Wolinsky EJ (1991) International C. elegans Meeting "DEG-1 ALLELIC INTERACTIONS."

Wolinsky EJ

[International C. elegans Meeting, 1991]

deg-1 is a member of family of genes in which dominant mutations confer a phenotype of degeneration of specific neurons (Nature 349:588) . It encodes a putative membrane protein (Nature 345:410) that may act as a cell surface receptor for an as yet unknown ligand. We have observed interactions between different deg-1 alleles in trans that suggest deg-1 molecules can influence each other's functioning. The dominant, neurodegeneration-causing allele u38 contains the same missense mutation (ala->val) as found in dominant, neurodegeneration- causing mutations of mec-4. We have identified a second missense mutation, u38u424, two codons downstream (gly- > arg) which inactivates the degeneration phenotype. Homozygous u38u424 animals appear wild-type, however u38u424/u38 + heterozygotes show partial, cold-sensitive suppression of the degeneration phenotype (WBG 11(4) :104). High copy number arrays of a u38u424 genomic deg-1 cosmid clone completely suppress two chromosomal copies of the u38 allele, independent of temperature. These results suggest that the doubly mutant deg-1 protein competes with the degeneration-causing isoform, either in the formation of deg-1 protein multimers or in interactions with other molecules. The same u38u424 high-copy arrays do not suppress mec-4(e161 1)-induced degenerations, suggesting that this competition does not involve the mec-6 gene product. mec-6 recessive mutations suppress both deg-l and mec-4 dominant mutations (Nature 345:410). We have recently noticed a new behavioral phenotype associated with the u38 mutation. u38/+ heterozygotes continue to lay eggs after transfer to M9 buffer in microtitre wells. u38 homozygotes are also egg-laying constitutive in this assay when compared to wild- type, but to a significantly lesser degree. u38u424 and deg-1 null alleles behave as wild-type in this assay. We are curious about the cellular focus of this phenotype, as well as the means by which it seems to be accentuated in trans by the wild-type allele. We will also report on progress in genomic sequencing that allows prediction of deg- 1 coding sequence upstream from that of the previously published partial cDNA clones (Nature 345:410), as well as sequence analysis of an EMS-induced deletion and of a Tc1 insertion mutation.

Wolinsky EJ et al. (1987) International C. elegans Meeting "a Tc1 insertion at the deg-1 locus."

Wolinsky EJ, Chalfie M

[International C. elegans Meeting, 1987]

Wolinsky EJ et al. (1989) International C. elegans Meeting "the deg-1 gene may encode a cell-membrane receptor."

Wolinsky EJ, Chalfie M

[International C. elegans Meeting, 1989]

Wolinsky EJ et al. (1985) International C. elegans Meeting "pharmacological and genetic studies of C elegans egge laying."

Horvitz HR, Wolinsky EJ

[International C. elegans Meeting, 1985]

Shreffler W et al. (1995) International C. elegans Meeting "A NETWORK OF GENES REGULATES ION CHANNEL FUNCTION"

Shreffler W, Wolinsky EJ

[International C. elegans Meeting, 1995]

