| First Author | Bhat R | Year | 2016 |
| Journal | Proc Natl Acad Sci U S A | Volume | 113 |
| Issue | 33 | Pages | E4820-7 |
| PubMed ID | 27496330 | Mgi Jnum | J:235612 |
| Mgi Id | MGI:5796892 | Doi | 10.1073/pnas.1609135113 |
| Citation | Bhat R, et al. (2016) Nuclear repartitioning of galectin-1 by an extracellular glycan switch regulates mammary morphogenesis. Proc Natl Acad Sci U S A 113(33):E4820-7 |
| abstractText | Branching morphogenesis in the mammary gland is achieved by the migration of epithelial cells through a microenvironment consisting of stromal cells and extracellular matrix (ECM). Here we show that galectin-1 (Gal-1), an endogenous lectin that recognizes glycans bearing N-acetyllactosamine (LacNAc) epitopes, induces branching migration of mammary epithelia in vivo, ex vivo, and in 3D organotypic cultures. Surprisingly, Gal-1's effects on mammary patterning were independent of its glycan-binding ability and instead required localization within the nuclei of mammary epithelia. Nuclear translocation of Gal-1, in turn, was regulated by discrete cell-surface glycans restricted to the front of the mammary end buds. Specifically, alpha2,6-sialylation of terminal LacNAc residues in the end buds masked Gal-1 ligands, thereby liberating the protein for nuclear translocation. Within mammary epithelia, Gal-1 localized within nuclear Gemini bodies and drove epithelial invasiveness. Conversely, unsialylated LacNAc glycans, enriched in the epithelial ducts, sequestered Gal-1 in the extracellular environment, ultimately attenuating invasive potential. We also found that malignant breast cells possess higher levels of nuclear Gal-1 and alpha2,6-SA and lower levels of LacNAc than nonmalignant cells in culture and in vivo and that nuclear localization of Gal-1 promotes a transformed phenotype. Our findings suggest that differential glycosylation at the level of tissue microanatomy regulates the nuclear function of Gal-1 in the context of mammary gland morphogenesis and in cancer progression. |
