Biology subjects

Moore, A. J.

Publications and source records attributed to Moore, A. J..

7 recordsLinked to original sources

bioRxiv2018

Regulation of checkpoint kinase signalling and tumorigenesis by the NF-κB regulated gene, CLSPN

Inhibition of the tumour promoting activities of NF-{kappa}B by cell signalling pathways has been proposed as a natural mechanism to limit the development of cancer. However, there has been a lack of evidence for these effects in vivo. Here we report that RelAT505A mice, where a CHK1 targeted Thr505 phosphosite is mutated to alanine, display earlier onset of MYC driven lymphoma than wild type littermates. We describe a positive feedback loop in which the NF-{kappa}B subunits RelA and c-Rel, in a manner dependent upon RelA Thr505 phosphorylation, drive the expression of the ATR checkpoint kinase regulator Claspin in response to DNA replication stress in cancer cells. This in turn is required for maintenance of CHK1 activity. Loss of a single allele of the Clspn gene in mice is sufficient to drive earlier tumorigenesis and low levels of CLSPN mRNA expression are associated with worse survival in some forms of human cancer. We propose that loss of this pathway early in tumorigenesis promotes cancer development through increased genomic instability. However, in malignant cancer cells it can help promote their addiction to the checkpoint kinase signalling required for the maintenance of genomic integrity. Importantly, disruption of this pathway leads to resistance of cells to treatment with CHK1 inhibitors. Claspin expression could therefore act as a biomarker for responsiveness of patients to CHK1 inhibitors and provide a potential pathway for the development of tumour resistance.

cancer biology↗

bioRxiv2018

Gene-regulatory independent functions for insect DNA methylation

The function of cytosine (DNA) methylation in insects remains unknown. Here we provide evidence for the functional role of the maintenance DNA methyltransferase 1 (Dnmt1) in an insect using experimental manipulation. Through RNA interference (RNAi) we successfully post-transcriptionally knocked down Dnmt1 in ovarian tissue of the hemipteran Oncopeltus fasciatus (the large milkweed bug). Individuals depleted for Dnmt1, and subsequently DNA methylation, failed to reproduce. Eggs were inviable and declined in number, and nuclei structure of follicular epithelium was aberrant. Depletion of DNA methylation did not result in changes in gene or transposable element expression revealing an important function of DNA methylation seemingly not contingent on gene expression. Our work provides direct experimental evidence for a functional role of Dnmt1 and DNA methylation independent of gene expression in insects.

genetics↗

bioRxiv2017

Id proteins suppress E2A-driven innate-like T cell development prior to TCR selection

Id proteins have been shown to promote the differentiation of conventional {beta} and {gamma}{delta}T cells, and to suppress the expansion of invariant Natural Killer T (iNKT) cells and innate-like {gamma}{delta}NKT within their respective cell lineages. However, it remains to be determined whether Id proteins regulate lineage specification in developing T cells that give rise to these distinct cell fates. Here we report that in the absence of Id2 and Id3 proteins, E2A prematurely activates genes critical for the iNKT cell lineage prior to TCR expression. Enhanced iNKT development in Id3-deficient mice lacking {gamma}{delta} NKT cells suggests that Id3 regulates the lineage competition between these populations. RNA-Seq analysis establishes E2A as the transcriptional regulator of both iNKT and {gamma}{delta}NKT development. In the absence of pre-TCR signaling, Id2/Id3 deletion gives rise to a large population of iNKT cells and a unique innate-like DP population, despite the block in conventional {beta} T cell development. The transcriptional profile of these unique DP cells reflects enrichment of innate-like signature genes, including PLZF (Zbtb16) and Granzyme A (Gzma). Results from these genetic models and genome-wide analyses suggest that Id proteins suppress E2A-driven innate-like T cell programs prior to TCR selection to enforce predominance of conventional T cells.

immunology↗

bioRxiv2017

Early developmental morphology reflects independence from parents in social beetles

The variation in degree of offspring dependence in parents where parental care has evolved is striking, from feeding independence at birth to complete dependence on parents for all nutritional resources. This presents an evolutionary puzzle. Why lose the ability to feed as a contingency when parents may die or abandon broods? Comparisons of altricial and precocial vertebrates suggest that there may be life-history and developmental costs to early independence1-3. The generality of this beyond vertebrates is unclear, but we can extend the comparison as invertebrate species also vary in the level of independence in early life-history stages. For example, larvae of several burying beetle species (Nicrophorus), a genus in which parents regurgitate pre-digested food to begging larvae, have lost the ability to self-feed thus creating complete parental dependency for first instars4. Here, we ask whether variation in dependency amongst burying beetles is related to heterochrony in development of a more complex morphological structures. We show that the rate of development and allometry of mandibles of precocial larvae that can self-feed from birth are the same as those in altricial larvae that cannot survive without parenting. Instead, self-feeding is associated with shape variation in mandibles. In altricial species first instar larvae have smooth mandibles, whereas in precocial species mandibles are serrated. Later instars, which can self-feed in all species, have serrated mandibles. Serrations on teeth generally function to \"grip and rip\"5, whereas smooth blades function more to puncture6, and broods of altricial but not precocial Nicrophorus larvae show evidence for siblicide. We therefore suggest that altricial first-instar mandibles function more as weapons than feeding tools when released from self-feeding. This study presents a novel coevolution between developmental timing and parenting potentially mediated by sibling competition.

