The C. elegans peroxidasin PXN-2 is essential for embryonic morphogenesis and inhibits adult axon regeneration

Injured axons must regenerate to restore nervous system function, and regeneration is regulated in part by external factors from non-neuronal tissues. Many of these extrinsic factors act in the immediate cellular environment of the axon to promote or restrict regeneration, but the existence of long-distance signals regulating axon regeneration has not been clear. Here we show that the Rab GTPase rab-27 inhibits regeneration of GABAergic motor neurons in C. elegans through activity in the intestine. Re-expression of RAB-27, but not the closely related RAB-3, in the intestine of rab-27 mutant animals is sufficient to rescue normal regeneration. Several additional components of an intestinal neuropeptide secretion pathway also inhibit axon regeneration, including NPDC1/cab-1, SNAP25/aex-4, KPC3/aex-5, and the neuropeptide NLP-40, and re-expression of these genes in the intestine of mutant animals is sufficient to restore normal regeneration success. Additionally, NPDC1/cab-1 and SNAP25/aex-4 genetically interact with rab-27 in the context of axon regeneration inhibition. Together these data indicate that RAB-27-dependent neuropeptide secretion from the intestine inhibits axon regeneration, and point to distal tissues as potent extrinsic regulators of regeneration.

Download Full-text

CELF RNA binding proteins promote axon regeneration in C. elegans and mammals through alternative splicing of Syntaxins

eLife ◽

10.7554/elife.16072 ◽

2016 ◽

Vol 5 ◽

Cited By ~ 13

Author(s):

Lizhen Chen ◽

Zhijie Liu ◽

Bing Zhou ◽

Chaoliang Wei ◽

Yu Zhou ◽

...

Keyword(s):

Gene Expression ◽

Transcriptional Regulation ◽

Alternative Splicing ◽

Binding Proteins ◽

Rna Binding ◽

Axon Regeneration ◽

Rna Binding Proteins ◽

Mrna Isoforms ◽

C Elegans ◽

Mrna Targets

Axon injury triggers dramatic changes in gene expression. While transcriptional regulation of injury-induced gene expression is widely studied, less is known about the roles of RNA binding proteins (RBPs) in post-transcriptional regulation during axon regeneration. In C. elegans the CELF (CUGBP and Etr-3 Like Factor) family RBP UNC-75 is required for axon regeneration. Using crosslinking immunoprecipitation coupled with deep sequencing (CLIP-seq) we identify a set of genes involved in synaptic transmission as mRNA targets of UNC-75. In particular, we show that UNC-75 regulates alternative splicing of two mRNA isoforms of the SNARE Syntaxin/unc-64. In C. elegans mutants lacking unc-75 or its targets, regenerating axons form growth cones, yet are deficient in extension. Extending these findings to mammalian axon regeneration, we show that mouse Celf2 expression is upregulated after peripheral nerve injury and that Celf2 mutant mice are defective in axon regeneration. Further, mRNAs for several Syntaxins show CELF2 dependent regulation. Our data delineate a post-transcriptional regulatory pathway with a conserved role in regenerative axon extension.

Download Full-text

Effects of NAD+ in Caenorhabditis elegans Models of Neuronal Damage

Biomolecules ◽

10.3390/biom10070993 ◽

2020 ◽

Vol 10 (7) ◽

pp. 993

Author(s):

Yuri Lee ◽

Hyeseon Jeong ◽

Kyung Hwan Park ◽

Kyung Won Kim

Keyword(s):

Caenorhabditis Elegans ◽

Therapeutic Strategy ◽

Axon Regeneration ◽

Neuronal Damage ◽

Biological Processes ◽

Nematode Caenorhabditis Elegans ◽

C Elegans ◽

Neuronal Functions ◽

Molecular Components

Nicotinamide adenine dinucleotide (NAD+) is an essential cofactor that mediates numerous biological processes in all living cells. Multiple NAD+ biosynthetic enzymes and NAD+-consuming enzymes are involved in neuroprotection and axon regeneration. The nematode Caenorhabditis elegans has served as a model to study the neuronal role of NAD+ because many molecular components regulating NAD+ are highly conserved. This review focuses on recent findings using C. elegans models of neuronal damage pertaining to the neuronal functions of NAD+ and its precursors, including a neuroprotective role against excitotoxicity and axon degeneration as well as an inhibitory role in axon regeneration. The regulation of NAD+ levels could be a promising therapeutic strategy to counter many neurodegenerative diseases, as well as neurotoxin-induced and traumatic neuronal damage.

Download Full-text

Squeezing an Egg into a Worm: C. elegans Embryonic Morphogenesis

The Scientific World JOURNAL ◽

10.1100/tsw.2003.123 ◽

2003 ◽

Vol 3 ◽

pp. 1370-1381 ◽

Cited By ~ 11

Author(s):

A. J. Piekny ◽

P. E. Mains

Keyword(s):

Caenorhabditis Elegans ◽

Epidermal Cells ◽

Ventral Midline ◽

Single Row ◽

C Elegans ◽

Epithelial Sheet ◽

Embryonic Morphogenesis ◽

Shape Changes

We review key morphogenetic events that occur during Caenorhabditis elegans (www.wormbase.org/) embryogenesis. Morphogenesis transforms tissues from one shape into another through cell migrations and shape changes, often utilizing highly conserved actin-based contractile systems. Three major morphogenetic events occur during C. elegans embryogenesis: (1) dorsal intercalation, during which two rows of dorsal epidermal cells intercalate to form a single row; (2) ventral enclosure, where the dorsally located sheet of epidermal cells stretches to the ventral midline, encasing the embryo within a single epithelial sheet; and (3) elongation, during which actin-mediated contractions within the epithelial sheet lengthens the embryo. Here, we describe the known molecular players involved in each of these processes.

