Maroney PA et al. (1996) RNA "Direct analysis of nematode cis- and trans-spliceosomes: a functional role for U5 snRNA in spliced leader addition trans-splicing and the identification of novel Sm snRNPs."

Yu YT, Nilsen TW, Jankowska M, Maroney PA

[RNA, 1996]

Most nuclear pre-mRNAs in nematodes are processed by both cis- and trans-splicing. In trans-splicing, the 5'' terminal exon, the spliced leader sequence (SL), is derived from a trans-splicing specific Sm snRNP, the SL RNP. Because U snRNPs are required cofactors for trans-splicing, and because this processing reaction proceeds via a two-step reaction pathway identical to that of cis-splicing, it has long been assumed that trans-splicing is catalyzed in a complex analogous to the cis-spliceosome. However, similarities or differences between cis- and trans-spliceosomes have not been established. In particular, the role of U5 snRNP in trans-splicing has been unclear. Here, we have used affinity selection to analyze the U snRNA constituents of nematode cis- and trans-spliceosomes. We find that U5 snRNP is an integral component of the trans-spliceosome and, using site-specific crosslinking, we show that U5 snRNP establishes specific Interactions with the SL RNA exon. We also identify two novel Sm snRNPs that are enriched in both cis- and trans-spliceosomes. Finally, we provide evidence that a SL RNP-containing multi-snRNP (SL, U4, U5, and U6 RNPs) may be a functional precursor in trans-spliceosome assembly.

Denker JA et al. (1996) RNA "Multiple requirements for nematode spliced leader RNP function in trans-splicing."

Yu YT, Denker JA, Kanost RA, Nilsen TW, Maroney PA

[RNA, 1996]

The 5'' exon donor in nematode trans-splicing, the SL RNA, is a small (approximately 100 nt) RNA that resembles cis-spliceosomal U snRNAs. Extensive analyses of the RNA sequence requirements for SL RNA function have revealed four essential elements, the core Sm binding site, three nucleotides immediately downstream of this site, a region of Stem-loop II, and a 5'' splice site. Although these elements are necessary and sufficient for SL RNA function in vitro, their respective roles in promoting SL RNA activity have not been elucidated. Furthermore, although it has been shown that assembly of the SL RNA into an Sm RNP is a prerequisite for function, the protein composition of the SL RNP has not been determined. Here, we have used oligoribonucleotide affinity to purify the SL RNP and find that it contains core Sm proteins as well as four specific proteins (175, 40, 30, and 28 kDa). Using in vitro assembly assays; we show that association of the 175- and 30-kDa SL-specific proteins correlates with SL RNP function in trans-splicing. Binding of these proteins depends upon the sequence of the core Sm binding site; SL RNAs containing the U1 snRNA Sm binding site assemble into Sm RNPs that contain core, but not SL-specific proteins. Furthermore, mutational and thiophosphate interference approaches reveal that both the primary nucleotide sequence and a specific phosphate oxygen within a segment of Stemloop II of the SL RNA are required for function. Finally, mutational activation of an unusual cryptic 5'' splice site within the SL sequence itself suggests that U5 snRNA may play a primary role in selecting and specifying the 5'' splice site in SL addition trans-splicing.

Hannon GJ et al. (1992) Science "Interaction of U6 snRNA with a sequence required for function of the nematode SL RNA in trans-splicing."

Maroney PA, Nilsen TW, Yu YT, Hannon GE, Hannon GJ

[Science, 1992]

Nematode trans-spliced leader (SL) RNAs are composed of two domains, an exon [the 22-nucleotide spliced leader] and a small nuclear RNA (snRNA)-like sequence. Participation in vitro of the spliced leader RNA in trans-splicing reactions is independent of the exon sequence or size and instead depends on features contained in the snRNA-like domain of the molecule. Chemical modification interference analysis has revealed that two short sequence elements in the snRNA-like domain are necessary for SL RNA activity. These elements are sufficient for such activity because when added to a 72-nucleotide fragment of a nematode U1 snRNA, this hybrid RNA could participate in trans-splicing reactions in vitro. One of the critical sequence elements may function by base-pairing with U6 snRNA, an essential U snRNA for both cis- and trans-splicing.

Yang ZZ et al. (2018) Free Radic Biol Med "Lonicera japonica extends lifespan and healthspan in Caenorhabditis elegans."

Wang HB, Cui XH, Liao DC, Yu YT, Yang ZZ, Lin HR

[Free Radic Biol Med, 2018]

