Mutagenesis and Imaging Studies of BMP Signaling Mechanisms in C. elegans

SummaryAn organisms’ ability to adapt to heat can be key to its survival. Cells adapt to temperature shifts by adjusting lipid desaturation levels and the fluidity of membranes in a process that is thought to be controlled cell autonomously. We have discovered that subtle, step-wise increments in ambient temperature can lead to the conserved heat shock response being activated in head neurons of C. elegans. This response is exactly opposite to the expression of the lipid desaturase FAT-7 in the worm’s gut. We find that the over-expression of the master regulator of this response, Hsf-1, in head neurons, causes extensive fat remodeling to occur across tissues. These changes include a decrease in FAT-7 expression and a shift in the levels of unsaturated fatty acids in the plasma membrane. These shifts are in line with membrane fluidity requirements to survive in warmer temperatures. We have identified that the cGMP receptor, TAX-2/TAX-4, as well as TGF-β/BMP signaling, as key players in the transmission of neuronal stress to peripheral tissues. This is the first study to suggest that a thermostat-based mechanism can centrally coordinate membrane fluidity in response to warm temperatures across tissues in multicellular animals.

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A PINCH-1–Smurf1 signaling axis mediates mechano-regulation of BMPR2 and stem cell differentiation

The Journal of Cell Biology ◽

10.1083/jcb.201902022 ◽

2019 ◽

Vol 218 (11) ◽

pp. 3773-3794

Author(s):

Ling Guo ◽

Rong Wang ◽

Kuo Zhang ◽

Jifan Yuan ◽

Jiaxin Wang ◽

...

Keyword(s):

Stem Cell ◽

Stem Cell Differentiation ◽

Bmp Signaling ◽

Signaling Mechanism ◽

Ubiquitin Protein Ligase ◽

Signaling Mechanisms ◽

Morphogenetic Protein ◽

Signaling Axis ◽

Fate Decision

Mechano-environment plays multiple critical roles in the control of mesenchymal stem cell (MSC) fate decision, but the underlying signaling mechanisms remain undefined. We report here a signaling axis consisting of PINCH-1, SMAD specific E3 ubiquitin protein ligase 1 (Smurf1), and bone morphogenetic protein type 2 receptor (BMPR2) that links mechano-environment to MSC fate decision. PINCH-1 interacts with Smurf1, which inhibits the latter from interacting with BMPR2 and consequently suppresses BMPR2 degradation, resulting in augmented BMP signaling and MSC osteogenic differentiation (OD). Extracellular matrix (ECM) stiffening increases PINCH-1 level and consequently activates this signaling axis. Depletion of PINCH-1 blocks stiff ECM-induced BMP signaling and OD, whereas overexpression of PINCH-1 overrides signals from soft ECM and promotes OD. Finally, perturbation of either Smurf1 or BMPR2 expression is sufficient to block the effects of PINCH-1 on BMP signaling and MSC fate decision. Our findings delineate a key signaling mechanism through which mechano-environment controls BMPR2 level and MSC fate decision.

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C. elegans DAF-16/FOXO interacts with TGF-ß/BMP signaling to induce germline tumor formation via mTORC1 activation

PLoS Genetics ◽

10.1371/journal.pgen.1006801 ◽

2017 ◽

Vol 13 (5) ◽

pp. e1006801 ◽

Cited By ~ 12

Author(s):

Wenjing Qi ◽

Yijian Yan ◽

Dietmar Pfeifer ◽

Erika Donner v. Gromoff ◽

Yimin Wang ◽

...

Keyword(s):

Tumor Formation ◽

Bmp Signaling ◽

C Elegans ◽

Mtorc1 Activation

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An extrasynaptic GABAergic signal modulates a pattern of forward movement in Caenorhabditis elegans

eLife ◽

10.7554/elife.14197 ◽

2016 ◽

Vol 5 ◽

Cited By ~ 24

Author(s):

Yu Shen ◽

Quan Wen ◽

He Liu ◽

Connie Zhong ◽

Yuqi Qin ◽

...

Keyword(s):

Motor Neurons ◽

Activity Patterns ◽

Gain Control ◽

Metabotropic Receptors ◽

Forward Movement ◽

C Elegans ◽

A Value ◽

Signaling Mechanisms ◽

Optimal Efficiency ◽

Gabaergic Modulation

As a common neurotransmitter in the nervous system, γ-aminobutyric acid (GABA) modulates locomotory patterns in both vertebrates and invertebrates. However, the signaling mechanisms underlying the behavioral effects of GABAergic modulation are not completely understood. Here, we demonstrate that a GABAergic signal in C. elegans modulates the amplitude of undulatory head bending through extrasynaptic neurotransmission and conserved metabotropic receptors. We show that the GABAergic RME head motor neurons generate undulatory activity patterns that correlate with head bending and the activity of RME causally links with head bending amplitude. The undulatory activity of RME is regulated by a pair of cholinergic head motor neurons SMD, which facilitate head bending, and inhibits SMD to limit head bending. The extrasynaptic neurotransmission between SMD and RME provides a gain control system to set head bending amplitude to a value correlated with optimal efficiency of forward movement.

