The Telomerase RNA Stays in the Nucleus in Aspergillus nidulans

Abstract

Telomeres are protein‐nucleotide sequences at the ends of chromosomes that serve to prevent the loss of genetic information during cell replication. A telomerase ribonucleoprotein complex includes telomerase reverse transcriptase (TERT) and an RNA template (TER) and is responsible for adding telomeric DNA. Our lab has been studying the biogenesis of telomerase in the fungus Aspergillus nidulans. Previous research on TER indicated secondary structural similarities to both Saccharomyces cerevisiae and mammalian cells. However, it was previously unknown whether TER migrates into the cytoplasm during the assembly of telomerase, as in S. cerevisiae, or remains in the nucleus, as in mammalian cells. We now have employed a molecular tool, the unique multi‐nucleate state of A. nidulans termed heterokaryon, to deduce whether the RNA products for TER and TERT leave the nucleus. We knocked out the genes for TER and TERT, analyzed the results of the heterokaryon test, determined whether assembly occurs in the nucleus or cytoplasm, and verified those results with DAPI staining. Our results suggest assembly in the nucleus, a scenario that is similar to humans, but not to yeast. These results further suggest the strength of A. nidulans as a model organism in studying the localization of telomerase components.