An unexpected role for the conserved ADAM-family metalloprotease ADM-2 in Caenorhabditis elegans molting

Molting is a widespread developmental process in which the external extracellular matrix (ECM), the cuticle, is remodeled to allow for organismal growth and environmental adaptation. Studies in the nematode Caenorhabditis elegans have identified a diverse set of molting-associated factors including signaling molecules, intracellular trafficking regulators, ECM components, and ECM-modifying enzymes such as matrix metalloproteases. C. elegans NEKL-2 and NEKL-3, two conserved members of the NEK family of protein kinases, are essential for molting and promote the endocytosis of environmental steroid-hormone precursors by the epidermis. Steroids in turn drive the cyclic induction of many genes required for molting. Here we report a novel role for the sole C. elegans ADAM-meltrin metalloprotease family member, ADM-2, as a negative regulator of molting. Whereas loss of adm-2 led to strong suppression of molting defects in partial loss-of-function nekl mutants, overexpression of ADM-2 induced molting defects in wild-type animals. CRISPR genome editing implicated the Zn-binding motif within the metalloprotease domain as critical for mediating the effects of ADM-2 on molting. ADM-2 is expressed in the epidermis, and its trafficking through the endo-lysosomal network was disrupted after NEKL depletion. We also identified the epidermally expressed low-density lipoprotein receptor-related protein, LRP-1, as a candidate target of ADM-2 regulation. Whereas loss of ADM-2 activity led to the upregulation of LRP-1, ADM-2 overexpression caused a reduction in LRP-1 abundance, suggesting that ADM-2 may function as a sheddase for LRP-1. We propose that loss of adm-2 suppresses molting defects in nekl mutants by eliminating a negative regulator of LRP-1, thereby compensating for defects in the efficiency of LRP-1 and sterol uptake. Our findings emphasize the importance of endocytic trafficking for both the internalization of factors that promote molting and the removal of proteins that would otherwise be deleterious to the molting process.

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Steroid hormones sulfatase inactivation extends lifespan and ameliorates age-related diseases

Nature Communications ◽

10.1038/s41467-020-20269-y ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Mercedes M. Pérez-Jiménez ◽

José M. Monje-Moreno ◽

Ana María Brokate-Llanos ◽

Mónica Venegas-Calerón ◽

Alicia Sánchez-García ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Caenorhabditis Elegans ◽

Protein Aggregation ◽

Steroid Hormones ◽

Sensory Neurons ◽

Environmental Cues ◽

Steroid Sulfatase ◽

Loss Of Function ◽

C Elegans ◽

Age Related

AbstractAging and fertility are two interconnected processes. From invertebrates to mammals, absence of the germline increases longevity. Here we show that loss of function of sul-2, the Caenorhabditis elegans steroid sulfatase (STS), raises the pool of sulfated steroid hormones, increases longevity and ameliorates protein aggregation diseases. This increased longevity requires factors involved in germline-mediated longevity (daf-16, daf-12, kri-1, tcer-1 and daf-36 genes) although sul-2 mutations do not affect fertility. Interestingly, sul-2 is only expressed in sensory neurons, suggesting a regulation of sulfated hormones state by environmental cues. Treatment with the specific STS inhibitor STX64, as well as with testosterone-derived sulfated hormones reproduces the longevity phenotype of sul-2 mutants. Remarkably, those treatments ameliorate protein aggregation diseases in C. elegans, and STX64 also Alzheimer’s disease in a mammalian model. These results open the possibility of reallocating steroid sulfatase inhibitors or derivates for the treatment of aging and aging related diseases.

