These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Thyroid hormone analogues potentiate the antiviral action of interferon-gamma by two mechanisms.
    Author: Lin HY, Thacore HR, Davis FB, Davis PJ.
    Journal: J Cell Physiol; 1996 May; 167(2):269-76. PubMed ID: 8613467.
    Abstract:
    L-thyroxine (L-T4) potentiates the antiviral activity of human interferon-gamma (IFN-gamma) in HeLa cells. We have added thyroid hormone and analogues to cells either 1) for 24 h pretreatment prior to 24 h of IFN-gamma (1.0 IU/ml), 2) for 24 h cotreatment with IFN-gamma, 3) for 4, after 20 h cell incubation with IFN-gamma, alone, or 4) for 24 h pretreatment and 24 h cotreatment with IFN-gamma. The antiviral effect of IFN-gamma was then assayed. L-T4 potentiated the antiviral action of IFN-gamma by a reduction in virus yield of more than two logs, the equivalent of a more than 100-fold potentiation of the IFN's antiviral effect. 3,3 of the IFN's antiviral effect. 3,3',5-L-triiodothyronine (L-T3) was as effective as L-T4 when coincubated for 24 h with IFN-gamma but was less effective than L-T4 when coincubated for only 4 h. D-T4, D-T3, 3,3',5-triiodothyroacetic acid (triac), tetraiodothyroacetic acid (tetrac), and 3,5-diiodothyronine (T2) were inactive. When preincubated with L-T4 for 24 h prior to IFN-gamma treatment, tetrac blocked L-T4 potentiation, but, when coincubated with L-T4 for 4 h after 20 h IFN-gamma, tetrac did not inhibit the L-T4 effect. 3,3',5-L-triiodothyronine (rT3) also potentiated the antiviral action of IFN-gamma, but only in the preincubation model. Furthermore, the effects of rT3 preincubation and L-T3 coincubation were additive, resulting in 100-fold potentiation of the IFN-gamma effect. When L-T4, L-T3, or rT3, plus cycloheximide (5 micrograms/ml), was added to cells for 24 h and then removed prior to 24 h IFN-gamma exposure, the potentiating effect of the three iodothyronines was completely inhibited. In contrast, IFN-gamma potentiation by 4 h of L-T4 or L-T3 coincubation was not inhibited by cycloheximide (25 micrograms/ml). These studies demonstrate two mechanisms by which thyroid hormones can potentiate IFN-gamma's effect: 1) a protein synthesis-dependent mechanism evidenced by enhancement of IFN-gamma's antiviral action by L-T4, L-T3, or rT3 preincubation, and inhibition of enhancement by tetrac and cycloheximide, and 2) a protein synthesis-independent (posttranslational) mechanism, not inhibited by tetrac or cycloheximide, demonstrated by 4 h coincubation of L-T4 or L-T3, but not rT3, with IFN-gamma. The protein synthesis-dependent pathway is responsive to rT3, a thyroid hormone analogue generally thought to have little effect on protein synthesis. A posttranslational mechanism by which the antiviral action of IFN-gamma can be regulated has not previously been described.
    [Abstract] [Full Text] [Related] [New Search]