A Systems Biology Approach Reveals the Role of a Novel Methyltransferase in Response to Chemical Stress and Lipid Homeostasis

Using small molecule probes to understand gene function is an attractive approach that allows functional characterization of genes that are dispensable in standard laboratory conditions and provides insight into the mode of action of these compounds. Using chemogenomic assays we previously identified yeast Crg1, an uncharacterized SAM-dependent methyltransferase, as a novel interactor of the protein phosphatase inhibitor cantharidin. In this study we used a combinatorial approach that exploits contemporary high-throughput techniques available in Saccharomyces cerevisiae combined with rigorous biological follow-up to characterize the interaction of Crg1 with cantharidin. Biochemical analysis of this enzyme followed by a systematic analysis of the interactome and lipidome of CRG1 mutants revealed that Crg1, a stress-responsive SAM-dependent methyltransferase, methylates cantharidin in vitro. Chemogenomic assays uncovered that lipid-related processes are essential for cantharidin resistance in cells sensitized by deletion of the CRG1 gene. Lipidome-wide analysis of mutants further showed that cantharidin induces alterations in glycerophospholipid and sphingolipid abundance in a Crg1-dependent manner. We propose that Crg1 is a small molecule methyltransferase important for maintaining lipid homeostasis in response to drug perturbation. This approach demonstrates the value of combining chemical genomics with other systems-based methods for characterizing proteins and elucidating previously unknown mechanisms of action of small molecule inhibitors

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Intravaginally applied oxytocin improves post-menopausal vaginal atrophy

OBJECTIVE: To explore the efficacy of local oxytocin for the treatment of post-menopausal vaginal atrophy. DESIGN: Double-blinded randomised controlled trial. SETTING: Healthy post-menopausal women in Stockholm, Sweden. PARTICIPANTS: Sixty four post-menopausal women between February and June 2012 at the Karolinska University Hospital Huddinge/Sweden. MAIN OUTCOME MEASURES: The efficacy of oxytocin for treatment of vaginal atrophy after seven weeks and cytological evaluation. RESULTS: The percentage of superficial cells in the vaginal smears and the maturation values were significantly increased after seven weeks of treatment with vagitocin 400 IU (p = 0.0288 and p = 0.0002, respectively). The vaginal pH decreased significantly after seven weeks of treatment with vagitocin 100 IU (p = 0.02). The scores of vaginal atrophy, according to the histological evaluation, were significantly reduced after administration of vagitocin 100 IU (p = 0.03). The thickness of the endometrium did not differ between the treatment and placebo groups after seven weeks of treatment. The symptom experienced as the most bothersome was significantly reduced after seven weeks of treatment in the women receiving vagitocin 400 IU compared to women in the placebo group (p = 0.0089). CONCLUSIONS: Treatment with intravaginally applied oxytocin could be an alternative to local estrogen treatment in women with post-menopausal vaginal atrophy