C Protein Research Articles

CSTF2 Supports Hypoxia Tolerance in Hepatocellular Carcinoma by Enabling m6A Modification Evasion of PGK1 to Enhance Glycolysis.

Cleavage stimulation factor subunit 2 (CSTF2) is a fundamental factor in the regulation of 3'-end cleavage and alternative polyadenylation of pre-mRNAs. Previous work has identified a tumor-promoting role of CSTF2, suggesting that it may represent a potential therapeutic target. Here, we aimed to elucidate the mechanistic function of CSTF2 in hepatocellular carcinoma (HCC). CSTF2 upregulation was frequent in HCC, and elevated levels of CSTF2 correlated with poor patient prognosis. While CSTF2 inhibition did not suppress HCC growth under non-stress conditions, it supported tolerance and survival of HCC cells under hypoxic conditions. Mechanistically, CSTF2 increased PGK1 protein production to enhance glycolysis, thereby sustaining the energy supply under hypoxic conditions. CSTF2 shortened the 3' untranslated region (3' UTR) of phosphoglycerate kinase 1 (PGK1) pre-mRNA by binding near the proximal polyadenylation site (pPAS). This shortening led to a loss of N6-methyladenosine (m6A) modification sites that are bound by YTH N6-methyladenosine RNA-binding protein F2 (YTHDF2) and increase degradation of PGK1 mRNA. Concurrently, hypoxia increased m6A modification of PGK1 mRNA near the pPAS that was recognized by the YTH N6-methyladenosine RNA-binding protein C1 (YTHDC1), which recruited CSTF2 to enhance the shortening of the PGK1 3'-UTR. A small molecule screen identified masitinib as an inhibitor of CSTF2. Masitinib counteracted PGK1 upregulation by CSTF2 and suppressed the growth of HCC xenograft and patient-derived organoid models. In conclusion, this study revealed a function of CSTF2 in supporting HCC survival under hypoxia conditions through m6A modification evasion and metabolic reprogramming, indicating inhibiting CSTF2 may overcome hypoxia tolerance in HCC.

M6A-methylase METTL3 promotes retinal angiogenesis through modulation of metabolic reprogramming in RPE cells

Retinal neovascularization (RNV) disease is one of the leading causes of blindness, yet the molecular underpinnings of this condition are not well understood. To delve into the critical aspects of cell-mediated angiogenesis, we analyzed our previously published single-cell data. Our analysis revealed that retinal pigment epithelium (RPE) cells serve a crucial promotional function in angiogenesis. RPE cells were regulated by N6-methyladenosine (m6A). Next, we detected several critical m6A methylase in hypoxic ARPE-19 cells and in oxygen-induced retinopathy (OIR) mice, our results revealed a significant decrease in the level of methyltransferase like 3 (METTL3). METTL3 specific inhibitor STM2457 intravitreal injection or METTL3 conditional knockout mice both showed a significantly reduced neovascularization area of retina. Additionally, the angiogenesis-related abilities of human retinal endothelial cells (HRECs) were diminished after co-cultured with ARPE-19 treated with STM2457 or sh-METTL3 in vitro. Furthermore, through the integration of Methylated RNA immunoprecipitation (MeRIP) sequencing and RNA sequencing, we discovered that the metabolic enzyme quinolinate phosphoribosyltransferase (QPRT) was directly modified by METTL3 and recognized by the YTH N6-methyladenosine RNA binding protein C1 (YTHDC1). Moreover, after over-expressing QPRT, the angiogenic abilities of HRECs were improved through the phosphorylated phosphatidylinositol-3-kinase (p-PI3K)/ phosphorylated threonine kinase (p-AKT) pathway. Collectively, our study provided a novel therapeutic target for retinal angiogenesis.

