TLS/FUS (translocated in liposarcoma/fused in sarcoma) regulates target gene transcription via single-stranded DNA response elements

Abstract

TLS/FUS (TLS) is a multifunctional protein implicated in a wide range of cellular processes, including transcription and mRNA processing, as well as in both cancer and neurological disease. However, little is currently known about TLS target genes and how they are recognized. Here, we used ChIP and promoter microarrays to identify genes potentially regulated by TLS. Among these genes, we detected a number that correlate with previously known functions of TLS, and confirmed TLS occupancy at several of them by ChIP. We also detected changes in mRNA levels of these target genes in cells where TLS levels were altered, indicative of both activation and repression. Next, we used data from the microarray and computational methods to determine whether specific sequences were enriched in DNA fragments bound by TLS. This analysis suggested the existence of TLS response elements, and we show that purified TLS indeed binds these sequences with specificity in vitro. Remarkably, however, TLS binds only single-strand versions of the sequences. Taken together, our results indicate that TLS regulates expression of specific target genes, likely via recognition of specific single-stranded DNA sequences located within their promoter regions.

ALS mutations in TLS/FUS disrupt target gene expression

“…1b). Again, as observed previously (Tan et al 2012), wild-type FUS produced only a modest increase in both isoforms (Fig. 2D, cf.…”

“…wild-type FUS signal in lanes 3 and 7). On the other hand, the recessive FUS Q behaved indistinguishably from wild-type FUS, which increased total MECP2 mRNA levels only slightly (see also Tan et al 2012) but had no differential effect on the e1 and e2 isoforms (Fig. 2C [cf.…”

“…As mentioned above, we previously identified a number of putative FUS targets, one of which was MECP2 (Tan et al 2012). Given that MECP2 has other features of FUS-regulated genes-e.g., potential FUS-RNA interaction motifs and an exceptionally long intron (see Fig.…”

“…An important question is whether ALS mutant FUS proteins can lead to altered splicing and/or expression of specific genes. We previously used a chromatin immunoprecipitation (ChIP) promoter microarray approach to identify putative FUS target genes and showed that several of them could indeed be regulated by FUS (Tan et al 2012). One of these genes was MECP2, which is implicated in another neurological disease, Rett syndrome.…”

An ALS-associated mutation in the FUS 3′-UTR disrupts a microRNA–FUS regulatory circuitry

“…The mild effect observed likely reflects the fact that the in vitro system does not allow the proper reconstitution of the process owing to template structural problems or the absence of additional factors acting in vivo. Also, owing to the described role of FUS in transcription 22 and in consideration of the observed upregulation of the pri-miRNA species, we cannot rule out the possibility of a more complex effect at the level of transcription. Moreover, as indicated above, part of the increase in miR-141/200a biogenesis could be a result of the downregulation of Zeb1.…”