Probing the Global Cellular Responses to Lipotoxicity Caused by Saturated Fatty Acids.

Excessive levels of saturated fatty acids are toxic to cells, although the basis for this lipotoxicity remains incompletely understood. Here, we analyzed the transcriptome, lipidome, and genetic interactions of human leukemia cells exposed to palmitate. Palmitate treatment increased saturated glycerolipids, accompanied by a transcriptional stress response, including upregulation of the endoplasmic reticulum (ER) stress response. A comprehensive genome-wide short hairpin RNA (shRNA) screen identified >350 genes modulating lipotoxicity. Among previously unknown genetic modifiers of lipotoxicity, depletion of RNF213, a putative ubiquitin ligase mutated in Moyamoya vascular disease, protected cells from lipotoxicity. On a broader level, integration of our comprehensive datasets revealed that changes in di-saturated glycerolipids, but not other lipid classes, are central to lipotoxicity in this model. Consistent with this, inhibition of ER-localized glycerol-3-phosphate acyltransferase activity protected from all aspects of lipotoxicity. Identification of genes modulating the response to saturated fatty acids may reveal novel therapeutic strategies for treating metabolic diseases linked to lipotoxicity.

Metabolic transitions regulate global protein fatty acylation.

Intermediary metabolites and flux through various pathways have emerged as key determinants of post-translational modifications. Independently, dynamic fluctuations in their concentrations are known to drive cellular energetics in a bi-directional manner. Notably, intracellular fatty acid pools that drastically change during fed and fasted states act as precursors for both ATP production and fatty acylation of proteins. Protein fatty acylation is well regarded for its role in regulating structure and functions of diverse proteins; however, the effect of intracellular concentrations of fatty acids on protein modification is less understood. In this regard, we unequivocally demonstrate that metabolic contexts, viz. fed and fasted states, dictate the extent of global fatty acylation. Moreover, we show that presence or absence of glucose that influences cellular and mitochondrial uptake/utilization of fatty acids and affects palmitoylation and oleoylation, which is consistent with their intracellular abundance in fed and fasted states. Employing complementary approaches including click-chemistry, lipidomics, and imaging, we show the top-down control of cellular metabolic state. Importantly, our results establish the crucial role of mitochondria and retrograde signaling components like SIRT4, AMPK, and mTOR in orchestrating protein fatty acylation at a whole cell level. Specifically, pharmacogenetic perturbations that alter either mitochondrial functions and/or retrograde signaling affect protein fatty acylation. Besides illustrating the cross-talk between carbohydrate and lipid metabolism in mediating bulk post-translational modification, our findings also highlight the involvement of mitochondrial energetics.

Palmitate-induced insulin resistance causes actin filament stiffness and GLUT4 mis-sorting without altered Akt signalling.

Skeletal muscle insulin resistance, a major contributor to type 2 diabetes, is linked to the consumption of saturated fats. This insulin resistance arises from failure of insulin-induced translocation of glucose transporter type 4 (GLUT4; also known as SLC2A4) to the plasma membrane to facilitate glucose uptake into muscle. The mechanisms of defective GLUT4 translocation are poorly understood, limiting development of insulin-sensitizing therapies targeting muscle glucose uptake. Although many studies have identified early insulin signalling defects and suggest that they are responsible for insulin resistance, their cause-effect has been debated. Here, we find that the saturated fat palmitate (PA) causes insulin resistance owing to failure of GLUT4 translocation in skeletal muscle myoblasts and myotubes without impairing signalling to Akt2 or AS160 (also known as TBC1D4). Instead, PA altered two basal-state events: (1) the intracellular localization of GLUT4 and its sorting towards a perinuclear storage compartment, and (2) actin filament stiffness, which prevents Rac1-dependent actin remodelling. These defects were triggered by distinct mechanisms, respectively protein palmitoylation and endoplasmic reticulum (ER) stress. Our findings highlight that saturated fats elicit muscle cell-autonomous dysregulation of the basal-state machinery required for GLUT4 translocation, which 'primes' cells for insulin resistance.

Butyrylcholinesterase in lipid metabolism: A new outlook.