Complement proteins and complement regulatory proteins are associated with age-related macular degeneration stage and treatment response

BackgroundDysregulation of the complement system is involved in development of age-related macular degeneration (AMD). The complement cascade is regulated by membrane bound complement regulatory proteins (Cregs) on mononuclear leukocytes among others. This study aims to investigate systemic complement proteins and Cregs in AMD stages and their association with treatment response in neovascular AMD (nAMD).MethodsIn this clinical prospective study, treatment-naïve patients with nAMD, intermediate AMD (iAMD) and healthy controls were recruited and systemic complement proteins C3, C3a and C5a were investigated with electrochemiluminescence immunoassays, and Creg expression (CD35, CD46 and CD59) on T cells (CD4 + and CD8+) and monocytes (classical, intermediate and non-classical) investigated with flow cytometry. Treatment response in nAMD patients was evaluated after loading dose and after one year, and categorized as good, partial or poor. Complement proteins and Creg expression levels were compared between healthy controls, iAMD and nAMD, as well as between good, partial and poor nAMD treatment response groups. Polymorphisms in the CFH and ARMS2 genes were analyzed and compared to complement proteins and Creg expression levels in nAMD patients.ResultsOne hundred patients with nAMD, 34 patients with iAMD and 61 healthy controls were included. 94 nAMD patients completed the 1-year follow-up. Distribution of treatment response in nAMD was 61 (65%) good, 26 (28%) partial, and 7 (7%) poor responders. The distribution of 1-year treatment response was 50 (53%) good, 33 (36%) partial, and 11 (11%) poor responders. The concentrations of systemic C3, C3a, and the C3a/C3-ratio were significantly increased in patients with nAMD compared to healthy controls (P < 0.001, P = 0.002, and P = 0.035, respectively). Systemic C3 was also increased in iAMD compared to healthy controls (P = 0.031). The proportion of CD46 + CD4 + T cells and CD59 + intermediate monocytes were significantly decreased in patients with nAMD compared to healthy controls (P = 0.018 and P = 0.042, respectively). The post-loading dose partial treatment response group had significantly lower concentrations of C3a and C5a compared to the good response group (P = 0.005 and P = 0.042, respectively). The proportion of CD35 + monocytes was significantly lower in the 1-year partial response group compared to the 1-year good response group (P = 0.039). High-risk CFH genotypes in nAMD patients was associated with increased C3a, C3a/C3-ratio, and expression levels of CD35 + CD8 + T cells and CD46 + classical monocytes, while expression level of CD46 + non-classical monocytes was decreased.ConclusionElevated concentrations of systemic complement proteins were found in patients with iAMD and nAMD. Decreased Creg expression levels were found in patients with nAMD. Partially responding nAMD patients had a dysregulated complement system and Cregs compared to good responders.

A Novel Mutation of FOXC1 (P136L) in an Axenfeld–Rieger Syndrome Patient With a Systematized Delusion of Jealousy: A Case Report and Literature Review

ABSTRACTBackgroundThe main features of Axenfeld–Rieger Syndrome (ARS) are ocular, auditory, neurological, and morphological brain abnormalities. Mutations in forkhead box protein C1 (FOXC1) are among the responsible genes causing ARS, but neuropsychiatric features have rarely been reported. The case of an ARS patient (a 77‐year‐old man) with delusions of jealousy and impairment of working memory, in addition to the main clinical features, glaucoma and leukoencephalopathy, is presented.MethodsThe mutation in the patient's genome was found with whole exome sequencing and in silico analysis using PolyPhen‐2 and SIFT. Furthermore, AlphaFold2 and PyMOL were used to predict the protein structure based on the mutation.ResultsA novel mutation at the forkhead domain of FOXC1 gene (c.408C&gt;A, p.Phe136Leu) was found and confirmed in the patient's family, and it was predicted to cause protein damage; the SIFT score was 0, meaning deleterious, and the PolyPhen2 result also indicated damaging (score: 0.997). The predicted protein structure based on the novel mutation was different from that of the native structure. In the literature review, 6 of 95 (6.3%) cases showed neuropsychiatric features. Of them, 5 of 6 (83.3%) mutations were located in the forkhead domain.ConclusionA novel mutation was found in the FOXC1 gene (c.408C&gt;A, p.Phe136Leu), which possibly induces delusions of jealousy and impairment of working memory, as well as features of ARS, by changing the protein structure. Mutations in that domain of the FOXC1 gene may be important not only for ocular abnormalities but also for brain function.

