Retrotransposon regulates photoperiodic spermatogenesis in Brandt’s
voles (Lasiopodomys brandtii) by co-transcription with flagellar genes
Abstract
Photoperiod is a pivotal factor in affecting spermatogenesis in
seasonal-breeding animals. Transposable elements, a class of DNA
sequences that can replicate and translocate in the genome, have
regulatory functions during spermatogenesis. However, whether it also
functions in photoperiodic spermatogenesis in seasonal breeding animals
is unknown. To explore this, we first annotated 5,501,822 transposons in
the whole genome of Brandt’s voles (Lasiopodomys brandtii), and revealed
that LINEs were the most abundant, comprising 16.61% of the genome.
Following closely, SINEs accounted for 10.13%, LTRs for 7.54%, and DNA
transposons for 0.70%. Insertion bias analysis revealed that 74.75% of
transposons were outside coding genes. Subsequently, we exposed male
Brandt’s voles to long-photoperiod (LP, 16 hours/day) and
short-photoperiod (SP, 8 hours/day) from their embryonic stages, and
obtained testes transcriptome at 4 and 10 weeks after birth.
Differential expression and Pearson analysis indicated strongly positive
correlations between the expression of differentially expressed
retrotransposons and the adjacent genes. KO, KEGG and GSEA results
showed that flagellar genes were key target genes regulated by
retrotransposons. RT-qPCR results validated the accuracy of the
transcriptome using randomly selected six genes (Dnah1, Axdnd1, Ccdc13,
Dnah17, Dnah2, Dnali1) and five transposons (LTR/ERVL-MaLR_113132,
LINE/L1_1811211, LINE/L1_69082, LINE/L1_662502, SINE/Alu_1213291).
RT-PCR results showed that SINE/Alu_1213291 regulates the
transcriptional expression of the Dnali1 gene. This study suggests that
transposon play a crucial role in the photoperiodic spermatogenesis in
Brandt’s voles, especially in the flagella assembly at the late
spermiogenesis. Our findings first reveal the regulatory function of
transposons in photoperiodic spermatogenesis, providing insights into
the role of photoperiod in seasonal reproduction in wild animals.