Liesbet Temmerman

KU Leuven | ku leuven · Department of Biology

Neuropeptides are ancient signaling molecules in animals but only few peptide receptors are known outside bilaterians. Cnidarians possess a large number of G protein-coupled receptors (GPCRs) – the most common receptors of bilaterian neuropeptides – but most of these remain orphan with no known ligands. We searched for neuropeptides in the sea anem...

Neuropeptides are ancient signaling molecules in animals but only few peptide receptors are known outside bilaterians. Cnidarians possess a large number of G protein-coupled receptors (GPCRs) – the most common receptors of bilaterian neuropeptides – but most of these remain orphan with no known ligands. We searched for neuropeptides in the sea anem...

Entomopathogenic nematodes, including Steinernema spp., play an increasingly important role as biological alternatives to chemical pesticides. The infective juveniles of these worms use nictation-a behavior in which animals stand on their tails-as a host-seeking strategy. The developmentally-equivalent dauer larvae of the free-living nematode Caeno...

Neuropeptides are ancient signaling molecules in animals but only few peptide receptors are known outside bilaterians. Cnidarians possess a large number of G protein-coupled receptors (GPCRs), the most common receptors of bilaterian neuropeptides, but most of these remain orphan with no known ligands. We searched for neuropeptides in the sea anemon...

A rather peculiar but very potent means of achieving longevity is through axenic dietary restriction (ADR), where animals feed on (semi-)defined culture medium in absence of any other lifeform. The little knowledge we already have on ADR is mainly derived from studies using the model organism Caenorhabditis elegans, where ADR more than doubles orga...

Cryopreservation allows strains to be stored, eliminating genetic drift and maintenance costs. Existing cryopreservation methods for the economically-important entomopathogenic nematode Steinernema carpocapsae involve multiple incubation and filtration steps to precondition the animals. The standard protocol for freezing the model organism Caenorha...

Oviparous animals support reproduction via the incorporation of yolk as a nutrient source into the eggs. In Caenorhabditis elegans, however, yolk proteins seem dispensable for fecundity, despite constituting the vast majority of the embryonic protein pool and acting as carriers for nutrient-rich lipids. Here, we used yolk protein-deprived C. elegan...

Entomopathogenic nematodes including Steinernema spp. play an increasingly important role as biological alternatives to chemical pesticides. The infective juveniles of these worms use nictation - a behavior in which animals stand on their tails - as a host-seeking strategy. The developmentally-equivalent dauer larvae of the free-living nematode Cae...

Understanding how we can age healthily is a challenge at the heart of biogerontological interest. Whereas myriad genes are known to affect the lifespan of model organisms, effects of such interventions on healthspan—the period of life where an animal is considered healthy, rather than merely alive—are less clear. To understand relationships between...

As opposed to standard culturing, growing large numbers of C. elegans worms on Nematode Growth Medium-based RNA interference (RNAi) plates requires multiple transferring steps to prevent starvation, which increase handling time and reduce practical efficiency. We here provide an optimized method to grow four times more worms in RNAi conditions, thu...

Neuropeptides regulate animal physiology and behavior, making them widely studied targets of functional genetics research. While the field often relies on differential -omics approaches to build hypotheses, no such method exists for neuropeptidomics. It would nonetheless be valuable for studying behaviors suspected to be regulated by neuropeptides,...

Overlapping genes are widely prevalent, however, their expression and consequences are poorly understood. Here, we describe and functionally characterize a novel zyx-1 overlapping gene, azyx-1, with distinct regulatory functions in C. elegans. We observed conservation of alternative open reading frames overlapping the 5' region of zyxin family memb...

To find drivers of healthy ageing, a genome-wide association study (GWAS) was performed in healthy and unhealthy older individuals. Healthy individuals were defined as free from cardiovascular disease, stroke, heart failure, major adverse cardiovascular event, diabetes, dementia, cancer, chronic obstructive pulmonary disease (COPD), asthma, rheumat...

The Q system allows for conditional gene expression in several organisms, including C. elegans. We aimed to apply this system in C. elegans neurons to obtain temporally-resolved, tissue-specific expression of a fluorescent reporter. We report that, in our hands, there is undesired expression of the reporter in conditions where expression is suppose...