OsPP2C49, a Negative Regulatory Factor in the Abscisic Acid Signaling Pathway, Positively Regulates Grain Yield in Rice

Clade A type 2C protein phosphatases (PP2Cs) are crucial components of the abscisic acid (ABA) signaling pathway. Research on clade A PP2Cs has focused more on their roles related to ABA signaling and stress responses than on the molecular mechanisms mediating their effects on plant growth and grain yield. Rice (Oryza sativa L.) is an important food crop worldwide. We previously determined that OsPP2C49, which encodes a rice clade A PP2C family member, negatively controls rice responses to drought, salt, and high-temperature stresses. In this study, we investigated the regulatory effects of OsPP2C49 on ABA responses and rice grain yield. By analyzing potential interactions with core ABA components, including pyrabactin resistance 1 (PYR1)/PYR1-like (PYL)/regulatory component of the ABA receptor (RCAR) and stress-activated protein kinases (SAPKs), we confirmed that OsPP2C49 is involved in the ABA signaling pathway. OsPP2C49 overexpression led to decreased ABA sensitivity and increased rice grain yield; the opposite phenotypes were observed in the ospp2c49 knockout mutants. Therefore, OsPP2C49 negatively regulates ABA responses, but positively modulates rice grain yield. Furthermore, we found that OsPP2C49 can interact with and dephosphorylate five OsSAPKs in vitro. Unlike OsPP2C49, these OsSAPKs positively modulate ABA responsiveness, but negatively affect rice yield. These findings indicate that OsPP2C49 may partially regulate ABA responses and rice grain production by dephosphorylating OsSAPKs. This study preliminarily explored the molecular basis of the regulatory effects of OsPP2C49 on rice plant growth and grain yield.

A Positive Role for CaMEKK17 in Response to Drought Stress, Modulated by Clade A PP2Cs.

The abscisic acid (ABA) signaling pathway is essential for plant response to abiotic stresses and can be modulated positively or negatively by MAPKKK proteins. This study focuses on the functional characterization of CaMEKK17, a MAPKKK previously recognized for its rapid induction under drought stress. Functional analyses demonstrated that CaMEKK17 is an active serine/threonine kinase with a conserved catalytic domain that is crucial for its kinase activity. CaMEKK17 silencing in pepper plants resulted in reduced drought tolerance, characterized by increased transpirational water loss and impaired ABA-mediated stomatal closure. Conversely, CaMEKK17 overexpression in Arabidopsis increased kinase activity, enhancing ABA sensitivity and drought tolerance. Further investigation revealed that CaMEKK17 interacts with pepper group A type 2C protein phosphatases (PP2Cs), particularly CaAITP1 and CaAIPP1, which inhibit its kinase activity. Protein-protein interactions mediated inhibition by CaAITP1, whereas CaAIPP1 relied on its phosphatase activity. Double gene silencing of CaMEKK17 and CaAITP1 demonstrated that CaMEKK17 functions downstream of CaAITP1 in ABA-mediated drought tolerance. Taken together, our findings suggest that CaMEKK17 positively modulates drought tolerance in pepper plants but may be inhibited by PP2Cs.

UBE3C restricts EV-A71 replication by ubiquitination-dependent degradation of 2C.

The highly conserved 2C protein of EV-A71 is a multifunctional protein and plays a key role in the replication cycle. In this study, we demonstrated for the first time that UBE3C promoted the degradation of 2C K268 via K33/K48-linked ubiquitination, thereby inhibiting viral proliferation. Our findings advance the knowledge related to the roles of 2C in EV-A71 virulence and the ubiquitination pathway in the host restriction of EV-A71 infection.

Stearoyl coenzyme A desaturase 1 (SCD1) regulates foot-and-mouth disease virus replication by modulating host cell lipid metabolism and viral protein 2C-mediated replication complex formation.

Many positive-stranded RNA viruses, including foot-and-mouth disease virus (FMDV), alter host membranes and lipid metabolism to create a suitable microenvironment for their survival and replication within host cells. In FMDV-infected cells, the endoplasmic reticulum membrane is remodeled, forming vesicular structures that rely heavily on increased free fatty acids, thereby linking lipid metabolism to the FMDV replication complex. Nonstructural FMDV protein 2C is crucial for this complex, while host cell enzyme stearoyl coenzyme A desaturase 1 (SCD1) is vital for lipid metabolism. We found that FMDV infection alters SCD1 expression in host cells. Inhibiting SCD1 expression or its enzymatic activity markedly decreases FMDV replication, while supplementing oleic acid, a catalytic product of SCD1, regulates FMDV replication. Additionally, SCD1 forms part of the FMDV replication complex and helps recruit 2C to a detergent-resistant membrane. Our study provides insights into the pathogenesis of FMDV and a potential novel drug target against the virus.

