-
[
International Worm Meeting,
2007]
A lack of in vivo models has hampered insight into the mechanisms driving cell-invasive behavior. The behavior of a single uterine cell in Caenorhabditis elegans called the anchor cell (AC) provides such an in vivo model, allowing for easy visualization and genetic manipulation. During normal development in the C. elegans hermaphrodite, the AC invades through the underlying juxtaposed uterine and ventral epidermal basement membranes (BM) to establish the initial uterine-vulval contact. In addition to the genetic tractability and ease of visualization, the consistency of this event, occurring at the same time in every wild-type hermaphrodite, makes for a powerful model of cell invasion. We have established an in vivo system to visualize anchor cell invasion as it occurs in real time using a laminin-GFP fusion (LAM-1::GFP, Kao and Wadsworth 2006, Dev Biol. 290(1): 211-219) or a hemicentin-GFP fusion (GFP-hemicentin, Vogel and Hedgecock 2001, Development 128(6): 883-894), both markers of the BM, in combination with a PH::mCherry (PH domain from PLC?, a gift from Anjon Audhya) driven by an AC-specific promoter, labeling the invasive membrane (Sherwood et al. 2005, Cell 121(6): 951-962). To investigate the real-time dynamics of invasion, we have begun to characterize AC invasion in wild-type animals. Prior to invasion there is a deposition of GFP-hemicentin and an apparent increase of LAM-1::GFP in the uterine BM directly below the AC, suggesting that the AC deposits or recruits additional BM components, prior to migration through it. Invasion appears to initiate with a single filopod extending through a tiny hole in the BM. Once this filopodial process reaches through the BM, possibly contacting vulval cells below, it begins to widen, often fanning out on the ventral side of the BM. This widening of the AC extension seems to be coincident with widening of the hole in the BM, as visualized by LAM-1::GFP. The initial characterization of wild-type invasion has brought about several questions. 1) How is the initial filopod generated, and how does it penetrate through the BM? 2) What dictates the precise location of the initial protrusive filopod? 3) What happens to the BM under the AC as the filopod widens? 4) Do other BM components similarly increase under the AC, how are they recruited there, and what function does their increase serve? It is our hope that through a detailed cell-biological analysis, in combination with genetic screens and mutant analysis, that we will gain insight into these questions and lead to a better understanding of the mechanisms that endow invasive cells with the ability to traverse basement membranes.
-
[
Dev Comp Immunol,
2011]
Caenorhabditis elegans has become a useful model for studying innate immunity. ELT-2, which is homologous to human GATA-4, -5 and -6, is considered the primary GATA transcription factor controlling intestinal immunity in C. elegans. In this study, we characterize the timeline of intestinal distension in nematodes where ELT-2 and another intestinal GATA transcription factor, ELT-7, are abrogated by RNAi using two different models: colonization and toxin-based infections by Pseudomonas aeruginosa. We show that both ELT-2 and ELT-7 are important for survival of C. elegans exposed to P. aeruginosa. Intestinal distension is accelerated in
elt-2 RNAi nematodes, and is observed in colonization but not toxin-based Pseudomonas infection. Upon onset of intestinal distension, nematodes die within 24 h, regardless of experimental treatment. These data provide new insight into the role of ELT-2 and ELT-7 in protecting C. elegans against P. aeruginosa infection.
-
[
Curr Opin Chem Biol,
2014]
The site specific, co-translational introduction of unnatural amino acids into proteins produced in cells has been facilitated by the development of the pyrrolysyl-tRNA synthetase/tRNACUA pair. This pair can now be used to direct the site-specific incorporation of designer amino acids in E. coli, yeast, mammalian cells, and animals (the worm, C. elegans and the fly, D. melanogaster). Developments in encoding components of rapid bioorthogonal reactions are providing new opportunities for labelling and visualising proteins. A new method called stochastic orthogonal recoding of translation with chemoselective modification (SORT-M) leverages advances in genetic code expansion and bioorthogonal chemistry to label proteomes with diverse chemistry at diverse codons in E. coli, mammalian cells, and in spatially and temporally defined sets of cells in the fly. Proteomes in targeted sets of cells have been visualised by SORT-M and proteins in targeted cells have been identified by SORT-M.