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Osmosensitive gene expression in C. elegans is regulated by conserved signaling mechanisms that control protein translation initiation

The FASEB Journal ◽

10.1096/fasebj.26.1_supplement.881.5 ◽

2012 ◽

Vol 26 (S1) ◽

Author(s):

Elaine Lee ◽

Kevin Strange

Keyword(s):

Gene Expression ◽

Translation Initiation ◽

Protein Translation ◽

C Elegans ◽

Signaling Mechanisms ◽

Control Protein

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Mechanism of Interaction of BMP and Insulin Signaling in C. elegans Development and Homeostasis

10.1101/777805 ◽

2019 ◽

Author(s):

James F. Clark ◽

Emma J. Ciccarelli ◽

Gehan Ranepura ◽

Muhammad S. Hasan ◽

Alicia Meléndez ◽

...

Keyword(s):

Bmp Signaling ◽

Lipid Homeostasis ◽

Signaling Crosstalk ◽

C Elegans ◽

Morphogenetic Protein ◽

Autophagy Induction ◽

Dauer Formation ◽

And Function ◽

Modes Of Interaction ◽

Molecular Components

AbstractA small number of peptide growth factor ligands are used repeatedly in development and homeostasis to drive programs of cell differentiation and function. Cells and tissues must integrate inputs from these diverse signals correctly, while failure to do so leads to pathology, reduced fitness, or death. Previous work using the nematode C. elegans identified an interaction between the bone morphogenetic protein (BMP) and insulin/IGF-1-like signaling (IIS) pathways in the regulation of lipid homeostasis. The molecular components required for this interaction, however, were not known. Here we report that INS-4, one of 40 insulin-like peptides (ILPs), is specifically regulated by BMP signaling to modulate fat accumulation. Furthermore, we find that the IIS transcription factor DAF-16/FoxO, but not SKN-1/Nrf, acts downstream of BMP signaling in lipid homeostasis. Interestingly, BMP activity alters sensitivity of these two transcription factors to IIS-promoted cytoplasmic retention in opposite ways. Finally, we probe the extent of BMP and IIS interactions by testing two additional IIS functions, dauer formation and autophagy induction. Coupled with our previous work and that of other groups, we conclude that BMP and IIS pathways have at least three modes of interaction: independent, epistatic, and antagonistic. The molecular interactions we identify provide new insight into mechanisms of signaling crosstalk and potential therapeutic targets for IIS-related pathologies such as diabetes and metabolic syndrome.

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Conditional immobilization for live imaging C. elegans using auxin-dependent protein depletion

10.1101/2021.05.25.445686 ◽

2021 ◽

Author(s):

Cori K. Cahoon ◽

Diana E. Libuda

Keyword(s):

Candidate Genes ◽

Fluorescent Proteins ◽

Model Organism ◽

Live Imaging ◽

Similar Amount ◽

Sexually Dimorphic ◽

Imaging Studies ◽

C Elegans ◽

Dependent Protein ◽

Living Organisms

The visualization of biological processes using fluorescent proteins and dyes in living organisms has enabled numerous scientific discoveries. The nematode Caenorhabditis elegans is a widely used model organism for live imaging studies since the transparent nature of the worm enables imaging of nearly all tissues within a whole, intact animal. While current techniques are optimized to enable the immobilization of hermaphrodite worms for live imaging, many of these approaches fail to successfully restrain the smaller male worms. To enable live imaging of worms of both sexes, we developed a new genetic, conditional immobilization tool that uses the auxin inducible degron (AID) system to immobilize both hermaphrodites and male worms for live imaging. Based on chromosome location, mutant phenotype, and predicted germline consequence, we identified and AID-tagged three candidate genes (unc-18, unc-104, and unc-52). Strains with these AID-tagged genes were placed on auxin and tested for mobility and germline defects. Among the candidate genes, auxin-mediated depletion of UNC-18 caused significant immobilization of both hermaphrodite and male worms that was also partially reversible upon removal from auxin. Notably, we found that male worms require a higher concentration of auxin for a similar amount of immobilization as hermaphrodites, thereby suggesting a potential sex-specific difference in auxin absorption and/or processing. In both males and hermaphrodites, depletion of UNC-18 did not largely alter fertility, germline progression, nor meiotic recombination. Finally, we demonstrate that this new genetic tool can successfully immobilize both sexes enabling live imaging studies of sexually dimorphic features in C. elegans.

