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Interferon-mediated inhibition of adenylate cyclase in mouse cells
Abstract:
Adenylate cyclase activity was measured in mouse cell plasma membrane after 30 units/ml of interferon (IFN) treatment. The basal and Gpp(NH)p stimulated enzyme activity in LB cell was inhibited by 20%-40% throughout the time course of treatment (30 min to 18 h). The reduced enzyme activity was not associated with enhanced breakdown of cAMP, but was related to alteration in the catalytic component of the enzyme. Moreover, there was no change in the affinity for guanine-nucleotide regulatory unit and 1 X 10(-7) M Gpp(NH)p was required to obtain half-maximal activation with either type of membrane. Interferon action on adenylate cyclase was biphasic, at 10 u/ml it was stimulatory and between 30 and 1000 u/ml it inhibited the enzyme activity to a great extent; but IFN did not exert its effect directly on the enzyme. The reduction in enzyme activity was comparable to a reduction in the intracellular level of cAMP in most of the interferon-sensitive cell lines studied. We propose, therefore, that the inhibitory effect on adenylate cyclase is related to a step in the development of antiviral activity.
Insights
Interferon (IFN) inhibits adenylate cyclase activity in mouse cells, reducing cyclic AMP (cAMP) levels. This enzyme inhibition is linked to the development of antiviral activity, suggesting a key mechanism of interferon
Area of Science:
- Biochemistry
- Cell Biology
- Immunology
Background:
- Interferon (IFN) is crucial for antiviral defense.
- Adenylate cyclase regulates intracellular cyclic AMP (cAMP) levels.
- Understanding IFN's molecular mechanisms is vital for antiviral research.
Purpose of the Study:
- To investigate the effect of interferon (IFN) on adenylate cyclase activity in mouse cells.
- To elucidate the mechanism by which IFN modulates enzyme activity and cAMP levels.
- To explore the relationship between IFN-induced adenylate cyclase inhibition and antiviral effects.
Main Methods:
- Measurement of adenylate cyclase activity in mouse cell plasma membranes.
- Treatment with varying concentrations of interferon (IFN) over time.
- Analysis of basal and Gpp(NH)p-stimulated enzyme activity.
- Assessment of cAMP breakdown and enzyme kinetics.
Main Results:
- Interferon (IFN) at 30 units/ml inhibited both basal and Gpp(NH)p-stimulated adenylate cyclase activity by 20%-40%.
- Inhibition was linked to alterations in the enzyme's catalytic component, not increased cAMP breakdown or altered affinity for regulatory units.
- IFN's effect was biphasic: stimulatory at 10 u/ml and inhibitory at higher concentrations (30-1000 u/ml).
- Reduced adenylate cyclase activity correlated with decreased intracellular cAMP levels in IFN-sensitive cell lines.
Conclusions:
- Interferon (IFN) significantly inhibits adenylate cyclase activity in mouse cells.
- The inhibitory effect on adenylate cyclase is a key step in the development of interferon's antiviral activity.
- IFN does not directly affect the enzyme but influences its catalytic component, leading to reduced cAMP production.