👤 Geraldine Vargas

The cell-intrinsic capacity of neurons to regenerate axons requires widespread coordination of the transcriptome, activation of multiple kinases, and reorganization of the cytoskeleton. Axonal repair is also influenced by extrinsic activating factors, such as neurotrophins. Here, we found that the neurotrophin BDNF amplifies multiple neuron-intrinsic programs to foster axonal regeneration in human iPSC-derived lower motor neurons (i Show less

Type 2 diabetes has been linked to oxidative stress, inflammation, and an imbalance in the gut microbiota, all of which contribute to neuroinflammation and cognitive decline. Gut microbiota influence inflammation and produce various substances, including butyrate, a short-chain fatty acid that promotes brain-derived neurotrophic factor (BDNF), which is essential for memory. This study investigated whether prebiotics, probiotics, or a combination of both (symbiotics) could improve memory in diabetic rats. Male Wistar rats were divided into five groups: control; diabetic and obese (induced by a high-fat diet and streptozotocin); diabetic and obese with prebiotics (inulin); diabetic and obese with probiotics (Lactobacillus acidophilus); and diabetic and obese with symbiotics (inulin + L. acidophilus). Treatments lasted 42 d. Memory performance was evaluated using the Morris water maze (spatial memory) and the Eight-arm radial maze (working memory). After testing, hippocampal tissue was analyzed for inflammatory markers (TNF-α, IL-10), BDNF, and butyric acid. Diabetes impaired memory and increased neuroinflammatory markers. All supplemented groups showed improved memory. The symbiotic group exhibited the most pronounced benefits, with higher levels of BDNF, IL-10, and butyric acid, and reduced TNF-α. Electrophysiological recordings revealed that diabetes reduced the firing frequency of CA1 pyramidal cells and decreased the synaptic strength in the hippocampus. Symbiotic supplementation preserved these neuronal and synaptic functions. Symbiotic treatment effectively countered diabetes-induced cognitive deficits by reducing neuroinflammation, increasing neurotrophic support, and maintaining synaptic plasticity. These results imply that altering the gut microbiota through symbiotic supplementation may be an effective approach to prevent or mitigate diabetes-associated cognitive decline. Show less

Many membrane proteins, including G protein-coupled receptors (GPCRs), are susceptible to denaturation when extracted from their native membrane by detergents. Therefore, alternative methods have been developed, including amphiphilic copolymers that enable the direct extraction of functional membrane proteins along with their surrounding lipids. Among these amphiphilic copolymers, styrene/maleic acid (SMA) and diisobutylene/maleic acid (DIBMA) polymers have been extensively studied. Despite their many benefits, SMA and DIBMA polymers also have considerable drawbacks limiting their applications. Herein, we describe a series of new amphiphilic copolymers derived from DIBMA via partial amidation of the carboxylate pendant groups with various biocompatible amines. We characterize the new polymer's nanodisc-forming properties and ability to extract the melanocortin 4 receptor (MC Show less

Familial chylomicronemia syndrome (FCS) is an ultra-rare disorder associated with pathogenic variants in genes implicated in chylomicron metabolism such as LPL, APOA5, APOC2, GPIHBP1, and LMF1. Patients with FCS have severe hypertriglyceridemia complicated with recurrent episodes of pancreatitis. Volanesorsen is a treatment option for such patients. However, this treatment is not approved or available in all countries. To present the real-life evidence of clinical response to volanesorsen in patients with FCS in Colombia. All patients treated with volanesorsen in Colombia as of June 25, 2024, were included. After informed consent, relevant clinical and laboratory data were obtained through review of clinical charts and records from the volanesorsen patient support program. Ten patients with FCS and treated with volanesorsen were included. Most cases were caused by variants in LPL. A total of 90% of cases had at least 1 episode of pancreatis, the mean number of pancreatitis episodes was 5. Median follow-up was 56.5 weeks (IQR 38.3-82.3). The median highest plasma triglyceride (TG) level before treatment was 3111 mg/dL (IQR 1738-3810), while the median lowest TG level after treatment was 493 mg/dL (IQR 147-812). The mean percent decreases in plasma TG at months 1, 3, 6, and 12 were 53.6%, 59.7%, 51.5%, and 40.5%, respectively. There were no new pancreatitis episodes after initiation of volanesorsen treatment. Side effects were consistent with those reported in clinical trials. Real-life data of volanesorsen treatment for FCS in Colombia demonstrate efficacy and safety similar to pivotal clinical trials. Show less