Genetic evidence suggests that unc-8 LGIV is a member, or interacts with amember, of the deg-1 gene family (Genetics139:1261). The dominant mutations unc-8(n491) and unc-8(e15) cause motorneuron swelling, and, like dominant deg-1 and mec-4 mutations, are suppressed by recessive mec-6 LGI mutations. Mammalian deg-1 family homologs encode subunits of amiloride-sensitive sodium channels essential for cellular and systemic salt and water balance. Ongoing genetic screens for mutations that suppress or enhance unc-8 mutant phenotypes have so far yielded seven mutations in six new genes. Unselected phenotypes of isolated suppressor mutations are consistent with roles for the affected gene products in osmoregulation. For example, the sup-40(lb130) LGI mutation isolated as a dominant suppressor of unc-8 dominant mutations also recessively confers phenotypes of hypodermal nuclear and oocyte swelling. Unselected phenotypes of two additional mutations interacting with unc-8 are described here. enu-2(lb140) LGIII (between pha-1 and dpy-18) was isolated in a screen for mutations enhancing the uncoordinated phenotype of unc-8(e49). It confers a weak uncoordinated phenotype in an unc-8(+) background, and complements unc-119. At 25oC, half of enu-2(lb140);unc-8(+) adults contain multiple vacuoles within hypodermis and body muscle. In enu-2(lb140);unc-8(e49) double mutants, penetrance is 100% and the size and number of vacuoles is also increased. Only 15% of enu-2(lb140);unc-8 (e15lb55) display these vacuoles (lb55 is a putative transposon insertion). These results suggest that the unc-8 and enu-2 gene products interact in osmoregulation of hypodermis and muscle, as well as in locomotion. mec-6 mutations do not suppress the enu-2(lb140) swelling phenotype; surprisingly, mec-6(e1342);enu-2(lb140) animals are severely uncoordinated. Thus, mec-6 may also interact with enu-2. sup-42(lb88) X recessively suppresses unc-8 dominant phenotypes and causes partially penetrant embryonic lethality. The fractions of unhatched eggs of unc-8(n491);sup-42(+), unc-8(+);sup-42(lb88), unc-8(n491);sup-42(lb88), unc-8(e15lb55);sup-42(lb88) and mec-6(e1342);unc-8(n491);sup-42(lb88) are, respectively, 10%, 40%, 60%, 15%, and 10%. Arrested embryos, ranging from pre-comma to motile stages, contain swollen cells. These results suggest that all three genes interact early in development as well as in embryonically-born motorneurons.

Dyomina K et al. (1993) International C. elegans Meeting "Structure of the deg-1 locus."

Dyomina K, Wolinsky EJ

[International C. elegans Meeting, 1993]

Gorina S et al. (1993) International C. elegans Meeting "A role for eicosanoids in neural signalling and gonad function of C. elegans."

Gorina S, Hsu M, Wolinsky EJ, Magardino T

[International C. elegans Meeting, 1993]

Sekigawa, K. et al. (2019) International Worm Meeting "Age-related changes in muscle of a premature aging model in C. elegans ."

Sekigawa, K., Ishii, N., Yanase, S., Otsuka, Y.

[International Worm Meeting, 2019]

In mammals including humans, the age-related loss of muscle mass and function is known as sarcopenia. Although the mechanisms underlying the development of sarcopenia are multifactorial, apoptosis has been shown to play a role in muscle loss during aging [1]. Recently, age-related muscle loss has also been found in the nematode C. elegans during normal aging. As in humans, age-related muscle loss in C. elegans leads to decreased mobility and serves as a marker for increased mortality [2, 3]. In this study, we aimed to detect age-associated muscle loss in the short-lived mev-1(kn1) mutant, which is a model of premature aging in C. elegans. The mev-1 gene encodes a large subunit of the enzyme succinate dehydrogenase cytochrome b, which is a component of complex II in the mitochondrial electron transport chain. Mutation of the gene causes an increase in mitochondrial oxidative stress, thereby induces abnormal apoptosis in embryonic development and shortenes the lifespan [4]. Here, we show a smaller body size in the L1 larval but not adult stage of the mev-1 mutant compared with the wild-type as well as the histopathological changes in muscle with premature aging. References 1. Always SE et al. (2011) Aging and apoptosis in muscle, In: Handbook of the biology of aging, 7th edition (eds. Masoro EJ, Austad SN), Academic Press, London, pp. 63-118 2. Herndon LA et al. (2002) Stochastic and genetic factors influence tissue-specific decline in ageing C. elegans, Nature 419: 808-814 3. Fishen AL (2004) Of worms and women: Sarcopenia and its role in disability and mortality, J Am Geriatr Soc 52: 1185-1190 4. Ishii N et al. (1998) A mutation in succinate dehydrogenase cytochrome b causes oxidative stress and ageing in nematodes. Nature 394: 694-697

