Wani, Khursheed A. et al. (2009) International Worm Meeting "Genetic analysis of dopamine signaling in C. elegans."

Wani, Khursheed A., Chase, Daniel L.

[International Worm Meeting, 2009]

Dopamine acts through G protein-coupled receptors to modulate neural activity in the brain. Defects in dopamine signaling underlie neurological disorders including Parkinson''s disease, schizophrenia and drug addiction. Despite its clinical relevance, detailed understanding of how dopamine exerts its functions remains largely unknown. To identify the molecular mechanisms of dopamine signaling, we have taken a genetic approach using C. elegans as a model system. In C. elegans, dopamine acts through the D2-like receptor DOP-3 and the G-alpha (Ga) protein GOA-1 to inhibit locomotion in response to environmental cues. This inhibition of locomotion behavior is also observed when animals are exposed to exogenous dopamine with high concentrations causing paralysis. The paralytic effect of exogenous dopamine also acts through the DOP-3 receptor and allows us to perform robust genetic screens to identify novel components of dopamine signaling. Interestingly, null mutants lacking the DOP-3 receptor are partially resistant to paralysis, while null mutations in the Ga protein (GOA-1) coupled to this receptor cause complete resistance to exogenous dopamine. This suggests that there is another dopamine receptor in C. elegans coupled to GOA-1 that acts to inhibit locomotion. In order to identify this unknown receptor and its downstream effectors, we conducted an enhancer screen in which we mutagenized the dop-3 receptor mutant and identified second-site mutations that cause complete resistance to the paralytic effects of exogenous dopamine (similar to that observed in goa-1 null mutants). We screened 92,000 mutagenized haploid genomes and isolated 16 mutants. Mapping of these mutants using single-nucleotide polymorphisms followed by complementation analysis resulted in the identification of one previously-known dopamine signaling component as well as seven novel genes involved in dopamine response. We are characterizing these novel genes at the genetic, behavioral and molecular levels.

Wani, Khursheed A. et al. (2015) International Worm Meeting "Elucidating the role of interneuron RIM in the regulation of C. elegans locomotion."

Wani, Khursheed A., Li, Zhaoyu, Xu, Shawn, Piggott, Beverly J.

[International Worm Meeting, 2015]

Locomotion is a predominant motor program in C. elegans. During locomotion, C. elegans usually moves forward that is periodically interrupted by brief reversals. The neurons that control forward and backward locomotion are well characterized. The command interneuron, AVB, is known to drive forward locomotion, and AVA, AVD, and AVE command interneurons control backward locomotion. Another interneuron, RIM, sits at a unique position in the locomotion circuitry by forming connections with both forward and backward command interneurons. Interestingly, we found that both activation and inhibition of RIM promote backward locomotion. Further, RIM regulates reversals in a command interneuron-dependent, as well as independent manner. How could RIM have two opposite effects on the same behavioral response? To address this question, we are testing several models, hoping to identify the underlying circuit as well as synaptic and molecular mechanisms.

Wani, Khursheed A. et al. (2021) International Worm Meeting "NHR-49/PPAR-alpha and HLH-30/TFEB cooperate for C. elegans host defense via a flavin-containing monooxygenase"

Goswamy, Debanjan, Irazoqui, Javier E., Wani, Khursheed A., Ratnappan, Ramesh, Ghazi, Arjumand, Taubert, Stefan

[International Worm Meeting, 2021]

During bacterial infection, the host is confronted with multiple overlapping signals that are integrated at the organismal level to produce defensive host responses. How multiple infection signals are sensed by the host and how they elicit the transcription of host defense genes is much less understood at the whole-animal level than at the cellular level. The model organism Caenorhabditis elegans is known to mount transcriptional defense responses against intestinal bacterial infections that elicit overlapping starvation and infection responses, but the regulation of such responses is not well understood. Direct comparison of C. elegans that were starved or infected with Gram-positive pathogen Staphylococcus aureus revealed a large infection-specific transcriptional signature. Both the starvation response and the infection-specific signature were largely dependent on the transcription factor, HLH-30/TFEB, highlighting its key role as a transcriptional integrator of organismal stress during infection. Interestingly, we identified six genes that were specifically induced during infection even in the absence of HLH-30/TFEB, potentially revealing an alternative transcriptional host response signaling pathway. The induction of two of the six genes, fmo-2/FMO5 (encodes flavin-containing monooxygenase 2) and K08C7.4 (an uncharacterized gene), was entirely dependent on nuclear hormone receptor, NHR-49/PPAR-alpha. NHR-49/PPAR-alpha was required non cell-autonomously for fmo-2/FMO5 induction and host defense against S. aureus. Moreover, functional characterization of FMO-2/FMO5 suggested that its enzymatic activity is specifically required for host defense against S. aureus, revealing that FMO-2/FMO5 is a key host defense effector. Further, fmo-2/FMO5 was specifically induced by Gram-positive pathogens and Gram-positive natural microbiota of C. elegans. These findings for the first time reveal an infection-specific host response to S. aureus, identify HLH-30/TFEB as its main regulator, reveal that FMOs are important innate immunity effectors in animals, and identify the mechanism of FMO regulation through NHR-49/PPAR-alpha in C. elegans, with important implications for innate host defense in higher organisms.

Khursheed Wani et al. (2008) C.elegans Neuronal Development Meeting "Genetic Analysis of Dopamine Signaling in C. elegans"

Daniel Chase, Khursheed Wani

[C.elegans Neuronal Development Meeting, 2008]

Dopamine is a major neurotransmitter in the brain. Defects in dopamine signaling underlie neurological disorders including Parkinson''s disease, schizophrenia and drug addiction. Despite such clinical importance, our understanding of dopamine signaling and its regulation of neural activities are meager. Dopamine also controls neural activity in C. elegans. Endogenous dopamine acts on the motor circuit of C. elegans to inhibit locomotion in response to food [1]. Exogenous dopamine also inhibits locomotion and high concentrations cause paralysis [2]. Screens for mutants resistant to the paralytic effects of exogenous dopamine identified several dopamine-signaling components including the receptor DOP-3 and the G-alpha protein GOA-1 [3]. While goa-1 null mutants are completely resistant to exogenous dopamine, dop-3 null mutants are only partially resistant, suggesting that: 1) there are at least two receptors that bind dopamine to inhibit locomotion; and 2) these dopamine receptors are each coupled to GOA-1. To identify additional components of endogenous dopamine signaling pathways, we conducted a dop-3 enhancer screen. A total of 92,000 mutagenized haploid genomes were screened and 15 mutants were isolated that, like goa-1 mutants, were completely resistant to exogenous dopamine. We have so far mapped nine of these mutants and two map to regions of the genome distinct from the location of any previously identified dopamine-signaling components. We are currently in the process of further characterizing these mutants.

Khursheed A Wani et al. (2005) International Worm Meeting "C. elegans A, B and B3- type cyclins have both distinct and overlapping functions"

Khursheed A Wani, Sander Van Den Heuvel, Monique A Lorson, John S Satterlee, Jessica Koranda

[International Worm Meeting, 2005]

We are interested in understanding the roles of different Cyclin-dependent kinase (Cdk) complexes in the developmental regulation of cell-cycle progression. The C. elegans cell cycle uses multiple Cdks and various cyclins, possibly representing the entire range of Cyclin/Cdk complexes in mammals. C. elegans and other metazoans express distinct A- and B-type cyclins, as well as a cyclin B3 protein that shares specific motifs with both other mitotic cyclins. The evolutionary conservation of these distinct cyclin subfamilies may point to specificity in function. However, genetic studies in Drosophila have demonstrated that neither cyclin B nor cyclin B3 is essential for viability, and that cyclin A, B and B3 all cooperate during mitosis [Jacobs et al, Genes Dev. 12(23),1998].In previous unpublished studies, we observed that C. elegans B-type cyclins CYB-1 and CYB-3 show similar developmental expression patterns and largely overlapping subcellular localizations. However, inactivation of either gene by RNAi resulted in specific meiotic and mitotic defects. Inhibition of both cyclins simultaneously resulted in an earlier and more dramatic cell-cycle arrest and resembled cdk-1/ncc-1 RNAi. These results indicated that cyb-1 and cyb-3 have specific as well as overlapping M-phase functions. We wanted to expand these observations by including null mutations and characterization of cya-1 cyclin A. We generated a cya-1 deletion allele in a PCR-based approach. cya-1(he158) homozygous mutants and cya-1(RNAi) animals displayed a late larval arrest and protruding vulva phenotype. Stronger and more variable larval defects were seen in animals homozygous for either the cyb-1(gk35) or cyb-3(gk195) deletion allele (kindly provided by the C. elegans Knockout Consortium). Combination of cya-1 RNA and cyb-3(gk195) further increased the defects and resulted in a high percentage embryonic lethality. These results confirm and expand the RNAi-based observations, and indicate that cya-1, cyb-1 and cyb-3 each are individually required but also have overlapping functions.

Gonzalez, Xavier et al. (2021) International Worm Meeting "Defining the microbiota host defense response in C. elegans"

E. Irazoqui , Javier, A. Wani , Khursheed, Gonzalez, Xavier

[International Worm Meeting, 2021]

The intestine is in constant contact with the external environment that predisposes it to harmful microorganisms. Therefore, there is an urgent need to understand the fundamental mechanisms that are used by a host to induce a defense response in intestinal epithelial cells. Given the inherent complexity of the mammalian intestine, it is challenging to parse out host-pathogen interactions in a whole-animal model. The intestine of the nematode C. elegans shares extensive morphological and functional similarities with the mammalian intestine, making it a powerful whole-animal model to dissect interactions between intestinal epithelial cells and microbes in vivo. Research done over the last several years has identified conserved innate host defense pathways in C. elegans, including the p38 mitogen-activated protein kinase (MAPK), Wingless-Integration site mutant (Wnt), and transcription factor EB (TFEB), among others. What is not known is the extent to which these innate host defense pathways are critical for the survival of C. elegans in its natural habitat. To approach this question, we asked which of the host defense pathways are activated by the natural microbiota of C. elegans. We identified specific microbiota that are able to elicit Wnt and HLH-30/TFEB activation. In addition, we identified distinct expression of FMO-2, a flavin-containing monooxygenase that is required for host defense, by Gram-positive microbiota but not by Gram-negative microbiota. Future directions are to define the distinct effector function of innate immune pathways in the context of microbial communities of C. elegans.

Quartey MO et al. (2021) Sci Rep "The A(1-38) peptide is a negative regulator of the A(1-42) peptide implicated in Alzheimer disease progression."

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).

Danielle Thierry-Mieg et al. (2003) Worm Breeder's Gazette "www.wormgenes.org , a new gene centered database"

Vahan Simonyan, Michel Potdevin, Mark Sienkiewicz, Yuji KOHARA, Jean Thierry-Mieg, Danielle Thierry-Mieg, Tadasu SHIN-I

[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.

Tangrodchanapong T et al. (2020) Front Pharmacol "Frondoside A Attenuates Amyloid- Proteotoxicity in Transgenic Caenorhabditis elegans by Suppressing Its Formation."

Tangrodchanapong T, Sobhon P, Meemon K

[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.

Hodgkin JA (1998) International Journal of Developmental Biology "Seven types of pleiotropy."

Hodgkin JA

[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.