Several bacterial fermentation products and their synthetic derivatives display antitumour activities and bind tightly to components of the spliceosome, which is the complex molecular machinery involved in the removal of introns from mRNA precursors in eukaryotic cells. The drugs alter gene expression, including alternative splicing, of genes that are important for cancer progression. A flurry of recent reports has revealed that genes encoding splicing factors, including the drug target splicing factor 3B subunit 1 (SF3B1), are among the most highly mutated in various haematological malignancies such as chronic lymphocytic leukaemia and myelodysplastic syndromes. These observations highlight the role of splicing factors in cancer and suggest that an understanding of the molecular effects of drugs targeting these proteins could open new perspectives for studies of the spliceosome and its role in cancer progression, and for the development of novel antitumour therapies.
"Alternative splicing leads to different isoforms of vascular endothelial growth factor, which is responsible for either inhibiting or facilitating the formation of blood vessels, and is known to be a key event in tumor growth and metastasis (Bonnal et al. 2012). mRNA splicing is performed by spliceosome, a macromolecular complex composed of five small nuclear ribonucleoproteins (snRNPs) (U1, U2, U4, U5, and U6) (Lagisetti et al. 2013). "
[Show abstract][Hide abstract] ABSTRACT: Herboxidiene is a polyketide with a diverse range of activities, including herbicidal, anti-cholesterol, and pre-mRNA splicing inhibitory effects. Thus, production of the compound on the industrial scale is in high demand, and various rational metabolic engineering approaches have been employed to enhance the yield. Directing the precursors and cofactors pool toward the production of polyketide compounds provides a rationale for developing a good host for polyketide production. Due to multiple promising biological activities, the production of a number of herboxidiene derivatives has been attempted in recent years in a search for the key to improve its potency and to introduce new activities. Structural diversification through combinatorial biosynthesis was attempted, utilizing the heterologous expression of substrate-flexible glucosyltransferase (GT) and cytochrome P450 in Streptomyces chromofuscus to generate structurally and functionally diverse derivatives of herboxidiene. The successful attempt confirmed that the strain was amenable to heterologous expression of foreign polyketide synthase (PKS) or post-PKS modification genes, providing the foundation for generating novel or hybrid polyketides.
Applied Microbiology and Biotechnology 08/2015; DOI:10.1007/s00253-015-6860-2 · 3.34 Impact Factor
"Recently, mutations in SF3B1 have been linked to various types of cancer (Bonnal et al., 2012), and these mutations are correlated with poor prognosis in patients with chronic lymphocytic leukemia and myelodysplastic disorders (Quesada et al., 2012; Yoshida et al., 2011). Whether the pathogenesis of these mutations is a consequence of reduced levels of functional protein or dominant-negative effects remains unclear. "
"The results shown in Figure 3 reveal a complex picture in which retention of certain introns is clearly increased and retention of other introns is very mild, and there is even one case (the two introns flanking the fibronectin EDI alternative exon) in which the low levels of intron detected under control conditions are reduced upon knockdown of core SFs (notably, this ASE typically displays a distinct pattern of AS upon knockdown of core SFs, Figure 2A). Therefore, rather than a general uniform inhibition of splicing, reduction in the levels of core SFs induces differential effects in different introns, a concept reminiscent of the differential effects observed for antitumor drugs targeting core components like SF3B1 (Bonnal et al., 2012). "
[Show abstract][Hide abstract] ABSTRACT: Pre-mRNA splicing relies on the poorly understood dynamic interplay between >150 protein components of the spliceosome. The steps at which splicing can be regulated remain largely unknown. We systematically analyzed the effect of knocking down the components of the splicing machinery on alternative splicing events relevant for cell proliferation and apoptosis and used this information to reconstruct a network of functional interactions. The network accurately captures known physical and functional associations and identifies new ones, revealing remarkable regulatory potential of core spliceosomal components, related to the order and duration of their recruitment during spliceosome assembly. In contrast with standard models of regulation at early steps of splice site recognition, factors involved in catalytic activation of the spliceosome display regulatory properties. The network also sheds light on the antagonism between hnRNP C and U2AF, and on targets of antitumor drugs, and can be widely used to identify mechanisms of splicing regulation
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