C3a Mediates Endothelial Barrier Disruption in Brain-Derived, but Not Retinal, Human Endothelial Cells.

Neuromyelitis optica spectrum disorder (NMOSD) is associated with pathological aquaporin-4 immunoglobulin G (AQP4-IgG), which cause brain damage. However, the impact of AQP4-IgG on retinal tissue remains unclear. Additionally, dysregulated complement anaphylatoxins C3a and C5a, known to modulate the endothelial barrier, are implicated in NMOSD. This study evaluates the susceptibility of human brain microvascular endothelial cells (HBMEC) and human retinal endothelial cells (HREC) to C3a- and C5a-mediated stress using real-time cell barrier analysis, immunocytochemical staining, qPCR and IgG transmigration assays. The findings reveal that C3a induced a concentration-dependent paracellular barrier breakdown and increased transcellular permeability in HBMEC, while HREC maintained barrier integrity under the same conditions. C5a attenuated C3a-induced disruption in HBMEC, indicating a protective role. Anaphylatoxin treatment elevated transcript levels of complement component C3 and increased C5 gene and protein expression in HREC, with no changes observed in HBMEC. In HBMEC, C5a treatment led to a transient upregulation of C3a receptor (C3AR) mRNA and an early decrease in C5a receptor 1 (C5AR1) protein detection. Conversely, HREC exhibited a late increase in C5aR1 protein levels. These results indicate that the retinal endothelial barrier is more stable under anaphylatoxin-induced stress compared to the brain, potentially offering better protection against paracellular AQP4-IgG transport.

Nanoparticle-Binding Immunoglobulins Predict Variable Complement Responses in Healthy and Diseased Cohorts.

Systemic administration of nanomedicines results in the activation of the complement cascade, promoting phagocytic uptake and triggering proinflammatory responses. Identifying the biomarkers that can predict the "risk" of abnormally high complement responders can improve the safety and efficacy of nanomedicines. Polyethylene glycol (PEG) and dextran are two types of clinically approved polymer coatings that trigger complement activation. We performed a multifaceted analysis of the factors affecting the complement activation by PEGylated liposomal doxorubicin (PLD) and dextran-coated superparamagnetic iron oxide nanoworms (SPIO NWs) in plasma from patients with different inflammatory disease conditions and healthy donors. The complement activation (measured as deposition of the complement protein C3) varied greatly, with 29-fold and 26-fold differences for PLD and SPIO NWs, respectively. Chronic inflammation, acute infection, use of steroids, and sex had minor effects on the variable complement activation, whereas age inversely correlated with the complement activation. C-reactive protein level was not predictive of high (top 20th percentile) complement responses. Plasma concentrations of the main complement factors, as well as total IgG and IgM, showed no correlation with the activation by either nanoparticle. On the other hand, plasma concentrations of anti-PEG IgG and IgM showed a strong positive correlation with the activation by PLD. Particularly, titers of anti-PEG IgM showed the best predictive value for the "risk" of high complement activation by PLD. Titers of antidextran IgG and IgM showed a lower correlation with the activation by SPIO NWs and poor predictive value of the top 20% complement responses. Nanoparticle-bound immunoglobulins showed the best correlation with complement activation and a strong predictive value, supporting the critical role of immunoglobulins in inciting complement. The opsonization of PLD with C3 in plasma with high anti-PEG antibodies was predominantly via the alternative pathway. Characterizing the nature of nanoparticle-binding antibodies has important implications in mitigating and stratifying nanomedicine safety.

Impact of Genetic Testing on the Diagnosis, Management, and Prognosis of Hypertrophic Cardiomyopathy: A Systematic Review.

