Palmdelphin Regulates Nuclear Resilience to Mechanical Stress in the Endothelium

Integrated machine learning and Mendelian randomization reveal PALMD as a prognostic biomarker for nonspecific orbital inflammation

BACKGROUND

Nonspecific Orbital Inflammation (NSOI) remains a perplexing enigma among proliferative inflammatory disorders. Its etiology is idiopathic, characterized by distinctive and polymorphous lymphoid infiltration within the orbital region. Preliminary investigations suggest that PALMD localizes within the cytosol, potentially playing a crucial role in cellular processes, including plasma membrane dynamics and myogenic differentiation. The potential of PALMD as a biomarker for NSOI warrants meticulous exploration.

METHODS

PALMD was identified through the intersection analysis of common DEGs from datasets GSE58331 and GSE105149 from the GEO database, alongside immune-related gene lists from the ImmPort database, using Lasso regression and SVM-RFE analysis. GSEA and GSVA were conducted with gene sets co-expressed with PALMD. To further investigate the correlation between PALMD and immune-related biological processes, the CIBERSORT algorithm and ESTIMATE method were employed to evaluate immune microenvironment characteristics of each sample. The expression levels of PALMD were subsequently validated using GSE105149.

RESULTS

Among the 314 DEGs identified, several showed significant differences. Lasso and SVM-RFE algorithms pinpointed 15 hub genes. Functional analysis of PALMD emphasized its involvement in cell-cell adhesion, leukocyte migration, and leukocyte-mediated immunity. Enrichment analysis revealed that gene sets positively correlated with PALMD were enriched in immune-related pathways. Immune infiltration analysis indicated that resting dendritic cells, resting mast cells, activated NK cells, and plasma cells positively associate with PALMD expression. Conversely, naive B cells, activated dendritic cells, M0 and M1 macrophages, activated mast cells, activated CD4 memory T cells, and naive CD4 T cells showed a negative correlation with PALMD expression. PALMD demonstrated significant diagnostic potential in differentiating NSOI.

CONCLUSIONS

This study identifies PALMD as a potential biomarker linked to NSOI, providing insights into its pathogenesis and offering new avenues for tracking disease progression.

PALMD haploinsufficiency aggravates extracellular matrix remodeling in vascular smooth muscle cells and promotes calcification

Reduced PALMD expression is strongly associated with the development of calcified aortic valve stenosis; however, the role of PALMD in vascular calcification remains unknown. Calcified arteries were collected from mice to detect PALMD expression. Heterozygous Palmd knockout (Palmd+/-) mice were established to explore the role of PALMD in subtotal nephrectomy-induced vascular calcification. RNA sequencing was applied to detect molecular changes in aortas from Palmd+/- mice. Primary Palmd+/- vascular smooth muscle cells (VSMCs) or PALMD-silenced VSMCs by short interfering RNA were used to analyze PALMD function in phenotypic changes and calcification. PALMD haploinsufficiency aggravated subtotal nephrectomy-induced vascular calcification. RNA sequencing analysis showed that loss of PALMD disturbed the synthesis and degradation of the extracellular matrix (ECM) in aortas, including collagens and matrix metalloproteinases (Col6a6, Mmp2, Mmp9, etc.). In vitro experiments revealed that PALMD-deficient VSMCs were more susceptible to high phosphate-induced calcification. Downregulation of SMAD6 expression and increased levels of p-SMAD2 were detected in Palmd+/- VSMCs, suggesting that transforming growth factor-β signaling may be involved in PALMD haploinsufficiency-induced vascular calcification. Our data revealed that PALMD haploinsufficiency causes ECM dysregulation in VSMCs and aggravates vascular calcification. Our findings suggest that reduced PALMD expression is also linked to vascular calcification, and PALMD may be a potential therapeutic target for this disease. NEW & NOTEWORTHY We found that PALMD haploinsufficiency causes extracellular matrix dysregulation, reduced PALMD expression links to vascular calcification, and PALMD mutations may lead to the risk of both calcific aortic valve stenosis and vascular calcification.

