Shi, Cheng et al. (2013) International Worm Meeting "Mating-induced somatic collapse reveals a novel soma-germline interaction."

Murphy, Coleen, Shi, Cheng

[International Worm Meeting, 2013]

Interactions between the germline and the soma are important to optimize reproduction and to influence somatic aging. The prevailing germline-soma model suggests that the lifespan shortening signal from the germline antagonizes the lifespan lengthening signal in the somatic gonad in C. elegans. Previous studies focused on removal of germline cells and its longevity-repressing activity to reveal the somatic gonad lifespan-extending signal. We have identified a new phenomenon linking reproductive status to longevity and have illustrated the elusive lifespan-shortening signal for the first time: in C. elegans, mating leads to "post-mating somatic collapse" (PMSC), a state in which mated worms shrink pronouncedly and die early, compressing the post-reproductive life span. The post-mating shrinking and lifespan phenomena are genetically separable, and the DAF-12 steroid receptor and DAF-16/FOXO transcription factor are involved in regulating different aspects of PMSC. Components from males contribute differently to PMSC. Likewise, hermaphrodites have germline-dependent and germline-independent responses that process the corresponding male-initiated signals. Post-mating somatic collapse may be an extreme version of the influence that males in many species exert on female behavior to maximize their own reproductive success. Our study provides new insight into the communication between males and the female germline and soma to regulate reproduction and longevity.

Shi, Cheng et al. (2021) International Worm Meeting "piRNA pathway-mediated Hedgehog signaling encodes a germline-to-soma pro-aging signal"

Murphy, Coleen, Shi, Cheng

[International Worm Meeting, 2021]

The reproductive system regulates the aging of the soma. Removal of the germline extends somatic lifespan through conserved pathways including Insulin, mTOR, and steroid signaling, while germline hyperactivity cuts lifespan short through mechanisms that are still elusive. Here, we show that mating-induced germline hyperactivity leads to the downregulation of piRNAs, which in turn release silencing on their targets, two Hedgehog-like ligand encoding genes. Germline-originating Hedgehog signaling is perceived by the Patched-related family receptors in the soma, ultimately causing somatic collapse and early death. Our results reveal an unconventional role of the piRNA pathway and Hedgehog signaling in longevity regulation, and suggest that Hedgehog signaling controlled by the tunable piRNA pathway encodes the previous unknown germline-to-soma pro-aging signal.

Shi, Cheng et al. (2019) International Worm Meeting "Insulin-like peptides and the mTOR-TFEB pathway protect C. elegans hermaphrodites from Mating-induced Death."

Shi, Cheng, Murphy, Coleen

[International Worm Meeting, 2019]

C. elegans lifespan is shortened by mating, but must be delayed long enough for successful reproduction. Susceptibility to brief mating-induced death increases with age; surprisingly, this is not due to declining health, but to loss of protection upon self-sperm depletion. Self-sperm maintains expression of a DAF-2 insulin-like antagonist, INS-37, which promotes the nuclear localization of HLH-30/TFEB, a pro-longevity regulator. Mating induces the agonist INS-8, promoting HLH-30 nuclear exit and subsequent death. In opposition to the protective role of HLH-30 and DAF-16/FOXO, TOR/LET-363 and the IIS-regulated Zn-finger transcription factor PQM-1 promote seminal-fluid-induced killing. Self-sperm maintenance of nuclear HLH-30/TFEB allows hermaphrodites to resist mating-induced death, increasing the chances that mothers will survive through reproduction. The hijacking of the IIS pathway by males is combated by the mother's expression of an insulin antagonist that keeps her healthy through the activity of pro-longevity factors, as long as she has her own sperm to utilize. ** If possible, I would prefer that this abstract please be considered with the abstract submitted by Lauren N. Booth, Travis J. Maures, Robin W. Yeo, and Anne Brunet ("Self-sperm induce resistance to the detrimental effects of sexual encounters with males in hermaphroditic nematodes").

Moore, Rebecca et al. (2017) International Worm Meeting "A screen for reproductive span extension genes identifies repx-1, a novel regulator of reproductive span."

