scholarly journals Oxidative Stress in the Male Germline: A Review of Novel Strategies to Reduce 4-Hydroxynonenal Production

Antioxidants ◽  
2018 ◽  
Vol 7 (10) ◽  
pp. 132 ◽  
Author(s):  
Jessica Walters ◽  
Geoffry De Iuliis ◽  
Brett Nixon ◽  
Elizabeth Bromfield
Keyword(s):  
Oxidative Stress ◽  
Germ Cells ◽  
Cell Function ◽  
De Novo ◽  
Protein Translation ◽  
Egg Recognition ◽  
Male Germline ◽  
New Strategy ◽  
Artery Disease ◽  
The Stability

Germline oxidative stress is intimately linked to several reproductive pathologies including a failure of sperm-egg recognition. The lipid aldehyde 4-hydroxynonenal (4HNE) is particularly damaging to the process of sperm-egg recognition as it compromises the function and the stability of several germline proteins. Considering mature spermatozoa do not have the capacity for de novo protein translation, 4HNE modification of proteins in the mature gametes has uniquely severe consequences for protein homeostasis, cell function and cell survival. In somatic cells, 4HNE overproduction has been attributed to the action of lipoxygenase enzymes that facilitate the oxygenation and degradation of ω-6 polyunsaturated fatty acids (PUFAs). Accordingly, the arachidonate 15-lipoxygenase (ALOX15) enzyme has been intrinsically linked with 4HNE production, and resultant pathophysiology in various complex conditions such as coronary artery disease and multiple sclerosis. While ALOX15 has not been well characterized in germ cells, we postulate that ALOX15 inhibition may pose a new strategy to prevent 4HNE-induced protein modifications in the male germline. In this light, this review focuses on (i) 4HNE-induced protein damage in the male germline and its implications for fertility; and (ii) new methods for the prevention of lipid peroxidation in germ cells.

scholarly journals Regulation of lysosome biogenesis by phosphoinositides and phagocytosis

2021 ◽  
Author(s):  
Christopher Choy
Keyword(s):  
Cell Function ◽  
De Novo ◽  
Mammalian Target Of Rapamycin ◽  
Protein Translation ◽  
Nuclear Accumulation ◽  
Fcγ Receptor ◽  
Lysosome Biogenesis ◽  
Transcription Factor Eb ◽  
Acidic Organelles ◽  
Pathogen Clearance

Lysosomes are acidic organelles responsible for molecular degradation, energy balance, and pathogen clearance. Consequently, lysosome dysfunction is linked to numerous diseases, including lysosome storage diseases. Notably, enhancing lysosome biogenesis ameliorates cell function and helps clear metabolites. The transcription factor EB (TFEB) is a master regulator of lysosome biogenesis, and thus a potential therapeutic target. Among known regulators of TFEB, the mammalian target of rapamycin complex 1 (mTORC1) is best understood. In nutrient-rich cells, mTORC1 is activated and represses TFEB by phosphorylation. Upon starvation, mTORC1 is inactivated and TFEB enters the nucleus, upregulating lysosomal gene expression to enhance cellular degradation for energy recovery. Numerous other TFEB-dependent pathways have been identified. We aim to understand how TFEB is regulated in two additional contexts: in lysosome enlargement during phosphatidylinositol 3,5-bisphosphate [PtdIns(3,5)P2] depletion and in phagocytosis. First, PtdIns(3,5)P2 is required for maintaining lysosome size by an incompletely understood mechanism. We hypothesized that TFEB-mediated lysosome biogenesis contributes de novo lysosomal material. Acute depletion of PtdIns(3,5)P2-synthesizing kinase PIKfyve induced TFEB nuclear accumulation. Despite increases in transcription, little to no protein translation was observed. Furthermore, tfeb-/-cells and cells blocked with cycloheximide were similar to wild-type cells, with regard to the number and size of lysosomes during PIKfyve inhibition cells, suggesting biosynthesis is not necessary for lysosome enlargement. However, TFEB still becomes active by an known mechanism. We show that TFEB nuclear localization during PIKfyve inhibition was not due to mTORC1 inactivation but may result from GSK3 inhibition. Secondly, phagocytosis allows immune cells to sequester potential pathogens by engulfing them into phagosomes. These phagosomes are then degraded by the lysosome. We postulated that phagocytosis would enhance TFEB-mediated lysosome biogenesis to promote pathogen killing. Fcγ receptor-mediated phagocytosis activated TFEB and increased biosynthesis of select lysosomal genes, augmenting existing lysosomes and enhancing proteolysis. To understand how TFEB was activated by the Fcγ receptor, we inhibited key signaling and trafficking mediators. Particle internalization, phagosome formation, and phagosome maturation appear to be necessary for TFEB activation. Overall, our work uncovers two additional mechanisms that may govern TFEBactivation.