Icariin targets p53 to protect against ceramide-induced neuronal senescence: Implication in Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) is a leading cause of dementia. The aging brain is particularly vulnerable to various stressors, including increased levels of ceramide. However, the role of ceramide in neuronal cell senescence and AD progression and whether icariin, a natural flavonoid glucoside, could reverse neuronal senescence remain inadequately understood.

AIM

In this study, we explore the role of ceramide in neuronal senescence and AD, and whether icariin can counteract these effects.

METHODS

We pretreated HT-22 cells with icariin and then induced senescence with ceramide. Various assays were employed to assess cell senescence, such as reactive oxygen species (ROS) production, cell cycle progression, β-galactosidase staining, and expression of senescence-associated proteins. In vivo studies utilized APP/PS1 mice and C57BL/6J mice injected with ceramide to evaluate behavioral changes, histopathological alterations, and senescence-associated protein expression. Transcriptomics, molecular docking, molecular dynamics simulations, and cellular thermal shift assays were employed to verify the interaction between icariin and P53. The specificity of icariin targeting of P53 was further confirmed through rescue experiments utilizing the P53 activator Navtemadlin.

RESULTS

Our data demonstrated that ceramide could induce neuronal senescence and AD-related pathologies, which were reversed by icariin. Moreover, molecular studies revealed that icariin directly targeted P53, and its neuroprotective effects were attenuated by P53 activation, providing evidence for the role of P53 in icariin-mediated neuroprotection.

CONCLUSION

Icariin demonstrates a protective effect against ceramide-induced neuronal senescence by inhibiting the P53 pathway. This identifies a novel mechanism of action for icariin, offering a novel therapeutic approach for AD and other age-related neurodegenerative diseases.

In vivo proximity proteomics uncovers palmdelphin (PALMD) as a Z-disc-associated mitigator of isoproterenol-induced cardiac injury

Z-discs are core ultrastructural organizers of cardiomyocytes that modulate many facets of cardiac pathogenesis. Yet a comprehensive proteomic atlas of Z-disc-associated components remain incomplete. Here, we established an adeno-associated virus (AAV)-delivered, cardiomyocyte-specific, proximity-labeling approach to characterize the Z-disc proteome in vivo. We found palmdelphin (PALMD) as a novel Z-disc-associated protein in both adult murine cardiomyocytes and human pluripotent stem cell-derived cardiomyocytes. Germline and cardiomyocyte-specific Palmd knockout mice were grossly normal at baseline but exhibited compromised cardiac hypertrophy and aggravated cardiac injury upon long-term isoproterenol treatment. By contrast, cardiomyocyte-specific PALMD overexpression was sufficient to mitigate isoproterenol-induced cardiac injury. PALMD ablation perturbed the transverse tubule (T-tubule)-sarcoplasmic reticulum (SR) ultrastructures, which formed the Z-disc-associated junctional membrane complex (JMC) essential for calcium handling and cardiac function. These phenotypes were associated with the reduction of nexilin (NEXN), a crucial Z-disc-associated protein that is essential for both Z-disc and JMC structures and functions. PALMD interacted with NEXN and enhanced its protein stability while the Nexn mRNA level was not affected. AAV-based NEXN addback rescued the exacerbated cardiac injury in isoproterenol-treated PALMD-depleted mice. Together, this study discovered PALMD as a potential target for myocardial protection and highlighted in vivo proximity proteomics as a powerful approach to nominate novel players regulating cardiac pathogenesis.

Regulation of Cellular-Signaling Pathways by Mammalian Proteins Containing Bacterial EPIYA or EPIYA-Like Motifs Predicted to be Phosphorylated

The effector proteins of several pathogenic bacteria contain the Glu-Pro-Ile-Tyr-Ala (EPIYA) motif or other similar motifs. The EPIYA motif is delivered into the host cells by type III and IV secretion systems, through which its tyrosine residue undergoes phosphorylation by host kinases. These motifs atypically interact with a wide range of Src homology 2 (SH2) domain-containing mammalian proteins through tyrosine phosphorylation, which leads to the perturbation of multiple signaling cascades, the spread of infection, and improved bacterial colonization. Interestingly, it has been reported that EPIYA (or EPIYA-like) motifs exist in mammalian proteomes and regulate mammalian cellular-signaling pathways, leading to homeostasis and disease pathophysiology. It is possible that pathogenic bacteria have exploited EPIYA (or EPIYA-like) motifs from mammalian proteins and that the mammalian EPIYA (or EPIYA-like) motifs have evolved to have highly specific interactions with SH2 domain-containing proteins. In this review, we focus on the regulation of mammalian cellular-signaling pathways by mammalian proteins containing these motifs.

