RESUMO
Genetic lesions and other regulatory events lead to silencing of the 13q14 locus in a majority of chronic lymphocytic leukemia (CLL) patients. This locus encodes a pair of critical proapoptotic microRNAs, miR-15a/16-1. Decreased levels of miR-15a/16-1 are critical for the increased survival exhibited by CLL cells. Similarly, in a de novo murine model of CLL, the NZB strain, germline-encoded regulation of the syntenic region resulted in decreased miR-15a/16-1. In this paper, we have identified additional molecular mechanisms regulating miR-15a/16-1 levels and have shown that the transcription factor BSAP (B-cell-specific activator protein) directly interacts with Dleu2, the host gene containing the miR-15a/16-1 loci, and by negative regulation of the Dleu2 promoter, results in repression of miR-15a/16-1 expression. CLL patient B-cell expression levels of BSAP were increased compared with control sources of B cells. With the use of small interfering RNA-mediated repression, the levels of BSAP were decreased in vitro in the NZB-derived malignant B-1 cell line, LNC, and in ex vivo CLL patient peripheral blood mononuclear cells (PBMCs). BSAP knockdown led to an increase in the expression of miR-15a/16-1 and an increase in apoptosis, and a cell cycle arrest in both the cell line and patient PBMCs. Moreover, using Dleu2 promoter analysis by chromatin immunoprecipitation assay, we have shown that BSAP directly interacts with the Dleu2 promoter. Derepression of the Dleu2 promoter via inhibition of histone deacetylation combined with BSAP knockdown increased miR-15a/16-1 expression, and also increased malignant B-cell death. In summary, therapy targeting enhanced host gene Dleu2 transcription may augment CLL therapy.
Assuntos
Leucemia Linfocítica Crônica de Células B/genética , MicroRNAs/genética , Proteínas Supressoras de Tumor/genética , Animais , Apoptose/genética , Linfócitos B/metabolismo , Pontos de Checagem do Ciclo Celular/genética , Morte Celular/genética , Linhagem Celular Tumoral , Regulação Leucêmica da Expressão Gênica , Humanos , Leucemia Linfocítica Crônica de Células B/sangue , Leucemia Linfocítica Crônica de Células B/metabolismo , Leucemia Linfocítica Crônica de Células B/patologia , Leucócitos Mononucleares/metabolismo , Camundongos , Camundongos Endogâmicos NZB , MicroRNAs/metabolismo , Fator de Transcrição PAX5/genética , Fator de Transcrição PAX5/metabolismo , Regiões Promotoras Genéticas , RNA Longo não Codificante , Transcrição Gênica , Transferases , Proteínas Supressoras de Tumor/metabolismoRESUMO
Genetic diversity and phylogenetic relationships among 22 local cowpea (Vigna unguiculata) varieties and inbred lines collected throughout Senegal were evaluated using simple sequence repeat molecular markers. A set of 49 primer combinations were developed from cowpea genomic/expressed sequence tags and evaluated for their ability to detect polymorphisms among the various cowpea genotypes. Forty-four primer combinations detected polymorphisms, with the remaining five primer sets failing to yield PCR amplification products. From one to 16 alleles were found among the informative primer combinations; their frequencies ranged from 0.60 to 0.95 (mean = 0.79). The genetic diversity of the sample varied from 0.08 to 0.42 (mean = 0.28). The polymorphic information content ranged from 0.08 to 0.33 (mean = 0.23). The local varieties clustered in the same group, except 53-3, 58-53, and 58-57; while Ndoute yellow pods, Ndoute violet pods and Baye Ngagne were in the second group. The photosensitive varieties (Ndoute yellow pods and Ndoute violet pods) were closely clustered in the second group and so were inbred line Mouride and local cultivar 58-57, which is also one of the parents for inbred line Mouride. These molecular markers could be used for selection and identification of elite varieties for cowpea improvement and germplasm management in Senegal.
