Abstract
PIWI-interacting RNAs (piRNAs) and the subgroup of argonaute (AGO) proteins that collaborate with PIWI proteins are essential for cell repair, heterochromatin modifications, and PIWI-dependent transposon silencing. The genome stability of somatic and germ cells is maintained by small noncoding RNAs called piRNAs, which are also essential for transposon silencing. It is thought that during gametogenesis, PIWI proteins and piRNAs protect the gamete's genome stability. In the present study, isolated cumulus cells from follicular fluid (FF) were used to assess the expression of the PIWIL3 gene and the piR-651, piR-823, and piR-16993 between normoresponder (NOR) and diminished ovarian reserve (DOR) cases. According to the data, no statistically significant result was observed in piR-651 expression in DOR. Conversely, the DOR group's expression of piR-823 and piR-16993 decreased compared to the NOR (P < 0.05). While no correlation was observed between piRNAs and PIWIL3 gene in the NOR, there was strong correlation between piR-651 and piR-16993 (r < 0.05) and weak correlation between piR-823 and both piR-16993 and PIWIL3 gene in the DOR group (r < 0.01). The profile of piR-16993 expression, which is effective in cell proliferation, brings to light for the first time in humans the molecular mechanism of piRNA that is specific to DOR cases (Graphical Abstract) .