RESUMEN
Our understanding of the molecular mechanisms that operate during differentiation of mitotically dividing spermatogonia cells into spermatocytes lags way behind what is known about other differentiating systems. Given the evolutionary conservation of the meiotic process, we screened for mouse proteins that could specifically activate early meiotic promoters in Saccharomyces cerevisiae yeast cells, when fused to the Gal4 activation domain (Gal4AD). Our screen yielded the Aym1 gene that encodes a short peptide of 45 amino acids. We show that a Gal4AD-AYM1 fusion protein activates expression of reporter genes through the promoters of the early meiosis-specific genes IME2 and HOP1, and that this activation is dependent on the DNA-binding protein Ume6. Aym1 is transcribed predominantly in mouse primary spermatocytes and in gonads of female embryos undergoing the corresponding meiotic divisions. Aym1 immunolocalized to nuclei of primary spermatocytes and oocytes and to specific type A spermatogonia cells, suggesting it might play a role in the processes leading to meiotic competence. The potential functional relationship between AYM1 and yeast proteins that regulate expression of early meiotic genes is discussed.
Asunto(s)
Regulación del Desarrollo de la Expresión Génica , Genes Fúngicos , Meiosis , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/fisiología , Secuencia de Aminoácidos , Animales , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Femenino , Genes Reporteros , Gónadas/metabolismo , Inmunohistoquímica , Péptidos y Proteínas de Señalización Intracelular , Masculino , Ratones , Ratones Endogámicos BALB C , Datos de Secuencia Molecular , Proteínas Nucleares/química , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Plásmidos , Embarazo , Regiones Promotoras Genéticas , Proteínas Quinasas/genética , Proteínas Quinasas/metabolismo , Proteínas Serina-Treonina Quinasas , Estructura Terciaria de Proteína , Proteínas Recombinantes de Fusión/metabolismo , Proteínas Represoras/genética , Proteínas Represoras/metabolismo , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Homología de Secuencia de Aminoácido , Espermatocitos/metabolismo , Espermatogonias/metabolismo , Factores de Transcripción/química , Factores de Transcripción/genética , Factores de Transcripción/metabolismoRESUMEN
Pim-1 and Pim-2 are murine proto-oncogenes implicated in lymphomagenesis. The aim of this study was to investigate whether the human Pim-2 (hPim-2) expression is altered in chronic lymphocytic leukemia (B-CLL) and non-Hodgkin's lymphomas (NHL). We analyzed hPim-2 expression in 48 patients with NHL and CLL by quantitative in-situ hybridization, quantitative RT-PCR and FACS analysis. In-situ hybridization revealed a 5.5 +/- 2.2 times higher expression of hPim-2 in NHL over normal lymphocytes (P < 0.001). Similarly, with quantitative RT-PCR, expression in NHL was 1.5 to 2.6 times higher in involved splenic foci compared to nearby uninvolved regions (n = 3). hPim-2 mRNA was increased 3-folds in B-CLL over normal B-cells (P < 0.006). The increased hPim-2 levels correlated with lymphocyte doubling time (DT), in that mRNA levels were two times greater in patients with rapid DT (P < 0.006). Moreover, a significant correlation was found between hPim-2 expression and the Binet staging system of CLL (P < 0.022). The hPIM-2-protein expression was also upregulated in CLL, as assessed by FACS analysis. Therefore, this report provides direct evidence for a linkage of hPim-2 upregulation to NHL and CLL in man. This relationship between hPim-2 and NHL and CLL raises a number of novel mechanistic options for the genesis and/or progression of some types of human lymphomas.