posted on 2022-06-10, 21:04authored bySumirtha Balaratnam, Mohammed Enamul Hoque, Nicole West, Soumitra Basu
Piwi-interacting RNAs (piRNAs) are
a group of small noncoding RNA
molecules that regulate the activity of transposons and control gene
expression. The cellular concentration of RNAs is generally maintained
by their rates of biogenesis and degradation. Although the biogenesis
pathways of piRNAs have been well defined, their degradation mechanism
is still unknown. Here, we show that degradation of human piRNAs is
mostly dependent on the 5′–3′ exoribonuclease
pathway. The presence of 3′-end 2′-O-methylation in piRNAs significantly reduced their degradation through
the exosome-mediated decay pathway. The accumulation of piRNAs in
XRN1 and XRN2 exoribonuclease-depleted cells further supports the
5′–3′ exoribonuclease-mediated decay of piRNAs.
Moreover, formation of stable secondary structures in piRNAs slows
the rate of XRN1-mediated degradation. Our findings establish a framework
for the piRNA degradation mechanism in cells and thus provide crucial
information about how the basal level concentration of piRNAs is maintained
in cells.