Anti-apoptotic Function Research Articles

Sigma 1 Receptor and Its Pivotal Role in Neurological Disorders.

Sigma 1 receptor (S1R) is a multifunctional, ligand-activated protein located in the membranes of the endoplasmic reticulum (ER). It mediates a variety of neurological disorders, including epilepsy, amyotrophic lateral sclerosis, Alzheimer's disease, Huntington's disease. The wide neuroprotective effects of S1R agonists are achieved by a variety of pro-survival and antiapoptotic S1R-mediated signaling functions. Nonetheless, relatively little is known about the specific molecular mechanisms underlying S1R activity. Many studies on S1R protein have highlighted the importance of maintaining normal cellular homeostasis through its control of calcium and lipid exchange between the ER and mitochondria, ER-stress response, and many other mechanisms. In this review, we will discuss S1R different cellular localization and explain S1R-associated biological activity, such as its localization in the ER-plasma membrane and Mitochondrion-Associated ER Membrane interfaces. While outlining the cellular mechanisms and important binding partners involved in these processes, we also explained how the dysregulation of these pathways contributes to neurodegenerative disorders.

Exosomes of different cellular origins: prospects and challenges in the treatment of acute lung injury after burns.

Acute lung injury (ALI) is a critical clinical disease caused by direct factors (inhalation injury, gastroesophageal reflux, etc.) or indirect factors (including infection, sepsis, burn, shock, trauma, acute pancreatitis, fat embolism, drug overdose, etc.). ALI is characterized mainly by diffuse interstitial and alveolar edema caused by an uncontrolled inflammatory response and damage to the alveoli-capillary barrier and has very high morbidity and mortality rates. Currently, there is no effective treatment strategy other than mechanical ventilation, fluid management or other supportive treatments. Exosomes are nanovesicle-like vesicles with double-membrane structures detached from the cell membrane or secreted by cells. These vesicles can be used as drug carriers because of their unique biological properties, such as anti-inflammatory, anti-apoptotic, pro-cell growth and immunomodulatory functions, and have been applied in the treatment of ALI in recent years. In this study, the mechanism and pathophysiological characteristics of ALI were first systematically described. The different cellular sources and characteristics of exosomes are summarized, and their functions and value as drug carriers in the treatment of ALI are discussed, as are the challenges that may be faced in the treatment of ALI with exosomes.

MARCH8 Restricts RSV Replication by Promoting Cellular Apoptosis Through Ubiquitin-Mediated Proteolysis of Viral SH Protein.

Numerous host factors function as intrinsic antiviral effectors to attenuate viral replication. MARCH8 is an E3 ubiquitin ligase that has been identified as a host restriction factor that inhibits the replication of various viruses. This study elucidated the mechanism by which MARCH8 restricts respiratory syncytial virus (RSV) replication through selective degradation of the viral small hydrophobic (SH) protein. We demonstrated that MARCH8 directly interacts with RSV-SH and catalyzes its ubiquitination at lysine 13, leading to SH degradation via the ubiquitin-lysosomal pathway. Functionally, MARCH8 expression enhances RSV-induced apoptosis through SH degradation, ultimately reducing viral titers. Conversely, an RSV strain harboring the SH-K13R mutation exhibited prolonged SH protein stability and attenuated apoptosis in infected cells, even in the presence of MARCH8. Targeted depletion of MARCH8 enhances cellular survival and potentially increases viral persistence. These findings demonstrate that MARCH8 promotes the early elimination of virus-infected cells by abrogating the anti-apoptotic function of SH, thereby reducing viral transmission. Our study provides novel insights into the interplay between host restriction factors and viral evasion strategies, potentially providing new therapeutic approaches for RSV infections.

PTH1R Suppressed Apoptosis of Mesenchymal Progenitors in Mandibular Growth.

