Goldstein P et al. (1989) Cytobios "Resistance to lethal levels of diethylstilboestrol in the nematode Caenorhabditis elegans."

Goldstein P, Aun J, Watts M

[Cytobios, 1989]

Concentrations of diethylstilboestrol (DES) exceeding 100 microM are normally fatal to all living tissues due to inhibition of cell division and other cell processes. However, in Caenorhabditis elegans, with increasing levels of DES, there was an observed decrease in fertility and fecundity (99%), although a small percentage of the population (1%) survived concentrations as high as 400 microM DES. Uptake studies, using tritiated-DES liquid scintillation and ELISA analysis, revealed that uptake exhibited saturation at 100 microM and levels exceeding 100 microM resulted in no further biological response. Thus, ultrastructural morphology and viability of the organism was unchanged after the DES saturation point.

Goldstein P et al. (1992) Chromatin "Trans-generational effects of diethylstilboestrol spermatogenesis and absence of synaptonemal complexes in the him-8 mutant of Caenorhabditis elegans."

Huang J-X, Goldstein P

[Chromatin, 1992]

This work represents the first comprehensive study of the effects of diethylstilboestrol (DES) on early spermatogenesis through the third generation. Exposure to a DES concentration of 12.5 ug/ml resulted in a significant decrease in the third generation, presumably due to genetic load. In some aspects, the reaction of males and hermaphrodites for DES were similar, such that decreased fecundity and ultrastructral changes were observed in both forms. Ultrastructural analyses demonstrated that the decrease in the number of offspring in him-8 C. elegans was associated with the production of abnormal speratocytes. Males were more sensitive to DES than hermaphrodites. At a DES concentration of 1.25 ug/ml, no morphological changes were observed in hermaphrodites, while nuclear architecture was compromised in males. In addition, at this low DES concentration, synaptonemal complexes were present in the hermaphrodites but absent in males.

Yassin L et al. (2001) Mol Cell Neurosci "Characterization of the deg-3/des-2 receptor: a nicotinic acetylcholine receptor that mutates to cause neuronal degeneration."

Gillo B, Yassin L, Treinin M, Eshel M, Halevi S, Kahan T

[Mol Cell Neurosci, 2001]

The nicotinic acetylcholine receptor family (nAChR) is a large family of acetylcholine-gated cation channels. Here we characterize the Caenorhabditis elegans DEG-3/DES-2 nAChR, a receptor identified due to its involvement in neuronal degeneration. Pharmacological analysis of a DEG-3/DES-2 receptor expressed in Xenopus oocytes shows that this receptor is preferentially activated by choline. This choline sensitivity of the DEG-3/DES-2 channel can explain its role in neuronal degeneration, as shown by the toxic effects of choline on oocytes expressing the mutant DEG-3/DES-2 channel. We also show that in C. elegans the DEG-3/DES-2 receptor is localized to nonsynaptic regions, including the sensory endings of chemosensory neurons. This localization is in agreement with a role for this receptor in chemosensation of choline, as inferred from a defect in chemotaxis for choline seen in deg-3 mutants. Thus, this work also provides evidence for the diversity of nonsynaptic activities associated with nAChRs.

Goldstein P (1986) Mutat Res "Nuclear aberrations and loss of synaptonemal complexes in response to diethylstilbestrol (DES) in Caenorhabditis elegans hermaphrodites."

Goldstein P

[Mutat Res, 1986]

In Caenorhabditis elegans, loss of viability and fertility is observed after treatment with DES. The decrease in life span is associated with senescent morphology of meiotic prophase nuclei, such that nuclei from young and old specimens cannot be differentiated. Aging in oocytes at the pachytene stage of meiotic prophase is manifested by nucleo-cytoplasmic aberrations, increased density of the nucleoplasm and cytoplasm and decrease in numbers of mitochondria. Increasing concentrations of DES are characterized by concomitant decrease in fertility and increased production of abnormal gametes. At DES concentrations higher than 1.25 micrograms/ml, synaptonemal complexes (SC) are absent from the nuclei, thus, effective pairing and segregation of homologous chromosomes is not possible. The absence of SCs may be the result of: a premeiotic colchicine-like effect that influences pairing of chromosomes; changes in the structure of the DNA due to DES binding that results in changes in expression of the DNA; and changes in temporal DNA synthesis in response to DES. Since the SC is essential for regulating pairing and subsequent separation of bivalents, the lack of an SC explains the loss of fertility, due to the production of unbalanced gametes, observed in DES-treated specimens.

