PT - JOURNAL ARTICLE AU - Kiger, Amy A. AU - Jones, D. Leanne AU - Schulz, Cordula AU - Rogers, Madolyn B. AU - Fuller, Margaret T. TI - Stem Cell Self-Renewal Specified by JAK-STAT Activation in Response to a Support Cell Cue AID - 10.1126/science.1066707 DP - 2001 Dec 21 TA - Science PG - 2542--2545 VI - 294 IP - 5551 4099 - http://science.sciencemag.org/content/294/5551/2542.short 4100 - http://science.sciencemag.org/content/294/5551/2542.full SO - Science2001 Dec 21; 294 AB - Stem cells generate many differentiated, short-lived cell types, such as blood, skin, and sperm, throughout adult life. Stem cells maintain a long-term capacity to divide, producing daughter cells that either self-renew or initiate differentiation. Although the surrounding microenvironment or “niche” influences stem cell fate decisions, few signals that emanate from the niche to specify stem cell self-renewal have been identified. Here we demonstrate that the apical hub cells in the Drosophila testis act as a cellular niche that supports stem cell self-renewal. Hub cells express the ligand Unpaired (Upd), which activates the Janus kinase–signal transducer and activator of transcription (JAK-STAT) pathway in adjacent germ cells to specify self-renewal and continual maintenance of the germ line stem cell population.