SCUBE3 loss-of-function causes a recognizable recessive developmental disorder due to defective bone morphogenetic protein signaling.

Signal peptide-CUB-EGF domain-containing protein 3 (SCUBE3) is a member of a small family of multifunctional cell surface-anchored glycoproteins functioning as co-receptors for a variety of growth factors. Here we report that bi-allelic inactivating variants in SCUBE3 have pleiotropic consequences on development and cause a previously unrecognized syndromic disorder. Eighteen affected individuals from nine unrelated families showed a consistent phenotype characterized by reduced growth, skeletal features, distinctive craniofacial appearance, and dental anomalies. In vitro functional validation studies demonstrated a variable impact of disease-causing variants on transcript processing, protein secretion and function, and their dysregulating effect on bone morphogenetic protein (BMP) signaling. We show that SCUBE3 acts as a BMP2/BMP4 co-receptor, recruits the BMP receptor complexes into raft microdomains, and positively modulates signaling possibly by augmenting the specific interactions between BMPs and BMP type I receptors. Scube3-/- mice showed craniofacial and dental defects, reduced body size, and defective endochondral bone growth due to impaired BMP-mediated chondrogenesis and osteogenesis, recapitulating the human disorder. Our findings identify a human disease caused by defective function of a member of the SCUBE family, and link SCUBE3 to processes controlling growth, morphogenesis, and bone and teeth development through modulation of BMP signaling.

Genetic deletion of hepatic NCOR1 protects from atherosclerosis by promoting alternative bile acid-metabolism and sterol excretion.

BACKGROUND: The nuclear receptor corepressor 1 (NCOR1) plays an important role in the regulation of gene expression in immunometabolic conditions by connecting chromatin-modifying enzymes, coregulators and transcription factors. NCOR1 has been shown to be involved in cardiometabolic diseases. Recently, we demonstrated that the deletion of macrophage NCOR1 aggravates atherosclerosis by promoting CD36-triggered foam cell formation via PPARG derepression. PURPOSE: Since NCOR1 modulates the function of several key regulators involved in hepatic lipid and bile acid metabolism, we hypothesized that its deletion in hepatocytes alters lipid metabolism and atherogenesis. METHODS: To test this hypothesis, we generated hepatocyte-specific Ncor1 knockout mice on a Ldlr-/- background. Besides assessing the progression of the disease in thoracoabdominal aortae en face, we analyzed hepatic cholesterol and bile acid metabolism at expression and functional levels. RESULTS: Our data demonstrate that liver-specific Ncor1 knockout mice on an atherosclerosis-prone background develop less atherosclerotic lesions than controls. Interestingly, under chow diet, plasma cholesterol levels of liver-specific Ncor1 knockout mice were slightly higher compared to control, but strongly reduced compared to control mice after feeding them an atherogenic diet for 12 weeks. Moreover, the hepatic cholesterol content was decreased in liver-specific Ncor1 knockout compared to control mice. Our mechanistic data revealed that NCOR1 reprograms the synthesis of bile acids towards the alternative pathway, which in turn reduce bile hydrophobicity and enhances fecal cholesterol excretion. CONCLUSIONS: Our data suggest that hepatic Ncor1 deletion in mice decreases atherosclerosis development by reprograming bile acid metabolism and enhancing fecal cholesterol excretion.

Antiphospholipid syndrome-mediated acute cerebrovascular diseases and long-term outcomes.

OBJECTIVES: The antiphospholipid syndrome (APS) is an autoimmune disease associated with thrombotic and non-thrombotic neurologic manifestations. APS is classified as primary (PAPS) or secondary (SAPS) when it co-exists with another autoimmune disease. We aim to describe the spectrum of acute cerebrovascular disease among patients with APS, their differences between stroke subtypes, and long-term functional outcomes. METHODS: Retrospective cohort study including adult (≥18 years) patients with APS followed in the stroke clinic of a tertiary-care reference center for autoimmune diseases in Mexico from 2009 to 2019. RESULTS: We studied 120 cases; 99 (82.5%) women; median age 43 years (interquartile range 35-52); 63.3% with SAPS. Demographics, comorbidities, and antiphospholipid antibodies (aPL) positivity were similar between APS type and stroke subtypes. Amongst index events, we observed 84 (70%) acute ischemic strokes (AIS), 19 (15.8%) cerebral venous thromboses (CVT), 11 (9.2%) intracerebral hemorrhages (ICH), and six (5%) subarachnoid hemorrhages (SAH). Sixty-seven (55.8%) were known patients with APS; the median time from APS diagnosis to index stroke was 46 months (interquartile range 12-96); 64.7% of intracranial hemorrhages (ICH or SAH) occurred ≥4 years after APS was diagnosed (23.5% anticoagulation-related); 63.2% of CVT cases developed before APS was diagnosed or simultaneously. Recurrences occurred in 26 (22.8%) patients, AIS, in 18 (69.2%); intracranial hemorrhage, in eight (30.8%). Long-term functional outcomes were good (modified Rankin Scale ≤2) in 63.2% of cases, during follow-up, the all-cause mortality rate was 19.2%. CONCLUSION: We found no differences between stroke subtypes and APS types. aPL profiles were not associated with any of the acute cerebrovascular diseases described in this cohort. CVT may be an initial thrombotic manifestation of APS with low mortality and good long-term functional outcome.

