RESUMO
Eukaryotic cells have evolved signalling pathways that allow adaptation to harmful conditions that disrupt endoplasmic reticulum (ER) homeostasis. When the function of the ER is compromised in a condition known as ER stress, the cell triggers the unfolded protein response (UPR) in order to restore ER homeostasis. Accumulation of misfolded proteins due to stress conditions activates the UPR pathway. In mammalian cells, the UPR is composed of three branches, each containing an ER sensor (PERK, ATF6 and IRE1). However, in yeast species, the only sensor present is the inositol-requiring enzyme Ire1. To cope with unfolded protein accumulation, Ire1 triggers either a transcriptional response mediated by a transcriptional factor that belongs to the bZIP transcription factor family or an mRNA degradation process. In this review, we address the current knowledge of the UPR pathway in several yeast species: Saccharomyces cerevisiae, Schizosaccharomyces pombe, Candida glabrata, Cryptococcus neoformans, and Candida albicans. We also include unpublished data on the UPR pathway of the budding yeast Kluyveromyces lactis. We describe the basic components of the UPR pathway along with similarities and differences in the UPR mechanism that are present in these yeast species.
RESUMO
Arabidopsis has 12 histone acetyltransferases grouped in four families: the GNAT/HAG, the MYST/HAM, the p300/CBP/HAC and the TAFII250/HAF families. We previously showed that ham1 and ham2 mutants accumulated higher damaged DNA after UV-B exposure than WT plants. In contrast, hag3 RNA interference transgenic plants showed less DNA damage and lower inhibition of plant growth by UV-B, and increased levels of UV-B-absorbing compounds. These results demonstrated that HAM1, HAM2, and HAG3 participate in UV-B-induced DNA damage repair and signaling. In this work, to further explore the role of histone acetylation in UV-B responses, a putative function of other acetyltransferases of the HAC and the HAF families was analyzed. Neither HAC nor HAF acetyltrasferases participate in DNA damage and repair after UV-B radiation in Arabidopsis. Despite this, haf1 mutants presented lower inhibition of leaf and root growth by UV-B, with altered expression of E2F transcription factors. On the other hand, hac1 plants showed a delay in flowering time after UV-B exposure and changes in FLC and SOC1 expression patterns. Our data indicate that HAC1 and HAF1 have crucial roles for in UV-B signaling, confirming that, directly or indirectly, both enzymes also have a role in UV-B responses.
RESUMO
The typical characteristics of mesenchymal stem cells (MSCs) can be affected by inflammatory microenvironment; however, the exact contribution of HTLV-1 to MSC dysfunction remains to be elucidated. In this study, we demonstrated that MSC cell surface molecules VCAM-1 and ICAM-1 are upregulated by contact with HTLV-1, and HLA-DR was most highly expressed in MSCs co-cultured with MT2 cells. The expression levels of VCAM-1 and HLA-DR were increased in MSCs cultured in the presence of PBMCs isolated from HTLV-1-infected symptomatic individuals compared with those cultured with cells from asymptomatic infected individuals or healthy subjects. HTLV-1 does not impair the MSC differentiation process into osteocytes and adipocytes. In addition, MSCs were efficiently infected with HTLV-1 in vitro through direct contact with HTLV-1-infected cells; however, cell-free virus particles were not capable of causing infection. In summary, HTLV-1 can alter MSC function, and this mechanism may contribute to the pathogenesis of this viral infection.
Assuntos
Infecções por HTLV-I/virologia , Vírus Linfotrópico T Tipo 1 Humano/fisiologia , Células-Tronco Mesenquimais/virologia , Diferenciação Celular , Células Cultivadas , Infecções por HTLV-I/genética , Infecções por HTLV-I/imunologia , Infecções por HTLV-I/fisiopatologia , Humanos , Molécula 1 de Adesão Intercelular/genética , Molécula 1 de Adesão Intercelular/imunologia , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/imunologia , Fenótipo , Molécula 1 de Adesão de Célula Vascular/genética , Molécula 1 de Adesão de Célula Vascular/imunologiaRESUMO
OBJETIVO: O objetivo deste estudo foi avaliar pacientes com HAC clássica antes e após tratamento com glicocorticoides e/ou mineralocorticoides e comparar o perfil metabólico entre o grupo bem controlado (BC) e mal controlado (MC). SUJEITOS E MÉTODOS: Foram selecionados pacientes recém-diagnosticados e pacientes em acompanhamento por HAC, forma clássica, em uso regular ou não de glicocorticoides/mineralocorticoides do Serviço de Genética do Hupes-UFBA, atendidos de março/2004 a maio/2006. Todos os pacientes foram submetidos a avaliação clínica detalhada e exames laboratoriais (glicemia, sódio e potássio, colesterol total, HDL, LDL, triglicerídeos, ácido úrico, leptina, 17-hidroxiprogesterona, testosterona total, peptídeo C e insulina). Os pacientes com valores normais de andrógenos foram classificados como bem controlados (BC) e os com valores elevados de andrógenos em uso ou não de glicocorticoides/mineralocorticoides foram classificados como mal controlados (MC). RESULTADOS: Foram estudados 41 pacientes com HAC: 11 no grupo BC e 30 no grupo MC. Leptina e LDL colesterol estavam mais elevados no grupo BC que no MC (p < 0,05). Valores de ácido úrico eram menores no grupo BC quando comparados com MC (p < 0,05). CONCLUSÃO: O controle adequado da HAC com glicocorticoides parece seguro, pois está associado a alterações discretas no perfil lipídico e da leptina. Não observamos outras alterações metabólicas associadas ao uso de glicocorticoides. O motivo para o menor valor de ácido úrico encontrado nos pacientes com HAC bem controlada não é conhecido e deve ser mais bem estudado.
OBJECTIVE: The objective of this study was to evaluate patients with classic CAH before and after treatment with glucocorticoids/mineralocorticoid and compare the metabolic profile of the well controlled (WC) and poorly controlled (PC) group. SUBJECTS AND METHODS: We selected newly diagnosed patients and patients monitored for CAH, classical form, regularly using or not glucocorticoids/mineralocorticoid in the Genetics Service Hupes-UFBA, seen from March/2004 to May/2006. All patients underwent detailed clinical evaluation and laboratory tests (glucose, sodium and potassium; total cholesterol, HDL, LDL, triglycerides and uric acid; leptin, 17-hydroxyprogesterone, total testosterone, C peptide, and insulin). Patients with normal androgens were classified as well controlled (WC), and those with high levels of androgens either using or not glucocorticoids/mineralocorticoids were classified as poorly controlled (PC). RESULTS: We studied 41 patients with CAH: 11 in the WC group and 30 in PC group. Leptin and LDL cholesterol levels were higher in WC than in the PC group (p < 0.05). Uric acid values were lower in WC compared with the PC group (p < 0.05). CONCLUSION: Adequate control of CAH with steroids seems safe, as it is associated with only mild changes in lipid profile and leptin values. No other metabolic abnormality was associated with glucocorticoid use. The reason for lower uric acid levels found in WC CAH patients is unknown and should be further studied.