Pei-Lung Chen et al. (2004) East Coast Worm Meeting "Translational control in the germ plasm: nos-2 RNA regulation."

Pei-Lung Chen, Ingrid D'Agostino, Geraldine Seydoux

[East Coast Worm Meeting, 2004]

Nanos is a conserved regulator of germ cell differentiation. In many organisms, nanos RNA is maternally inherited and is translated only in the germ plasm, a specialized cytoplasm that segregates with the germline during early embryogenesis. How nanos translation is activated specifically in the germ plasm is poorly understood. We are investigating this question using the C. elegans nanos homolog nos-2 . nos-2 encodes a maternal RNA that is enriched on P granules (germ plasm organelles) and is translated specifically in the germline founder cell, P 4 , and its daughters the primordial germ cells Z2 and Z3. This expression depends on the nos-2 3'UTR. A GFP:Histone H2B: nos-2 3'UTR transgene (driven by the pie-1 promoter) is expressed only in P 4 and Z2 and Z3. To begin to identify the transacting factors that act on the nos-2 3'UTR, we have examined the expression of the GFP: H2B: nos-2 3'UTR transgene in 2 classes of mutants: mutants in P granule components and mutants in the RNAi pathway. Our initial results indicate that certain P granules components are needed to repress ectopic nos-2 translation, whereas others are needed to activate nos-2 translation in P 4 .

Pei-Lung Chen et al. (2004) East Coast Worm Meeting "Translational control in the germ plasm: nos-2 RNA regulation."

Geraldine Seydoux, Ingrid D'Agostino, Pei-Lung Chen

[East Coast Worm Meeting, 2004]

Nanos is a conserved regulator of germ cell differentiation. In many organisms, nanos RNA is maternally inherited and is translated only in the germ plasm, a specialized cytoplasm that segregates with the germline during early embryogenesis. How nanos translation is activated specifically in the germ plasm is poorly understood. We are investigating this question using the C. elegans nanos homolog nos-2 . nos-2 encodes a maternal RNA that is enriched on P granules (germ plasm organelles) and is translated specifically in the germline founder cell, P 4 , and its daughters the primordial germ cells Z2 and Z3. This expression depends on the nos-2 3'UTR. A GFP:Histone H2B: nos-2 3'UTR transgene (driven by the pie-1 promoter) is expressed only in P 4 and Z2 and Z3. To begin to identify the transacting factors that act on the nos-2 3'UTR, we have examined the expression of the GFP: H2B: nos-2 3'UTR transgene in 2 classes of mutants: mutants in P granule components and mutants in the RNAi pathway. Our initial results indicate that certain P granules components are needed to repress ectopic nos-2 translation, whereas others are needed to activate nos-2 translation in P 4 .

Schreier J et al. (2022) Nat Cell Biol "Membrane-associated cytoplasmic granules carrying the Argonaute protein WAGO-3 enable paternal epigenetic inheritance in Caenorhabditis elegans."

Gleason EJ, Oorschot V, Seistrup AS, Butter F, Schreier J, de Jesus Domingues AM, Phillis S, Dietz S, Bronkhorst AW, Phillips CM, Nguyen DAH, Boermel M, Ketting RF, L'Hernault SW

[Nat Cell Biol, 2022]

Epigenetic inheritance describes the transmission of gene regulatory information across generations without altering DNA sequences, enabling offspring to adapt to environmental conditions. Small RNAs have been implicated in this, through both the oocyte and the sperm. However, as much of the cellular content is extruded during spermatogenesis, it is unclear whether cytoplasmic small RNAs can contribute to epigenetic inheritance through sperm. Here we identify a sperm-specific germ granule, termed the paternal epigenetic inheritance (PEI) granule, that mediates paternal epigenetic inheritance by retaining the cytoplasmic Argonaute protein WAGO-3 during spermatogenesis in Caenorhabditis elegans. We identify the PEI granule proteins PEI-1 and PEI-2, which have distinct functions in this process: granule formation, Argonaute selectivity and subcellular localization. We show that PEI granule segregation is coupled to the transport of sperm-specific secretory vesicles through PEI-2 in an S-palmitoylation-dependent manner. PEI-like proteins are found in humans, suggesting that the identified mechanism may be conserved.

