Two bromodomain proteins functionally interact to recapitulate an essential BRDT-like function in Drosophila...

Area of Science:

• Reproductive Biology
• Molecular Genetics
• Cell Biology

Background:

• The Bromodomain and Extra Terminal (BET) protein BRDT is crucial for mammalian spermatogenesis.
• Drosophila tBRD-1, a testis-specific bromodomain protein, is required for male fertility but lacks the Extra Terminal (ET) domain characteristic of BET proteins.

Purpose of the Study:

• To identify novel proteins interacting with Drosophila tBRD-1.
• To characterize the function of a newly identified testis-specific bromodomain protein, tBRD-2, in Drosophila male reproduction.

Main Methods:

• Proteomics approaches were employed to identify tBRD-1 interactors.
• Knock-out studies were performed to assess the function of tbrd-2.
• Immunofluorescence microscopy was used to examine protein co-localization and interdependence in spermatocytes.

Main Results:

• A novel testis-specific bromodomain protein, tBRD-2, was identified as a tBRD-1 interactor.
• tBRD-2 possesses a single bromodomain and an ET domain, unlike tBRD-1.
• tbrd-2 knock-out males exhibit sterility and aberrant meiosis, phenotypically similar to tbrd-1 mutants.
• tBRD-1 and tBRD-2 co-localize and are interdependent in spermatocytes.

Conclusions:

• Drosophila tBRD-1 and tBRD-2 associate to form a functional BET complex in spermatocytes.
• This tBRD-1/tBRD-2 complex recapitulates the essential role of the mammalian BRDT protein in spermatogenesis.
• The findings reveal a conserved mechanism for BET protein function in male germ cell development across species.