Cholinesterase enzymes acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are traditionally associated with the termination of acetylcholine mediated neural signaling. The fact that these ubiquitous enzymes are also found in tissues not involved in neurotransmission has led to search for alternative functions for these enzymes. Cholinesterases are reported to be involved in many lipid related disease states. Taking into view that lipases and cholinesterases belong to the same enzyme class and by comparing the catalytic sites, we propose a new outlook on the link between BChE and lipid metabolism. The lipogenic substrates of BChE that have recently emerged in contrast to traditional cholinesterase substrates are explained through the hydrolytic capacity of BChE for ghrelin, 4-methyumbelliferyl (4-mu) palmitate, and arachidonoylcholine and through endogenous lipid mediators such as cannabinoids like anandamide and essential fatty acids. The abundance of BChE in brain, intestine, liver, and plasma, tissues with active lipid metabolism, supports the idea that BChE may be involved in lipid hydrolysis. BChE is also regulated by various lipids such as linoleic acid, alpha-linolenic acid or dioctanoylglycerol, whereas AChE is inhibited. The finding that BChE is able to hydrolyze 4-mu palmitate at a pH where lipases are less efficient points to its role as a backup in lipolysis. In diseases such as Alzheimer, in which elevated BChE and impaired lipid levels are observed, the lipolytic activity of BChE might be involved. It is possible to suggest that fatty acids such as 4-mu palmitate, ghrelin, arachidonoylcholine, essential fatty acids, and other related lipid mediators regulate cholinesterases, which could lead to some sort of compensatory mechanism at high lipid concentrations.

Relapse Rates With Paliperidone Palmitate in Adult Patients With Schizophrenia: Results for the 6-Month Formulation From an Open-label Extension Study Compared to Real-World Data for the 1-Month and 3-Month Formulations.

BACKGROUND: The 3 paliperidone palmitate (PP) long-acting injectable antipsychotic formulations, PP 1-month (PP1M), PP 3-month (PP3M), and PP 6-month (PP6M), have shown to reduce the risk of relapse in schizophrenia. The current phase-4 study constructed external comparator arms (ECAs) using real-world data for PP3M and PP1M and compared relapse prevention rates with PP6M from an open-label extension (OLE) study in adult patients with schizophrenia. METHODS: PP6M data were derived from a single-arm, 24-month, OLE study (NCT04072575), which included patients with schizophrenia who completed a 12-month randomized, double-blind, noninferiority, phase-3 study (NCT03345342) without relapse. Patients in the PP3M and PP1M ECAs were identified from the IBM® MarketScan® Multistate Medicaid Database based on similar eligibility criteria as the PP6M cohort. RESULTS: A total of 178 patients were included in each cohort following propensity score matching. Most patients were men (>70%; mean age: 39-41 years). Time to relapse (primary analysis based on Kaplan-Meier estimates) was significantly delayed in the PP6M cohort (P < .001, log-rank test). The relapse rate was lower in the PP6M cohort (3.9%) vs PP3M (20.2%) and PP1M (29.8%) cohorts. Risk of relapse decreased significantly (P < .001) by 82% for PP6M vs PP3M (HR = 0.18 [95% CI = 0.08 to 0.40]), 89% for PP6M vs PP1M (HR = 0.11 [0.05 to 0.25]), and 35% for PP3M vs PP1M (HR = 0.65 [0.42 to 0.99]; P = .043). Sensitivity analysis confirmed findings from the primary analysis. Although the ECAs were matched to mimic the characteristics of the PP6M cohort, heterogeneity between the groups could exist due to factors including prior study participation, unmeasured confounders, variations in data capture and quality, and completeness of clinical information. CONCLUSIONS: In a clinical trial setting, PP6M significantly delayed time to relapse and demonstrated lower relapse rates compared with PP3M and PP1M treatments in real-world settings among adult patients with schizophrenia. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04072575; EudraCT number: 2018-004532-30.

SIRT1 activation attenuates palmitate induced apoptosis in C2C12 muscle cells.

