Angiogenin is a cytotoxic, tRNA-specific ribonuclease in the RNase A superfamily

Area of Science:

• Biochemistry
• Molecular Biology
• Cell Biology

Background:

• Angiogenin is a human plasma protein homologous to RNase A.
• It shares key active site residues and disulfide bonds with RNase A.

Purpose of the Study:

• To investigate the enzymatic activity and cytotoxic effects of angiogenin.
• To determine if angiogenin specifically targets tRNA and its role in protein synthesis inhibition.

Main Methods:

• Recombinant angiogenin was used in cell-free lysates and Xenopus oocytes.
• Protein synthesis inhibition and tRNA degradation were measured.
• RNase inhibitor RNasin and exogenous tRNAs were used to assess reversibility.

Main Results:

• Angiogenin functions as a cytotoxic tRNA-specific ribonuclease.
• Protein synthesis inhibition by angiogenin correlates with tRNA degradation.
• Exogenous tRNA restored protein synthesis, confirming tRNA degradation as the cause of cytotoxicity.
• Angiogenin homologues, like eosinophil-derived neurotoxin, lack tRNA specificity and are broadly cytotoxic.

Conclusions:

• Angiogenin is a specific cellular tRNase responsible for protein synthesis inhibition via tRNA degradation.
• Its specificity distinguishes it from other RNase A superfamily members.
• Understanding angiogenin's tRNase activity is crucial for its biological roles.