<em>trt-1</em> Is the Caenorhabditis elegans Catalytic Subunit of Telomerase

Mutants of trt-1, the Caenorhabditis elegans telomerase reverse transcriptase, reproduce normally for several generations but eventually become sterile as a consequence of telomere erosion and end-to-end chromosome fusions. Telomere erosion and uncapping do not cause an increase in apoptosis in the germlines of trt-1 mutants. Instead, late-generation trt-1 mutants display chromosome segregation defects that are likely to be the direct cause of sterility. trt-1 functions in the same telomere replication pathway as mrt-2, a component of the Rad9/Rad1/Hus1 (9–1–1) proliferating cell nuclear antigen–like sliding clamp. Thus, the 9–1–1 complex may be required for telomerase to act at chromosome ends in C. elegans. Although telomere erosion limits replicative life span in human somatic cells, neither trt-1 nor telomere shortening affects postmitotic aging in C. elegans. These findings illustrate effects of telomere dysfunction in C. elegans mutants lacking the catalytic subunit of telomerase, trt-1.