Structure, Function, and Regulation of the Junctophilin Family.

In both excitable and nonexcitable cells, diverse physiological processes are linked to different calcium microdomains within nanoscale junctions that form between the plasma membrane and endo-sarcoplasmic reticula. It is now appreciated that the junctophilin protein family is responsible for establishing, maintaining, and modulating the structure and function of these junctions. We review foundational findings from more than two decades of research that have uncovered how junctophilin-organized ultrastructural domains regulate evolutionarily conserved biological processes. We discuss what is known about the junctophilin family of proteins. Our goal is to summarize the current knowledge of junctophilin domain structure, function, and regulation and to highlight emerging avenues of research that help our understanding of the transcriptional, translational, and post-translational regulation of this gene family and its roles in health and during disease.

ERK inhibition rescues defects in fate specification of Nf1-deficient neural progenitors and brain abnormalities.

Germline mutations in the RAS/ERK signaling pathway underlie several related developmental disorders collectively termed neuro-cardio-facial-cutaneous (NCFC) syndromes. NCFC patients manifest varying degrees of cognitive impairment, but the developmental basis of their brain abnormalities remains largely unknown. Neurofibromatosis type 1 (NF1), an NCFC syndrome, is caused by loss-of-function heterozygous mutations in the NF1 gene, which encodes neurofibromin, a RAS GTPase-activating protein. Here, we show that biallelic Nf1 inactivation promotes Erk-dependent, ectopic Olig2 expression specifically in transit-amplifying progenitors, leading to increased gliogenesis at the expense of neurogenesis in neonatal and adult subventricular zone (SVZ). Nf1-deficient brains exhibit enlarged corpus callosum, a structural defect linked to severe learning deficits in NF1 patients. Strikingly, these NF1-associated developmental defects are rescued by transient treatment with an MEK/ERK inhibitor during neonatal stages. This study reveals a critical role for Nf1 in maintaining postnatal SVZ-derived neurogenesis and identifies a potential therapeutic window for treating NF1-associated brain abnormalities.

Structural basis and evolution of the photosystem I-light-harvesting supercomplex of cryptophyte algae.

Cryptophyte plastids originated from a red algal ancestor through secondary endosymbiosis. Cryptophyte photosystem I (PSI) associates with transmembrane alloxanthin-chlorophyll a/c proteins (ACPIs) as light-harvesting complexes (LHCs). Here, we report the structure of the photosynthetic PSI-ACPI supercomplex from the cryptophyte Chroomonas placoidea at 2.7-Å resolution obtained by crygenic electron microscopy. Cryptophyte PSI-ACPI represents a unique PSI-LHCI intermediate in the evolution from red algal to diatom PSI-LHCI. The PSI-ACPI supercomplex is composed of a monomeric PSI core containing 14 subunits, 12 of which originated in red algae, 1 diatom PsaR homolog, and an additional peptide. The PSI core is surrounded by 14 ACPI subunits that form 2 antenna layers: an inner layer with 11 ACPIs surrounding the PSI core and an outer layer containing 3 ACPIs. A pigment-binding subunit that is not present in any other previously characterized PSI-LHCI complexes, ACPI-S, mediates the association and energy transfer between the outer and inner ACPIs. The extensive pigment network of PSI-ACPI ensures efficient light harvesting, energy transfer, and dissipation. Overall, the PSI-LHCI structure identified in this study provides a framework for delineating the mechanisms of energy transfer in cryptophyte PSI-LHCI and for understanding the evolution of photosynthesis in the red lineage, which occurred via secondary endosymbiosis.

Preventing Site-Specific Calpain Proteolysis of Junctophilin-2 Protects Against Stress-Induced Excitation-Contraction Uncoupling and Heart Failure Development.

