Analysis of C. elegans acetylcholine synthesis mutants reveals a temperature-sensitive requirement for cholinergic neuromuscular function

Genetics ◽  
2021 ◽  
Author(s):  
Janet S Duerr ◽  
John R McManus ◽  
John A Crowell ◽  
James B Rand
Keyword(s):  
Synaptic Vesicles ◽  
Neuromuscular Function ◽  
Temperature Sensitive ◽  
Temperature Dependent ◽  
Behavioral Deficits ◽  
Acetylcholine Synthesis ◽  
C Elegans ◽  
Protein Levels ◽  
Pumping Rates ◽  
Almost All

Abstract In Caenorhabditis elegans, the cha-1 gene encodes choline acetyltransferase (ChAT), the enzyme that synthesizes the neurotransmitter acetylcholine. We have analyzed a large number of cha-1 hypomorphic mutants, most of which are missense alleles. Some homozygous cha-1 mutants have approximately normal ChAT immunoreactivity; many other alleles lead to consistent reductions in synaptic immunostaining, although the residual protein appears to be stable. Regardless of protein levels, neuromuscular function of almost all mutants is temperature sensitive, i.e., neuromuscular function is worse at 25° than at 14°. We show that the temperature effects are not related to acetylcholine release, but specifically to alterations in acetylcholine synthesis. This is not a temperature-dependent developmental phenotype, because animals raised at 20° to young adulthood and then shifted for 2 hours to either 14° or 25° had swimming and pharyngeal pumping rates similar to animals grown and assayed at either 14° or 25°, respectively. We also show that the temperature-sensitive phenotypes are not limited to missense alleles; rather, they are a property of most or all severe cha-1 hypomorphs. We suggest that our data are consistent with a model of ChAT protein physically, but not covalently, associated with synaptic vesicles; and there is a temperature-dependent equilibrium between vesicle-associated and cytoplasmic (i.e., soluble) ChAT. Presumably, in severe cha-1 hypomorphs, increasing the temperature would promote dissociation of some of the mutant ChAT protein from synaptic vesicles, thus removing the site of acetylcholine synthesis (ChAT) from the site of vesicular acetylcholine transport. This, in turn, would decrease the rate and extent of vesicle-filling, thus increasing the severity of the behavioral deficits.

scholarly journals Loss of Aly/ALYREF Suppresses Toxicity in Both Tau and TDP-43 Models of Neurodegeneration

2021 ◽  
Author(s):  
Rebecca Kow ◽  
Aristide Black ◽  
Aleen Saxton ◽  
Nicole Liachko ◽  
Brian Kraemer
Keyword(s):  
Nuclear Export ◽  
Molecular Mechanisms ◽  
Rna Binding ◽  
Mrna Levels ◽  
Tau Pathology ◽  
Human Cell Culture ◽  
Behavioral Deficits ◽  
C Elegans ◽  
Protein Levels ◽  
Binding Protein Gene

Abstract Background Neurodegenerative diseases with tau pathology, or tauopathies, include Alzheimer’s Disease and related dementia disorders. Previous work has shown that loss of the poly(A) RNA-binding protein gene sut2/MSUT2 strongly suppressed tauopathy in C. elegans, human cell culture, and mouse models of tauopathy. However, the mechanism of suppression is still unclear. Recent work has shown that MSUT2 protein interacts with the THO complex and ALYREF, which are components of the mRNA nuclear export complex. Additionally, previous work showed ALYREF homolog Ref1 modulates TDP-43 and G 4 C 2 toxicity in D. melanogaster models. Methods We used transgenic C. elegans models of tau or TDP-43 toxicity to investigate the effects of loss of ALYREF function on tau and TDP-43 toxicity. In C. elegans, there are three genes that are homologous to human ALYREF: aly-1, aly-2, and aly-3. Results We found that loss of C. elegans aly gene function, especially loss of both aly-2 and aly-3, suppressed tau-induced toxic phenotypes. Loss of aly-2 and aly-3 was also able to suppress TDP-43-induced behavioral deficits. However, loss of aly-2 and aly-3 had divergent effects on mRNA and protein levels as total tau protein levels were reduced while mRNA levels were increased, but no significant effects were seen on total TDP-43 protein or mRNA levels. Conclusions Our results suggest that although aly genes modulate both tau and TDP-43-induced toxicity phenotypes, the molecular mechanisms of suppression are different and separated from impacts on mRNA and protein levels. Altogether this study highlights the importance of elucidating RNA-related mechanisms in both tau and TDP-43-induced toxicity.

scholarly journals Defects in mating behavior are the primary cause of sterility in C. elegans males at elevated temperature