Genetic abnormalities of the parathyroid hormone 1 receptor (PTH1R) lead to profound craniomaxillofacial bone and dentition defects on account of inappropriate tissue metabolism and cellular differentiation. The coordinated activity of differentiation and viability in bone cells is indispensable for bone metabolism. Recent research demonstrates mesenchymal progenitors are responsive to PTH1R signaling for osteogenic differentiation, whereas the effect of PTH1R on cellular survival remains incompletely understood. Here, we report that mice with deletion of PTH1R in Prx1-positive mesenchymal cells (Prx1Cre;PTH1Rfl/fl) exhibit decreased alveolar bone mass due in part to apoptotic response activation. The exploration of oral bone-derived mesenchymal stem cells (OMSCs) with PTH1R deficiency suggests PTH1R signaling modulates OMSCs' apoptosis by interfering mitochondrial function and morphology. The underlying molecular mechanisms are studied by transcriptome sequencing analysis, finding that inositol trisphosphate receptor-3 (IP3R-3), an endoplasmic reticulum calcium channel protein, serves as a modulator of pro-apoptosis in OMSCs. Furthermore, we find PTH1R and its downstream protein kinase A (PKA) pathway dampen IP3R-3's expression. Of note, OMSCs with IP3R-3 overexpression recapitulate the PTH1R-deletion phenotypes, while IP3R-3 silence rescues mitochondrial dysfunction. Altogether, our study uncovers the anti-apoptotic function of PTH1R signaling in OMSCs and proves that excess apoptosis partly contributes to a weakening potential of osteogenic differentiation and aberrant mandibular development.

An in vivo and in silico probing of the protective potential of betaine against sodium fluoride-induced neurotoxicity

Excessive fluoride exposure beyond the tolerable limit may adversely impacts brain functionality. Betaine (BET), a trimethyl glycine, possesses antioxidant, anti-inflammatory and anti-apoptotic functions, although the underlying mechanisms of the role of BET on fluoride-induced neurotoxicity remain unelucidated. To assess the mechanism involved in the neuro-restorative role of BET on behavioural, neurochemical, and histological changes, we employed a rat model of sodium fluoride (NaF) exposure. Animals were treated with NaF (9 mg/kg) body weight (bw) only or co-treated with BET (50 and 100 mg/kg bw) orally uninterrupted for 28 days. We obtained behavioural phenotypes in an open field, performed negative geotaxis, and a forelimb grip test, followed by oxido-inflammatory, apoptotic, and histological assessment. Behavioural endpoints indicated lessened locomotive and motor and heightened anxiety-like performance and upregulated oxidative, inflammatory, and apoptotic biomarkers in NaF-exposed rats. Co-treatment with BET significantly enhanced locomotive, motor, and anxiolytic performance, increased the antioxidant signalling mechanisms and demurred oxidative, inflammatory, and apoptotic biomarkers and histoarchitectural damage in the cerebrum and cerebellum cortices mediated by NaF. The in-silico analysis suggests that multiple hydrogen bonds and hydrophobic interactions of BET with critical amino acid residues, including arginine (ARG380 and ARG415) in the Keap1 Kelch domain, which may disrupt Keap1-Nrf2 complex and activate Nrf2. This may account for the observed increased in the Nrf2 levels, elevated antioxidant response and enhanced anti-inflammatory response. The BET-Keap1 complex was also observed to exhibit structural stability and conformational flexibility in solvated biomolecular systems, as indicated by the thermodynamic parameters computed from the trajectories obtained from a 100 ns full atomistic molecular dynamics simulation. Therefore, BET mediates neuroprotection against NaF-induced cerebro-cerebellar damage through rats’ antioxidant, anti-inflammatory, and anti-apoptotic activity, which molecular interactions with Keap1-Nrf2 may drive.

STC-1 alleviates airway inflammation by regulating epithelial cell apoptosis through the 5-LO pathway.

Airway inflammation plays a key role in the pathogenesis and development of asthma. Stanniocalcin-1 (STC-1) has powerful antioxidant, anti-inflammatory and anti-apoptotic functions but its impact on the airway inflammation in asthma lacks evidence. Here, we investigated the effect and potential mechanism of STC-1 on airway inflammation through asthmatic mice model and lipopolysaccharide (LPS)-treated BEAS-2B cells. The data showed that STC-1 treatment before the challenge exerted protective effect on ovalbumin (OVA)-induced asthmatic mice, i.e., decreased the inflammatory cell infiltration, mucus secretion, cytokine levels, apoptosis levels, and p38 MAPK signaling. Additionally, STC-1 reduced 5-LO expression. Meanwhile, STC-1 decreased p38 MAPK signaling, cytokine production, mucin MUC5AC production, 5-LO expression and nuclear translocation, and LTB4 production in vitro. Ultimately, transforming growth factor (TGF- ), as a 5-LO inducer, reversed the anti-inflammatory and anti-apoptotic effects of STC-1 in BEAS-2B cells by up-regulating 5-LO expression. It reveals the potential of STC-1 to act as an additional therapy to mitigate airway inflammation in asthma and inhibit 5-LO expression.

