Identification of a Novel Link between the Intermediate Filament Organizer IFO-1 and Cholesterol Metabolism in the Caenorhabditis elegans Intestine

The intestine is an organ essential to organismal nutrient absorption, metabolic control, barrier function and immunoprotection. The Caenorhabditis elegans intestine consists of 20 cells harboring a dense intermediate filament network positioned below the apical plasma membrane that forms a junction-anchored sheath around the intestinal lumen. This evolutionarily conserved arrangement provides mechanical and overall stress-protection, and it serves as an important model for deciphering the role of intestinal architecture in metazoan biology. We recently reported that the loss-of-function mutation of the intestinal intermediate filament organizer IFO-1 perturbs this architecture, leading to reduced body size and reproduction. Here, we demonstrate that the IFO-1 mutation dramatically affects cholesterol metabolism. Mutants showed an increased sensitivity to cholesterol depletion, reduced cholesterol uptake, and cholesterol transfer to the gonads, which is also observed in worms completely lacking an intermediate filament network. Accordingly, we found striking similarities to transcriptome and lipidome profiles of a nuclear hormone receptor (NHR)-8 mutant. NHR-8 is homologous to mammalian LXR (liver X receptor) that serves as a sterol sensor and transcriptional regulator of lipid metabolism. Remarkably, increasing exogenous cholesterol partially rescues the developmental retardation in IFO-1 mutants. Our results uncover a novel link of the intestinal intermediate filament cytoskeleton to cholesterol metabolism that contributes to compromised growth and reproduction.

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Mediator subunit MDT-15/MED15 and Nuclear Receptor HIZR-1/HNF4 cooperate to regulate toxic metal stress responses in Caenorhabditis elegans

10.1101/565739 ◽

2019 ◽

Author(s):

Naomi Shomer ◽

Alexandre Zacharie Kadhim ◽

Jennifer Margaret Grants ◽

Xuanjin Cheng ◽

Amy Fong-Yuk Poon ◽

...

Keyword(s):

Caenorhabditis Elegans ◽

Stress Responses ◽

Physiological Stress ◽

Toxic Metal ◽

Nuclear Hormone Receptor ◽

Egg Laying ◽

Metal Stress ◽

Loss Of Function ◽

Metal Detoxification ◽

Excess Zinc

AbstractZinc is essential for cellular functions as it is a catalytic and structural component of many proteins. In contrast, cadmium is not required in biological systems and is toxic. Zinc and cadmium levels are closely monitored and regulated as their excess causes cell stress. To maintain homeostasis, organisms induce metal detoxification gene programs through stress responsive transcriptional regulatory complexes. In Caenorhabditis elegans, the MDT-15 subunit of the evolutionarily conserved Mediator transcriptional coregulator is required to induce genes upon exposure to excess zinc and cadmium. However, the regulatory partners of MDT-15 in this response, its role in cellular and physiological stress adaptation, and the putative role mammalian for MED15 in the metal stress responses remain unknown. Here, we show that MDT-15 interacts physically and functionally with the Nuclear Hormone Receptor HIZR-1 to promote molecular, cellular, and organismal adaptation to excess metals. Using gain- and loss-of-function mutants and qPCR and reporter analysis, we find that mdt-15 and hizr-1 cooperate to induce zinc and cadmium responsive genes. Moreover, the two proteins interact physically in yeast-two-hybrid assays and this interaction is enhanced by the addition of zinc or cadmium, the former a known ligand of HIZR-1. Functionally, mdt-15 and hizr-1 mutants show defective storage of excess zinc in the gut, and at the organismal level, mdt-15 mutants are hypersensitive to zinc- and cadmium-induced reductions in egg-laying. Lastly, mammalian MDT-15 orthologs bind genomic regulatory regions of metallothionein and zinc transporter genes in a metal-stimulated fashion, and human MED15 is required to induce a metallothionein gene in lung adenocarcinoma cells exposed to cadmium. Collectively, our data show that mdt-15 and hizr-1 cooperate to regulate metal detoxification and zinc storage and that this mechanism appears to be at least partially conserved in mammals.

