(2'-5')Oligoadenylate in rat liver: modulation after partial hepatectomy.

Area of Science:

• Biochemistry
• Molecular Biology
• Cellular Biology

Background:

• (2 -5 )Oligoadenylate synthetase [(2 -5 )A synthetase] synthesizes oligoadenylates (2 -5 )A.
• This enzyme's activity decreases during early rat liver regeneration.
• Double-stranded RNA, an activator of (2 -5 )A synthetase, is found in rat liver nuclei.

Purpose of the Study:

• To confirm the presence and characterize (2 -5 )A oligonucleotides in rat liver cells.
• To investigate the relationship between (2 -5 )A synthetase activity and intracellular (2 -5 )A concentration during liver regeneration.
• To explore the physiological role of the (2 -5 )A system in cell proliferation.

Main Methods:

• High-performance liquid chromatography (HPLC) coupled with an endonuclease-based radiobinding assay.
• Characterization of synthesized oligonucleotides using alkaline phosphatase, snake venom phosphodiesterase, and micrococcal nuclease.
• Measurement of (2 -5 )A synthetase activity and intracellular (2 -5 )A concentration during rat liver regeneration.

Main Results:

• Oligonucleotides indistinguishable from authentic (2 -5 )A were detected in rat liver cells.
• A decrease in (2 -5 )A synthetase activity during liver regeneration correlated with a decrease in intracellular (2 -5 )A concentration.
• The kinetics of (2 -5 )A synthesis mirrored the enzyme's activity, with a sharp decrease between 6-20 hr post-hepatectomy and a minimum at 20-24 hr.

Conclusions:

• The (2 -5 )A system is naturally occurring in rat liver cells.
• The (2 -5 )A system's concentration dynamically changes during liver regeneration, mirroring enzyme activity.
• These findings support a physiological role for the (2 -5 )A system in regulating cell proliferation and differentiation.