BACKGROUND: Excitation-contraction (E-C) coupling processes become disrupted in heart failure (HF), resulting in abnormal Ca2+ homeostasis, maladaptive structural and transcriptional remodeling, and cardiac dysfunction. Junctophilin-2 (JP2) is an essential component of the E-C coupling apparatus but becomes site-specifically cleaved by calpain, leading to disruption of E-C coupling, plasmalemmal transverse tubule degeneration, abnormal Ca2+ homeostasis, and HF. However, it is not clear whether preventing site-specific calpain cleavage of JP2 is sufficient to protect the heart against stress-induced pathological cardiac remodeling in vivo. METHODS: Calpain-resistant JP2 knock-in mice (JP2CR) were generated by deleting the primary JP2 calpain cleavage site. Stress-dependent JP2 cleavage was assessed through in vitro cleavage assays and in isolated cardiomyocytes treated with 1 µmol/L isoproterenol by immunofluorescence. Cardiac outcomes were assessed in wild-type and JP2CR mice 5 weeks after transverse aortic constriction compared with sham surgery using echocardiography, histology, and RNA-sequencing methods. E-C coupling efficiency was measured by in situ confocal microscopy. E-C coupling proteins were evaluated by calpain assays and Western blotting. The effectiveness of adeno-associated virus gene therapy with JP2CR, JP2, or green fluorescent protein to slow HF progression was evaluated in mice with established cardiac dysfunction. RESULTS: JP2 proteolysis by calpain and in response to transverse aortic constriction and isoproterenol was blocked in JP2CR cardiomyocytes. JP2CR hearts are more resistant to pressure-overload stress, having significantly improved Ca2+ homeostasis and transverse tubule organization with significantly attenuated cardiac dysfunction, hypertrophy, lung edema, fibrosis, and gene expression changes relative to wild-type mice. JP2CR preserves the integrity of calpain-sensitive E-C coupling-related proteins, including ryanodine receptor 2, CaV1.2, and sarcoplasmic reticulum calcium ATPase 2a, by attenuating transverse aortic constriction-induced increases in calpain activity. Furthermore, JP2CR gene therapy after the onset of cardiac dysfunction was found to be effective at slowing the progression of HF and superior to wild-type JP2. CONCLUSIONS: The data presented here demonstrate that preserving JP2-dependent E-C coupling by prohibiting the site-specific calpain cleavage of JP2 offers multifaceted beneficial effects, conferring cardiac protection against stress-induced proteolysis, hypertrophy, and HF. Our data also indicate that specifically targeting the primary calpain cleavage site of JP2 by gene therapy approaches holds great therapeutic potential as a novel precision medicine for treating HF.

IRS2 Signaling Protects Against Stress-Induced Arrhythmia by Maintaining Ca2+ Homeostasis.

BACKGROUND: The docking protein IRS2 (insulin receptor substrate protein-2) is an important mediator of insulin signaling and may also regulate other signaling pathways. Murine hearts with cardiomyocyte-restricted deletion of IRS2 (cIRS2-KO) are more susceptible to pressure overload-induced cardiac dysfunction, implying a critical protective role of IRS2 in cardiac adaptation to stress through mechanisms that are not fully understood. There is limited evidence regarding the function of IRS2 beyond metabolic homeostasis regulation, particularly in the context of cardiac disease. METHODS: A retrospective analysis of an electronic medical record database was conducted to identify patients with IRS2 variants and assess their risk of cardiac arrhythmias. Arrhythmia susceptibility was examined in cIRS2-KO mice. The underlying mechanisms were investigated using confocal calcium imaging of ex vivo whole hearts and isolated cardiomyocytes to assess calcium handling, Western blotting to analyze the involved signaling pathways, and pharmacological and genetic interventions to rescue arrhythmias in cIRS2-KO mice. RESULTS: The retrospective analysis identified patients with IRS2 variants of uncertain significance with a potential association to an increased risk of cardiac arrhythmias compared with matched controls. cIRS2-KO hearts were found to be prone to catecholamine-sensitive ventricular tachycardia and reperfusion ventricular tachycardia. Confocal calcium imaging of ex vivo whole hearts and single isolated cardiomyocytes from cIRS2-KO hearts revealed decreased Ca²+ transient amplitudes, increased spontaneous Ca²+ sparks, and reduced sarcoplasmic reticulum Ca²+ content during sympathetic stress, indicating sarcoplasmic reticulum dysfunction. We identified that overactivation of the AKT1/NOS3 (nitric oxide synthase 3)/CaMKII (Ca2+/calmodulin-dependent protein kinase II)/RyR2 (type 2 ryanodine receptor) signaling pathway led to calcium mishandling and catecholamine-sensitive ventricular tachycardia in cIRS2-KO hearts. Pharmacological AKT inhibition or genetic stabilization of RyR2 rescued catecholamine-sensitive ventricular tachycardia in cIRS2-KO mice. CONCLUSIONS: Cardiac IRS2 inhibits sympathetic stress-induced AKT/NOS3/CaMKII/RyR2 overactivation and calcium-dependent arrhythmogenesis. This novel IRS2 signaling axis, essential for maintaining cardiac calcium homeostasis under stress, presents a promising target for developing new antiarrhythmic therapies.

Ptpn23 Controls Cardiac T-Tubule Patterning by Promoting the Assembly of Dystrophin-Glycoprotein Complex.

