A mortalin-like gene is crucial for planarian stem cell viability.
In adult organisms, stem cells are crucial to homeostasis and regeneration of damaged tissues. In planarians, adult stem cells (neoblasts) are endowed with an extraordinary replicative potential that guarantees unlimited replacement of all differentiated cell types and extraordinary regenerative ability. The molecular mechanisms by which neoblasts combine long-term stability and constant proliferative activity, overcoming the impact of time, remain by far unknown. Here we investigate the role of Djmot, a planarian orthologue that encodes a peculiar member of the HSP70 family, named Mortalin, on the dynamics of stem cells of Dugesia japonica. Planarian stem cells and progenitors constitutively express Djmot. Transient Djmot expression in differentiated tissues is only observed after X-ray irradiation. DjmotRNA interference causes inability to regenerate and death of the animals, as a result of permanent growth arrest of stem cells. These results provide the first evidence that an hsp-related gene is essential for neoblast viability and suggest the possibility that high levels of Djmot serve to keep a p53-like protein signaling under control, thus allowing neoblasts to escape cell death programs. Further studies are needed to unravel the molecular pathways involved in these processes.
Conte
Maria
M
Dipartimento di Biologia, Università di Pisa, I-56017 Ghezzano, Italy.
Deri
Paolo
P
Isolani
Maria Emilia
ME
Mannini
Linda
L
Batistoni
Renata
R
D000595:Amino Acid Sequence; D000818:Animals; D016923:Cell Death; D002454:Cell Differentiation; D002470:Cell Survival; D004625:Embryo, Nonmammalian / Q000378:metabolism; D017238:Genes, Helminth; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism; D015801:Helminth Proteins / Q000235:genetics* / Q000378:metabolism; D007150:Immunohistochemistry; D008969:Molecular Sequence Data; D010932:Planarians / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism
D018840:HSP70 Heat-Shock Proteins; D015801:Helminth Proteins; C080352:mortalin