Biology subjects

Agapiou, M.

Publications and source records attributed to Agapiou, M..

3 recordsLinked to original sources

bioRxiv2024

Translational activity of 80S monosomes varies dramatically across different tissues

SummaryTranslational regulation at the stage of initiation can impact the number of ribosomes translating each mRNA molecule. However, the translational activity of single 80S ribosomes (monosomes) on mRNA is less well understood, even though these 80S monosomes represent the dominant ribosomal complexes in vivo. Here, we used cryo-EM to determine the translational activity of 80S monosomes across different tissues in Drosophila melanogaster. We discovered that while head and embryo 80S monosomes are highly translationally active, testis and ovary 80S monosomes are translationally inactive. RNA-Seq analysis of head monosome- and polysome-translated mRNAs, revealed that head 80S monosomes preferentially translate mRNAs with TOP motifs, short 5-UTRs, short ORFs and are enriched for uORFs. Overall, these findings highlight that regulation of translation initiation, and that protein synthesis is mostly performed by monosomes in head and embryo, whilst polysomes are the main source of protein production in testis and ovary. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=87 SRC="FIGDIR/small/600330v1_ufig1.gif" ALT="Figure 1"> View larger version (21K): org.highwire.dtl.DTLVardef@12881e5org.highwire.dtl.DTLVardef@6804dborg.highwire.dtl.DTLVardef@116fa63org.highwire.dtl.DTLVardef@19095d6_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LID. melanogaster 80S monosomes and polysomes purified from different tissues exhibit different translational activities C_LIO_LIHead and 0-2 hr embryo 80S monosomes are highly translationally active C_LIO_LITestis and ovary 80S monosomes are translationally inactive C_LIO_LIHead 80S monosomes preferentially translate mRNAs with TOP motifs, short 5-UTRs, short ORFs and are enriched for uORFs C_LIO_LIHead polysomes preferentially translate mRNAs with neuronal functions C_LI

molecular biology↗

bioRxiv2022

Held out wings RNA binding activity in the cytoplasm during early spermatogenesis

Held out wings (HOW) is an RNA-binding protein essential for spermatogenesis in Drosophila melanogaster. HOW is a signal transduction and activation of RNA (STAR) protein, regulating post-transcriptional gene expression. The characteristics of RNA-binding by the conserved short cytoplasmic isoform, HOW(S), are unknown. In vivo RIP-seq identified 121 novel transcripts bound by HOW(S) in germ stem cells and spermatogonia, many with signal transduction functions. (A/G/U)CUAAC motifs were enriched in 3-UTRs and GCG(A/U)G in 5-UTRs. HOW binds with high-affinity to sites containing CUAAC motifs from lola and hipk mRNAs. This study provides new insight into STAR protein-RNA interactions and functions in spermatogenesis.

molecular biology↗

bioRxiv2020

Specialisation of ribosomes in gonads through paralog-switching

Ribosomes have long been thought of as homogeneous macromolecular machines, but recent evidence suggests they are heterogeneous and could be specialised to regulate translation. Here, we have characterised ribosomal protein heterogeneity across 4 tissues of Drosophila melanogaster. We find that testes and ovaries contain the most heterogeneous ribosome populations, which occurs through a combination of paralog-enrichment and paralog-switching. We have solved structures of ribosomes purified from in vivo tissues by cryo-EM, revealing differences in precise ribosomal arrangement for testis and ovary 80S ribosomes. Differences in the amino acid composition of paralog pairs and their localisation on the ribosome exterior indicate paralog-switching could alter the ribosome surface, enabling different proteins to regulate translation. One testis-specific paralog-switching pair is also found in humans, suggesting this is a conserved site of ribosome heterogeneity. Overall, this work allows us to propose that mRNA translation might be regulated in the gonads through ribosome heterogeneity, providing a potential means of ribosome specialisation.

biochemistry↗