Woollard AC et al. (2000) Genes Dev "The caenorhabditis elegans fate-determining gene mab-9 encodes a T-box protein required to pattern the posterior hindgut."

Woollard AC, Hodgkin JA

[Genes Dev, 2000]

Caenorhabditis elegans mab-9 mutants are defective in hindgut and male tail development because of cell fate transformations in two posterior blast cells, B and F. We have cloned mab-9 and show that it encodes a member of the T-box family of transcriptional regulators. MAB-9 localizes to the nucleus of B and F and their descendents during development, suggesting that it acts cell autonomously in the posterior hindgut to direct cell fate. T-box genes related to brachyury have also been implicated in hindgut patterning, and our results support models for an evolutionarily ancient role for these genes in hindgut formation.

Woollard AC et al. (1999) Mech Dev "Stu-7/air-2 is a C. elegans aurora homologue essential for chromosome segregation during embryonic and post-embryonic development."

Hodgkin JA, Woollard AC

[Mech Dev, 1999]

We have isolated a new sterile uncoordinated C. elegans mutant, stu-7, which is defective in post-embryonic cell divisions in a regionally-specific fashion. The anterior of the worm is relatively unaffected whereas the mid-body and/or posterior are markedly thin, often resulting in worms having a central 'waist'. We have cloned stu-7 and found that it encodes a member of the recently expanding aurora sub-family of serine/threonine kinases. Elimination of maternal as well as zygotic stu-7 expression reveals that stu-7 is essential for mitosis from the first embryonic cell cycle onwards and is required for chromosome segregation though not for centrosome separation or for setting up a bipolar spindle. Multicopy expression of stu-7 also causes mitotic defects, suggesting that the level of this protein must be tightly controlled in order to maintain genetic stability during development.

Hughes S et al. (2017) Adv Exp Med Biol "RUNX in Invertebrates."

Hughes S, Woollard A

[Adv Exp Med Biol, 2017]

Runx genes have been identified in all metazoans and considerable conservation of function observed across a wide range of phyla. Thus, insight gained from studying simple model organisms is invaluable in understanding RUNX biology in higher animals. Consequently, this chapter will focus on the Runx genes in the diploblasts, which includes sea anemones and sponges, as well as the lower triploblasts, including the sea urchin, nematode, planaria and insect. Due to the high degree of functional redundancy amongst vertebrate Runx genes, simpler model organisms with a solo Runx gene, like C. elegans, are invaluable systems in which to probe the molecular basis of RUNX function within a whole organism. Additionally, comparative analyses of Runx sequence and function allows for the development of novel evolutionary insights. Strikingly, recent data has emerged that reveals the presence of a Runx gene in a protist, demonstrating even more widespread occurrence of Runx genes than was previously thought. This review will summarize recent progress in using invertebrate organisms to investigate RUNX function during development and regeneration, highlighting emerging unifying themes.

Nimmo R et al. (2002) Bioessays "Widespread organisation of C. elegans genes into operons: fact or function?"

Woollard A, Nimmo R

[Bioessays, 2002]

A recent report by Blumenthal et al.((1)) provides convincing evidence that at least 15% of Caenorhabditis elegans genes are co-transcribed within over a thousand operons. Polycistronic transcription of gene clusters is very rare in eukaryotes. The widespread occurrence of operons in C. elegans thus raises some interesting questions about the origin and function of these multigenic transcriptional-units.

Brabin C et al. (2012) Worm "Finding a niche for seam cells?"

Brabin C, Woollard A

[Worm, 2012]

The C. elegans neuroectodermal seam cells provide a tractable and well-established model for studying the stem cell mode of division, due to the reiterative asymmetric divisions occurring during larval development. They are, however, not generally considered to be 'true' stem cells, owing to their eventual terminal differentiation and the lack of a defined stem cell niche-a microenvironment that promotes the proliferation and prevents the differentiation of the stem cells that reside within. Here, we discuss the concept of the niche in relation to the seam, with reference to our recent findings suggesting that the stem-like properties of the seam cells are maintained at least in part through protection from differentiation signals emanating from the surrounding hypodermal syncytium. Determining the applicability of the niche concept will require definition of these signals and will have important implications for the status of seam cells in the context of stem cell biology.

Ding SS et al. (2017) Sci Rep "Non-muscle myosin II is required for correct fate specification in the Caenorhabditis elegans seam cell divisions."

Woollard A, Ding SS

[Sci Rep, 2017]

During development, cell division often generates two daughters with different developmental fates. Distinct daughter identities can result from the physical polarity and size asymmetry itself, as well as the subsequent activation of distinct fate programmes in each daughter. Asymmetric divisions are a feature of the C. elegans seam lineage, in which a series of post-embryonic, stem-like asymmetric divisions give rise to an anterior daughter that differentiates and a posterior daughter that continues to divide. Here we have investigated the role of non-muscle myosin II (nmy-2) in these asymmetric divisions. We show that nmy-2 does not appear to be involved in generating physical division asymmetry, but nonetheless is important for specifying differential cell fate. While cell polarity appears normal, and chromosome and furrow positioning remains unchanged when nmy-2 is inactivated, seam cell loss occurs through inappropriate terminal differentiation of posterior daughters. This reveals a role for nmy-2 in cell fate determination not obviously linked to the primary polarity determination mechanisms it has been previously associated with.

