title: Weaning induces NOS-2 expression through NF-kappaB modulation in the lactating mammary gland: importance of GSH.
abstract: At the end of lactation the mammary gland undergoes involution, a process characterized by apoptosis of secretory cells and tissue remodelling. To gain insight into this process, we analysed the gene expression profile by oligonucleotide microarrays during lactation and after forced weaning. Up-regulation of inflammatory mediators and acute-phase response genes during weaning was found. Expression of IkappaBalpha (inhibitory kappaBalpha), a protein known to modulate NF-kappaB (nuclear factor-kappaB) nuclear translocation, was significantly up-regulated. On the other hand, there was a time-dependent degradation of IkappaBalpha protein levels in response to weaning, suggesting a role for NF-kappaB. Furthermore, we have demonstrated, using chromatin immunoprecipitation assays, binding of NF-kappaB to the NOS-2 (inducible nitric oxide synthase) promoter at the early onset of events triggered during weaning. The three isoforms of NOS are constitutively present in the lactating mammary gland; however, while NOS-2 mRNA and protein levels and, consequently, NO production are increased during weaning, NOS-3 protein levels are diminished. Western blot analyses have demonstrated that protein nitration is increased in the mammary gland during weaning, but this is limited to a few specific tyrosine-nitrated proteins. Interestingly, inhibition of GSH synthesis at the peak of lactation partially mimics these findings, highlighting the role of NO production and GSH depletion during involution.
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Universidad de Valencia, Avda. Blasco Ibáñez 17, 46010 Valencia, Spain.
authors.forename: Rosa
authors.initials: R
authors.lastname: Zaragozá
authors.forename: Vicente J
authors.initials: VJ
authors.lastname: Miralles
authors.forename: A Diana
authors.initials: AD
authors.lastname: Rus
authors.forename: Concha
authors.initials: C
authors.lastname: García
authors.forename: Rafael
authors.initials: R
authors.lastname: Carmena
authors.forename: Elena R
authors.initials: ER
authors.lastname: García-Trevijano
authors.forename: Teresa
authors.initials: T
authors.lastname: Barber
authors.forename: Federico V
authors.initials: FV
authors.lastname: Pallardó
authors.forename: Luís
authors.initials: L
authors.lastname: Torres
authors.forename: Juan R
authors.initials: JR
authors.lastname: Viña
mesh_terms: D000818:Animals; D015536:Down-Regulation; D004790:Enzyme Induction; D005260:Female; D020869:Gene Expression Profiling; D005978:Glutathione / Q000378:metabolism*; D007774:Lactation / Q000502:physiology*; D008321:Mammary Glands, Animal / Q000201:enzymology / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis / Q000235:genetics*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D021381:Protein Transport; D051381:Rats; D017208:Rats, Wistar; D015854:Up-Regulation; D014886:Weaning
chemical_list: D016328:NF-kappa B; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D005978:Glutathione