Dedifferentiation of muscle cells during Trichinella spiralis infection

The first stage larvae (L1) of the obligate parasitic nematode Trichinella spiralis invades host skeletal muscle cells and reside intracellularly. The host cell is dedifferentiated, losing its muscular specialisation, and re-entering the cell cycle transiently. Over a period of around 20 days post-invasion the host cell is converted into a “nurse cell” within which the L1 can remain for decades unimpeded. Coinciding with the establishment and maturation of the nurse cell is the development of the L1. The L1 develops a mature secretory organ, the stichosome, and a more complex cuticle and grows exponentially for weeks. The link between the development of a dedicated secretory organ, alongside the dedifferentiation of the host muscle cell is an area currently under investigation. The excretory/secretory products (ESPs) produced by the worm directly into the host cell are implicated as effectors of host cell dedifferentiation, among other nurse cell constructing processes. The identification of ESPs able to manipulated the differentiated state of muscle cells warrants investigation in developing treatments for muscle wasting diseases. The work undertaken in this thesis aims to enhance the current understanding of the process of dedifferentiation observed during infection and identify the parasite factors involved. ESPs produced by muscle released larvae are identified by proteomics and functionally annotated. Using this set of ESPs, a novel motif is determined that is enriched upstream of the Transcription Start Site (TSS) of ESP genes relative to non-ESP genes. Characterisation is undertaken of selected ESPs that have proposed involvement in the manipulation of cell cycle and differentiative processes. Finally, the transcriptomic events underpinning the dedifferentiation and redifferentiation of the host cells in early muscle infection are uncovered through a novel synchronous dual-species transcriptomic approach. Features associated with the ESPs, are used to predict ESPs from L1 genes differentially expressed during the early stages of infection. My work combines the independent analyses of L1 secretome data and synchronised dual-species transcriptomic data. This approach identifies a novel ESP associated motif, previously unreported ESPs collected from culture, stage specific parasite transcripts and an improved synchronous infection collection method to identify host processes and worm transcripts at high resolution. Ultimately, this thesis advances our scientific understanding of the genes from both the parasite and the host that contribute to the dedifferentiation of muscle cells during T. spiralis infection.

Name dc:type.qualificationname

Doctor of Philosophy (PhD)

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

University of Cambridge

Year dc:date.issued

2022

Author dc:creator

• Nash, Bradley

Advisors dc:contributor.advisor

• Artavanis-Tsakonas, Katerina
• Protasio, Anna

• Trichinella spiralis
• Secretome
• Transcriptome
• Dual-Species

Licence

• http://purl.org/NET/rdflicense/allrightsreserved

Language dc:language

eng

DOI dc:identifier.doi

https://doi.org/10.17863/CAM.87161

OAI identifier oai:identifier

oai:www.repository.cam.ac.uk:1810/339742