Palmdelphin Inhibits Ovarian Cancer Cell Stem Specification via Downregulating Ring Finger Protein 145

This study aimed to investigate the roles of PALMD in ovarian cancer. mRNA expression was detected using RT-qPCR. The aldehyde dehydrogenase (ALDH) activity and biomarkers of ovarian cancer stem cells were determined using flow cytometry. The stemness of ovarian cancer cells was determined using sphere formation assay. Cell viability was determined using CCK-8 assay. The number of colonies was determined using colony formation assay. Cell migration was detected using wound healing assay. Cell invasion was determined using transwell assay. The results showed that PALMD was downregulated in ovarian cancer. Overexpressed PALMD inhibited the proliferative, migrative, and invasive ability of ovarian cancer cells. Moreover, PALMD inhibited the stem-like properties of ovarian cancer cells. Additionally, PALMD downregulated ring finger protein 145 (RNF145) expression, overexpression of which contributed to the aggressiveness of ovarian cancer cells. Taken together, PALMD suppressed ovarian cancer cell stem specification via inhibiting RNF145 expression.

In vivo proximity proteomics uncovers palmdelphin (PALMD) as a Z-line-associated mitigator of isoproterenol-induced cardiac injury

Z-lines are core ultrastructural organizers of cardiomyocytes that modulate many facets of cardiac pathogenesis. Yet a comprehensive proteomic atlas of Z-line-associated components remain incomplete. Here, we established an adeno-associated virus (AAV)-delivered, cardiomyocyte-specific, proximity-labeling approach to characterize the Z-line proteome in vivo. We found palmdelphin (PALMD) as a novel Z-line-associated protein in both adult murine cardiomyocytes and human pluripotent stem cell-derived cardiomyocytes. Germline and cardiomyocyte-specific palmd knockout mice were grossly normal at baseline but exhibited compromised cardiac hypertrophy and aggravated cardiac injury upon long-term isoproterenol treatment. By contrast, cardiomyocyte-specific PALMD overexpression was sufficient to mitigate isoproterenol-induced cardiac injury. PALMD ablation perturbed transverse tubules (T-tubules) and their association with sarcoplasmic reticulum, which formed the Z-line-associated junctional membrane complex (JMC) essential for calcium handling and cardiac function. These phenotypes were associated with disrupted localization of T-tubule markers caveolin-3 (CAV3) and junctophilin-2 (JPH2) and the reduction of nexilin (NEXN) protein, a crucial Z-line-associated protein that is essential for both Z-line and JMC structures and functions. PALMD was found to interact with NEXN and enhance its protein stability while the Nexn mRNA level was not affected. Together, this study discovered PALMD as a potential target for myocardial protection and highlighted in vivo proximity proteomics as a powerful approach to nominate novel players regulating cardiac pathogenesis.

Highlights

In vivo proximity proteomics uncover novel Z-line components that are undetected in in vitro proximity proteomics in cardiomyocytes.PALMD is a novel Z-line-associated protein that is dispensable for baseline cardiomyocyte function in vivo.PALMD mitigates cardiac dysfunction and myocardial injury after repeated isoproterenol insults.PALMD stabilizes NEXN, an essential Z-line-associated regulator of the junctional membrane complex and cardiac systolic function.

