Aberrant Expression of TET2 Accounts for DNA Hypomethylation in Varicocele

Document Type : Original Article


1 ACECR Institute of Higher Education, Isfahan Branch, Isfahan, Iran

2 Department of Animal Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran

3 Department of Animal Biotechnology, Cell Science Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran


Objective: Epigenetic modifications such as DNA methylation play a key role in male infertility etiology. This study aimed
to explore the global DNA methylation status in testicular spermatogenic cells of varicocele-induced rats and consider
their semen quality, with a focus on key epigenetic marks, namely 5-methylcytosine (5-mC) and 5-hydroxymethylcytosine
(5-hmC), as well as the mRNA and proteins of ten-eleven translocation (TET) methylcytosine dioxygenases 1-3.
Materials and Methods: In this experimental study, 24 mature male Wistar rats (8 in each group) were assigned
amongst the control, sham, and varicocele groups. Sperm quality was assessed, and DNA methylation patterns of
testicular spermatogenic cells were investigated using reverse transcription-polymerase chain reaction (RT-PCR),
western blot, and immunofluorescence techniques.
Results: Sperm parameters, chromatin and DNA integrity were significantly lower, and sperm lipid peroxidation significantly
increased in varicocele-induced rats in comparison with control rats. During spermatogenesis in rat testis, 5-mC and 5-hmC
epigenetic marks, and TET1-3 mRNA and proteins were expressed. In contrast to the 5-mC fluorescent signal which was
presented in all testicular cells, the 5-hmC fluorescent signal was presented exclusively in spermatogonia and a few spermatids.
In varicocele-induced rats, the 5-mC signal decreased in all cells within the tubules, whereas a strong signal of 5-hmC was
detected in seminiferous tubules compared to the control group. As well, the levels of TET2 mRNA and protein expression
were significantly upregulated in varicocele-induced rats in comparison with the control group. Also, our results showed that
the varicocele-induced animals exhibited strong fluorescent signals of TET1-3 in testicular cells, whereas weak fluorescent
signals were identified in the seminiferous tubules of the control animals.
Conclusion: Consequently, we showed TET2 upregulation and the 5-hmC gain at testicular levels are associated with
varicocele and sperm quality decline, and therefore they can be exploited as potential biomarkers of spermatogenesis.


Main Subjects

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