PKCα Protein Research Articles

ICA1 affects APP processing through the PICK1-PKCα signaling pathway.

Islet cell autoantigen 1 (ICA1) is involved in autoimmune diseases and may affect synaptic plasticity as a neurotransmitter. Databases related to Alzheimer's disease (AD) have shown decreased ICA1 expression in patients with AD. However, the role of ICA1 in AD remains unclear. Here, we report that ICA1 expression is decreased in the brains of patients with AD and an AD mouse model. The ICA1 increased the expression of amyloid precursor protein (APP), disintegrin and metalloprotease 10 (ADAM10), and disintegrin and metalloprotease 17 (ADAM17), but did not affect protein half-life or mRNA levels. Transcriptome sequencing analysis showed that ICA1 regulates the G protein-coupled receptor signaling pathway. The overexpression of ICA1 increased PKCα protein levels and phosphorylation. Our results demonstrated that ICA1 shifts APP processing to non-amyloid pathways by regulating the PICK1-PKCα signaling pathway. Thus, this study suggests that ICA1 is a novel target for the treatment of AD.

Mechanism of Hirudin-Mediated Inhibition of Proliferation in Ovarian Cancer Cells.

To investigate the inhibitory effect of hirudin on the cell proliferation of human ovarian cancer A2780 cells by preventing thrombin and its underlying molecular mechanism. Cell Counting Kit-8 (CCK-8) method was used to detect the effect of different concentrations of hirudin and thrombin on the cell proliferation of A2780 cells. PAR-1 wild-type overexpression plasmid was constructed utilizing enzyme digestion identification, and it was transferred to A2780 cells. Sequencing and Western blot were used to detect the changes in PAR-1 protein expression. Western blot detection of PKCα protein phosphorylation in A2780 cells was performed. We also implemented quantitative PCR to detect the mRNA expression levels of epithelial-mesenchymal transition (EMT)-related genes, CDH2, Snail, and Vimentin, in A2780 cells. 1μg/ml hirudin treatment maximally inhibited the promotion of A2780 cell proliferation by thrombin. Hirudin inhibited the binding of thrombin to the N-terminus of PAR-1, hindered PKCα protein phosphorylation in A2780 cells, and downregulated the mRNA expression levels of CDH2, Snail, and Vimentin. In conclusion, hirudin inhibits the cell proliferation of ovarian cancer A2780 cells, and the underlying mechanism may be through downregulating the transcription level of EMT genes, CDH2, Snail, and Vimentin. This study indicates that hirudin may have a therapeutic potential as an anti-cancer agent for ovarian cancer.

Proteomics-based screening of AKR1B1 as a therapeutic target and validation study for sepsis-associated acute kidney injury.

Sepsis and sepsis-associated acute kidney injury (SA-AKI) pose significant global health challenges, necessitating the development of innovative therapeutic strategies. Dysregulated protein expression has been implicated in the initiation and progression of sepsis and SA-AKI. Identifying potential protein targets and modulating their expression is crucial for exploring alternative therapies. We established an SA-AKI rat model using cecum ligation perforation (CLP) and employed differential proteomic techniques to identify protein expression variations in kidney tissues. Aldose reductase (AKR1B1) emerged as a promising target. The SA-AKI rat model received treatment with the aldose reductase inhibitor (ARI), epalrestat. Blood urea nitrogen (BUN) and creatinine (CRE) levels, as well as IL-1β, IL-6 and TNF-α levels in the serum and kidney tissues, were monitored. Hematoxylin-eosin (H-E) staining and a pathological damage scoring scale assessed renal tissue damage, while protein blotting determined PKC (protein kinase C)/NF-κB pathway protein expression. Differential proteomics revealed significant downregulation of seven proteins and upregulation of 17 proteins in the SA-AKI rat model renal tissues. AKR1B1 protein expression was notably elevated, confirmed by Western blot. ARI prophylactic administration and ARI treatment groups exhibited reduced renal injury, low BUN and CRE levels and decreased IL-1β, IL-6 and TNF-α levels compared to the CLP group. These changes were statistically significant (P<0.05). AKR1B1, PKC-α, and NF-κB protein expression levels were also lowered in the ARI prophylactic administration and ARI treatment groups compared to the CLP group (P<0.05). Epalrestat appeared to inhibit the PKC/NF-κB inflammatory pathway by inhibiting AKR1B1, resulting in reduced inflammatory cytokine levels in renal tissues and blood. This mitigated renal tissue injuries and improved the systemic inflammatory response in the severe sepsis rat model. Consequently, AKR1B1 holds promise as a target for treating sepsis-associated acute kidney injuries.

