EVA1A regulates hematopoietic stem cell regeneration via ER-mitochondria mediated apoptosis.

Excessive protein synthesis upon enhanced cell proliferation frequently results in an increase of unfolded or misfolded proteins. During hematopoietic regeneration, to replenish the hematopoietic system, hematopoietic stem cells (HSCs) are activated and undergo a rapid proliferation. But how the activated HSCs respond to the proliferation pressure is still ambiguous; The proper control of the functional reservoir in the activated HSCs remains poorly understood. Here, we show a significant upregulation of EVA1A protein associated with the increase of ER stress during hematopoietic regeneration. Deletion of Eva1a significantly enhances the regeneration capacity of HSCs by inhibiting the ER stress-induced apoptosis. Mechanistically, the expression of EVA1A protein was upregulated by CHOP, and thereby promoted the ER-mitochondria interlinking via MCL1, which resulted in mitochondria-mediated apoptosis. These findings reveal a pathway for ER stress responses of HSCs by the EVA1A mediated apoptosis, which play an important role in HSCs regeneration.

mTORC2 Facilitates Liver Regeneration Through Sphingolipid-Induced PPAR-α-Fatty Acid Oxidation.

BACKGROUND & AIMS: During liver regeneration after partial hepatectomy, the function and metabolic pathways governing transient lipid droplet accumulation in hepatocytes remain obscure. Mammalian target of rapamycin 2 (mTORC2) facilitates de novo synthesis of hepatic lipids. Under normal conditions and in tumorigenesis, decreased levels of triglyceride (TG) and fatty acids (FAs) are observed in the mTORC2-deficient liver. However, during liver regeneration, their levels increase in the absence of mTORC2. METHODS: Rictor liver-specific knockout and control mice underwent partial hepatectomy, followed by measurement of TG and FA contents during liver regeneration. FA metabolism was evaluated by analyzing the expression of FA metabolism-related genes and proteins. Intraperitoneal injection of the peroxisome proliferator-activated receptor α (PPAR-α) agonist, p53 inhibitor, and protein kinase B (AKT) activator was performed to verify the regulatory pathways involved. Lipid mass spectrometry was performed to identify the potential PPAR-α activators. RESULTS: The expression of FA metabolism-related genes and proteins suggested that FAs are mainly transported into hepatocytes during liver regeneration. The PPAR-α pathway is down-regulated significantly in the mTORC2-deficient liver, resulting in the accumulation of TGs. The PPAR-α agonist WY-14643 rescued deficient liver regeneration and survival in mTORC2-deficient mice. Furthermore, lipidomic analysis suggested that mTORC2 deficiency substantially reduced glucosylceramide (GluCer) content. GluCer activated PPAR-α. GluCer treatment in vivo restored the regenerative ability and survival rates in the mTORC2-deficient group. CONCLUSIONS: Our data suggest that FAs are mainly transported into hepatocytes during liver regeneration, and their metabolism is facilitated by mTORC2 through the GluCer-PPAR-α pathway, thereby establishing a novel role for mTORC2 in lipid metabolism.

Association of Human Whole Blood NAD+ Contents With Aging.

Background: NAD+, nicotinamide adenine dinucleotide, is mostly described to associate with the aging process. We aimed to investigate the association between human whole blood NAD+ contents and aging in a relative large-scale community-based population and further to address the gender impact on this association. Methods: We recruited 1,518 participants aged over 18 years old and free of cardiovascular and any type of cancer from the Jidong community from 2019 to 2020. Whole blood NAD+ level was measured by cycling assay and LC-mass spectroscopy assay. The chronological age and clinical data were collected using standard questionnaires. The participants were divided into five groups according to their chronological age. General liner regression model was performed to analyze the association between NAD+ contents and aging. In addition, we also conducted subgroup analysis by gender. Results: The mean age of included 1,518 participants was 43.0 years, and 52.6% of them were men. The average levels of whole blood NAD+ of total participants was 33.0 ± 5.5 µmol/L. The whole blood NAD+ contents in men were significantly higher than that in women (34.5 vs. 31.3 µmol/L). There was significant difference in the meat diet among NAD+ quartile groups (p = 0.01). We observed a decline trend of NAD+ contents with aging before 50 years in total participants with significant level in 40-49 years old group (ß coefficients with 95% confidence interval (95% CI): -1.12 (-2.18, -0.06)), while this trend disappeared after the 50 years. In addition, this association was significantly altered by gender (p for interaction = 0.003). In men, as compared with ≤29 years group, adjusted ß coefficient decreased with aging but was only significant in the ≥60 year group (ß,-2.16; 95% CI, -4.16 to -0.15). In females, the level of whole blood NAD+ did not significantly differ among five age groups and without the trend as males. Conclusions: Association of whole blood NAD+ contents with aging significantly differed in males and females. The loss of blood NAD+ with aging only was observed in males, especially in the male middle-aged population. It is crucial to consider the gender difference in further NAD+ related studies in the future.

