ABCA7 deficiency causes neuronal dysregulation by altering mitochondrial lipid metabolism.

ABCA7 loss-of-function variants are associated with increased risk of Alzheimer's disease (AD). Using ABCA7 knockout human iPSC models generated with CRISPR/Cas9, we investigated the impacts of ABCA7 deficiency on neuronal metabolism and function. Lipidomics revealed that mitochondria-related phospholipids, such as phosphatidylglycerol and cardiolipin were reduced in the ABCA7-deficient iPSC-derived cortical organoids. Consistently, ABCA7 deficiency-induced alterations of mitochondrial morphology accompanied by reduced ATP synthase activity and exacerbated oxidative damage in the organoids. Furthermore, ABCA7-deficient iPSC-derived neurons showed compromised mitochondrial respiration and excess ROS generation, as well as enlarged mitochondrial morphology compared to the isogenic controls. ABCA7 deficiency also decreased spontaneous synaptic firing and network formation in iPSC-derived neurons, in which the effects were rescued by supplementation with phosphatidylglycerol or NAD+ precursor, nicotinamide mononucleotide. Importantly, effects of ABCA7 deficiency on mitochondria morphology and synapses were recapitulated in synaptosomes isolated from the brain of neuron-specific Abca7 knockout mice. Together, our results provide evidence that ABCA7 loss-of-function contributes to AD risk by modulating mitochondria lipid metabolism.

HMGA1 chromatin regulators induce transcriptional networks involved in GATA2 and proliferation during MPN progression.

Myeloproliferative neoplasms (MPNs) transform to myelofibrosis (MF) and highly lethal acute myeloid leukemia (AML), although the actionable mechanisms driving progression remain elusive. Here, we elucidate the role of the high mobility group A1 (HMGA1) chromatin regulator as a novel driver of MPN progression. HMGA1 is upregulated in MPN, with highest levels after transformation to MF or AML. To define HMGA1 function, we disrupted gene expression via CRISPR/Cas9, short hairpin RNA, or genetic deletion in MPN models. HMGA1 depletion in JAK2V617F AML cell lines disrupts proliferation, clonogenicity, and leukemic engraftment. Surprisingly, loss of just a single Hmga1 allele prevents progression to MF in JAK2V617F mice, decreasing erythrocytosis, thrombocytosis, megakaryocyte hyperplasia, and expansion of stem and progenitors, while preventing splenomegaly and fibrosis within the spleen and BM. RNA-sequencing and chromatin immunoprecipitation sequencing revealed HMGA1 transcriptional networks and chromatin occupancy at genes that govern proliferation (E2F, G2M, mitotic spindle) and cell fate, including the GATA2 master regulatory gene. Silencing GATA2 recapitulates most phenotypes observed with HMGA1 depletion, whereas GATA2 re-expression partially rescues leukemogenesis. HMGA1 transactivates GATA2 through sequences near the developmental enhancer (+9.5), increasing chromatin accessibility and recruiting active histone marks. Further, HMGA1 transcriptional networks, including proliferation pathways and GATA2, are activated in human MF and MPN leukemic transformation. Importantly, HMGA1 depletion enhances responses to the JAK2 inhibitor, ruxolitinib, preventing MF and prolonging survival in murine models of JAK2V617F AML. These findings illuminate HMGA1 as a key epigenetic switch involved in MPN transformation and a promising therapeutic target to treat or prevent disease progression.

WGCNA and transcriptome profiling reveal hub genes for key development stage seed size/oil content between wild and cultivated soybean.