scholarly journals Regulation of lysosome biogenesis by phosphoinositides and phagocytosis

2021 ◽  
Author(s):  
Christopher Choy
Keyword(s):  
Cell Function ◽  
De Novo ◽  
Mammalian Target Of Rapamycin ◽  
Protein Translation ◽  
Nuclear Accumulation ◽  
Fcγ Receptor ◽  
Lysosome Biogenesis ◽  
Transcription Factor Eb ◽  
Acidic Organelles ◽  
Pathogen Clearance

Lysosomes are acidic organelles responsible for molecular degradation, energy balance, and pathogen clearance. Consequently, lysosome dysfunction is linked to numerous diseases, including lysosome storage diseases. Notably, enhancing lysosome biogenesis ameliorates cell function and helps clear metabolites. The transcription factor EB (TFEB) is a master regulator of lysosome biogenesis, and thus a potential therapeutic target. Among known regulators of TFEB, the mammalian target of rapamycin complex 1 (mTORC1) is best understood. In nutrient-rich cells, mTORC1 is activated and represses TFEB by phosphorylation. Upon starvation, mTORC1 is inactivated and TFEB enters the nucleus, upregulating lysosomal gene expression to enhance cellular degradation for energy recovery. Numerous other TFEB-dependent pathways have been identified. We aim to understand how TFEB is regulated in two additional contexts: in lysosome enlargement during phosphatidylinositol 3,5-bisphosphate [PtdIns(3,5)P2] depletion and in phagocytosis. First, PtdIns(3,5)P2 is required for maintaining lysosome size by an incompletely understood mechanism. We hypothesized that TFEB-mediated lysosome biogenesis contributes de novo lysosomal material. Acute depletion of PtdIns(3,5)P2-synthesizing kinase PIKfyve induced TFEB nuclear accumulation. Despite increases in transcription, little to no protein translation was observed. Furthermore, tfeb-/-cells and cells blocked with cycloheximide were similar to wild-type cells, with regard to the number and size of lysosomes during PIKfyve inhibition cells, suggesting biosynthesis is not necessary for lysosome enlargement. However, TFEB still becomes active by an known mechanism. We show that TFEB nuclear localization during PIKfyve inhibition was not due to mTORC1 inactivation but may result from GSK3 inhibition. Secondly, phagocytosis allows immune cells to sequester potential pathogens by engulfing them into phagosomes. These phagosomes are then degraded by the lysosome. We postulated that phagocytosis would enhance TFEB-mediated lysosome biogenesis to promote pathogen killing. Fcγ receptor-mediated phagocytosis activated TFEB and increased biosynthesis of select lysosomal genes, augmenting existing lysosomes and enhancing proteolysis. To understand how TFEB was activated by the Fcγ receptor, we inhibited key signaling and trafficking mediators. Particle internalization, phagosome formation, and phagosome maturation appear to be necessary for TFEB activation. Overall, our work uncovers two additional mechanisms that may govern TFEBactivation.

scholarly journals MORC1 represses transposable elements in the mouse male germline

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
William A. Pastor ◽  
Hume Stroud ◽  
Kevin Nee ◽  
Wanlu Liu ◽  
Dubravka Pezic ◽  
...  
Keyword(s):  
Germ Cells ◽  
Dna Methyltransferase ◽  
De Novo ◽  
Cell Loss ◽  
Genetic Screens ◽  
Male Germline ◽  
Silent Genes ◽  
Localized Defects ◽  
Eukaryotic Organisms ◽  
Male Specific