Transcriptome and ribosome sequencing have revealed the existence of many non-canonical transcripts, mainly containing splice variants, ncRNA, sORFs and altORFs. However, identification and characterization of products that may be translated out of these remains a challenge. Addressing this, we here report on 552 non-canonical proteins and splice v...

A mechanistic understanding of biology requires appreciating spatiotemporal aspects of gene expression and its functional implications. Conditional expression allows for (ir)reversibly switching genes on or off, with the potential of spatial and/or temporal control. This provides a valuable complement to the more often used constitutive gene (in)ac...

Transcription factors govern many of the time-and tissue-specific gene expression events in living organisms. CEH-60, a homolog of the TALE transcription factor PBX in vertebrates, was recently characterized as a new regulator of intestinal lipid mobilization in Caenorhabdi-tis elegans. Because CEH-60's orthologs and paralogs exhibit several other...

Background: Although several studies demonstrate prion-like properties of Tau fibrils, the effect of size in the seeding capacity of these aggregates is not fully understood. The aim of this study is to characterize Tau seeds by their size and seeding capacity. Methods: Tau aggregates were isolated from postmortem AD brain tissue and separated f...

Sleep and wakefulness are fundamental behavioral states of which the underlying molecular principles are becoming slowly elucidated. Transitions between these states require the coordination of multiple neurochemical and modulatory systems. In Caenorhabditis elegans sleep occurs during a larval transition stage called lethargus and is induced by so...

Getting a grip on how we may age healthily is a central interest of biogerontological research. To this end, a number of academic teams developed platforms for life- and healthspan assessment in Caenorhabditis elegans. These are very appealing for medium- to high throughput screens, but a broader implementation is lacking due to many systems relyin...

The onset of sexual maturity involves dramatic changes in physiology and gene expression in many animals. These include abundant yolk protein production in egg-laying species, an energetically costly process under extensive transcriptional control. Here, we used the model organism Caenorhabditis elegans to provide evidence for the spatiotemporally...

Metformin is the first-line therapy for treating type 2 diabetes and a promising anti-aging drug. We set out to address the fundamental question of how gut microbes and nutrition, key regulators of host physiology, affect the effects of metformin. Combining two tractable genetic models, the bacterium E. coli and the nematode C. elegans, we develope...

Numerous neuropeptide systems have been implicated to coordinately control energy homeostasis, both centrally and peripherally. However, the vertebrate neuropeptide Y (NPY) system has emerged as the best described one regarding this biological process. The protostomian ortholog of NPY is neuropeptide F, characterized by an RXRF(Y)amide carboxytermi...

Introduction: Neuropeptides are neuro-endocrine signaling molecules capable of signaling as neurotransmitters, neuromodulators or neurohormones. Studying how neuropeptide signaling is integrated in endocrine signaling pathways and how neuropeptides regulate endogenous processes is crucial to understanding how multicellular organisms respond to envi...

As demonstrated in various animal models, organismal longevity can be achieved via interventions that at the mechanistic level could be considered to entail ‘defensive’ responses: most long-lived mutants focus on somatic maintenance, while reducing growth pathway signalling and protein translation and turnover. We here provide evidence that the opp...

Antioxidants were long predicted to have lifespan-promoting effects, but in general this prediction has not been well supported. While some antioxidants do seem to have a clear effect on longevity, this may not be primarily as a result of their role in the removal of reactive oxygen species, but rather mediated by other mechanisms such as the modul...

Neuropeptides constitute a vast and functionally diverse family of neurochemical signaling molecules, and are widely involved in the regulation of various physiological processes. The nematode C. elegans is well-suited for the study of neuropeptide biochemistry and function, as neuropeptide biosynthesis enzymes are not essential for C. elegans viab...

BackgroundA series of human diseases are caused by the misfolding and aggregation of specific proteins or peptides into amyloid fibrils; nine of these diseases, referred to as polyglutamine diseases, are associated with proteins carrying an expanded polyglutamine (polyQ) region. While the presence of this latter is thought to be the determinant fac...