BACKGROUND: Soybean is one of the most important oil crops in the world. The domestication of wild soybean has resulted in significant changes in the seed oil content and seed size of cultivated soybeans. To better understand the molecular mechanisms of seed formation and oil content accumulation, WDD01514 (E1), ZYD00463 (E2), and two extreme progenies (E23 and E171) derived from RILs were used for weighted gene coexpression network analysis (WGCNA) combined with transcriptome analysis. RESULTS: In this study, both seed weight and oil content in E1 and E171 were significantly higher than those in E2 and E23, and 20 DAF and 30 DAF may be key stages of soybean seed oil content accumulation and weight increase. Pathways such as "Photosynthesis", "Carbon metabolism", and "Fatty acid metabolism", were involved in oil content accumulation and grain formation between wild and cultivated soybeans at 20 and 30 DAF according to RNA-seq analysis. A total of 121 oil content accumulation and 189 seed formation candidate genes were screened from differentially expressed genes. WGCNA identified six modules related to seed oil content and seed weight, and 76 candidate genes were screened from modules and network. Among them, 16 genes were used for qRT-PCR and tissue specific expression pattern analysis, and their expression-levels in 33-wild and 23-cultivated soybean varieties were subjected to correlation analysis; some key genes were verified as likely to be involved in oil content accumulation and grain formation. CONCLUSIONS: Overall, these results contribute to an understanding of seed lipid metabolism and seed size during seed development, and identify potential functional genes for improving soybean yield and seed oil quantity.

Effects of choline deficiency and supplementation on lipid droplet accumulation in bovine primary liver cells in vitro.

Rumen-protected choline (RPC) supplementation in the periparturient period has in some instances prevented and alleviated fatty liver disease in dairy cows. Mechanistically, however, it is unclear how choline prevents the accumulation of lipid droplets (LD) in liver cells. In this study, primary liver cells isolated from liver tissue obtained via puncture biopsy from 3 nonpregnant mid-lactation multiparous Holstein cows (∼160 d postpartum) were used. Analyses of LD via oil red O staining, protein abundance via Western blotting, and phospholipid content and composition measured by thin-layer chromatography and HPLC/mass spectrometry were performed in liver cells cultured in choline-deficient medium containing 150 µmol/L linoleic acid for 24 h. In a subsequent experiment, lipophagy was assessed in liver cells cultured with 30, 60, or 90 µmol/L choline-chloride. All data were analyzed statistically using SPSS 20.0 via t-tests or one-way ANOVA. Compared with liver cells cultured in Dulbecco's Modified Eagle Medium alone, choline deficiency increased the average diameter of LD (1.59 vs. 2.10 µm), decreased the proportion of small LD (<2 µm) from 75.3% to 56.6%, and increased the proportion of large LD (>4 µm) from 5.6% to 15.0%. In addition, the speed of LD fusion was enhanced by the absence of choline. Among phospholipid species, the phosphatidylcholine (PC) content of liver cells decreased by 34.5%. Seventeen species of PC (PC [18:2_22:6], PC [15:0_16:1], PC [14:0_20:4], and so on) and 6 species of lysophosphatidylcholine (LPC; LPC [15:0/0:0]), PC (22:2/0:0), LPC (20:2/0:0), and so on] were decreased, while PC (14:1_16:1) and LPC (0:0/20:1) were increased. Choline deficiency increased the triglyceride (TAG) content (0.57 vs. 0.39 µmol/mg) in liver cells and increased the protein abundance of sterol regulatory element binding protein 1, sterol regulatory element binding protein cleavage activation protein, and fatty acid synthase by 23.5%, 17%, and 36.1%, respectively. Upon re-supplementation with choline, the phenotype of LD (TAG content, size, proportion, and phospholipid profile) was reversed, and the ratio of autophagy marker LC3II/LC3I protein was significantly upregulated in a dose-dependent manner. Overall, at least in vitro in mid-lactation cows, these data demonstrated that PC synthesis is necessary for normal LD formation, and both rely on choline availability. According to the limitation of the source of liver cells used, further work should be conducted to ascertain that these effects are applicable to liver cells from postpartum cows, the physiological stage where the use of RPC has been implemented for the prevention and treatment of fatty liver.

Size, number and phospholipid composition of milk fat globules are affected by dietary conjugated linoleic acid.