Patients with metabolic syndrome and heart failure (HF) often have accompanying kidney dysfunction, which was recently defined as cardiovascular-kidney-metabolic (CKM) syndrome. Prior metabolomics profiling of metabolic syndrome patients identified a plasma branched chain amino acid (BCAA) signature, and BCAAs themselves are elevated in the myocardium of patients with HF, potentially due to a defect in BCAA catabolic breakdown. The rate limiting step of BCAA catabolism is the decarboxylation by the enzyme branched chain ketoacid dehydrogenase (BCKDH), which is negatively regulated by BCKDH kinase (BCKDK or BDK), and BDK inhibitors improve metabolism and heart failure preclinically. Here, using two pre-clinical CKM models, the hyperphagic ZSF1 obese rat and the uninephrectomized SDT fatty rat with high salt drinking water, we applied unbiased proteomic, transcriptomic and metabolomic profiling to assess overall kidney gene expression and mitochondrial function. We show that BCAA catabolic impairment is associated with and may be causal to CKM and demonstrated impairment in BCAA catabolism within ZSF1 obese rat kidneys. In both CKM animal models, treatment with the BDK inhibitor BT2 improved urine protein content, kidney hypertrophy, and kidney pathology. Furthermore, coadministration of BT2 and the sodium-glucose cotransporter-2 inhibitor empagliflozin demonstrated additive effects to improve kidney parameters, kidney gene expression signatures, and kidney mitochondrial density and function. Our study suggests that in addition to its previously reported beneficial effects on metabolism and cardiac function, BDK inhibition may also improve kidney health and therefore could represent a new therapeutic avenue for CKM. Show less

Proteolytic processing of amyloid protein precursor by β-site secretase enzyme (BACE1) is dependent on the cellular lipid composition and is affected by endomembrane trafficking in dementia and Alzheimer's disease (AD). Stearoyl-CoA desaturase 1 (SCD1) is responsible for the synthesis of fatty acid monounsaturation (MUFAs), whose accumulation is strongly associated with cognitive dysfunction. In this study, we analyzed the relationship between BACE1 and SCD1 Our findings showed that BACE1 and SCD1 immunoreactivities were increased and colocalized in astrocytes of the hippocampus in a rat model of global cerebral ischemia (2-VO). A synergistic effect of double BACE1/SCD1 silencing on the recovery of motor and cognitive functions was obtained. This neuroprotective regulation involved the segregation of phospholipids (PLs) associated with polyunsaturated fatty acids in the hippocampus, cerebrospinal fluid, and serum. The double silencing in the sham and ischemic groups was stronger in the serum, inducing an inverse ratio between total phosphatydilcholine (PC) and lysophosphatidylcholine (LPC), represented mainly by the reduction of PC 38:4 and PC 36:4 and an increase in LPC 16:0 and LPC 18:0. Furthermore, PC 38:4 and PC:36:4 levels augmented in pathological conditions in Therefore, the findings suggest a novel convergence of BACE-1 and SCD1 in neurodegeneration, related to pro-inflammatory phospholipids. Show less