Lead-induced cardiomyocytes apoptosis by inhibiting gap junction intercellular communication via modulating the PKCα/Cx43 signaling pathway

ObjectiveThe aim of this study was to investigate the regulatory mechanism of Pb regulates gap junction intercellular communication to induced apoptosis in H9c2 cells. MethodsH9c2 cell line is used as the research object in this study, and treated with different concentrations of Pb acetate. Subsequently, Cell viability was measured by the Cell Counting Kit-8 (CCK-8) assay. The levels of lactate dehydrogenase (LDH), aspartate transaminase (AST) and creatine kinase-MB (CK-MB) in the supernatants were measured using respective commercial enzyme-linked immune sorbent assay (ELISA) kits. Western blot was used to detect the expression of apoptosis-related protein in H9c2 cells in each group. Quantitative RT-PCR Analysis Total RNA was extracted from frozen H9c2 cells using Trizol reagent, the PKCα and Cx43 in the supernatant of H9c2 cells was determined by the BCA protein detection kit. ResultsH9c2 cells increased release of cardiac enzymes (LDH, AST, and CK-MB) and decreased cell survival rate, and the Cx43, p-Cx43, PKCα and p-PKCα protein levels showed a dose-dependent decrease after Pb treatment. PKCα was activated with PMA, the relative expression level of Cx43 protein increased significantly, the expression of Bcl-2 increased and Bax and Cyt-c decreased compared with Pb exposure group, and the myocardial enzymes (LDH, AST, and CK-MB) in cell culture supernatant decreased compared with Pb exposure group, indicating that the degree of cell damage was alleviated. Results showed that Pb inhibited PKCα activity, decreased the expression of total Cx43 and P-Cx43 protein, and aggravated myocardial injury. ConclusionsPb decrease gap junction intercellular communication, which induce apoptosis in H9c2 cells by inhibiting the PKCα/Cx43 signaling pathway.

Distinct protein kinase C isoforms drive the cell cycle re-entry of two separate populations of neonatal rat ventricular cardiomyocytes.

The present study tested the hypothesis that protein kinase C-α (PKC-α) recruitment in the presence of the p38α/β MAPK inhibitor SB203580 facilitated the appearance and cell cycle re-entry of nestin(+)-neonatal rat ventricular cardiomyocytes (NNVMs) and induced a transcript profile delineating a proliferative phenotype. Phorbol 12,13-dibutyrate (PDBu) treatment did not induce de novo nestin expression or increase the cell cycle re-entry of 1-day-old NNVMs but significantly increased runt-related transcription factor 1 (Runx1) and p16 cell cycle inhibitor (CDKN2a) mRNA levels and downregulated epithelial cell transforming 2 (ECT2) mRNA expression. SB203580 administration to PDBu-treated NNVMs induced de novo nestin expression, preferentially increased the density (normalized to 500 NNVMs) of nestin(+)-NNVMs that incorporated 5-bromo-2'-deoxyuridine (PDBu, 1.4 ± 3 vs. PDBu/SB203580, 128 ± 34; n = 5 independent litters), significantly inhibited CDKN2a and Runx1 mRNA upregulation and reversed ECT2 mRNA downregulation. PDBu treatment of NNVMs reduced PKC-α, protein kinase-δ (PKC-δ) and protein kinase-ε (PKC-ε) protein levels and GF109203X (conventional PKC isoform inhibitor) selectively attenuated PKC-α protein downregulation. GF109203X administration to PDBu/SB203580-treated NNVMs significantly reduced the density of nestin(+)-NNVMs that incorporated 5-bromo-2'-deoxyuridine (PDBu/SB203580/GF109203X, 40 ± 46; n = 5). Moreover, GF109203X/PDBu/SB203580 treatment unmasked the predominant appearance of a separate NNVM population that incorporated 5-bromo-2'-deoxyuridine (PDBu/SB203580/GF109203X, 192 ± 42; n = 5) delineated by the absence of de novo nestin expression. Sotrastaurin (conventional/novel PKC isoform inhibitor) administration to PDBu/SB203580-treated NNVMs significantly attenuated the density of nestin(+)-NNVMs (PDBu/SB203580/sotrastaurin, 8 ± 10; n = 4) and nestin(-)-NNVMs (PDBu/SB203580/sotrastaurin, 64 ± 30; n = 4) that incorporated 5-bromo-2'-deoxyuridine. These data reveal that the neonatal rat heart contains at least two separate populations of NNVMs that re-enter the cell cycle and the preferential appearance of nestin(+)- or nestin(-)-NNVMs is driven by distinct PKC isoforms in the presence of SB203580.NEW & NOTEWORTHY The appearance of nestin(+)-neonatal rat ventricular cardiomyocytes that re-entered the cell cycle following phorbol ester stimulation in the presence of p38α/β MAPK inhibitor SB203580 was associated with the inhibition of Runx1 and CDKN2a mRNA upregulation. PKC-α selectively induced the cell cycle re-entry of nestin(+)-neonatal rat ventricular cardiomyocytes. Pharmacological inhibition of PKC-α with concomitant p38α/β MAPK suppression unmasked the cell cycle re-entry of a second population of neonatal rat ventricular cardiomyocytes in the absence of nestin expression.