Milk fat globules (MFGs) surround the triacylglycerol core that composes milk fat. The aim of this study is to induce milk fat depression via dietary conjugated linoleic acid (CLA) supplementation to study MFG size parameters, number and glycerophospholipid composition. Eighteen Holstein dairy cows (136 ± 28 days in milk, 571 ± 37.9 kg body weight, 27.6 ± 2.1 kg milk/day) were selected and randomly assigned to a control or CLA group for a 14-day period. Cows were fed a basal diet (control, n = 8) or the control plus 400 g/day CLA (C18:2 cis-9, trans-11 38.1% and C18:2 trans-10, cis-12 36.8%) (n = 10) for 7 days after which the CLA group was switched to the basal diet for another 7 days along with the control group. Cow performance, milk composition, MFG size and numbers were measured daily. On the seventh day after the start of the experiment, milk samples were identified and the quantification of glycerophospholipid compounds, and RNA were isolated from milk fat samples for a real-time polymerase chain reaction. Compared with control, at Day 7 from the start of feeding, supplemental CLA did not affect milk production (28.09 vs. 28.50 kg/day), dry matter intake (14.9 vs. 15.4 kg/day), or milk protein (3.55/100 vs. 3.70 g/100 ml) and lactose contents (5.11/100 vs. 5.17 g/100 ml). However, although the specific surface area of MFG (2138 vs. 1815 m²/kg) was greater, CLA reduced milk fat content (1.95/100 vs 3.64 g/100 ml on Day 7) and particle size parameters of MFG. The number of MFG gradually decreased until Day 7 of feeding, and then increased by Day 14 (2.96 × 109 on Day 1, 1.63 × 109 on Day 7 and 2.28 × 109 on Day 14) in the CLA group. Compared with control, glycerophospholipid analysis revealed that concentrations of phosphatidylcholine (PC) (e.g., PC [16:0/18:1] 20322 vs. 29793 nmol/L), lysophosphatidylethanolamine (LPE) (e.g., LPE [18:1] 956 vs. 4610 nmol/L) and phosphatidylethanolamine (PE) (e.g., PE [16:0/18:1] 7000 vs. 9769 nmol/L) in milk lipids decreased during CLA feeding. In contrast, concentrations of phosphatidylinositol (PI) (e.g., PI [18:0/18:1] 4052 vs. 1799 nmol/L) and phosphatidylserine (PS) (e.g., PS [18:1/18:2] 9500 vs. 6843 nmol/L) increased. The messenger RNA abundance of fatty acid synthase, diacylglycerol O-acyltransferase 1, glycerol-3-phosphate acyltransferase 4 and phosphate cytidylyltransferase 1, choline, alpha (PCYT1A) were downregulated in the CLA group, confirming published data demonstrating a negative effect of CLA on lipogenesis in the mammary gland. Overall, these results provided evidence for the important role of lipogenic gene expression in the regulation of MFG size, number and glycerophospholipid composition.

Milk fat globule membrane proteins are involved in controlling the size of milk fat globules during conjugated linoleic acid-induced milk fat depression.

Milk fat globule membrane (MFGM) proteins surround the triacylglycerol core comprising milk fat globules (MFG). We previously detected a decrease in the size of fat globules during conjugated linoleic acid (CLA)-induced milk fat depression (MFD), and other studies have reported that some MFGM proteins play a central role in regulating mammary cellular lipid droplet size. However, little is known about the relationship between MFD, MFG size, and MFGM proteins in bovine milk. The aim of this study was to investigate the profile of MFGM proteins during MFD induced by CLA. Sixteen mid-lactating Holstein cows (145 ± 24 d in milk) with similar body condition and parity were divided into control and CLA groups over a 10-d period. Cows were fed a basal diet (control, n = 8) or control plus 15 g/kg of dry matter (DM) CLA (n = 8) to induce MFD. Cow performance, milk composition, and MFG size were measured daily. On d 10, MFGM proteins were extracted and identified by quantitative proteomic analysis, and western blotting was used to verify a subset of the identified MFGM proteins. Compared with controls, supplemental CLA did not affect milk production, DM intake, or milk protein and lactose contents. However, CLA reduced milk fat content (3.73 g/100 mL vs. 2.47 g/100 mL) and the size parameters volume-related diameter D[4,3] (3.72 µm vs. 3.35 µm) and surface area-related diameter D[3,2] (3.13 µm vs. 2.80 µm), but increased specific surface area of MFG (1,905 m2/kg vs. 2,188 m2/kg). In total, 177 differentially expressed proteins were detected in milk from cows with CLA-induced MFD, 60 of which were upregulated and 117 downregulated. Correlation analysis showed that MFG size was negatively correlated with various proteins, including XDH and FABP3, and positively correlated with MFG-E8, RAB19, and APOA1. The results provide evidence for an important role of MFGM proteins in regulating MFG diameter, and they facilitate a mechanistic understanding of diet-induced MFD.