Schreier, Jan et al. (2021) International Worm Meeting "A novel sperm-specific compartment secures a cytoplasmic Argonaute protein for paternal epigenetic inheritance of small RNA-mediated gene silencing"

Boermel, Mandy, Butter, Falk, Dietz, Sabrina, Schreier, Jan, Ketting, Rene, Seistrup, Ann-Sophie, Domingues, Antonio, Bronkhorst, Alfred, Oorschot, Viola, L'Hernault, Steven, Phillips, Carolyn, Nguyen, Dieu

[International Worm Meeting, 2021]

Germ cells possess specialized perinuclear, phase-separated compartments, also named condensates. Amongst others, they contain the mRNA surveillance machinery responsible for transposon silencing and fertility. In the nematode Caenorhabditis elegans, three condensates, P granules, Z granules and Mutator foci, are home to RNA interference-related pathways, driven by a highly diversified Argonaute sub-clade (WAGO) that mediates gene silencing. Intriguingly, it has been shown that WAGO-mediated gene silencing can be inherited via both oocyte and sperm. Especially the inheritance via sperm is remarkable, since significant amounts of cellular material, including Argonaute proteins, are expelled from maturing spermatids into so-called residual bodies. How then does sperm-mediated inheritance of cytoplasmic RNAi work? We genetically identify WAGO-3 as a major Argonaute protein required for the paternal inheritance of endogenous small RNAs. Just like other Argonaute proteins, like WAGO-1 and ALG-3, WAGO-3 localizes to P granules in naive germ cells. During spermatogenesis, however, P granules disappear and WAGO-3, but not WAGO-1 and ALG-3, accumulates in a newly identified condensate, the PEI granule. In contrast to P granules, PEI granules remain stable during later stages of spermatogenesis. They are retained within maturing spermatids and selectively keep WAGO-3 from accumulating in the residual body. Using immunoprecipitation experiments followed by label-free quantitative mass spectrometry, we identified two uncharacterized proteins: PEI-1 and PEI-2. Both proteins are specifically expressed during spermatogenesis and we dissect their roles in PEI granule transport and function. Based on correlative light and electron microscopy (CLEM) and genetic studies, proper segregation of PEI granules in mature sperm is coupled, likely via S-palmitoylation, to the myosin-driven transport of membranous organelles. Our results identify a new sperm-specific condensate, which we call PEI granules. While not essential for spermatogenesis, PEI granules are required for paternal inheritance of small RNAs and we reveal a novel mechanism for the subcellular sorting of condensates through coupling to transport of membranous structures. pei-like genes are also found in human and often expressed in testis, suggesting that the here identified mechanism of subcellular transport of membraneless organelles may be more broadly conserved.

Maine EM et al. (1994) Worm Breeder's Gazette "Mutations That Enhance glp-1 Identify Genes Required For Various Aspects of Germline Development."

Gelber MB, Smardon AM, Shu P, Qiao L, Maine EM, Lissemore JL

[Worm Breeder's Gazette, 1994]

Mutations that enhance glp-1 identify genes required for various aspects of germline development. Eleanor Maine, Li Qiao, Jim Lissemore-, Pei Shu, Anne Smardon, and Melanie Gelber. Biology Dept., Syracuse University, Syracuse, NY 13244 and Biology Dept., John Carroll University, Cleveland, OH 44118.

Chris Merritt et al. (2005) International Worm Meeting "A stem-loop in the 3UTR of nos-2 is required for translational repression in oocytes."

