An Assay for the Activity of Base Excision Repair Enzymes in Cellular Extracts Using Fluorescent DNA Probes

Area of Science:

• Molecular Biology
• Biochemistry
• Genetics

Background:

• The base excision repair (BER) pathway removes damaged DNA bases via DNA glycosylases and apurinic/apyrimidinic endonuclease 1 (APE1).
• Reduced BER enzyme activity is linked to increased risks of cardiovascular, neurodegenerative, and oncological diseases.
• Accurate measurement of BER enzyme activity is crucial for understanding disease mechanisms.

Purpose of the Study:

• To develop a novel fluorescence-based method for measuring the activity of key human DNA glycosylases and APE1.
• To apply this method to assess BER enzyme activity in various human cell extracts.
• To compare BER enzyme activity between cancer cell lines and a normal cell line.

Main Methods:

• Development and testing of fluorescent DNA probes for DNA glycosylase and APE1 activity.
• Enzymatic activity assays using purified human BER enzymes and fluorescent probes.
• Application of validated probes in cell extracts from A549, MCF7, HeLa, WT-7, HEK293T (cancer/immortalized) and HKC8 (normal kidney) cell lines.

Main Results:

• Optimized fluorescent DNA probes demonstrated efficacy in detecting BER enzyme activity.
• The developed method successfully measured activities of key BER enzymes in cell extracts.
• Cancer cell lines exhibited significantly higher activity of enzymes involved in AP site repair and uracil/dihydrouracil removal compared to the normal HKC8 cell line.

Conclusions:

• A sensitive fluorescence assay was established for quantifying BER enzyme activity in cellular contexts.
• Elevated activity of specific BER enzymes in cancer cells suggests their potential role in cancer progression.
• This method provides a valuable tool for future research into DNA repair mechanisms and disease pathogenesis.