Beef cattle affected by feet and legs malformations (FLM) cannot perform their productive and reproductive functions satisfactorily, resulting in significant economic losses. Accelerated weight gain in young animals due to increased fat deposition can lead to ligaments, tendon and joint strain and promote gene expression patterns that lead to changes in the normal architecture of the feet and legs. The possible correlated response in the FLM due to yearling weight (YW) selection suggest that this second trait could be used as an indirect selection criterion. Therefore, FLM breeding values and the genetic correlation between FLM and yearling weight (YW) were estimated for 295,031 Nellore animals by fitting a linear-threshold model in a Bayesian approach. A genome-wide association study was performed to identify genomic windows and positional candidate genes associated with FLM. The effects of single nucleotide polymorphisms (SNPs) on FLM phenotypes (affected or unaffected) were estimated using the weighted single-step genomic BLUP method, based on genotypes of 12,537 animals for 461,057 SNPs. Twelve non-overlapping windows of 20 adjacent SNPs explaining more than 1% of the additive genetic variance were selected for candidate gene annotation. Functional and gene prioritization analysis of candidate genes identified six genes ( Show less

Both genetic background and diet are important determinants of cardiovascular diseases (CVD). Understanding gene-diet interactions could help improve CVD prevention and prognosis. We aimed to summarise the evidence on gene-diet interactions and CVD outcomes systematically. We searched MEDLINE We included 59 articles based on data from 29 studies; six articles involved multiple studies, and seven did not report details of their source population. The median sample size of the articles was 2562 participants. Of the 59 articles, 21 (35.6%) were qualified as high quality, while the rest were intermediate or poor. Eleven (18.6%) articles adjusted for multiple comparisons, four (7.0%) attempted to replicate the findings, 18 (30.5%) were based on Han-Chinese ethnicity, and 29 (49.2%) did not present Minor Allele Frequency. Fifty different dietary exposures and 52 different genetic factors were investigated, with alcohol intake and ADH1C variants being the most examined. Of 266 investigated diet-gene interaction tests, 50 (18.8%) were statistically significant, including CETP-TaqIB and ADH1C variants, which interacted with alcohol intake on CHD risk. However, interactions effects were significant only in some articles and did not agree on the direction of effects. Moreover, most of the studies that reported significant interactions lacked replication. Overall, the evidence on gene-diet interactions on CVD is limited, and lack correction for multiple testing, replication and sample size consideration. Show less

Urea cycle disorders (UCD) are a group of genetic diseases caused by deficiencies in the enzymes and transporters involved in the urea cycle. The impairment of the cycle results in ammonia accumulation, leading to neurological dysfunctions and poor outcomes to affected patients. The aim of this study is to investigate and describe UCD patients' principal clinical and biochemical presentations to support professionals on urgent diagnosis and quick management, aiming better outcomes for patients. We explored medical records of 30 patients diagnosed in a referral center from Brazil to delineate UCD clinical and biochemical profile. Patients demonstrated a range of signs and symptoms, such as altered levels of consciousness, acute encephalopathy, seizures, progressive loss of appetite, vomiting, coma, and respiratory distress, in most cases combined with high levels of ammonia, which is an immediate biomarker, leading to a UCD suspicion. The most prevalent UCD detected were ornithine transcarbamylase deficiency, followed by citrullinemia type 1, hyperargininemia, carbamoyl phosphate synthase 1 deficiency, and argininosuccinic aciduria. Clinical symptoms were highly severe, being the majority developmental and neurological disabilities, with 20% of death rate. Laboratory analysis revealed high levels of ammonia (mean ± SD: 860 ± 470 μmol/L; reference value: ≤80 μmol/L), hypoglycemia, metabolic acidosis, and high excretion of orotic acid in the urine (except in carbamoyl phosphate synthetase 1 [CPS1] deficiency). We emphasize the need of urgent identification of UCD clinical and biochemical conditions, and immediate measurement of ammonia, to enable the correct diagnosis and increase the chances of patients' survival, minimizing neurological and psychomotor damage caused by hepatic encephalopathy. Show less