Sphingosine 1-phosphate receptor 2 promotes the onset and progression of non-alcoholic fatty liver disease-related hepatocellular carcinoma through the PI3K/AKT/mTOR pathway

PurposeRecent studies have revealed an increase in the incidence rate of non-alcoholic fatty liver disease-related hepatocellular carcinoma (NAFLD-HCC). Furthermore, the association of Sphingosine 1-phosphate receptor 2 (S1PR2) with various types of tumours is identified, and the metabolism of conjugated bile acids (CBAs) performs an essential function in the onset and development of HCC. However, the association of CBA and S1PR2 with NAFLD-HCC is unclear.MethodsThe relationship between the expression of S1PR2 and the prognosis of patients suffering from NAFLD-HCC was investigated by bioinformatics techniques. Subsequently, the relationship between S1PR2 and the biological behaviours of HCC cell lines Huh 7 and HepG2 was explored by conducting molecular biology assays. Additionally, several in vivo animal experiments were carried out for the elucidation of the biological impacts of S1PR2 inhibitors on HCC cells. Finally, We used Glycodeoxycholic acid (GCDA) of CBA to explore the biological effects of CBA on HCC cell and its potential mechanism.ResultsHigh S1PR2 expression was linked to poor prognosis of the NAFLD-HCC patients. According to cellular assay results, S1PR2 expression could affect the proliferation, invasion, migration, and apoptosis of Huh 7 and HepG2 cells, and was closely associated with the G1/G2 phase of the cell cycle. The experiments conducted in the In vivo conditions revealed that the overexpression of S1PR2 accelerated the growth of subcutaneous tumours. In addition, JTE-013, an antagonist of S1PR2, effectively inhibited the migration and proliferation of HCC cells. Furthermore, the bioinformatics analysis highlighted a correlation between S1PR2 and the PI3K/AKT/mTOR pathway.GCDA administration further enhanced the expression levels of p-AKT, p-mTOR, VEGF, SGK1, and PKCα. Moreover, both the presence and absence of GCDA did not reveal any significant change in the levels of S1PR2, p-AKT, p-mTOR, VEGF, SGK1, and PKCα proteins under S1PR2 knockdown, indicating that CBA may regulates the PI3K/AKT/mTOR pathway by mediating S1PR2 expression.ConclusionS1PR2 is a potential prognostic biomarker in NAFLD-HCC. In addition, We used GCDA in CBAs to treat HCC cell and found that the expression of S1PR2 was significantly increased, and the expression of PI3K/AKT/mTOR signalling pathway-related signal molecules was also significantly enhanced, indicating that GCDA may activate PI3K/AKT/mTOR signalling pathway by up-regulating the expression of S1PR2, and finally affect the activity of hepatocellular carcinoma cells. S1PR2 can be a candidate therapeutic target for NAFLD-HCC. Collectively, the findings of this research offer novel perspectives on the prevention and treatment of NAFLD-HCC.

Novel Smooth Muscle Ca2+-Signaling Nanodomains in Blood Pressure Regulation.

Ca2+ signals in smooth muscle cells (SMCs) contribute to vascular resistance and control blood pressure. Increased vascular resistance in hypertension has been attributed to impaired SMC Ca2+ signaling mechanisms. In this regard, transient receptor potential vanilloid 4 (TRPV4SMC) ion channels are a crucial Ca2+ entry pathway in SMCs. However, their role in blood pressure regulation has not been identified. We used SMC-specific TRPV4-/- (TRPV4SMC-/-) mice to assess the role of TRPV4SMC channels in blood pressure regulation. We determined the contribution of TRPV4SMC channels to the constrictor effect of α1 adrenergic receptor (α1AR) stimulation and elevated intraluminal pressure: 2 main physiologic stimuli that constrict resistance-sized arteries. The contribution of spatially separated TRPV4SMC channel subpopulations to elevated blood pressure in hypertension was evaluated in angiotensin II-infused mice and patients with hypertension. We provide first evidence that TRPV4SMC channel activity elevates resting blood pressure in normal mice. α1AR stimulation activated TRPV4SMC channels through PKCα (protein kinase Cα) signaling, which contributed significantly to vasoconstriction and blood pressure elevation. Intraluminal pressure-induced TRPV4SMC channel activity opposed vasoconstriction through activation of Ca2+-sensitive K+ (BK) channels, indicating functionally opposite pools of TRPV4SMC channels. Superresolution imaging of SMCs revealed spatially separated α1AR:TRPV4 and TRPV4:BK nanodomains in SMCs. These data suggest that spatially separated α1AR-TRPV4SMC and intraluminal pressure-TRPV4SMC-BK channel signaling have opposite effects on blood pressure, with α1AR-TRPV4SMC signaling dominating under resting conditions. Furthermore, in patients with hypertension and a mouse model of hypertension, constrictor α1AR-PKCα-TRPV4 signaling was upregulated, whereas dilator pressure-TRPV4-BK channel signaling was disrupted, thereby increasing vasoconstriction and elevating blood pressure. Our data identify novel smooth muscle Ca2+-signaling nanodomains that regulate blood pressure and demonstrate their impairment in hypertension.

