution during embryonic development and functions to protect against cell death.
abstract: Members of the bcl-2 gene family are essential regulators of cell survival in a wide range of biological processes. A1, a member of the family, is known to be expressed in certain adult tissues. However, the precise tissue distribution and function of A1 remains poorly understood. We show here that A1 is expressed in multiple tissues during murine embryonic development. In the embryo, A1 was detected first at embryonic day 11.5 in liver, brain, and limbs. At day 13.5 of gestation, A1 expression was observed in the central nervous system, liver, perichondrium, and digital zones of developing limbs in a pattern different from that of bcl-X. In the central nervous system of 15.5-day embryos, A1 was expressed at high levels in the ventricular zone and cortical plate of brain cortex. Significantly, the interdigital zones of limbs and the intermediate region of the developing brain cortex, two sites associated with extensive cell death, were devoid of A1 and bcl-X. The expression of A1 was retained in many adult tissues. To assess the ability of A1 to modulate cell death, stable transfectants expressing different amounts of A1 protein were generated in K562 cells. Expression of A1 was associated with retardation of apoptotic cell death induced by actinomycin D and cycloheximide as well as by okadaic acid. Confocal microscopy showed that the A1 protein was localized to the cytoplasm in a pattern similar to that of Bcl-2. These results demonstrate that the expression of A1 is wider than previously reported in adult tissues. Furthermore, its distribution in multiple tissues of the embryo suggests that A1 plays a role in the regulation of physiological cell death during embryonic development.
authors.affiliation: Servicio de Inmunología, H. U. Marqués de Valdecilla, Instituto Nacional de la Salud, Santander, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Carrió
authors.forename: M
authors.initials: M
authors.lastname: López-Hoyos
authors.forename: J
authors.initials: J
authors.lastname: Jimeno
authors.forename: M A
authors.initials: MA
authors.lastname: Benedict
authors.forename: R
authors.initials: R
authors.lastname: Merino
authors.forename: A
authors.initials: A
authors.lastname: Benito
authors.forename: J L
authors.initials: JL
authors.lastname: Fernández-Luna
authors.forename: G
authors.initials: G
authors.lastname: Núñez
authors.forename: J A
authors.initials: JA
authors.lastname: García-Porrero
authors.forename: J
authors.initials: J
authors.lastname: Merino
mesh_terms: D000818:Animals; D016923:Cell Death / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000494:pharmacology; D005314:Embryonic and Fetal Development / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins; D017403:In Situ Hybridization; D051379:Mice; D015778:Minor Histocompatibility Antigens; D009928:Organ Specificity; D015388:Organelles / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis / Q000494:pharmacology; D011519:Proto-Oncogenes; D051818:Replication Protein C; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D051020:bcl-X Protein
chemical_list: C096816:BCL2-related protein A1; C494812:Bcl2l1 protein, mouse; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; C096063:MATA1 protein, S cerevisiae; D015778:Minor Histocompatibility Antigens; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D051020:bcl-X Protein; D051818:Replication Protein C