A cell-type-specific multi-protein complex regulates expression of Cyclin B protein inDrosophilamale meiotic prophase

Abstract

During meiosis, germ cell and stage-specific components impose additional layers of regulation on the core cell cycle machinery to set up an extended G2 period termed meiotic prophase. In Drosophila males, meiotic prophase lasts 3.5 days, during which spermatocytes turn up expression of over 3000 genes and grow 25-fold in volume. Previous work showed that the core cell cycle regulator Cyclin B (CycB) is subject to translational repression in immature Drosophila spermatocytes, mediated by the RNA-binding protein Rbp4 and its partner Fest. Here we show that another spermatocyte-specific protein, Lut, is required for translational repression of cycB in an 8-hour window just before spermatocytes are fully mature. In males mutant for rbp4 or lut, spermatocytes enter and exit the meiotic divisions 6-8 hours earlier than in wild-type. In addition, we show that spermatocyte-specific isoforms of Syncrip (Syp) are required for expression of CycB protein and normal entry into the meiotic divisions. Both Lut and Syp interact with Fest in an RNA-independent manner. Thus a complex of spermatocyte-specific regulators choreograph the timing of expression of CycB protein during male meiotic prophase.

A Developmental Mechanism to Regulate Alternative Polyadenylation in an Adult Stem Cell Lineage

“…For Immunoprecipita7on (IP) and co-IP experiments, testes were dissected into 1X PBS on a cyclops dissec7ng dish at room temperature from batches of 50 flies for a maximum of 30 minutes per batch, snap-frozen in liquid nitrogen and stored at -80 o C. For one sample ~100 pairs of testes were used. The day before the actual IP, 2 uL per sample of rabbit an7-HA an7bodies (Cell Signalling Technologies, #3724) were crosslinked to magne7c beads as described in Baker et al 2023. The day of the experiment, beads crosslinked with an7body were rinsed 1 7me in 200 mM glycine pH 2.5 and washed once for 5 minutes in 200 mM glycine pH 2.5 to remove noncrosslinked an7bodies, then blocked for 1 hour in 10% BSA in 50 mM Tris pH 8, and re-suspended in 20 uL of RIPA buffer and stored at 4 o C while cell lysate was prepared.…”