Biology subjects

Weiss, R. S.

Publications and source records attributed to Weiss, R. S..

5 recordsLinked to original sources

bioRxiv2022

ATM modulates nuclear mechanics by regulating lamin A levels

Ataxia-telangiectasia mutated (ATM) is one of the three main apical kinases at the crux of DNA damage response and repair in mammalian cells. ATM activates a cascade of downstream effector proteins to regulate DNA repair and cell cycle checkpoints in response to DNA double-strand breaks. While ATM is predominantly known for its role in DNA damage response and repair, new roles of ATM have recently begun to emerge, such as in regulating oxidative stress or metabolic pathways. Here, we report the surprising discovery that ATM inhibition and deletion lead to reduced expression of the nuclear envelope protein lamin A. Lamins are nuclear intermediate filaments that modulate nuclear shape, structure, and stiffness. Accordingly, inhibition or deletion of ATM resulted in increased nuclear deformability and enhanced cell migration through confined spaces, which requires substantial nuclear deformation. These findings point to a novel connection between ATM and lamin A and may have broad implications for cells with ATM mutations--as found in patients suffering from Ataxia Telangiectasia and many human cancers--which could lead to enhanced cell migration and increased metastatic potential.

cell biology↗

bioRxiv2021

Sequencing Micronuclei Reveals the Landscape of Chromosomal Instability

Genome instability (GIN) is a main contributing factor to congenital and somatic diseases, but its sporadic occurrence in individual cell cycles makes it difficult to study mechanistically. One profound manifestation of GIN is the formation of micronuclei (MN), the engulfment of chromosomes or chromosome fragments in their own nuclear structures separate from the main nucleus. Here, we developed MN-seq, an approach for sequencing the DNA contained within micronuclei. We applied MN-seq to mice with mutations in Mcm4 and Rad9a, which disrupt DNA replication, repair, and damage responses. Data analysis and simulations show that centromere presence, fragment length, and a heterogenous landscape of chromosomal fragility all contribute to the patterns of DNA present within MN. In particular, we show that long genes, but also gene-poor regions, are associated with chromosome breaks that lead to the enrichment of particular genomic sequences in MN, in a genetic background-specific manner. Finally, we introduce single-cell micronucleus sequencing (scMN-seq), an approach to sequence the DNA present in MN of individual cells. Together, sequencing micronuclei provides a systematic approach for studying GIN and reveals novel molecular associations with chromosome breakage and segregation.

genomics↗

bioRxiv2021

Phosphoproteomics of ATR Signaling in Prophase I of Mouse Meiosis

During mammalian meiosis, the ATR kinase plays crucial roles in the coordination of DNA repair, meiotic sex chromosome inactivation and checkpoint signaling. Despite the importance of ATR in meiosis, the meiotic ATR signaling network remains largely unknown. Here we defined ATR signaling during prophase I in mice. Quantitative analysis of phosphoproteomes obtained after genetic ablation of the ATR-activating 9-1-1 complex or chemical inhibition of ATR revealed over 12,000 phosphorylation sites, of which 863 phosphorylation sites were dependent on both 9-1-1 and ATR. ATR and 9-1-1-dependent signaling was enriched for S/T-Q and S/T-X-X-K motifs and included proteins involved in DNA damage signaling, DNA repair, and piRNA and mRNA metabolism. We find that ATR targets the RNA processing factors SETX and RANBP3 and regulate their localization to the sex body. Overall, our analysis establishes a comprehensive map of ATR signaling in spermatocytes and highlights potential meiotic-specific actions of ATR during prophase I.

developmental biology↗

bioRxiv2021

Multiple 9-1-1 complexes promote homolog synapsis, DSB repair, and ATR signaling during mammalian meiosis

DNA damage response mechanisms have meiotic roles that ensure successful gamete formation. While completion of meiotic double-strand break (DSB) repair requires the canonical RAD9A-RAD1-HUS1 (9A-1-1) complex, mammalian meiocytes also express RAD9A and HUS1 paralogs, RAD9B and HUS1B, predicted to form alternative 9-1-1 complexes. The RAD1 subunit is shared by all predicted 9-1-1 complexes and localizes to meiotic chromosomes even in the absence of HUS1 and RAD9A. Here we report that testis-specific RAD1 disruption resulted in impaired DSB repair, germ cell depletion and infertility. Unlike Hus1 or Rad9a disruption, Rad1 loss also caused defects in homolog synapsis, ATR signaling and meiotic sex chromosome inactivation. Comprehensive testis phosphoproteomics revealed that RAD1 and ATR coordinately regulate numerous proteins involved in DSB repair, meiotic silencing, synaptonemal complex formation, and cohesion. Together, these results establish critical roles for both canonical and alternative 9-1-1 complexes in meiotic ATR activation and successful prophase I completion.

genetics↗

bioRxiv2021

IGF2BP2 Promotes Cancer Progression by Degrading the RNA Transcript Encoding a v-ATPase Subunit

Insulin-like growth factor 2 mRNA binding protein 2 (IGF2BP2) binds to various RNA transcripts and promotes cancer progression, although little is known regarding its regulation. Here we show IGF2BP2 is a substrate of the deacetylase and tumor suppressor sirtuin 1 (SIRT1) and regulates the expression of the vacuolar ATPase subunit ATP6V1A. SIRT1 down-regulation in aggressive cancers leads to increased acetylation of IGF2BP2 which recruits the XRN2 nuclease to degrade the ATP6V1A transcript, decreasing its expression. This impairs lysosomal function and results in the production of a secretome that enhances cancer cell proliferation and metastasis. These findings describe a previously unrecognized role for IGF2BP2 in the degradation of an mRNA transcript essential for lysosomal function and highlight how its sirtuin-regulated acetylation state can have significant biological and disease consequences. One Sentence SummaryAcetylation of the RNA binding protein IGF2BP2, upon down-regulation of SIRT1, leads to degradation of the transcript encoding ATP6V1A and impaired lysosomal function in aggressive cancer cells.

cell biology↗