The TLS/FUS gene is involved in a recurrent chromosomal translocation in human myxoid liposarcomas. We previously reported that TLS is a potential splicing regulator able to modulate the 5-splice site selection in an E1A pre-mRNA. Using an in vitro selection procedure, we investigated whether TLS exhibits a specificity with regard to RNA recognition. The RNAs selected by TLS share a common GGUG motif. Mutation of a G or U residue within this motif abolishes the interaction of TLS with the selected RNAs. We showed that TLS can bind GGUG-containing RNAs with a 250 nM affinity. By UV cross-linking/competition and immunoprecipitation experiments, we demonstrated that TLS recognizes a GGUG-containing RNA in nuclear extracts. Each one of the RNA binding domains (the three RGG boxes and the RNA recognition motif) contributes to the specificity of the TLS⅐RNA interaction, whereas only RRM and RGG2-3 participate to the E1A alternative splicing in vivo. The specificity of the TLS⅐RNA interaction was also observed using as natural pre-mRNA, the G-rich IVSB7 intron of the ␤-tropomyosin pre-mRNA. Moreover, we determined that RNA binding specificities of TLS and high nuclear ribonucleoprotein A1 were different. Hence, our results help define the role of the specific interaction of TLS with RNA during the splicing process of a pre-mRNA. TLS (Translocated in LipoSarcoma)1 or FUS has been first characterized as a rearranged gene in chromosomal translocations specific of human myxoid liposarcoma (1, 2). The resulting fusion protein contains the N-terminal part of TLS fused to a transcription factor of the CAAT/enhancer-binding protein family of proteins: CHOP. In an acute myeloid leukemia, TLS is also involved in a chromosomal breakpoint that juxtaposes the same N-terminal region of TLS to a transcription factor of the ETS proteins family: ERG-1 (3, 4). TLS is highly similar to EWS, a gene implicated in chromosomal translocations that are specific of the tumors of the Ewing family (5, 6). In most of these sarcoma, the N-terminal region of EWS is fused to the DNA binding domain of either ERG-1 or FLI-1, which are two closely related ETS proteins.Both TLS and EWS have in common a similar structural organization. Their C terminus part contains multiple domains that are involved in RNA⅐protein interactions: an RNA recognition motif (RRM) flanked by two regions rich in Arg-Gly-Gly repeats (RGG domains) and a C 2 C 2 zinc finger. In their N terminus domain, they contain a glutamine-, serine-, and tyrosine-rich region that functions as a transcriptional activation domain when fused to a heterologous DNA binding domain (7-9). In oncogenic chimera, the adjunction of this N-terminal region of TLS or EWS to the transcriptional regulators CHOP, FLI-1, or ERG-1 generates proteins with transcriptional activities that differ from those of the wild-type counterpart (8,10). From these data it has been proposed that the oncogenic fusion proteins disturb the expression of genes that are regulated by CHOP, FLI-1, or ERG-1. However, no cellular targe...

Cancer cells display alterations in many cellular processes. One core hallmark of cancer is the Warburg effect which is a glycolytic reprogramming that allows cells to survive and proliferate. Although the contributions of environmental contaminants to cancer development are widely accepted, the underlying mechanisms have to be clarified. Benzo[a]pyrene (B[a]P), the prototype of polycyclic aromatic hydrocarbons, exhibits genotoxic and carcinogenic effects, and it is a human carcinogen according to the International Agency for Research on Cancer. In addition to triggering apoptotic signals, B[a]P may induce survival signals, both of which are likely to be involved in cancer promotion. We previously suggested that B[a]P-induced mitochondrial dysfunctions, especially membrane hyperpolarization, might trigger cell survival signaling in rat hepatic epithelial F258 cells. Here, we further characterized these dysfunctions by focusing on energy metabolism. We found that B[a]P promoted a metabolic reprogramming. Cell respiration decreased and lactate production increased. These changes were associated with alterations in the tricarboxylic acid cycle which likely involve a dysfunction of the mitochondrial complex II. The glycolytic shift relied on activation of the Na+/H+ exchanger 1 (NHE1) and appeared to be a key feature in B[a]P-induced cell survival related to changes in cell phenotype (epithelial-to-mesenchymal transition and cell migration).