Molecular and structural analyses of voltage-dependent anion channel 2 and its anti-apoptotic function in stress and pollutant resistance in Pacific abalone

This study aimed to identify voltage-dependent anion channel 2 (Hdh-VDAC2) and determine its functional role in response to acute thermal stress, H2O2-induced stress, heavy metal toxicity, bacterial and viral infections, and during metamorphosis. Structural analysis confirmed that Hdh-VDAC2 is a pore-forming β-barrel protein. Molecular docking further confirmed the protein-protein interactions of Hdh-VDAC2 with Hdh-BAX, Hdh-caspase 3, and Hdh-BCL2. In the Hdh-VDAC2-inhibited hemocytes (HCY), apoptotic genes (Hdh-caspase-3 and Hdh-BAX) exhibited elevated mRNA expression, while the anti-apoptotic gene (Hdh-BCL2) was downregulated. Further, fluorescent techniques confirmed excessive reactive oxygen species (ROS) production, lower cell viability, elevated caspase 3 activity, and increased DNA fragmentation in Hdh-VDAC2-inhibited HCY, indicating an anti-apoptotic role of Hdh-VDAC2 in Pacific abalone. Transcriptomic analysis revealed differential expression patterns, with upregulation in the digestive gland (DG) and downregulation in the gill (GIL) and HCY when comparing heat-tolerant (HT) versus heat-sensitive (HS) abalone groups. Additionally, both cold and heat stresses induced Hdh-VDAC2 expression. Other environmental factors including H2O2, cadmium, bacteria, and viruses, were also shown to induce Hdh-VDAC2 mRNA expression in the GIL and DG of Pacific abalone. During metamorphosis, the blastula (BLS) stage exhibited higher Hdh-VDAC2 mRNA expression. These findings suggest that Hdh-VDAC2 plays a crucial anti-apoptotic role and may be a biomarker for summer mortality in Pacific abalone.

Association of Genetic Variants at the CDKN1B and CCND2 Loci Encoding p27Kip1 and Cyclin D2 Cell Cycle Regulators with Susceptibility and Clinical Course of Chronic Lymphocytic Leukemia.

Beyond the essential role of p27Kip1 and cyclin D2 in cell cycle progression, they are also shown to confer an anti-apoptotic function in peripheral blood (PB) lymphocytes. Although the aberrant longevity and expression of p27Kip1 and cyclin D2 in leukemic cells is well documented, the exact mechanisms responsible for this phenomenon have yet to be elucidated. This study was undertaken to determine the associations between polymorphisms in the CDKN1B and CCND2 genes (encoding p27Kip1 and cyclin D2, respectively) and susceptibility to chronic lymphocytic leukemia (CLL), as well as their influence on the expression of both cell cycle regulators in PB leukemic B cells and non-malignant T cells from untreated CLL patients divided according to the genetic determinants studied. Three CDKN1B single-nucleotide polymorphisms (SNPs), rs36228499, rs34330, and rs2066827, and three CCND2 SNPs, rs3217933, rs3217901, and rs3217810, were genotyped using a real-time PCR system. The expression of p27Kip1 and cyclin D2 proteins in both leukemic B cells and non-malignant T cells was determined using flow cytometry. We found that the rs36228499A and rs34330T alleles in CDKN1B and the rs3217810T allele in the CCND2 gene were more frequent in patients and were associated with increased CLL risk. Moreover, we observed that patients possessing the CCND2rs3217901G allele had lower susceptibility to CLL (most pronounced in the AG genotype). We also noticed that the presence of the CDKN1Brs36228499CC, CDKN1Brs34330CC, CDKN1Brs2066827TT, and CCND2rs3217901AG genotypes shortened the time to CLL progression. Statistically significant functional relationships were limited to T cells and assigned to CDKN1B polymorphic variants; carriers of the polymorphisms rs34330CC and rs36228499CC (determining the aggressive course of CLL) expressed a decrease in p27Kip1 and cyclin D2 levels, respectively. We indicate for the first time that genetic variants at the CDKN1B and CCND2 loci may be considered as a potentially low-penetrating risk factor for CLL and determining the clinical outcome.

The pro-apoptotic function of the C. elegans BCL-2 homolog CED-9 requires interaction with the APAF-1 homolog CED-4.