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A BMP homolog acts as a dose-dependent regulator of body size and male tail patterning in Caenorhabditis elegans

Development ◽

10.1242/dev.126.2.241 ◽

1999 ◽

Vol 126 (2) ◽

pp. 241-250 ◽

Cited By ~ 4

Author(s):

Y. Suzuki ◽

M.D. Yandell ◽

P.J. Roy ◽

S. Krishna ◽

C. Savage-Dunn ◽

...

Keyword(s):

Body Size ◽

Caenorhabditis Elegans ◽

Expression Pattern ◽

Genetic Interactions ◽

Loss Of Function ◽

Male Tail ◽

C Elegans ◽

Reduced Body ◽

Smad Signaling Pathway ◽

Dose Dependent

We cloned the dbl-1 gene, a C. elegans homolog of Drosophila decapentaplegic and vertebrate BMP genes. Loss-of-function mutations in dbl-1 cause markedly reduced body size and defective male copulatory structures. Conversely, dbl-1 overexpression causes markedly increased body size and partly complementary male tail phenotypes, indicating that DBL-1 acts as a dose-dependent regulator of these processes. Evidence from genetic interactions indicates that these effects are mediated by a Smad signaling pathway, for which DBL-1 is a previously unidentified ligand. Our study of the dbl-1 expression pattern suggests a role for neuronal cells in global size regulation as well as male tail patterning.

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A novel function for the MAP kinase SMA-5 in intestinal tube stability

Molecular Biology of the Cell ◽

10.1091/mbc.e16-02-0099 ◽

2016 ◽

Vol 27 (24) ◽

pp. 3855-3868 ◽

Cited By ~ 10

Author(s):

Florian Geisler ◽

Harald Gerhardus ◽

Katrin Carberry ◽

Wayne Davis ◽

Erik Jorgensen ◽

...

Keyword(s):

Map Kinase ◽

Intermediate Filaments ◽

Intermediate Filament ◽

Catalytic Domain ◽

Intestinal Tube ◽

Reduced Body ◽

Terminal Web ◽

And Function ◽

Filament Network

Intermediate filaments are major cytoskeletal components whose assembly into complex networks and isotype-specific functions are still largely unknown. Caenorhabditis elegans provides an excellent model system to study intermediate filament organization and function in vivo. Its intestinal intermediate filaments localize exclusively to the endotube, a circumferential sheet just below the actin-based terminal web. A genetic screen for defects in the organization of intermediate filaments identified a mutation in the catalytic domain of the MAP kinase 7 orthologue sma-5(kc1). In sma-5(kc1) mutants, pockets of lumen penetrate the cytoplasm of the intestinal cells. These membrane hernias increase over time without affecting epithelial integrity and polarity. A more pronounced phenotype was observed in the deletion allele sma-5( n678) and in intestine-specific sma-5(RNAi). Besides reduced body length, an increased time of development, reduced brood size, and reduced life span were observed in the mutants, indicating compromised food uptake. Ultrastructural analyses revealed that the luminal pockets include the subapical cytoskeleton and coincide with local thinning and gaps in the endotube that are often enlarged in other regions. Increased intermediate filament phosphorylation was detected by two-dimensional immunoblotting, suggesting that loss of SMA-5 function leads to reduced intestinal tube stability due to altered intermediate filament network phosphorylation.

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Oxysterol-binding-protein (OSBP)-related protein 4 binds25-hydroxycholesterol and interacts with vimentin intermediate filaments

Biochemical Journal ◽

10.1042/bj3610461 ◽

2002 ◽

Vol 361 (3) ◽

pp. 461-472 ◽

Cited By ~ 55

Author(s):

Cheng WANG ◽

Lellean JeBAILEY ◽

Neale D. RIDGWAY

Keyword(s):

