Inhibit Protein Kinase Research Articles

Rosehip Phytochemicals: A Computational Approach for Inhibiting Protein Kinase C Delta in Hepatocellular Carcinoma Treatment

Hepatocellular carcinoma is a primary liver cancer that is responsible for a significant number of cancer-related deaths worldwide. The development and progression of hepatocellular carcinoma is a complex process that involves various signalling pathways and molecular mechanisms. One such pathway is the protein kinase C delta pathway, which has been shown to play a critical role in the development and progression of hepatocellular carcinoma. Diagnosis of hepatocellular carcinoma employs different techniques including use of imaging tools and biomarkers such as alpha-fetoprotein, des-gamma-carboxyprothrombin, Glypican-3, and protein kinase C delta. protein kinase C delta is a member of the protein kinase C family of serine/threonine kinases that regulates various cellular processes, including cell proliferation and differentiation. Inhibition of protein kinase C delta has been proposed as a potential therapeutic strategy for hepatocellular carcinoma. Several protein kinase C delta inhibitors have been developed and tested in preclinical studies, and some have shown promising results in inhibiting hepatocellular carcinoma cell proliferation and inducing apoptosis. Rosehip of various Rosa species are rich in biologically active compound which possess therapeutic properties such as anti-inflammatory, anti-cancerous and hepato-protectant. This study employs various bioinformatic tools to assess molecular, biological, and pharmacological activity of phytochemicals present in rosehip against protein kinase C delta. In order to choose hit compounds, a number of factors are taken into account, including biological activity, binding affinity (docking score), pharmacokinetics, physiochemical characteristics, physicochemical properties, ADME/t properties, and biological activity. Six compounds (quercetin, luteolin, p-coumaric acid, gallic acid, ferulic acid, and caffeine) out of 14 docked compounds matched the requirements. These six phytochemicals might be studied in vitro and in vivo to determine their effectiveness and efficiency.

Bioactive fractions from Allium humile alleviate the risk of high fat diet induced atherosclerosis in albino Wistar rats by inhibiting protein kinase C

Atherosclerosis is a global concern that worsens with age, and plants that are effective medicinal herbs can give a viable alternative. PKC is a key factor in cardiovascular and other disorders; targeting it can reduce the risk of these diseases. We evaluated Allium humile for PKC inhibition and therapeutic efficacy against atherosclerosis. Soxhlet extraction was done to obtain extracts (hexane, ethyl acetate, methanol, ethanol and aqueous) and then tested for DPPH radical scavenging and PKC inhibitory activity. The methanolic extract was more active than the other extracts, so it was subjected to column chromatography, and seventeen fractions were obtained. Only 11, 12, and 15 showed good activity against PKC. Wistar rats were divided into six groups and each group received high fat diet for 30 days. Then the three potent fractions (10 mg/kg) were administered for 15 days along with high fat diet. Fraction II had the highest effectiveness (P < 0.0001) in decreasing lipid levels, lipid peroxidation, reducing IL-6 and TNF-α expression, and raising nitric oxide. This also demonstrated a decrease in PKC activity, as well as a decrease in the formation of the lipoidal layer in the aorta wall and rupture of the intima and media as validated by histological analysis. The two compounds, phytol acetate and cyanidin 3-(6″-o-malonyllaminaribioside) were characterised in fraction II by NMR and HRMS and cyanidin 3-(6″-o-malonyllaminaribioside) inhibited PKC more efficiently. Thus, Allium humile has strong anti-atherogenic activity as well as the ability to inhibit PKC both in vitro and in vivo.

Menin Reduces Parvalbumin Expression and is Required for the Anti-Depressant Function of Ketamine.