In C. elegans research, transcriptional activation of glutathione S-transferase 4 (gst-4) is often used as a read-out for SKN-1 activity. While many heed an assumed non-exclusivity of the GFP reporter signal driven by the gst-4 promoter to SKN-1, this is also often ignored. We here show that gst-4 can also be transcriptionally activated by EOR-1, a...

Human longevity continues to increase world-wide, often accompanied by decreasing birth rates. As a larger fraction of the population thus gets older, the number of people suffering from disease or disability increases dramatically, presenting a major societal challenge. Healthy ageing has therefore been selected by EU policy makers as an important...

Vitellogenesis or maternal yolk formation is considered critical to the reproduction of egg-laying animals. In invertebrates, however, most of its regulatory genes are still unknown. Via a combined mapping and whole-genome sequencing strategy, we performed a forward genetic screen to isolate novel regulators of yolk production in the nematode model...

For more than 20 years, reverse pharmacology has been the preeminent strategy to discover the activating ligands of orphan G protein-coupled receptors (GPCRs). The onset of a reverse pharmacology assay is the cloning and subsequent transfection of a GPCR of interest in a cellular expression system. The heterologous expressed receptor is then challe...

Significance Recently it has been suggested that metformin, the most commonly used antidiabetic drug, might also possess general health-promoting properties. Elucidating metformin’s mode of action will vastly increase its application range and will contribute to healthy aging. We reveal a signaling cascade in which metformin is able to extend lifes...

Bioactive peptides are present in all metazoan species where they orchestrate diverse functions. In the last decade, high-throughput approaches based on mass spectrometry helped the identification of endogenously occurring peptides in different species. We here review biochemical strategies to obtain sequence information of natural (non-tryptic) pe...

Neuropeptidergic signaling is widely adopted by animals for the regulation of physiology and behavior in a rapidly changing environment. The vasopressin/oxytocin neuropeptide family originates from an ancestral peptide precursor in the antecedent of protostomian and deuterostomian animals. In vertebrates, vasopressin and oxytocin have both hormonal...

Like most organisms, the nematode Caenorhabditis elegans relies heavily on neuropeptidergic signaling. This tiny animal represents a suitable model system to study neuropeptidergic signaling networks with single cell resolution due to the availability of powerful molecular and genetic tools. The availability of the worm's complete genome sequence a...

Social Neuropeptides in Nematodes The neuropeptides oxytocin and vasopressin stimulate maternal, reproductive, aggressive, and affiliative behaviors in mammals. They are implicated in behaviors ranging from ewe-lamb bonding in sheep to pair bonding in voles (see the Perspective by Emmons ). Now, Garrison et al. (p. 540 ) and Beets et al. (p. 543 )...

In Caenorhabditis elegans, pdfr-1 encodes three receptors of the secretin receptor family. These G protein-coupled receptors are activated by three neuropeptides, pigment dispersing factors 1a, 1b and 2, which are encoded by pdf-1 and pdf-2. We isolated a PDF receptor loss-of-function allele (lst34) by means of a mutagenesis screen and show that th...

Hyperglycemia causes diabetic nephropathy, a condition for which there are no specific diagnostic markers thatpredict progression to renal failure. Here we describe a multiplatform metabolomic analysis of urine from individualswith type 2 diabetes, collected before and immediately following experimental hyperglycemia. We used targetednuclear magnet...

The elucidation of the whole genome of the nematode Caenorhabditis elegans allowed for the identification of ortholog genes belonging to the pigment dispersing hormone/factor (PDH/PDF) peptide family. Members of this peptide family are known from crustaceans, insects and nematodes and seem to exist exclusively in ecdysozoans where they play a role...

Many of the diverse functions of neuropeptides are still elusive. As they are ideally suited to modulate traditional signaling, their added actions are not always detectable under standard laboratory conditions. The search for function assignment to peptide encoding genes can therefore greatly benefit from molecular information. Specific molecular...

