Mechanisms of MAdCAM-1 gene expression in human intestinal microvascular endothelial cells.
Mucosal addressin cell adhesion molecule-1 (MAdCAM-1) is a homing receptor preferentially expressed on gut-associated endothelial cells that plays a central role in leukocyte traffic into the mucosal immune compartment. Although the molecular mechanisms underlying endothelial ICAM-1 or E-selectin expression have been intensively investigated, the mechanisms that regulate human MAdCAM-1 expression have not been defined. We report MAdCAM-1 gene and protein expression in primary cultures of human intestinal microvascular endothelial cells (HIMEC) that was not demonstrated in human umbilical vein endothelial cells. Similar to ICAM-1 and E-selectin expression, MAdCAM-1 gene expression in HIMEC was inducible with TNF-alpha, IL-1beta, or LPS activation. However, in striking contrast to ICAM-1 and E-selectin expression, MAdCAM-1 mRNA and protein expression in HIMEC was heavily dependent on culture duration and/or cellular density, suggesting a prominent role for cell-cell interaction among these endothelial cells in the expression of the mucosal addressin. MAdCAM-1 expression was inhibited by both SN-50 (NF-kappaB inhibitor) and LY-294002 [phosphatidylinositol 3-kinase (PI3-K) inhibitor], whereas ICAM-1 and E-selectin expression was inhibited by SN-50 but not by LY-294002. The Akt phosphorylation by TNF-alpha or LPS was greater at higher cell density, demonstrating a pattern similar to that of MAdCAM-1 expression. NF-kappaB activation was not affected by cellular density in HIMEC. MAdCAM-1 expression in human gut endothelial cells is regulated by distinct signaling mechanisms involving both NF-kappaB and PI3-K/Akt. These data also suggest that PI3-K/Akt is involved in the gut-specific differentiation of HIMEC, which results in expression of the mucosal addressin MAdCAM-1.
Division of Gastroenterology and Hepatology, Froedtert Memorial Lutheran Hospital, Milwaukee Veterans Administration Medical Center, Medical College of Wisconsin, USA.
Hitoshi
H
Ogawa
David G
DG
Binion
Jan
J
Heidemann
Monica
M
Theriot
Pamela J
PJ
Fisher
Nathan A
NA
Johnson
Mary F
MF
Otterson
Parvaneh
P
Rafiee
D000954:Antigens, Surface / Q000235:genetics* / Q000378:metabolism; D015153:Blotting, Western; D015815:Cell Adhesion Molecules; D002478:Cells, Cultured; D019040:E-Selectin / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D042783:Endothelial Cells / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D006801:Humans; D007136:Immunoglobulins; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D007413:Intestinal Mucosa / Q000098:blood supply* / Q000378:metabolism; D008565:Membrane Proteins; D009088:Mucoproteins; D016328:NF-kappa B / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D012333:RNA, Messenger; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*
D000954:Antigens, Surface; D015815:Cell Adhesion Molecules; D019040:E-Selectin; D007136:Immunoglobulins; D018799:Intercellular Adhesion Molecule-1; D008565:Membrane Proteins; D009088:Mucoproteins; D016328:NF-kappa B; D019869:Phosphatidylinositol 3-Kinases; D012333:RNA, Messenger; C069886:L-selectin counter-receptors; C504265:MADCAM1 protein, human