Dysfunction of parvalbumin (PV) neurons is closely involved in depression, however, the detailed mechanism remains unclear. Based on the previous finding that multiple endocrine neoplasia type 1 (Protein: Menin; Gene: Men1) mutation (G503D) is associated with a higher risk of depression, a Menin-G503D mouse model is generated that exhibits heritable depressive-like phenotypes and increases PV expression in brain. This study generates and screens a serial of neuronal specific Men1 deletion mice, and found that PV interneuron Men1 deletion mice (PcKO) exhibit increased cortical PV levels and depressive-like behaviors. Restoration of Menin, knockdown PV expression or inhibition of PV neuronal activity in PV neurons all can ameliorate the depressive-like behaviors of PcKO mice. This study next found that ketamine stabilizes Menin by inhibiting protein kinase A (PKA) activity, which mediates the anti-depressant function of ketamine. These results demonstrate a critical role for Menin in depression, and prove that Menin is key to the antidepressant function of ketamine.

Inhibitory effect of liriopesides B in combination with gemcitabine on human pancreatic cancer cells

Gemcitabine (GEM) is a standard chemotherapeutic agent for patients with pancreatic cancer; however, GEM-based chemotherapy has a high rate of toxicity. A combination of GEM and active constituents from natural products may enhance its therapeutic efficacy and reduce its toxicity. This study investigated the synergistic effects of the combination of liriopesides B (LirB) from Liriope spicata var. prolifera and GEM on human pancreatic cancer cells. The results of our study showed that the combination of LirB and GEM synergistically decreased the viability of pancreatic cancer cells. The combination also caused a strong increase in apoptosis and a strong decrease in cell migration and invasion. Furthermore, LirB combined with GEM had potent inhibitory effects on pancreatic cancer stem cells (CSCs). Studies on the mechanisms of action showed that the combination more potently inhibited protein kinase B (Akt) and nuclear factor kappa B (NF-κB), as well as the downstream antiapoptotic molecules B-cell lymphoma 2 (Bcl-2) and survivin than either agent used alone. The results of this study suggest that the combination of LirB with GEM may improve the efficacy of GEM for the treatment of pancreatic cancer.

Sargachromenol Attenuates Inflammatory Responses by Regulating NF-κB and Nrf2 Pathways in RAW 264.7 Cells and LPS-treated Mice.

This study aims to explore the anti-inflammatory mechanisms of sargachromenol in both RAW 264.7 cells and lipopolysaccharide (LPS)-treated mice, as previous reports have suggested that sargachromenol possesses anti-aging, anti-inflammatory, antioxidant, and neuroprotective properties. Although the precise mechanism behind its anti-inflammatory activity remains unclear, pretreatment with sargachromenol effectively reduced the production of nitric oxide, prostaglandin E2, and interleukin (IL)-1β in LPS-stimulated RAW 264.7 cells by inhibiting cyclooxygenase-2. Moreover, sargachromenol inhibited the activation of nuclear factor-κB (NF-κB) by preventing the degradation of the inhibitor of κB-α (IκB-α) and inhibiting protein kinase B (Akt) phosphorylation in LPS-stimulated cells. We also found that sargachromenol induced the production of heme oxygenase-1 (HO-1) by activating the nuclear transcription factor erythroid-2-related factor 2 (Nrf2). In LPS-treated mice, oral administration of sargachromenol effectively reduced the levels of IL-1β, IL-6, and tumor necrosis factor-α (TNF-α) in the serum, suggesting its ability to suppress the production of inflammatory mediators by inhibiting the Akt/NF-κB pathway and upregulating the Nrf2/HO-1 pathway.

Distinct molecular targets of ProEGCG from EGCG and superior inhibition of angiogenesis signaling pathways for treatment of endometriosis

