The La antigen associates with the human telomerase ribonucleoprotein and influences telomere length in vivo

La is an important component of ribonucleoprotein complexes and telomerase Is a ribonucleoprotein that compensates for the shortening of the ends of l inear DNA by adding telomeric repeats onto the ends of chromosomes by using an integral RNA as the template. We have identified a direct and specific interaction between La and the RNA component of human telomerase. Antibodie s specific to La precipitate the human telomerase ribonucleoprotein complex derived from tumor cells, telomerase immortalized normal cells, and in vit ro transformed cells. Overexpression of La in both experimentally immortali zed human cells and prostate cancer cells results in gradual telomere short ening. Our results demonstrate that La can associate with telomerase and it s expression level can influence telomere homeostasis in vivo.