This study aimed to evaluate genetic contributions to sudden unexpected death in pediatrics (SUDP). We phenotyped and performed exome sequencing for 352 SUDP cases. We analyzed variants in 294 "SUDP genes" with mechanisms plausibly related to sudden death. In a subset of 73 cases with parental data (trios), we performed exome-wide analyses and conducted cohort-wide burden analyses. In total, we identified likely contributory variants in 37 of 352 probands (11%). Analysis of SUDP genes identified pathogenic/likely pathogenic variants in 12 of 352 cases (SCN1A, DEPDC5 [2], GABRG2, SCN5A [2], TTN [2], MYBPC3, PLN, TNNI3, and PDHA1) and variants of unknown significance-favor-pathogenic in 17 of 352 cases. Exome-wide analyses of the 73 cases with family data additionally identified 4 de novo pathogenic/likely pathogenic variants (SCN1A [2], ANKRD1, and BRPF1) and 4 de novo variants of unknown significance-favor-pathogenic. Comparing cases with controls, we demonstrated an excess burden of rare damaging SUDP gene variants (odds ratio, 2.94; 95% confidence interval, 2.37-4.21) and of exome-wide de novo variants in the subset of 73 with trio data (odds ratio, 3.13; 95% confidence interval, 1.91-5.16). We provide strong evidence for a role of genetic factors in SUDP, involving both candidate genes and novel genes for SUDP and expanding phenotypes of disease genes not previously associated with sudden death. Show less

Nek2 (NIMA-related kinase 2) is a serine/threonine-protein kinase that localizes to centrosomes and kinetochores, controlling centrosome separation, chromosome attachments to kinetochores, and the spindle assembly checkpoint. These processes prevent centrosome amplification (CA), mitotic dysfunction, and chromosome instability (CIN). Our group and others have suggested that Nek2 maintains high levels of CA/CIN, tumor growth, and drug resistance. We identified that Nek2 overexpression correlates with poor survival of breast cancer. However, the mechanisms driving these phenotypes are unknown. We now report that overexpression of Nek2 in MCF10A cells drives CA/CIN and aneuploidy. Besides, enhanced levels of Nek2 results in larger 3D acinar structures, but could not initiate tumors in a p53 Show less

Subclinical atherosclerosis (sCVD), measured by coronary artery calcium (CAC) and carotid intima media thickness (CIMT) is associated with cardiovascular disease (CVD). Genome-Wide Association Studies (GWAS) of sCVD and CVD have focused primarily on Caucasian populations. We hypothesized that these associations may differ in populations from distinct genetic backgrounds. The associations between sCVD and 66 single nucleotide polymorphisms (SNPs) from published GWAS of sCVD and CVD were tested in 8224 Multi-Ethnic Study of Atherosclerosis (MESA) and MESA Family participants [2329 Caucasians (EUA), 691 Chinese (CHN), 2482 African Americans (AFA), and 2012 Hispanic (HIS)] using an additive model adjusting for CVD risk factors, with SNP significance defined by a Bonferroni-corrected p < 7.6 × 10(-4) (0.05/66). In EUA there were significant associations for CAC with SNPs in 9p21 (rs1333049, P = 2 × 10(-9); rs4977574, P = 4 × 10(-9)), COL4A1 (rs9515203, P = 9 × 10(-6)), and PHACTR1 (rs9349379, P = 4 × 10(-4)). In HIS, CAC was associated with SNPs in 9p21 (rs1333049, P = 8 × 10(-5); rs4977574, P = 5 × 10(-5)), APOA5 (rs964184, P = 2 × 10(-4)), and ADAMTS7 (rs7173743, P = 4 × 10(-4)). There were no associations between CAC and 9p21 SNPs for AFA and CHN. Fine mapping of the 9p21 region revealed SNPs with robust associations with CAC in EUA and HIS but no significant associations in AFA and CHN. Our results suggest some shared genetic architecture for sCVD across ethnic groups, while also underscoring the possibility of novel variants and/or pathways in risk of CVD in ethnically diverse populations. Show less