In Caenorhabditis elegans, apoptosis is inhibited by the BCL-2 homolog CED-9. Although canonically anti-apoptotic, CED-9 has a poorly understood pro-apoptotic function. CED-9 is thought to inhibit apoptosis by binding to and inhibiting the pro-apoptotic C. elegans APAF-1 homolog CED-4. We show that CED-9 or CED-4 mutations located in their CED-9-CED-4 binding regions reduce apoptosis without affecting the CED-9 anti-apoptotic function. These mutant CED-9 and CED-4 proteins are defective in a CED-9-CED-4 interaction in vitro and in vivo, revealing that the known CED-9-CED-4 interaction is required for the pro-apoptotic but not for the anti-apoptotic function of CED-9. The pro-apoptotic CED-9-CED-4 interaction occurs at mitochondria. In mammals, BCL-2 family members can activate APAF-1 via cytochrome c release from mitochondria. The conserved role of mitochondria in CED-9/BCL-2-dependent CED-4/APAF-1 activation is notable and suggests that understanding how CED-9 promotes apoptosis in C. elegans could inform the understanding of mammalian apoptosis and how disruptions of apoptosis promote certain human disorders.

Immunohistochemical Expression of the SERPINA3 Protein in Uterine Fibroids.

SERPINA3 (α-1-antichymotrypsin, AACT, ACT) is produced by the liver and released into plasma in an anti-inflammatory response and plays a role as a modulator of extracellular matrix (ECM) by inhibiting serine proteases. Numerous studies proved an increased level of SERPINA3 in many types of cancer, which could be linked to SERPINA3's anti-apoptotic function. In the context of progressive ECM fibrosis during the development of uterine fibroids, which are one of the most common hypertrophic changes within the uterus, it is interesting to describe the level of SERPINA3 protein in this type of lesion and the surrounding tissues. We used immunohistochemical staining of the SERPINA3 protein and compared the intensity of the signal between the myoma tissue and the surrounding normal tissue. We showed a surprising reduction in the amount of the SERPINA3 protein within uterine fibroids compared to surrounding tissues. This observation sheds new light on the role of this protein in the formation of proliferative changes and suggests that understanding the mechanism of its action may become the basis for the development of new diagnostic and therapeutic tools.

The Mitochondrial Ubiquitin Ligase MARCHF5 Cooperates with MCL1 to Inhibit Apoptosis in KSHV-Transformed Primary Effusion Lymphoma Cell Lines.

Kaposi's sarcoma-associated herpesvirus (KSHV) causes several malignancies in people with HIV including Kaposi's sarcoma and primary effusion lymphoma (PEL). We have previously shown that PEL cell lines require myeloid cell leukemia-1 (MCL1) to inhibit apoptosis. MCL1 is an oncogene that is amplified in cancers and causes resistance to chemotherapy regimens. MCL1 is thus an attractive target for drug development. The emerging clinical relevance and therapeutic potential of MCL1 motivated us to study the roles of this oncogene in PEL in depth. Using a systems biology approach, we uncovered an unexpected genetic interaction between MCL1 and MARCHF5 indicating that they function in the same pathway. MARCHF5 is an E3 ubiquitin ligase most known for regulating mitochondrial homeostasis and antiviral signaling, but not apoptosis. We thus investigated how MCL1 and MARCHF5 cooperate to promote PEL cell survival. CRISPR knockout (KO) of MARCHF5 in PEL cell lines resulted in a significant increase in apoptosis despite the presence of MCL1. The anti-apoptotic function of MARCHF5 was dependent on its E3 ligase and dimerization activities. Loss of MARCHF5 or inhibition of the 26S proteasome furthermore stabilized the MCL1 antagonist NOXA without affecting levels of MCL1. Interestingly, NOXA KO provides a fitness advantage to PEL cells suggesting that NOXA is the pro-apoptotic signal that necessitates the anti-apoptotic activities of MCL1 and MARCHF5. Finally, endogenous reciprocal co-immunoprecipitation experiments show that MARCHF5 and NOXA are found in the same protein complex. Our findings thus provide the mechanistic link that underlies the genetic interaction between MCL1 and MARCHF5. We propose that MARCHF5 induces the degradation of the MCL1 antagonist NOXA thus reinforcing the pro-survival role of MCL1 in these tumor cells. This newly appreciated interaction of the MCL1 and MARCHF5 oncogenes may be useful to improve the design of combination therapies for KSHV malignancies.