Hanna Farah et al. (2006) Neuronal Development, Synaptic Function, and Behavior Meeting "Preferential Interactions of RIC-3 with nAChR Subunits"

Millet Treinin, Hagit Cohen Ben-Ami, Hanna Farah

[Neuronal Development, Synaptic Function, and Behavior Meeting, 2006]

In C. elegans RIC-3 is required for the maturation of multiple nicotinic acetylcholine receptors, including the DEG-3/DES-2 neuronal nAChR. RIC-3 belongs to a conserved gene family. Members of this family all encode two transmembrane domains followed by one or two coiled-coil domains. Analysis of the effects of RIC-3 on the DEG-3/DES-2 receptor in Xenopus leavis oocytes shows affects on both receptor peak current amplitudes and on receptor properties. RIC-3's effects on DEG-3/DES-2 properties are similar to the effects of increasing the DEG-3 to DES-2 subunit ratio, suggesting that RIC-3 may preferentially enhance maturation of DEG-3 rich receptors. All effects of RIC-3 in Xenopus oocytes are mediated by a short sequence encompassing the transmembrane domains but lacking the coiled-coil domains. We now show that effects on both receptor properties and receptor peak amplitudes are reduced by mutation of a single conserved residue in the second transmembrane domain. In addition we show that RIC-3 interacts with DEG-3 in the absence of DES-2 but not with DES-2 in the absence of DEG-3. Last we show that RIC-3 enhances surface expression of DEG-3 but not of DES-2. Thus our analysis shows a linkage between the different effects of RIC-3 on the DEG-3/DES-2 receptor, and shows that effects on receptor properties can be explained by a preferential interaction of RIC-3 with the DEG-3 subunit, leading to increased surface expression of DEG-3 rich receptors.

Goldstein P (1985) Worm Breeder's Gazette "nuclear aberrations and loss of synaptonemal complexes in response to diethylstilbestrol in Caenorhabditis elegans hermaphrodites."

Goldstein P

[Worm Breeder's Gazette, 1985]

In Caenorhabditis viability and fertility is observed after treatment with DES. The decrease in life span is associated with senescent morphology of meiotic prophase nuclei, such that nuclei from young and old specimens cannot be differentiated. Aging in oocytes at the pachytene stage of meiotic prophase is manifested by nucleo-cytoplasmic aberrations, increased density of the nucleoplasm and cytoplasm and decrease in numbers of mitochondria. Increasing concentrations of DES are characterized by concomittant decrease in fertility and increased production of abnormal gametes. At DES concentrations higher than 1.25 g/ml, synaptonemal complexes( SC) are absent from the nuclei, thus, effective pairing and segregation of homologous chromosomes is not possible. The absence of SCs may be the result of: 1) a premeiotic colchicine effect that influences pairing of chromosomes; 2) changes in the structure of the DNA due to DES binding that results in changes in expression of the DNA; and 3) changes in temporal DNA synthesis in response to DES. Since the SC is essential for regulating pairing and subsequent separation of bivalents, the lack of an SC explains the loss of fertility, due to the production of unbalanced gametes, observed in DES treated specimens.

Lina Yassin et al. (2003) International Worm Meeting "DEG-3 function and dysfunction"

Lina Yassin, Millet Treinin

[International Worm Meeting, 2003]

DEG-3 is a subunit of a nicotinic acetylcholine receptor (nAChR) that can mutate to cause neuronal degeneration. In Xenopus oocytes DEG-3 together with DES-2, another nAChR subunit, form a channel. Analysis of this channel led to a model whereby physiological concentrations of choline, an agonist of the DEG-3/DES-2 channel, lead to constitutive activity of the mutant channel, leading to excessive entry of calcium and cell death. Analysis of the DEG-3/DES-2 channel in oocytes provided basic insights into the causes of neuronal degeneration. But the analysis also implied differences between DEG-3/DES-2 channel activity in oocytes and in native neurons. To understand these differences we added to the oocyte system factors likely to affect DEG-3 channel activity in C. elegans. Two such factors, co-expression with RIC-3 and chronic exposure to choline were found to modify DEG-3/DES-2 channel activity. Choline is expected to exert this effect in-vivo because it is a necessary metabolite constitutively found in most organisms. RIC-3 is required for maturation of multiple nAChRs (including DEG-3) in C. elegans and enhances nAChR surface expression in oocytes. Interestingly manipulations that modify DEG-3/DES-2 channel stoichiometry mimic the effects of RIC-3 on channel properties, suggesting a second role for RIC-3 in regulating subunit stoichiometry. Taken together the identification of factors that modify DEG-3/DES-2 channel activity improves our understanding of its normal and pathological activity, and suggests that in-vivo these factors and others, yet to be identified, regulate receptor numbers and properties.