BACKGROUND: Type 2 diabetes is characterized by insulin resistance, which manifests mainly in skeletal muscles. SIRT1 has been found to play a role in the insulin signaling pathway. However, the molecular underpinnings of SIRT1's function in palmitate fatty acid-induced apoptosis still need to be better understood. METHODS: In this research, skeletal muscle cells are treated with palmitate to be insulin resistant. It is approached that SIRT1 is downregulated in C2C12 muscle cells during palmitate-induced apoptosis and that activating SIRT1 mitigates this effect. RESULTS: Based on these findings, palmitate-induced apoptosis suppressed mitochondrial biogenesis by lowering PGC-1 expression, while SIRT1 overexpression boosted. The SIRT1 inhibitor sirtinol, on the other hand, decreased mitochondrial biogenesis under the same conditions. This research also shows that ROS levels rise in the conditions necessary for apoptosis induction by palmitate, and ROS inhibitors can mitigate this effect. This work demonstrated that lowering ROS levels by boosting SIRT1 expression inhibited apoptotic induction in skeletal muscle cells. CONCLUSION: This study's findings suggested that SIRT1 can improve insulin resistance in type 2 diabetes by slowing the rate of lipo-apoptosis and boosting mitochondrial biogenesis, among other benefits.

Health economics study of paliperidone palmitate in the treatment of schizophrenia: a 12-month cohort study.

BACKGROUND: To analyze the economic benefits of paliperidone palmitate in the treatment of schizophrenia. METHODS: We collected 546 patients who met the diagnostic criteria for schizophrenia according to the 《International Statistical Classification of Diseases and Related Health Problems,10th》(ICD-10). We gathered general population data such as gender, age, marital status, and education level, then initiated treatment with paliperidone palmitate. Then Follow-up evaluations were conducted at 1, 3, 6, 9, and 12 months after the start of treatment to assess clinical efficacy, adverse reactions, and injection doses. We also collected information on the economic burden before and after 12 months of treatment, as well as the number of outpatient visits and hospitalizations in the past year to analyze economic benefits. RESULTS: The baseline patients totaled 546, with 239 still receiving treatment with paliperidone palmitate 12 months later. After 12 months of treatment, the number of outpatient visits per year increased compared to before (4 (2,10) vs. 12 (4,12), Z=-5.949, P < 0.001), while the number of hospitalizations decreased (1 (1,3) vs. 1 (1,2), Z = 5.625, P < 0.001). The inpatient costs in the direct medical expenses of patients after 12 months of treatment decreased compared to before (5000(2000,12000) vs. 3000 (1000,8050), P < 0.05), while there was no significant change in outpatient expenses and direct non-medical expenses (transportation, accommodation, meal, and family accompanying expenses, etc.) (P > 0.05); the indirect costs of patients after 12 months of treatment (lost productivity costs for patients and families, economic costs due to destructive behavior, costs of seeking non-medical assistance) decreased compared to before (300(150,600) vs. 150(100,200), P < 0.05). CONCLUSION: Palmatine palmitate reduces the number of hospitalizations for patients, as well as their direct and indirect economic burdens, and has good economic benefits.

Characteristics of patients with schizophrenia switching from oral antipsychotics to once-monthly paliperidone palmitate (PP1M): a systematic review.

