Inhibitor of Differentiation 4 (ID4) represses mammary myoepithelial differentiation via inhibition of HEB

Holly Holliday; Daniel Roden; Simon Junankar; Sunny Z Wu; Laura A Baker; Christoph Krisp; Chia-Ling Chan; Andrea McFarland; Joanna N Skhinas; Thomas R Cox; Bhupinder Pal; Nicholas D Huntington; Christopher J Ormandy; Jason S Carroll; Jane Visvader; Mark P Molloy; Alexander Swarbrick

doi:10.1016/j.isci.2021.102072

Inhibitor of Differentiation 4 (ID4) represses mammary myoepithelial differentiation via inhibition of HEB

iScience. 2021 Jan 20;24(2):102072. doi: 10.1016/j.isci.2021.102072. eCollection 2021 Feb 19.

Authors

Holly Holliday^{1

2}, Daniel Roden^{1

2}, Simon Junankar^{1

2}, Sunny Z Wu^{1

2}, Laura A Baker^{1

2}, Christoph Krisp^{3

4}, Chia-Ling Chan¹, Andrea McFarland¹, Joanna N Skhinas¹, Thomas R Cox^{1

2}, Bhupinder Pal^{5

6}, Nicholas D Huntington⁷, Christopher J Ormandy^{1

2}, Jason S Carroll⁸, Jane Visvader^{5

9}, Mark P Molloy³, Alexander Swarbrick^{1

2}

Affiliations

¹ The Kinghorn Cancer Centre, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia.
² St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW 2010, Australia.
³ Australian Proteome Analysis Facility, Macquarie University, Sydney, NSW 2109, Australia.
⁴ Institute of Clinical Chemistry and Laboratory Medicine, Mass Spectrometric Proteomics, University Medical Center Hamburg-Eppendorf, Hamburg 20251, Germany.
⁵ ACRF Cancer Biology and Stem Cells Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia.
⁶ Olivia Newton-John Cancer Research Institute and School of Cancer Medicine, La Trobe University, Heidelberg, VIC 3084, Australia.
⁷ Biomedicine Discovery Institute, Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3168, Australia.
⁸ Cancer Research UK Cambridge Institute, University of Cambridge, Robinson Way, Cambridge CB2 0RE, UK.
⁹ Department of Medical Biology, The University of Melbourne, Parkville, VIC 3010, Australia.

Abstract

Inhibitor of differentiation (ID) proteins dimerize with basic HLH (bHLH) transcription factors, repressing transcription of lineage-specification genes across diverse cellular lineages. ID4 is a key regulator of mammary stem cells; however, the mechanism by which it achieves this is unclear. Here, we show that ID4 has a cell autonomous role in preventing myoepithelial differentiation of basal cells in mammary organoids and in vivo. ID4 positively regulates proliferative genes and negatively regulates genes involved in myoepithelial function. Mass spectrometry reveals that ID4 interacts with the bHLH protein HEB, which binds to E-box motifs in regulatory elements of basal developmental genes involved in extracellular matrix and the contractile cytoskeleton. We conclude that high ID4 expression in mammary basal stem cells antagonizes HEB transcriptional activity, preventing myoepithelial differentiation and allowing for appropriate tissue morphogenesis. Downregulation of ID4 during pregnancy modulates gene regulated by HEB, promoting specialization of basal cells into myoepithelial cells.

Keywords: cell biology; developmental biology; molecular biology; stem cells research.

Grants and funding

20411/CRUK_/Cancer Research UK/United Kingdom