Increasing evidence suggests that posttranscriptional regulation is a key player in the transition between mature pollen and the progamic phase (from pollination to fertilization). Nonetheless, the actors in this messenger RNA (mRNA)-based gene expression reprogramming are poorly understood. We demonstrate that the evolutionarily conserved RNA-binding protein LARP6C is necessary for the transition from dry pollen to pollen tubes and the guided growth of pollen tubes towards the ovule in Arabidopsis thaliana. In dry pollen, LARP6C binds to transcripts encoding proteins that function in lipid synthesis and homeostasis, vesicular trafficking, and polarized cell growth. LARP6C also forms cytoplasmic granules that contain the poly(A) binding protein and possibly represent storage sites for translationally silent mRNAs. In pollen tubes, the loss of LARP6C negatively affects the quantities and distribution of storage lipids, as well as vesicular trafficking. In Nicotiana benthamiana leaf cells and in planta, analysis of reporter mRNAs designed from the LARP6C target MGD2 provided evidence that LARP6C can shift from a repressor to an activator of translation when the pollen grain enters the progamic phase. We propose that LARP6C orchestrates the timely posttranscriptional regulation of a subset of mRNAs in pollen during the transition from the quiescent to active state and along the progamic phase to promote male fertilization in plants.

• MeSH
• 5' nepřekládaná oblast MeSH
• Arabidopsis cytologie   genetika   růst a vývoj   MeSH
• cytoplazmatická granula genetika   metabolismus   MeSH
• geneticky modifikované rostliny MeSH
• lipidy biosyntéza   genetika   MeSH
• messenger RNA genetika   metabolismus   MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• proteiny vázající RNA genetika   metabolismus   MeSH
• pylová láčka cytologie   genetika   růst a vývoj   MeSH
• regulace genové exprese u rostlin MeSH
• RNA rostlin metabolismus   MeSH
• tabák genetika   MeSH
• vazba proteinů MeSH
• vazebná místa MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 5' nepřekládaná oblast MeSH
• AT3G19090 protein, Arabidopsis MeSH Prohlížeč
• lipidy MeSH
• messenger RNA MeSH
• proteiny huseníčku MeSH
• proteiny vázající RNA MeSH
• RNA rostlin MeSH

The nucleolus is the site of rRNA gene transcription, rRNA processing, and ribosome biogenesis. However, the nucleolus also plays additional roles in the cell. We isolated nucleoli using fluorescence-activated cell sorting (FACS) and identified nucleolus-associated chromatin domains (NADs) by deep sequencing, comparing wild-type plants and null mutants for the nucleolar protein NUCLEOLIN 1 (NUC1). NADs are primarily genomic regions with heterochromatic signatures and include transposable elements (TEs), sub-telomeric regions, and mostly inactive protein-coding genes. However, NADs also include active rRNA genes and the entire short arm of chromosome 4 adjacent to them. In nuc1 null mutants, which alter rRNA gene expression and overall nucleolar structure, NADs are altered, telomere association with the nucleolus is decreased, and telomeres become shorter. Collectively, our studies reveal roles for NUC1 and the nucleolus in the spatial organization of chromosomes as well as telomere maintenance.

• Klíčová slova
• heterochromatin, nuclear architecture, nucleolus, nucleolus-associated chromatin domains, telomere,
• MeSH
• Arabidopsis MeSH
• buněčné jadérko metabolismus   MeSH
• exprese genu * MeSH
• fosfoproteiny metabolismus   MeSH
• genetická transkripce genetika   MeSH
• genom rostlinný * MeSH
• heterochromatin genetika   metabolismus   MeSH
• nukleolin MeSH
• proteiny vázající RNA metabolismus   MeSH
• ribozomální DNA genetika   MeSH
• RNA ribozomální metabolismus   MeSH
• telomery metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• fosfoproteiny MeSH
• heterochromatin MeSH
• proteiny vázající RNA MeSH
• ribozomální DNA MeSH
• RNA ribozomální MeSH