Stat3 controls cell death during mammary gland involution by regulating uptake of milk fat globules and lysosomal membrane permeabilization.

We have previously demonstrated that Stat3 regulates lysosomal-mediated programmed cell death (LM-PCD) during mouse mammary gland involution in vivo. However, the mechanism that controls the release of lysosomal cathepsins to initiate cell death in this context has not been elucidated. We show here that Stat3 regulates the formation of large lysosomal vacuoles that contain triglyceride. Furthermore, we demonstrate that milk fat globules (MFGs) are toxic to epithelial cells and that, when applied to purified lysosomes, the MFG hydrolysate oleic acid potently induces lysosomal leakiness. Additionally, uptake of secreted MFGs coated in butyrophilin 1A1 is diminished in Stat3-ablated mammary glands and loss of the phagocytosis bridging molecule MFG-E8 results in reduced leakage of cathepsins in vivo. We propose that Stat3 regulates LM-PCD in mouse mammary gland by switching cellular function from secretion to uptake of MFGs. Thereafter, perturbation of lysosomal vesicle membranes by high levels of free fatty acids results in controlled leakage of cathepsins culminating in cell death.This work was supported by a grant from the Medical Research Council programme grant no. MR/J001023/1 (T.J.S. and B. L-L.) and a Cancer Research UK Cambridge Cancer Centre PhD studentship (H.K.R.).This is the accepted manuscript. The final version is available from Nature Publishing at http://www.nature.com/ncb/journal/vaop/ncurrent/full/ncb3043.html

Depressão resistente a tratamento: uma revisão das estratégias farmacológicas de potencialização de antidepressivos Treatment-resistant depression: review of pharmacologic antidepressant strategies

OBJETIVO: Fazer uma revisão sobre oito estratégias farmacológicas de potencialização de antidepressivos na DRT. MÉTODOS: Fez-se um levantamento bibliográfico de 1990 até janeiro de 2006, nas bases eletrônicas de busca Medline, LILACS e da Biblioteca Cochrane, utilizando-se os termos de busca treatment, resistant, refractory e depression e os descritores depression, drug resistance e augmentation, incluindo apenas ensaios controlados duplo-cegos. Foi consultada a referência dos artigos para obtenção de ensaios realizados em data anterior a 1990 e artigos originais de valor histórico. RESULTADOS: Foram encontrados 17 estudos duplo-cegos com o lítio, seis com o hormônio tireoidiano, dois com a buspirona, seis com o pindolol, um com a carbamazepina, dois com a lamotrigina e quatro com a olanzapina. Foram favoráveis à potencialização 41,2% dos ensaios com lítio; 60% daqueles com hormônio tireoidiano e antidepressivos tricíclicos e nenhum com hormônio tireoidiano e inibidores seletivos da recaptação da serotonina (ISRS); 50% dos com pindolol; 100% dos ensaios com carbamazepina e 40% daqueles com olanzapina. Nenhum dos estudos com a buspirona foi favorável. No único estudo com lamotrigina não houve eficácia de tratamento na avaliação pelo critério principal, mas superioridade ao placebo em critérios secundários. CONCLUSÃO: Na DRT há evidência de eficácia apenas em relação ao lítio na potencialização de várias classes de antidepressivos e ao hormônio tireoidiano na potencialização de tricíclicos. A olanzapina foi razoavelmente estudada e sua eficácia não foi estabelecida. Os poucos estudos realizados com a buspirona e o pindolol não comprovaram sua eficácia. A carbamazepina foi muito pouco estudada, e a lamotrigina ainda não foi adequadamente avaliada.<br>OBJECTIVE: The aim of this study is to review eight pharmacologic antidepressant augmentation strategies in TRD. METHODS: Database search on Medline, LILACS and Cochrane Library, from 1990 to June 2006 using the words treatment, resistant, refractory, depression and the medical subject headings depression, drug resistance and augmentation. Double-blind controlled trials and reviews were included. We also consulted reference of the articles in order to obtain studies and original articles of historical value from before 1990. RESULTS: There were 17 double-blind trials with lithium, six with thyroid hormone, two with buspirone, six with pindolol one with carbamazepine, two with lamotrigine and four with olanzapine. Forty-one percent of the trials with lithium, 60% of those with thyroid hormone and tricyclics, 0% of the ones with thyroid hormone and selective serotonin reuptake inhibitors (SSRI), 50% of those with pindolol, 100% of those with carbamazepine and 40% of the ones with olanzapine were favorable. No trials with buspirone were favorable. The only trial with lamotrigine did not show efficacy using the main outcome measures. Otherwise, there was superiority over placebo on secondary measures. CONCLUSION: Only lithium and thyroid hormone showed efficacy as antidepressant augmentation strategies for TRD. Olanzapine was reasonably studied and did not prove its efficacy. There were just a few studies on buspirone and pindolol and they were not favorable to them. Carbamazepine was studied very little. Lamotrigine was not adequately evaluated