Sex-specific promoters regulate Dnmt3L expression in mouse germ cells.

Area of Science:

• Epigenetics and Gene Regulation
• Reproductive Biology
• Genomics

Background:

• DNA methyltransferase 3-like (Dnmt3L) lacks enzymatic activity but is crucial for de novo methylation of imprinted genes in oocytes and transposon repression in male germ cells.
• Understanding Dnmt3L's role is vital for comprehending germ cell development and epigenetic inheritance.

Purpose of the Study:

• To identify and characterize the various Dnmt3L transcripts during germ cell development.
• To elucidate the regulatory mechanisms controlling Dnmt3L expression in male and female germ cells.

Main Methods:

• Utilized northern blots, RT-PCR, 5' RACE, RNase H mapping, real-time/quantitative RT-PCR, and in situ hybridization.
• Investigated Dnmt3L transcript profiles across different stages of mouse and human germ cell development.

Main Results:

• Mouse Dnmt3L expression is driven by three distinct sex-specific promoters, contrary to previous assumptions of a single promoter.
• A promoter in prospermatogonia drives full-length Dnmt3L mRNA in perinatal testis, essential for de novo methylation.
• Oocytes utilize an oocyte-specific promoter within the neighboring Aire gene, producing a transcript with a full open reading frame (ORF).

Conclusions:

• Sex-specific promoters precisely control Dnmt3L expression in the mouse germline, a mechanism also observed for Dnmt1 and Dnmt3A.
• These findings reveal complex transcriptional regulation of Dnmt3L, essential for its functions in both male and female germ cells.