Telomerase activity and differential expression of telomerase genes and c‐myc in chicken cells in vitro

This study examined telomerase activity and gene expression profiles for three genes in Gallus gallus domesticus: telomerase reverse transcriptase (chTERT), telomerase RNA (chTR), and c‐myc. Expression of these genes was studied in chicken embryonic stem (chES) cells, chicken embryo fibroblasts (CEFs), and DT40 cells using quantitative real‐time polymerase chain reaction. Our results establish that, relative to transcription levels in telomerase‐negative CEFs, chTERT and chTR are up‐regulated in telomerase‐positive chES cells. Transcription levels of chTERT, chTR, and c‐myc are dramatically up‐regulated in telomerase‐positive DT40 cells, relative to CEFs and chES cells. These results are consistent with a model in which telomerase activity is up‐regulated in proliferating embryonic stem cells requiring stable telomeres to endure multiple rounds of cell division; down‐regulated in differentiated, lifespan‐limited cells; and dramatically up‐regulated in immortalized, transformed cells for which uncontrolled proliferation is correlated with c‐myc dysregulation and telomerase activity. Developmental Dynamics 231:14–21, 2004. © 2004 Wiley‐Liss, Inc.