Abstract The Microrchidia (Morc) family of GHKL ATPases are present in a wide variety of prokaryotic and eukaryotic organisms but are of largely unknown function. Genetic screens in Arabidopsis thaliana have identified Morc genes as important repressors of transposons and other DNA-methylated and silent genes. MORC1-deficient mice were previously found to display male-specific germ cell loss and infertility. Here we show that MORC1 is responsible for transposon repression in the male germline in a pattern that is similar to that observed for germ cells deficient for the DNA methyltransferase homologue DNMT3L. Morc1 mutants show highly localized defects in the establishment of DNA methylation at specific classes of transposons, and this is associated with failed transposon silencing at these sites. Our results identify MORC1 as an important new regulator of the epigenetic landscape of male germ cells during the period of global de novo methylation.

scholarly journals G-Quadruplex in the NRF2 mRNA 5′ Untranslated Region Regulates De Novo NRF2 Protein Translation under Oxidative Stress

2016 ◽  
Vol 37 (1) ◽  
Author(s):  
Sang C. Lee ◽  
Jack Zhang ◽  
Josh Strom ◽  
Danzhou Yang ◽  
Thai Nho Dinh ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Fate ◽  
Untranslated Region ◽  
De Novo ◽  
Tissue Injury ◽  
Elongation Factor ◽  
Protein Translation ◽  
General Measure ◽  
G Quadruplex ◽  
Nrf2 Protein

ABSTRACT Inhibition of protein synthesis serves as a general measure of cellular consequences of chemical stress. A few proteins are translated selectively and influence cell fate. How these proteins can bypass the general control of translation remains unknown. We found that low to mild doses of oxidants induce de novo translation of the NRF2 protein. Here we demonstrate the presence of a G-quadruplex structure in the 5′ untranslated region (UTR) of NRF2 mRNA, as measured by circular dichroism, nuclear magnetic resonance, and dimethylsulfate footprinting analyses. Such a structure is important for 5′-UTR activity, since its removal by sequence mutation eliminated H 2 O 2 -induced activation of the NRF2 5′ UTR. Liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based proteomics revealed elongation factor 1 alpha (EF1a) as a protein binding to the G-quadruplex sequence. Cells responded to H 2 O 2 treatment by increasing the EF1a protein association with NRF2 mRNA, as measured by RNA-protein interaction assays. The EF1a interaction with small and large subunits of ribosomes did not appear to change due to H 2 O 2 treatment, nor did posttranslational modifications, as measured by two-dimensional (2-D) Western blot analysis. Since NRF2 encodes a transcription factor essential for protection against tissue injury, our data have revealed a novel mechanism of cellular defense involving de novo NRF2 protein translation governed by the EF1a interaction with the G-quadruplex in the NRF2 5′ UTR during oxidative stress.

The Male Is Significantly Implicated as the Cause of Unexplained Infertility

2020 ◽  
Vol 38 (01) ◽  
pp. 003-020
Author(s):  
Robert John Aitken
Keyword(s):  
Oxidative Stress ◽  
Male Infertility ◽  
De Novo ◽  
Deep Understanding ◽  
Epigenetic Factors ◽  
De Novo Mutations ◽  
Male Factor ◽  
Male Germline ◽  
Broad Array ◽  
Ejaculation Frequency

AbstractMale infertility is recognized as a relatively common, complex condition, generated by a broad array of environmental and genetic factors. Historical reliance on the conventional semen profile has tended to underestimate the true contribution of “the male factor” to human infertility. This review highlights the importance of genetic and epigenetic factors in the etiology of male infertility, identifying a range of mutations responsible for primary testicular failure and impaired fertilizing potential. More than three quarters of all de novo mutations arise in the male germline via mechanisms that involve the inefficient or defective repair of DNA damage. Understanding the range of factors capable of creating genetic turmoil in the paternal germline is essential, if we are to gain a deep understanding of the causes of male infertility, rather than just the symptoms that characterize its presence. High levels of DNA fragmentation induced by oxidative stress are part of this equation. Oxidative stress is, in turn, driven by biological (age, ejaculation frequency, varicocele, infection), lifestyle (smoking, obesity), and environmental factors (heat, other forms of electromagnetic radiation, and toxins) that can impair the fertilizing potential of the spermatozoa and influence the incidence of spontaneous mutations that may cause infertility in the offspring.