Palmdelphin Deficiency Evokes NF-κB Signaling in Valvular Endothelial Cells and Aggravates Aortic Valvular Remodeling

Palmd-deficient mice of advanced age manifest increased aortic valve peak velocity, thickened aortic valve leaflets, and excessive extracellular matrix deposition, which are key features of calcific aortic valve disease. PALMD is predominantly expressed in endothelial cells of aortic valves, and PALMD-silenced valvular endothelial cells are prone to oscillatory shear stress-induced endothelial-to-mesenchymal transition. Mechanistically, PALMD is associated with TNFAIP3 interaction protein 1, a binding protein of TNFAIP3 and IKBKG in NF-κB signaling. Loss of PALMD impairs TNFAIP3-dependent deubiquitinating activity and promotes the ubiquitination of IKBKG and subsequent NF-κB activation. Adeno-associated virus-mediated PALMD overexpression ameliorates aortic valvular remodeling in mice with calcific aortic valve disease, indicating protection.

Oxidative stress and valvular endothelial cells in aortic valve calcification

Calcified aortic valve disease (CAVD) is a common cardiovascular disease in elderly individuals. Although it was previously considered a degenerative disease, it is, in fact, a progressive disease involving multiple mechanisms. Aortic valve endothelial cells, which cover the outermost layer of the aortic valve and are directly exposed to various pathogenic factors, play a significant role in the onset and progression of CAVD. Hemodynamic changes can directly damage the structure and function of valvular endothelial cells (VECs). This leads to inflammatory infiltration and oxidative stress, which promote the progression of CAVD. VECs can regulate the pathological differentiation of valvular interstitial cells (VICs) through NO and thus affect the process of CAVD. Under the influence of pathological factors, VECs can also be transformed into VICs through EndMT, and then the pathological differentiation of VICs eventually leads to the formation of calcification. This review discusses the role of VECs, especially the role of oxidative stress in VECs, in the process of aortic valve calcification.

XPO1 intensifies sorafenib resistance by stabilizing acetylation of NPM1 and enhancing epithelial-mesenchymal transition in hepatocellular carcinoma

Emerging studies have suggested that exportin-1 (XPO1) plays a pivotal role in hepatocellular carcinoma (HCC). However, the underlying mechanism of XPO1 in HCC sorafenib resistance remains enigmatic. The expression of XPO1 in HCC tumor tissues and sorafenib-resistant (SR) cells were analyzed by bioinformatics analysis, immunohistochemistry (IHC) and Western blotting. The interaction mechanism between XPO1 and Nucleophosmin (NPM1) was investigated by immunoprecipitation (IP), Mass-spectrometric (MS) analysis, immunofluorescence colocalization, CRISPR/CAS9 technology and RNA-seq. Analyses were also conducted on KPT-8602 and sorafenib's combined therapeutic effect. Our findings unraveled that the XPO1 overexpression was observed in HCC, and correlated with poorer survival. Knockdown of XPO1 inhibited the migration and proliferation of HCC cells, and also reduced the resistance of HCC cells to sorafenib. Mechanistically, XPO1 interacted with the C-terminus of NPM1 and mediated the acetylation of NPM1 at lysine 54 to maintain sorafenib resistance. XPO1 was bound to Vimentin, resulting in the epithelial-mesenchymal transition (EMT) progression in sorafenib-resistant cells. KPT-8602 in combination with sorafenib suppressed the tumor growth. These results highlighted the therapeutic value of targeting XPO1 in overcoming sorafenib resistance. The combinational treatment of KPT-8602 and sorafenib might be an improved therapeutic option.

The Transcriptomics of the Human Vein Transformation After Arteriovenous Fistula Anastomosis Uncovers Layer-Specific Remodeling and Hallmarks of Maturation Failure

Introduction

The molecular transformation of the human preaccess vein after arteriovenous fistula (AVF) creation is poorly understood. This limits our ability to design efficacious therapies to improve maturation outcomes.

Methods

Bulk RNA sequencing (RNA-seq) followed by paired bioinformatic analyses and validation assays were performed in 76 longitudinal vascular biopsies (veins and AVFs) from 38 patients with stage 5 chronic kidney disease or end-stage kidney disease undergoing surgeries for 2-stage AVF creation (19 matured, 19 failed).

