Intracellular precursor interleukin (IL)-1alpha, but not mature IL-1alpha, is able to regulate human endothelial cell migration in vitro.
The human umbilical vein endothelial cell (HUVEC) has a finite lifespan in vitro, and senescent HUVEC contain elevated levels of the negative growth regulator interleukin (IL)-1alpha. IL-1alpha is translated as a signal peptide sequence-less cytosolic 31-kDa precursor (IL-1alpha p), which undergoes proteolytic activation to release the mature carboxyl terminus 17-kDa protein (IL-1alpha m). Both the IL-1alpha p and IL-1alpha m proteins are biologically active as exogenous cytokines. Interestingly, only IL-1alpha p contains a nuclear localization sequence between residues 79 and 85. To further study the role of intracellular IL-1alpha in the regulation of human endothelial cell function, a spontaneous HUVEC transformant was stably transfected with IL-1alpha p, IL-1alpha m, and the IL-1alpha p K82N mutant, which attenuates the nuclear traffic of IL-1alpha p. Interestingly, the IL-1alpha p transfectants were found to have a lower migratory potential than either IL-1alpha m or IL-1alpha p K82N transfectants, and the addition of the IL-1 receptor antagonist did not alter the migration of these cells. Immunofluorescence microscopy demonstrated that only the IL-1alpha p transfectants exhibited prominent staining for beta-catenin-associated cell-to-cell contacts, as well as pronounced vimentin intermediate filaments and actin cytoskeleton staining. These data suggest that IL-1alpha p, and not IL-1alpha m, may function as an intracellular regulator of the migratory capacity of the human endothelial cell and that the nuclear localization sequence present within IL-1alpha p may be involved in regulating this function.
McMahon
G A
GA
Department of Molecular Biology, Holland Laboratory, American Red Cross, Rockville, Maryland 20855, USA.
Garfinkel
S
S
Prudovsky
I
I
Hu
X
X
Maciag
T
T
D002465:Cell Movement / Q000502:physiology; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology*; D006801:Humans; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1 / Q000235:genetics / Q000502:physiology*; D011498:Protein Precursors / Q000235:genetics / Q000502:physiology*; D017472:Receptors, Interleukin-1 / Q000037:antagonists & inhibitors; D011994:Recombinant Proteins / Q000494:pharmacology; D012795:Sialoglycoproteins / Q000494:pharmacology; D014162:Transfection
C507763:IL1RN protein, human; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1; D011498:Protein Precursors; D017472:Receptors, Interleukin-1; D011994:Recombinant Proteins; D012795:Sialoglycoproteins; C043830:interleukin 1 precursor