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Title: Phorbol diesters and transferrin modulate lymphoblastoid cell transferrin receptor expression by two different mechanisms

Expression of transferrin receptors (TfR) by activated lymphocytes is necessary for lymphocyte DNA synthesis and proliferation. Regulation of TfR expression, therefore, is a mechanism by which the lymphocyte's proliferative potential may be directed and controlled. The authors studied mechanisms by which lymphoblastoid cells modulate TfR expression during treatment with phorbol diesters or iron transferrin (FeTf), agents which cause downregulation of cell surface TfR. Phorbol diester-induced TfR downregulation occurred rapidly, being detectable at 2 min and reaching maximal decreases of 50% by 15 min. It was inhibited by cold but not by agents that destabilize cytoskeletal elements. Furthermore, this downregulation was reversed rapidly by washing or by treatment with the membrane interactive agent, chlorpromazine. In contrast, FeTf-induced TfR downregulation occurred slowly. Decreased expression of TfR was detectable only after 15 min and maximal downregulation was achieved after 60 min. Although FeTf-induced downregulation also was inhibited by cold, it was inhibited in addition by a group of microtubule destabilizing agents (colchicine, vinblastine, podophyllotoxin) or cytochalasin B, a microfilament inhibitor. Furthermore, FeTf-induced downregulation was not reversed readily by washing or by treatment with chlorpromazine. Phorbol diesters cause TfR downregulation by a cytoskeleton-independent mechanism. These data indicate that TfR expression is regulated by twomore » independent mechanisms in lymphoblastoid cells, and they provide the possibility that downregulation of TfR by different mechanisms may result in different effects in these cells.« less
Authors:
; ;
Publication Date:
OSTI Identifier:
6790275
Resource Type:
Journal Article
Resource Relation:
Journal Name: J. Cell. Physiol.; (United States); Journal Volume: 129:3
Research Org:
Univ. of Texas Health Science Center, San Antonio
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; MONOCLONAL ANTIBODIES; RADIORECEPTOR ASSAY; PHORBOL ESTERS; BIOCHEMISTRY; TRANSFERRIN; DNA REPLICATION; GROWTH; INHIBITION; IODINE 125; LYMPHOCYTES; RECEPTORS; ANIMAL CELLS; ANTIBODIES; BETA DECAY RADIOISOTOPES; BIOLOGICAL MATERIALS; BLOOD; BLOOD CELLS; BODY FLUIDS; CARCINOGENS; CHEMISTRY; CONNECTIVE TISSUE CELLS; DAYS LIVING RADIOISOTOPES; ELECTRON CAPTURE RADIOISOTOPES; ESTERS; GLOBULINS; GLOBULINS-BETA; INTERMEDIATE MASS NUCLEI; IODINE ISOTOPES; ISOTOPE APPLICATIONS; ISOTOPES; LEUKOCYTES; MATERIALS; MEMBRANE PROTEINS; METALLOPROTEINS; NUCLEI; NUCLEIC ACID REPLICATION; ODD-EVEN NUCLEI; ORGANIC COMPOUNDS; PROTEINS; RADIOISOTOPES; SOMATIC CELLS; TRACER TECHNIQUES 550601* -- Medicine-- Unsealed Radionuclides in Diagnostics