Endometriosis is a common chronic gynecological disease with endometrial cell implantation outside the uterus. Angiogenesis is a major pathophysiology in endometriosis. Our previous studies have demonstrated that the prodrug of epigallocatechin gallate (ProEGCG) exhibits superior anti-endometriotic and anti-angiogenic effects compared to epigallocatechin gallate (EGCG). However, their direct binding targets and underlying mechanisms for the differential effects remain unknown. In this study, we demonstrated that oral ProEGCG can be effective in preventing and treating endometriosis. Additionally, 1D and 2D Proteome Integral Solubility Alteration assay-based chemical proteomics identified metadherin (MTDH) and PX domain containing serine/threonine kinase-like (PXK) as novel binding targets of EGCG and ProEGCG, respectively. Computational simulation and BioLayer interferometry were used to confirm their binding affinity. Our results showed that MTDH-EGCG inhibited protein kinase B (Akt)-mediated angiogenesis, while PXK-ProEGCG inhibited epidermal growth factor (EGF)-mediated angiogenesis via the EGF/hypoxia-inducible factor (HIF-1a)/vascular endothelial growth factor (VEGF) pathway. In vitro and in vivo knockdown assays and microvascular network imaging further confirmed the involvement of these signaling pathways. Moreover, our study demonstrated that ProEGCG has superior therapeutic effects than EGCG by targeting distinct signal transduction pathways and may act as a novel antiangiogenic therapy for endometriosis.

Tamoxifen as an effective treatment for refractory mania: a case report

Tamoxifen is a medication that acts as a selective estrogen receptor modulator (SERM) by inhibiting protein kinase C (PKC). It has various effects on different tissues in the body, depending on whether the tissue expresses estrogen receptors. For instance, it can reduce inflammation and neuronal excitability. Several studies have shown that tamoxifen could be effective in treating refractory mania, a type of mania that has shown resistance to mood stabilizers and other treatments. The rationale for its use could be explained by the fact that PKC is an enzyme that seemingly plays a significant role in the genesis of mania. We present the case of a 43-year-old female patient with bipolar disorder, who has had 43 previous hospitalizations and has undergone multiple treatments. Management with tamoxifen was initiated to control the manic episode.

Gastrodin destabilizes survivin and overcomes pemetrexed resistance

Survivin is a bifunctional protein that plays crucial roles in tumorigenesis. In the present study, we discovered that the natural product gastrodin suppressed the cell viability and colony formation of non-small cell lung cancer (NSCLC) cell lines A549, HCC827, and H460 in a dose-dependent manner. In addition, gastrodin enhanced the protein levels of cleaved-caspase 3 by activating the endogenous mitochondrial apoptosis pathway. Gastrodin inhibits protein kinase B (Akt)/WEE1/cyclin-dependent kinase 1 (CDK1) signaling to downregulate survivin Thr34 phosphorylation. Survivin Thr34 dephosphorylation caused by gastrodin interfered with the binding of ubiquitin-specific protease 19 (USP19), which eventually destabilized survivin. We revealed that the growth of NSCLC xenograft tumors was markedly suppressed by gastrodin in vivo. Furthermore, gastrodin overcomes pemetrexed resistance in vivo or in vitro. Our results suggest that gastrodin is a potential antitumor agent by reducing survivin in NSCLC.

Fascinating Furanosteroids and Their Pharmacological Profile.

This review article delves into the realm of furanosteroids and related isoprenoid lipids derived from diverse terrestrial and marine sources, exploring their wide array of biological activities and potential pharmacological applications. Fungi, fungal endophytes, plants, and various marine organisms, including sponges, corals, molluscs, and other invertebrates, have proven to be abundant reservoirs of these compounds. The biological activities exhibited by furanosteroids and related lipids encompass anticancer, cytotoxic effects against various cancer cell lines, antiviral, and antifungal effects. Notably, the discovery of exceptional compounds such as nakiterpiosin, malabaricol, dysideasterols, and cortistatins has revealed their potent anti-tuberculosis, antibacterial, and anti-hepatitis C attributes. These compounds also exhibit activity in inhibiting protein kinase C, phospholipase A2, and eliciting cytotoxicity against cancer cells. This comprehensive study emphasizes the significance of furanosteroids and related lipids as valuable natural products with promising therapeutic potential. The remarkable biodiversity found in both terrestrial and marine ecosystems offers an extensive resource for unearthing novel biologically active compounds, paving the way for future drug development and advancements in biomedical research. This review presents a compilation of data obtained from various studies conducted by different authors who employed the PASS software 9.1 to evaluate the biological activity of natural furanosteroids and compounds closely related to them. The utilization of the PASS software in this context offers valuable advantages, such as screening large chemical libraries, identifying compounds for subsequent experimental investigations, and gaining insights into potential biological activities based on their structural features. Nevertheless, it is crucial to emphasize that experimental validation remains indispensable for confirming the predicted activities.