Yanase, Sumino et al. (2021) International Worm Meeting "Recovery of Muscle Function Dependent on the Impaired Cell Death in a C. elegans Premature Aging Model"

Suzuki, Yu, Yasuda, Kayo, Ishii, Naoaki, Yanase, Sumino, Sekigawa, Kota, Otsuka, Yuko

[International Worm Meeting, 2021]

In mammals including humans, the age-related losses of muscle mass and function are known as sarcopenia. Although the mechanisms underlying the development of sarcopenia are multifactorial, apoptosis has been shown to play a role in muscle loss during aging [1]. Recently, age-related muscle loss has also been found in the nematode C. elegans during normal aging. As in humans, age-related muscle loss in C. elegans leads to decreased mobility and serves as a marker for increased mortality [2, 3]. Here we examined the difference in age-associated pharyngeal muscle function between the short-lived mev-1(kn1) and the phenotype of deficient cell death (mev-1;ced-3 mutant), however, have shown no significant histopathological change in the loss of pharyngeal muscle mass. The mev-1 gene encodes a large subunit of the enzyme succinate dehydrogenase cytochrome b, which is a component of complex II in the mitochondrial electron transport chain. Mutation of the gene causes an increase in mitochondrial oxidative stress, thereby induces abnormal apoptosis in embryonic development and shortenes the lifespan [4]. Moreover, we aim to detect age-related difference in gene expression concerned with the cell death signaling using both mutants. References 1. Always SE et al. (2011) Aging and apoptosis in muscle, In: Handbook of the biology of aging, 7th edition (eds. Masoro EJ, Austad SN), Academic Press, London, pp. 63-118 2. Herndon LA et al. (2002) Stochastic and genetic factors influence tissue-specific decline in ageing C. elegans, Nature 419: 808-814 3. Fishen AL (2004) Of worms and women: Sarcopenia and its role in disability and mortality, J Am Geriatr Soc 52: 1185-1190 4. Ishii N et al. (1998) A mutation in succinate dehydrogenase cytochrome b causes oxidative stress and ageing in nematodes. Nature 394: 694-697

Miriam B Goodman et al. (2003) International Worm Meeting "Mapping the pore of the amiloride-sensitive channel (ASC) needed for touch sensation in C. elegans"

Miriam B Goodman, Zhiwen Liao

[International Worm Meeting, 2003]

The ion channel formed by MEC-4 and MEC-10 is proposed to mediate sensory mechanotransduction in C. elegans touch cells. Initial efforts to reconstitute this channel in heterologous cells have shown that MEC-4 and MEC-10 form an amiloride-sensitive, Na+-selective ion channel complex together with MEC-2 stomatin and MEC-6 paraoxonase (1, 2). We are using double mutant cycle analysis to map the interaction surface between the pore-forming subunits, MEC-4 and MEC-10. Our general approach is to co-express wild-type and mutant forms of MEC-4 and MEC-10 and identify interacting amino acid residues using the antagonist, amiloride, as a probe. Preliminary findings have already identified one such interaction site: the d position. The importance of the d position was first highlighted by gain-of-function mutations in genes encoding ASC proteins in C. elegans (3, 4) that cause neuronal degeneration in vivo. In both MEC-4 and MEC-10, the wild-type residue is an alanine. Thus far, we have analyzed mutations that cause neuronal degeneration in vivo (T, V, and D) and mutations that we predict will be similar to wild-type (S, C). Our initial results are consistent with the idea that d position forms part the interaction surface between MEC-4 and MEC-10. We speculate that residues at this position contribute to a gate that regulates access to the amiloride binding site in the ion channel pore. 1. M. B. Goodman et al., Nature 415, 1039-42. (2002); 2. D. S. Chelur et al., Nature 420, 669-673 (2002); 3. M. Driscoll, M. Chalfie, Nature 349, 588-593 (1991); 4. M. Chalfie, E. Wolinsky, Nature 345, 410-416 (1990).