Activation of the GABA-alpha receptor by berberine rescues retinal ganglion cells to attenuate experimental diabetic retinopathy

PurposeThe aim of this study was to investigate the role and mechanism of berberine (BBR) in the protection of injured retinal ganglion cells (RGCs) in diabetic retinopathy (DR).MethodsExperimental diabetic retinopathy rat model was successfully induced by a single intraperitoneal injection of streptozotocin (STZ, 60 mg/kg) in male SD rats with sufficient food and water for 8 weeks. Animals were randomly divided into four groups: (1) non-diabetic, (2) diabetic, (3) diabetic + BBR + PBS, and (4) diabetic + BBR + SR95531. BBR (100 mg/kg) was given daily by gavage to rats in the group (3) and group (4) for 8 weeks, and weekly intravitreal injections were conducted to rats in the group (3) with 5 μL of 1×PBS and rats in the group (4) with 5 μL of GABA-alpha receptor antagonist SR95531 to investigate the underlying mechanisms. The survival and apoptosis of RGCs were observed by fluorescence gold labeling technology and TUNEL staining. Visual function was evaluated by visual electrophysiological examination. Western blotting and immunofluorescence staining were used to analyze the expression of GABA-alpha receptors in RGCs.ResultsIn an animal model, BBR can increase the survival of RGCs, reduce RGCs apoptosis, and significantly improve the visual function. The reduction of GABA, PKC-α, and Bcl-2 protein expression caused by DR can be considerably increased by BBR. SR95531 inhibits BBR's protective effect on RGC and visual function, as well as its upregulation of PKC-α and Bcl-2.ConclusionBBR is a promising preventive or adjuvant treatment for DR complications, and its key protective effect may involve the regulation of RGC apoptosis through the GABA-alpha receptor/protein kinase C-alpha (GABAAR/PKC-α) pathway.

Effective components and mechanism analysis of anti-platelet aggregation effect of Justicia procumbens L.

Ethnopharmacological relevanceJusticia procumbens L. is a traditional Chinese medicine, first recorded in "Shen Nong's Herbal Classic", for the treatment of lumbar pain and fever. As a widely distributed herb, it has also been documented in India, Nepal, and Malaysia. In “Tang Materia Medica”, a famous medicinal book of Tang Dynasty in ancient China, it was first used to treat diseases associated with blood stasis. Blood stasis syndrome is closely related to thrombus formation and platelet aggregation. Although some compounds isolated from this plant have anti-platelet aggregation effects, the main chemical components and mechanism of J. procumbens in terms of these effects are little known. Aims of the studyThrough in vivo and in vitro experiments, this studsy revealed the characteristic components and action mechanism of anti-platelet aggregation by J. procumbens from an overall perspective. Materials and methodsThe effective crude extracts of the whole plant were screened via an in vitro anti-platelet aggregation test. After incubating these extracts with apheresis platelets, high affinity compounds were detected by HPLC-MS and regulatory genes were detected using gene chips. The effective components and potential target proteins were analyzed using computational docking technology. Furthermore, the compound with the strongest predicted activity was evaluated in vivo via an anti-thrombotic test. ResultsIntegrin aⅡbβ3, PKCα, PI3Kγ, and mitogen-activated protein kinase 14 were found to be potential targets. Justicidin B, tuberculatin, chinensinaphthol methyl ether, and neojusticin B were effective compounds that inhibited human platelet aggregation by suppressing Gq-PLC-PKC and Gi-PI3K-MAPK signaling pathways. Among the compounds that bind to platelets, justicidin B showed the strongest virtual binding force. The test of carotid artery thrombosis induced by ferric chloride in SD rats confirmed that justicidin B inhibited thrombus formation. ConclusionExperimental investigation showed that arylnaphthalene lignan aglycones with one methylenedioxy group and two methoxy groups are effective components for anti-platelet aggregation by J. procumbens. These compounds inhibit Gq-PLC-PKC and Gi-PI3K-MAPK signaling pathways by suppressing the expression of genes such as ITGB3, PRKCA, PIK3CG, and MAPK14. These results reflected the characteristics of multi-component and multi-target synergistic treatment of Chinese medicine.

A high-concentrate diet provokes inflammation, endoplasmic reticulum stress, and apoptosis in mammary tissue of dairy cows through the upregulation of STIM1/ORAI1

High-concentrate feeding can induce subacute ruminal acidosis, which leads to mammary tissue injury in dairy cows. Therefore, the purpose of this research was to evaluate the effect of high-concentrate feeding on STIM1 (stromal interaction molecule 1)/ORAI1 (Orai calcium release-activated calcium modulator 1)-mediated inflammation, endoplasmic reticulum stress (ERS), and apoptosis in the mammary tissue of dairy cows. A total of 12 healthy mid-lactating Holstein cows of similar weight were randomly allotted into the following 2 groups: a high-concentrate (HC) group (concentrate:forage = 6:4) and a low-concentrate (LC) group (concentrate:forage = 4:6). The trial lasted for 3 wk. After the feeding experiment, rumen fluid, lacteal vein blood, and mammary tissue samples were collected. The results showed that the HC diet significantly increased blood lipopolysaccharide levels, decreased ruminal pH, and upregulated the concentrations of Ca2+ and proinflammatory cytokines, including TNF-α, IL-1β, and IL-6, and the enzyme activities of caspase-3, caspase-9, PKC, and IKK. The upregulation of STIM1, ORAI1, PKCα, IKKβ, phosphorylated-IκBα, phosphorylated-p65, TNF-α, and IL-1α proteins in the HC group indicated activation of the STIM1/ORAI1-mediated inflammatory signaling pathway compared with that in the LC group. The HC diet also induced ERS by increasing the mRNA and protein abundances of GRP78, CHOP, PERK, ATF6, and IRE1α in the mammary tissue. Compared with the LC group, the mRNA expression levels and protein abundances of caspase-3, cleaved caspase-3, caspase-9, and BAX were markedly increased in the HC group. However, the mRNA and protein expression levels of Bcl-2 were significantly decreased in the HC group. Therefore, this study demonstrated that the HC diet can activate the store-operated calcium entry channel by upregulating the expression of STIM1 and ORAI1 and induce inflammation, ERS, and apoptosis in the mammary tissue of dairy cows.

