Armes, H. | Search bioRxiv

bioRxiv2022

A dual role for the RNA helicase DHX34 in NMDand pre-mRNA splicing and its function inhematopoietic differentiation

The DExD/H-box RNA helicase DHX34 is a Nonsense-mediated decay (NMD) factor that together with core NMD factors co-regulates NMD targets in nematodes and in vertebrates. Here, we show that DHX34 is also associated with the human spliceosomal catalytic C complex. Mapping of DHX34 endogenous binding sites using Cross-Linking Immunoprecipitation (CLIP) revealed that DHX34 is preferentially associated with pre-mRNAs and locates at exon-intron boundaries. Accordingly, we observed that DHX34 regulates a large number of alternative splicing (AS) events in mammalian cells in culture, establishing a dual role for DHX34 in both NMD and pre-mRNA splicing. We previously showed that germline DHX34 mutations associated to familial Myelodysplasia (MDS)/Acute Myeloid Leukemia (AML) predisposition abrogate its activity in NMD. Interestingly, we observe now that DHX34 regulates the splicing of pre-mRNAs that have been linked to AML/MDS predisposition. This is consistent with silencing experiments in hematopoietic stem/progenitor cells (HSPCs) showing that loss of DHX34 results in differentiation blockade of both erythroid and myeloid lineages, which is a hallmark of AML development. Altogether, these data unveil new cellular functions of DHX34 and suggests that alterations in the levels and/or activity of DHX34 could contribute to human disease.

molecular biology↗

bioRxiv2020

Expression and function of murine WFDC2 in the respiratory tract.

WFDC2/HE4 encodes a poorly characterised secretory protein that shares structural similarity with multifunctional host defence proteins through possession of two conserved Whey Acidic Protein/four disulphide-core (WFDC) domains. WFDC2 is expressed in multiple epithelia and although its function remains unresolved, it is also overexpressed in a number of human cancers and has an established role as a cancer marker. Currently, little is known about the distribution of WFDC2 in the mouse and thus we have systematically analysed the mouse wfdc2 gene, its expression and distribution. We have used recombinant WFDC2 for functional studies. Wfdc2 is the most highly expressed family member in the lung and is enriched in the nasopharynx. Wfdc2 is the most highly expressed family member in differentiated epithelial cells isolated from the trachea, nasal passages and middle ear. Wfdc2 consists of 5 exons with exon 3 encoding an unstructured linker region that separates the two WFDC domains. This genomic organisation appears to be restricted to the Muridae and Cricetidae families of rodents. Similar to the situation in man, mouse wfdc2 can be alternatively spliced to yield a number of distinct transcripts that have the potential to generate a repertoire of distinct protein isoforms. We used immunohistochemistry to localise the proteins to tissues of the respiratory tract and head and neck regions. Although the protein was limited to epithelial cells of the respiratory tract and nasal and oral cavities, it was expressed in different cells in different regions suggesting expression is governed by a unique regulatory mechanism. Recombinant WFDC2 did not possess antiproteinase activity against trypsin or elastase and had no clear antimicrobial activity.

genomics↗