Cyclic thrombocytopenia associated with estradiol: a case report

ABSTRACTObjectivesCyclic thrombocytopenia (CTP) is a rare blood disorder characterized by periodic fluctuations in platelet counts. CTP usually appears in pre-menopausal women, and these fluctuations of platelets are in phase with the menstrual cycle. CTP is a heterogeneous disease, and the pathogenic mechanism is still unclear. Therefore, it harbors great significance for exploring the association of fluctuations in platelet counts with hormonal-cycle.MaterialsFirstly, we washed human platelets from healthy volunteers following the Declaration of Helsinki. Flow cytometer was employed to measure the mitochondrial inner transmembrane potential (ΔΨm) depolarization, PS exposure, P-selectin expression, and GPIIb/IIIa activation in platelets. In addition, western blot detected the related protein expression. The corresponding assay kit measured the caspase-3 and PDE3A activity. Finally, flow cytometry determined mouse platelets labeled with calcein.ResultsWe find a reverse relationship between the platelet count and serum estradiol (E2) level in a CTP patient. We demonstrated that E2 induces platelet apoptosis in vitro and platelet clearance in vivo. We further discovered that E2 activates phosphodiesterase 3A, which inhibits protein kinase A (PKA), leading to PKA-mediated platelet apoptosis. Activation of PKA protected platelets from E2-induced thrombocytopenia and elevated the number of mice circulatory platelets.ConclusionsWe find that E2 induces platelet apoptosis and clearance through PDE3A-mediated PKA inhibition. Activation of PKA rescues E2-induced thrombocytopenia in mice. Thus, our study reveals a pathogenesis of E2-related CTP and suggests promising therapeutic strategies for the disease.

Effects of Simvastatin on RBL-2H3 Cell Degranulation.

Hypercholesterolemia is a major complication of arteriosclerosis. Mast cells in arteriosclerosis plaques induce inflammatory reactions and promote arterial sclerosis. In this study, we evaluated the pharmacological effects of simvastatin (SV)-3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase inhibitors on the degranulation of rat basophilic leukemia (RBL)-2H3 cells, which are commonly used as mast cell models. SV significantly decreased the degranulation induced by three types of stimulation: antigen antibody reaction (Ag-Ab), thapsigargin (Tg) serosal endoplasmic reticulum calcium ATPase (SERCA) inhibitor, and A23187 calcium ionophore. SV had a stronger inhibitory effect on degranulation induced by Ag-Ab stimulation than the other two stimulations. However, SV did not inhibit increase of intracellular Ca2+ concentrations. Mevalonate or geranylgeraniol co-treatment with SV completely prevented the inhibitory effect of SV on the degranulation induced by these stimulations. Immunoblotting results showed that SV inhibited protein kinase C (PKC) delta translocation induced by Ag-Ab but not by Tg or A23187. SV induced a reduction in active Rac1, and actin filament rearrangement. In conclusion, SV inhibits RBL-2H3 cell degranulation by inhibiting downstream signaling pathways, including the sequential degranulation pathway. These inhibitory effects were completely reversed by the addition of geranylgeraniol and might be induced by changes in the translocation of the small guanosine 5'-triphosphatase (GTPase) families Rab and Rho, which are related to vesicular transport PKC delta translocation and actin filament formation, respectively. These changes are caused by the inhibition of HMG-CoA reductase by SV following the synthesis of geranylgeranyl pyrophosphates, which play important roles in the activation of small GTPases, Rab.

ICP4-Associated Activation of Rap1b Facilitates Herpes Simplex Virus Type I (HSV-1) Infection in Human Corneal Epithelial Cells.