Association between NAD+ levels and anaemia among women in community-based study.

Nicotinamide adenine dinucleotide (NAD+ ) level is the protective factor of cardiovascular diseases (CVDs). In addition, anaemia is a risk factor of adverse cardiovascular outcomes in women. However, there are limited data about the association between NAD+ and anaemia. The aim of this study was to evaluate association of NAD+ with anaemia among women. A total of 727 females from Jidong community were included in the current analysis. NAD+ levels were tested by the cycling assay and HPLC assay using whole blood samples. Anaemia was determined by haemoglobin (Hb) concentration, and the subtypes of anaemia were further defined according to mean corpuscular volume (MCV) in blood. Multivariable logistic analysis was used to analyse the association between NAD+ levels and anaemia or its subtypes. The mean age of recruited subjects was 42.7 years. The proportion of anaemia by NAD+ levels quartiles were 19.7% (35/178), 4.8% (9/189), 3.4% (6/178) and 2.7% (5/182). Haematological parameters including haemoglobin (Hb), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC) and red blood count (RBC) increased over NAD+ quartiles. Red cell volume distribution width (RDW) decreased over NAD+ quartiles. Compared with the lowest quartile of NAD+ levels (<27.6µM), the adjusted odds ratios with 95% confidence intervals of the top quartile were 0.15 (0.06-0.41) for anaemia, 0.05 (0.01-0.36) for microcytic anaemia and 0.37 (0.10-1.36) for normocytic anaemia respectively. Higher NAD+ levels were significantly associated with lower prevalence of anaemia among women, especially microcytic anaemia and normocytic anaemia. Haematological parameters might serve as a predictor of the blood NAD+ levels.

C/EBP homologous protein deficiency enhances hematopoietic stem cell function via reducing ATF3/ROS-induced cell apoptosis.

Hematopoietic stem cells (HSCs) reside in a quiescent niche to reserve their capacity of self-renewal. Upon hematopoietic injuries, HSCs enter the cell cycle and encounter protein homeostasis problems caused by accumulation of misfolded proteins. However, the mechanism by which protein homeostasis influences HSC function and maintenance remains poorly understood. Here, we show that C/EBP homologous protein (CHOP), demonstrated previously to induces cell death upon unfolded protein response (UPR), plays an important role in HSCs regeneration. CHOP-/- mice showed normal hematopoietic stem and progenitor cell frequencies in steady state. However, when treated with 5-FU, CHOP deficiency resulted in higher survival rates, associated with an increased number of HSCs and reduced level of apoptosis. In serial competitive transplantation experiments, CHOP-/- HSCs showed a dramatic enhancement of repopulation ability and a reduction of protein aggresomes. Mechanistically, CHOP deletion causes reduced ATF3 expression and further leads to decreased protein aggregation and ROS. In addition, CHOP-/- HSCs exhibited an increased resistance to IR-induced DNA damage and improved HSCs homeostasis and function in telomere dysfunctional (G3Terc-/- ) mice. In summary, these findings disclose a new role of CHOP in the regulation of the HSCs function and homeostasis through reducing ATF3 and ROS signaling.

APP/PS1 Gene-Environment Noise Interaction Aggravates AD-like Neuropathology in Hippocampus Via Activation of the VDAC1 Positive Feedback Loop.