-
[
Philos Trans R Soc Lond B Biol Sci,
2013]
CRYAB (B-crystallin) is expressed in many tissues and yet the R120G mutation in CRYAB causes tissue-specific pathologies, namely cardiomyopathy and cataract. Here, we present evidence to demonstrate that there is a specific functional interaction of CRYAB with desmin intermediate filaments that predisposes myocytes to disease caused by the R120G mutation. We use a variety of biochemical and biophysical techniques to show that plant, animal and ascidian small heat-shock proteins (sHSPs) can interact with intermediate filaments. Nevertheless, the mutation R120G in CRYAB does specifically change that interaction when compared with equivalent substitutions in HSP27 (R140G) and into the Caenorhabditis elegans HSP16.2 (R95G). By transient transfection, we show that R120G CRYAB specifically promotes intermediate filament aggregation in MCF7 cells. The transient transfection of R120G CRYAB alone has no significant effect upon cell viability, although bundling of the endogenous intermediate filament network occurs and the mitochondria are concentrated into the perinuclear region. The combination of R120G CRYAB co-transfected with wild-type desmin, however, causes a significant reduction in cell viability. Therefore, we suggest that while there is an innate ability of sHSPs to interact with and to bind to intermediate filaments, it is the specific combination of desmin and CRYAB that compromises cell viability and this is potentially the key to the muscle pathology caused by the R120G CRYAB.
-
Elliott A, Taylor M, Mwaka AD, Anguzu R, Ogwang R, Newton C, Vincent A, Idro R, Akun P, Opar B, Marsh K, Abbo C, Nakamya P
[
BMC Neurol,
2019]
BACKGROUND: Nodding syndrome is a poorly understood neurological disorder of unknown aetiology, affecting several thousand children in Africa. There has been a consistent epidemiological association with infection by the filarial parasite, Onchocerca volvulus and antibodies to leiomodin and DJ-1, cross-reacting with O.volvulus proteins, have been reported. We hypothesized that nodding syndrome is a neuro-inflammatory disorder, induced by antibodies to O.volvulus or its symbiont, Wolbachia, cross-reacting with human neuron proteins and that doxycycline, which kills Onchocerca through effects on Wolbachia, may be used as treatment. METHODS: This will be a two-arm, double-blind, placebo-controlled, randomised phase II trial of doxycycline 100mg daily for six weeks in 230 participants. Participants will be patients' ages8years with nodding syndrome. They will receive standard of care supportive treatment. All will be hospitalised for 1-2weeks during which time baseline measurements including clinical assessments, EEG, cognitive and laboratory testing will be performed and antiepileptic drug doses rationalised. Participants will then be randomised to either oral doxycycline (Azudox, Kampala Pharmaceutical Industries) 100mg daily or placebo. Treatment will be initiated in hospital and continued at home. Participants will be visited at home at 2, 4 and 6weeks for adherence monitoring. Study outcomes will be assessed at 6, 12, 18 and 24-month visits. Analysis will be by intention to treat. The primary efficacy outcome measure will be the proportion of patients testing positive and the levels or titires of antibodies to host neuron proteins (HNPs) and/or leiomodin at 24months. Secondary outcome measures will include effect of the intervention on seizure control, inflammatory markers, cognitive function, disease severity and quality of life. DISCUSSION: This trial postulates that targeting O.volvulus through drugs which kill Wolbachia can modify the pathogenic processes in nodding syndrome and improve outcomes. Findings from this study are expected to substantially improve the understanding and treatment of nodding syndrome. TRIAL REGISTRATION: Registered with clinicaltrials.gov ID: NCT02850913 on 1st August, 2016.