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A Cuticle Collagen Encoded by the lon-3 Gene May Be a Target of TGF-β Signaling in Determining Caenorhabditis elegans Body Shape

Genetics ◽

10.1093/genetics/162.4.1631 ◽

2002 ◽

Vol 162 (4) ◽

pp. 1631-1639

Author(s):

Yo Suzuki ◽

Gail A Morris ◽

Min Han ◽

William B Wood

Keyword(s):

Caenorhabditis Elegans ◽

Body Shape ◽

Small Body ◽

Dependent Manner ◽

Loss Of Function ◽

Cellular Mechanisms ◽

C Elegans ◽

Gene Expression Analyses ◽

Dose Dependent

Abstract The signaling pathway initiated by the TGF-β family member DBL-1 in Caenorhabditis elegans controls body shape in a dose-dependent manner. Loss-of-function (lf) mutations in the dbl-1 gene cause a short, small body (Sma phenotype), whereas overexpression of dbl-1 causes a long body (Lon phenotype). To understand the cellular mechanisms underlying these phenotypes, we have isolated suppressors of the Sma phenotype resulting from a dbl-1(lf) mutation. Two of these suppressors are mutations in the lon-3 gene, of which four additional alleles are known. We show that lon-3 encodes a collagen that is a component of the C. elegans cuticle. Genetic and reporter-gene expression analyses suggest that lon-3 is involved in determination of body shape and is post-transcriptionally regulated by the dbl-1 pathway. These results support the possibility that TGF-β signaling controls C. elegans body shape by regulating cuticle composition.

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glp-3 Is Required for Mitosis and Meiosis in the Caenorhabditis elegans Germ Line

Genetics ◽

10.1093/genetics/145.1.111 ◽

1997 ◽

Vol 145 (1) ◽

pp. 111-121 ◽

Cited By ~ 1

Author(s):

Lisa C Kadyk ◽

Eric J Lambie ◽

Judith Kimble

Keyword(s):

Caenorhabditis Elegans ◽

Germ Cells ◽

Germ Line ◽

Stem Cell Population ◽

Phenotypic Characterization ◽

Loss Of Function ◽

Dapi Staining ◽

Cell Cycles ◽

C Elegans ◽

Mitosis And Meiosis

The germ line is the only tissue in Caenorhabditis elegans in which a stem cell population continues to divide mitotically throughout life; hence the cell cycles of the germ line and the soma are regulated differently. Here we report the genetic and phenotypic characterization of the glp-3 gene. In animals homozygous for each of five recessive loss-of-function alleles, germ cells in both hermaphrodites and males fail to progress through mitosis and meiosis, but somatic cells appear to divide normally. Germ cells in animals grown at 15° appear by DAPI staining to be uniformly arrested at the G2/M transition with <20 germ cells per gonad on average, suggesting a checkpoint-mediated arrest. In contrast, germ cells in mutant animals grown at 25° frequently proliferate slowly during adulthood, eventually forming small germ lines with several hundred germ cells. Nevertheless, cells in these small germ lines never undergo meiosis. Double mutant analysis with mutations in other genes affecting germ cell proliferation supports the idea that glp-3 may encode a gene product that is required for the mitotic and meiotic cell cycles in the C. elegans germ line.

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Genetic and Molecular Characterization of the Caenorhabditis elegans Gene, mel-26, a Postmeiotic Negative Regulator of MEI-1, a Meiotic-Specific Spindle Component

Genetics ◽

10.1093/genetics/150.1.119 ◽

1998 ◽

Vol 150 (1) ◽

pp. 119-128

Author(s):

M Rhys Dow ◽

Paul E Mains

Keyword(s):

Caenorhabditis Elegans ◽

Protein Interactions ◽

Negative Regulator ◽

Meiotic Spindle ◽

Loss Of Function ◽

Protein Protein Interactions ◽

Gain Of Function ◽

Recessive Mutations ◽

Female Germline

Abstract We have previously described the gene mei-1, which encodes an essential component of the Caenorhabditis elegans meiotic spindle. When ectopically expressed after the completion of meiosis, mei-1 protein disrupts the function of the mitotic cleavage spindles. In this article, we describe the cloning and the further genetic characterization of mel-26, a postmeiotic negative regulator of mei-1. mel-26 was originally identified by a gain-of-function mutation. We have reverted this mutation to a loss-of-function allele, which has recessive phenotypes identical to the dominant defects of its gain-of-function parent. Both the dominant and recessive mutations of mel-26 result in mei-1 protein ectopically localized in mitotic spindles and centrosomes, leading to small and misoriented cleavage spindles. The loss-of-function mutation was used to clone mel-26 by transformation rescue. As suggested by genetic results indicating that mel-26 is required only maternally, mel-26 mRNA was expressed predominantly in the female germline. The gene encodes a protein that includes the BTB motif, which is thought to play a role in protein-protein interactions.