Apolipoprotein E regulates lipid metabolism and α-synuclein pathology in human iPSC-derived cerebral organoids.

APOE4 is a strong genetic risk factor for Alzheimer's disease and Dementia with Lewy bodies; however, how its expression impacts pathogenic pathways in a human-relevant system is not clear. Here using human iPSC-derived cerebral organoid models, we find that APOE deletion increases α-synuclein (αSyn) accumulation accompanied with synaptic loss, reduction of GBA levels, lipid droplet accumulation and dysregulation of intracellular organelles. These phenotypes are partially rescued by exogenous apoE2 and apoE3, but not apoE4. Lipidomics analysis detects the increased fatty acid utilization and cholesterol ester accumulation in apoE-deficient cerebral organoids. Furthermore, APOE4 cerebral organoids have increased αSyn accumulation compared to those with APOE3. Carrying APOE4 also increases apoE association with Lewy bodies in postmortem brains from patients with Lewy body disease. Our findings reveal the predominant role of apoE in lipid metabolism and αSyn pathology in iPSC-derived cerebral organoids, providing mechanistic insights into how APOE4 drives the risk for synucleinopathies.

Smoothened signaling in the mouse osteoblastoid lineage is required for efficient B lymphopoiesis.

The stromal signals that promote B lymphopoiesis remain poorly understood. Hedgehog (Hh) signaling promotes B lymphopoiesis in a non-cell-autonomous fashion in vitro, and depletion of the Hh effector Smoothened (Smo) from stromal cells is associated with the loss of osteoblastoid markers. These observations suggested that Hh signaling in the osteoblastoid lineage promotes B lymphopoiesis in vivo. To test this, we employed a mouse model for conditional ablation of Smo in the osteoblastoid lineage. Depletion of Smo from osteoblastoid cells is associated with profound and selective reductions in the number and proportion of bone marrow B-lymphoid progenitors. Upon partial bone marrow ablation, mutant animals exhibit delayed repopulation of the B-lymphoid compartment after the early lymphoid progenitor stage. Primary osteoblasts from mutant mice are defective in supporting B lymphopoiesis in vitro, whereas hematopoietic progenitors from mutant mice exhibit normal differentiation. We conclude that efficient B lymphopoiesis in vivo is dependent on the maintenance of Hh signaling in the osteoblastoid lineage.

Role of Wnt Co-Receptor LRP6 in Triple Negative Breast Cancer Cell Migration and Invasion.

The low-density lipoprotein receptor-related protein 6 (LRP6) is an essential Wnt co-receptor of the Wnt/ß-catenin signaling pathway. Although studies have shown an increased expression of LRP6 in several types of cancer, its function in tumor development and progression remains to be elucidated. We herein demonstrated that LRP6 expression is up-regulated in human triple negative breast cancer (TNBC) patients and human TNBC cell lines, and that knockdown of LRP6 expression and treatment of recombinant Mesd protein (a specific inhibitor of LRP6) significantly decreased cell migration and invasion of TNBC MDA-MB-231 and BT549 cells. Interestingly, the effects of LRP6 knockdown and Mesd treatment on TNBC cell migration and invasion were more prominent than on TNBC cell proliferation/viability. Mechanistically, LRP6 knockdown and Mesd treatment inhibited Wnt/ß-catenin signaling and decreased the expression of S100A4, a mediator of cancer metastasis and a specific target of Wnt/ß-catenin signaling, in TNBC cells. Together, our data suggest that LRP6 promotes TNBC cell migration and invasion by regulating the expression and function of S100A4 via the Wnt/ß-catenin signaling pathway. J. Cell. Biochem. 118: 2968-2976, 2017. © 2017 Wiley Periodicals, Inc.