Evaluation of survivin expression and regulating miRNAs of survivin expression in peripheral blood mononuclear cells in systemic lupus erythematous patients.

Systemic lupus erythematosus is a multisystemic rheumatic disease with different clinical features. Disturbance in apoptosis regulation seems to be a major factor in SLE development. Survivin plays a key role in mitosis and inhibiting apoptosis. A study was conducted to examine the expression level of survivin and miRNAs that affect survivin transcript levels in patients with SLE. We isolated peripheral blood mononuclear cells from 50 inactive SLE patients and 50 healthy controls. RNA is extracted and converted to cDNA. The quantitative real-time polymerase chain reaction is conducted to assess the expression levels of survivin total and its variants with effective miRNAs in PBMCs. Expression levels of miR-34a-5p (fold change = 1.5, p++ = 0.027), and 218-5p (fold change = 1.5, p++ = 0.020) were significantly increased. While miR-150-5p (fold change = 0.56, p++ = 0.003) was significantly decreased. The mRNA expression of survivin-WT (fold change = 0.63, p++ = 0.002) was significantly downregulated in SLE patients compared to the healthy controls. Survivin total and its two major variants (survivin-2B, and survivin-ΔEx3) did not differ significantly between SLE patients and controls. Although survivin-TS and its two variants (survivin-2B, and survivin-ΔEx3) were not differently expressed in SLE patients, survivin-WT had altered expression. Despite aberrant miRNA expression in PBMCs from SLE patients, survivin and miRNA expression were not associated with leukopenia. The pathogenesis of SLE disorder might be linked to survivin's other roles in the immune system aside from anti-apoptotic functions.

Injectable hydrogel encapsulating siMMP13 with anti-ROS and anti-apoptotic functions for osteoarthritis treatment

BackgroundOsteoarthritis (OA) is a degenerative joint disease characterized by the progressive degeneration of articular cartilage, leading to pain, stiffness, and loss of joint function. The pathogenesis of OA involves multiple factors, including increased intracellular reactive oxygen species (ROS), enhanced chondrocyte apoptosis, and disturbances in cartilage matrix metabolism. These processes contribute to the breakdown of the extracellular matrix (ECM) and the loss of cartilage integrity, ultimately resulting in joint damage and dysfunction. RNA interference (RNAi) therapy has emerged as a promising approach for the treatment of various diseases, including hATTR and acute hepatic porphyria. By harnessing the natural cellular machinery for gene silencing, RNAi allows for the specific inhibition of target genes involved in disease pathogenesis. In the context of OA, targeting key molecules such as matrix metalloproteinase-13 (MMP13), which plays a critical role in cartilage degradation, holds great therapeutic potential.ResultsIn this study, we developed an innovative therapeutic approach for OA using a combination of liposome-encapsulated siMMP13 and NG-Monomethyl-L-arginine Acetate (L-NMMA) to form an injectable hydrogel. The hydrogel served as a delivery vehicle for the siMMP13, allowing for sustained release and targeted delivery to the affected joint. Experiments conducted on destabilization of the medial meniscus (DMM) model mice demonstrated the therapeutic efficacy of this composite hydrogel. Treatment with the hydrogel significantly inhibited the degradation of cartilage matrix, as evidenced by histological analysis showing preserved cartilage structure and reduced loss of proteoglycans. Moreover, the hydrogel effectively suppressed intracellular ROS accumulation in chondrocytes, indicating its anti-oxidative properties. Furthermore, it attenuated chondrocyte apoptosis, as demonstrated by decreased levels of apoptotic markers.ConclusionIn summary, the injectable hydrogel containing siMMP13, endowed with anti-ROS and anti-apoptotic properties, may represent an effective therapeutic strategy for osteoarthritis in the future.

