XXXX cells lacking coilin and Cajal bodies are proficient in telomerase assembly, trafficking and telomere maintenance.

@entity1 @entity35762 @entity7066
The RNA component of @entity1 telomerase ( @entity7066 ) localizes to Cajal bodies, and it has been proposed that Cajal bodies play a role in the assembly of telomerase holoenzyme and telomerase trafficking. Here, the role of Cajal bodies was examined in @entity1 cells deficient of coilin (i.e. coilin-knockout (KO) cells), in which no Cajal bodies are detected. In coilin-KO cells, a normal level of telomerase activity is detected and interactions between core factors of holoenzyme are preserved, indicating that telomerase assembly occurs in the absence of Cajal bodies. Moreover, dispersed @entity7066 aggregates and forms foci specifically during S and G2 phase in coilin-KO cells. Colocalization of these @entity7066 foci with telomeres implies proper telomerase trafficking, independent of Cajal bodies. Therefore, telomerase adds similar numbers of TTAGGG repeats to telomeres in coilin-KO and controls cells. Overexpression of @entity35762 -OB-fold blocks cell cycle-dependent formation of @entity7066 foci and inhibits telomere extension. These findings suggest that telomerase assembly, trafficking and extension occur with normal efficiency in Cajal bodies deficient @entity1 cells. Thus, Cajal bodies, as such, are not essential in these processes, although it remains possible that non-coilin components of Cajal bodies and/or telomere binding proteins (e.g. @entity35762 ) do play roles in telomerase biogenesis and telomere homeostasis.
