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.
Parris
James J
JJ
Department of Biological Sciences, University of Delaware, Newark, Delaware 19716, USA.
Cooke
Vesselina G
VG
Skarnes
William C
WC
Duncan
Melinda K
MK
Naik
Ulhas P
UP
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