Download Full-text

Functional Dissection of C. elegans bZip-Protein CEBP-1 Reveals Novel Structural Motifs Required for Axon Regeneration and Nuclear Import

Frontiers in Cellular Neuroscience ◽

10.3389/fncel.2019.00348 ◽

2019 ◽

Vol 13 ◽

Author(s):

Rose Aria Malinow ◽

Phoenix Ying ◽

Thijs Koorman ◽

Mike Boxem ◽

Yishi Jin ◽

...

Keyword(s):

Nuclear Import ◽

Axon Regeneration ◽

Structural Motifs ◽

Bzip Protein ◽

C Elegans

Download Full-text

Axon regeneration mechanisms: insights from C. elegans

Trends in Cell Biology ◽

10.1016/j.tcb.2011.08.003 ◽

2011 ◽

Vol 21 (10) ◽

pp. 577-584 ◽

Cited By ~ 24

Author(s):

Lizhen Chen ◽

Andrew D. Chisholm

Keyword(s):

Axon Regeneration ◽

C Elegans

Download Full-text

The RhoGAP myosin 9/HUM-7 integrates membrane signals to modulate Rho/RHO-1 during embryonic morphogenesis in C. elegans

10.1101/325274 ◽

2018 ◽

Cited By ~ 1

Author(s):

Andre G. Wallace ◽

Hamidah Raduwan ◽

John Carlet ◽

Martha C. Soto

Keyword(s):

Plasma Membrane ◽

Epidermal Cell ◽

Rho Gtpase ◽

Actin Dynamics ◽

Rac Gtpase ◽

Cell Behaviors ◽

C Elegans ◽

Embryonic Morphogenesis

AbstractDuring embryonic morphogenesis, cells and tissues undergo dramatic movements under the control of F-actin regulators. Our studies of epidermal cell migrations in developing C. elegans embryos have identified multiple plasma membrane signals that regulate the Rac GTPase, thus regulating WAVE and Arp2/3 complexes, to promote branched F-actin formation and polarized enrichment. We describe here a pathway that acts in parallel to Rac to transduce membrane signals to control epidermal F-actin through the GTPase Rho. Rho contributes to epidermal migrations through effects on underlying neuroblasts. Here we identify signals to regulate Rho in the epidermis. HUM-7, the C. elegans homolog of human Myo9A and Myo9B, regulates F-actin dynamics during epidermal migrations, by controlling Rho. Genetics and biochemistry support that HUM-7 behaves as GAP for the Rho GTPase, so that loss of HUM-7 enhances Rho-dependent epidermal cell behaviors. We identify SAX-3/ROBO as an upstream signal that contributes to attenuated Rho activation through its regulation of HUM-7/Myo9. These studies identify a new role for Rho during epidermal cell migrations, and suggest that Rho activity is regulated by SAX-3/ROBO acting on the RhoGAP HUM-7.

Download Full-text

RhoGAP RGA-8 supports morphogenesis in C. elegans by polarizing epithelia through CDC-42

10.1101/2019.12.15.877332 ◽

2019 ◽

Author(s):

Hamidah Raduwan ◽

Shashikala Sasidharan ◽

Luigy Cordova Burgos ◽

Andre G. Wallace ◽

Martha C. Soto

Keyword(s):

Cell Shape ◽

Control Cell ◽

Molecular Data ◽

Regulatory Motifs ◽

C Elegans ◽

Cell Embryo ◽

Embryonic Morphogenesis ◽

The One ◽

Muscle Myosin ◽

Shape Changes

AbstractCDC-42 regulation of non-muscle myosin/NMY-2 is required for polarity maintenance in the one-cell embryo of C. elegans. CDC-42 and NMY-2 regulate polarity throughout embryogenesis, but their contribution to later events of morphogenesis are less understood. We have shown that epidermal enclosure requires the GTPase CED-10/Rac1 and WAVE/Scar complex, its effector, to promote protrusions that drive enclosure through the branch actin regulator Arp2/3. Our analysis here of RGA-8, a homolog of SH3BP1/Rich1/ARHGAP17/Nadrin, with BAR and RhoGAP motifs, suggests it regulates CDC-42, so that NMY-2 promotes two events of epidermal morphogenesis: ventral enclosure and elongation. Genetic and molecular data suggest RGA-8 regulates CDC-42, and the CDC-42 effectors WSP-1 and MRCK-1, in parallel to F-BAR proteins TOCA-1 and TOCA-2. The RGA-8-CDC-42-WSP-1 pathway enriches myosin in migrating epidermal cells during ventral enclosure. We propose TOCA proteins and RGA-8 use BAR domains to localize and regenerate CDC-42 activity, thus regulating F-actin levels, through the branched actin regulator WSP-1, and myosin polarity through the myosin kinase MRCK-1. Regulated CDC-42 thus polarizes epithelia, to control cell migrations and cell shape changes of embryonic morphogenesis.SummaryRGA-8, a protein with membrane binding and actin regulatory motifs, promotes embryonic morphogenesis by localizing active CDC-42 in developing epithelia, thus controlling actin and actin motors during cell movements.

Download Full-text