Moore, Rebecca, Lou, Shijing, Zhuang, Eileen, Murphy, Coleen, Shi, Cheng

[International Worm Meeting, 2017]

Female age-related reproductive cessation, which is generally caused by decreasing oocyte quality, is one of the earliest age-related declines observed in humans, but little is known about its genetic regulation. C. elegans experiences a similar decline of oocyte quality with age, but can be maintained through the manipulation of endocrine signaling. In order to better understand the biology of reproductive aging, we performed a small Mos1-mediated insertional mutagenesis screen to identify mutants with extended reproduction span. Five genes were identified, including repx-1 (reproductive span extension-1), a putative tyrosine kinase with homology to FGFR. repx-1 mutants extend reproductive span and slow age-related declines in oocyte and germline morphology, but are not long-lived, uncoupling these aging phenotypes. repx-1 does not act through known reproductive span regulators (i.e. TGF-b and Insulin signaling pathways), but shares downstream biomarkers of oocyte quality. repx-1 acts non-autonomously in the intestine to regulate germline quality. To identify potential interacting partners, we performed a yeast 2-hybrid screen, and found that FAR-2, predicted to be involved in fatty acid and retinoid scavenging, bound to REPX-1. Like repx-1, far-2 mutants also extend reproductive span, and far-2 functions upstream of repx-1 in the body wall muscle and vulval cells of adult hermaphrodites. These results suggest that additional pathways that may modulate late-life reproduction, independent of lifespan regulation, await discovery.

Martin Victor et al. (2001) International C. elegans Meeting "The HAT activity of CBP-1 is indispensable for its biological function during C. elegans embryogenesis"

Craig C Mello, Martin Victor, Yang Shi

[International C. elegans Meeting, 2001]

CBP/p300 represent a conserved family of transcriptional cofactors possessing histone acetyltransferase (HAT) activity. This group of proteins has been shown to play critical roles in differentiation and cell proliferation in C. elegans , Drosophila , mouse and human. Despite their importance, the mechanisms by which they regulate transcription and thus exert their biological functions are poorly understood. A central question is whether the HAT activity is essential for the biological functions of these proteins. In this study, we investigated the importance of the HAT activity for CBP-1 in C. elegans . We show that a truncated CBP-1 protein lacking the HAT domain fails to promote differentiation, consistent with the notion that the HAT activity of CBP-1 is essential for its biological functions. To further address this question, we used a chemical that has been shown to be a specific inhibitor of the enzymatic activity of CBP/p300 HAT. Injection of this chemical into the gonads of the hermaphrodite mothers resulted in dead embryos arrested at different stages of development. Significantly, some of these embryos appear identical to cbp-1(RNAi) embryos in every aspect, as judged by the excess cell number, lack of endoderm and mesoderm tissues but excess neuronal differentiation (Shi and Mello, 1998). Taken together, our findings provide in vivo evidence that the HAT activity is not only critical, but also may be the only biochemical activity that is necessary for the biological functions of CBP-1. Shi, Y. and Mello,C. (1998), 'A CBP/p300 homolog specifies multiple differentiation pathways in Caenorhabditis elegans .' Genes Dev. 12(7), 943-55.

Howard Chang et al. (2003) International Worm Meeting "Functional analysis of AMPA-type glutamate receptor sequences and their contribution to receptor localization at synapses"

Christopher Rongo, Howard Chang

[International Worm Meeting, 2003]

The modulation of AMPA-type glutamate receptor localization to central nervous system synapses is an important component of synaptic plasticity, and can be triggered by LTP (Long Term Potentiation) and CaMKII (Type II calcium-calmodulin-dependent protein kinase) activity. (1, 2). In mammalian hippocampal neurons, the different AMPA receptor subunits GluR1, GluR2, GluR3, and GluR4 are proposed to form heteromultimers, and individual subunits can confer localization specificity to the multimeric channels that they comprise (2,3). One likely explanation for such subunit specificity is that the targeting of AMPA receptors to the synapses is probably due to the interaction of PDZ domain-containing proteins and the receptor subunit cytosolic tail sequences (4). In C. elegans, there are four AMPA receptor subunits that are expressed in the command interneurons, including, GLR-1, GLR-2, GLR-4 and GLR-5 (5,6). GLR-1 has C-terminal sequence that contributes to channel turnover (7). We have identified a glutamate receptor subunit domain that appears to be instructive for channel localization. This new finding may shed a new light on the localization and regulation of AMPA-type glutamate receptors in response to plasticity at synapses. (1) Rongo et al. Nature (1999), vol. 402, p. 195 (2) Shi et al. Science (1999), vol. 284, p.1811 (3) Shi et al. Cell (2001), vol. 105, p. 331 (4) Rongo et al. Cell (1998), vol. 94, p. 751 (5) Brockie et al. J. Neuroscience (2001), vol. 21(5), p. 1510 (6) Mellem et al. Neuron 2002 Dec 5; 36:933-944 (7) Burbea M et al. Neuron 2002 Jul 3;35(1):107-20