Hypertrophic cardiomyopathy (HCM) is a hereditary cardiovascular condition marked by heart muscle thickening, fibrosis, and myocardial disorders. It is often inherited in an autosomal dominant pattern. Symptoms include dyspnea, fatigue, palpitations, dizziness, syncope, and an increased risk of sudden cardiac death (SCD). Genetic studies have identified many asymptomatic carriers, indicating a higher prevalence of HCM. Advances in genetic testing (GT) and novel therapies, such as cardiac myosin inhibitors, have significantly impacted the diagnosis and management of HCM. This integrative review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and aimed to synthesize information regarding the impact of GT on the diagnosis and management of HCM patients. An electronic search was conducted on May 17, 2024, across PubMed, Embase, Scopus, Web of Science, and Cochrane databases, covering January 2020 to May 2024. Inclusion criteria were studies involving adult HCM patients who underwent GT and follow-up. Exclusion criteria included non-human studies, pediatric cases, non-HCM-related GT, non-peer-reviewed articles, systematic reviews, conference abstracts, and editorials. From 1,155 articles identified, 42 met the inclusion criteria after applying filters and removing duplicates. GT identified pathogenic variants in a significant proportion of HCM patients, enhancing diagnostic accuracy and management. Key mutations were found in myosin binding protein C3 and myosin heavy chain 7 genes. GT facilitated personalized management strategies, including risk stratification for SCD and family screening. Patients with identified mutations often required closer monitoring and tailored treatments. GT has revolutionized the diagnosis and management of HCM. The integration of genetic data has improved risk stratification, facilitated early intervention, and enhanced patient outcomes. Despite these advances, challenges remain in identifying genetic variants in some patients, emphasizing the need for continuous improvement in genetic panels and diagnostic methods. This review highlights the significant role of GT in optimizing HCM care through precise risk assessment and tailored treatment strategies.

CSF complement proteins are elevated in prodromal to moderate Alzheimer's disease patients and are not altered by the anti-tau antibody semorinemab.

Growing evidence suggests a role for neuroinflammation in Alzheimer's disease (AD). We investigated complement pathway activity in AD patient cerebrospinal fluid (CSF) and evaluated its modulation by the anti-tau antibody semorinemab. Immunoassays were applied to measure CSF complement proteins C4, factor B (FB), C3 and their cleavage fragments C4a, C3a, and factor Bb (Bb) in AD patients and a separate cognitively unimpaired (CU) cohort. All measured CSF complement proteins were increased in AD versus CU subjects, with C4a displaying the most robust increase. Finally, semorinemab did not have a significant pharmacodynamic effect on CSF complement proteins. Elevated levels of CSF C4a, C4, C3a, C3, Bb, and FB are consistent with complement activation in AD brains. Despite showing a reduction in CSF soluble tau species, semorinemab did not impact complement protein levels or activity. Further studies are needed to determine the value of complement proteins as neuroinflammation biomarkers in AD. Cerebrospinal fluid (CSF) complement proteins C4a, C3a, Bb, C4, C3, and factor B levels were increased in Alzheimer's disease (AD) patients compared to a separate cognitively unimpaired (CU) cohort. Baseline CSF complement protein levels were correlated with neuro-axonal degeneration and glial activation biomarkers in AD patients. The investigational anti-tau antibody semorinemab did not impact CSF complement protein levels or activity relative to the placebo arm.

7970 C3 and C4 Levels Decrease Post-prandial in Adolescents with type 1 Diabetes

Abstract Disclosure: C.P. Damilano: None. C. Yu: None. D. Zhou: None. R.P. Hoffman: None. Introduction: Cardiovascular disease will be the primary cause of future death for adolescents with type 1 diabetes (T1D) and its origins are likely to occur in this age group. Adolescents with T1D have increased systemic inflammation which is likely to play a significant role in the pathogenesis of cardiovascular disease. The complement system, in particular, components C3 and C4 are part of the innate immune system that regulates inflammation. Increased C3 and C4 levels are associated with increased cardiometabolic risk. Objective: Most studies of inflammation are done while fasting but TNFα and IL6 increase postprandially in adolescent T1D following both high and low glycemic index (GI) meals. The goal of this study was to determine whether there are similar post-prandial changes in C3 and C4 levels. Methodology: Twelve, non-obese children and adolescents, 10-18 years old, with T1D were recruited from the Diabetes Clinic of Nationwide Children's Hospital. A randomized cross-over design for their two subsequent visits was used. After an overnight fast baseline blood samples were taken to measure plasma glucose, C3, total C4 protein, and total C4. Rapid acting insulin was given to cover meal carbohydrate without glucose correction, and blood samples were repeated (30, 60, 90, and 120 minutes) to measure glucose and C3 and C4 levels. Visits 1 and 2 were identical except for GI of the given meal. Visits were rescheduled if the fasting glucose was greater than 200 mg/dl. Repeated measures ANOVA and Spearman’s correlation were used. Results: Glucose response was significantly greater following high GI meal (Δglucose: high 52±12 vs low 6±5 mg/dl, mean±SE, p&amp;lt;0.001). For C3 levels, there was a significant post-prandial decrease (time effect p=0.049), but no meal effect or meal x time interaction. No specific time differences were found. C4 levels were also suppressed postprandially (p&amp;lt;0.001) and there was again no meal effect or meal by time interaction. Post hoc analysis found that C4 levels were lower at 60 min than at 0 min (p=0.007), 90 min (p=0.002) or 120 min (p&amp;lt;0.001). Conclusions: C3 and C4 levels decrease post-prandially in adolescents with T1D in contrast to increases in TNFα and IL6. Future research is clearly needed to clarify the postprandial interactions between the complement and inflammatory systems and potential pathogenic role in cardiovascular disease. Presentation: 6/3/2024

