Stem Cell Self-Renewal Specified by JAK-STAT Activation in Response to a Support Cell Cue

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Science  21 Dec 2001:
Vol. 294, Issue 5551, pp. 2542-2545
DOI: 10.1126/science.1066707

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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.

  • * These authors contributed equally to this work.

  • Present address: Department of Genetics, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA.

  • To whom correspondence should be addressed at the Department of Developmental Biology, Beckman Center B300, 279 Campus Drive, Stanford University School of Medicine, Stanford, CA 94305–5329, USA. E-mail: fuller{at}

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