Pax7 is required for the specification of myogenic satellite cells.
The paired box transcription factor Pax7 was isolated by representational difference analysis as a gene specifically expressed in cultured satellite cell-derived myoblasts. In situ hybridization revealed that Pax7 was also expressed in satellite cells residing in adult muscle. Cell culture and electron microscopic analysis revealed a complete absence of satellite cells in Pax7(-/-) skeletal muscle. Surprisingly, fluorescence-activated cell sorting analysis indicated that the proportion of muscle-derived stem cells was unaffected. Importantly, stem cells from Pax7(-/-) muscle displayed almost a 10-fold increase in their ability to form hematopoietic colonies. These results demonstrate that satellite cells and muscle-derived stem cells represent distinct cell populations. Together these studies suggest that induction of Pax7 in muscle-derived stem cells induces satellite cell specification by restricting alternate developmental programs.
Seale
P
P
Department of Biology, McMaster University, Hamilton, Ontario, Canada.
Sabourin
L A
LA
Girgis-Gabardo
A
A
Mansouri
A
A
Gruss
P
P
Rudnicki
M A
MA
D000367:Age Factors; D000818:Animals; D002455:Cell Division / Q000502:physiology; D019070:Cell Lineage / Q000502:physiology; D002462:Cell Membrane / Q000648:ultrastructure; D002467:Cell Nucleus / Q000648:ultrastructure; D002478:Cells, Cultured; D005434:Flow Cytometry; D018507:Gene Expression Regulation, Developmental; D006412:Hematopoietic Stem Cells / Q000737:chemistry / Q000166:cytology*; D018398:Homeodomain Proteins / Q000032:analysis / Q000235:genetics*; D017403:In Situ Hybridization; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D008854:Microscopy, Electron; D018485:Muscle Fibers, Skeletal / Q000737:chemistry / Q000166:cytology*; D018482:Muscle, Skeletal / Q000002:abnormalities* / Q000737:chemistry / Q000648:ultrastructure; D051763:PAX7 Transcription Factor; D012333:RNA, Messenger / Q000032:analysis
D018398:Homeodomain Proteins; D051763:PAX7 Transcription Factor; C497322:Pax7 protein, mouse; D012333:RNA, Messenger