Booth, L. et al. (2019) International Worm Meeting "Self-sperm induce resistance to the detrimental effects of sexual encounters with males in hermaphroditic nematodes."

Maures, T., Brunet, A., Booth, L., Yeo, R.

[International Worm Meeting, 2019]

Sexual interactions have a potent influence on health in several species, including mammals. C. elegans is well suited to study the impact of sexual interactions on lifespan, as males trigger the premature death of the opposite sex (hermaphrodites). Previous work has identified strategies used by males to accelerate the demise of the opposite sex. But whether counter-strategies evolved to protect hermaphrodites against males remains mysterious. Here, by shortening the time of sexual interactions, we discover that young C. elegans hermaphrodites are remarkably resistant to brief sexual encounters with males. Young hermaphrodites live a normal lifespan even after successfully mating with males, whereas older hermaphrodites succumb prematurely. Surprisingly, it is not their youthfulness that protects young hermaphrodites from males, but the fact that they have self-sperm. Feminized individuals that lack self-sperm succumb even at a young age after mating with males. Conversely, masculinized individuals that only have self-sperm live a normal lifespan even after mating with males at an older age. The beneficial effect of self-sperm is not due to fertilization. Instead, self-sperm protect the hermaphrodite soma via a sperm-sensing pathway that was previously known to act in the germline. This sperm-sensing pathway is also present in females, and activation of this pathway triggers somatic protection from the negative impact of males on feminized individuals. Interestingly, the role of self-sperm in protecting against the detrimental effects of males evolved independently twice in hermaphroditic nematodes. Thus, endogenous strategies to delay the negative effect of sexual interactions may represent a key evolutionary innovation to maximize reproductive success. While self-sperm are specific to hermaphrodites, they trigger pathways that are conserved in all species, and this could give new insights into the role of gametes in 'resetting' the aging clock. ** If possible, I would prefer that this abstract please be considered with the abstract submitted by Cheng Shi and Coleen Murphy ("Insulin-like peptides and the mTOR-TFEB pathway protect C. elegans hermaphrodites from Mating-induced Death")

David Katz et al. (2006) Development & Evolution Meeting "Histone H3 Lysine 4 Guards The Immortality Of The Germline"

William Kelly, David Katz, Thomas Edwards

[Development & Evolution Meeting, 2006]

In the C. elegans early embryo, the chromatin in all blastomeres initially contain the euchromatic mark, di-methylation of histone H3 on lysine 4 (H3K4me2). However, upon their birth, the primordial germ cells Z2 and Z3 uniquely lose this mark. This appears to be a conserved characteristic of primordial germ cells as Drosophila pole cells also initially lack this modification. The loss of H3K4me2 has been proposed to be necessary for protecting the totipotency of the germline through chromatin-based transcriptional repression, but the mechanism of its removal is not understood. Recently, Shi et al. demonstrated that the mammalian amine oxidase LSD1 can specifically demethylate H3K4me2 (Shi et al. 2004). C. elegans has three lsd1 homologs : spr-5, amx-1 and T08D10.2. In order to ask if these genes play a role in the chromatin remodeling of Z2 and Z3, we inactivated them individually and in combination. RNAi or genetic mutation of any of these genes individually has no affect on H3K4me2 levels in Z2 and Z3. To test for redundant roles in the chromatin remodeling of Z2 and Z3, we generated a spr-5;amx-1 double mutant from two existing putative null mutations. Although the double mutants display multiple pleiotropic phenotypes, we observed no immediate effects on H3meK4 levels in Z2 and Z3. However, after multiple generations the double mutant exhibits a germline mortality phenotype, in which an increasing fraction of progeny in the population grow up sterile(black sterile phenotype). Strikingly, in these later generations, the double mutants exhibit retention of H3K4me2 in Z2 and Z3, further correlating repressive chromatin with maintenance of the germ cell lineage. In addition, the multiple generations that are required for this phenotype suggest that there can be stable inheritance of epigenetic defects through the germline and that the H3K4 demethylases may play a role in resetting H3K4 methylation at each generation.