BACKGROUND: The utilization of once-monthly paliperidone palmitate (PP1M) in schizophrenia treatment has increased due to its enhanced adherence and convenience. However, there is limited evidence on patient characteristics that may influence treatment outcomes when switching from oral antipsychotics (OAPs) to PP1M therapy. This systematic review aims to identify such patient characteristics and explore potential beneficial factors to aid healthcare professionals in clinical practice. METHODS: A systematic literature search was conducted in the PubMed, Embase, and Cochrane Library databases up to July 19, 2022. Studies related to patients with schizophrenia who had been previously treated with OAPs and switched to PP1M were identified and included. Outcomes included the Positive and Negative Syndrome Scale (PANSS) total score, the clinical Global Impressions - Severity (CGI-S) score, the Personal and Social Performance (PSP) total score, and hospitalisation rate. Data were independently extracted and analysed. The results were presented through a narrative synthesis. RESULTS: Eleven studies with a total of 4150 patients were included, identifying nine potential characteristics. The most commonly reported characteristics was patient's prior treatment with OAPs, followed by the stage of disease, duration of illness (DI), ethnicity, reason for switching to PP1M, history of hospitalisation, time of start injection of PP1M, the PANSS and PSP total score at baseline. Patients in the acute stage, with a shorter DI, a less than 1-week time interval to PP1M injection, and a lower PANSS total score at baseline may have a trend on providing better improvements on PANSS total score. Acute stage and shorter DI also showed potential trends in reducing CGI-S score. Early initiation of PP1M, switching for reasons other than lack of efficacy, and a higher PSP score at baseline exhibited potential trends towards better PSP total score improvements. CONCLUSION: Our findings may suggest that patients in acute stage, with a shorter duration of illness, with early initiation of PP1M injection, and lower PANSS or PSP scores may trend towards better clinical results when transitioning to PP1M from OAPs. Further research is necessary to validate these potential associations and identify any unexplored characteristics. Such investigations are crucial for providing comprehensive clinical recommendations and informing treatment strategies in this context.

MG-132 activates sodium palmitate-induced autophagy in human vascular smooth muscle cells and inhibits senescence via the PI3K/AKT/mTOR axis.

OBJECTIVE: This study aimed to reveal the role and mechanism of MG-132 in delaying hyperlipidemia-induced senescence of vascular smooth muscle cells (VSMCs). METHODS: Immunohistochemistry and hematoxylin-eosin staining confirmed the therapeutic effect of MG-132 on arterial senescence in vivo and its possible mechanism. Subsequently, VSMCs were treated with sodium palmitate (PA), an activator (Recilisib) or an inhibitor (Pictilisib) to activate or inhibit PI3K, and CCK-8 and EdU staining, wound healing assays, Transwell cell migration assays, autophagy staining assays, reactive oxygen species assays, senescence-associated ß-galactosidase staining, and Western blotting were performed to determine the molecular mechanism by which MG-132 inhibits VSMC senescence. Validation of the interaction between MG-132 and PI3K using molecular docking. RESULTS: Increased expression of p-PI3K, a key protein of the autophagy regulatory system, and decreased expression of the autophagy-associated proteins Beclin 1 and ULK1 were observed in the aortas of C57BL/6J mice fed a high-fat diet (HFD), and autophagy was inhibited in aortic smooth muscle. MG-132 inhibits atherosclerosis by activating autophagy in VSMCs to counteract PA-induced cell proliferation, migration, oxidative stress, and senescence, thereby inhibiting VSMC senescence in the aorta. This process is achieved through the PI3K/AKT/mTOR signaling pathway. CONCLUSION: MG-132 activates autophagy by inhibiting the PI3K/AKT/mTOR pathway, thereby inhibiting palmitate-induced proliferation, migration, and oxidative stress in vascular smooth muscle cells and suppressing their senescence.

Safety Assessment of Zinc Salts as Used in Cosmetics.

The Expert Panel for Cosmetic Ingredient Safety (Panel) assessed the safety of 27 inorganic and organometallic zinc salts as used in cosmetic formulations; these salts are specifically of the 2+ (II) oxidation state cation of zinc. These ingredients included in this report have various reported functions in cosmetics, including hair conditioning agents, skin conditioning agents, cosmetic astringents, cosmetic biocides, preservatives, oral care agents, buffering agents, bulking agents, chelating agents, and viscosity increasing agents. The Panel reviewed the relevant data for these ingredients, and concluded that these 27 ingredients are safe in cosmetics in the present practices of use and concentration described in this safety assessment when formulated to be non-irritating.

The Impact of Phospholipid-Based Liquid Crystals' Microstructure on Stability and Release Profile of Ascorbyl Palmitate and Skin Performance.