BACKGROUND: Cardiac transverse tubules (T-tubules) are anchored to sarcomeric Z-discs by costameres to establish a regular spaced pattern. One of the major components of costameres is the dystrophin-glycoprotein complex (DGC). Nevertheless, how the assembly of the DGC coordinates with the formation and maintenance of T-tubules under physiological and pathological conditions remains unclear. METHODS: Given the known role of Ptpn23 (protein tyrosine phosphatase, nonreceptor type 23) in regulating membrane deformation, its expression in patients with dilated cardiomyopathy was determined. Taking advantage of Cre/Loxp, CRISPR/Cas9, and adeno-associated virus 9 (AAV9)-mediated in vivo gene editing, we generated cardiomyocyte-specific Ptpn23 and Actn2 (α-actinin-2, a major component of Z-discs) knockout mice. We also perturbed the DGC by using dystrophin global knockout mice (DmdE4*). MM 4-64 and Di-8-ANEPPS staining, Cav3 immunofluorescence, and transmission electron microscopy were performed to determine T-tubule structure in isolated cells and intact hearts. In addition, the assembly of the DGC with Ptpn23 and dystrophin loss of function was determined by glycerol-gradient fractionation and SDS-PAGE analysis. RESULTS: The expression level of Ptpn23 was reduced in failing hearts from dilated cardiomyopathy patients and mice. Genetic deletion of Ptpn23 resulted in disorganized T-tubules with enlarged diameters and progressive dilated cardiomyopathy without affecting sarcomere organization. AAV9-mediated mosaic somatic mutagenesis further indicated a cell-autonomous role of Ptpn23 in regulating T-tubule formation. Genetic and biochemical analyses showed that Ptpn23 was essential for the integrity of costameres, which anchor the T-tubule membrane to Z-discs, through interactions with α-actinin and dystrophin. Deletion of α-actinin altered the subcellular localization of Ptpn23 and DGCs. In addition, genetic inactivation of dystrophin caused similar T-tubule defects to Ptpn23 loss-of-function without affecting Ptpn23 localization at Z-discs. Last, inducible Ptpn23 knockout at 1 month of age showed Ptpn23 is also required for the maintenance of T-tubules in adult cardiomyocytes. CONCLUSIONS: Ptpn23 is essential for cardiac T-tubule formation and maintenance along Z-discs. During postnatal heart development, Ptpn23 interacts with sarcomeric α-actinin and coordinates the assembly of the DGC at costameres to sculpt T-tubule spatial patterning and morphology.

A novel class of xylanases specifically degrade marine red algal ß1,3/1,4-mixed-linkage xylan.

Xylans are polysaccharides composed of xylose and include ß1,4-xylan, ß1,3-xylan, and ß1,3/1,4-mixed-linkage xylan (MLX). MLX is widely present in marine red algae and constitutes a significant organic carbon in the ocean. Xylanases are hydrolase enzymes that play an important role in xylan degradation. While a variety of ß1,4-xylanases and ß1,3-xylanases involved in the degradation of ß1,4-xylan and ß1,3-xylan have been reported, no specific enzyme has yet been identified that degrades MLX. Herein, we report the characterization of a new MLX-specific xylanase from the marine bacterium Polaribacter sp. Q13 which utilizes MLX for growth. The bacterium secretes xylanases to degrade MLX, among which is Xyn26A, an MLX-specific xylanase that shows low sequence similarities (<27%) to ß1,3-xylanases in the glycoside hydrolase family 26 (GH26). We show that Xyn26A attacks MLX precisely at ß1,4-linkages, following a ß1,3-linkage toward the reducing end. We confirm that Xyn26A and its homologs have the same specificity and mode of action on MLX, and thus represent a new xylanase group which we term as MLXases. We further solved the structure of a representative MLXase, AlXyn26A. Structural and biochemical analyses revealed that the specificity of MLXases depends critically on a precisely positioned ß1,3-linkage at the -2/-1 subsite. Compared to the GH26 ß1,3-xylanases, we found MLXases have evolved a tunnel-shaped cavity that is fine-tuned to specifically recognize and hydrolyze MLX. Overall, this study offers a foremost insight into MLXases, shedding light on the biochemical mechanism of bacterial degradation of MLX.

ATF4-dependent increase in mitochondrial-endoplasmic reticulum tethering following OPA1 deletion in skeletal muscle.

