Telomeric Repeat-Binding Factor Homologs in Entamoeba histolytica: New Clues for Telomeric Research

Abstract

Telomeric Repeat Binding Factors (TRFs) are architectural nuclear proteins with critical roles in telomere-length regulation, chromosome end protection and, fusion prevention, DNA damage detection, and senescence regulation. Entamoeba histolytica, the parasite responsible of human amoebiasis, harbors three homologs of human TRFs, based on sequence similarities to their Myb DNA binding domain. These proteins were dubbed EhTRF-like I, II and III. In this work, we revealed that EhTRF-like I and II share similarity with human TRF1, while EhTRF-like III shares similarity with human TRF2 by in silico approach. The analysis of ehtrf-like genes showed they are expressed differentially under basal culture conditions. We also studied the cellular localization of EhTRF-like I and III proteins using subcellular fractionation and western blot assays. EhTRF-like I and III proteins were enriched in the nuclear fraction, but they were also present in the cytoplasm. Indirect immunofluorescence showed that these proteins were located at the nuclear periphery co-localizing with Lamin B1 and trimethylated H4K20, which is a characteristic mark of heterochromatic regions and telomeres. We found by transmission electron microscopy that EhTRF-like III was located in regions of more condensed chromatin. Finally, EMSA assays showed that EhTRF-like III forms specific DNA-protein complexes with telomeric related sequences. Our data suggested that EhTRF-like proteins play a role in the maintenance of the chromosome ends in this parasite.

Selective pericentromeric heterochromatin dismantling caused by TP53 activation during senescence

“…This also indicates that TRF2 controls the association of LMNB1 to PCH. This might result from a direct TRF2-LMNB1 interaction that is currently under investigation (Mendez-Bermudez et al, unpublished) and previously suggested for the TRF2 ortholog of the parasite Entamoeba histolytica 34 .…”

Genome-Wide Classification of Myb Domain-Containing Protein Families in Entamoeba invadens

“…Lastly, eitrf-like I and II are expressed in specific stages (Figure 5B) in which replication occurs, as nuclear division is necessary for encystment; therefore, these proteins could be required for telomeric protection. TRF-like proteins have been identified and characterized in T. brucei, T. cruzi, L. major, and E. histolytica, where their role as telomere DNA-binding proteins has been reported to provide a possible function in telomere-end protection [24,25,68].…”