The drug delivery potential of liquid crystals (LCs) for ascorbyl palmitate (AP) was assessed, with the emphasis on the AP stability and release profile linked to microstructural rearrangement taking place along the dilution line being investigated by a set of complementary techniques. With high AP degradation observed after 56 days, two stabilization approaches, i.e., the addition of vitamin C or increasing AP concentration, were proposed. As a rule, LC samples with the lowest water content resulted in better AP stability (up to 52% of nondegraded AP in LC1 after 28 days) and faster API release (~18% in 8 h) as compared to the most diluted sample (29% of nondegraded AP in LC8 after 28 days, and up to 12% of AP released in 8 h). In addition, LCs exhibited a skin barrier-strengthening effect with up to 1.2-fold lower transepidermal water loss (TEWL) and 1.9-fold higher skin hydration observed in vitro on the porcine skin model. Although the latter cannot be linked to LCs' composition or specific microstructure, the obtained insight into LCs' microstructure contributed greatly to our understanding of AP positioning inside the system and its release profile, also influencing the overall LCs' performance after dermal application.

In Silico Investigations on the Synergistic Binding Mechanism of Functional Compounds with Beta-Lactoglobulin.

Piceatannol (PIC) and epigallocatechin gallate (EGCG) are polyphenolic compounds with applications in the treatment of various diseases such as cancer, but their stability is poor. ß-lactoglobulin (ß-LG) is a natural carrier that provides a protective effect to small molecule compounds and thus improves their stability. To elucidate the mechanism of action of EGCG, PIC, and palmitate (PLM) in binding to ß-LG individually and jointly, this study applied molecular docking and molecular dynamics simulations combined with in-depth analyses including noncovalent interaction (NCI) and binding free energy to investigate the binding characteristics between ß-LG and compounds of PIC, EGCG, and PLM. Simulations on the binary complexes of ß-LG + PIC, ß-LG + EGCG, and ß-LG + PLM and ternary complexes of (ß-LG + PLM) + PIC, (ß-LG + PLM) + EGCG, ß-LG + PIC) + EGCG, and (ß-LG + EGCG) + PIC were performed for comparison and characterizing the interactions between binding compounds. The results demonstrated that the co-bound PIC and EGCG showed non-beneficial effects on each other. However, the centrally located PLM was revealed to be able to adjust the binding conformation of PIC, which led to the increase in binding affinity with ß-LG, thus showing a synergistic effect on the co-bound PIC. The current study of ß-LG co-encapsulated PLM and PIC provides a theoretical basis and research suggestions for improving the stability of polyphenols.

The protective effect of vitamin A palmitate eye gel on the ocular surface during general anaesthesia surgery: a randomized controlled trial.

PURPOSE: To investigate the change in tear production associated with general anesthesia and the protective effect of vitamin A palmitate eye gel on the ocular surface during general anesthesia. METHODS: This double-blind, randomized clinical trial included patients undergoing non-ophthalmic surgery under general anesthesia who randomly received vitamin A palmitate eye gel and taping for one eye (Group A, n = 60) or taping alone for the other eye (Group B, n = 60). Symptom assessment in dry eye (SANDE) score, tear film break-up time (TBUT), corneal fluorescein staining (CFS) score, and Schirmer tear test I (STT-1) were analyzed under a hand-held slit lamp before anesthesia (T0), 0.5 h postoperatively (T1), and 24 h postoperatively (T2). RESULTS: At 0.5 h postoperatively, an increase in CFS score was observed in both groups (P < 0.05 in Group A and P < 0.01 in Group B), and the participants in Group A had less corneal abrasions than those in Group B. STT-1 significantly increased in Group A (P < 0.05), while it significantly decreased in Group B (P < 0.001). The changes between the two groups were statistically significant (P < 0.001). At 24 h postoperatively, both CFS score and STT-1 almost returned to baseline levels in the two groups. In both groups, the SANDE score and TBUT showed little change at 0.5 h and 24 h postoperatively (all P > 0.05). CONCLUSION: Vitamin A palmitate eye gel effectively protected the ocular surface and aqueous supplementation during general anesthesia. TRIAL REGISTRATION: This study was registered in the Chinese Clinical Trial Registry (ChiCTR2100052140) on 20/10/2021.

Nicotinamide N-methyltransferase upregulation contributes to palmitate-elicited peroxisome proliferator-activated receptor transactivation in hepatocytes.