Discovery of a novel inhibitor of kinesin-like protein KIFC1.

Historically, drugs used in the treatment of cancers also tend to cause damage to healthy cells while affecting cancer cells. Therefore, the identification of novel agents that act specifically against cancer cells remains a high priority in the search for new therapies. In contrast with normal cells, most cancer cells contain multiple centrosomes which are associated with genome instability and tumorigenesis. Cancer cells can avoid multipolar mitosis, which can cause cell death, by clustering the extra centrosomes into two spindle poles, thereby enabling bipolar division. Kinesin-like protein KIFC1 plays a critical role in centrosome clustering in cancer cells, but is not essential for normal cells. Therefore, targeting KIFC1 may provide novel insight into selective killing of cancer cells. In the present study, we identified a small-molecule KIFC1 inhibitor, SR31527, which inhibited microtubule (MT)-stimulated KIFC1 ATPase activity with an IC50 value of 6.6 µM. By using bio layer interferometry technology, we further demonstrated that SR31527 bound directly to KIFC1 with high affinity (Kd=25.4 nM). Our results from computational modelling and saturation-transfer difference (STD)-NMR experiments suggest that SR31527 bound to a novel allosteric site of KIFC1 that appears suitable for developing selective inhibitors of KIFC1. Importantly, SR31527 prevented bipolar clustering of extra centrosomes in triple negative breast cancer (TNBC) cells and significantly reduced TNBC cell colony formation and viability, but was less toxic to normal fibroblasts. Therefore, SR31527 provides a valuable tool for studying the biological function of KIFC1 and serves as a potential lead for the development of novel therapeutic agents for breast cancer treatment.

Synthesis and preliminary assessment of the anticancer and Wnt/ß-catenin inhibitory activity of small amide libraries of fenamates and profens.

As part of an ongoing program to study the anticancer activity of non-steroidal anti-inflammatory drugs (NSAIDs) through generating diversity libraries of multiple NSAID scaffolds, we synthesized a series of NSAID amide derivatives and screened these sets against three cancer cell lines (prostate, colon and breast) and Wnt/ß-catenin signaling. The evaluated amide analog libraries show significant anticancer activity/cell proliferation inhibition, and specific members of the sets show inhibition of Wnt/ß-catenin signaling.

Geminin inhibits a late step in the formation of human pre-replicative complexes.

The initial step in initiation of eukaryotic DNA replication involves the assembly of pre-replicative complexes (pre-RCs) at origins of replication during the G1 phase of the cell cycle. In metazoans initiation is inhibited by the regulatory factor Geminin. We have purified the human pre-RC proteins, studied their interactions in vitro with each other and with origin DNA, and analyzed the effects of HsGeminin on formation of DNA-protein complexes. The formation of an initial complex containing the human origin recognition complex (HsORC), HsCdt1, HsCdc6, and origin DNA is cooperative, involving all possible binary interactions among the components. Maximal association of HsMCM2-7, a component of the replicative helicase, requires HsORC, HsCdc6, HsCdt1, and ATP, and is driven by interactions of HsCdt1 and HsCdc6 with multiple HsMCM2-7 subunits. Formation of stable complexes, resistant to high salt, requires ATP hydrolysis. In the absence of HsMCM proteins, HsGeminin inhibits the association of HsCdt1 with DNA or with HsORC-HsCdc6-DNA complexes. However, HsGeminin does not inhibit recruitment of HsMCM2-7 to DNA to form complexes containing all of the pre-RC proteins. In fact, HsGeminin itself is a component of such complexes, and interacts directly with the HsMcm3 and HsMcm5 subunits of HsMCM2-7, as well as with HsCdt1. Although HsGeminin does not prevent the initial formation of DNA-protein complexes containing the pre-RC proteins, it strongly inhibits the formation of stable pre-RCs that are resistant to high salt. We suggest that bound HsGeminin prevents transition of the pre-RC to a state that is competent for initiation of DNA replication.