Mitochondria and endoplasmic reticulum (ER) contact sites (MERCs) are protein- and lipid-enriched hubs that mediate interorganellar communication by contributing to the dynamic transfer of Ca2+, lipid, and other metabolites between these organelles. Defective MERCs are associated with cellular oxidative stress, neurodegenerative disease, and cardiac and skeletal muscle pathology via mechanisms that are poorly understood. We previously demonstrated that skeletal muscle-specific knockdown (KD) of the mitochondrial fusion mediator optic atrophy 1 (OPA1) induced ER stress and correlated with an induction of Mitofusin-2, a known MERC protein. In the present study, we tested the hypothesis that Opa1 downregulation in skeletal muscle cells alters MERC formation by evaluating multiple myocyte systems, including from mice and Drosophila, and in primary myotubes. Our results revealed that OPA1 deficiency induced tighter and more frequent MERCs in concert with a greater abundance of MERC proteins involved in calcium exchange. Additionally, loss of OPA1 increased the expression of activating transcription factor 4 (ATF4), an integrated stress response (ISR) pathway effector. Reducing Atf4 expression prevented the OPA1-loss-induced tightening of MERC structures. OPA1 reduction was associated with decreased mitochondrial and sarcoplasmic reticulum, a specialized form of ER, calcium, which was reversed following ATF4 repression. These data suggest that mitochondrial stress, induced by OPA1 deficiency, regulates skeletal muscle MERC formation in an ATF4-dependent manner.

CIB2 Is a Novel Endogenous Repressor of Atrial Remodeling.

BACKGROUND: Atrial fibrillation (AF) is a highly prevalent condition that can cause or exacerbate heart failure, is an important risk factor for stroke, and is associated with pronounced morbidity and death. Genes uniquely expressed in the atria are known to be essential for maintaining atrial structure and function. Atrial tissue remodeling contributes to arrhythmia recurrence and maintenance. However, the mechanism underlying atrial remodeling remains poorly understood. This study was designed to investigate whether other uncharacterized atrial specific genes play important roles in atrial physiology and arrhythmogenesis. METHODS: RNA-sequencing analysis was used to identify atrial myocyte specific and angiotensin II-responsive genes. Genetically modified, cardiomyocyte-specific mouse models (knockout and overexpression) were generated. In vivo and in vitro electrophysiological, histology, and biochemical analyses were performed to determine the consequences of CIB2 (calcium and integrin binding family member 2 protein) gain and loss of function in the atrium. RESULTS: Using RNA-sequencing analysis, we identified CIB2 as an atrial-enriched protein that is significantly downregulated in the left atria of patients with AF and mouse models of AF from angiotensin II infusion or pressure overload. Using cardiomyocyte-specific Cib2 knockout (Cib2-/-) and atrial myocyte-specific Cib2-overexpressing mouse models, we found that loss of Cib2 enhances AF occurrence, prolongs AF duration, and correlates with a significant increase in atrial fibrosis under stress. Conversely, Cib2 overexpression mitigates AF occurrence and atrial fibrosis triggered by angiotensin II stress. Mechanistically, we revealed that CIB2 competes with and inhibits CIB1-mediated calcineurin activation, thereby negating stress-induced structural remodeling and AF. CONCLUSIONS: Our data suggest that CIB2 represents a novel endogenous and atrial-enriched regulator that protects against atrial remodeling and AF under stress conditions. Therefore, CIB2 may represent a new potential target for treating AF.

Gene Therapy With the N-Terminus of Junctophilin-2 Improves Heart Failure in Mice.

BACKGROUND: Transcriptional remodeling is known to contribute to heart failure (HF). Targeting stress-dependent gene expression mechanisms may represent a clinically relevant gene therapy option. We recently uncovered a salutary mechanism in the heart whereby JP2 (junctophilin-2), an essential component of the excitation-contraction coupling apparatus, is site-specifically cleaved and releases an N-terminal fragment (JP2NT [N-terminal fragment of JP2]) that translocates into the nucleus and functions as a transcriptional repressor of HF-related genes. This study aims to determine whether JP2NT can be leveraged by gene therapy techniques for attenuating HF progression in a preclinical pressure overload model. METHODS: We intraventricularly injected adeno-associated virus (AAV) (2/9) vectors expressing eGFP (enhanced green fluorescent protein), JP2NT, or DNA-binding deficient JP2NT (JP2NTΔbNLS/ARR) into neonatal mice and induced cardiac stress by transaortic constriction (TAC) 9 weeks later. We also treated mice with established moderate HF from TAC stress with either AAV-JP2NT or AAV-eGFP. RNA-sequencing analysis was used to reveal changes in hypertrophic and HF-related gene transcription by JP2NT gene therapy after TAC. Echocardiography, confocal imaging, and histology were performed to evaluate heart function and pathological myocardial remodeling following stress. RESULTS: Mice preinjected with AAV-JP2NT exhibited ameliorated cardiac remodeling following TAC. The JP2NT DNA-binding domain is required for cardioprotection as its deletion within the AAV-JP2NT vector prevented improvement in TAC-induced cardiac dysfunction. Functional and histological data suggest that JP2NT gene therapy after the onset of cardiac dysfunction is effective at slowing the progression of HF. RNA-sequencing analysis further revealed a broad reversal of hypertrophic and HF-related gene transcription by JP2NT overexpression after TAC. CONCLUSIONS: Our prevention- and intervention-based approaches here demonstrated that AAV-mediated delivery of JP2NT into the myocardium can attenuate stress-induced transcriptional remodeling and the development of HF when administered either before or after cardiac stress initiation. Our data indicate that JP2NT gene therapy holds great potential as a novel therapeutic for treating hypertrophy and HF.

