Reciprocal intraepithelial interactions between TP63 and hedgehog signaling regulate quiescence and activation of progenitor elaboration by mammary stem cells.
TP63 is required for preservation of epithelial regenerative stasis and regulates the activity of diverse genetic pathways; however, specific effector pathways are poorly understood. Data presented here indicate that reciprocal regulatory interactions between hedgehog signaling and TP63 mediate stage-specific effects on proliferation and clonigenicity of separable enriched mammary stem and progenitor fractions. Analysis of DeltaN-p63 and TA-p63 indicates segregated expression in mammary stem and progenitor fractions, respectively, demonstrating that differential TP63 promoter selection occurs during elaboration of mammary progenitors by mammary stem cells. This segregation underlies mammary progenitor-specific expression of Indian Hedgehog, identifying it as a binary transcriptional target of TP63. Hedgehog activation in vivo enhances elaboration of mammary progenitors and decreases label retention within mammary stem cell-enriched fractions, suggesting that hedgehog exerts a mitogenic effect on mammary stem cells. Hedgehog signaling promotes differential TP63 promoter usage via disruption of Gli3 or Gli3(R) accumulation, and shRNA-mediated disruption of Gli3 expression was sufficient to alter TP63 promoter usage and enhance clonigenicity of mammary stem cells. Finally, hedgehog signaling is enhanced during pregnancy, where it contributes to expansion of the mammary progenitor compartment. These studies support a model in which hedgehog activates elaboration and differentiation of mammary progenitors via differential TP63 promoter selection and forfeiture of self-renewing capacity.
Li
Na
N
Department of Pharmacology and Toxicology, Dartmouth Medical School, 7650 Remsen, Hanover, New Hampshire 03755, USA.
Singh
Samer
S
Cherukuri
Pratima
P
Li
Hua
H
Yuan
Ziqiang
Z
Ellisen
Leif W
LW
Wang
Baolin
B
Robbins
David
D
DiRenzo
James
J
D000818:Animals; D002460:Cell Line; D004847:Epithelial Cells / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation; D053823:Hedgehog Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051741:Kruppel-Like Transcription Factors / Q000378:metabolism; D008321:Mammary Glands, Animal / Q000166:cytology* / Q000378:metabolism; D051379:Mice; D008954:Models, Biological; D009419:Nerve Tissue Proteins / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D011247:Pregnancy; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D000074290:Zinc Finger Protein Gli3
C465571:Gli3 protein, mouse; D053823:Hedgehog Proteins; D051741:Kruppel-Like Transcription Factors; D009419:Nerve Tissue Proteins; D010750:Phosphoproteins; D020033:Protein Isoforms; D015534:Trans-Activators; C486419:Trp63 protein, mouse; D000074290:Zinc Finger Protein Gli3; C514061:ihh protein, mouse