ISL1-overexpressing BMSCs attenuate renal ischemia-reperfusion injury by suppressing apoptosis and oxidative stress through the paracrine action

Ischemia-reperfusion injury (IRI) is a major event in renal transplantation, leading to adverse outcomes. Bone marrow mesenchymal stem cells (BMSCs) are novel promising therapeutics for repairing kidney injuries. The therapeutic efficacy of BMSCs with ISL1 overexpression in renal IRI and its underlying mechanism need to be investigated. The unilateral renal IRI rat model was established to mimic clinical acute kidney injury. Rats were injected with PBS, BMSCs-Scrambled or BMSCs-ISL1 via the tail vein at the timepoint of reperfusion, and then sacrificed after 24 h of reperfusion. The administration of BMSCs-ISL1 significantly improved renal function, inhibited tubular cells apoptosis, inflammation, oxidative stress in rats. In vitro, HKC cells subjected to H2O2 stimulation were pretreated with the conditioned medium (CM) of BMSCs-Scrambled or BMSCs-ISL1. The pretreatment of ISL1-CM attenuated apoptosis and oxidative stress induced by H2O2 in HKC cells. Our proteomic data suggested that haptoglobin (Hp) was one of the secretory proteins in ISL1-CM. Subsequent experiments confirmed that Hp was the important paracrine factor from BMSCs-ISL1 that exerted anti-apoptotic and antioxidant functions. Mechanistically, Hp played a cytoprotective role via the inhibition of ERK signaling pathway, which could be abrogated by Ro 67-7476, the ERK phosphorylation agonist. The results suggested that paracrine action may be the main mechanism for BMSCs-ISL1 to exert protective effects. As an important anti-apoptotic and antioxidant factor in ISL1-CM, Hp may serve as a new therapeutic agent for treating IRI, providing new insights for overcoming the long-term adverse effects of stem cell therapy.

Enhancing carboplatin sensitivity in ovarian cancer cells by blocking the mercapturic acid pathway transporter.

Ral-binding/interacting protein (RLIP) acts as a transporter that responds to stress and provides protection, specifically against glutathione-electrophile conjugates and xenobiotic toxins. Its increased presence in malignant cells, especially in cancer, emphasizes its crucial antiapoptotic function. This is achieved by selectively regulating the cellular levels of proapoptotic oxidized lipid byproducts. Suppressing the progression of tumors in human xenografts can be achieved by effectively inhibiting RLIP, a transporter in the mercapturic acid pathway, without involving chemotherapy. Utilizing ovarian cancer (OC) cell lines (MDAH2774, OVCAR4, and OVCAR8), we observed that agents targeting RLIP, such as RLIP antisense and RLIP antibodies, not only substantially impeded the viability of OC cells but also remarkably increased their sensitivity to carboplatin. To delve further into the cytotoxic synergy between RLIP antisense, RLIP antibodies, and carboplatin, we conducted investigations in both cell culture and xenografts of OC cells. The outcomes revealed that RLIP depletion via phosphorothioate antisense led to rapid and sustained remissions in established subcutaneous human ovary xenografts. Furthermore, RLIP inhibition by RLIP antibodies exhibited comparable efficacy to antisense and enhanced the effectiveness of carboplatin in MDAH2774 OC xenografts. These investigations underscore RLIP as a central carrier crucial for supporting the survival of cancer cells, positioning it as a suitable focus for cancer treatment.

Protective effect of clusterin against interleukin-1β-induced apoptosis and inflammation in human knee osteoarthritis chondrocytes.

Chondrocyte apoptosis is recognized as one of the pathological features involved in cartilage degeneration driving the onset and progression of knee osteoarthritis (OA). This study aimed to determine the molecular mechanism underlying the effect of clusterin (CLU), anti-apoptotic molecule, in human knee OA chondrocytes. Primary knee OA chondrocytes were isolated from the cartilage of knee OA patients and divided into five groups: (1) the cells treated with interleukin (IL)-1β, (2) CLU alone, (3) a combination of IL-1β and CLU, (4) LY294002 (PI3K inhibitor) along with IL-1β and CLU, and (5) the untreated cells. Production of apoptotic, inflammatory, anabolic, and catabolic mediators in knee OA chondrocytes was determined after treatment for 24 h. Our in vitro study uncovered that CLU significantly suppressed the production of inflammatory mediators [nitric oxide (NO), IL6, and tumor necrosis factor (TNF)-α] and apoptotic molecule (caspase-3, CASP3). CLU significantly upregulated messenger ribonucleic acid (mRNA) expressions of anabolic factors [SRY-box transcription factor-9 (SOX9) and aggrecan (ACAN)], but significantly downregulated mRNA expressions of IL6, nuclear factor kappa-B (NF-κB), CASP3, and matrix metalloproteinase-13 (MMP13). Anti-apoptotic and anti-inflammatory effects of CLU were mediated through activating PI3K/Akt signaling pathway. The findings suggest that CLU might have beneficial effects on knee OA chondrocytes by exerting anti-apoptotic and anti-inflammatory functions via PI3K/Akt pathway, making CLU a promising target for potential therapeutic interventions in knee OA.

