JAM-A expression during embryonic development.
Cell adhesion molecules of the immunoglobulin superfamily play an important role in embryonic development. We have shown recently that JAM-A, a member of this family expressed at endothelial and epithelial tight junctions, is involved in platelet activation, leukocyte transmigration, and angiogenesis. Here, we determine the expression pattern of the JAM-A gene during embryogenesis using transgenic mice expressing lacZ under the control of the endogenous JAM-A promoter. Histochemical staining for beta-galactosidase in heterozygous mouse embryos was first seen in the inner cell mass and trophectoderm of the blastocyst. By 8.5 days post coitum (dpc), JAM-A gene activity was detected in the endoderm and part of the surface ectoderm. At 9.5 dpc, JAM-A expression began to localize to certain organ systems, most notably the developing inner ear and early vasculature. Localization of JAM-A to embryonic vasculature was confirmed by double-staining with antibodies against JAM-A and platelet endothelial cell adhesion molecule-1, a known endothelial cell marker. As organogenesis progressed, high levels of JAM-A expression continued in the epithelial component of the inner ear as well as the epithelium of the developing skin, olfactory system, lungs, and kidneys. In addition, JAM-A gene activity was found in the developing liver, choroid plexuses, and gut tubes. Immunofluorescent staining with a JAM-A antibody was performed to confirm that expression of the JAM-A-beta-galactosidase fusion protein accurately represented endogenous JAM-A protein. Thus, JAM-A is prominently expressed in embryonic vasculature and the epithelial components of several organ systems and may have an important role in their development.
Department of Biological Sciences, University of Delaware, Newark, Delaware 19716, USA.
James J
JJ
Parris
Vesselina G
VG
Cooke
William C
WC
Skarnes
Melinda K
MK
Duncan
Ulhas P
UP
Naik
D000818:Animals; D015815:Cell Adhesion Molecules / Q000096:biosynthesis* / Q000235:genetics*; D004622:Embryo, Mammalian / Q000378:metabolism / Q000502:physiology*; D004848:Epithelium / Q000196:embryology / Q000378:metabolism; D005121:Extremities / Q000098:blood supply / Q000196:embryology*; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D016254:Mutagenesis, Insertional; D011956:Receptors, Cell Surface / Q000096:biosynthesis* / Q000235:genetics*; D012679:Sense Organs / Q000196:embryology / Q000378:metabolism; D019108:Tight Junctions / Q000378:metabolism
D015815:Cell Adhesion Molecules; C498686:F11r protein, mouse; D011956:Receptors, Cell Surface