2019 ◽  
Author(s):  
Emily M. Nett ◽  
Nicholas B. Sepulveda ◽  
Lisa N. Petrella
Keyword(s):  
Elevated Temperature ◽  
Mating Behavior ◽  
Male Fertility ◽  
Male Reproduction ◽  
Temperature Sensitive ◽  
Male Mating ◽  
Sperm Activation ◽  
Successful Mating ◽  
C Elegans ◽  
Almost All

AbstractReproduction is a fundamental imperative of all forms of life. For all the advantages sexual reproduction confers, it has a deeply conserved flaw: it is temperature sensitive. As temperatures rise, fertility decreases. Across species male fertility is particularly sensitive to elevated temperature. Previously we have shown in the model nematode worm C. elegans, that all males are fertile at 20°C but almost all males have lost fertility at 27°C. Male fertility is dependent on the production functional sperm, successful mating and transfer of sperm, and successful fertilization post-mating. To determine how male fertility is impacted by elevated temperature we analyzed these aspects of male reproduction at 27°C in three wild-type strains of C. elegans: JU1171, LKC34, and N2. We found no effect of elevated temperature on the number of immature non-motile spermatids formed. There was a weak effect of elevated temperature on sperm activation that may negatively impact sperm function. In stark contrast, there was a strong effect of elevated temperature on male mating behavior and sperm transfer such that males very rarely successfully completed mating when exposed to 27°C. Therefore, we propose a model where elevated temperature reduces male fertility due to the negative impacts of temperature on the somatic tissues necessary for mating. Loss of successful mating at elevated temperature overrides any effects that temperature may have on the germline or sperm cells.

scholarly journals Like wings of a bird: functional divergence and complementarity between HLA-A and HLA-B molecules

2020 ◽  
Author(s):  
Da Di ◽  
Jose Manuel Nunes ◽  
Wei Jiang ◽  
Alicia Sanchez-Mazas
Keyword(s):  
Balancing Selection ◽  
Functional Divergence ◽  
Peptide Binding ◽  
Human Leukocyte ◽  
Environmental Pressures ◽  
Protein Levels ◽  
Functional Complementarity ◽  
Vital Functions ◽  
Almost All ◽  
Immune Potential

Abstract Human leukocyte antigen (HLA) genes are among the most polymorphic of our genome, as a likely consequence of balancing selection related to their central role in adaptive immunity. HLA-A and HLA-B genes were recently suggested to evolve through a model of joint divergent asymmetric selection conferring all populations, including those with severe loss of diversity, an equivalent immune potential. However, the mechanisms by which these two genes might undergo joint evolution while displaying very distinct allelic profiles in populations worldwide are still unknown. To address this issue, we carried out extensive data analyses (among which factorial correspondence and linear modelling) on 2,909 common and rare HLA-A, HLA-B and HLA-C alleles and 200,000 simulated pathogenic peptides by taking into account sequence variation, predicted peptide-binding affinity and HLA allele frequencies in 123 populations worldwide. Our results show that HLA-A and HLA-B (but not HLA-C) molecules maintain considerable functional divergence in almost all populations, which likely plays an instrumental role in their immune defence. We also provide robust evidence of functional complementarity between HLA-A and HLA-B molecules, which display asymmetric relationships in terms of amino acid diversity at both inter- and intra-protein levels and in terms of promiscuous or fastidious peptide-binding specificities. Like two wings of a flying bird, the functional complementarity of HLA-A and HLA-B is a perfect example, in our genome, of duplicated genes sharing their capacity of assuming common vital functions while being submitted to complex and sometimes distinct environmental pressures.

scholarly journals Polymodal Functionality of C. elegans OLL Neurons in Mechanosensation and Thermosensation

2021 ◽  
Author(s):  
Yuedan Fan ◽  
Wenjuan Zou ◽  
Jia Liu ◽  
Umar Al-Sheikh ◽  
Hankui Cheng ◽  
...  
Keyword(s):  
Glutamate Receptor ◽  
Sensory Neurons ◽  
Molecular Mechanisms ◽  
Temperature Sensitive ◽  
Cold Sensation ◽  
Cold Response ◽  
C Elegans ◽  
Sensory Modalities ◽  
A Cell ◽  
Bona Fide

AbstractSensory modalities are important for survival but the molecular mechanisms remain challenging due to the polymodal functionality of sensory neurons. Here, we report the C. elegans outer labial lateral (OLL) sensilla sensory neurons respond to touch and cold. Mechanosensation of OLL neurons resulted in cell-autonomous mechanically-evoked Ca2+ transients and rapidly-adapting mechanoreceptor currents with a very short latency. Mechanotransduction of OLL neurons might be carried by a novel Na+ conductance channel, which is insensitive to amiloride. The bona fide mechano-gated Na+-selective degenerin/epithelial Na+ channels, TRP-4, TMC, and Piezo proteins are not involved in this mechanosensation. Interestingly, OLL neurons also mediated cold but not warm responses in a cell-autonomous manner. We further showed that the cold response of OLL neurons is not mediated by the cold receptor TRPA-1 or the temperature-sensitive glutamate receptor GLR-3. Thus, we propose the polymodal functionality of OLL neurons in mechanosensation and cold sensation.

