Morphological change and destabilization of beta-actin mRNA by tumor necrosis factor in human microvascular endothelial cells.
Tumor necrosis factor-alpha (TNF-alpha) produced morphological changes from a cobblestone-like shape into a spindle shape in human omental microvascular endothelial (HOME) cells and also a drastic rearrangement of actin filaments. Expression of beta-actin gene was diminished in HOME cells treated with TNF-alpha for 24 h. Northern blot analysis of the beta-actin gene demonstrated that the cellular level of beta-actin mRNA was decreased at 6-12 h after exposure to TNF-alpha. However, there appeared to be no changes in cellular mRNA levels of beta-tubulin, fibronectin, laminin B1, laminin B2, and laminin binding protein genes after treatment with TNF-alpha. Nuclear run-on assays showed increased transcription of the low-density lipoprotein receptor gene, but not of the beta-actin gene. These data suggested that the TNF-alpha-induced inhibition of beta-actin gene expression was not due to altered transcription activity. The degradation rates of beta-actin, plasminogen activator inhibitor-1, and epidermal growth factor receptor mRNAs were examined in the presence of actinomycin D. beta-Actin mRNA was found to be specifically destabilized in TNF-alpha-treated HOME cells, while other mRNA species were not. Coadministration of cycloheximide blocked the TNF-alpha-induced degradation of beta-actin mRNA. The TNF-alpha-induced destabilization of beta-actin mRNA and rearrangement of actin filaments are discussed in relation to the morphological changes in human microvascular endothelial cells.
Department of Biochemistry, Oita Medical University, Japan.
K
K
Kohno
R
R
Hamanaka
T
T
Abe
Y
Y
Nomura
A
A
Morimoto
H
H
Izumi
K
K
Shimizu
M
M
Ono
M
M
Kuwano
D008841:Actin Cytoskeleton / Q000648:ultrastructure; D000199:Actins / Q000235:genetics*; D003598:Cytoskeletal Proteins / Q000235:genetics; D004730:Endothelium, Vascular / Q000378:metabolism*; D016326:Extracellular Matrix Proteins / Q000235:genetics; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D012333:RNA, Messenger / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D000199:Actins; D003598:Cytoskeletal Proteins; D016326:Extracellular Matrix Proteins; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha