Maxfield, A. et al. (2019) International Worm Meeting "The regulation of Rab activity in trafficking to gut granules."

Morris, C., Voss, L., Lavoy, S., Maxfield, A., Foster, O., Handa, S., Hermann, G.

[International Worm Meeting, 2019]

C. elegans gut granules are intestinally restricted lysosome-related organelles (LROs) that are distinct from, and coexist with, conventional lysosomes. The formation of gut granules requires the Rab32/38 family member GLO-1. Our genetic and cellular data suggest that GLO-3 and CCZ-1 function as a guanine nucleotide exchange factor (GEF) for GLO-1 recruiting it to the gut granule membrane. We present yeast 2- and 3-hybrid results that point to direct physical interactions between these three proteins. Using rescuing forms of glo-1 and glo-3, where gfp was inserted into its genomic locus, we have identified the subcellular sites where GLO-1 is likely activated and localized. By screening our collection of gut granule biogenesis mutants we found that wht-2(-) mutants lead to the loss of GLO-1 from gut granules similar to glo-3(-) mutants. WHT-2 is an ABCG family membrane transporter, which localizes to the gut granule membrane. wht-2(-) mutants contain partially formed gut granules and in combination with other LRO biogenesis mutants, leads to the disruption of gut granule protein trafficking. Unlike glo-3(-) and ccz-1(-) mutants, a fast nucleotide exchange GLO-1 mutant does not restore the gut granule association of GLO-1 or gut granule formation in wht-2(-) mutants. Instead, WHT-2 is required for the ability of GLO-1 fast nucleotide exchange mutants to bypass the requirement of CCZ-1 and GLO-3 in gut granule biogenesis. Together, these data point to a GEF independent role of WHT-2 in GLO-1 organelle recruitment and activation. This likely requires the membrane transport function of WHT-2, as point mutations that disrupt its ATPase activity cause the loss of GLO-1 from gut granules.

Dane Maxfield et al. (2008) C.elegans Neuronal Development Meeting "Characterizing the Spatiotemporal Dynamics of Glutamate Receptor Complexes in C. elegans"

Frederic Horndli, Andres Maricq, Dane Maxfield, David Madsen, Jerry Mellem, Penelope Brockie

[C.elegans Neuronal Development Meeting, 2008]

Plasticity of the nervous system and how this might facilitate learning and memoryis an intriguing and challenging problem in the field of neuroscience. Glutamate is themajor excitatory neurotransmitter in the brain and mediates rapid neurotransmissionby binding to transmembrane ionotropic glutamate receptors (iGluRs). Regulationof both the subunit composition and the number of iGluRs at synapses underliesforms of synaptic plasticity that may contribute to learning and memory formation.For example, iGluRs are thought to constantly track in and out of synapses bylateral diffusion in the plasma membrane and by cycling between the cell surfaceand intracellular organelles. However, many of these analyses were undertaken incultured neurons and may not faithfully represent the behavior of iGluRs in vivo.Using C. elegans. We have begun to characterize the spatiotemporal dynamics of iGluRs in aliving organism. One component of the glutamate-activated current in C. elegans ismediated by the AMPA-type iGluR subunit GLR-1. We have identi ed two auxiliarysubunits, SOL-1 and STG-1 that are required for GLR-1 function. To form functionalglutamatergic synapses, iGluRs and their auxiliary subunits must be expressed in a specificsubset of neurons and then localized to the proper postsynaptic sites. Oncelocalized, iGluRs must then be maintained at the appropriate density. How are thesedynamic processes regulated? We are currently generating a variety of fluorescently tagged iGluRs that will allow us to address the following questions: What is thestability of iGluRs at synapses? Is trafficking an active or passive process? How doesneural activity affect iGluR turnover at synapses? And, is the trafficking of GLR-1,SOL-1 and STG-1 interdependent? Ultimately, we would like to identify genes thatare required for these processes. By characterizing the dynamic behavior of iGluRsin C. elegans, we hope to better understand the basic mechanism controlling synapticsignaling and the neural control of behavior.

Mintzer EA et al. (2002) FEBS Lett "Behavior of a photoactivatable analog of cholesterol, 6-photocholesterol, in model membranes."

Mintzer EA, Wilschut J, Waarts BL, Bittman R

[FEBS Lett, 2002]

6-Photocholesterol, a new photoactivatable analog of cholesterol in which a diazirine functionality replaces the 5,6-double bond in the steroid nucleus, was used recently to identify cholesterol-binding proteins in neuroendocrine cells [Thiele, C., Hannah, M.J., Farenholz, F. and Huttner, W.B. (2000) Nat. Cell Biol. 2, 42-49], to track the distribution and transport of cholesterol in Caenorhabditis elegans [Matyash, V., Geier, C., Henske, A., Mukherjee, S., Hirsh, D., Thiele, C., Grant, B., Maxfield, F.R. and Kurzchalia, T.V. (2001) Mol. Biol. Cell 12, 1725-1736], and to probe lipid-protein interactions in oligodendrocytes [Simons, M., Kramer, E.M., Thiele, C., Stoffel, W. and Trotter, J. (2000) J. Cell Biol. 151, 143-154]. To determine whether 6-photocholesterol is a faithful mimetic of cholesterol we analyzed the ability of this probe, under conditions in which it is not photoactivated to a carbene, to substitute for cholesterol in two unrelated assays: (1) to condense 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine monomolecular films and (2) to mediate the fusion of two alphaviruses (Semliki Forest and Sindbis) with liposomes. The results suggest that this analog is a suitable photoprobe of cholesterol.

Voss L et al. (2019) Genetics "An ABCG Transporter Functions in Rab Localization and Lysosome-Related Organelle Biogenesis in Caenorhabditis elegans."

Maxfield A, Peloza K, Brandt JN, Harper L, Foster OK, Harp M, Rambo FM, King B, Eichten V, Voss L, Morris C, Lavoy S, Handa S, Hermann GJ

[Genetics, 2019]

ABC transporters couple ATP hydrolysis to the transport of substrates across cellular membranes. This protein superfamily has diverse activities resulting from differences in their cargo and subcellular localization. Our work investigates the role of the ABCG family member WHT-2 in the biogenesis of gut granules, a <i>Caenorhabditis elegans</i> lysosome-related organelle. In addition to being required for the accumulation of birefringent material within gut granules, WHT-2 is necessary for the localization of gut granule proteins when trafficking pathways to this organelle are partially disrupted. The role of WHT-2 in gut granule protein targeting is likely linked to its function in Rab GTPase localization. We show that WHT-2 promotes the gut granule association of the Rab32 family member GLO-1 and the endolysosomal RAB-7, identifying a novel function for an ABC transporter. WHT-2 localizes to gut granules where it could play a direct role in controlling Rab localization. Loss of CCZ-1 and GLO-3, which likely function as a guanine nucleotide exchange factor (GEF) for GLO-1, lead to similar disruption of GLO-1 localization. We show that CCZ-1, like GLO-3, is localized to gut granules. WHT-2 does not direct the gut granule association of the GLO-1 GEF and our results point to WHT-2 functioning differently than GLO-3 and CCZ-1. Point mutations in WHT-2 that inhibit its transport activity, but not its subcellular localization, lead to the loss of GLO-1 from gut granules, while other WHT-2 activities are not completely disrupted, suggesting that WHT-2 functions in organelle biogenesis through transport-dependent and transport-independent activities.

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.

Tuck S (2011) Curr Biol "Extracellular vesicles: budding regulated by a phosphatidylethanolamine translocase."

Tuck S

[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.

Viney ME et al. (2004) Naturwissenschaften "Is dauer pheromone of Caenorhabditis elegans really a pheromone?"

Viney ME, Franks NR

[Naturwissenschaften, 2004]

Animals respond to signals and cues in their environment. The difference between a signal (e.g. a pheromone) and a cue (e.g. a waste product) is that the information content of a signal is subject to natural selection, whereas that of a cue is not. The model free-living nematode Caenorhabditis elegans forms an alternative developmental morph (the dauer larva) in response to a so-called 'dauer pheromone', produced by all worms. We suggest that the production of 'dauer pheromone' has no fitness advantage for an individual worm and therefore we propose that 'dauer pheromone' is not a signal, but a cue. Thus, it should not be called a pheromone.