Piwi-Pathway Alteration Induces LINE-1 Transposon Derepression and Infertility Development in Cryptorchidism

Spermatogonia contain processing bodies that harbor P-element-induced wimpy testis (Piwi) proteins. Piwi proteins are associated specifically with Piwi-interacting RNAs to si-lence transposable DNA elements. Loss-of-function mutations in the Piwi pathway lead to derepression of transposable elements, resulting in defective spermatogenesis.


Spermatogonia contain processing bodies that harbor P-el-ement-induced wimpy testis (Piwi) proteins. Piwi proteinsare associated specifically with Piwi-interacting RNAs to si-lence transposable DNA elements. Loss-of-function muta-tions in the Piwi pathway lead to derepression of transpos-able elements, resulting in defective spermatogenesis. Fur-thermore, deletion of gametocyte-specific factor 1 (GTSF1),a factor involved in Piwi-mediated transcriptional repres-sion, causes male-specific sterility and derepression of LINE-1 (L1) retrotransposons. No previous studies have examinedGTSF1, L1 and PIWIL4 expression in cryptorchidism. We ex-amined transposon-silencing genes and L1 transposon ex-pression in testicular biopsies with Affymetrix microarraysand immunohistology. Seven members of the Tudor genefamily, 3 members of the DEAD-box RNA helicase family, andthe GTSF1 gene were found to show significantly lower RNAsignals in the high-infertility-risk group.
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