Peroxisome proliferator-activated receptor γ (PPARγ) plays a pivotal role in regulating lipid metabolism and hepatic PPARγ transactivation contributes to fatty liver development. Fatty acids (FAs) are well-known endogenous ligands for PPARγ. Palmitate, a 16-C saturated FA (SFA) and the most abundant SFA in human circulation, is a strong inducer of hepatic lipotoxicity, a central pathogenic factor for various fatty liver diseases. In this study, using both alpha mouse liver 12 (AML12) and primary mouse hepatocytes, we investigated the effects of palmitate on hepatic PPARγ transactivation and underlying mechanisms, as well as the role of PPARγ transactivation in palmitate-induced hepatic lipotoxicity, all of which remain ambiguous currently. Our data revealed that palmitate exposure was concomitant with both PPARγ transactivation and upregulation of nicotinamide N-methyltransferase (NNMT), a methyltransferase catalyzing the degradation of nicotinamide, the predominant precursor for cellular NAD+ biosynthesis. Importantly, we discovered that PPARγ transactivation by palmitate was blunted by NNMT inhibition, suggesting that NNMT upregulation plays a mechanistic role in PPARγ transactivation. Further investigations uncovered that palmitate exposure is associated with intracellular NAD+ decline and NAD+ replenishment with NAD+-enhancing agents, nicotinamide and nicotinamide riboside, obstructed palmitate-induced PPARγ transactivation, implying that cellular NAD+ decline resulted from NNMT upregulation represents a potential mechanism behind palmitate-elicited PPARγ transactivation. At last, our data showed that the PPARγ transactivation marginally ameliorated palmitate-induced intracellular triacylglycerol accumulation and cell death. Collectively, our data provided the first-line evidence supporting that NNMT upregulation plays a mechanistic role in palmitate-elicited PPARγ transactivation, potentially through reducing cellular NAD+ contents.NEW & NOTEWORTHY Hepatic PPARγ transactivation contributes to fatty liver development. Saturated fatty acids (SFAs) induce hepatic lipotoxicity. Here, we investigated whether and how palmitate, the most abundant SFA in the human blood, affects PPARγ transactivation in hepatocytes. We reported for the first time that upregulation of nicotinamide N-methyltransferase (NNMT), a methyltransferase catalyzing the degradation of nicotinamide, the predominant precursor for cellular NAD+ biosynthesis, plays a mechanistic role in regulating palmitate-elicited PPARγ transactivation through reducing intracellular NAD+ contents.

ATF4-mediated CD36 upregulation contributes to palmitate-induced lipotoxicity in hepatocytes.

Hepatic lipotoxicity plays a central role in the pathogenesis of nonalcoholic fatty liver disease; however, the underlying mechanisms remain elusive. Here, using both cultured hepatocytes (AML-12 cells and primary mouse hepatocytes) and the liver-specific gene knockout mice, we investigated the mechanisms underlying palmitate-elicited upregulation of CD36, a class B scavenger receptor mediating long-chain fatty acids uptake, and its role in palmitate-induced hepatolipotoxicity. We found that palmitate upregulates hepatic CD36 expression. Despite being a well-established target gene of PPARγ transactivation, our data demonstrated that the palmitate-induced CD36 upregulation in hepatocytes is in fact PPARγ-independent. We previously reported that the activation of ATF4, one of three canonical pathways activated upon endoplasmic reticulum (ER) stress induction, contributes to palmitate-triggered lipotoxicity in hepatocytes. In this study, our data revealed for the first time that ATF4 plays a critical role in mediating hepatic CD36 expression. Genetic inhibition of ATF4 attenuated CD36 upregulation induced by either palmitate or ER stress inducer tunicamycin in hepatocytes. In mice, tunicamycin upregulates liver CD36 expression, whereas hepatocyte-specific ATF4 knockout mice manifest lower hepatic CD36 expression when compared with control animals. Furthermore, we demonstrated that CD36 upregulation upon palmitate exposure represents a feedforward mechanism in that siRNA knockdown of CD36 in hepatocytes blunted ATF4 activation induced by both palmitate and tunicamycin. Finally, we confirmed that the ATF4-CD36 pathway activation contributes to palmitate-induced hepatolipotoxicity as genetic inhibition of either ATF4 or CD36 alleviated cell death and intracellular triacylglycerol accumulation. Collectively, our data demonstrate that CD36 upregulation by ATF4 activation contributes to palmitate-induced hepatic lipotoxicity.NEW & NOTEWORTHY We provided the initial evidence that ATF4 is a principal transcription factor mediating hepatic CD36 expression in that both palmitate- and ER stress-elicited CD36 upregulation was blunted by ATF4 gene knockdown in hepatocytes, and hepatocyte-specific ATF4 knockout mice manifested lower hepatic CD36 expression. We further confirmed that the ATF4-CD36 pathway activation contributes to palmitate-induced hepatolipotoxicity as genetic inhibition of either ATF4 or CD36 alleviated cell death and intracellular triacylglycerol accumulation in response to exogenous palmitate exposure.