Therapies for Cirrhotic Cardiomyopathy: Current Perspectives and Future Possibilities.

Cirrhotic cardiomyopathy (CCM) is defined as cardiac dysfunction associated with cirrhosis in the absence of pre-existing heart disease. CCM manifests as the enlargement of cardiac chambers, attenuated systolic and diastolic contractile responses to stress stimuli, and repolarization changes. CCM significantly contributes to mortality and morbidity in patients who undergo liver transplantation and contributes to the pathogenesis of hepatorenal syndrome/acute kidney injury. There is currently no specific treatment. The traditional management for non-cirrhotic cardiomyopathies, such as vasodilators or diuretics, is not applicable because an important feature of cirrhosis is decreased systemic vascular resistance; therefore, vasodilators further worsen the peripheral vasodilatation and hypotension. Long-term diuretic use may cause electrolyte imbalances and potentially renal injury. The heart of the cirrhotic patient is insensitive to cardiac glycosides. Therefore, these types of medications are not useful in patients with CCM. Exploring the therapeutic strategies of CCM is of the utmost importance. The present review summarizes the possible treatment of CCM. We detail the current status of non-selective beta-blockers (NSBBs) in the management of cirrhotic patients and discuss the controversies surrounding NSBBs in clinical practice. Other possible therapeutic agents include drugs with antioxidant, anti-inflammatory, and anti-apoptotic functions; such effects may have potential clinical application. These drugs currently are mainly based on animal studies and include statins, taurine, spermidine, galectin inhibitors, albumin, and direct antioxidants. We conclude with speculations on the future research directions in CCM treatment.

Genomic properties of a Bartonella quintana strain from Japanese macaque (Macaca fuscata) revealed by genome comparison with human and rhesus macaque strains

Bartonella quintana, the causative agent of trench fever, is an intracellular bacterium that infects human erythrocytes and vascular endothelial cells. For many years, humans were considered the only natural hosts for B. quintana; however, it was recently discovered that wild Japanese macaques (Macaca fuscata) also serve as hosts for B. quintana. To elucidate the genetic characteristics of the B. quintana strain MF1-1 isolated from a Japanese macaque, we determined the complete genome sequence of the strain and compared it with those of strain Toulouse from a human and strain RM-11 from a rhesus macaque. General genomic features and orthologous gene cluster profiles are similar among the three strains, and strain MF1-1 is genetically closer to strain RM-11 than strain Toulouse based on the average nucleotide identity values; however, a significant inversion of approximately 0.68 Mb was detected in the chromosome of strain MF1-1. Moreover, the Japanese macaque strains lacked the bepA gene, which is responsible for anti-apoptotic function, and the trwL2, trwL4, and trwL6 genes, which may be involved in adhesion to erythrocytes of rhesus macaque and human. These features likely represent the genomic traits acquired by Japanese macaque strains in their host-associated evolution.

Lamprey VDAC2: Suppressing hydrogen peroxide-induced 293T cell apoptosis by downregulating BAK expression

The voltage-dependent anion channel 2 (VDAC2) is the abundant protein in the outer mitochondrial membrane. Opening VDAC2 pores leads to the induction of mitochondrial energy and material transport, facilitating interaction with various mitochondrial proteins implicated in essential processes such as cell apoptosis and proliferation. To investigate the VDAC2 in lower vertebrates, we identified Lr-VDAC2, a homologue of VDAC2 found in lamprey (Lethenteron reissneri), sharing a sequence identity of greater than 50 % with its counterparts. Phylogenetic analysis revealed that the position of Lr-VDAC2 aligns with the lamprey phylogeny, indicating its evolutionary relationship within the species. The Lr-VDAC2 protein was primarily located in the mitochondria of lamprey cells. The expression of the Lr-VDAC2 protein was elevated in high energy-demanding tissues, such as the gills, muscles, and myocardial tissue in normal lampreys. Lr-VDAC2 suppressed H2O2 (hydrogen peroxide)-induced 293 T cell apoptosis by reducing the expression levels of Caspase 3, Caspase 9, and Cyt C (cytochrome c). Further research into the mechanism indicated that the Lr-VDAC2 protein inhibited the pro-apoptotic activity of BAK (Bcl-2 antagonist/killer) protein by downregulating its expression at the protein translational level, thus exerting an anti-apoptotic function similar to the role of VDAC2 in humans.

