Liao Y et al. (1999) J Biol Chem "RA-GEF, a novel Rap1A guanine nucleotide exchange factor containing a Ras/Rap1A-associating domain, is conserved between nematode and humans."

Liao Y, Goshima M, Kariya K-i, Hu CD, Kataoka T, Jin TG, Watari Y, Yamawaki-Kataoka Y, Okada T, Gao X, Shibatohge M

[J Biol Chem, 1999]

A yeast two-hybrid screening for Ras-binding proteins in nematode Caenorhabditis elegans has identified a guanine nucleotide exchange factor (GEF) containing a Ras/Rap1A-associating (RA) domain, termed Ce-RA-GEF. Both Ce-RA-GEF and its human counterpart Hs-RA-GEF possessed a PSD-95/DlgA/ZO-1 (PDZ) domain and a Ras exchanger motif (REM) domain in addition to the RA and GEF domains. They also contained a region homologous to a cyclic nucleotide monophosphate-binding domain, which turned out to be incapable of binding cAMP or cGMP. Although the REM and GEF domains are conserved with other GEFs acting on Ras family small GTP-binding proteins, the RA and PDZ domains are unseen in any of them. Hs-RA-GEF exhibited not only a GTP-dependent binding activity to Rap1A at its RA domain but also an activity to stimulate GDP/GTP exchange of Rap1A both in vitro and in vivo at the segment containing its REM and GEF domains. However, it did not exhibit any binding or GEF activity toward Ras. On the other hand, Ce-RA-GEF associated with and stimulated GDP/GTP exchange of both Ras and Rap1A. These results indicate that Ce-RA-GEF and Hs-RA-GEF define a novel class of Rap1A GEF molecules, which are conserved through evolution.

Lin C et al. (2019) Biofactors "Rosmarinic acid improved antioxidant properties and healthspan via the IIS and MAPK pathways in Caenorhabditis elegans."

Xi Y, Lin C, Zhong Q, Zhang X, Zheng H, Xiao J, Cao Y, Chen Y

[Biofactors, 2019]

Rosmarinic acid (RA) has a wide range of biological effects, including the antioxidation and antiaging. However, the detailed mechanisms remain unclear but highly attractive. Herein, RA promoted lifespan and motoricity in a dose-dependent manner, and reduced fat store without threatening fertility in Caenorhabditis elegans. In term of antioxidant efficacy, catalase activity, glutathione peroxidas activity, reduced glutathione content, and reduced glutathione/oxidized glutathione ratio were enhanced. And malondialdehyde content was diminished significantly. Moreover, RA increased survival under acute oxidative and thermal stress, and suppressed intestinal lipofuscin accumulation. So the improvement of lifespan mediated by RA could be related with its strong antioxidant properties. Furthermore, RA was absorbed by worms. Further research in pursuit of the mechanism showed that longevity induced by RA was involved with the genes sod-3, sod-5, ctl-1, daf-16, ins-18, skn-1, and sek-1, but was independent of subcellular localization of DAF-16. These findings indicated that RA had a potential for promoting healthy lifespan.

Chen Y et al. (2024) Mol Neurobiol "Rosmarinic acid ameliorated oxidative stress, neuronal injuries, and mitochondrial dysfunctions mediated by polyglutamine and ɑ-synuclein in Caenorhabditis elegans models."

Zeng Y, Liu Y, Liu Q, Cao Y, Xu R, Chen W, Liu G, Chen Y

[Mol Neurobiol, 2024]

Numerous natural antioxidants have been developed into agents for neurodegenerative diseases (NDs) treatment. Rosmarinic acid (RA), an excellent antioxidant, exhibits neuroprotective activity, but its anti-NDs efficacy remains puzzling. Here, Caenorhabditis elegans models were employed to systematically reveal RA-mediated mechanisms in delaying NDs from diverse facets, including oxidative stress, the homeostasis of neural and protein, and mitochondrial disorders. Firstly, RA significantly inhibited reactive oxygen species accumulation, reduced peroxide malonaldehyde production, and strengthened the antioxidant defense system via increasing superoxide dismutase activity. Besides, RA reduced neuronal loss and ameliorated polyglutamine and ɑ-synuclein-mediated dyskinesia in NDs models. Further, in combination with the data and molecular docking results, RA may bind specifically to Huntington protein and ɑ-synuclein to prevent toxic protein aggregation and thus enhance proteostasis. Finally, RA ameliorated mitochondrial dysfunction including increasing adenosine triphosphate and mitochondrial membrane potential levels and rescuing mitochondrial membrane proteins' expressions and mitochondrial structural abnormalities via regulating mitochondrial dynamics genes and improving the mitochondrial kinetic homeostasis. Thus, this study systematically revealed the RA-mediated neuroprotective mechanism and promoted RA as a promising nutritional intervention strategy to prevent NDs.