Regulation of hippocampal excitatory synapses by the Zdhhc5 palmitoyl acyltransferase.

Palmitoylation is the most common post-translational lipid modification in the brain; however, the role of palmitoylation and palmitoylating enzymes in the nervous system remains elusive. One of these enzymes, Zdhhc5, has previously been shown to regulate synapse plasticity. Here, we report that Zdhhc5 is also essential for the formation of excitatory, but not inhibitory, synapses both in vitro and in vivo. We demonstrate in vitro that this is dependent on the enzymatic activity of Zdhhc5, its localization at the plasma membrane and its C-terminal domain, which has been shown to be truncated in a patient with schizophrenia. Loss of Zdhhc5 in mice results in a decrease in the density of excitatory hippocampal synapses accompanied by alterations in membrane capacitance and synaptic currents, consistent with an overall decrease in spine number and silent synapses. These findings reveal an important role for Zdhhc5 in the formation and/or maintenance of excitatory synapses.

FUNDC1 modulates mitochondrial defects and pancreatic ß-cell dysfunction under lipotoxicity.

Insulin resistance and many metabolic disorders are causally linked to mitochondrial dysfunction or defective mitochondrial quality control. Mitophagy is a highly selective mechanism that recognizes and removes damaged mitochondria to maintain mitochondrial homeostasis. Here, we addressed the potential role of FUNDC1, a mediator of mitophagy, in pancreatic ß-cell dysfunction under lipotoxicity. In pancreatic MIN6 cells, FUNDC1 deficiency aggravated palmitate-induced mitochondrial dysfunction, which led to cell death and insulin insensitivity. Interestingly, FUNDC1 overexpression prevented these cellular harms brought on by palmitate. In mice models, pancreatic-specific FUNDC1 overexpression alleviated high-fat diet (HFD)-induced insulin resistance and obesity. Mechanistically, pancreatic-specific overexpression of FUNDC1 ameliorated mitochondrial defects and endoplasmic reticulum (ER) stress upon HFD. Our research indicates that FUNDC1 plays an essential role in apoptosis and dysfunction of pancreatic ß-cells via modulating lipotoxicity-induced mitochondrial defects.

FFA-Fetuin-A regulates DPP-IV expression in pancreatic beta cells through TLR4-NFkB pathway.

Dipeptidyl peptidase 4 (DPP-IV) is a ubiquitous proteolytic enzyme that cleaves incretin hormones, such as glucagon-like peptide 1 (GLP1) and gastric inhibitory protein (GIP), leading to reduced glucose stimulated insulin secretion from the pancreatic beta cells. The functionally active enzyme is present in a membrane bound form in several cell types as well as in a soluble form in the circulation. The present report deals with DPP-IV expression and its regulation in the pancreatic beta cells in presence of free fatty acids (FFAs) and Fetuin-A, a circulatory glycoprotein associated with insulin resistance in humans and animals. FFA and Fetuin-A individually or in combination trigger DPP-IV expression in MIN6 cells. Islets isolated from high fat diet fed (HFD) mice (16 weeks) showed higher levels of DPP-IV expression than standard diet (SD) fed mice. Fetuin-A increased DPP-IV expression in HFD mice (4 weeks). Inhibition of TLR4 or NFkB prevented palmitate-Fetuin-A mediated DPP-IV expression in MIN6. It has been seen that Fetuin-A alone also could trigger DPP-IV expression in MIN6 cells via NFkB. Additionally, palmitate treatment exhibited reduced level of soluble DPP-IV in the media of MIN6 culture, which corroborated with the expression pattern of its protease, KLK5 that cleaves and releases the membrane bound DPP-IV into the secretion. Our results demonstrate that FFA-Fetuin-A upregulates DPP-IV expression in the pancreatic beta cells through the TLR4-NFkB pathway.