High expression of CD3+T-lymphocytes in cerebrospinal fluid increases the risk of critical cerebral hemorrhage with systemic inflammatory response syndrome (SIRS) after surgery

ObjectiveTo assess the frequency of lymphocyte subsets and other laboratory indicators in paired cerebrospinal fluid (CSF) and peripheral blood (PB) samples from critically ill patients with intracerebral hemorrhage (ICH) who developed systemic inflammatory response syndrome (SIRS) following surgery. IntroductionNeuroinflammation and systemic inflammatory responses significantly contribute to secondary brain injury following ICH. Post-surgery SIRS is known to worsen clinical outcomes in ICH patients; however, the immune response in the CSF and PB has not been fully characterized. Understanding immunological changes in ICH patients with SIRS could lead to improved clinical management and prognostic outcomes. MethodsThis study involved a retrospective analysis of data from patients with ICH who underwent surgery in the Neurological Intensive Care Unit (NICU) of Baoding No. 1 Hospital, Hebei Province, China, between January and July 2022. Patients were divided into SIRS and non-SIRS groups based on the clinical criteria. Demographic, clinical, and laboratory data, including lymphocyte subsets in CSF and PB, were collected and analyzed. This study compared lymphocyte subsets and other inflammatory markers between the SIRS and non-SIRS groups. ResultsPatients with SIRS demonstrated higher systolic blood pressure (SBP) at admission, worse 90-day prognoses, elevated inflammatory markers, increased levels of complement proteins C3 and C4, and lower levels of immunoglobulin G (IgG) compared to patients without SIRS. Between 3–6 days post-surgery, SIRS patients showed higher percentages of CD3+T cells, CD4+T cells, and CD4+/CD8+ ratios in the CSF than non-SIRS patients. CD3+T cell percentages in the CSF were consistently higher than those in the PB and were independent of PB levels. In contrast, CD3-CD16+CD56+ natural killer (NK) cell percentages were lower in patients with SIRS. No significant differences in PB lymphocyte subsets were found between the two groups. A high CSF CD3+T cell percentage (≥85.68 %) was identified as the strongest predictor of critical ICH with SIRS after surgery, with an appropriate use criterion (AUC) of 0.7742, sensitivity of 77.42 %, specificity of 76.19 %, and 95 % CI of 0.6655–0.8829 (P < 0.0001). ConclusionElevated levels of CD3+T lymphocytes in CSF are strongly associated with an increased risk of severe cerebral hemorrhage and SIRS following surgery. These findings suggest that monitoring CSF immune markers, particularly CD3+T lymphocytes, could serve as valuable predictors for the development of SIRS in critically ill ICH patients and inform post-surgical treatment strategies.

Evaluation of galectin-3 and titin in cats with a sarcomeric gene mutation associated with echocardiography