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Goα Regulates Volatile Anesthetic Action in Caenorhabditis elegans

Genetics ◽

10.1093/genetics/158.2.643 ◽

2001 ◽

Vol 158 (2) ◽

pp. 643-655 ◽

Cited By ~ 1

Author(s):

Bruno van Swinderen ◽

Laura B Metz ◽

Laynie D Shebester ◽

Jane E Mendel ◽

Paul W Sternberg ◽

...

Keyword(s):

Caenorhabditis Elegans ◽

Novel Mutation ◽

Volatile Anesthetic ◽

Loss Of Function ◽

Wild Type ◽

Α Subunit ◽

C Elegans ◽

Missense Mutant ◽

Anesthetic Action ◽

Mutant Phenotypes

Abstract To identify genes controlling volatile anesthetic (VA) action, we have screened through existing Caenorhabditis elegans mutants and found that strains with a reduction in Go signaling are VA resistant. Loss-of-function mutants of the gene goa-1, which codes for the α-subunit of Go, have EC50s for the VA isoflurane of 1.7- to 2.4-fold that of wild type. Strains overexpressing egl-10, which codes for an RGS protein negatively regulating goa-1, are also isoflurane resistant. However, sensitivity to halothane, a structurally distinct VA, is differentially affected by Go pathway mutants. The RGS overexpressing strains, a goa-1 missense mutant found to carry a novel mutation near the GTP-binding domain, and eat-16(rf) mutants, which suppress goa-1(gf) mutations, are all halothane resistant; goa-1(null) mutants have wild-type sensitivities. Double mutant strains carrying mutations in both goa-1 and unc-64, which codes for a neuronal syntaxin previously found to regulate VA sensitivity, show that the syntaxin mutant phenotypes depend in part on goa-1 expression. Pharmacological assays using the cholinesterase inhibitor aldicarb suggest that VAs and GOA-1 similarly downregulate cholinergic neurotransmitter release in C. elegans. Thus, the mechanism of action of VAs in C. elegans is regulated by Goα, and presynaptic Goα-effectors are candidate VA molecular targets.

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Screening for Presenilin Inhibitors Using the Free-Living Nematode, Caenorhabditis elegans

CrossRef Listing of Deleted DOIs ◽

10.1177/1087057103261038 ◽

2004 ◽

Vol 9 (2) ◽

pp. 147-152 ◽

Cited By ~ 19

Author(s):

Brenda R. Ellerbrock ◽

Eileen M. Coscarelli ◽

Mark E. Gurney ◽

Timothy G. Geary

Keyword(s):

Caenorhabditis Elegans ◽

High Throughput Screening ◽

Screening Method ◽

Genetic System ◽

Body Cavity ◽

Egg Laying ◽

The Body ◽

Loss Of Function ◽

C Elegans ◽

Automated Method

Caenorhabditis elegans contains 3 homologs of presenilin genes that are associated with Alzheimer s disease. Loss-of-function mutations in C. elegans genes cause a defect in egg laying. In humans, loss of presenilin-1 (PS1) function reduces amyloid-beta peptide processing from the amyloid protein precursor. Worms were screened for compounds that block egg laying, phenocopying presenilin loss of function. To accommodate even relatively high throughput screening, a semi-automated method to quantify egg laying was devised by measuring the chitinase released into the culture medium. Chitinase is released by hatching eggs, but little is shed into the medium from the body cavity of a hermaphrodite with an egg laying deficient ( egl) phenotype. Assay validation involved measuring chitinase release from wild-type C. elegans (N2 strain), sel-12 presenilin loss-of-function mutants, and 2 strains of C. elegans with mutations in the egl-36K+ channel gene. Failure to find specific presenilin inhibitors in this collection likely reflects the small number of compounds tested, rather than a flaw in screening strategy. Absent defined biochemical pathways for presenilin, this screening method, which takes advantage of the genetic system available in C. elegans and its historical use for anthelminthic screening, permits an entry into mechanism-based discovery of drugs for Alzheimer s disease. ( Journal of Biomolecular Screening 2004:147-152)