Autophagy and Apoptosis Induced in U87 MG Glioblastoma Cells by Hypericin-Mediated Photodynamic Therapy Can Be Photobiomodulated with 808 nm Light

Glioblastoma is one of the most aggressive types of tumors. Although few treatment options are currently available, new modalities are needed to improve prognosis. In this context, photodynamic therapy (PDT) is a promising adjuvant treatment modality. In the present work, hypericin-mediated PDT (hypericin-PDT, 2 J/cm2) of U87 MG cells is combined with (2 min, 15 mW/cm2 at 808 nm) photobiomodulation (PBM). We observed that PBM stimulates autophagy, which, in combination with PDT, increases the treatment efficacy and leads to apoptosis. Confocal fluorescence microscopy, cytotoxicity assays and Western blot were used to monitor apoptotic and autophagic processes in these cells. Destabilization of lysosomes, mitochondria and the Golgi apparatus led to an increase in lactate dehydrogenase activity, oxidative stress levels, LC3-II, and caspase-3, as well as a decrease of the PKCα and STAT3 protein levels in response to hypericin-PDT subcellular concentration in U87 MG cells. Our results indicate that therapeutic hypericin concentrations can be reduced when PDT is combined with PBM. This will likely allow to reduce the damage induced in surrounding healthy tissues when PBM-hypericin-PDT is used for in vivo tumor treatments.

Effects of formula composed of active monomers of removing heat and phlegm prescription on malignant phenotypes and growth signaling in esophageal carcinoma cells.

e16051 Background: Esophageal carcinoma (EC) ranks seventh in the incidence of malignant tumors and the sixth mortality worldwide. Removing heat and phlegm prescription(RHPP, composed of Rhizoma Dioscoreae Nipponicae, Rhizoma Paridis, Saponin, Rhizoma Bolbostemmae) was an effective formula screened from 531 Chinese herbs for treating EC in our previous study. The purpose of this study is to further track, isolate, purify and identify the active monomers of RHPP, study the effect of each active monomer on Eca109, EC9706, EC-1, TE-1 four EC cells and the signaling mechanism, then optimize and compose new active monomers formula and study its mechanism on EC cells. Methods: The active monomer of RHPP was extracted, separated and identified by ethanol extractioncolumn, chromatography, recrystallization, HPLC, spectroscopic method,etc. The effects of four kinds of active monomers and their composed formula on the proliferation, migration, clone formation, cell cycle and signal pathway proteins expression of Eca109 cell, EC9706 cell and TE-1 cell were investigated by MTT assay, RTCA assay, soft agar assay, flow cytometry and western blot analysis. Results: Four active monomers were identified from Rhizoma Dioscoreae Nipponicae (CSL), Saponin (ZJ), Rhizoma Bolbostemmae (TBM), Rhizoma Paridis (CL) respectively with molecular weights of 868, 1003, 1365, 854.5, and corresponding molecular formulas of C45H72O16, C50H82O20, C64H100O31 and C44H70O16(China patient No. ZL202010136431.6). Four active monomers significantly affected the cell morphology, proliferation, migration, cloning ability, cell cycle of four EC cells. The IC50 values of the active monomer of CSL, ZJ, TBM and CL for Eca109 were 1.29±0.12, 2.42±0.09, 1.93±0.09, 3.04±0.28μg/ml respectively; for EC9706 were 1.41±0.02, 5.94±0.45, 1.97±0.09, 0.63±0.04μg/ml respectively; for TE-1 were 3.72±0.28, 35.58±0.58, 7.90±0.41, 1.85±0.09μg/ml respectively; for EC-1 were 1.11±0.14, 3.56±0.28, 1.23±0.02, 0.61±0.02μg/ml respectively. Four active monomers could downregulate EGFR, PLC-γ1, and PKCα protein expression. Using the baseline proportional increase and decrease design method to compose new removing heat prescription(RH), removing phlegm prescription(RP) and removing heat and phlegm prescription (RHPP), the ratio of each drug monomer in RH, RP and RHPP were mCSL: mCL = 6: 4, mZJ: mTBM = 3: 7, mCSL: mCL: mZJ: mTBM = 48: 32: 6: 14. RH, RP and RHPP all could inhibit the proliferation, migration, cloning ability, cell cycle of four EC cells. Conclusions: The four active monomers and new composed RHPP all can inhibit the proliferation of EC9706, Eca109, TE-1, EC-1 four EC cells, which have close relationship with EGFR, PLC-γ1, and PKCαproteins expression. This study provides new formula and basis for the development of anti-esophageal carcinoma drugs in traditional Chinese medicine.