Nathalie Pujol et al. (2001) Worm Breeder's Gazette "Ver midi IV"

Jonathan Ewbank, Nathalie Pujol

[Worm Breeder's Gazette, 2001]

La quatrieme reunion annuelle des equipes francaises ayant un interet pour C. elegans se tiendra le Vendredi 23 fevrier 2001 a Luminy, Marseille. Contact: pujol@ibdm.univ-mrs.fr ewbank@ciml.univ-mrs.fr

Hansen TVA et al. (2022) Molecules "The Caenorhabditis elegans DEG-3/DES-2 Channel Is a Betaine-Gated Receptor Insensitive to Monepantel."

Toutain CE, Charvet CL, Courtot E, Sager H, Hansen TVA, Neveu C

[Molecules, 2022]

Natural plant compounds, such as betaine, are described to have nematocidal properties. Betaine also acts as a neurotransmitter in the free-living model nematode <i>Caenorhabditis elegans</i>, where it is required for normal motility. Worm motility is mediated by nicotinic acetylcholine receptors (nAChRs), including subunits from the nematode-specific DEG-3 group. Not all types of nAChRs in this group are associated with motility, and one of these is the DEG-3/DES-2 channel from <i>C. elegans</i>, which is involved in nociception and possibly chemotaxis. Interestingly, the activity of DEG-3/DES-2 channel from the parasitic nematode of ruminants, <i>Haemonchus contortus</i>, is modulated by monepantel and its sulfone metabolite, which belong to the amino-acetonitrile derivative anthelmintic drug class. Here, our aim was to advance the pharmacological knowledge of the DEG-3/DES-2 channel from <i>C. elegans</i> by functionally expressing the DEG-3/DES-2 channel in <i>Xenopus laevis</i> oocytes and using two-electrode voltage-clamp electrophysiology. We found that the DEG-3/DES-2 channel was more sensitive to betaine than ACh and choline, but insensitive to monepantel and monepantel sulfone when used as direct agonists and as allosteric modulators in co-application with betaine. These findings provide important insight into the pharmacology of DEG-3/DES-2 from <i>C. elegans</i> and highlight the pharmacological differences between non-parasitic and parasitic nematode species.

Cohen Ben-Ami H et al. (2005) J Biol Chem "RIC-3 affects properties and quantity of nicotinic acetylcholine receptors via a mechanism that does not require the coiled-coil domains."

Treinin M, Cohen Ben-Ami H, Yassin L, Michaeli A, Eshel M, Farah H

[J Biol Chem, 2005]

Members of the RIC-3 gene family are effectors of nicotinic acetylcholine receptor (nAChR) expression in vertebrates and invertebrates. In Caenorhabditis elegans RIC-3 is needed for functional expression of multiple nAChRs, including the DEG-3/DES-2 nAChR. Effects of RIC-3 on DEG-3/DES-2 functional expression are found in vivo and following heterologous expression in Xenopus leavis oocytes. We now show that in X. leavis oocytes RIC-3 also affects the kinetics and agonist affinity properties of the DEG-3/DES-2 receptor. Because these effects are mimicked by increasing the ratio of DEG-3 subunits within DEG-3/DES-2 receptors, this suggests that RIC-3 may preferentially promote maturation of DEG-3-rich receptors. Indeed, effects of RIC-3 on functional expression of DEG-3/DES-2 positively correlate with the DEG-3 to DES-2 ratio. All RIC-3 family members have two transmembrane domains followed by one or two coiled-coil domains. Here we show that the effects of RIC-3 on functional expression and on receptor properties are mediated by the transmembrane domains and do not require the coiled-coil domains. In agreement with this, mammals express a RIC-3 transcript lacking the coiled-coil domain that is capable of promoting DEG-3/DES-2 functional expression. Last, we show that RIC-3 affects DEG-3 quantity, suggesting stabilization of receptors or receptor intermediates by RIC-3. Together our results suggest that subunit-specific interactions of RIC-3 with nAChR subunits, mediated by the transmembrane domains, are sufficient for the effects of RIC-3 on nAChR quantity and quality.