Přehled o publikaci

Regulation of gene expression often involves RNP granules, dynamic structures formed by multivalent protein-nucleic acid interactions that exhibit properties of liquid-liquid phase condensates. We have uncovered an important role for RNP granules in the regulation of meiotic genes in Arabidopsis. Meiosis generates haploid spores from diploid progenitors, and the meiotic mode of chromosome segregation is imposed by the expression of specialized genes. Thus, entry as well as exit form meiosis are accompanied by extensive remodeling of the cell division machinery. We have previously discovered a mechanism that terminates the meiotic program by inhibiting translation through sequestering the translation initiation factor eIF4F in P-bodies (Cairo et al. 2022). Here, I will present unpublished findings that further highlight the regulation of meiotic genes by specialized RNP granules. Meiosis can last several days and most of the time the chromatin is in a highly condensed state, suggesting limited transcription, which is supported by the observation that major changes in the transcriptome occur at the onset of meiosis. This raises the question of how late meiotic genes are regulated. Through a genetic screen aimed at identifying genes that control meiotic progression, we uncovered a zinc finger-containing protein, CDM1. CDM1 forms prominent and highly dynamic cytoplasmic speckles in early meiosis that associate with P-bodies. Curiously, CDM1 inactivation only leads to defects in late meiosis, namely cytokinesis and microspore formation. We hypothesized that CDM1 is an RNA binding protein that sequesters late meiotic transcripts synthesized early in meiosis in RNP granules and releases them for expression at the end of meiosis. RIP-seq analysis on Arabidopsis meiocytes identified putative targets of CDM1 regulation, at least one of which has so far been validated by analysis of its expression through meiosis using a YFP reporter line. Experiments including smRNA-FISH and in vitro RNA binding assays are underway to confirm that the candidate gene is a bona fide target of CDM1 regulation