Methyl Palmitate Modulated NMDA-Induced Cerebral Hyperemia in Hypertensive Rats.

N-methyl-D-aspartate (NMDA) receptors were found to be dysfunctional in hypertensive rats. Methyl palmitate (MP) has been shown to diminish the nicotine-induced increase in blood flow in the brainstem. The aim of this study was to determine how MP modulated NMDA-induced increased regional cerebral blood flow (rCBF) in normotensive (WKY), spontaneously hypertensive (SHR), and renovascular hypertensive (RHR) rats. The increase in rCBF after the topical application of experimental drugs was measured using laser Doppler flowmetry. Topical NMDA application induced an MK-801-sensitive increase in rCBF in anesthetized WKY rats, which was inhibited by MP pretreatments. This inhibition was prevented by pretreatment with chelerythrine (a PKC inhibitor). The NMDA-induced increase in rCBF was also inhibited by the PKC activator in a concentration-dependent manner. Neither MP nor MK-801 affected the increase in rCBF induced by the topical application of acetylcholine or sodium nitroprusside. Topical application of MP to the parietal cortex of SHRs, on the other hand, increased basal rCBF slightly but significantly. MP enhanced the NMDA-induced increase in rCBF in SHRs and RHRs. These results suggested that MP had a dual effect on the modulation of rCBF. MP appears to play a significant physiological role in CBF regulation.

Long-Term Efficacy and Safety of Paliperidone 6-Month Formulation: An Open-Label 2-Year Extension of a 1-Year Double-Blind Study in Adult Participants With Schizophrenia.

BACKGROUND: Paliperidone palmitate 6-month (PP6M) demonstrated noninferiority to paliperidone palmitate 3-month in preventing relapse in patients with schizophrenia in a phase 3 double-blind (DB) study (NCT03345342). Here, we report long-term efficacy and safety results from a 2-year single-arm, open-label extension (OLE; NCT04072575) of this DB study. METHODS: Participants who completed the DB study without relapse were enrolled and followed-up every 3 months up to 2 years. Participants received 4 PP6M gluteal injections (700/1000 mg eq.) at baseline, 6-month, 12-month, and 18-month visits. Efficacy endpoints included assessment of relapse, Positive and Negative Syndrome Scale total score, Personal and Social Performance score, and Clinical Global Impression-Severity scale change from baseline. Safety was assessed by treatment-emergent adverse events (TEAEs), physical examinations, and laboratory tests. RESULTS: Of 178 participants enrolled, 154 (86.5%) completed the OLE (mean age: 40.4 years, men: 70.8%; mean duration of PP6M exposure during OLE: 682.1 days). Overall, 7/178 (3.9%) participants relapsed between 20 and 703 days after enrolment. Mean (SD) changes from baseline to endpoint were as follows: Positive and Negative Syndrome Scale total score, 0.7 (8.22); Clinical Global Impression-Severity, 0.0 (0.51); and Personal and Social Performance Scale, 0.5 (7.47). Overall, 111/178 participants (62.4%) reported ≥1 TEAE; most common (>5%) TEAEs were headache (13.5%) and increased blood prolactin/hyperprolactinemia (18.0%); 8/178 (4.5%) participants experienced serious TEAEs, and 6/178 (3.4%) participants withdrew due to TEAEs. No deaths were reported. CONCLUSIONS: The relapse rate observed with PP6M during the 2-year OLE was low (3.9%). Clinical and functional improvements demonstrated in the DB study were maintained during OLE, and no new safety concerns were identified. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04072575; EudraCT number: 2018-004532-30.