The Expression of Sel1L and Tan-1 in Normal and Neoplastic Cells

2000 ◽  
Vol 15 (1) ◽  
pp. 26-32 ◽  
Author(s):  
M. Cattaneo ◽  
R. Orlandi ◽  
C. Ronchini ◽  
P. Granelli ◽  
G. Malferrari ◽  
...  
Keyword(s):  
Cell Function ◽  
Sequence Similarity ◽  
Expression Patterns ◽  
Negative Regulator ◽  
Chromosomal Mapping ◽  
Normal Adult ◽  
Neoplastic Cells ◽  
C Elegans ◽  
Pancreatic Cancers ◽  
Almost All

We have previously reported on the isolation and chromosomal mapping of a novel human gene (SEL1L), which shows sequence similarity to sel-1, an extragenic suppressor of C. elegans. sel-1 functions as a negative regulator of lin-12 activity, the latter being implicated in the control of diverse cellular differentiation events. In the present study we compare the expression patterns of SEL1L and TAN-1, the human ortholog of lin-12 in normal and neoplastic cells. We found that, whereas both genes are expressed in fetal tissues at similar levels, they are differentially expressed in normal adult and neoplastic cells. In normal adult cells SEL1L is generally present at very low levels; only in the cells of the pancreas does it show maximum expression. By contrast, SEL1L is generally well represented in most neoplastic cells but not in those of pancreatic and gastric carcinomas, where transcription is either downregulated or completely repressed. TAN-1 on the other hand is well represented in almost all normal and neoplastic cells, with very few exceptions. Our observations suggest that SEL1L is presumably implicated in pancreatic and gastric carcinogenesis and that, along with TAN-1, it is very important for normal cell function. Alterations in the expression of SEL1L may be used as a prognostic marker for gastric and pancreatic cancers.

Opponent vesicular transporters regulate the strength of glutamatergic neurotransmission in a C. elegans sensory circuit

2021 ◽  
Author(s):  
Jung-Hwan Choi ◽  
Lauren Bayer Horowitz ◽  
Niels Ringstad
Keyword(s):  
Synaptic Vesicles ◽  
Glutamate Release ◽  
Glutamate Transporter ◽  
Synaptic Function ◽  
Functional Coupling ◽  
Glutamate Signaling ◽  
C Elegans ◽  
Vesicular Transporters ◽  
Chemical Synapses

At chemical synapses, neurotransmitters are packaged into synaptic vesicles that release their contents in response to depolarization. Despite its central role in synaptic function, regulation of the machinery that loads vesicles with neurotransmitters remains poorly understood. We find that synaptic glutamate signaling in a C. elegans chemosensory circuit is regulated by antagonistic interactions between the canonical vesicular glutamate transporter EAT-4/VGLUT and another vesicular transporter, VST-1. Loss of VST-1 strongly potentiates glutamate release from chemosensory BAG neurons and disrupts chemotaxis behavior. Analysis of the circuitry downstream of BAG neurons shows that excess glutamate release disrupts behavior by inappropriately recruiting RIA interneurons to the BAG-associated chemotaxis circuit. Our data indicate that in vivo the strength of glutamatergic synapses is controlled by regulation of neurotransmitter packaging into synaptic vesicles via functional coupling of VGLUT and VST-1.

Synaptojanin family members are implicated in endocytic membrane traffic in yeast

1998 ◽  
Vol 111 (22) ◽  
pp. 3347-3356 ◽  
Author(s):  
B. Singer-Kruger ◽  
Y. Nemoto ◽  
L. Daniell ◽  
S. Ferro-Novick ◽  
P. De Camilli
Keyword(s):  
Synaptic Vesicles ◽  
Direct Evidence ◽  
Family Members ◽  
Fluid Phase ◽  
Growth Defect ◽  
Temperature Sensitive ◽  
Close Link ◽  
Fluid Phase Endocytosis ◽  
Synaptojanin 1