I2-Mediated [3 + 3] Annulation for the Construction of Indole-Pyrimidine-Pyrazole-Fused Tetracyclic Heteroarenes.

An I2-mediated annulation of 3-aminopyrazoles with indole-3-carboxaldehydes has been demonstrated for the first time. This tandem strategy allows the facile construction of indole-pyrimidine-pyrazole-fused tetracyclic heteroarenes that are otherwise inaccessible by the existing methods. These fused heterocycles exhibited enhanced antifungal activities against Valsa mali and Botryosphaeria dothidea compared with commercial Xemium fungicide.

Vagococcus fluvialis isolation from the urine of a bladder cancer patient: a case report.

Vagococcus fluvialis infection is rare in humans, and there is limited research on the clinical manifestations and antimicrobial susceptibility testing of Vagococcus fluvialis infection. Here, We isolated Vagococcus fluvialis from the urine samples of bladder cancer patients at Hunan Provincial People's Hospital, and it is the first reported case of Vagococcus fluvialis isolated from the urine. The fully automated microbial identification system and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) identified the bacterium as Vagococcus fluvialis with a confidence level of 99.9%. The VITEK-2Compact fully automated microbial susceptibility analysis system indicated that it was most sensitive to tigecycline, vancomycin, quinupristin/dalfopristin, linezolid, and showed moderate sensitivity to erythromycin, levofloxacin, ciprofloxacin, ampicillin/sulbactam, and tetracycline. Additionally, it exhibited synergy when combined with high-level gentamicin and vancomycin, showing sensitivity. However, it displayed poor activity against penicillin and furanth. According to our knowledge, this is the first study to isolate and identify Vagococcus fluvialis from the urine of bladder cancer patients and the systematically reviewed other reported Vagococcus infections on human, which provide an experimental basis for guiding the rational use of drugs in the clinical treatment and diagnose of Vagococcus fluvialis infection and related pathogenic mechanism research. Meanwhile, we have systematically reviewed other reported.

Diurnal temperature range and cardiopulmonary health in Taiwan: Evaluating impacts, thresholds, and vulnerable groups.

The health impacts of the diurnal temperature range (DTR), which may be affected by climate change, have received little attention. The objectives of this study were (1) to evaluate the association of DTR and cardiopulmonary outcomes, (2) to select the proper thresholds for a DTR warning system, and (3) to identify vulnerable groups. The weather and health records in Taiwan from 2000 to 2019, with a maximum DTR of 12.8 °C, were analyzed using generalized additive models. The health outcomes included cardiovascular (CVD) and respiratory disease (RD) categories and several sub-categories, such as ischemic heart disease, stroke, pneumonia, asthma, and chronic obstructive pulmonary disease. The results showed that the associations of DTR and cardiopulmonary outcomes were as significant as, and sometimes even stronger than, those of the daily maximum temperature and daily minimum apparent temperature in the warm and cold seasons, respectively. The significant association began at DTR of 6 °C, lower than previously reported. The identified DTR warning thresholds were 8.5 and 11 °C for the warm and cold seasons, respectively. DTR is statistically significantly associated with a 5-36% and a 9-20% increase in cardiopulmonary emergency and hospitalized cases in the warm season with a 1 °C increase above 8.5 °C, respectively. In the cold season, DTR is significantly associated with 7-41%, 4-30%, and 36-100% increases in cardiopulmonary emergency, hospitalized, and mortality with a 1 °C increase above 11 °C, respectively. People with hypertension, hyperglycemia, and hyperlipidemia had even higher risks. Vulnerable age and sex groups were identified if they had a lower DTR-health threshold than the general population, which can be integrated into a warning system. In conclusion, DTR may be increased on a local or city scale under climate change; a DTR warning system and vulnerable group identification may be warranted in most countries for health risk reduction.