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Conditional immobilization for live imaging C. elegans using auxin-dependent protein depletion

G3 Genes|Genome|Genetics ◽

10.1093/g3journal/jkab310 ◽

2021 ◽

Author(s):

Cori K Cahoon ◽

Diana E Libuda

Keyword(s):

Candidate Genes ◽

Fluorescent Proteins ◽

Model Organism ◽

Live Imaging ◽

Similar Amount ◽

Sexually Dimorphic ◽

Imaging Studies ◽

C Elegans ◽

Dependent Protein ◽

Living Organisms

Abstract The visualization of biological processes using fluorescent proteins and dyes in living organisms has enabled numerous scientific discoveries. The nematode Caenorhabditis elegans is a widely used model organism for live imaging studies since the transparent nature of the worm enables imaging of nearly all tissues within a whole, intact animal. While current techniques are optimized to enable the immobilization of hermaphrodite worms for live imaging, many of these approaches fail to successfully restrain the smaller male worms. To enable live imaging of worms of both sexes, we developed a new genetic, conditional immobilization tool that uses the auxin inducible degron (AID) system to immobilize both adult and larval hermaphrodite and male worms for live imaging. Based on chromosome location, mutant phenotype, and predicted germline consequence, we identified and AID-tagged three candidate genes (unc-18, unc-104, and unc-52). Strains with these AID-tagged genes were placed on auxin and tested for mobility and germline defects. Among the candidate genes, auxin-mediated depletion of UNC-18 caused significant immobilization of both hermaphrodite and male worms that was also partially reversible upon removal from auxin. Notably, we found that male worms require a higher concentration of auxin for a similar amount of immobilization as hermaphrodites, thereby suggesting a potential sex-specific difference in auxin absorption and/or processing. In both males and hermaphrodites, depletion of UNC-18 did not largely alter fertility, germline progression, nor meiotic recombination. Finally, we demonstrate that this new genetic tool can successfully immobilize both sexes enabling live imaging studies of sexually dimorphic features in C. elegans.

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The C. elegans SMOC-1 protein acts cell non-autonomously to promote bone morphogenetic protein signaling

10.1101/416669 ◽

2018 ◽

Author(s):

Melisa S. DeGroot ◽

Herong Shi ◽

Alice Eastman ◽

Alexandra N. McKillop ◽

Jun Liu

Keyword(s):

Body Size ◽

Bone Morphogenetic Protein ◽

Calcium Binding ◽

Binding Protein ◽

Calcium Binding Protein ◽

Bmp Signaling ◽

C Elegans ◽

Morphogenetic Protein ◽

Positive Modulator ◽

Bmp Pathway

ABSTRACTBone morphogenetic protein (BMP) signaling regulates many different developmental and homeostatic processes in metazoans. The BMP pathway is conserved in Caenorhabditis elegans, and is known to regulate body size and mesoderm development. We have identified the C. elegans smoc-1 (Secreted MOdular Calcium binding protein-1) gene as a new player in the BMP pathway. smoc-1(0) null mutants have a small body size, while overexpression of smoc-1 led to a long body size and increased expression of the RAD-SMAD BMP reporter, suggesting that SMOC-1 acts as a positive modulator of BMP signaling. Using double mutant analysis, we showed that SMOC-1 antagonizes the function of the glypican LON-2 and acts through the BMP ligand DBL-1 to regulate BMP signaling. Moreover, SMOC-1 appears to specifically regulate BMP signaling without significant involvement in a TGFβ-like pathway that regulates dauer development. We found that smoc-1 is expressed in multiple tissues, including cells of the pharynx, intestine, and posterior hypodermis, and that the expression of smoc-1 in the intestine is positively regulated by BMP signaling. We further established that SMOC-1 functions cell non-autonomously to regulate body size. Human SMOC1 and SMOC2 can each partially rescue the smoc-1(0) mutant phenotype, suggesting that SMOC-1’s function in modulating BMP signaling is evolutionarily conserved. Together, our findings highlight a conserved role of SMOC proteins in modulating BMP signaling in metazoans.ARTICLE SUMMARYBMP signaling is critical for development and homeostasis in metazoans, and is under tight regulation. We report the identification and characterization of a Secreted MOdular Calcium binding protein SMOC-1 as a positive modulator of BMP signaling in C. elegans. We established that SMOC-1 antagonizes the function of LON-2/glypican and acts through the DBL-1/BMP ligand to promote BMP signaling. We identified smoc-1-expressing cells, and demonstrated that SMOC-1 acts cell non-autonomously and in a positive feedback loop to regulate BMP signaling. We also provide evidence suggesting that the function of SMOC proteins in the BMP pathway is conserved from worms to humans.

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