Cell adhesion regulates gene expression at translational checkpoints in human myeloid leukocytes.
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ABSTRACT: Engagement of adhesion molecules on monocytes and other myeloid leukocytes, which are effector cells of the innate immune system, not only tethers the leukocytes in place but also transmits outside-in signals that induce functional changes and alter gene expression. We found that a subset of mRNAs that are induced or amplified by adhesion of human monocytes to P-selectin via its surface ligand, P-selectin glycoprotein 1, have characteristics that suggest specialized translational control. One of these codes for urokinase plasminogen activator receptor (UPAR), a critical surface protease receptor and regulator of cell adhesion and migration. Although UPAR transcripts are induced by adhesion, rapid synthesis of the protein uses constitutive mRNA without a requirement for new transcription and is regulated by mammalian target of rapamycin, demonstrating new biologic roles for the signal-dependent translation pathway controlled by this intracellular kinase. The synthesis of UPAR in monocytic cells is also regulated by eukaryotic translation initiation factor 4E, a second key translational checkpoint, and phosphorylation of eukaryotic translation initiation factor 4E is induced by adhesion of monocytes to P-selectin. Translationally controlled display of UPAR by monocytes confers recognition of the matrix protein, vitronectin. Adhesion-dependent signaling from the plasma membrane to translational checkpoints represents a previously unrecognized mechanism for regulating surface phenotype that may be particularly important for myeloid leukocytes and other cells that are specialized for rapid inflammatory and vascular responses.
SUBMITTER: Mahoney TS
PROVIDER: S-EPMC56953 | biostudies-literature | 2001 Aug
REPOSITORIES: biostudies-literature
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