Epigenetic Modification Suppresses PKCα Expression in Epithelial Cancers

Members of the protein kinase C (PKC) family of serine/threonine kinases are key mediators of signaling pathways that are altered in cancer. The conventional PKC, PKCα, has anti-proliferative and tumor-suppressive roles in many epithelial systems. Consistent with these roles, PKCα expression is reduced in about 60% of colorectal and endometrial cancers. The importance of PKCα loss in these tumors is highlighted by findings that (a) low levels of PKCα expression correlate with poor survival in patients, and b) PKCα deficiency enhances tumor aggressiveness in mouse models of intestinal and uterine cancer. The objective of this study was to understand the mechanisms involved in the loss of PKCα in tumors and to explore strategies for restoration of PKCα expression for cancer treatment. Our analysis of cell lines and patient samples has determined that loss of PKCα is the result of reduced PRKCA transcription. However, no differences in the activity of individual promoter elements were observed between PKCαhigh and PKCαlow cell lines, pointing to an epigenetic effect. Thus, we hypothesized that PKCα loss in colon and endometrial cancers is caused by changes in DNA methylation of the PRKCA promoter region and that clinically relevant demethylation agents offer a strategy for therapeutic re-expression of this tumor suppressive kinase. MBDCap-seq analysis of endometrial tumors and normal controls revealed tumor-associated de novo hypermethylation in the right CpG shore of PRKCA, with no consistent changes in the PRKCA promoter or left shore. Bisulfite treatment and pyrosequencing analysis of 27 colon and endometrial cancer cell lines revealed different methylation levels of the PRKCA right CpG shore that inversely correlated with PKCα mRNA and protein expression. The methylation pattern in the PRKCA promoter region as well as the inverse correlation between right shore methylation and PKCα mRNA expression were confirmed in colon cancer samples. Treatment of PKCαlow endometrial and colon cancer cells with the FDA approved de-methylating agent, 5-aza-2′-deoxycytidine (decitabine, Dacogen®), significantly reduced the methylation of the PRKCA right CpG shore and increased PKCα expression. Ongoing studies in PtenΔ4-5/+ mice, which develop endometrial lesions lacking PKCα expression, will determine if decitabine can restore PKCα expression in endometrial tumors in vivo. In conclusion, the tumor suppressive protein kinase, PKCα, is transcriptionally repressed by hypermethylation of the right CpG shore of the PRKCA promoter region in colon and endometrial cancers, and the expression of PKCα can be restored by treatment with a clinically relevant, FDA approved de-methylation agent.

Simulated vehicle exhaust exposure induces sex-dependent behavioral deficits in rats

Chronic exposure to vehicle exhaust emissions are known to cause several adverse health effects. In this study, we examined the impact of several parameters of behavioral, cardiovascular and biochemical functions upon exposure of pro-oxidants CO2, NO2 and CO (simulated vehicle exhaust exposure: SVEE) in male and female rats. Adult rats were subjected to SVEE or ambient air in whole body chambers (5 h/day, 2 weeks). Male, but not female, rats developed memory deficits, and exhibited anxiety- and depression-like behavior, accompanied with significantly high levels of serum corticosterone, oxidative stress, and inflammatory markers (CRP and TNFα), associated with lower levels of total antioxidant capacity, glutathione, glyoxalase and superoxide dismutase (SOD) activities. Brain region-specific downregulation of Cu/Zn SOD, Mn SOD, GSR, PKCα, ERK1/2, CaMKIV, CREB, BDNF and NMDAR subunit protein expression were also observed in male, but not female, rats. Blood pressure, heart rate and eGFR were not negatively impacted by SVEE. Our results suggest that SVEE, through its pro-oxidant content, induces oxido-inflammation in susceptible brain regions in a sex-dependent manner.

The AXL-PYK2-PKCα axis as a nexus of stemness circuits in TNBC.

Cancer stem cells (CSCs) are implicated in tumor initiation, metastasis and drug resistance, and considered as attractive targets for cancer therapy. Here we identified a clinically relevant signaling nexus mediated by AXL receptor, PYK2 and PKCα and show its impact on stemness in TNBC. AXL, PYK2, and PKCα expression correlates with stemness signature in basal-like breast cancer patients, and their depletion in multiple mesenchymal TNBC cell lines markedly reduced the number of mammosphere-forming cells and cells harboring CSCs characteristic markers. Knockdown of PYK2 reduced the levels of AXL, PKCα, FRA1, and PYK2 proteins, and similar trend was obtained upon PKCα depletion. PYK2 depletion decreased AXL transcription through feedback loops mediated by FRA1 and TAZ, whereas PKCα inhibition induced redistribution of AXL to endosomal/lysosomal compartment and enhanced its degradation. PYK2 and PKCα cooperate at a convergence point of multiple stemness-inducing pathways to regulate AXL levels and concomitantly the levels/activation of STAT3, TAZ, FRA1, and SMAD3 as well as the pluripotent transcription factors Nanog and Oct4. Induction of stemness in TNBC sensitized cells to PYK2 and PKCα inhibition suggesting that targeting the AXL-PYK2-PKCα circuit could be an efficient strategy to eliminate CSCs in TNBC.