Effects of 0.4 T, 3.0 T and 9.4 T static magnetic fields on development, behaviour and immune response in zebrafish (Danio rerio).

Magnetic Resonance Imaging (MRI) is widely applied in medical diagnosis due to its excellent non-invasiveness. With the increasing intensity of static magnetic field (SMF), the safety assessment of MRI has been ongoing. In this study, zebrafish larvae were exposed to SMFs of 0.4, 3.0, and 9.4 T for 2 h (h), and we found that there was no significant difference in the number of spontaneous tail swings, heart rate, and body length of zebrafish larvae in the treatment groups. The expression of development-related genes shha, pygo1, mylz3 and runx2b in the three SMF groups was almost not significantly different from the control group. Behavior tests unveiled a notable reduction in both the average speed and duration of high-speed movements in zebrafish larvae across all three SMF groups. In addition, the 0.4 and 3.0 T SMFs increased the migration of neutrophils in caudal fin injury, and the expression of pro-inflammatory cytokines was also increased. To explore the mechanism of SMFs on zebrafish immune function, this study utilized aanat2-/- mutant fish to demonstrate the effect of melatonin (MT) involvement in SMFs on zebrafish immune function. This study provides experimental data for understanding the effects of SMFs on organisms, and also provides a new insight for exploring the relationship between magnetic fields and immune function.

Native architecture and acclimation of photosynthetic membranes in a fast-growing cyanobacterium.

Efficient solar energy conversion is ensured by the organization, physical association, and physiological coordination of various protein complexes in photosynthetic membranes. Here, we visualize the native architecture and interactions of photosynthetic complexes within the thylakoid membranes from a fast-growing cyanobacterium Synechococcus elongatus UTEX 2973 (Syn2973) using high-resolution atomic force microscopy. In the Syn2973 thylakoid membranes, both photosystem I (PSI)-enriched domains and crystalline photosystem II (PSII) dimer arrays were observed, providing favorable membrane environments for photosynthetic electron transport. The high light (HL)-adapted thylakoid membranes accommodated a large amount of PSI complexes, without the incorporation of iron-stress-induced protein A (IsiA) assemblies and formation of IsiA-PSI supercomplexes. In the iron deficiency (Fe-)-treated thylakoid membranes, in contrast, IsiA proteins densely associated with PSI, forming the IsiA-PSI supercomplexes with varying assembly structures. Moreover, type-I NADH dehydrogenase-like complexes (NDH-1) were upregulated under the HL and Fe- conditions and established close association with PSI complexes to facilitate cyclic electron transport. Our study provides insight into the structural heterogeneity and plasticity of the photosynthetic apparatus in the context of their native membranes in Syn2973 under environmental stress. Advanced understanding of the photosynthetic membrane organization and adaptation will provide a framework for uncovering the molecular mechanisms of efficient light harvesting and energy conversion.

Coexistence of Dirac points and nodal chains in photonic metacrystal.

Gapless topological phases, i.e. topological semimetals, come in various forms such as Weyl/Dirac semimetals, nodal line/chain semimetals, and surface-node semimetals. However, the coexistence of two or more topological phases in a single system is still rare. Here, we propose the coexistence of Dirac points and nodal chain degeneracies in a judiciously designed photonic metacrystal. The designed metacrystal exhibits nodal line degeneracies lying in perpendicular planes, which are chained together at the Brillouin zone boundary. Interestingly, the Dirac points, which are protected by nonsymmorphic symmetries, are located right at the intersection points of nodal chains. The nontrivial Z2 topology of the Dirac points is revealed by the surface states. The Dirac points and nodal chains are located in a clean frequency range. Our results provide a platform for studying the connection between different topological phases.

Dirac-Weyl semimetal in photonic metacrystals.

Dirac-Weyl semimetal is a novel type of topological phase that features the coexistence of Dirac and Weyl points in momentum space. In this study, a photonic Dirac-Weyl semimetal is proposed by introducing screw rotation symmetries into a spatial inversion symmetry-lacking system. A realistic metacrystal structure is designed for experimental consideration. The screw rotation symmetries are crucial for the existence of Dirac points, whose Z2 topology is revealed by the (010) surface states. Meanwhile, two pairs of ideal Weyl points at the same frequency are protected by D2d point group symmetries. The Dirac points and Weyl points reside in a clean frequency interval. The proposed photonic Dirac-Weyl semimetal provides a versatile platform for exploring the interaction between Dirac and Weyl semimetals and exploiting possible photonic topological devices.

