RNA Labeling for Measuring RNA Endonucleolytic Cleavage

Although endonucleolytic cleavage of RNA is an essential process for maintaining cellular RNA homeostasis, its detection and quantification are often challenging. In this chapter, we present methods for detecting and quantifying RNA endonucleolytic cleavage events using Northern blot analysis. We describe two RNA labeling strategies for probe preparation: (1) a radiolabeled probe generated by 5' end-labeling with [γ-³²P]ATP and polynucleotide kinase, and (2) a nonradioactive probe labeled with digoxigenin (DIG) or biotin for chemiluminescent detection. RNA samples are resolved by gel electrophoresis and transferred to a membrane. The labeled probes are then hybridized to the blotted RNA to detect specific cleavage products. These protocols enable both qualitative assessment of cleavage patterns and quantitative measurement of cleavage efficiency. We include step-by-step procedures from probe labeling to detection of target RNAs, as well as optional modifications to improve sensitivity and specificity. The methods are broadly applicable to analyzing RNA cleavage by various nucleases, providing a reliable combination of sensitivity for different experimental needs.