BACKGROUND: Environmental risk factors, including environmental noise stress, and genetic factors, have been associated with the occurrence and development of Alzheimer's disease (AD). However, the exact role and mechanism of AD-like pathology induced by environment-gene interactions between environmental noise and APP/PS1 gene remain elusive. METHODS: Herein, we investigated the impact of chronic noise exposure on AD-like neuropathology in APP/PS1 transgenic mice. The Morris water maze (MWM) task was conducted to evaluate AD-like changes. The hippocampal phosphorylated Tau, amyloid-ß (Aß), and neuroinflammation were assessed. We also assessed changes in positive feedback loop signaling of the voltage-dependent anion channel 1 (VDAC1) to explore the potential underlying mechanism linking AD-like neuropathology to noise-APP/PS1 interactions. RESULTS: Long-term noise exposure significantly increased the escape latency and the number of platform crossings in the MWM task. The Aß overproduction was induced in the hippocampus of APP/PS1 mice, along with the increase of Tau phosphorylation at Ser396 and Thr231 and the increase of the microglia and astrocytes markers expression. Moreover, the VDAC1-AKT (protein kinase B)-GSK3ß (glycogen synthase kinase 3 beta)-VDAC1 signaling pathway was abnormally activated in the hippocampus of APP/PS1 mice after noise exposure. CONCLUSION: Chronic noise exposure and APP/PS1 overexpression may synergistically exacerbate cognitive impairment and neuropathological changes that occur in AD. This interaction may be mediated by the positive feedback loop of the VDAC1-AKT-GSK3ß-VDAC1 signaling pathway.

Protein S-nitrosylation regulates proteostasis and viability of hematopoietic stem cell during regeneration.

Hematopoietic stem cells (HSCs) regenerate blood cells upon hematopoietic injuries. During homeostasis, HSCs are maintained in a low reactive oxygen species (ROS) state to prevent exhaustion. However, the role of nitric oxide (NO) in controlling HSC regeneration is still unclear. Here, we find increased NO during HSC regeneration with an accumulation of protein aggregation. S-nitrosoglutathione reductase (GSNOR)-deleted HSCs exhibit a reduced reconstitution capacity and loss of self-renewal after chemotherapeutic injury, which is resolved by inhibition of NO synthesis. Deletion of GSNOR enhances protein S-nitrosylation, resulting in an accumulation of protein aggregation and activation of unfolded protein response (UPR). Treatment of taurocholic acid (TCA), a chemical chaperone, rescues the regeneration defect of Gsnor-/- HSCs after 5-fluorouracil (5-FU) treatment. Deletion of C/EBP homologous protein (Chop) restores the reconstitution capacity of Gsnor-/- HSCs. These findings establish a link between S-nitrosylation and protein aggregation in HSC in the context of blood regeneration.

Fine-Tuning of PGC1α Expression Regulates Cardiac Function and Longevity.

RATIONALE: PGC1α (peroxisome proliferator-activated receptor gamma coactivator 1α) represents an attractive target interfering bioenergetics and mitochondrial homeostasis, yet multiple attempts have failed to upregulate PGC1α expression as a therapy, for instance, causing cardiomyopathy. OBJECTIVE: To determine whether a fine-tuning of PGC1α expression is essential for cardiac homeostasis in a context-dependent manner. METHODS AND RESULTS: Moderate cardiac-specific PGC1α overexpression through a ROSA26 locus knock-in strategy was utilized in WT (wild type) mice and in G3Terc-/- (third generation of telomerase deficient; hereafter as G3) mouse model, respectively. Ultrastructure, mitochondrial stress, echocardiographic, and a variety of biological approaches were applied to assess mitochondrial physiology and cardiac function. While WT mice showed a relatively consistent PGC1α expression from 3 to 12 months old, age-matched G3 mice exhibited declined PGC1α expression and compromised mitochondrial function. Cardiac-specific overexpression of PGC1α (PGC1αOE) promoted mitochondrial and cardiac function in 3-month-old WT mice but accelerated cardiac aging and significantly shortened life span in 12-month-old WT mice because of increased mitochondrial damage and reactive oxygen species insult. In contrast, cardiac-specific PGC1α knock in in G3 (G3 PGC1αOE) mice restored mitochondrial homeostasis and attenuated senescence-associated secretory phenotypes, thereby preserving cardiac performance with age and extending health span. Mechanistically, age-dependent defect in mitophagy is associated with accumulation of damaged mitochondria that leads to cardiac impairment and premature death in 12-month-old WT PGC1αOE mice. In the context of telomere dysfunction, PGC1α induction replenished energy supply through restoring the compromised mitochondrial biogenesis and thus is beneficial to old G3 heart. CONCLUSIONS: Fine-tuning the expression of PGC1α is crucial for the cardiac homeostasis because the balance between mitochondrial biogenesis and clearance is vital for regulating mitochondrial function and homeostasis. These results reinforce the importance of carefully evaluating the PGC1α-boosting strategies in a context-dependent manner to facilitate clinical translation of novel cardioprotective therapies.

[Endonuclease modified comet assay for oxidative DNA damage induced by detection of genetic toxicants].

OBJECTIVE: The aim of this study was to investigate the use of the lesion-specific endonucleases-modified comet assay for analysis of DNA oxidation in cell lines. METHODS: DNA breaks and oxidative damage were evaluated by normal alkaline and formamidopyrimidine-DNA-glycosylase (FPG) modified comet assays. Cytotoxicity were assessed by MTT method. The human bronchial epithelial cell (16HBE) were treated with benzo (a) pyrene (B(a)P), methyl methanesulfonate (MMS), colchicine (COL) and vincristine (VCR) respectively, and the dose is 20 µmol/L, 25 mg/ml, 5 mg/L and 0.5 mg/L for 24 h, respectively. Oxidative damage was also detected by levels of reactive oxygen species in treated cells. RESULTS: Four genotoxicants give higher cytotoxicity and no significant changes on parameters of comet assay treated by enzyme buffer. Cell survival rate were (59.69 ± 2.60) %, (54.33 ± 2.81) %, (53.11 ± 4.00) %, (51.43 ± 3.92) % in four groups, respectively. There was the direct DNA damage induced by test genotoxicants presented by tail length, Olive tail moment (TM) and tail DNA (%) in the comet assay. The presence of FPG in the assays increased DNA migration in treated groups when compared to those without it, and the difference was statistically significant which indicated that the clastogen and aneugen could induce oxidative damage in DNA strand. In the three parameters, the Olive TM was changed most obviously after genotoxicants treatment. In the contrast group, the Olive TM of B(a) P,MMS, COL,VCR in the contrast groups were 22.99 ± 17.33, 31.65 ± 18.86, 19.86 ± 9.56 and 17.02 ± 9.39, respectively, after dealing with the FPG, the Olive TM were 34.50 ± 17.29, 43.80 ± 10.06, 33.10 ± 12.38, 28.60 ± 10.53, increased by 58.94%, 38.48%, 66.86% and 68.21%, respectively (t value was 3.91, 3.89, 6.66 and 3.87, respectively, and all P < 0.05), and the correlation between Olive TM and reactive oxygen species was better than other parameters (r = 0.77, P < 0.05). CONCLUSION: This study indicates that FPG-comet assay appears more specific for detecting oxidative DNA damage induced by genotoxicants exposure, and the application of comet assay will be expanded. The endonuclease modified comet assay will be used widely in the toxicology and molecular epidemiology study.

[Relationship between pesticide exposure and adverse pregnancy outcomes among famers: a meta-analysis].

OBJECTIVE: To analyze the relationship between pesticide exposure and adverse pregnancy outcomes in famers. METHODS: A search was conducted to collect the articles about the relationship between pesticide exposure and adverse pregnancy outcomes published worldwide from 1990 to February 2012. Meta-analysis was performed on the collected articles using RevMan 4.2 software. RESULTS: Twelve articles were collected. Compared with the controls, the pesticide-exposed famers showed a combined odds ratio (OR) for spontaneous abortion of 1.52 (95%CI: 1.04 ∼ 2.21; P = 0.03), a combined OR for premature birth of 1.33 (95%CI: 1.09 ∼ 1.61; P = 0.005), a combined OR for dead fetus of 1.22 (95%CI: 1.16 ∼ 1.29; P < 0.01), a combined OR for stillbirth of 1.90 (95%CI: 0.58 ∼ 6.28; P = 0.29), a combined OR for birth defect of 2.02 (95%CI: 0.84 - 4.69; P = 0.12), a combined OR for low birth weight of 1.62 (95%CI: 0.60 ∼ 4.39; P = 0.34), a combined OR for neonatal death of 2.18 (95%CI: 0.54 ∼ 8.88; P = 0.28), and a combined OR for delayed conception of 1.43 (95%CI: 0.93 ∼ 2.18; P = 0.1). Pesticide exposure increased the risks for spontaneous abortion, premature birth, and dead fetus, but was not significantly associated with stillbirth, birth defect, low birth weight, neonatal death, and delayed conception. CONCLUSION: Pesticide exposure can cause adverse pregnancy outcomes in farmers, increasing the risks of spontaneous abortion, premature birth, and dead fetus.