-
Pennington PR, Heistad RM, Nyarko JNK, Barnes JR, Bolanos MAC, Parsons MP, Knudsen KJ, De Carvalho CE, Leary SC, Mousseau DD, Buttigieg J, Maley JM, Quartey MO
[
Sci Rep,
2021]
The pool of -Amyloid (A) length variants detected in preclinical and clinical Alzheimer disease (AD) samples suggests a diversity of roles for A peptides. We examined how a naturally occurring variant, e.g. A(1-38), interacts with the AD-related variant, A(1-42), and the predominant physiological variant, A(1-40). Atomic force microscopy, Thioflavin T fluorescence, circular dichroism, dynamic light scattering, and surface plasmon resonance reveal that A(1-38) interacts differently with A(1-40) and A(1-42) and, in general, A(1-38) interferes with the conversion of A(1-42) to a -sheet-rich aggregate. Functionally, A(1-38) reverses the negative impact of A(1-42) on long-term potentiation in acute hippocampal slices and on membrane conductance in primary neurons, and mitigates an A(1-42) phenotype in Caenorhabditis elegans. A(1-38) also reverses any loss of MTT conversion induced by A(1-40) and A(1-42) in HT-22 hippocampal neurons and APOE 4-positive human fibroblasts, although the combination of A(1-38) and A(1-42) inhibits MTT conversion in APOE 4-negative fibroblasts. A greater ratio of soluble A(1-42)/A(1-38) [and A(1-42)/A(1-40)] in autopsied brain extracts correlates with an earlier age-at-death in males (but not females) with a diagnosis of AD. These results suggest that A(1-38) is capable of physically counteracting, potentially in a sex-dependent manner, the neuropathological effects of the AD-relevant A(1-42).
-
[
Worm Breeder's Gazette,
2003]
Wormgenes is a new resource for C.elegans offering a detailed summary about each gene and a powerful query system.
-
[
Front Pharmacol,
2020]
Oligomeric assembly of Amyloid- (A) is the main toxic species that contribute to early cognitive impairment in Alzheimer's patients. Therefore, drugs that reduce the formation of A oligomers could halt the disease progression. In this study, by using transgenic <i>Caenorhabditis elegans</i> model of Alzheimer's disease, we investigated the effects of frondoside A, a well-known sea cucumber <i>Cucumaria frondosa</i> saponin with anti-cancer activity, on A aggregation and proteotoxicity. The results showed that frondoside A at a low concentration of 1 M significantly delayed the worm paralysis caused by A aggregation as compared with control group. In addition, the number of A plaque deposits in transgenic worm tissues was significantly decreased. Frondoside A was more effective in these activities than ginsenoside-Rg3, a comparable ginseng saponin. Immunoblot analysis revealed that the level of small oligomers as well as various high molecular weights of A species in the transgenic <i>C. elegans</i> were significantly reduced upon treatment with frondoside A, whereas the level of A monomers was not altered. This suggested that frondoside A may primarily reduce the level of small oligomeric forms, the most toxic species of A. Frondoside A also protected the worms from oxidative stress and rescued chemotaxis dysfunction in a transgenic strain whose neurons express A. Taken together, these data suggested that low dose of frondoside A could protect against A-induced toxicity by primarily suppressing the formation of A oligomers. Thus, the molecular mechanism of how frondoside A exerts its anti-A aggregation should be studied and elucidated in the future.
-
[
International Journal of Developmental Biology,
1998]
Pleiotropy , a situation in which a single gene influences multiple phenotypic tra its, can arise in a variety of ways. This paper discusses possible underlying mechanisms and proposes a classification of the various phenomena involved.
-
[
Curr Biol,
2011]
Recent work on a Caenorhabditis elegans transmembrane ATPase reveals a central role for the aminophospholipid phosphatidylethanolamine in the production of a class of extracellular vesicles.