Results

A total of 3637 transcripts were differentially expressed between veins and AVFs independent of maturation outcomes, with 80% upregulated in fistulas. The postoperative transcriptome demonstrated transcriptional activation of basement membrane and interstitial extracellular matrix (ECM) components, including preexisting and novel collagens, proteoglycans, hemostasis factors, and angiogenesis regulators. A postoperative intramural cytokine storm involved >80 chemokines, interleukins, and growth factors. Postoperative changes in ECM expression were differentially distributed in the AVF wall, with proteoglycans and fibrillar collagens predominantly found in the intima and media, respectively. Interestingly, upregulated matrisome genes were enough to make a crude separation of AVFs that failed from those with successful maturation. We identified 102 differentially expressed genes (DEGs) in association with AVF maturation failure, including upregulation of network collagen VIII in medial smooth muscle cells (SMCs) and downregulation of endothelial-predominant transcripts and ECM regulators.

Conclusion

This work delineates the molecular changes that characterize venous remodeling after AVF creation and those relevant to maturation failure. We provide an essential framework to streamline translational models and our search for antistenotic therapies.

Calcific aortic valve disease: mechanisms, prevention and treatment

Calcific aortic valve disease (CAVD) is the most common disorder affecting heart valves and is characterized by thickening, fibrosis and mineralization of the aortic valve leaflets. Analyses of surgically explanted aortic valve leaflets have shown that dystrophic mineralization and osteogenic transition of valve interstitial cells co-occur with neovascularization, microhaemorrhage and abnormal production of extracellular matrix. Age and congenital bicuspid aortic valve morphology are important and unalterable risk factors for CAVD, whereas additional risk is conferred by elevated blood pressure and plasma lipoprotein(a) levels and the presence of obesity and diabetes mellitus, which are modifiable factors. Genetic and molecular studies have identified that the NOTCH, WNT-β-catenin and myocardin signalling pathways are involved in the control and commitment of valvular cells to a fibrocalcific lineage. Complex interactions between valve endothelial and interstitial cells and immune cells promote the remodelling of aortic valve leaflets and the development of CAVD. Although no medical therapy is effective for reducing or preventing the progression of CAVD, studies have started to identify actionable targets.

IL6 gene polymorphism association with calcific aortic valve stenosis and influence on serum levels of interleukin-6

Aortic valve stenosis is the most frequent valve disease in developed countries and its prevalence will increase with population aging. There is still no pharmaceutical treatment nor biomarker to determine the susceptibility to develop aortic stenosis. Therefore, we analyzed the association of polymorphisms in risk loci with calcific aortic stenosis. Patients with aortic valve disease were genotyped for PALMD rs6702619, LPA rs10455872, and IL6 rs1800795 polymorphisms and circulating levels of interleukin-6 (IL-6) were measured. Calcium content of leaflets obtained in valve replacement surgeries was determined by micro-computed tomography. In the genotyping of 578 individuals, we found significant association between PALMD and IL6 polymorphisms and aortic stenosis in patients with tricuspid aortic valve, independently of other potentially confounding variables such as age and dyslipidemia. There was no association of these polymorphisms with valve calcium content, but this value correlated with the mean aortic pressure gradient (r = 0.44; P < 0.001). The CC genotype of IL6 polymorphism was associated with higher levels of serum IL-6 compared to other genotypes (23.5 vs. 10.5 pg/ml, respectively; P = 0.029). Therefore, patients carrying the CC genotype of IL6 rs1800795 polymorphism present higher levels of circulating IL-6 and this could contribute to the severity of the aortic valve stenosis. Our results agree with the identification of IL6 as a locus risk for stenosis and also with the intervention of this cytokine in aortic valve calcification. A more exhaustive follow-up of those patients carrying risk genotypes is therefore recommended.

Antiphospholipid antibodies in patients with calcific aortic valve stenosis

OBJECTIVES

The antiphospholipid syndrome is defined by antiphospholipid antibodies (aPL) together with arterial and/or venous thromboembolism and/or obstetric morbidities. aPL are overrepresented in SLE and acute myocardial infarction, but it is unknown whether aPL are associated with calcific aortic valve stenosis (CAVS) in the general population. The prevalence of aPL and other SLE-associated autoantibodies and their impact on aortic valve transcriptomics were therefore determined.