Macrophage NCOR1 protects from atherosclerosis by repressing a pro-atherogenic PPARγ signature.

AIMS: Nuclear receptors and their cofactors regulate key pathophysiological processes in atherosclerosis development. The transcriptional activity of these nuclear receptors is controlled by the nuclear receptor corepressors (NCOR), scaffolding proteins that form the basis of large corepressor complexes. Studies with primary macrophages demonstrated that the deletion of Ncor1 increases the expression of atherosclerotic molecules. However, the role of nuclear receptor corepressors in atherogenesis is unknown. METHODS AND RESULTS: We generated myeloid cell-specific Ncor1 knockout mice and crossbred them with low-density lipoprotein receptor (Ldlr) knockouts to study the role of macrophage NCOR1 in atherosclerosis. We demonstrate that myeloid cell-specific deletion of nuclear receptor corepressor 1 (NCOR1) aggravates atherosclerosis development in mice. Macrophage Ncor1-deficiency leads to increased foam cell formation, enhanced expression of pro-inflammatory cytokines, and atherosclerotic lesions characterized by larger necrotic cores and thinner fibrous caps. The immunometabolic effects of NCOR1 are mediated via suppression of peroxisome proliferator-activated receptor gamma (PPARγ) target genes in mouse and human macrophages, which lead to an enhanced expression of the CD36 scavenger receptor and subsequent increase in oxidized low-density lipoprotein uptake in the absence of NCOR1. Interestingly, in human atherosclerotic plaques, the expression of NCOR1 is reduced whereas the PPARγ signature is increased, and this signature is more pronounced in ruptured compared with non-ruptured carotid plaques. CONCLUSIONS: Our findings show that macrophage NCOR1 blocks the pro-atherogenic functions of PPARγ in atherosclerosis and suggest that stabilizing the NCOR1-PPARγ binding could be a promising strategy to block the pro-atherogenic functions of plaque macrophages and lesion progression in atherosclerotic patients.

Stroke in systemic lupus erythematosus: epidemiology, mechanism, and long-term outcome.

OBJECTIVE: To determine stroke prevalence, mechanisms, and long-term outcome in a cohort of Hispanic patients with systemic lupus erythematosus (SLE). METHODS: We analyzed demographical data, the timing between SLE diagnosis and stroke onset, stroke type, recurrence, and outcomes from an institutional database of 4451 patients with SLE followed from 1993 to 2018. RESULTS: We observed 139 strokes (3.1%), for an incidence rate of 1.25 per 1000 person-years: 81 (58.3%) acute ischemic stroke (AIS), 19 (13.7%) subarachnoid hemorrhage (SAH), 17 (12.2%) cerebral venous thrombosis, 13 (9.4%) intracerebral hemorrhage (ICH), and 9 (6.5%) transient ischemic attack. Median time from SLE diagnosis to acute stroke was 60 months (interquartile range 12-132 months). AIS had a bimodal presentation with 26% occurring within the first year and 30% >10 years after SLE diagnosis. In contrast, 75% of ICH cases occurred >3 years (and 34% >10 years) after SLE diagnosis. The most important cause of AIS was secondary antiphospholipid syndrome (48%). Hypertension was associated with 69% of ICH cases, while aneurysmal rupture was observed in 78% of SAH cases. Excellent recovery at hospital discharge was observed in 65%. Stroke recurrence was observed in 7%. The long-term all-cause fatality rate was 8%. CONCLUSIONS: The prevalence of stroke in this cohort was 3.1%. Ischemic strokes had a bimodal presentation, occurring either early after SLE diagnosis or after a several-year delay. Half of the hemorrhagic strokes occurred >10 years after the diagnosis of SLE. Clinical outcome was usually good with a relatively low recurrence rate.

