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Although lipid metabolism is thought to be important for the proper maturation and function of spermatozoa, the molecular mechanisms that underlie this dynamic process in the gonads remains incompletely understood. Here, we show that group III phospholipase [A.sup.2] ([sPLA.sup.2]-III), a member of the secreted phospholipase [A.sup.2] ([sPLA.sup.2]) family, is expressed in the mouse proximal epididymal epithelium and that targeted disruption of the gene encoding this protein (PlA2g3) leads to defects in sperm maturation and fertility. Although testicular spermatogenesis in [PlA2g3.sup.[-/-]] mice was grossly normal, spermatozoa isolated from the cauda epididymidis displayed hypomotility, and their ability to fertilize intact eggs was markedly impaired. Transmission EM further revealed that epididymal spermatozoa in [PlA2g3.sup.[-/-]] mice had both flagella with abnormal axonemes and aberrant acrosomal structures. During epididymal transit, phosphatidylcholine in the membrane of [PlA2g3.sup.[+/+]] sperm underwent a dramatic shift in its acyl groups from oleic, linoleic, and arachidonic acids to docosap-entaenoic and docosahexaenoic acids, whereas this membrane lipid remodeling event was compromised in sperm from [PlA2g3.sup.[-/-]] mice. Moreover, the gonads of [PlA2g3.sup.[-/-]] mice contained less 12/15-lipoxygenase metabolites than did those of [PlA2g3.sup.[+/+]] mice. Together, our results reveal a role for the atypical [sPLA.sup.2] family member [sPLA.sup.2]-III in epididymal lipid homeostasis and indicate that its perturbation may lead to sperm dysfunction., Introduction The male reproductive system consists of a series of organs rhar acr together to produce and deliver functional spermatozoa into the female reproductive tract. After the complex differentiation process [...]

Ejaculated mammalian sperm must undergo a maturation process called capacitation before they are able to fertilize an egg. Several studies have suggested a role for members of the secreted phospholipase [A.sub.2] ([sPLA.sub.2]) family in capacitation, acrosome reaction (AR), and fertilization, but the molecular nature of these enzymes and their specific roles have remained elusive. Here, we have demonstrated that mouse group X [sPLA.sub.2] (mGX) is the major enzyme present in the acrosome of spermatozoa and that it is released in an active form during capacitation through spontaneous AR. mGX-deficient male mice produced smaller litters than wild-type male siblings when crossed with mGX-deficient females. Further analysis revealed that spermatozoa from mGX-deficient mice exhibited lower rates of spontaneous AR and that this was associated with decreased in vitro fertilization (IVF) efficiency due to a drop in the fertilization potential of the sperm and an increased rate of aborted embryos. Treatment of sperm with [sPLA.sub.2] inhibitors and antibodies specific for mGX blocked spontaneous AR of wild-type sperm and reduced IVF success. Addition of lysophosphatidylcholine, a catalytic product of mGX, overcame these deficiencies. Finally, recombinant mGX triggered AR and improved IVF outcome. Taken together, our results highlight a paracrine role for mGX during capacitation in which the enzyme primes sperm for efficient fertilization and boosts premature AR of a likely phospholipid-damaged sperm subpopulation to eliminate suboptimal sperm from the pool available for fertilization., Introduction Spermatogenesis within the testis leads to the production of morphologically mature sperm that are still functionally immature, immotile, and incompetent for fertilization. Before fertilization, sperm should undergo two major [...]

Infection with the gastric pathogen Helicobacter pylori (H. pylori) causes chronic gastritis, peptic ulcer, and gastric adenocarcinoma. These diseases are associated with production of reactive oxygen species (ROS) from infiltrated macrophages and neutrophiles in inflammatory sites. Metallothionein (MT) is a low-molecular-weight, cysteine-rich protein that can act not only as a metal-binding protein, but also as a ROS scavenger. In the present study, we examined the role of MT in the protection against H. pylori-induced gastric injury using MT-null mice. Female MT-null and wild-type mice were challenged with H. pylori SS1 strain, and then histological changes were evaluated with the updated Sydney grading system at 17 and 21 wk after challenge. Although the colonization efficiency of H. pylori was essentially the same for MT-null and wild-type mice, the scores of activity of inflammatory cells were significantly higher in MT-null mice than in wild-type mice at 17 wk after challenge. Histopathological examination revealed erosive lesions accompanied by infiltration of inflammatory cells in the infected MT-null mice but not in wild-type mice. Furthermore, activation of NF-KB and expression of NF-KB-mediated chemokines such as macrophage inflammatory protein-IoL and monocytes chemoattractant protein-1 in gastric cells were markedly higher in MT-null mice than in wild-type mice. These results suggest that MT in the gastric mucosa might play an important role in the protection against H. pylori-induced gastric ulceration. gastric ulcer; reactive oxygen species; NF-KB; chemokine

Chemokines are secreted proteins that regulate cell migration and are involved in inflammatory and immune responses. Here, we sought to define the functional crosstalk between the lipid signaling and chemokine signaling. We obtained evidence that the induction of some chemokines is regulated by group VIA calcium‐independent phospholipase A2β (iPLA2β) in IL‐1β‐stimulated rat fibroblastic 3Y1 cells. Treatment of 3Y1 cells with IL‐1β elicited an increased release of chemotactic factor(s) for monocytic THP‐1 cells into culture medium in a time‐dependent manner. Inhibitor studies revealed that an intracellular PLA2 inhibitor, arachidonoyl trifluoromethyl ketone (AACOCF3), but not the cyclooxygenase inhibitor indomethacin, attenuated the release of chemotactic factor(s). The chemotactic activity was inactivated by treatment with either heat or proteinase K, suggesting this chemotactic factor(s) is a proteinaceous factor(s). We purified the chemotactic factor(s) from the conditioned medium of IL‐1β‐stimulated 3Y1 cells using a heparin column and identified several chemokines, including CCL2 and CXCL10. The inducible expressions of CCL2 and CXCL10 were significantly attenuated by pretreatment with AACOCF3. Gene silencing using siRNA revealed that the inductions of CCL2 and CXCL10 were attenuated by iPLA2β knockdown. Additionally, the transcriptional activation of nuclear factor of activated T‐cell proteins (NFATs), but not nuclear factor‐κB, by IL‐1β stimulation was markedly attenuated by the iPLA2 inhibitor bromoenol lactone, and NFATc4 knockdown markedly attenuated the IL‐1β‐induced expression of both CCL2 and CXCL10. Collectively, these results indicated that iPLA2β plays roles in IL‐1β‐induced chemokine expression, in part via NFATc4 signaling. [ABSTRACT FROM AUTHOR]