The calcium/calmodulin-dependent protein phosphatase calcineurin is required for the induction of transcriptional events that initiate and promote myogenic differentiation. An important effector for calcineurin in striated muscle is the transcription factor myocyte enhancer factor 2 (MEF2). The targeting of the enzyme and substrate to specific intracellular compartments by scaffold proteins often confers specificity in phosphatase activity. We now show that the scaffolding protein mAKAP organizes a calcineurin/MEF2 signaling complex in myocytes, regulating gene transcription. A calcineurin/mAKAP/MEF2 complex can be isolated from C2C12 cells and cardiac myocytes, and the calcineurin/MEF2 association is dependent on mAKAP expression. We have identified a peptide comprising the calcineurin binding domain in mAKAP that can disrupt the binding of the phosphatase to the scaffold in vivo. Dominant interference of calcineurin/mAKAP binding blunts the increase in MEF2 transcriptional activity seen during myoblast differentiation, as well as the expression of endogenous MEF2-target genes. Furthermore, disruption of calcineurin binding to mAKAP in cardiac myocytes inhibits adrenergic-induced cellular hypertrophy. Together these data illustrate the importance of calcineurin anchoring by the mAKAP scaffold for MEF2 regulation. Show less

Itraconazole (ITZ) is an approved antifungal agent that carries a "black box warning" in its label regarding a risk of negative cardiac inotropy based on clinical findings. Since the mechanism of the negative inotropic effect is unknown, we performed a variety of preclinical and mechanistic studies to explore the pharmacological profile of ITZ and understand the negative inotropic mechanism. ITZ was evaluated in: (1) an isolated rabbit heart (IRH) preparation using Langendorff retrograde perfusion; (2) ion channel studies; (3) a rat heart mitochondrial function profiling screen; (4) a mitochondrial membrane potential (MMP) assay; (5) in vitro pharmacology profiling assays (148 receptors, ion channels, transporters, and enzymes); and (6) a kinase selectivity panel (451 kinases). In the IRH, ITZ decreased cardiac contractility (>30%) at 0.3μM, with increasing effect at higher concentrations, which indicated a direct negative inotropic effect upon the heart. It also decreased heart rate and coronary flow (≥1μM) and prolonged PR/QRS intervals (3μM). In mechanistic studies, ITZ inhibited the cardiac NaV channel (IC50: 4.2μM) and was devoid of any functional inhibitory effect at the remaining pharmacological targets. Lastly, ITZ did not affect MMP, nor interfere with mitochondrial enzymes or processes involved with fuel substrate utilization or energy formation. Overall, the cardiovascular and mechanistic data suggest that ITZ-induced negative inotropy is a direct effect on the heart, in addition, the potential involvement of mitochondria function and L-type Ca(2+) channels are eliminated. The exact mechanism underlying the negative inotropy is uncertain, and requires further study. Show less

Differentiation of skeletal myoblast cells to functional myotubes involves highly regulated transcriptional dynamics. The myocyte enhancer factor 2 (MEF2) transcription factors are critical to this process, synergizing with the master regulator MyoD to promote muscle specific gene transcription. MEF2 is extensively regulated by myogenic stimuli, both transcriptionally and post-translationally, but to date there has been little progress in understanding how signals upstream of MEF2 are coordinated to produce a coherent response. In this study, we define a novel interaction between the muscle A-kinase anchoring protein (mAKAP) and MEF2 in skeletal muscle. Discrete domains of MEF2 and mAKAP bind directly. Their interaction was exploited to probe the function of mAKAP-tethered MEF2 during myogenic differentiation. Dominant interference of MEF2/mAKAP binding was sufficient to block MEF2 activation during the early stages of differentiation. Furthermore, extended expression of this disrupting domain effectively blocked myogenic differentiation, halting the formation of myotubes and decreasing expression of several differentiation markers. This study expands our understanding of the regulation of MEF2 in skeletal muscle and identifies the mAKAP scaffold as a facilitator of MEF2 transcription and myogenic differentiation. Show less