evolutionary biology↗

bioRxiv2017

Changes Of Gene Expression But Not Cytosine Methylation Are Associated With Behavioural Plasticity Of Parental Care

Behaviour is often on the front line of plasticity in response to different environments. At the genetic level, behavioural changes are likely to be associated with changes of gene expression. Most studies to date have focused on gene expression differences associated with discrete behavioural states reflecting development or age-related changes, such as honey bee castes. However, more rapidly flexible behaviour is often observed in response to social context or simple individual variation. The differences in genetic influences for the different forms of plasticity are poorly understood. In this study we contrasted gene expression during male parental care of the burying beetle, Nicrophorus vespilloides, in a factorial design. Male N. vespilloides males typically do not provide care when females are present. However, male care is inducible by the removing female and has parental effects equivalent to female care. We used this experimental manipulation to isolate gene expression and cytosine methylation associated with differences of behavioural state, differences of social context, or differences of individual flexibility for expressing care. The greatest number of differentially expressed genes was associated with behavioural state, followed by differences of social contexts, and lastly differences of individual variation. DNA methylation has been hypothesized to regulate the transcriptional architecture that regulates behavioural transitions. We tested this hypothesis by quantifying differences of cytosine methylation that were associated with differences of behavioural state and individual flexibility. Changes of cytosine methylation were not associated with changes of gene expression. Our results suggest a hierarchical association between gene expression and the different sources of variation that influence behaviour, but that this process is not controlled by DNA methylation despite reflecting levels of plasticity in behaviour. Our results further suggest that the extent that a behaviour is transient plays an underappreciated role in determining the molecular mechanisms that underpin the behaviour.

genetics↗

bioRxiv2017

Duplication And Sub/Neofunctionalization Of malvolio, An Insect Homolog Of Nramp, In The Subsocial Beetle Nicrophorus vespilloides

Gene duplication has long been thought to play a facilitating role in evolution. With growing numbers of sequenced genomes, increasing numbers of duplicate genes are uncovered with unknown functions. Here we examine malvolio, a gene involved in heavy metal transport but that also affects behavior in honey bees and Drosophila. There is only one copy of malvolio in honey bees and Drosophila despite its different roles. A phylogenetic analysis in insects suggests that malvolio has duplicated multiple times in different orders. To test if the two copies might have different functions, we examined expression levels of malvolio in brain, fat bodies, Malpighian tubules, midgut, ovaries, testes and thoracic musculature in the beetle Nicrophorus vespilloides. We found that mvl1 was expressed in all tissues, with highest expression in fat bodies and relatively lower expression in testes, Malpighian tubules, and brain, and ovaries. Expression of mvl2 differed, with significant expression only seen in brain and midgut. Because malvolio has been implicated in behavior, and these beetles have highly developed parenting behavior, we next examined expression during different behavioral states including virgin, mating, preparing resources for offspring, feeding offspring and post care. We found differing expression patterns for the two copies, with mvl1 increasing in expression during resource preparation and feeding offspring, and mvl2 decreasing in these same states. Given these patterns of expression, we suggest that malvolio in N. vespilloides has experienced sub/neofunctionalization following its duplication, and is evolving differing and tissue-specific roles in behavior and physiology.

evolutionary biology↗

bioRxiv2017

The transcriptional basis of quantitative behavioral variation

What causes individuals to produce quantitatively different phenotypes? While substantial research has focused on the allelic changes that affect phenotype, we know less about how gene expression accompanies variable phenotypes. Here, we investigate the transcriptional basis of variation in parental provisioning using two species of burying beetle, Nicrophorus orbicollis and Nicrophorus vespilloides. Specifically, we used RNA-seq to compare the transcriptomes of parents that provided high amounts of provisioning behavior versus low amounts in males and females of each species. We found that there were no overarching transcriptional patterns that distinguish high from low caring parents, and no informative transcripts that displayed particularly large expression differences in females or males. However, we did find more subtle gene expression changes between high and low provisioning parents that are consistent across sexes as well as between the two species. Furthermore, we show that transcripts previously implicated in transitioning into parental care in N. vespilloides had high variance in the levels of transcription and were unusually likely to display differential expression between high and low provisioning parents. Thus, quantitative behavioral variation appears to reflect many transcriptional differences of small effect. We show that nuanced regulation of the same gene products that are required for the transition of one behavioral state to another are also those influencing variation within a behavioral state.\n\nAuthor SummaryBurying beetles in the genus Nicrophorus breed on vertebrate carcasses and provide advanced parental care to their offspring by regurgitating partially digested flesh. However, all adult beetles do not uniformly express this trait. Some provide a large amount of parenting to their offspring, and some only a little. Here, we investigate the genetic causes of why some Nicrophorus beetles feed their offspring more than others. We demonstrate that this difference is likely caused by many small changes in gene expression, rather than a few genes that have major effects. We also find that some of the same genes that help to turn on parental care behavior in burying beetles also seem to play a role in determining how much care a beetle gives. These results provide new angles on longstanding questions about the complexity of the mechanisms that underlie quantitative variation in populations.

genetics↗