The strong contribution of RAS-related protein 1b (Rap1b) to cytoskeleton remodeling determines intracellular and extracellular physiological activities, including the successful infection of viruses in permissive cells, but its role in the HSV-1 life cycle is still unclear. Here, we demonstrated that the HSV-1 immediate early (IE) gene ICP4 inhibits protein kinase A (PKA) phosphorylation to induce Rap1b-activation-mediated viral infection. Rap1b activation and membrane enrichment begin at the early stage of HSV-1 infection and remain active during the proliferation period of the virus. Treating the cells with Rap1b small interfering RNA (siRNA) showed a dose-dependent decrease in viral infection levels, but no dose-dependent increase was observed after Rap1b overexpression. Further investigation indicated that the suppression of Rap1b activation derives from phosphorylated PKA and Rap1b mutants with partial or complete prenylation instead of phosphorylation, which promoted viral infection in a dose-dependent manner. Furthermore, the PKA agonist Forskolin disturbed Rap1b activation in a dose-dependent manner, accompanied by a decreasing trend in viral infection. Moreover, the HSV-1 IE gene ICP4 induced PKA dephosphorylation, leading to continuous Rap1b activation, followed by cytoskeleton rearrangement induced by cell division control protein 42 (CDC42) and Ras-related C3 botulinum toxin substrate 1 (RAC1). These further stimulated membrane-triggered physiological processes favoring virus infection. Altogether, we show the significance of Rap1b during HSV-1 infection and uncover the viral infection mechanism determined by the posttranslational regulation of the viral ICP4 gene and Rap1b host protein.

A randomized phase 2 non-inferiority trial of (Z)-endoxifen and exemestane + goserelin as neoadjuvant treatment for premenopausal women with ER+/HER2- breast cancer (EVANGELINE).

TPS633 Background: Ovarian function suppression (OFS) when combined with tamoxifen or an aromatase inhibitor is the standard of care for premenopausal estrogen receptor positive (ER+) human epidermal growth factor receptor 2 negative (HER2-) breast cancer (BC) based on SOFT (Francis 2022) and TEXT (Pagani 2022) clinical trials and confirmed in a metanalysis (EBCTCG 2022). However, estrogen deprivation in premenopausal women is associated with significant morbidity and up to 40% of premenopausal women with ER+/HER2- BC are intolerant of OFS. For these women, tamoxifen monotherapy is the only FDA approved option. Therefore, there is substantial room to improve endocrine therapy for premenopausal women with ER+/HER2- BC. (Z)-endoxifen is one of the most active anti-estrogen tamoxifen metabolites, with preclinical data demonstrating superiority to tamoxifen and letrozole in aromatase expressing xenograft models and evidence for antitumor activity in early phase clinical trials in patients with prior progression on endocrine therapy including tamoxifen. In addition to its ability to potently block ERa, (Z)-endoxifen at clinically achievable concentrations inhibits protein kinase C beta 1 (PKCβ1), resulting in downstream AKT inhibition and apoptosis. It is hypothesized that (Z)-endoxifen, when delivered as monotherapy at doses that dually target both ERα and PKCβ1, will potently inhibit BC proliferation while obviating the need for OFS in premenopausal women. If successful, this innovative approach could spare women with endocrine sensitive BC from the side effects of OFS. Methods: To further study (Z)-endoxifen in premenopausal women, a multicenter study in the United States, with possible expansion to other countries was designed (EVANGELINE; NCT05607004). This is a Phase 2, open-label, randomized, neoadjuvant study in premenopausal women with Stage IIA or IIB ER+/HER2- BC. Subjects are randomized 1:1 to either exemestane plus goserelin or (Z)-endoxifen. The primary objective is to determine whether the endocrine sensitive disease (ESD) rate (defined as Ki-67 ≤ 10% after 4 weeks of neoadjuvant therapy) with (Z)-endoxifen is non-inferior to exemestane plus goserelin. Subjects will be enrolled with the intent of surgical treatment in the involved breast(s) after completing 6 months of neoadjuvant treatment. Safety, tolerability, response rates and surgical outcomes will be assessed. Disease progression will be monitored throughout study participation. Paired tumor biopsies and blood sampling will allow for a robust biomarker evaluation. Prior to initiating the Treatment Cohort (162 subjects), up to 12 subjects will be enrolled in a pharmacokinetic (PK) Run-in Cohort to identify the optimal dose for the Treatment Cohort. Enrolment in the PK Run-in cohort began in February 2023. Clinical trial information: NCT05607004 .