Background and Aim: Cardiac biomarkers, such as serum galectin-3 (Gal-3) and titin levels, may be related to cats with sarcomeric gene mutations. This study evaluated cardiac biomarkers and echocardiographic parameters in cats with or without myosin-binding protein C3 (MYBPC3) gene mutations. Materials and Methods: Forty-two healthy cats without cardiac symptoms, including Bengal, Maine Coon, Scottish fold, and Ragdoll cats, were enrolled in this study. Cats were categorized into three groups: Homozygous wild type (n = 17), homozygous MYBPC3 gene mutation (n = 14), and heterozygous MYBPC3 gene mutation (n = 11). All recruited cats underwent echocardiography, and blood samples were collected for DNA extraction. DNA sequencing for MYBPC3 gene mutations at A31P and A74T loci was first examined by Sanger sequencing. The biomarkers of cardiac fibrosis (Gal-3) and myocardial stiffness (titin) were measured by enzyme-linked immunosorbent assay. Results: Gal-3 levels &gt;250 pg/mL were associated with echocardiographic parameters. However, Gal-3 levels were not significantly different between cats with MYBPC3 gene mutations and those in the wild-type group. Titin was associated with the left ventricular (LV) thickness and systolic function (r = 0.405, p = 0.013). Qualitative measurement of titin antibodies showed that the highest percentage of these antibodies was found in homozygous wild-type cats. No correlation was found between titin levels and MYBPC3 gene mutations. Weight was positively associated with interventricular septum (r = 0.312, p = 0.056) and LV wall thickness (LVPW) (r = 0.219, p = 0.187). However, they were not associated with Gal-3 levels. Conclusion: LVPW was correlated with weight in cats with sarcomeric gene mutations. Serum titin may be an underlying factor for cardiac hypertrophy in cats. Keywords: cardiac biomarker, cat, hypertrophic cardiomyopathy, myosin-binding protein C3.

Urinary Complement C3 and Vitamin D-Binding Protein Predict Adverse Outcomes in Patients with Acute Kidney Injury after Cardiac Surgery

Introduction: Acute kidney injury (AKI) is associated with adverse outcomes, including death and dialysis. The goal of this study was to identify prognostic biomarkers of AKI that could be used across multiple phenotypes of AKI and across different species. Methods: Liquid chromatography/tandem mass spectrometry analysis of urine samples from three species (human, rat, and mouse) and four etiologies of AKI identified five potential biomarkers, of which two were validated, complement C3 and vitamin D-binding protein, in a cohort of 157 patients that developed AKI following cardiothoracic surgery. We studied the relationship between the biomarker’s concentration in the urine and the development of a composite primary endpoint (stage 3 AKI within 10 days or death within 30 days). Results: Of the 153 patients who developed AKI following cardiovascular surgery, 17 met the combined primary outcome. The median concentration of urine complement C3 adjusted to urine creatinine had the best predictive value and was significantly higher in the primary outcome group than in the controls. Similarly, the median concentration of vitamin D-binding protein was higher in the primary outcome group. Conclusions: The studies provide proof in principle that cross-species discovery analyses could be a valuable tool for identifying novel prognostic biomarkers in AKI. Urine complement C3 and vitamin D-binding protein could be promising early predictors of adverse outcomes in patients who develop AKI after cardiac surgery.

Accurate Visualization of C4d Complement Fragment in Immunohistochemistry by C-Terminal Linear Neoepitope-Specific Antibodies

C4d is the end degradation product of activated complement component C4b that appears during the early steps of the classical and lectin complement pathways. Within the primary sequence of C4d, there is a reactive thioester group that binds covalently to nearby surfaces, thus labeling the locations of complement activation. This feature makes C4d a target for immunohistochemical staining aimed to aid the diagnosis of, among others, the antibody-mediated rejection of transplanted organs, membranous glomerulonephritis, bullous pemphigoid, or inflammatory myopathies. However, the credibility of C4d immunostaining is debatable, as a high background in surrounding tissues and body fluids and diffused patterns of deposits in target structures are experienced with some of the available anti-C4d antibodies. Herein, we present an improved version of a rabbit anti-C4d antibody, originally raised against the C-terminal linear neoepitope of this complement fragment. Minor cross-reactivity with C4b and native C4 proteins, measured by ELISAs, as well as relatively low concentrations necessary for obtaining a specific signal in immunohistochemical analyses of formalin-fixed paraffin-embedded material, makes the improved antibody superior to commercially available rabbit monoclonal anti-C4d antibody SP91 dedicated to ex vivo diagnostics, as demonstrated by the staining of a panel of kidney transplant biopsies.

Transcription factor SlSTOP1 regulates Small Auxin-Up RNA Genes for tomato root elongation under aluminum stress.