Fluviispira vulneris sp. nov., isolated from human wound secretions.

Human infections by environmental bacteria is becoming an increasing problem and has become a matter of great concern due to the adverse effects worldwide. In this study, we reported a new environmental pathogen. Isolate GX5518T was a novel Gram-negative, aerobic, non-motile, pleomorphic and red-pigmented bacterium, was isolated from human wound secretions (GuangXi, People's Republic of China). Growth occurred at pH 6.0-8.0 (optimum, pH 7.0) and 10-37 °C (optimum, 28-32 °C) with 0-1.5% (w/v) NaCl in R2A agar. Comparative analysis of the 16S rRNA gene sequences revealed that isolate GX5518T was closely related to Fluviispira sanaruensis JCM 31447T (99.73%) and Fluviispira multicolorata 33A1-SZDPT (98.49%). However, the estimated ANI values of the isolate GX5518T compared to the F. sanaruensis JCM 31447T and F. multicolorata 33A1-SZDPT were 88.67% and 77.35%, respectively. The estimated dDDH, ANI and AAI values between isolate GX5518T and its closely related strains were below the threshold values generally considered for recognizing a new species. The genome size was 3.6 Mbp and the DNA G + C content was 33.1%. The predominant fatty acids (> 5%) in GX5518T cells were iso-C15:0, C16:0, C17:0, C17:1 ω8c and C16:1 ω7c/C16:1 ω6c. The major menaquinone was MK-8 (86.9%). The polar lipids were phosphatidylethanolamine (PE), phosphatidylglycerol (PG) and three unknown lipids (L1-3). The chemical composition was different from that of the F. sanaruensis JCM 31447T. Comparative genomics analysis between isolate GX5518T and its related strains revealed that there were a number of genes involved in resistance to antibiotics and toxic compounds in isolate GX5518T, which were responsible for the copper homeostasis, cobalt-zinc-cadmium resistance, resistance to fluoroquinolones, and zinc resistance. Based on the phenotypic, chemotaxonomic, and genomic analyses, isolate GX5518T (= CGMCC 1.18685T = KCTC 82149T) represents a novel species of the genus Fluviispira, for which the name Fluviispira vulneris sp. nov. is proposed.

Platelet extracellular vesicles are efficient delivery vehicles of doxorubicin, an anti-cancer drug: preparation and in vitro characterization.

Platelet extracellular vesicles (PEVs) are an emerging delivery vehi for anticancer drugs due to their ability to target and remain in the tumor microenvironment. However, there is still a lack of understanding regarding yields, safety, drug loading efficiencies, and efficacy of PEVs. In this study, various methods were compared to generate PEVs from clinical-grade platelets, and their properties were examined as vehicles for doxorubicin (DOX). Sonication and extrusion produced the most PEVs, with means of 496 and 493 PEVs per platelet (PLT), respectively, compared to 145 and 33 by freeze/thaw and incubation, respectively. The PEVs were loaded with DOX through incubation and purified by chromatography. The size and concentration of the PEVs and PEV-DOX were analyzed using dynamic light scattering and nanoparticle tracking analysis. The results showed that the population sizes and concentrations of PEVs and PEV-DOX were in the ranges of 120-150 nm and 1.2-6.2 × 1011 particles/mL for all preparations. The loading of DOX determined using fluorospectrometry was found to be 2.1 × 106, 1.7 × 106, and 0.9 × 106 molecules/EV using freeze/thaw, extrusion, and sonication, respectively. The internalization of PEVs was determined to occur through clathrin-mediated endocytosis. PEV-DOX were more efficiently taken up by MDA-MB-231 breast cancer cells compared to MCF7/ADR breast cancer cells and NIH/3T3 cells. DOX-PEVs showed higher anticancer activity against MDA-MB-231 cells than against MCF7/ADR or NIH/3T3 cells and better than acommercial liposomal DOX formulation. In conclusion, this study demonstrates that PEVs generated by PLTs using extrusion, freeze/thaw, or sonication can efficiently load DOX and kill breast cancer cells, providing a promising strategy for further evaluation in preclinical animal models. The study findings suggest that sonication and extrusion are the most efficient methods to generate PEVs and that PEVs loaded with DOX exhibit significant anticancer activity against MDA-MB-231 breast cancer cells.