Selenium deficiency-induced high concentration of reactive oxygen species restricts hypertrophic growth of skeletal muscle in juvenile zebrafish by suppressing TORC1-mediated protein synthesis.

Se deficiency causes impaired growth of fish skeletal muscle due to the retarded hypertrophy of muscle fibres. However, the inner mechanisms remain unclear. According to our previous researches, we infer this phenomenon is associated with Se deficiency-induced high concentration of reactive oxygen species (ROS), which could suppress the target of rapamycin complex 1 (TORC1) pathway-mediated protein synthesis by inhibiting protein kinase B (Akt), an upstream protein of TORC1. To test this hypothesis, juvenile zebrafish (45 d post-fertilisation) were fed a basal Se-adequate diet or a basal Se-deficient diet or them supplemented with an antioxidant (DL-α-tocopherol acetate, designed as VE) or a TOR activator (MHY1485) for 30 d. Zebrafish fed Se-deficient diets exhibited a clear Se-deficient status in skeletal muscle, which was not influenced by dietary VE and MHY1485. Se deficiency significantly elevated ROS concentrations, inhibited Akt activity and TORC1 pathway, suppressed protein synthesis in skeletal muscle, and impaired hypertrophy of skeletal muscle fibres. However, these negative effects of Se deficiency were partly (except that on ROS concentration) alleviated by dietary MHY1485 and completely alleviated by dietary VE. These data strongly support our speculation that Se deficiency-induced high concentration of ROS exerts a clear inhibiting effect on TORC1 pathway-mediated protein synthesis by regulating Akt activity, thereby restricting the hypertrophy of skeletal muscle fibres in fish. Our findings provide a mechanistic explanation for Se deficiency-caused retardation of fish skeletal muscle growth, contributing to a better understanding of the nutritional necessity and regulatory mechanisms of Se in fish muscle physiology.

Resveratrol Enhances Cytotoxic Effects of Cisplatin by Inducing Cell Cycle Arrest and Apoptosis in Ovarian Adenocarcinoma SKOV-3 Cells through Activating the p38 MAPK and Suppressing AKT.

In the current study, we identified a mechanism of resveratrol (RES) underlying its anti-cancer properties against human ovarian adenocarcinoma SKOV-3 cells. We investigated its anti-proliferative and apoptosis-inducing effects in combination with cisplatin, using cell viability assay, flow cytometry, immunofluorescence study and Western blot analysis. We discovered that RES suppressed cancer cell proliferation and stimulated apoptosis, especially when combined with cisplatin. This compound also inhibited SKOV-3 cell survival, which may partly be due to its potential to inhibit protein kinase B (AKT) phosphorylation and induce the S-phase cell cycle arrest. RES in combination with cisplatin strongly induced cancer cell apoptosis through activating the caspase-dependent cascade, which was associated with its ability to stimulate nuclear phosphorylation of p38 mitogen-activated protein kinase (MAPK), well recognized to be involved in transducing environmental stress signals. RES-induced p38 phosphorylation was very specific, and the activation status of extracellular signal-regulated kinase 1/2 (ERK1/2) and c-Jun N-terminal kinase (JNK) was not mainly affected. Taken together, our study provides accumulated evidence that RES represses proliferation and promotes apoptosis in SKOV-3 ovarian cancer cells through activating the p38 MAPK pathway. It is interesting that this active compound may be used as an effective agent to sensitize ovarian cancer to apoptosis induced by standard chemotherapies.

Propolis polyphenols: A review on the composition and anti-obesity mechanism of different types of propolis polyphenols.