AhR/miR-23a-3p/PKCα axis contributes to memory deficits in ovariectomized and normal aging female mice

The mechanism of estrogen deficiency-induced cognitive impairment is still not fully elucidated. In this study, we assessed the effect of microRNA (miRNA) on the memory of long-term estrogen-deficient mice after ovariectomy (OVX) and normal aging. We observed that 5-month OVX and 22-month-old normal aging female mice showed significantly impaired spatial and object recognition memory, declined hippocampal long-term potentiation (LTP), and decreased hippocampal protein kinase C α (PKCα) protein. Quantitative real-time PCR analysis showed upregulated miRNA-23a-3p (miR-23a-3p) in the hippocampus of 5-month OVX and 22-month-old female mice. In vitro, overexpression of miR-23a-3p downregulated PKCα by binding the 3¢ UTRs of Prkca mRNAs, which was prevented by its antisense oligonucleotide AMO-23a. In vivo, adeno-associated virus-mediated overexpression of miR-23a-3p (AAV-pre-miR-23a-3p) suppressed hippocampal PKCα and impaired the memory of mice. Chromatin immunoprecipitation analysis showed that aryl hydrocarbon receptor (AhR) binds the promoter region of miR-23a-3p. The AhR-dependent downregulation of PKCα could be prevented by AMO-23a as well. Furthermore, knockdown of miR-23a-3p using AAV-AMO-23a rescued the cognitive and electrophysiological impairments of OVX and normal aging female mice. We conclude that long-term estrogen deficiency impairs cognition and hippocampal LTP by activating the AhR/miR-23a-3p/PKCα axis. The knockdown of miR-23a-3p may be a potentially valuable therapeutic strategy for estrogen deficiency-induced memory deficits.

Normal spontaneous firing of cardiac pacemaker cells is regulated by basal pkc delta activation

Abstract The spontaneous beating rate of rabbit sinoatrial node cells (SANC) is regulated by local subsarcolemmal calcium releases (LCRs) from sarcoplasmic reticulum (SR). LCRs appear during diastolic depolarization (DD) and activate an inward sodium/calcium exchange current which increases DD rate and thus accelerates spontaneous SANC firing. High basal level of protein kinase A and calcium/calmodulin-dependent protein kinase II phosphorylation are required to sustain basal LCRs and normal spontaneous SANC firing. Recently we discovered that basal PKC activation is also obligatory for cardiac pacemaker function: inhibition of PKC activity by broad spectrum PKC inhibitors Bis I or calphostin C markedly suppressed SR calcium cycling and decreased or abolished spontaneous beating of freshly isolated rabbit SANC. Here we studied which PKC isoforms mediate PKC-dependent effects on cardiac pacemaker cell automaticity. The PKC superfamily consists of 3 major subgroups: conventional, novel and atypical. All PKC isoforms were detected at the RNA level (RT-qPCR) in the rabbit SA node and ventricle, and expression levels were comparable in both tissues. Expression of PKCβ, however, was markedly higher in the rabbit SA node, compared to other PKC isoenzymes in either tissue. We verified expression of conventional PKC (α, β) and novel PKC-delta at the protein level in SANC and ventricular myocytes (VM). Western blot confirmed RNA results, showing a 6-fold higher PKCβ protein abundance in SANC compared to VM. Expression of PKCα protein was similar in both cell types, while PKC-delta protein was more abundant in VM. To study whether PKCβ regulates spontaneous beating of SANC we employed selective inhibitor of conventional (α, β, gamma) PKC isoforms Go6976 (10 μmol/L), which had no effects on either LCR characteristics (confocal microscopy, calcium indicator Fluo-3AM) or spontaneous beating of freshly isolated rabbit SANC (perforated patch-clamp technique). Because selective PKC-delta inhibitors are not available, we explored effects of PKC-delta inhibition comparing effects of Go6976 (the inhibitor of conventional PKCs) and Go6983, which inhibits conventional PKCs and PKC-delta. In contrast to Go6976, Go6983 (5 μmol/L) markedly decreased the LCR size (from 7.1±0.4 to 4.5±0.3 μm) and number per each spontaneous cycle (from 1.3±0.1 to 0.8±0.1). It also markedly increased the LCR period (time from the prior AP-induced calcium transient to the subsequent LCR) which was paralleled by an increase in the spontaneous SANC cycle length. Rottlerin, another PKC-delta inhibitor, produced similar effects on LCR characteristics, and markedly and time-dependently decreased DD rate, leading to an increase in the spontaneous cycle length, and finally abrogated the spontaneous SANC firing. Thus, our data indicate that basal activity of PKC-delta, but not that of PKCβ, is essential for generation of LCRs and normal spontaneous firing of cardiac pacemaker cells. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): Intramural Research Program, National Institute on Aging, National Institute of Health, USA

Defining an Upstream VEGF (Vascular Endothelial Growth Factor) Priming Signature for Downstream Factor-Induced Endothelial Cell-Pericyte Tube Network Coassembly.