Salinomycin suppresses LRP6 expression and inhibits both Wnt/ß-catenin and mTORC1 signaling in breast and prostate cancer cells.

Emerging evidence indicates that activation of Wnt/ß-catenin signaling at the cell surface results in inhibition of glycogen synthase kinase 3ß (GSK3ß), leading to activation of mTORC1 signaling in cancer cells. The low density lipoprotein receptor-related protein-6 (LRP6) is an essential Wnt co-receptor for Wnt/ß-catenin signaling. Salinomycin is a novel small molecule inhibitor of LRP6. In the present study, we found that LRP6 overexpression induced mTORC1 signaling activation in cancer cells, and that salinomycin was not only a potent Wnt/ß-catenin signaling inhibitor, but also a strong mTORC1 signaling antagonist in breast and prostate cancer cells. Mechanistically, salinomycin activated GSK3ß in cancer cells. Moreover, salinomycin was able to suppress the expression of cyclin D1 and survivin, two targets of both Wnt/ß-catenin and mTORC1 signaling, in prostate and breast cancer cells, and displayed remarkable anticancer activity. Our results present novel mechanisms underlying salinomycin-mediated cancer cell death.

[Effects of hyperoncotic cardiopulmonary bypass prime on extravascular lung water and cardiopulmonary function in patients undergoing coronary artery bypass surgery].

OBJECTIVE: To investigated the effect of a hyperoncotic CPB-prime with hydroxyethyl starch (HES) 6% (130/0.4) on extravascular lung water (EVLW) and post-pump cardiac and pulmonary functions. METHODS: This study plan approved by the hospital ethics committee review. In 40 randomized patients undergoing elective coronary artery bypass graft surgery (CABG), a colloid prime (COP:42.5 mmHg, HES-group, n = 20) and a crystalloid prime (Ringer's lactate, crystalloid group, n = 20) of equal volume were compared with respect to the effects on cardiopulmonary function. Cardiac index (CI), mean arterial pressure (MAP), pulmonary capillary wedge pressure (PCWP), systemic vascular resistance index (SVRI), pulmonary artery pressure (PAP), pulmonary vascular resistance index (PVRI), alveolo-arterial oxygen difference (AaDO2), pulmonary shunt fraction (Qs/QT), extravascular lung water (EVLW), COP, fluid balance and body weight were evaluated peri-operatively. RESULTS: Pre-operative demographic and clinical data, CPB-time, crossclamp time and the number of anastomoses were comparable for both groups. During CPB, COP was reduced by 22% in the HES-group [(16.7 ± 3.9) vs (21.5 ± 2.2) mmHg, P < 0.05] while it was reduced by more than 50% of the pre-CPB value [10.7 ± 2.0 vs (22.7 ± 1.9) mmHg, P < 0.05] in the crystalloid group (P < 0.05 HES-group vs. crystalloid group). Post-CPB EVLW was unchanged in the HES-group but it was elevated by 21% in the crystalloid group (P < 0.05 HES-group vs crystalloid group), CI was higher in the HES-group [(3.3 ± 0.3) vs (2.7 ± 0.7) L/min, P < 0.05]. Fluid balance was less in the HES-group (715 ± 544 vs 1 951 ± 487, P < 0.05). Post-operative weight gain could be prevented in the HES-group but not in the crystalloid group (1.4 ± 1.1 vs -0.3 ± 1.3, P < 0.05). No significant differences were seen for MAP, PAP, PCWP, SVRI, PVRI, AaDO2 and (Qs/QT) between the two groups at any time. CONCLUSIONS: Hyperoncotic CPB-prime using HES 6% improves CI and prevents EVLW accumulation in the early post-pump period, while pulmonary function is unchanged.

Micro-and nano-plastics induce kidney damage and suppression of innate immune function in zebrafish (Danio rerio) larvae.