Obesity, one of the most common nutritional diseases worldwide, can lead to dyslipidemia, high blood sugar, high blood pressure, and inflammation. Some drugs have been developed to ameliorate obesity. However, these drugs may cause serious side effects. Therefore, there is an urgent need for alternative "natural" remedies including propolis. Studies have found that propolis has excellent anti-obesity activity in in vitro and in vivo models during the past decades, of which polyphenols are the key component in regulating weight loss. This review focused on the different polyphenol compositions of propolis from different regions and plants, the evidence for the anti-obesity effects of different types of propolis and its derivatives, discussed the impact of propolis polyphenols on obesity related signal pathways, and proposed the molecular mechanism of how propolis polyphenols affect these signal pathways. For example, propolis and its derivatives regulate lipid metabolism related proteins, such as PPARα, PPARγ, SREBP-1&2, and HMG CoA etc., destroy the formation of CREB/CRTC2 transcription complex, activate Nrf2 pathway or inhibit protein kinase IKK ε/TBK1, thereby affecting fat production and lipid metabolism; The effects of propolis on adipokines (adiponectin, leptin and inflammatory factors) were discussed. Additionally, the mechanism of polyphenols in propolis promoting the browning of adipose tissues and the relationship between intestinal microorganisms was summarized. These information may be of value to better understand how specific propolis polyphenols interact with specific signaling pathways and help guide the development of new drugs to combat obesity and related metabolic diseases.

Echinochrome A Prevents Diabetic Nephropathy by Inhibiting the PKC-Iota Pathway and Enhancing Renal Mitochondrial Function in db/db Mice.

Echinochrome A (EchA) is a natural bioproduct extracted from sea urchins, and is an active component of the clinical drug, Histochrome®. EchA has antioxidant, anti-inflammatory, and antimicrobial effects. However, its effects on diabetic nephropathy (DN) remain poorly understood. In the present study, seven-week-old diabetic and obese db/db mice were injected with Histochrome (0.3 mL/kg/day; EchA equivalent of 3 mg/kg/day) intraperitoneally for 12 weeks, while db/db control mice and wild-type (WT) mice received an equal amount of sterile 0.9% saline. EchA improved glucose tolerance and reduced blood urea nitrogen (BUN) and serum creatinine levels but did not affect body weight. In addition, EchA decreased renal malondialdehyde (MDA) and lipid hydroperoxide levels, and increased ATP production. Histologically, EchA treatment ameliorated renal fibrosis. Mechanistically, EchA suppressed oxidative stress and fibrosis by inhibiting protein kinase C-iota (PKCι)/p38 mitogen-activated protein kinase (MAPK), downregulating p53 and c-Jun phosphorylation, attenuating NADPH oxidase 4 (NOX4), and transforming growth factor-beta 1 (TGFβ1) signaling. Moreover, EchA enhanced AMPK phosphorylation and nuclear factor erythroid-2-related factor 2 (NRF2)/heme oxygenase 1 (HO-1) signaling, improving mitochondrial function and antioxidant activity. Collectively, these findings demonstrate that EchA prevents DN by inhibiting PKCι/p38 MAPK and upregulating the AMPKα/NRF2/HO-1 signaling pathways in db/db mice, and may provide a therapeutic option for DN.

The Natural Stilbenoid (-)-Hopeaphenol Inhibits HIV Transcription by Targeting Both PKC and NF-κB Signaling and Cyclin-Dependent Kinase 9.

Despite effective combination antiretroviral therapy (cART), people living with HIV (PLWH) continue to harbor replication-competent and transcriptionally active virus in infected cells, which in turn can lead to ongoing viral antigen production, chronic inflammation, and increased risk of age-related comorbidities. To identify new agents that may inhibit postintegration HIV beyond cART, we screened a library of 512 pure compounds derived from natural products and identified (-)-hopeaphenol as an inhibitor of HIV postintegration transcription at low to submicromolar concentrations without cytotoxicity. Using a combination of global RNA sequencing, plasmid-based reporter assays, and enzyme activity studies, we document that hopeaphenol inhibits protein kinase C (PKC)- and downstream NF-κB-dependent HIV transcription as well as a subset of PKC-dependent T-cell activation markers, including interleukin-2 (IL-2) cytokine and CD25 and HLA-DRB1 RNA production. In contrast, it does not substantially inhibit the early PKC-mediated T-cell activation marker CD69 production of IL-6 or NF-κB signaling induced by tumor necrosis factor alpha (TNF-α). We further show that hopeaphenol can inhibit cyclin-dependent kinase 9 (CDK9) enzymatic activity required for HIV transcription. Finally, it inhibits HIV replication in peripheral blood mononuclear cells (PBMCs) infected in vitro and dampens viral reactivation in CD4+ cells from PLWH. Our study identifies hopeaphenol as a novel inhibitor that targets a subset of PKC-mediated T-cell activation pathways in addition to CDK9 to block HIV expression. Hopeaphenol-based therapies could complement current antiretroviral therapy otherwise not targeting cell-associated HIV RNA and residual antigen production in PLWH.

