Comparative genomic and transcriptomic studies of Leishmania major depleted of basic components of telomerase

• Grant number: 24/23269-0
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: April 01, 2025
• End date: March 31, 2027
• Field of knowledge: Biological Sciences - Genetics - Molecular Genetics and Genetics of Microorganisms
• Principal Investigator: Maria Isabel Nogueira Cano
• Grantee: Arthur de Oliveira Passos
• Host Institution: Instituto de Biociências (IBB). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil
• Associated research grant: 18/04375-2 - Studies about the biogenesis and composition of the Leishmania spp. ribonucleoprotein complex and its regulation, AP.TEM

Abstract

Protozoan parasites of the Leishmania genus are the causative agents of leishmaniasis, neglected diseases that affect approximately 350 million people annually and for which there are still no effective treatments or controls. These limitations highlight the need for efforts to develop therapeutic alternatives for controlling these diseases. Telomeres are nucleoprotein structures located at the ends of linear chromosomes, protecting and maintaining the integrity of genetic material. Composed by tandem repeats of the 5'-TTAGGG-3' hexamer sequence, these structures are conserved across a range of eukaryotes, including Leishmania. In human somatic cells, telomeres progressively shorten with each replication cycle, leading to replicative senescence and, ultimately, the cessation of cell division. To counteract this, the telomerase complex, active in certain cell types, elongates and maintains telomeres. Advances in sequencing technologies have revealed that telomeres are more heterogeneous than previously thought, with variant sequences commonly found at chromosomal ends in diverse organisms. These telomeric variant sequences (TVSs) may alter local chromatin composition and protein-telomere interactions. However, the genomes of Leishmania major in public databases still contain gaps in telomeric regions, complicating detailed studies of these structures. This lack of data limits our understanding of telomere biology in Leishmania spp. and precludes comprehensive analyses of these chromosomal regions. Recent findings from our research group show that the absence of telomerase components (TERT and TER) via gene knockout induces telomere shortening and reduces or completely inhibits the parasite's infective capacity, suggesting telomeres as potential therapeutic targets. Using Oxford Nanopore long-read sequencing, this study aims to investigate telomere size and heterogeneity in Leishmania major, comparing wild-type strains with TERT and TER knockouts across different passages. Additionally, we will assess alternative telomere elongation (ALT) mechanisms, as telomerase-depleted parasites still replicate in vitro. To understand the relationship between telomere alterations and loss of infectivity, transcriptomic analyses will be also employed for identifying differentially expressed genes between wild-type and knockout strains.