Aquatic environments serve as critical repositories for pollutants and have significantly accumulated micro- and nanoplastics (MNPs) due to the extensive production and application of plastic products. While the disease resistance and immunity of fish are closely linked to the condition of their aquatic habitats, the specific effects of nanoplastics (NPs) and microplastics (MPs) within these environments on fish immune functions are still not fully understood. The present study utilized zebrafish (Danio rerio) embryos and larvae as model organisms to examine the impacts of polystyrene NPs (100 nm) and MPs (5 µm) on fish immune responses. Our findings reveal that NPs and MPs tend to accumulate on the surfaces of embryos and within the intestines of larvae, triggering oxidative stress and significantly increasing susceptibility to Edwardsiella piscicida infection in zebrafish larvae. Transmission electron microscopy examined that both NPs and MPs inflicted damage to the kidney, an essential immune organ, with NPs predominantly inducing endoplasmic reticulum stress and MPs causing lipid accumulation. Transcriptomic analysis further demonstrated that both NPs and MPs significantly suppress the expression of key innate immune pathways, notably the C-type lectin receptor signaling pathway and the cytosolic DNA-sensing pathway. Within these pathways, the immune factor interleukin-1 beta (il1b) was consistently downregulated in both exposure groups. Furthermore, exposure to E. piscicida resulted in restricted upregulation of il1b mRNA and protein levels, likely contributing to diminished disease resistance in zebrafish larvae exposed to MNPs. Our findings suggest that NPs and MPs similarly impair the innate immune function of zebrafish larvae and weaken their disease resistance, highlighting the significant environmental threat posed by these pollutants.

Dose-dependent effects of polystyrene nanoplastics on growth, photosynthesis, and astaxanthin synthesis in Haematococcus pluvialis.

Microalgae play an important role in aquatic ecosystems, but the widespread presence of micro- and nano-plastics (MNPs) poses significant threats to them. Haematococcus pluvialis is well-known for its ability to produce the antioxidant astaxanthin when it experiences stress from environmental conditions. Here we examined the effects of polystyrene nanoplastics (PS-NPs) at concentrations of 0.1, 1, and 10 mg/L on H. pluvialis over an 18-day period. Our results show that PS-NPs caused a significant, dose-dependent inhibition of H. pluvialis growth and a reduction in photosynthesis. Furthermore, PS-NPs severely damaged the morphology of H. pluvialis, leading to cell shrinkage, collapse, content release, and aggregation. Additionally, PS-NPs induced a dose-dependent increase in soluble protein content and a decrease in the production of extracellular polymeric substances. These findings indicate that PS-NPs has the potential to adversely affect both the physiology and morphology of H. pluvialis. An increase in reactive oxygen species and antioxidant enzyme activities was also observed, suggesting an oxidative stress response to PS-NPs exposure. Notably, the synthesis of astaxanthin, which is crucial for H. pluvialis's survival under stress, was significantly inhibited in a dose-dependent manner under strong light conditions, along with the down-regulation of genes involved in the astaxanthin biosynthesis pathway. This suggests that PS-NPs exposure reduces H. pluvialis's ability to survive under adverse conditions. This study enhances our understanding of the toxic effects of PS-NPs on microalgae and underscores the urgent need for measures to mitigate MNP pollution to protect aquatic ecosystems.

Metformin promotes the survival of random skin flaps via the activation of Nrf2/HO-1 signaling.