Pei-Lung Chen, Kuppuswamy Subramaniam, Chris Merritt, Ingrid D'Agostino, Geraldine Seydoux

[International Worm Meeting, 2005]

Nanos is a conserved regulator of germ cell differentiation. In many organisms, nanos RNA is maternally inherited and is translated only in the germ plasm, a specialized cytoplasm that segregates with the germline during early embryogenesis. How nanos translation is activated specifically in the germ plasm is poorly understood. We are investigating this question using the C. elegans nanos homolog nos-2. nos-2 encodes a maternal RNA that is enriched on P granules (germ plasm organelles) and is translated specifically in the germline founder cell, P4 , and its daughters the primordial germ cells Z2 and Z3. This expression depends on the nos-2 3'UTR. A GFP:Histone H2B:nos-2 3'UTR transgene (driven by the pie-1 promoter) is expressed only in P4 and Z2 and Z3. To begin to identify the transacting factors that act on the nos-2 3'UTR, we compared nos-2 3UTR sequences from C. elegans, C. briggsae and C. remanei. We noticed several conserved blocks including a conserved inverted repeat with the potential to form a stem loop. To test the significance of this structure, we created two mutations in the GFP:Histone H2B:nos-2 3'UTR transgene predicted to disrupt pairing in the stem (M1 and M2), and a double mutant (M1M2) predicted to restore pairing. We found that the M1 and M2 mutations lead to ectopic expression of the GFP:H2B reporter in oocytes. In contrast, the M1M2 double mutant was expressed in a pattern indistinguishable from wild-type (OFF in oocytes, ON in P4 and Z2 and Z3), consistent with restoration of the stem loop. We conclude that inhibition of nos-2 translation in oocytes depends on the formation of a stem-loop in the nos-2 3UTR. Interestingly translational inhibition of Nanos in Drosophila oocytes also depends on a stem loop (Forrest, K.M. et al. (2004). Development 131: 5849-5857).

Po MD et al. (2012) Neuron "Releasing the inner inhibition for axon regeneration."

Po MD, Calarco JA, Zhen M

[Neuron, 2012]

The adult mammalian central nervous system exhibits restricted regenerative potential. Chen etal. (2011) and El Bejjani and Hammarlund (2012) used Caenorhabditis elegans to uncover intrinsic factors that inhibit regeneration of axotomized mature neurons, opening avenues for potential therapeutics.

Johnson CD et al. (2007) Cancer Res "The let-7 microRNA represses cell proliferation pathways in human cells."

Johnson CD, Wilson M, Brown D, Ovcharenko D, Kelnar K, Slack FJ, Byrom M, Esquela-Kerscher A, Shelton J, Chin L, Stefani G, Shingara J, Wang X

[Cancer Res, 2007]

MicroRNAs play important roles in animal development, cell differentiation, and metabolism and have been implicated in human cancer. The let-7 microRNA controls the timing of cell cycle exit and terminal differentiation in Caenorhabditis elegans and is poorly expressed or deleted in human lung tumors. Here, we show that let-7 is highly expressed in normal lung tissue, and that inhibiting let-7 function leads to increased cell division in A549 lung cancer cells. Overexpression of let-7 in cancer cell lines alters cell cycle progression and reduces cell division, providing evidence that let-7 functions as a tumor suppressor in lung cells. let-7 was previously shown to regulate the expression of the RAS lung cancer oncogenes, and our work now shows that multiple genes involved in cell cycle and cell division functions are also directly or indirectly repressed by let-7. This work reveals the let-7 microRNA to be a master regulator of cell proliferation pathways. [Cancer Res 2007;67(16):7713-22].

Silverstein NJ et al. (2017) Immunity "Interleukin-17: Why the Worms Squirm."

Huh JR, Silverstein NJ

[Immunity, 2017]

IL-17 is a cytokine known primarily for its role in inflammation. In a recent issue of Nature, Chen etal. (2017) demonstrate that IL-17 plays a neuromodulatory role in Caenorhabditis elegans by acting directly on neurons to amplify neuronal responses to stimuli and produce changes in animal behavior.

Artan M et al. (2016) Dev Cell "Heat FLiPs a Hormonal Switch for Longevity."

Lee SV, An SW, Artan M

[Dev Cell, 2016]

Temperature-sensing neurons in C.elegans reduce the life-shortening effects of high temperatures via steroid signaling. In this issue of Developmental Cell, Chen etal. (2016) elucidate the underlying mechanisms by which the transcription factor CREB induces the neuropeptide FLP-6 in the temperature-sensing neurons to counteract the life-shortening effects of high temperature.