Gonadotropin-releasing hormone (GnRH) is a critical and central hormone that regulates vertebrate reproduction. The high conservation of GnRH signaling within the chordates (deuterostomians) raises the important question as to whether its appearance might date back prior to the divergence of protostomian and deuterostomian lineages, about 700 milli...

As a consequence of the Earth's axial rotation, organisms display daily recurring rhythms in behavior and biochemical properties, such as hormone titers. The neuronal system controlling such changes is best studied in the fruit fly Drosophila melanogaster. In the nematode worm Caenorhabditis elegans, most homologs of these genes function in the het...

During recent decades, several research teams engaged in unraveling the molecular structure and the physiological significance of pigment dispersing hormone-like peptides, particularly with respect to colour change and biological rhythms. In this review, we first summarise the entire history of pigment dispersing hormone-like peptide research, thus...

Despite the general knowledge and repeated predictions of peptide G protein-coupled receptors following the elucidation of the Caenorhabditis elegans genome in 1998, only a few have been deorphanized so far. This was attributed to the apparent lack of coevolution between (neuro)peptides and their cognate receptors. To resolve this issue, we have us...

Protein identifications (Table 2). List of identified proteins that are differentially expressed 1 h, 4 h, 8 h and/or 24 h after infection with S. aureus. Proteins in bold were also identified after infection with the gram-negative bacterium Aeromonas hydrophila (Bogaerts et al. 2010, ref 29). Protein names in italic represent the human orthologues...

Comparison table (Table 3). Summary of proteins which are found differentially expressed upon challenge with both S. aureus (this paper) and A. hydrophila (Bogaerts et. al 2010, ref 29). "+" is up- and "-" is downregulated at least at one time point of the experiment. Proteins in red show an opposite pattern between the two conditions.

The striking similarities between the innate defences of vertebrates and invertebrates as well as the amenability of Caenorhabditis elegans for genetic analysis, have made this free-living ground nematode a popular model system in the study of bacterial pathogenesis. Although genetic studies have brought new insights, showing the inducibility and p...

The success of invertebrates throughout evolution is an excellent illustration of the efficiency of their defence strategies. Caenorhabditis elegans has proven to be an appropriate model for transcriptome studies of host-pathogen interactions. The aim of this paper is to complement this knowledge by investigating the worm's response to a Staphyloco...

The neuropeptides pigment dispersing factor (PDF) and vasoactive intestinal peptide (VIP) are known as key players in the circadian clock system of insects and mammals, respectively. In this study, we report the discovery and characterization of a widely conserved PDF-like neuropeptide precursor pathway in nematodes. Using a combinatorial approach...

This study addresses the biological function of CG18594, a Drosophila melanogaster phosphatidylethanolamine-binding protein (PEBP) that we named PEBP1, by combining fly genetics, survival experiments and differential proteomics. We demonstrate that transgenic flies overexpressing PEBP1 are highly protected against bacterial infection due to the rel...

Sequences of the 7 Schistocerca gregaria housekeeping genes. The sequences of the identified housekeeping genes are provided in this document. The primer sequences are highlighted in black.

Raw data of the real time PCRs. The data provided represent the calculated average CT values of the locust L5 and adult brain samples. In addition, the data for both developmental conditions are represented in a graph.

Neuromedin U (NMU) in vertebrates is a structurally highly conserved neuropeptide of which highest levels are found in the pituitary and gastrointestinal tract. In Drosophila, two neuropeptide genes encoding pyrokinins (PKs), capability (capa) and hugin, are possible insect homologs of vertebrate NMU. Here, the ligand for an orphan G protein-couple...

To obtain reliable quantitative RT-PCR data, normalization relative to stable housekeeping genes is required. However, in practice, expression levels of 'typical' housekeeping genes have been found to vary between tissues and under different experimental conditions. To date, validation studies of reference genes in insects are extremely rare and ha...

Members of the cholecystokinin (CCK)/gastrin family of peptides, including the arthropod sulfakinins, and their cognate receptors, play an important role in the regulation of feeding behavior and energy homeostasis. Despite many efforts after the discovery of CCK/gastrin immunoreactivity in nematodes 23 yr ago, the identity of these nematode CCK/ga...