The synaptojanins represent a subfamily of inositol 5′-phosphatases that contain an NH2-terminal Sac1p homology domain. A nerve terminal-enriched synaptojanin, synaptojanin 1, was previously proposed to participate in the endocytosis of synaptic vesicles and actin function. The genome of Saccharomyces cerevisiae contains three synaptojanin-like genes (SJL1, SJL2 and SJL3), none of which is essential for growth. We report here that a yeast mutant lacking SJL1 and SJL2 (Deltasjl1 Deltasjl2) exhibits a severe defect in receptor-mediated and fluid-phase endocytosis. A less severe endocytic defect is present in a Deltasjl2 Deltasjl3 mutant, while endocytosis is normal in a Deltasjl1 Deltasjl3 mutant. None of the mutants are impaired in invertase secretion. The severity of the endocytic impairment of the sjl double mutants correlates with the severity of actin and polarity defects. Furthermore, the deletion of SJL1 suppresses the temperature-sensitive growth defect of sac6, a mutant in yeast fimbrin, supporting a role for synaptojanin family members in actin function. These findings provide a first direct evidence for a role of synaptojanin family members in endocytosis and provide further evidence for a close link between endocytosis and actin function.

scholarly journals Eukaryotic initiation factor EIF-3.G augments mRNA translation efficiency to regulate neuronal activity

2021 ◽  
Author(s):  
Stephen M Blazie ◽  
Seika Takayanagi-Kiya ◽  
Katherine A McCulloch ◽  
Yishi Jin
Keyword(s):  
Rna Binding ◽  
Mrna Translation ◽  
Initiation Factor ◽  
Translation Efficiency ◽  
Dependent Manner ◽  
Control Activity ◽  
C Elegans ◽  
Protein Levels ◽  
Neuronal Protein

AbstractThe translation initiation complex eIF3 imparts specialized functions to regulate protein expression. However, understanding of eIF3 activities in neurons remains limited despite widespread dysregulation of eIF3 subunits in neurological disorders. Here, we report a selective role of theC. elegansRNA-binding subunit EIF-3.G in shaping the neuronal protein landscape. We identify a missense mutation in the conserved Zinc-Finger (ZF) of EIF-3.G that acts in a gain-of-function manner to dampen neuronal hyperexcitation. Using neuron type-specific seCLIP, we systematically mapped EIF-3.G-mRNA interactions and identified EIF-3.G occupancy on GC-rich 5′UTRs of a select set of mRNAs enriched in activity-dependent functions. We demonstrate that the ZF mutation in EIF-3.G alters translation in a 5′UTR dependent manner. Our study reveals anin vivomechanism for eIF3 in governing neuronal protein levels to control activity states and offers insights into how eIF3 dysregulation contributes to neuronal disorders.

scholarly journals Crosstalk in oxygen homeostasis networks: SKN-1/NRF inhibits the HIF-1 hypoxia-inducible factor in Caenorhabditis elegans

2021 ◽  
Author(s):  
Dingxia Feng ◽  
Zhiwei Zhai ◽  
Zhiyong Shao ◽  
Yi Zhang ◽  
Jo Anne Powell-Coffman
Keyword(s):  
Oxidative Stress ◽  
Hypoxia Inducible Factor ◽  
Regulatory Sequences ◽  
Low Oxygen ◽  
Transcriptional Responses ◽  
C Elegans ◽  
Protein Levels ◽  
Oxygen Homeostasis ◽  
Genome Wide ◽  
A Genome

AbstractDuring development, homeostasis, and disease, organisms must balance responses that allow adaptation to low oxygen (hypoxia) with those that protect cells from oxidative stress. The evolutionarily conserved hypoxia-inducible factors are central to these processes, as they orchestrate transcriptional responses to oxygen deprivation. Here, we employ genetic strategies in C. elegans to identify stress-responsive genes and pathways that modulate the HIF-1 hypoxia-inducible factor and facilitate oxygen homeostasis. Through a genome-wide RNAi screen, we show that RNAi-mediated mitochondrial or proteasomal dysfunction increases the expression of hypoxia-responsive reporter Pnhr-57:GFP in C. elegans. Interestingly, only a subset of these effects requires hif-1. Of particular importance, we found that skn-1 RNAi increases the expression of hypoxia-responsive reporter Pnhr-57:GFP and elevates HIF-1 protein levels. The SKN-1/NRF transcription factor has been shown to promote oxidative stress resistance. We present evidence that the crosstalk between HIF-1 and SKN-1 is mediated by EGL-9, the prolyl hydroxylase that targets HIF-1 for oxygen-dependent degradation. Treatment that induces SKN-1, such as heat, increases expression of a Pegl-9:GFP reporter, and this effect requires skn-1 function and a putative SKN-1 binding site in egl-9 regulatory sequences. Collectively, these data support a model in which SKN-1 promotes egl-9 transcription, thereby inhibiting HIF-1. We propose that this interaction enables animals to adapt quickly to changes in cellular oxygenation and to better survive accompanying oxidative stress.

Sign in / Sign up

Export Citation Format

Share Document