Lonicera japonica (LJ) is widely used as the local medicine to improve body and prevent ills in China, but mechanisms of its heathy beneficial effects remain largely unclear. Here, we evaluated the anti-aging and healthspan promoting activities of 75% ethanol extract of LJ (LJ-E) in the animal model Caenorhabditis elegans. Our results showed that LJ-E (500g/mL) treatment enhanced the mean lifespan of worms by over 21.87% and significantly improved age-associated physiological functions in C. elegans. The 500g/mL concentration of LJ-E enhanced the survival rates under oxidative and thermal stresses, and decreased reactive oxygen species (ROS) levels and fat accumulation in the worms. Gene-specific mutant studies showed that LJ-E-mediated lifespan extension was dependent on mev-1, daf-2, daf-16, and hsf-1, but not eat-2 genes. LJ-E could upregulate stress-inducible genes, viz., hsp-16.2, sod-3 and mtl-1. Moreover, we found that the D1086.10 protein interacted with superoxide dismutase (SOD)-3 by functional protein association networks analysis according to RNA-sequencing results. It was confirmed that D1086.10 was needed to promote longevity, and positively regulated expression of sod-3 by using D1086.10 mutants. Furthermore, LJ-E significantly delayed amyloid -protein induced paralysis in CL4176 strain. Given the important role of autophagy in aging and protein homeostasis, we observed that LJ-E could remarkably increase the mRNA expression of autophagy gene bec-1 in CL4176 strain, and decrease expression of autophagy substrate p62 protein by more than 40.0% in BC12921 strain. Finally, we found that combination composed of three major compounds (54g/mL chlorogenic acid, 15g/mL 1,5-dicaffeoylquinic acid and 7.5g/mL 1,3-dicaffeoylquinic acid) of 500g/mL LJ-E could significantly delay paralysis in CL4176 worms caused by A toxicity, comparable to that of LJ-E. Overall, our study may have important implications in using Lonicera japonica to promote healthy aging and have a potency to design therapeutics for age-related diseases.

Chen XY et al. (2020) Biogerontology "Coix seed oil prolongs lifespan and enhances stress resistance in Caenorhabditis elegans."

Xuan LY, Wang HB, Chen XY, Liao DC, Wei CM, Yu YT, Li S

[Biogerontology, 2020]

Coix seed oil (CSO) has many beneficial effects, but there is limited research on its influence on the processes and mechanisms related to senescence. Here, we used Caenorhabditis elegans as an in vivo model to investigate CSO's bioeffects on longevity. CSO (1mg/mL) significantly extended the mean lifespan of C. elegans by over 22.79% and markedly improved stress resistance. Gene-specific mutant studies showed that the CSO-mediated increase in life expectancy was dependent on mev-1, hsf-1 and daf-16, but not daf-2. Furthermore, CSO significantly upregulated stress-inducible genes, including daf-16 and its downstream genes (sod-3, hsp-16.2 and gst-4). In addition, four major fatty acids, linoleic, oleic, palmitic and stearic, played leading roles in C. elegans' extended lifespan. Thus, CSO increased the life expectancy of, and enhanced the stress resistance in, C. elegans mainly through daf-16 and its downstream genes, but not through the insulin/insulin-like growth factor 1 signaling pathway.

Von Stetina SE et al. (2015) Dev Biol "PAR-6, but not E-cadherin and -integrin, is necessary for epithelial polarization in C. elegans."

Von Stetina SE, Mango SE

[Dev Biol, 2015]

Cell polarity is a fundamental characteristic of epithelial cells. Classical cell biological studies have suggested that establishment and orientation of polarized epithelia depend on outside-in cues that derive from interactions with either neighboring cells or the substratum (Akhtar and Streuli, 2013; Chen and Zhang, 2013; Chung and Andrew, 2008; McNeill et al., 1990; Nejsum and Nelson, 2007; Nelson et al., 2013; Ojakian and Schwimmer, 1994; Wang et al., 1990; Yu et al., 2005). This paradigm has been challenged by examples of epithelia generated in the absence of molecules that mediate cell-cell or cell-matrix interactions, notably E-cadherin and integrins (Baas et al., 2004; Choi et al., 2013; Costa et al., 1998; Harris and Peifer, 2004; Raich et al., 1999; Roote and Zusman, 1995; Vestweber et al., 1985; Williams and Waterston, 1994; Wu et al., 2009). Here we explore an alternative hypothesis, that cadherins and integrins function redundantly to substitute for one another during epithelium formation (Martinez-Rico et al., 2010; Ojakian et al., 2001; Rudkouskaya et al., 2014; Weber et al., 2011). We use C. elegans, which possesses a single E-cadherin (Costa et al., 1998; Hardin et al., 2013; Tepass, 1999) and a single -integrin (Gettner et al., 1995; Lee et al., 2001), and analyze the arcade cells, which generate an epithelium late in embryogenesis (Portereiko and Mango, 2001; Portereiko et al., 2004), after most maternal factors are depleted. Loss of E-cadherin(HMR-1) in combination with -integrin(PAT-3) had no impact on the onset or formation of the arcade cell epithelium, nor the epidermis or digestive tract. Moreover, B-integrin(PAT-3) was not enriched at the basal surface of the arcades, and the candidate PAT-3 binding partner -laminin(LAM-1) was not detected until after arcade cell polarity was established and exhibited no obvious polarity defect when mutated. Instead, the polarity protein par-6 (Chen and Zhang, 2013; Watts et al., 1996) was required to polarize the arcade cells, and par-6 mutants exhibited mislocalized or absent apical and junctional proteins. We conclude that the arcade cell epithelium polarizes by a PAR-6-mediated pathway that is independent of E-cadherin, -integrin and -laminin.