Bowhead NEIL1: molecular cloning, characterization, and enzymatic properties

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Nei Like DNA Glycosylase 1 (NEIL1) is crucial for repairing oxidative DNA damage via base excision repair.
• NEIL1 removes oxidized pyrimidines caused by endogenous or exogenous agents.
• NEIL1 possesses both glycosylase and AP-lyase activities for DNA backbone cleavage.

Purpose of the Study:

• To investigate if enhanced NEIL1 activity or upregulation contributes to the cancer resistance observed in bowhead whales.
• To characterize bowhead whale NEIL1, including its transcript variants and enzymatic function.

Main Methods:

• Molecular cloning and characterization of bowhead whale NEIL1 transcript variants.
• Differential expression analysis of NEIL1 mRNA in various bowhead whale tissues.
• Investigation of A-to-I RNA editing in bowhead whale NEIL1.
• Mass spectrometry to detect potential RNA editing-derived isoforms.
• Expression and enzymatic activity assays of recombinant bowhead and human NEIL1.

Main Results:

• Three bowhead whale NEIL1 transcript variants were identified, two homologous to human and one novel.
• Differential NEIL1 mRNA expression was observed across bowhead whale tissues.
• Conserved A-to-I editing occurred in the bowhead whale NEIL1, but no editing-derived isoform was detected via mass spectrometry.
• Recombinant bowhead and human NEIL1 exhibited similar efficiency in removing 5-hydroxyuracil DNA lesions.

Conclusions:

• The study's findings do not support the hypothesis that increased NEIL1 activity or expression confers cancer resistance in bowhead whales.
• The enzymatic activity of bowhead whale NEIL1 is comparable to human NEIL1.
• While the hypothesis is not supported, it is not entirely refuted, suggesting other DNA repair mechanisms may be involved.