scholarly journals Exposure to sevoflurane results in changes of transcription factor occupancy in sperm and inheritance of autism

2021 ◽  
Author(s):  
Hsiao-Lin V Wang ◽  
Samantha Forestier ◽  
Victor G Corces
Keyword(s):  
Germ Cells ◽  
Behavioral Problems ◽  
Animal Studies ◽  
De Novo ◽  
Germ Line ◽  
Autism Spectrum ◽  
General Anesthetics ◽  
General Anesthetic ◽  
Male Germline ◽  
Pregnant Mice

Abstract One in 54 children in the U.S. is diagnosed with Autism Spectrum Disorder (ASD). De novo germline and somatic mutations cannot account for all cases of ASD, suggesting that epigenetic alterations triggered by environmental exposures may be responsible for a subset of ASD cases. Human and animal studies have shown that exposure of the developing brain to general anesthetic (GA) agents can trigger neurodegeneration and neurobehavioral abnormalities but the effects of general anesthetics on the germ line have not been explored in detail. We exposed pregnant mice to sevoflurane during the time of embryonic development when the germ cells undergo epigenetic reprogramming and found that more than 38% of the directly exposed F1 animals exhibit impairments in anxiety and social interactions. Strikingly, 44–47% of the F2 and F3 animals, which were not directly exposed to sevoflurane, show the same behavioral problems. We performed ATAC-seq and identified more than 1200 differentially accessible sites in the sperm of F1 animals, 69 of which are also present in the sperm of F2 animals. These sites are located in regulatory regions of genes strongly associated with ASD, including Arid1b, Ntrk2, and Stmn2. These findings suggest that epimutations caused by exposing germ cells to sevoflurane can lead to ASD in the offspring, and this effect can be transmitted through the male germline inter and trans-generationally.

scholarly journals CD40/CD40L contributes to hypercholesterolemia-induced microvascular inflammation

2009 ◽  
Vol 296 (3) ◽  
pp. H689-H697 ◽  
Author(s):  
Karen Y. Stokes ◽  
LeShanna Calahan ◽  
Candiss M. Hamric ◽  
Janice M. Russell ◽  
D. Neil Granger
Keyword(s):  
Oxidative Stress ◽  
T Cells ◽  
T Cell ◽  
Blood Cell ◽  
Cell Function ◽  
Inflammatory Responses ◽  
Microvascular Dysfunction ◽  
Cd40 Ligand ◽  
Scid Mice ◽  
Endothelial Cell Function

Hypercholesterolemia is associated with phenotypic changes in endothelial cell function that lead to a proinflammatory and prothrombogenic state in different segments of the microvasculature. CD40 ligand (CD40L) and its receptor CD40 are ubiquitously expressed and mediate inflammatory responses and platelet activation. The objective of this study was to determine whether CD40/CD40L, in particular T-cell CD40L, contributes to microvascular dysfunction induced by hypercholesterolemia. Intravital microscopy was used to quantify blood cell adhesion in cremasteric postcapillary venules, endothelium-dependent vasodilation responses in arterioles, and microvascular oxidative stress in wild-type (WT) C57BL/6, CD40-deficient (−/−), CD40L−/−, or severe combined immune deficient (SCID) mice placed on a normal (ND) or high-cholesterol (HC) diet for 2 wk. WT-HC mice exhibited an exaggerated leukocyte and platelet recruitment in venules and impaired vasodilation responses in arterioles compared with ND counterparts. A deficiency of CD40, CD40L, or lymphocytes attenuated these responses to HC. The HC phenotype was rescued in CD40L−/− and SCID mice by a transfer of WT T cells. Bone marrow chimeras revealed roles for both vascular- and blood cell-derived CD40 and CD40L in the HC-induced vascular responses. Hypercholesterolemia induced an oxidative stress in both arterioles and venules of WT mice, which was abrogated by either CD40 or CD40L deficiency. The transfer of WT T cells into CD40L−/− mice restored the oxidative stress. These results implicate CD40/CD40L interactions between circulating cells and the vascular wall in both the arteriolar and venular dysfunction elicited by hypercholesterolemia and identify T-cell-associated CD40L as a key mediator of these responses.