Wong, Wan-Rong et al. (2021) MicroPubl Biol

Oh, Jun Young, Wong, Wan-Rong, Maher, Shayda, Sternberg, Paul W, Gharib, Shahla, Brugman, Katherine I

[MicroPubl Biol, 2021]

Retinoic acid (RA), the active metabolite of vitamin A, broadly regulates gene expression. The RA signaling pathway plays an essential role in embryonic development, including the development of the body axis, eye, brain, and heart (Ghyselinck & Duester, 2019). One of the key enzymes in the biosynthesis of RA is aldehyde dehydrogenase 1 family member A3 (ALDH1A3). ALDH1A3 converts retinaldehyde to retinoic acid and it is expressed early in forebrain development (McCaffery & Drager, 1994). Several mutations in ALDH1A3 have been implicated in patients with autosomal recessive microphthalmia and other neurological disorders (Fares-Taie et al., 2013; Roos et al., 2014). However, current animal models of ALDH1A3 have large truncations of the protein. Direct evidence of the effects of missense variants on ALDH1A3 protein activity has not yet been obtained.

Vader G et al. (2014) Dev Cell "HORMA domains at the heart of meiotic chromosome dynamics."

Musacchio A, Vader G

[Dev Cell, 2014]

HORMA domain proteins are required for the careful orchestration of chromosomal organization during meiosis. Kim et al. (2014) and Silva et al. (2014) now provide structural and functional insights into the roles of C. elegans HORMA proteins, revealing parallels to the function of the HORMA protein MAD2 in mitotic checkpoint signaling.

Samuel ADT et al. (2003) J Neurosci "Synaptic activity of the AFD neuron in Caenorhabditis elegans correlates with thermotactic memory."

Murthy VN, Samuel ADT, Silva RA

[J Neurosci, 2003]

Thermotactic behavior in Caenorhabditis elegans is sensitive to both a worm's ambient temperature (T-amb) and its memory of the temperature of its cultivation (T-cult). The AFD neuron is part of a neural circuit that underlies thermotactic behavior. By monitoring the fluorescence of pH-sensitive green fluorescent protein localized to synaptic vesicles, we measured the rate of the synaptic release of AFD in worms cultivated at temperatures between 15 and 25degreesC, and subjected to fixed, ambient temperatures in the same range. We found that the rate of AFD synaptic release is high if either T-amb > T-cult or T-amb > T-cult, but AFD synaptic release is low if T-amb congruent to T-cult. This suggests that AFD encodes a direct comparison between T-amb and T-cult.

Liu G et al. (2000) Int J Cancer "Down-regulation of the Diphthamide biosynthesis protein 2-like gene during retinoid-induced differentiation and apoptosis: implications against its tumor-suppressor activity."

Levi G, Wu M, Ferrari N, Liu G

[Int J Cancer, 2000]

Retinoids, synthetic and natural analogs of retinoic acid (RA) have profound effects on the proliferation and differentiation of many cell types; this accounts for their beneficial effects in the treatment of certain neoplasias. We have employed mRNA differential display to characterize genes associated with differentiation and apoptosis induced by all-trans RA in human lung cancer cells. We have identified a cDNA corresponding to the sequence of the known gene diphthamide biosynthesis protein 2-like (DPH2L). Although the function of this gene remains unknown, as it was first isolated from the critical region of deletion on chromosome 17p13.3 in human ovarian carcinoma, it has been regarded as a candidate tumor-suppressor gene. In this report, we provide evidence that DPH2L is down-regulated during differentiation or apoptosis in several cancer cell lines after treatment with all-trans RA or N-(4-hydroxyphenyl)retinamide and during cell-cycle arrest. Moreover, stable expression of DPH2L-specific anti-sense construct leads to inhibition of cell proliferation. Our results suggest that DPH2L in not a conventional tumor-suppressor gene. Instead, it may be a growth regulator and its down-regulation might be permissive for the transition from cell growth to differentiation or apoptosis. DPH2L might be a useful tool in the prognosis of neoplastic diseases.

Jurgen A Riedl et al. (2002) European Worm Meeting "Identification of novel downstream effectors of Rap1 and Rap2."