Wang, Lin et al. (2017) International Worm Meeting "Dissecting the roles of the ADAM10 metalloprotease SUP-17 in the BMP signaling pathway in Caenorhabditis elegans."

Liu, Jun, Liu, Zhiyu, Shi, Herong, Wang, Lin

[International Worm Meeting, 2017]

BMPs (Bone Morphogenetic Proteins) belong to the TGFbeta superfamily of ligands, and mediate a highly conserved signal transduction cascade. Upon ligand binding, type II receptors phosphorylate type I receptors, which in turns phosphorylate R-Smads (receptor regulated Smads). Phosphorylated R-Smads then complex with co-Smad (common mediator smad) and enter the nucleus to regulate gene transcription with different co-factors. BMPs play important roles in developmental and physiological processes. Malfunction of the pathway in humans can cause various disorders, such as skeleton diseases, heart diseases and cancers. So it is critical to strictly regulate the level of BMP signaling spatiotemporally. Using a highly specific genetic screen, we have identified several modulators of the BMP pathway in C. elegans. These include the Neogenin homolog UNC-40 [1], two paralogous tetraspanin proteins, TSP-12 and TSP-14, and an ADAM10 metalloproteinase (A Disintegrin and Metalloproteinase 10) SUP-17 [2]. We use the CRISPR/Cas9 system and tagged the endogenous TSP-12, SUP-17 and UNC-40 proteins with different fluorescence tags. We found that TSP-12 is localized to the cell surface and intracellular vesicles, and that TSP-12 can bind to SUP-17 and promote its cell surface localization. We have genetic evidence and preliminary biochemical evidence showing that UNC-40 is one, but not the only, substrate of SUP-17 in BMP signaling. We are currently identifying additional substrate(s) of SUP-17 in BMP signaling. Our work highlights the importance of intracellular signaling and protease processing in the regulation of BMP signaling. [1] Tian C, Shi H, Xiong S, Hu F, Xiong WC, Liu J. The neogenin/DCC homolog UNC-40 promotes BMP signaling via the RGM protein DRAG-1 in C. elegans. Development. 2013;140(19):4070-80. doi: 10.1242/dev.099838. PubMed PMID: 24004951; PubMed Central PMCID: PMCPMC3775419. [2] Wang L, Liu Z, Shi H, Liu J. Two Paralogous Tetraspanins TSP-12 and TSP-14 Function with the ADAM10 Metalloprotease SUP-17 to Promote BMP Signaling in Caenorhabditis elegans. PLoS Genet. 2017;13(1):e1006568. doi: 10.1371/journal.pgen.1006568. PubMed PMID: 28068334; PubMed Central PMCID: PMCPMC5261805.

G Kao et al. (1999) International C. elegans Meeting "Characterization of Laminin beta and gamma Genes."

G Kao, C Huang, WG Wadsworth

[International C. elegans Meeting, 1999]

We have characterized laminin b (lam-1) and laminin g (lam-2) genes. The sequencing project has uncovered genes for one isoform each of the two subunits and two isoforms of laminin a , epi-1 and lam-3. (See abstract by Cheng et al.). This indicates that two types of trimers likely are form in basement membranes : a A bg and a B bg . A hypomorphic mutation (rh219) exists in lam-1, whose phenotypes we have described in previous meetings (IWM 1997). Both lam-1(RNAi) and lam-2(RNAi) animals arrest development during morphogenesis. Significantly, this phenotype is identical to the arrest seen in double knockout of epi-1 and lam-3, and is more severe than either knockout alone. We examined the expression patterns of lam-1 and lam-2 using promoter:GFP fusions. Both genes are expressed in body wall muscles, pharynx, vulval muscles, the rectal muscle group and the distal tip cells. The expression patterns of b and g subunit genes overlap with and are more widespread than either epi-1 or lam-3 alone. Taken together these results suggest that lam-1 and lam-2 are found in all basement membranes and indicate that trimers a A bg and a B bg are formed.