Unravelling Endogenous MicroRNA System Dysfunction as a New Pathophysiological Mechanism in Machado-Joseph Disease.

Machado-Joseph disease (MJD) is a genetic neurodegenerative disease caused by an expanded polyglutamine tract within the protein ataxin-3 (ATXN3). Despite current efforts, MJD's mechanism of pathogenesis remains unclear and no disease-modifying treatment is available. Therefore, in this study, we investigated (1) the role of the 3' UTR of ATXN3, a putative microRNA (miRNA) target, (2) whether miRNA biogenesis and machinery are dysfunctional in MJD, and (3) which specific miRNAs target ATXN3-3' UTR and whether they can alleviate MJD neuropathology in vivo. Our results demonstrate that endogenous miRNAs, by targeting sequences in the 3' UTR, robustly reduce ATXN3 expression and aggregation in vitro and neurodegeneration and neuroinflammation in vivo. Importantly, we found an abnormal MJD-associated downregulation of genes involved in miRNA biogenesis and silencing activity. Finally, we identified three miRNAs-mir-9, mir-181a, and mir-494-that interact with the ATXN3-3' UTR and whose expression is dysregulated in human MJD neurons and in other MJD cell and animal models. Furthermore, overexpression of these miRNAs in mice resulted in reduction of mutATXN3 levels, aggregate counts, and neuronal dysfunction. Altogether, these findings indicate that endogenous miRNAs and the 3' UTR of ATXN3 play a crucial role in MJD pathogenesis and provide a promising opportunity for MJD treatment.

Understanding the pathogenetic mechanisms underlying altered neuronal function associated with CAMK2B mutations.

'Dominant mutations in CAMK2B, encoding a subunit of the calcium/calmodulin-dependent protein kinase II (CAMK2), a serine/threonine kinase playing a key role in synaptic plasticity, learning and memory, underlie a recently characterized neurodevelopmental disorder (MRD54) characterized by delayed psychomotor development, mild to severe intellectual disability, hypotonia, and behavioral abnormalities. Targeted therapies to treat MRD54 are currently unavailable. In this review, we revise current knowledge on the molecular and cellular mechanisms underlying the altered neuronal function associated with defective CAMKIIß function. We also summarize the identified genotype-phenotype correlations and discuss the disease models that have been generated to profile the altered neuronal phenotype and understand the pathophysiology of this disease.

Chemical regulation of the cGAS-STING pathway.

Nucleic acids represent a major class of pathogen and damage signatures, recognized by a variety of host sensors to initiate signaling cascades and immune responses, such as mechanisms of RLR-MAVS, cGAS-STING, TLR-TRIF, and AIM2 inflammasome. Yet, an outstanding challenge is understanding how nucleic acid sensing initiates immune responses and its tethering in various infectious, cancerous, autoimmune, and inflammatory diseases. However, the discovery and application of a plethora of small molecule compounds have substantially facilitated this process. This review provides an overview and recent development of the innate DNA-sensing pathway of cGAS-STING and highlights the multiple agonists and inhibitors in fine-tuning the pathway that can be exploited to improve disease treatment, focusing primarily on crucial pathway components and regulators.

α-Synuclein Responses in the Laterodorsal Tegmentum, the Pedunculopontine Tegmentum, and the Substantia Nigra: Implications for Early Appearance of Sleep Disorders in Parkinson's Disease.

BACKGROUND: Parkinson's disease (PD) is a neurodegenerative disorder associated with insoluble pathological aggregates of the protein α-synuclein. While PD is diagnosed by motor symptoms putatively due to aggregated α-synuclein-mediated damage to substantia nigra (SN) neurons, up to a decade before motor symptom appearance, patients exhibit sleep disorders (SDs). Therefore, we hypothesized that α-synuclein, which can be present in monomeric, fibril, and other forms, has deleterious cellular actions on sleep-control nuclei. OBJECTIVE: We investigated whether native monomer and fibril forms of α-synuclein have effects on neuronal function, calcium dynamics, and cell-death-induction in two sleep-controlling nuclei: the laterodorsal tegmentum (LDT), and the pedunculopontine tegmentum (PPT), as well as the motor-controlling SN. METHODS: Size exclusion chromatography, Thioflavin T fluorescence assays, and circular dichroism spectroscopy were used to isolate structurally defined forms of recombinant, human α-synuclein. Neuronal and viability effects of characterized monomeric and fibril forms of α-synuclein were determined on LDT, PPT, and SN neurons using electrophysiology, calcium imaging, and neurotoxicity assays. RESULTS: In LDT and PPT neurons, both forms of α-synuclein induced excitation and increased calcium, and the monomeric form heightened putatively excitotoxic neuronal death, whereas, in the SN, we saw inhibition, decreased intracellular calcium, and monomeric α-synuclein was not associated with heightened cell death. CONCLUSION: Nucleus-specific differential effects suggest mechanistic underpinnings of SDs' prodromal appearance in PD. While speculative, we hypothesize that the monomeric form of α-synuclein compromises functionality of sleep-control neurons, leading to the presence of SDs decades prior to motor dysfunction.

