RESUMEN
Aberrant expression of special AT-rich binding protein 1 (SATB1), a global genomic organizer, has been associated with various cancers, which raises the question of how higher-order chromatin structure contributes to carcinogenesis. Disruption of apoptosis is one of the hallmarks of cancer. We previously demonstrated that SATB1 mediated specific long-range chromosomal interactions between the mbr enhancer located within 3'-UTR of the BCL2 gene and the promoter to regulate BCL2 expression during early apoptosis. In the present study, we used chromosome conformation capture (3C) assays and molecular analyses to further investigate the function of the SATB1-mediated higher-order chromatin structure in co-regulation of the anti-apoptotic BCL2 gene and the pro-apoptotic NOXA gene located 3.4Mb downstream on Chromosome 18. We demonstrated that the mbr enhancer spatially juxtaposed the promoters of BCL2 and NOXA genes through SATB1-mediated chromatin-loop in Jurkat cells. Decreased SATB1 levels switched the mbr-BCL2 loop to mbr-NOXA loop, and thus changed expression of these two genes. The SATB1-mediated dynamic switch of the chromatin loop structures was essential for the cooperative expression of the BCL2 and NOXA genes in apoptosis. Notably, the role of SATB1 was specific, since inhibition of SATB1 degradation by caspase-6 inhibitor or caspase-6-resistant SATB1 mutant reversed expression of BCL-2 and NOXA in response to apoptotic stimulation. This study reveals the critical role of SATB1-organized higher-order chromatin structure in regulating the dynamic equilibrium of apoptosis-controlling genes with antagonistic functions and suggests that aberrant SATB1 expression might contribute to cancer development by disrupting the co-regulated genes in apoptosis pathways.
Asunto(s)
Apoptosis , Cromatina/metabolismo , Proteínas de Unión a la Región de Fijación a la Matriz/metabolismo , Proteínas Proto-Oncogénicas c-bcl-2/genética , Cromatina/química , Cromatina/genética , Elementos de Facilitación Genéticos/genética , Regulación de la Expresión Génica , Humanos , Células Jurkat , Regiones Promotoras Genéticas/genéticaRESUMEN
The 279-bp major breakpoint region (mbr) within the 3'-untranslated region (3'-UTR) of the BCL2 gene is a binding site of special AT-rich sequence binding protein 1 (SATB1) that is well known to participate in the long-range regulation of gene transcription. Our previous studies have revealed that the mbr could regulate BCL2 transcription over a 200-kb distance and this regulatory function was closely related to SATB1. This study is to explore the underlying mechanism and its relevance to cellular apoptosis. With chromosome conformation capture (3C) and chromatin immunoprecipitation (ChIP) assays we demonstrated that the mbr could physically interact with BCL2 promoter through SATB1-mediated chromatin looping, which was required for epigenetic modifications of the promoter, CREB accessibility and high expression of the BCL2 gene. During early apoptosis, SATB1 was a key regulator of BCL2 expression. Inhibition of SATB1 cleavage by treatment of cells with a caspase-6 inhibitor or overexpression of mutant SATB1 that was resistant to caspase-6, inhibited disassembly of the SATB1-mediated chromatin loop and restored the BCL2 mRNA level in Jurkat cells. These data revealed a novel mechanism of BCL2 regulation and mechanistically link SATB1-mediated long-range interaction with the regulation of a gene controlling apoptosis pathway for the first time.
Asunto(s)
Regiones no Traducidas 3' , Epigénesis Genética , Proteínas de Unión a la Región de Fijación a la Matriz/metabolismo , Regiones Promotoras Genéticas , Proteínas Proto-Oncogénicas c-bcl-2/genética , Apoptosis , Proteína beta Potenciadora de Unión a CCAAT/metabolismo , Cromosomas/metabolismo , Proteína de Unión a Elemento de Respuesta al AMP Cíclico/metabolismo , Humanos , Células Jurkat , Proteínas de Unión a la Región de Fijación a la Matriz/fisiología , Transcripción Genética , Factores de Transcripción p300-CBP/metabolismoRESUMEN
Reduced glutathione (GSH) , the most abundant non-protein thiol in mammalian cells, exists extensively in the human body and plays a key role in many biological processes, including the synthesis of proteins and DNA and the transport of amino acids, especially in protecting cells against oxidation. GSH also shows its important clinical value in the treatment of many diseases. It has been reported that GSH also widely exists in the male reproductive system and has a therapeutic role in male infertility. The objective of this review is to summarize the distribution of GSH in the male reproductive system and its therapeutic value for male infertility.