Newbury S et al. (2004) RNA "The 5'-3' exoribonuclease xrn-1 is essential for ventral epithelial enclosure during C. elegans embryogenesis."

Woollard A, Newbury S

[RNA, 2004]

Ribonucleases have been studied in yeast and bacteria, but their biological significance to multicellular organisms is virtually unknown. However, there is increasing evidence that specific, timed transcript degradation is critical for regulation of many cellular processes, including early development and RNA interference. in this report we have investigated the effects of the 5'-3' exoribonuclease xrn-1 on the development of the nematode worm Caenorhabditis elegans. Silencing of xrn-1 expression using RNA interference results in embryos that fail to complete ventral enclosure, where the outer layer of cells normally closes over the mesoderm in a purse-string movement. Our data suggest that xrn-1 is involved in a critical aspect of epithelial movement and reveal an unexpected link between RNA stability and morphogenesis. Because xrn-1 is highly conserved in all eukaryotes, it is possible that it plays a role in similar morphological processes such as dorsal or thorax closure in Drosophila and wound healing in humans. In contrast to work in human tissue culture cells, where the 3'-5' pathway has been shown to be the most important for degradation of mRNAs. Our work shows that the 5'-3' degradation pathway is crucially important at a critical stage of development in C elegans. We have also investigated whether xrn-1 can influence the response of C. elegans to RNA interference. Our data indicate that xrn-1 plays a facilitating, but not crucial role in this process.

Xiong H et al. (2017) Sci Rep "An enhanced C. elegans based platform for toxicity assessment."

Woollard A, Xiong H, Pears C

[Sci Rep, 2017]

There is a well-defined regulatory framework governing the approval of chemicals for use as pharmaceuticals or release into the environment. Toxicity assessment is thus a major hurdle in the compound discovery pipeline, currently involving large scale animal testing. The search for alternative testing platforms is therefore an important priority. We have developed a convenient, low cost assay utilising the nematode Caenorhabditis elegans, to rapidly assess both acute toxicity and developmental and reproductive toxicity (DART). However the worm is protected by a robust cuticle that forms a barrier to chemical uptake. We assessed mutants with altered cuticle properties to identify sensitized strains optimized for toxicity assays. Evaluating the trade-off between increased permeability and reduced fitness identifies bus-5(br19) as the most suitable strain for chemical exposure. We demonstrate the applicability of this assay for a range of chemicals with differing properties, including a modified exposure protocol for volatile or less soluble compounds. This work enhances the effectiveness of C. elegans for convenient toxicity assessment, which could contribute to a reduction in the use of vertebrates particularly at the crucial early stages of product development. Strains identified in this work will also enhance the sensitivity of C. elegans based drug discovery platforms.

Nimmo R et al. (2005) Development "mab-2 encodes RNT-1, a C. elegans Runx homologue essential for controlling cell proliferation in a stem cell-like developmental lineage."

Woollard A, Nimmo R, Antebi A

[Development, 2005]

In this report, we demonstrate that C. elegans mab-2 mutants have defects in the development of a male-specific sense organ because of a failure in the proliferation of the stem cell-like lateral hypodermal (seam) cells. We show, by positional cloning, that mab-2 encodes RNT-1, the only C. elegans member of the Runx family of transcriptional regulators, which are postulated to act both as oncogenes and tumour suppressors in mammalian cells. Importantly, we find that rnt-1 is a rate-limiting regulator of seam cell proliferation in C. elegans, as overexpression of rnt-1 at particular developmental stages is capable of driving extra cell divisions, leading to seam cell hyperplasia. Loss of rnt-1 is correlated with upregulation of cki-1, a CDK inhibitor. Deregulated expression of Runx genes in humans is associated with various cancers, particularly leukaemias, suggesting a conserved role for Runx genes in controlling cell proliferation during development, especially in stem cell lineages. C. elegans is therefore an important model system for studying the biology, and oncogenic potential, of Runx genes.

Brabin C et al. (2011) PLoS Genet "The Caenorhabditis elegans GATA factor ELT-1 works through the cell proliferation regulator BRO-1 and the Fusogen EFF-1 to maintain the seam stem-like fate."

Appleford PJ, Woollard A, Brabin C

[PLoS Genet, 2011]

Seam cells in Caenorhabditis elegans provide a paradigm for the stem cell mode of division, with the ability to both self-renew and produce daughters that differentiate. The transcription factor RNT-1 and its DNA binding partner BRO-1 (homologues of the mammalian cancer-associated stem cell regulators RUNX and CBF, respectively) are known rate-limiting regulators of seam cell proliferation. Here, we show, using a combination of comparative genomics and DNA binding assays, that bro-1 expression is directly regulated by the GATA factor ELT-1. elt-1(RNAi) animals display similar seam cell lineage defects to bro-1 mutants, but have an additional phenotype in which seam cells lose their stem cell-like properties and differentiate inappropriately by fusing with the hyp7 epidermal syncytium. This phenotype is dependent on the fusogen EFF-1, which we show is repressed by ELT-1 in seam cells. Overall, our data suggest that ELT-1 has dual roles in the stem-like seam cells, acting both to promote proliferation and prevent differentiation.