Modulation of the Mechanisms Driving Transthyretin Amyloidosis.

Transthyretin (TTR) amyloidoses are systemic diseases associated with TTR aggregation and extracellular deposition in tissues as amyloid. The most frequent and severe forms of the disease are hereditary and associated with amino acid substitutions in the protein due to single point mutations in the TTR gene (ATTRv amyloidosis). However, the wild type TTR (TTR wt) has an intrinsic amyloidogenic potential that, in particular altered physiologic conditions and aging, leads to TTR aggregation in people over 80 years old being responsible for the non-hereditary ATTRwt amyloidosis. In normal physiologic conditions TTR wt occurs as a tetramer of identical subunits forming a central hydrophobic channel where small molecules can bind as is the case of the natural ligand thyroxine (T4). However, the TTR amyloidogenic variants present decreased stability, and in particular conditions, dissociate into partially misfolded monomers that aggregate and polymerize as amyloid fibrils. Therefore, therapeutic strategies for these amyloidoses may target different steps in the disease process such as decrease of variant TTR (TTRv) in plasma, stabilization of TTR, inhibition of TTR aggregation and polymerization or disruption of the preformed fibrils. While strategies aiming decrease of the mutated TTR involve mainly genetic approaches, either by liver transplant or the more recent technologies using specific oligonucleotides or silencing RNA, the other steps of the amyloidogenic cascade might be impaired by pharmacologic compounds, namely, TTR stabilizers, inhibitors of aggregation and amyloid disruptors. Modulation of different steps involved in the mechanism of ATTR amyloidosis and compounds proposed as pharmacologic agents to treat TTR amyloidosis will be reviewed and discussed.

Molecular Mechanisms of Acute Oxygen Sensing by Arterial Chemoreceptor Cells. Role of Hif2α.

Carotid body glomus cells are multimodal arterial chemoreceptors able to sense and integrate changes in several physical and chemical parameters in the blood. These cells are also essential for O2 homeostasis. Glomus cells are prototypical peripheral O2 sensors necessary to detect hypoxemia and to elicit rapid compensatory responses (hyperventilation and sympathetic activation). The mechanisms underlying acute O2 sensing by glomus cells have been elusive. Using a combination of mouse genetics and single-cell optical and electrophysiological techniques, it has recently been shown that activation of glomus cells by hypoxia relies on the generation of mitochondrial signals (NADH and reactive oxygen species), which modulate membrane ion channels to induce depolarization, Ca2+ influx, and transmitter release. The special sensitivity of glomus cell mitochondria to changes in O2 tension is due to Hif2α-dependent expression of several atypical mitochondrial subunits, which are responsible for an accelerated oxidative metabolism and the strict dependence of mitochondrial complex IV activity on O2 availability. A mitochondrial-to-membrane signaling model of acute O2 sensing has been proposed, which explains existing data and provides a solid foundation for future experimental tests. This model has also unraveled new molecular targets for pharmacological modulation of carotid body activity potentially relevant in the treatment of highly prevalent medical conditions.

Protein function in precision medicine: deep understanding with machine learning.

Precision medicine and personalized health efforts propose leveraging complex molecular, medical and family history, along with other types of personal data toward better life. We argue that this ambitious objective will require advanced and specialized machine learning solutions. Simply skimming some low-hanging results off the data wealth might have limited potential. Instead, we need to better understand all parts of the system to define medically relevant causes and effects: how do particular sequence variants affect particular proteins and pathways? How do these effects, in turn, cause the health or disease-related phenotype? Toward this end, deeper understanding will not simply diffuse from deeper machine learning, but from more explicit focus on understanding protein function, context-specific protein interaction networks, and impact of variation on both.