title: Expression of the homotypic adhesion molecule E-cadherin by immature murine thymocytes and thymic epithelial cells.
abstract: Cadherins mediate homotypic adhesion between lineage-related cells in epithelia and other tissues. One cadherin, E-cadherin, is also responsible for adhesion of murine epidermal Langerhans cells to keratinocytes in vitro, and may play a role in the localization of Langerhans cells in epidermis. The thymus is another tissue in which important adhesive interactions between bone marrow-derived cells and keratinizing epithelia occur. To determine whether cadherins might be involved in interactions between thymocytes and thymic epithelial cells, we examined thymocytes from C57BL/6 mice of various gestational ages for cadherin expression. Most day 14 (D14) and essentially all D16 isolated fetal thymocytes expressed cell surface E-cadherin. After D16, the proportion of fetal thymocytes expressing E-cadherin and the level of E-cadherin expressed by individual thymocytes decreased with increasing gestational age. A minority of neonatal thymocytes and very few adult thymocytes expressed E-cadherin. E-cadherin was maximally expressed by the least mature (CD4-CD8-, HSA (J11d)high, CD5 (Ly-1)low, CD25 (IL-2R alpha)+) thymocytes. P-cadherin, another epithelial cadherin, was not detected on thymocytes at any stage of development. Immunohistologic studies revealed that thymic epithelial cells also expressed E-cadherin. Similar levels of E-cadherin were expressed by neonatal and adult thymic epithelial cells in situ, and E-cadherin was easily demonstrable on the thymic epithelial cell line, TE-71. In contrast, P-cadherin was transiently expressed by thymic epithelial cells in situ, and only small amounts of P-cadherin were detected on TE-71 cells. These studies demonstrate that thymocytes and thymic epithelial cells each have the capacity to express the homotypic adhesion molecule E-cadherin. E-cadherin may play a role in developmentally regulated interactions between early thymocytes and thymic stromal cells.
authors.affiliation: Dermatology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.
authors.forename: M G
authors.initials: MG
authors.lastname: Lee
authors.forename: S O
authors.initials: SO
authors.lastname: Sharrow
authors.forename: A G
authors.initials: AG
authors.lastname: Farr
authors.forename: A
authors.initials: A
authors.lastname: Singer
authors.forename: M C
authors.initials: MC
authors.lastname: Udey
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D015820:Cadherins / Q000096:biosynthesis / Q000378:metabolism*; D002450:Cell Communication; D002454:Cell Differentiation; D004847:Epithelial Cells; D004848:Epithelium / Q000378:metabolism; D005260:Female; D005333:Fetus / Q000166:cytology / Q000378:metabolism; D005865:Gestational Age; D051379:Mice; D008810:Mice, Inbred C57BL; D010641:Phenotype; D011247:Pregnancy; D013601:T-Lymphocytes / Q000166:cytology / Q000378:metabolism*; D013950:Thymus Gland / Q000166:cytology / Q000378:metabolism
chemical_list: D015820:Cadherins