scholarly journals Nanoencapsulation of Pomegranate Extract to Increase Stability and Potential Dermatological Protection

Pharmaceutics ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 271
Author(s):  
Lucía Yepes-Molina ◽  
José A. Hernández ◽  
Micaela Carvajal
Keyword(s):  
Oxidative Stress ◽  
Heavy Metals ◽  
Protective Effect ◽  
Uv Radiation ◽  
Entrapment Efficiency ◽  
Hacat Cells ◽  
Biotechnological Applications ◽  
Accelerated Stability ◽  
The Stability ◽  
Brassica Oleracea L

Pomegranate extract (PG-E) has been reported to exert a protective effect on the skin due to its antioxidant activity. Ingredients rich in phenolic compounds are unstable in extract solutions, and, therefore, the use of a suitable nanosystem to encapsulate this type of extract could be necessary in different biotechnological applications. Thus, we investigated the capacity of Brassica oleracea L. (cauliflower) inflorescence vesicles (CI-vesicles) to encapsulate PG-E and determined the stability and the antioxidant capacity of the system over time. In addition, the protective effect against UV radiation and heavy metals in HaCaT cells was also tested. The CI-vesicles had an entrapment efficiency of around 50%, and accelerated stability tests did not show significant changes in the parameters tested. The results for the HaCaT cells showed the non-cytotoxicity of the CI-vesicles containing PG-E and their protection against heavy metals (lead acetate and mercuric chloride) and UV-B radiation through a reduction of oxidative stress. The reduction of the percentage of deleted mtDNA (mtDNA4977, “common deletion”) in UV-treated HaCaT cells due to the presence of CI-vesicles containing PG-E indicated the mechanism of protection. Therefore, the effects of CI-vesicles loaded with PG-E against oxidative stress support their utilization as natural cosmeceuticals to protect skin health against external damage from environmental pollution and UV radiation.

scholarly journals Rational thermostabilisation of four-helix bundle dimeric de novo proteins

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shin Irumagawa ◽  
Kaito Kobayashi ◽  
Yutaka Saito ◽  
Takeshi Miyata ◽  
Mitsuo Umetsu ◽  
...  
Keyword(s):  
Protein Design ◽  
De Novo ◽  
Protein Complexes ◽  
Salt Bridge ◽  
Dynamics Simulation ◽  
Saturation Mutagenesis ◽  
Helix Bundle ◽  
Stable Mutant ◽  
Four Helix Bundle ◽  
The Stability

AbstractThe stability of proteins is an important factor for industrial and medical applications. Improving protein stability is one of the main subjects in protein engineering. In a previous study, we improved the stability of a four-helix bundle dimeric de novo protein (WA20) by five mutations. The stabilised mutant (H26L/G28S/N34L/V71L/E78L, SUWA) showed an extremely high denaturation midpoint temperature (Tm). Although SUWA is a remarkably hyperstable protein, in protein design and engineering, it is an attractive challenge to rationally explore more stable mutants. In this study, we predicted stabilising mutations of WA20 by in silico saturation mutagenesis and molecular dynamics simulation, and experimentally confirmed three stabilising mutations of WA20 (N22A, N22E, and H86K). The stability of a double mutant (N22A/H86K, rationally optimised WA20, ROWA) was greatly improved compared with WA20 (ΔTm = 10.6 °C). The model structures suggested that N22A enhances the stability of the α-helices and N22E and H86K contribute to salt-bridge formation for protein stabilisation. These mutations were also added to SUWA and improved its Tm. Remarkably, the most stable mutant of SUWA (N22E/H86K, rationally optimised SUWA, ROSA) showed the highest Tm (129.0 °C). These new thermostable mutants will be useful as a component of protein nanobuilding blocks to construct supramolecular protein complexes.

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