Wendy van Berkel, Jurgen A Riedl, Johannes L Bos, Fried J T Zwartkruis

[European Worm Meeting, 2002]

Rap1 and Rap2 belong to the Ras superfamily of small GTPases that cycle between an inactive GDP-bound state and an active GTP-bound state. In their active form these small GTPases can bind to certain downstream effectors and thereby exert their biological effects. The region within downstream effectors that mediates Rap1/2 binding is structurally conserved and referred to as the Ras binding domain (RBD) or Ras associating domain (RA).

Iwasa H et al. (2013) Exp Cell Res "Characterization of RSF-1, the Caenorhabditis elegans homolog of the Ras-association domain family protein 1."

Hata Y, Ikeda M, Iwasa H, Kuroyanagi H, Nakagawa K, Maimaiti S

[Exp Cell Res, 2013]

Mammals have 10 RASSF proteins, which are characterized by the Ras-association (RA) domain. Among them, RASSF1 to RASSF6 have the Salvador/RASSF/Hippo (SARAH) domain and form the subclass C-terminal RASSF proteins. Drosophila genome has a single C-terminal RASSF, dRASSF. All these RASSF proteins are related to the tumor suppressive Hippo pathway, and are considered to function as tumor suppressors. Caenorhabditis elegans T24F1.3 encodes a protein with the RA and the SARAH domains. The amino acid sequences are 40% and 55% similar to those of RASSF1 in the RA and the SARAH domains, respectively. We have characterized T24F1.3 gene product and named it RSF-1 as RASSF1 homolog. RSF-1 is widely expressed in epithelial cells. About 14% rsf-1 mutants exhibit defects in embryonal morphogenesis and the actin disorganization. The combinatorial synthetic lethal analysis demonstrates that the lethality is enhanced to more than 80% in rsf-1 mutants with the WASP-family verprolin homologous protein complex-related gene depletions and corroborates the implication of RSF-1 in the regulation of actin cytoskeleton. In rsf-1 mutants, the structures of muscle actin are preserved, but the swimming ability is impaired. Although we could not detect the direct physical interaction of LET-60 with RSF-1, rsf-1 mutants suppress the multivulva phenotype of the active let-60 mutants, suggesting that rsf-1 genetically interacts with the Ras signaling.

Wang, Juan et al. (2017) International Worm Meeting "Biogenesis and Function of Social Extracellular Vesicles (EVs)."

Barr, Maureen, Wang, Juan, Silva, Malan

[International Worm Meeting, 2017]

Extracellular vesicles are emerging as an important aspect of intercellular communication by delivering a parcel of proteins, lipids even nucleic acids to specific target cells over short or long distances (Maas 2017). A subset of C. elegans ciliated neurons release EVs to the environment and elicit changes in male behaviors in a cargo-dependent manner (Wang 2014, Silva 2017). Our studies raise many questions regarding these social communicating EV devices. Why is the cilium the donor site? What mechanisms control ciliary EV biogenesis? How are bioactive functions encoded within EVs? EV detection is a challenge and obstacle because of their small size (100nm). However, we possess the first and only system to visualize and monitor GFP-tagged EVs in living animals in real time. We are using several approaches to define the properties of an EV-releasing neuron (EVN) and to decipher the biology of ciliary-released EVs. To identify mechanisms regulating biogenesis, release, and function of ciliary EVs we took an unbiased transcriptome approach by isolating EVNs from adult worms and performing RNA-seq. We identified 335 significantly upregulated genes, of which 61 were validated by GFP reporters as expressed in EVNs (Wang 2015). By characterizing components of this EVN parts list, we discovered new components and pathways controlling EV biogenesis, EV shedding and retention in the cephalic lumen, and EV environmental release. We also identified cell-specific regulators of EVN ciliogenesis and are currently exploring mechanisms regulating EV cargo sorting. Our genetically tractable model can make inroads where other systems have not, and advance frontiers of EV knowledge where little is known. Maas, S. L. N., Breakefield, X. O., & Weaver, A. M. (2017). Trends in Cell Biology. Silva, M., Morsci, N., Nguyen, K. C. Q., Rizvi, A., Rongo, C., Hall, D. H., & Barr, M. M. (2017). Current Biology. Wang, J., Kaletsky, R., Silva, M., Williams, A., Haas, L. A., Androwski, R. J., Landis JN, Patrick C, Rashid A, Santiago-Martinez D, Gravato-Nobre M, Hodgkin J, Hall DH, Murphy CT, Barr, M. M. (2015).Current Biology. Wang, J., Silva, M., Haas, L. A., Morsci, N. S., Nguyen, K. C. Q., Hall, D. H., & Barr, M. M. (2014). Current Biology.