RESUMEN
Galectins control cell behavior by acting on different signaling pathways. Most of the biological activities ascribed to these molecules rely upon recognition of extracellular glycoconjugates and establishment of multivalente interactions, which trigger adaptive biological responses. However, galectins are also detected within the cell in different compartments, where their regulatory functions still remain poorly understood. A deeper understanding of the entire galectin signalosome and its impact in cell behavior is therefore essential in order to delineate new strategies to specifically manipulate both galectin expression and function. This review summarizes our current knowledge of the signaling pathways activated by galectins, their glycan dependence and the cellular compartment where they become activated and are biologically relevant.
Asunto(s)
Galectinas/metabolismo , Animales , Carcinogénesis/metabolismo , Adhesión Celular/fisiología , Humanos , Transducción de Señal/fisiologíaRESUMEN
We investigated the binding and the translation inhibitory properties of hexadecamers complementary to the mini-exon sequence of the protozoan parasite Leishmania amazonensis. This targeted RNA region folds into a hairpin. Large differences were observed in the antisense properties of the different oligomers although their binding to RNA always requires the disruption of the stem region.
Asunto(s)
Exones , Leishmania/efectos de los fármacos , Conformación de Ácido Nucleico , Oligonucleótidos Antisentido/farmacología , ARN Protozoario/química , Animales , Secuencia de Bases , Leishmania/genéticaRESUMEN
Complementary oligodeoxynucleotides (ODNs) that contain 2-aminoadenine and 2-thiothymine interact weakly with each other but form stable hybrids with unmodified complements. These selectively binding complementary (SBC) agents can invade duplex DNA and hybridize to each strand (Kutyavin, I. V., Rhinehart, R. L., Lukhtanov, E. A., Gorn, V. V., Meyer, R. B., and Gamper, H. B. (1996) Biochemistry 35, 11170-11176). Antisense ODNs with similar properties should be less encumbered by RNA secondary structure. Here we show that SBC ODNs strand invade a hairpin in the mini-exon RNA of Leishmania amazonensis and that the resulting heteroduplexes are substrates for Escherichia coli RNase H. SBC ODNs either with phosphodiester or phosphorothioate backbones form more stable hybrids with RNA than normal base (NB) ODNs. Optimal binding was observed when the entire hairpin sequence was targeted. Translation of L. amazonensis mRNA in a cell-free extract was more efficiently inhibited by SBC ODNs complementary to the mini-exon hairpin than by the corresponding NB ODNs. Nonspecific protein binding in the cell-free extract by phosphorothioate SBC ODNs rendered them ineffective as antisense agents in vitro. SBC phosphorothioate ODNs displayed a modest but significant improvement of leishmanicidal properties compared with NB phosphorothioate ODNs.
Asunto(s)
Exones , Leishmania/genética , Conformación de Ácido Nucleico , Oligonucleótidos Antisentido/metabolismo , Biosíntesis de Proteínas , ARN Mensajero/metabolismo , ARN Protozoario/metabolismo , Animales , Secuencia de Bases , Mapeo Cromosómico , Calor , Datos de Secuencia Molecular , Tionucleótidos/metabolismoRESUMEN
Chemically-modified oligonucleotides are now routinely used to prevent gene expression in cell-free media and in cultured cells. The binding of an antisense sequence to a complementary RNA target may lead to the selective inhibition of the encoded information. This may occur at different levels: splicing; transport of the mature RNA from the nucleus to the cytoplasm; translation. Antisense oligonucleotides constitute an interesting tool to shed some light on gene function. They are also potential new therapeutic agents against pathogenic organisms. This review discusses the rules that guide the design of an antisense oligomer and the choice of a target sequence. Examples of the potential use of antisense oligonucleotides in the fields of virology and parasitology, in particular in relation to trypanosomatids, are described.