The random flap is one of the commonly used techniques for tissue defect repair in surgery and orthopaedics, however the risk of ischaemic necrosis at the distal end of the flap limits its size and clinical application. Metformin (Met) is a first-line medication in the treatment of type 2 diabetes, with additional effects such as anti-tumor, anti-aging, and neuroprotective properties. In this study, we aimed to investigate the biological effects and potential mechanisms of Met in improving the survival of random skin flaps. Twenty-four male Sprague-Dawley rats and 12 male C57BL/6J mice underwent McFarlane flap surgery and divided into control (Ctrl) and Met groups (100 mg/kg). The survival rate of the flap were evaluated on day 7. Angiography, Laser doppler blood flow imaging, and H&E staining were used to assess blood flow supply and the levels of microvascular density. Then, reactive oxygen species (ROS) and malondialdehyde (MDA) levels, and the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were measured by test kits. Immunohistochemistry analysis was conducted to evaluate the expression of Vascular Endothelial Growth Factor A (VEGFA), Vascular endothelial cadherin (VE-cadherin) and CD31. Rats and mice in the Met group exhibited higher flap survival rate, microcirculatory flow, and higher expression levels of VEGFA and VE-cadherin compared with the Ctrl group. In addition, the level of oxidative stress was significantly lower in the met group. And then we demonstrated that the human umbilical vein endothelial cells (HUVECs) treated with Met can alleviate tert-butyl hydroperoxide (TBHP)-stimulated cellular dysfunction and oxidative stress injury. Mechanistically, Met markedly stimulated the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1), and promoted Nrf2 nuclear translocation. Silencing of Nrf2 partially abolished the antioxidant and therapeutic effects of Met. In summary, our data have confirmed that Met has a positive effect on flap survival and reduces necrosis. The mechanism of action involves the regulation of the Nrf2/HO-1 signaling pathway to combat oxidative stress and reduce damage.

A novel histone deacetylase inhibitor W2A-16 improves the barrier integrity in brain vascular endothelial cells.

The maturation of brain microvascular endothelial cells leads to the formation of a tightly sealed monolayer, known as the blood-brain barrier (BBB). The BBB damage is associated with the pathogenesis of age-related neurodegenerative diseases including vascular cognitive impairment and Alzheimer's disease. Growing knowledge in the field of epigenetics can enhance the understanding of molecular profile of the BBB and has great potential for the development of novel therapeutic strategies or targets to repair a disrupted BBB. Histone deacetylases (HDACs) inhibitors are epigenetic regulators that can induce acetylation of histones and induce open chromatin conformation, promoting gene expression by enhancing the binding of DNA with transcription factors. We investigated how HDAC inhibition influences the barrier integrity using immortalized human endothelial cells (HCMEC/D3) and the human induced pluripotent stem cell (iPSC)-derived brain vascular endothelial cells. The endothelial cells were treated with or without a novel compound named W2A-16. W2A-16 not only activates Wnt/ß-catenin signaling but also functions as a class I HDAC inhibitor. We demonstrated that the administration with W2A-16 sustained barrier properties of the monolayer of endothelial cells, as evidenced by increased trans-endothelial electrical resistance (TEER). The BBB-related genes and protein expression were also increased compared with non-treated controls. Analysis of transcript profiles through RNA-sequencing in hCMEC/D3 cells indicated that W2A-16 potentially enhances BBB integrity by influencing genes associated with the regulation of the extracellular microenvironment. These findings collectively propose that the HDAC inhibition by W2A-16 plays a facilitating role in the formation of the BBB. Pharmacological approaches to inhibit HDAC may be a potential therapeutic strategy to boost and/or restore BBB integrity.

Modeling Lewy body disease with SNCA triplication iPSC-derived cortical organoids and identifying therapeutic drugs.

Aggregated α-synuclein (α-SYN) proteins, encoded by the SNCA gene, are hallmarks of Lewy body disease (LBD), affecting multiple brain regions. However, the specific mechanisms underlying α-SYN pathology in cortical neurons, crucial for LBD-associated dementia, remain unclear. Here, we recapitulated α-SYN pathologies in human induced pluripotent stem cells (iPSCs)-derived cortical organoids generated from patients with LBD with SNCA gene triplication. Single-cell RNA sequencing, combined with functional and molecular validation, identified synaptic and mitochondrial dysfunction in excitatory neurons exhibiting high expression of the SNCA gene, aligning with observations in the cortex of autopsy-confirmed LBD human brains. Furthermore, we screened 1280 Food and Drug Administration-approved drugs and identified four candidates (entacapone, tolcapone, phenazopyridine hydrochloride, and zalcitabine) that inhibited α-SYN seeding activity in real-time quaking-induced conversion assays with human brains, reduced α-SYN aggregation, and alleviated mitochondrial dysfunction in SNCA triplication organoids and excitatory neurons. Our findings establish human cortical LBD models and suggest potential therapeutic drugs targeting α-SYN aggregation for LBD.