What is the context?● Current synthetic drug delivery systems can have limitations and side effects.● Platelet extracellular vesicles (PEVs) are a natural and potentially safer alternative for delivering cancer drugs to tumors.● However, there is still a lack of understanding about how to produce PEVs and how effective they are in delivering drugs.What is new?● We compared different methods for producing PEVs from clinical-grade platelets and found that sonication and extrusion were the most effective methods.● The PEVs were loaded with a cancer drug called doxorubicin (DOX) and tested their ability to kill breast cancer cells.What is the impact?● PEVs loaded with DOX were effective at killing cancer cells, especially MDA-MB-231 breast cancer cells.● This study demonstrates that PEVs are a promising strategy for delivering cancer drugs to tumors and that sonication and extrusion are the most efficient methods for producing PEVs.● The results suggest that further evaluation of PEVs in preclinical animal models is warranted to determine their potential as a cancer drug delivery system.Abbreviations: ADP: adenosine diphosphate; bFGF: basic fibroblast growth factor; BSA: bovine serum albumin; CD41: platelet glycoprotein IIb; CD62P: P-selectin; CFDASE: 5-(and-6)-carboxyfluorescein diacetate: succinimidyl ester; CPLT: cryopreserved platelet; CPZ: chlorpromazine hydrochloride; CTC: circulating tumor cell; DMSO: dimethyl sulfoxide; DDS: drug delivery system; DOX: doxorubicin; EPR: enhanced permeability and retention; EV: extracellular vesicle; FBS: fetal bovine serum; GMP: good manufacturing practice; GF: growth factor; HER2: human epidermal growth factor receptor 2; HGF: hepatocyte growth factor; Lipo-DOX: liposomal doxorubicin; MDR: multi-drug resistance; MMP-2: matrix metalloproteinase-2; MP: microparticle; MSC: mesenchymal stromal cell; NP: nanoparticle; NTA: nanoparticle tracking analysis; PAR-1: protease activated receptor-1; PAS: platelet additive solution; PBS: phosphate-buffered saline; PC: platelet concentrate; PEG: polyethylene glycol; PEV: platelet-derived extracellular vesicle; DOX-PEV: doxorubicin-loaded platelet-derived extracellular vesicle-encapsulated; PFA: paraformaldehyde; PF4: platelet factor 4; P-gp: P-glycoprotein; PLT: platelet; PS: phosphatidylserine; SDS-PAGE: sodium dodecylsulfate polyacrylamide gel electrophoresis; SEM: scanning electron microscopy; TCIPA: tumor cell-induced PLT aggregation; TDDS: targeted drug delivery system; TEG: thromboelastography; TF: tissue factor; TF-EV: extracellular vesicle expressing tissue factor; TME: tumor microenvironment; TNBC: triple-negative breast cancer; TXA2: thromboxane-A2; VEGF: vascular endothelial growth factor; WHO: World Health Organization.

Cytokine receptor gp130 promotes postnatal proliferation of cardiomyocytes required for the normal functional development of the heart.

Mammalian ventricular cardiomyocytes are premature at birth and exhibit substantial phenotypic changes before weaning. Mouse ventricular myocytes undergo cell division several times after birth; however, the regulatory mechanisms and roles of cardiomyocyte division in postnatal heart development remain unclear. Here, we investigated the physiological role of glycoprotein 130 (gp130), the main subunit of multifunctional receptors for the IL-6 family of cytokines, in postnatal cardiomyocyte proliferation. Pharmacological inhibition of gp130 within the first month after birth induced significant systolic dysfunction of the left ventricle in mice. Consistently, mice with postnatal cardiomyocyte-specific gp130 depletion exhibited impaired left ventricular contractility compared with control mice. In these mice, cardiomyocytes exhibited a moderately decreased size and dramatically inhibited proliferation in the left ventricle but not in the right ventricle. Stereological analysis revealed that this change significantly decreased the number of cardiomyocytes in the left ventricle. Furthermore, IL-6 was mainly responsible for promoting ventricular cardiomyocyte proliferation by activating the JAK/STAT3 pathway. Taken together, the IL-6/gp130/JAK/STAT3 axis plays a crucial role in the physiological postnatal proliferation and hypertrophy of left ventricular cardiomyocytes to ensure normal cardiac functional development.NEW & NOTEWORTHY Although cardiomyocytes undergo proliferation in the early postnatal period, the regulatory mechanisms and physiological importance of this process have not been clarified. We found that the pharmacological and genetic depletion of gp130 in preweaning mice resulted in significant impairment of cardiomyocyte proliferation, thinning of the myocardium, and systolic dysfunction of the left but not right ventricle by perturbing JAK/STAT3 signaling. Thus, the IL-6/gp130/JAK/STAT3 axis is crucial for the postnatal functional development of the left ventricle.