Aluminum (Al) stress, a prevalent constraint in acidic soils, inhibits plant growth by inhibiting root elongation through restricted cell expansion. The molecular mechanisms of Al-induced root inhibition, however, are not fully understood. This study aimed to elucidate the role of Small Auxin-up RNAs (SlSAURs), which function downstream of the key Al stress-responsive transcription factor SENSITIVE TO PROTON RHIZOTOXICITY 1 (SlSTOP1) and its enhancer STOP1-INTERACTING ZINC-FINGER PROTEIN 1 (SlSZP1), in modulating root elongation under Al stress in tomato (Solanum lycopersicum). Our findings demonstrated that tomato lines with knocked out SlSAURs exhibited shorter root lengths when subjected to Al stress. Further investigation into the underlying mechanisms revealed that SlSAURs interact with Type 2C Protein Phosphatases (SlPP2Cs), specifically D-clade Type 2C Protein Phosphatases (SlPP2C.Ds). This interaction was pivotal as it suppresses the phosphatase activity, leading to the degradation of SlPP2C.D's inhibitory effect on plasma membrane H+-ATPase. Consequently, this promoted cell expansion and root elongation under Al stress. These findings increase our understanding of the molecular mechanisms by which Al ions modulate root elongation. The discovery of the SlSAUR-SlPP2C.D interaction and its impact on H+-ATPase activity also provides a perspective on the adaptive strategies employed by plants to cope with Al toxicity, which may lead to the development of tomato cultivars with enhanced Al stress tolerance, thereby improving crop productivity in acidic soils.

The C5 protein of euphorbia leaf curl virus is a virulence factor and gene silencing suppressor

The genome of a monopartite begomovirus, or the DNA-A component of a bipartite begomovirus, typically encodes six proteins: two on the viral strand (AV1/V1 and AV2/V2) and four on the complementary strand (AC1/C1, AC2/C2, AC3/C3, AC4/C4). Recent studies, however, have identified additional begomoviral proteins with various functions. This paper reports that euphorbia leaf curl virus (EuLCV), a monopartite begomovirus, encodes a seventh protein, C5. Promoter activity of the upstream fragment of the EuLCV C5 gene was shown using a GUS expression vector. EuLCV C5 also enhanced the pathogenicity and accumulation of potato virus X (PVX) in Nicotiana benthamiana. Localization studies revealed that EuLCV C5 localizes to the cytoplasm and nucleus, forming granular structures on the cell membrane. Additionally, C5 acts as a post-transcriptional gene silencing (PTGS) suppressor. A C5 deletion mutant of EuLCV (EuLCV-ΔC5) exhibited reduced pathogenicity and viral accumulation compared to wild-type EuLCV in N. benthamiana.

The ubiquitin E3 ligase RZFP1 affects drought tolerance in poplar by mediating the degradation of the protein phosphatase PP2C-9.

Abscisic acid signaling has been implicated in plant responses to water deficit-induced osmotic stress. However, the underlying molecular mechanism remains unelucidated. This study identified the RING-type E3 ubiquitin ligase RING ZINC FINGER PROTEIN1 (PtrRZFP1) in poplar (Populus trichocarpa), a woody model plant. PtrRZFP1 encodes a ubiquitin E3 ligase that participates in protein ubiquitination. PtrRZFP1 mainly functions in the nucleus and endoplasmic reticulum and is activated by drought and abscisic acid. PtrRZFP1-overexpressing transgenic poplars (35S:PtrRZFP1) showed greater tolerance to drought, whereas PtrRZFP1-knockdown lines (KD-PtrRZFP1) showed greater sensitivity to drought. Under treatment with polyethylene glycol and abscisic acid, PtrRZFP1 promoted the production of NO and H2O2 in stomatal guard cells, ultimately enhancing stomatal closure and improving drought tolerance. Additionally, PtrRZFP1 physically interacted with the clade A Protein Phosphatase 2C protein PtrPP2C-9, a core regulator of abscisic acid signaling, and mediated its ubiquitination and eventual degradation through the ubiquitination-26S proteasome system, indicating that PtrRZFP1 positively regulates the abscisic acid signaling pathway. Furthermore, the PtrPP2C-9-overexpression line was insensitive to abscisic acid and more sensitive to drought than the wild-type plants, whereas the opposite phenotype was observed in 35S:PtrRZFP1 plants. In general, PtrRZFP1 negatively regulates the stability of PtrPP2C-9 to mediate poplar drought tolerance. The results of this study provide a theoretical framework for the targeted breeding of drought-tolerant traits in perennial woody plants.