RNA-binding proteins involved in the secretion of extracellular miRNA by Trichinella spiralis
File(s)
Author(s)
Brown, Alice
Type
Thesis
Abstract
Micro RNAs (miRNAs) play important roles in post-transcriptional regulation of various biological processes. They have been found in a range of extracellular spaces, which has sparked interest in their potential role in cell-to-cell communication. Parasitic nematodes secrete a range of mediators, including small RNAs (sRNAs), to manipulate their host environment, and it is possible that extracellular miRNAs are also involved in parasite-to-host communication. However, the mechanism of secretion and selection of specific miRNAs for export is unclear. The intramuscular stage of the parasitic nematode Trichinella spiralis secretes unencapsulated miRNA, which contrasts with the adult stage, as well as other systems, in which miRNAs are exported in vesicles. This raises questions over whether the unencapsulated miRNAs are secreted via direct release or in complex with a chaperone protein, which could offer protection in the absence of a membrane. This work explores the secretome of T. spiralis muscle-stage larvae (MSL) to identify candidate RNA-binding proteins which may be involved in miRNA secretion. Using bioinformatic and experimental characterisation, I have discovered two proteins secreted by T. spiralis MSL which interact with T. spiralis miRNA in the extracellular space. One of these proteins, I have named TsPUF, is an uncharacterised protein unique to nematodes that appears to bind RNA non-selectively via a non-canonical RNA-binding domain. The other protein is a homologue of the mammalian RNA-binding protein KSRP, and binds to miRNA in a selective and sequence-specific manner. The results suggest a possible mechanism for miRNA secretion by T. spiralis involving TsPUF and TsKSRP. Further investigation is needed to determine the role of these proteins in miRNA binding. The findings give insight into the mechanism by which parasite miRNAs manipulate the host environment as well as broad insights into the secretion of extracellular sRNAs in various physiological and pathological processes.
Version
Open Access
Date Issued
2023-07
Date Awarded
2024-01
Copyright Statement
Creative Commons Attribution NonCommercial Licence
License URL
Advisor
Sarkies, Peter
Selkirk, Murray
Sponsor
Medical Research Council (Great Britain)
Publisher Department
Institute of Clinical Sciences
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)