Leydig, Zachary et al. (2021) International Worm Meeting "An Exploration of the protein FIGL-1 in the Caenorhabditis elegans Germline and Insights into its role in Homologous Recombination"

Yanowitz, Judith, Leydig, Zachary

[International Worm Meeting, 2021]

Repair of damaged DNA is crucial for the survival of both the individual organism and species. Double-strand breaks (DSB) are the most cytotoxic lesions. Homologous recombination (HR) is a high fidelity DSB repair pathway that relies on an undamaged homologous template. HR is especially important during meiosis prophase I, as it is a pathway that can repair programmed DSBs as crossovers (COs). CO homeostasis is a process that prevents either too few or too many COs between homologous chromosomes and without it, genome instability may ensue. In part, CO homeostasis is achieved by the mutual antagonism between HR/CO-promoting and HR/CO-inhibiting factors. The recombinase RAD-51 is central to HR as it coats the ssDNA filament to promote strand exchange. The anti-recombinase, FIGL-1 (Fidgetin-like protein 1), was shown in humans, mice, and plants to antagonize HR by directly interacting with RAD-51. Studies of how figl-1 functions in the germ line of Caenorhabditis elegans have been lacking in part because knockout of figl-1 is embryonic lethal. To determine if the interactions between RAD-51 and FIGL-1 are conserved in worms, I have been performing a yeast two-hybrid (Y2H) with the full-length proteins. If an interaction exists, interaction motifs will be mapped through a series of amino acid deletions and substitutions. It will be particularly interesting to determine whether the partially conserved FIGL1-RAD51 binding domain (FRBD) functions similarly in figl-1. CRISPR-Cas9 genome editing will be employed to introduce the mapped mutations into the figl-1 locus to observe the phenotypic effects in vivo. Additionally, plans to introduce targeted missense mutations into the highly conserved Walker A and B motifs, which are known to be important for ATP hydrolysis in FIGL-1, are underway. Interestingly, previous results have suggested that FIGL-1's ATP hydrolysis activity is independent of its anti-recombinase activity, suggesting that these mutations may result in separation-of-function mutants. Through these studies, specific domains within worm figl-1 will be scrutinized to shed more light on its function in the germ line as well its role in HR.

Zhang W et al. (2020) J Ethnopharmacol "Enzymatic Preparation of Crassostrea Oyster Peptides and Their Promoting Effect on Male Hormone Production."

Wei Y, Wang D, Xiao X, Zhai X, Zhang W, Guo K, Huang Z, Cao X, Wang Q

[J Ethnopharmacol, 2020]

ETHNOPHARMACOLOGICAL RELEVANCE: Crassostrea gigas Thunberg and other oysters have been traditionally used in China as folk remedies to invigorate the kidney and as natural aphrodisiacs to combat male impotence. AIM OF THE STUDY: Erectile dysfunction (ED) has become a major health problem for the global ageing population. The aim of this study is therefore to evaluate the effect of peptide-rich preparations from C. gigas oysters on ED and related conditions as increasing evidence suggests that peptides are important bioactive components of marine remedies and seafood. MATERIALS AND METHODS: Crassostrea oyster peptide (COP) preparations COP1, COP2 and COP3 were obtained from C. gigas oysters by trypsin, papain or sequential trypsin-papain digestion, respectively. The contents of testosterone, cyclic adenosine monophosphate (cAMP) and nitric oxide (NO) and the activity of nitric oxide synthase (NOS) in mice and/or cells were measured by enzyme-linked immunosorbent assays. Real-time PCR was used to assess the expression of genes associated with sex hormone secretion pathways. The model animal Caenorhabditis elegans was also used to analyze the gene expression of a conserved steroidogenic enzyme. In silico analysis of constituent peptides was performed using bioinformatic tools based on public databases. RESULTS: The peptide-rich preparation COP3, in which >95% peptides were <3000 Da, was found to increase the contents of male mouse serum testosterone and cAMP, both of which are known to play important roles in erectile function, and to increase the activity of mouse penile NOS, which is closely associated with ED. Further investigation using mouse Leydig-derived TM3 cells demonstrates that COP3 was able to stimulate the production of testosterone as well as NO, a pivotal mediator of penile erection. Real-time PCR analysis reveals that COP3 up-regulated the expression of Areg and Acvr2b, the genes known to promote sex hormone secretion, but not Fst, a gene involved in suppressing follicle-stimulating hormone release. Furthermore, COP3 was also shown to up-regulate the expression of let-767, a well-conserved C. elegans gene encoding a protein homologous to human 17--hydroxysteroid dehydrogenases. Preliminary bioinformatic analysis using the peptide sequences in COP3 cryptome identified 19 prospective motifs, each of which occurred in more than 10 peptides. CONCLUSIONS: In this paper, Crassostrea oyster peptides were prepared by enzymatic hydrolysis and were found for the first time to increase ED-associated biochemical as well as molecular biology parameters. These results may help to explain the ethnopharmacological use of oysters and provide an important insight into the potentials of oyster peptides in overcoming ED-related health issues.