A heterogeneous mixture of F-series prostaglandins promotes sperm guidance in the Caenorhabditis elegans reproductive tract.

The mechanisms that guide motile sperm through the female reproductive tract to oocytes are not well understood. We have shown that Caenorhabditis elegans oocytes synthesize sperm guiding F-series prostaglandins from polyunsaturated fatty acid (PUFA) precursors provided in yolk lipoprotein complexes. Here we use genetics and electrospray ionization tandem mass spectrometry to partially delineate F-series prostaglandin metabolism pathways. We show that omega-6 and omega-3 PUFAs, including arachidonic and eicosapentaenoic acids, are converted into more than 10 structurally related F-series prostaglandins, which function collectively and largely redundantly to promote sperm guidance. Disruption of omega-3 PUFA synthesis triggers compensatory up-regulation of prostaglandins derived from omega-6 PUFAs. C. elegans F-series prostaglandin synthesis involves biochemical mechanisms distinct from those in mammalian cyclooxygenase-dependent pathways, yet PGF(2α) stereoisomers are still synthesized. A comparison of F-series prostaglandins in C. elegans and mouse tissues reveals shared features. Finally, we show that a conserved cytochrome P450 enzyme, whose human homolog is implicated in Bietti's Crystalline Dystrophy, negatively regulates prostaglandin synthesis. These results support the model that multiple cyclooxygenase-independent prostaglandins function together to promote sperm motility important for fertilization. This cyclooxygenase-independent pathway for F-series synthesis may be conserved.

Driver mutation zygosity is a critical factor in predicting clonal hematopoiesis transformation risk.

Clonal hematopoiesis (CH) can be caused by either single gene mutations (eg point mutations in JAK2 causing CHIP) or mosaic chromosomal alterations (e.g., loss of heterozygosity at chromosome 9p). CH is associated with a significantly increased risk of hematologic malignancies. However, the absolute rate of transformation on an annualized basis is low. Improved prognostication of transformation risk is urgently needed for routine clinical practice. We hypothesized that the co-occurrence of CHIP and mCAs at the same locus (e.g., transforming a heterozygous JAK2 CHIP mutation into a homozygous mutation through concomitant loss of heterozygosity at chromosome 9) might have important prognostic implications for malignancy transformation risk. We tested this hypothesis using our discovery cohort, the UK Biobank (n = 451,180), and subsequently validated it in the BioVU cohort (n = 91,335). We find that individuals with a concurrent somatic mutation and mCA were at significantly increased risk of hematologic malignancy (for example, In BioVU cohort incidence of hematologic malignancies is higher in individuals with co-occurring JAK2 V617F and 9p CN-LOH; HR = 54.76, 95% CI = 33.92-88.41, P < 0.001 vs. JAK2 V617F alone; HR = 44.05, 95% CI = 35.06-55.35, P < 0.001). Currently, the 'zygosity' of the CHIP mutation is not routinely reported in clinical assays or considered in prognosticating CHIP transformation risk. Based on these observations, we propose that clinical reports should include 'zygosity' status of CHIP mutations and that future prognostication systems should take mutation 'zygosity' into account.

Insulin/FOXO signaling regulates ovarian prostaglandins critical for reproduction.

Abnormalities in insulin/IGF-1 signaling are associated with infertility, but the molecular mechanisms are not well understood. Here we use liquid chromatography with electrospray ionization tandem mass spectrometry to show that the C. elegans insulin/FOXO pathway regulates the metabolism of locally acting lipid hormones called prostaglandins. C. elegans prostaglandins are synthesized without prostaglandin G/H synthase homologs, the targets of nonsteroidal anti-inflammatory drugs. Our results support the model that insulin signaling promotes the conversion of oocyte polyunsaturated fatty acids (PUFAs) into F-series prostaglandins that guide sperm to the fertilization site. Reduction in insulin signaling activates DAF-16/FOXO, which represses the transcription of germline and intestinal genes required to deliver PUFAs to oocytes in lipoprotein complexes. Nutritional and neuroendocrine cues target this mechanism to control prostaglandin metabolism and reproductive output. Prostaglandins may be conserved sperm guidance factors and widespread downstream effectors of insulin actions that influence both reproductive and nonreproductive processes.