title: Myb controls intestinal stem cell genes and self-renewal.
abstract: Rapid advances have been made in the understanding of how the highly proliferative gastrointestinal tract epithelium is regulated under homeostasis and disease. The identification of putative intestinal stem cell (ISC) genes and the ability to culture ISC capable of generating all four lineages plus the architecture of small intestinal (SI) crypts has been transformative. Here, we show that transcription factor Myb governs ISC gene expression, particularly Lgr5. Lgr5 is associated with cells that have the capacity to generate all cell lineages in SI organoid cultures and colorectal cancer cells, which overexpress Myb. Furthermore, Wnt signaling and Myb cooperate in maximal Lgr5 promoter activation while hypomorphic Myb (plt4/plt4) mice have decreased Lgr5 expression. After ionizing radiation (IR), ISC genes are elevated; but in plt4/plt4 mice, this response is substantially subdued. ISC genes bmi-1 and olfm4 are expressed at subnormal levels in plt4/plt4 mice, and bmi-1 is induced with IR to half the level in mutant mice. dcamkl-1 and olfm4 failed to recover after IR in both wild-type (wt) and mutant mice. Although not considered as an ISC gene, cyclinE1 is nevertheless used to assist cells in the emergence from a quiescent state (an expectation of ISC following IR) and is overexpressed after IR in wt mice but does not change from a very low base in plt4/plt4 mice. Self-renewal assays using organoid cultures and inducible Myb knockout studies further highlighted the dependence of ISC on Myb consistent with role in other stem cell-containing tissues.
authors: Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.
authors: Dane
authors: D
authors: Cheasley
authors: Lloyd
authors: L
authors: Pereira
authors: Sally
authors: S
authors: Lightowler
authors: Elizabeth
authors: E
authors: Vincan
authors: Jordane
authors: J
authors: Malaterre
authors: Robert G
authors: RG
authors: Ramsay
mesh_terms: D000818:Animals; D018929:Cell Culture Techniques; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D015179:Colorectal Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D019927:Cyclin E / Q000235:genetics / Q000378:metabolism; D005720:Gamma Rays; D015972:Gene Expression Regulation, Neoplastic; D020570:Genes, myb; D006801:Humans; D007583:Jejunum / Q000166:cytology* / Q000378:metabolism / Q000528:radiation effects; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D041681:NIH 3T3 Cells; D015513:Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D020598:Proto-Oncogene Proteins c-myb / Q000235:genetics / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*; D015533:Transcriptional Activation; D060449:Wnt Signaling Pathway
chemical_list: D019927:Cyclin E; C116884:LGR5 protein, human; C493597:Lgr5 protein, mouse; D015513:Oncogene Proteins; D020598:Proto-Oncogene Proteins c-myb; D043562:Receptors, G-Protein-Coupled; C568314:cyclin E1, mouse