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Caenorhabditis elegans as a Model Organism to Evaluate the Antioxidant Effects of Phytochemicals

Molecules ◽

10.3390/molecules25143194 ◽

2020 ◽

Vol 25 (14) ◽

pp. 3194

Author(s):

Begoña Ayuda-Durán ◽

Susana González-Manzano ◽

Ana M. González-Paramás ◽

Celestino Santos-Buelga

Keyword(s):

Oxidative Stress ◽

Caenorhabditis Elegans ◽

Model Organism ◽

Lipid Peroxides ◽

Biological Research ◽

Loss Of Function ◽

Fluorescent Reporters ◽

C Elegans ◽

High Degree

The nematode Caenorhabditis elegans was introduced as a model organism in biological research by Sydney Brenner in the 1970s. Since then, it has been increasingly used for investigating processes such as ageing, oxidative stress, neurodegeneration, or inflammation, for which there is a high degree of homology between C. elegans and human pathways, so that the worm offers promising possibilities to study mechanisms of action and effects of phytochemicals of foods and plants. In this paper, the genes and pathways regulating oxidative stress in C. elegans are discussed, as well as the methodological approaches used for their evaluation in the worm. In particular, the following aspects are reviewed: the use of stress assays, determination of chemical and biochemical markers (e.g., ROS, carbonylated proteins, lipid peroxides or altered DNA), influence on gene expression and the employment of mutant worm strains, either carrying loss-of-function mutations or fluorescent reporters, such as the GFP.

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Tissue- and paralogue-specific functions of acyl-CoA-binding proteins in lipid metabolism in Caenorhabditis elegans

Biochemical Journal ◽

10.1042/bj20102099 ◽

2011 ◽

Vol 437 (2) ◽

pp. 231-241 ◽

Cited By ~ 26

Author(s):

Ida C. Elle ◽

Karina T. Simonsen ◽

Louise C. B. Olsen ◽

Pernille K. Birck ◽

Sidse Ehmsen ◽

...

Keyword(s):

Caenorhabditis Elegans ◽

Unsaturated Fatty Acids ◽

Expression Patterns ◽

High Specificity ◽

Tissue Expression ◽

Yeast Cells ◽

Loss Of Function ◽

C Elegans ◽

Eukaryotic Species ◽

Quadruple Mutant

ACBP (acyl-CoA-binding protein) is a small primarily cytosolic protein that binds acyl-CoA esters with high specificity and affinity. ACBP has been identified in all eukaryotic species, indicating that it performs a basal cellular function. However, differential tissue expression and the existence of several ACBP paralogues in many eukaryotic species indicate that these proteins serve distinct functions. The nematode Caenorhabditis elegans expresses seven ACBPs: four basal forms and three ACBP domain proteins. We find that each of these paralogues is capable of complementing the growth of ACBP-deficient yeast cells, and that they exhibit distinct temporal and tissue expression patterns in C. elegans. We have obtained loss-of-function mutants for six of these forms. All single mutants display relatively subtle phenotypes; however, we find that functional loss of ACBP-1 leads to reduced triacylglycerol (triglyceride) levels and aberrant lipid droplet morphology and number in the intestine. We also show that worms lacking ACBP-2 show a severe decrease in the β-oxidation of unsaturated fatty acids. A quadruple mutant, lacking all basal ACBPs, is slightly developmentally delayed, displays abnormal intestinal lipid storage, and increased β-oxidation. Collectively, the present results suggest that each of the ACBP paralogues serves a distinct function in C. elegans.