Intermediate Filaments ◽

Intermediate Filament ◽

Cellular Localization ◽

Cholesterol Metabolism ◽

Binding Protein ◽

Cholesterol Transport ◽

Ph Domain ◽

Transport Pathway ◽

Oxysterol Binding Protein ◽

Filament Network

Oxysterol-binding protein (OSBP) is the prototypical member of a class of phospholipid and oxysterol-binding proteins that interacts with the Golgi apparatus and regulates lipid and cholesterol metabolism. As a result of recent sequencing efforts, eleven other OSBP-related proteins (ORPs) have been identified in humans. We have investigated the structure, oxysterol-binding activity, cellular localization and function of ORP4 (also designated OSBP2 or HLM), a homologue that shares the highest degree of similarity with OSBP. Two ORP4 cDNAs were identified: a full-length ORP4 containing a pleckstrin homology (PH) domain and an oxysterol-binding region (designated ORP4-L), and a splice variant in which the PH domain and part of the oxysterol-binding domain were deleted (designated ORP4-S). ORP4 mRNA and protein expression overlapped partially with OSBP and were restricted to brain, heart, muscle and kidney. Like OSBP, ORP4-L bound [3H]25-hydroxycholesterol with high affinity and specificity. In contrast, ORP4-S did not bind [3H]25-hydroxycholesterol or [3H]7-ketocholesterol. Immunofluorescence localization in stably transfected Chinese hamster ovary cells showed that ORP4-S co-localized with vimentin and caused the intermediate filament network to bundle or aggregate. ORP4-L displayed a diffuse staining pattern that did not overlap with vimentin except when the microtubule network was disrupted with nocodazole. Oxysterols had no effect on the localization of either ORP4. Cells overexpressing ORP4-S had a 40% reduction in the esterification of low-density-lipoprotein-derived cholesterol, demonstrating that ORP4 interaction with intermediate filaments inhibits an intracellular cholesterol-transport pathway mediated by vimentin. These studies elucidate a hitherto unknown relationship between OSBPs and the intermediate filament network that influences cholesterol transport.

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Faculty Opinions recommendation of Assembling an intermediate filament network by dynamic cotranslation.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1033637.388861 ◽

2006 ◽

Author(s):

Kathleen J Green

Keyword(s):

Intermediate Filament ◽

Filament Network

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par-4, a gene required for cytoplasmic localization and determination of specific cell types in Caenorhabditis elegans embryogenesis.

Genetics ◽

10.1093/genetics/130.4.771 ◽

1992 ◽

Vol 130 (4) ◽

pp. 771-790 ◽

Cited By ~ 5

Author(s):

D G Morton ◽

J M Roos ◽

K J Kemphues

Keyword(s):

Caenorhabditis Elegans ◽

Cell Types ◽

Intestinal Cells ◽

Specific Cell ◽

Cytoplasmic Localization ◽

Loss Of Function ◽

Embryo Viability ◽

Cell Stage ◽

Maternal Genome

Abstract Specification of some cell fates in the early Caenorhabditis elegans embryo is mediated by cytoplasmic localization under control of the maternal genome. Using nine newly isolated mutations, and two existing mutations, we have analyzed the role of the maternally expressed gene par-4 in cytoplasmic localization. We recovered seven new par-4 alleles in screens for maternal effect lethal mutations that result in failure to differentiate intestinal cells. Two additional par-4 mutations were identified in noncomplementation screens using strains with a high frequency of transposon mobility. All 11 mutations cause defects early in development of embryos produced by homozygous mutant mothers. Analysis with a deficiency in the region indicates that it33 is a strong loss-of-function mutation. par-4(it33) terminal stage embryos contain many cells, but show no morphogenesis, and are lacking intestinal cells. Temperature shifts with the it57ts allele suggest that the critical period for both intestinal differentiation and embryo viability begins during oogenesis, about 1.5 hr before fertilization, and ends before the four-cell stage. We propose that the primary function of the par-4 gene is to act as part of a maternally encoded system for cytoplasmic localization in the first cell cycle, with par-4 playing a particularly important role in the determination of intestine. Analysis of a par-4; par-2 double mutant suggests that par-4 and par-2 gene products interact in this system.

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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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