Statins inhibit protein kinase D (PKD) activation in intestinal cells and prevent PKD1-induced growth of murine enteroids.

We examined the impact of statins on protein kinase D (PKD) activation by G protein-coupled receptor (GPCR) agonists. Treatment of intestinal IEC-18 cells with cerivastatin inhibited PKD autophosphorylation at Ser916 induced by angiotensin II (ANG II) or vasopressin in a dose-dependent manner with half-maximal inhibition at 0.2 µM. Cerivastatin treatment inhibited PKD activation stimulated by these agonists for different times (5-60 min) and blunted HDAC5 phosphorylation, a substrate of PKD. Other lipophilic statins, including simvastatin, atorvastatin, and fluvastatin also prevented PKD activation in a dose-dependent manner. Using IEC-18 cell lines expressing PKD1 tagged with EGFP (enhanced green fluorescent protein), cerivastatin or simvastatin blocked GPCR-mediated PKD1-EGFP translocation to the plasma membrane and its subsequent nuclear accumulation. Similar results were obtained in IEC-18 cells expressing PKD3-EGFP. Mechanistically, statins inhibited agonist-dependent PKD activation rather than acting directly on PKD catalytic activity since exposure to cerivastatin or simvastatin did not impair PKD autophosphorylation or PKD1-EGFP membrane translocation in response to phorbol dibutyrate, which bypasses GPCRs and directly stimulates PKC and PKD. Furthermore, cerivastatin did not inhibit recombinant PKD activity determined via an in vitro kinase assay. Using enteroids generated from intestinal crypt-derived epithelial cells from PKD1 transgenic mice as a model of intestinal regeneration, we show that statins oppose PKD1-mediated increase in enteroid area, complexity (number of crypt-like buds), and DNA synthesis. Our results revealed a previously unappreciated inhibitory effect of statins on receptor-mediated PKD activation and in opposing the growth-promoting effects of PKD1 on intestinal epithelial cells.

Melatonin increases susceptibility to atrial fibrillation in obesity via Akt signaling impairment in response to lipid overload.

Melatonin has been proven to have antiarrhythmic potential; however, several studies have recently challenged this view. Herein, using a mouse model of obesity-induced atrial fibrillation (AF), we tentatively explored whether exogenous melatonin supplementation could increase AF susceptibility in the context of obesity. We observed that an 8-week drinking administration of melatonin (60 µg/ml in water) induced a greater susceptibility to AF in obese mice, although obesity-induced structural remodeling was alleviated. An investigation of systemic insulin sensitivity showed that melatonin treatment improved insulin sensitivity in obese mice, whereas it inhibited glucose-stimulated insulin secretion. Notably, melatonin treatment inhibited protein kinase B (Akt) signaling in the atria of obese mice and palmitate-treated neonatal rat cardiomyocytes, thereby providing an AF substrate. Melatonin increased lipid stress in obesity, as evidenced by elevated lipid accumulation and lipolysis-related gene expression, thus contributing to the impairment in atrial Akt signaling. Taken together, our results demonstrated that melatonin could increase AF susceptibility in obesity, probably due to increased lipid stress and resultant impairment of atrial Akt signaling. Our findings suggest that special precautions should be taken when administering melatonin to obese subjects.