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Neuronal KGB-1 JNK MAPK signaling regulates the dauer developmental decision in response to environmental stress in C. elegans

10.1101/2021.06.28.450206 ◽

2021 ◽

Author(s):

Deepshikha Dogra ◽

Warakorn Kulalert ◽

Frank Schroeder ◽

Dennis H Kim

Keyword(s):

Elevated Temperature ◽

Signaling Pathways ◽

Mapk Pathway ◽

Negative Regulator ◽

Loss Of Function ◽

C Elegans ◽

Metabolic Remodeling ◽

Dauer Formation ◽

Identification And Characterization

In response to stressful growth conditions of high population density, food scarcity and elevated temperature, young larvae of nematode Caenorhabditis elegans can enter a developmentally arrested stage called dauer that is characterized by dramatic anatomic and metabolic remodeling. Genetic analysis of dauer formation of C. elegans has served as an experimental paradigm for the identification and characterization of conserved neuroendocrine signaling pathways. Here, we report the identification and characterization of a conserved JNK-like mitogen-activated protein kinase (MAPK) pathway that is required for dauer formation in response to environmental stressors. We observed that loss-of-function mutations in the MLK-1-MEK-1-KGB-1 MAPK pathway suppress dauer entry. Loss-of-function mutation in the VHP-1 MAPK phosphatase, a known negative regulator of KGB-1 signaling, results in constitutive dauer formation which is dependent on the presence of dauer pheromone but independent of diminished food levels or elevated temperatures. Our data suggest that KGB-1 pathway acts in the sensory neurons, in parallel to established insulin and TGF-β signaling pathways, to transduce the dauer-inducing environmental cues of diminished food levels and elevated temperature.

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Hypolipidaemia among patients with PMM2-CDG is associated with low circulating PCSK9 levels: a case report followed by observational and experimental studies

Journal of Medical Genetics ◽

10.1136/jmedgenet-2019-106102 ◽

2019 ◽

Vol 57 (1) ◽

pp. 11-17 ◽

Cited By ~ 3

Author(s):

Michael Chong ◽

Grace Yoon ◽

Delia Susan-Resiga ◽

Ann Chamberland ◽

David Cheillan ◽

...

Keyword(s):

Side Effects ◽

Experimental Studies ◽

Ldl Receptor ◽

Cerebellar Atrophy ◽

Density Lipoprotein ◽

Negative Regulator ◽

Global Developmental Delay ◽

Loss Of Function ◽

Pcsk9 Inhibitors

BackgroundProprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors are novel therapeutics for reducing low-density lipoprotein cholesterol (LDLc). While serious side-effects have not been observed in short-term clinical trials, there remain concerns that long-term PCSK9 inhibition may cause neurocognitive side-effects.Methods and resultsAn adult male with childhood-onset global developmental delay, cerebellar atrophy and severe hypolipidaemia underwent extensive biochemical and genetic investigations. Initial testing revealed low circulating PCSK9 levels and a common loss-of-function PCSK9 polymorphism, but these findings did not fully account for severe hypolipidaemia. Whole-exome sequencing was subsequently performed and identified two pathogenic phosphomannose mutase 2 (PMM2) variants (p.Arg141His and p.Pro69Ser) known to cause PMM2-associated congenital disorder of glycosylation (PMM2-CDG). A diagnosis of PMM2-CDG was consistent with the proband’s neurological symptoms and severe hypolipidaemia. Given that PMM2-CDG is characterised by defective protein N-glycosylation and that PCSK9 is a negative regulator of LDLc, we postulated that loss of PCSK9 N-glycosylation mediates hypolipidaemia among patients with PMM2-CDG. First, in an independent cohort of patients with PMM2-CDG (N=8), we verified that circulating PCSK9 levels were significantly lower in patients than controls (p=0.0006). Second, we conducted in vitro experiments in hepatocyte-derived cells to evaluate the effects of PCSK9 N-glycosylation loss on LDL receptor (LDLR) activity. Experimental results suggest that defective PCSK9 N-glycosylation reduces the ability of circulating PCSK9 to degrade LDLR.ConclusionLife-long exposure to genetically lower PCSK9 per se is unlikely to cause neurocognitive impairment. Both observational and experimental findings suggest that hypolipidaemia in PMM2-CDG may be partially mediated by loss of PCSK9 N-glycosylation and/or its regulators.

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