METHODS

A total of 233 tricuspid CAVS cases (median age 74, 69% male) and an age- and sex-matched control population were included. aPL were measured as anti-cardiolipin and anti-β2Glycoprotein-I of IgG/M/A isotypes. Resilient, thickened and calcified aortic valve (AV) tissue derived from five aPL positive and five matched aPL negative CAVS patients undergoing surgical aortic valve replacement were analysed by microarrays.

RESULTS

The prevalence of positivity for any aPL (IgG/M/A) in patients with CAVS was 6.4% (95% CI 3.6% - 10.4%: n = 233). aPL IgG was significantly more prevalent in CAVS cases vs controls (4.6% vs 0.6%, P = 0.04). AV tissue from aPL IgG/IgM-positive patients was negatively enriched in pathways related to interferon signalling. One hundred differentially expressed genes could predict local AV CAVS progression with supervised machine learning algorithms.

CONCLUSIONS

aPL IgG was more common in CAVS patients compared with matched controls and aPL positivity was associated with altered AV transcriptomics related to local disease progression and interferon pathways. Further studies should aim to establish aPL as a possible risk marker and/or causal factor for CAVS and could offer new precision therapeutic targets.

Nuclear Mechanosensation and Mechanotransduction in Vascular Cells

Vascular cells are constantly subjected to physical forces associated with the rhythmic activities of the heart, which combined with the individual geometry of vessels further imposes oscillatory, turbulent, or laminar shear stresses on vascular cells. These hemodynamic forces play an important role in regulating the transcriptional program and phenotype of endothelial and smooth muscle cells in different regions of the vascular tree. Within the aorta, the lesser curvature of the arch is characterized by disturbed, oscillatory flow. There, endothelial cells become activated, adopting pro-inflammatory and athero-prone phenotypes. This contrasts the descending aorta where flow is laminar and endothelial cells maintain a quiescent and atheroprotective phenotype. While still unclear, the specific mechanisms involved in mechanosensing flow patterns and their molecular mechanotransduction directly impact the nucleus with consequences to transcriptional and epigenetic states. The linker of nucleoskeleton and cytoskeleton (LINC) protein complex transmits both internal and external forces, including shear stress, through the cytoskeleton to the nucleus. These forces can ultimately lead to changes in nuclear integrity, chromatin organization, and gene expression that significantly impact emergence of pathology such as the high incidence of atherosclerosis in progeria. Therefore, there is strong motivation to understand how endothelial nuclei can sense and respond to physical signals and how abnormal responses to mechanical cues can lead to disease. Here, we review the evidence for a critical role of the nucleus as a mechanosensor and the importance of maintaining nuclear integrity in response to continuous biophysical forces, specifically shear stress, for proper vascular function and stability.

Endothelial Mechanosensors for Atheroprone and Atheroprotective Shear Stress Signals

Vascular endothelial cells (ECs), derived from the mesoderm, form a single layer of squamous cells that covers the inner surface of blood vessels. In addition to being regulated by chemical signals from the extracellular matrix (ECM) and blood, ECs are directly confronted to complex hemodynamic environment. These physical inputs are translated into biochemical signals, dictating multiple aspects of cell behaviour and destination, including growth, differentiation, migration, adhesion, death and survival. Mechanosensors are initial responders to changes in mechanical environments, and the overwhelming majority of them are located on the plasma membrane. Physical forces affect plasma membrane fluidity and change of protein complexes on plasma membrane, accompanied by altering intercellular connections, cell-ECM adhesion, deformation of the cytoskeleton, and consequently, transcriptional responses in shaping specific phenotypes. Among the diverse forces exerted on ECs, shear stress (SS), defined as tangential friction force exerted by blood flow, has been extensively studied, from mechanosensing to mechanotransduction, as well as corresponding phenotypes. However, the precise mechanosensors and signalling pathways that determine atheroprone and atheroprotective phenotypes of arteries remain unclear. Moreover, it is worth to mention that some established mechanosensors of atheroprotective SS, endothelial glycocalyx, for example, might be dismantled by atheroprone SS. Therefore, we provide an overview of the current knowledge on mechanosensors in ECs for SS signals. We emphasize how these ECs coordinate or differentially participate in phenotype regulation induced by atheroprone and atheroprotective SS.