Abstract PO2-24-08: GD3 Synthase is a Master Regulator of Wild-Type p53–Mediated Apoptosis and Mutant p53–Mediated Tumorigenesis

Abstract The tumor suppressor protein p53 is essential for maintaining genomic stability and regulating cellular responses to stress. TP53 mutations are common in breast cancer (BC) and other malignancies. We previously showed that ganglioside GD2 identifies BC stem-like cells (BCSCs) and that GD3 synthase (GD3S/ST8SIA1) is upregulated in breast tumors with TP53 mutations. Here, we demonstrate the direct involvement of p53 in the transcriptional regulation of GD3S in the GD2 biosynthesis pathway. Our results uncover a novel role of GD3S in inhibiting p53-mediated apoptosis and promoting mutant p53–induced tumor initiation. To investigate the p53-mediated regulation of GD3S expression, we used the TCGA and METABRIC datasets and examined GD3S mRNA expression in breast tumors with different p53 mutation status. GD3S expression was significantly upregulated in BC patients with hotspot (HS) p53 mutations compared to those with wild-type (WT) p53 or non-HS p53 mutations (P< 0.0001). Immuno-histochemical analysis of GD3S and p53 in FFPE primary tumor tissues from BC patients (n=84) with varying p53 expression status demonstrated that patients with HS p53 mutations had higher histological scores for GD3S than did patients with WT p53 (P< 0.0001) or non-HS p53 mutations (P=0.009). GD3S and p53 expression were significantly positively correlated in patients with HS p53 mutations (r=0.735; P=0.006) but not in patients with WT p53 (r=–0.09) or non-HS p53 mutations (r=0.14). Consistent with these patient data, BC cells harboring HS p53 mutations had significantly upregulated and positively correlated expressions of GD3S and p53 (n=8; r=0.85). Moreover, compared to those with WT p53, the cells with HS p53 mutations had substantially greater populations of GD2+ BCSCs (P=0.02) and GD3+ BCSCs (P=0.01). Subsequently, we investigated the regulatory role of p53 in the GD2 biosynthetic pathway by stabilizing WT p53 expression by nutlin-3a treatment in 4 BC cell lines and suppressing the expression of HS p53 mutants by p53 knockdown in their respective cell lines (n=4). In cell lines with WT p53, nutlin-3a significantly decreased GD3S expression and GD2 levels (P< 0.05 and P< 0.0001, respectively), suggesting that WT p53 inhibits GD3S expression. In cell lines with p53 mutations, p53 knockdown significantly inhibited GD3S expression. In both cells with WT p53 (MCF7 and ZR751) and cells with HS p53 mutations (Hs578T and BT549), the stable overexpression of GD3S effectively suppressed apoptosis even when WT p53 was stabilized or HS p53 mutant expression was depleted. Consistent with these results, in mice bearing MCF7 cell–derived xenografts, the overexpression of GD3S counteracted the effect of stabilized WT p53–mediated apoptosis and facilitated tumor growth (P< 0.0001). The results of a promoter-luciferase reporter assay demonstrated that nutlin-3a reduced GD3S promoter activity in a dose-dependent manner in MCF7 and ZR751 cells (P< 0.0001), whereas doxycycline (1µM) significantly reduced GD3S promoter activity in Hs578T and BT549 cells with inducible p53 knockdown (P< 0.001). ChIP-qPCR analysis confirmed specific enrichment of WT p53 at the 300-bp upstream regions and additional enrichment of HS p53 mutants at the downstream regions of the GD3S promoter, indicating that WT p53 and HS p53 mutations have distinct promoter regulation patterns. In summary, our study reveals that GD3S has a previously unknown anti-apoptotic function in BC, in that it helps attenuate p53-mediated apoptosis while activating tumor-promoting pathways that operate independently of p53. Citation Format: Vivek Anand, FOUAD EL-DANA, JENNY BORGMAN, MICHAEL ANDREEFF, Venkata Lokesh Battula. GD3 Synthase is a Master Regulator of Wild-Type p53–Mediated Apoptosis and Mutant p53–Mediated Tumorigenesis [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-24-08.