piwi encodes a nucleoplasmic factor whose activity modulates the number and division rate of germline stem cells

• Published in: Development (Cambridge) Vol. 127; no. 3; pp. 503 - 514
• Main Authors: Cox, D N, Chao, A, Lin, H
• Format: Journal Article
• Language: English
• Published: England The Company of Biologists Limited 01.02.2000
• Subjects: Animals; Animals, Genetically Modified; Argonaute Proteins; Cell Division; Cell Nucleus - physiology; Drosophila; Drosophila - embryology; Drosophila - genetics; Drosophila Proteins; Female; Genes, myc; Insect Proteins - genetics; Insect Proteins - physiology; Male; Open Reading Frames; Ovary - cytology; Ovary - physiology; Ovum - cytology; Ovum - physiology; piwi gene; PIWI protein; Proteins - genetics; Proteins - physiology; Recombinant Fusion Proteins - biosynthesis; RNA-Induced Silencing Complex; Stem Cells - cytology; Stem Cells - physiology
• ISSN: 0950-1991; 1477-9129
• DOI: 10.1242/dev.127.3.503

piwi represents the first class of genes known to be required for stem cell self-renewal in diverse organisms. In the Drosophila ovary, piwi is required in somatic signaling cells to maintain germline stem cells. Here we show that piwi encodes a novel nucleoplasmic protein present in both somatic and germline cells, with the highly conserved C-terminal region essential for its function. Removing PIWI protein from single germline stem cells significantly decreases the rate of their division. This suggests that PIWI has a second role as a cell-autonomous promoter of germline stem cell division. Consistent with its dual function, over-expression of piwi in somatic cells causes an increase both in the number of germline stem cells and the rate of their division. Thus, PIWI is a key regulator of stem cell division - its somatic expression modulates the number of germline stem cells and the rate of their division, while its germline expression also contributes to promoting stem cell division in a cell-autonomous manner.