Studies on the function of the leishmania major telomerase tert component in telomeres maintenance, cell proliferation, and infectivity
Over 98 countries and territories have reported cases of leishmaniasis, a disease affecting nearly a million individuals annually but with ineffective remedies. Our goal was to study the function of the telomerase reverse transcriptase (TERT) in Leishmania major (LmTERT) and leverage this knowledge...
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| Format: | doctoral thesis |
| Status: | Published version |
| Publication Date: | 2024 |
| Country: | Brasil |
| Institution: | Universidade Estadual Paulista (UNESP) |
| Repository: | Repositório Institucional da UNESP |
| Language: | English |
| OAI Identifier: | oai:repositorio.unesp.br:11449/253152 |
| Online Access: | https://hdl.handle.net/11449/253152 |
| Access Level: | Open access |
| Keyword: | TERT gene function Leishmaniasis telomere shortening CRISPR-Cas9 growth, and ultrastructural changes compromised cell proliferation DNA damage loss of infectivity BIBR1532 inhibition Autophagy Cell cycle arrest |
| Summary: | Over 98 countries and territories have reported cases of leishmaniasis, a disease affecting nearly a million individuals annually but with ineffective remedies. Our goal was to study the function of the telomerase reverse transcriptase (TERT) in Leishmania major (LmTERT) and leverage this knowledge in developing new drugs. The TERT component contains the catalytic core of telomerase, the enzyme responsible for elongating telomeres and maintaining genome stability. A loss of function study using CRISPR-Cas9 and inhibition of the telomerase in L. major was conducted. Probe-specific Southern blot, PCR, and primer walk Sanger sequencing confirmed the efficient deletion of the TERT gene in L. major. The knockout of the TERT gene resulted in parasite growth defects, DNA fragmentation, cell cycle arrest, and problematic replication measured by flow cytometry. Progressive telomere shortening, the hallmark of TERT absence, was observed by Southern TRF and Flow-FISH assessments. We also assessed the subcellular structures of the LmTERT knockout cells against a wild type using scanning and electron microscopy and found unusual modifications in the cytoplasm, and an abundance of autophagosomes, suggesting a pro-survival autophagic mechanism. Changes in the metacyclic domain proteins were seen equally in the knockout lines. An altruistic mechanism used by the parasites was abolished. The cumulative results suggesting a compromise on parasite infective potential was confirmed by in vivo BALB/c mice infection study and in vitro bone-marrow derived macrophage infection. Significant lesion development was observed in the mice infected with control parasites against those infected with the knockout lineage. A consistently higher infectivity index was observed for control versus knockout lineages at 48 h post-inoculation. Consistent with the growth challenges and telomere shortening, preliminary tests of the inhibition of the telomerase using BIBR1532, a non-nucleoside small molecule, resulted in shorter telomeres and poor parasite growth. These results together suggest the usefulness of LmTERT to the parasite, putting the protein in a space to be explored for drug development against leishmaniasis. |
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