In this work, we have sought to define growth factor requirements and the signaling basis for different stages of human vascular morphogenesis and maturation. Approach and Results: Using a serum-free model of endothelial cell (EC) tube morphogenesis in 3-dimensional collagen matrices that depends on a 5 growth factor combination, SCF (stem cell factor), IL (interleukin)-3, SDF (stromal-derived factor)-1α, FGF (fibroblast growth factor)-2, and insulin (factors), we demonstrate that VEGF (vascular endothelial growth factor) pretreatment of ECs for 8 hours (ie, VEGF priming) leads to marked increases in the EC response to the factors which includes; EC tip cells, EC tubulogenesis, pericyte recruitment and proliferation, and basement membrane deposition. VEGF priming requires VEGFR2, and the effect of VEGFR2 is selective to the priming response and does not affect factor-dependent tubulogenesis in the absence of priming. Key molecule and signaling requirements for VEGF priming include RhoA, Rock1 (Rho-kinase), PKCα (protein kinase C α), and PKD2 (protein kinase D2). siRNA suppression or pharmacological blockade of these molecules and signaling pathways interfere with the ability of VEGF to act as an upstream primer of downstream factor-dependent EC tube formation as well as pericyte recruitment. VEGF priming was also associated with the formation of actin stress fibers, activation of focal adhesion components, upregulation of the EC factor receptors, c-Kit, IL-3Rα, and CXCR4 (C-X-C chemokine receptor type 4), and upregulation of EC-derived PDGF (platelet-derived growth factor)-BB, PDGF-DD, and HB-EGF (heparin-binding epidermal growth factor) which collectively affect pericyte recruitment and proliferation. Overall, this study defines a signaling signature for a separable upstream VEGF priming step, which can activate ECs to respond to downstream factors that are necessary to form branching tube networks with associated mural cells.

Glucose fluctuations promote vascular BK channels dysfunction via PKCα/NF-κB/MuRF1 signaling

Glucose fluctuations may contribute to large conductance calcium activated potassium (BK) channel dysfunction. However, the underlying mechanisms remain elusive. The aim of this study was to investigate the molecular mechanisms involved in BK channel dysfunction as a result of glucose fluctuations. A rat diabetic model was established through the injection of streptozotocin. Glucose fluctuations in diabetic rats were induced via consumption and starvation. Rat coronary arteries were isolated and coronary vascular tensions were measured after three weeks. Rat coronary artery smooth muscle cells were isolated and whole-cell BK channel currents were recorded using a patch clamp technique. Human coronary artery smooth muscle cells in vitro were used to explore the underlying mechanisms. After incubation with iberiotoxin (IBTX), the Δ tensions (% Max) of rat coronary arteries in the controlled diabetes mellitus (C-DM), the uncontrolled DM (U-DM) and the DM with glucose fluctuation (GF-DM) groups were found to be 84.46 ± 5.75, 61.89 ± 10.20 and 14.77 ± 5.90, respectively (P < .05), while the current densities of the BK channels in the three groups were 43.09 ± 4.35 pA/pF, 34.23 ± 6.07 pA/pF and 17.87 ± 4.33 pA/pF, respectively (P < .05). The Δ tensions (% Max) of rat coronary arteries after applying IBTX in the GF-DM rats injected with 0.9% sodium chloride (NaCl) (GF-DM + NaCl) and the GF-DM rats injected with N-acetyl-L-cysteine (NAC) (GF-DM + NAC) groups were found to be 8.86 ± 1.09 and 48.90 ± 10.85, respectively (P < .05). Excessive oxidative stress and the activation of protein kinase C (PKC) α and nuclear factor (NF)-κB induced by glucose fluctuations promoted the decrease of BK-β1 expression, while the inhibition of reactive oxygen species (ROS), PKCα, NF-κB and muscle ring finger protein 1 (MuRF1) reversed this effect. Glucose fluctuations aggravate BK channel dysfunction via the ROS overproduction and the PKCα/NF-κB/MuRF1 signaling pathway.

Binge Alcohol Exposure in Adolescence Impairs Normal Heart Growth.

BackgroundApproximately 1 in 6 adolescents report regular binge alcohol consumption, and we hypothesize it affects heart growth during this period.Methods and ResultsAdolescent, genetically diverse, male Wistar rats were gavaged with water or ethanol once per day for 6 days. In vivo structure and function were assessed before and after exposure. Binge alcohol exposure in adolescence significantly impaired normal cardiac growth but did not affect whole‐body growth during adolescence, therefore this pathology was specific to the heart. Binge rats also exhibited signs of accelerated pathological growth (concentric cellular hypertrophy and thickening of the myocardial wall), suggesting a global reorientation from physiologic to pathologic growth. Binge rats compensated for their smaller filling volumes by increasing systolic function and sympathetic stimulation. Consequently, binge alcohol exposure increased PKA (protein kinase A) phosphorylation of troponin I, inducing myofilament calcium desensitization. Binge alcohol also impaired in vivo relaxation and increased titin‐based cellular stiffness due to titin phosphorylation by PKCα (protein kinase C α). Mechanistically, alcohol inhibited extracellular signal‐related kinase activity, a nodal signaling kinase activating physiology hypertrophy. Thus, binge alcohol exposure depressed genes involved in growth. These cardiac structural alterations from binge alcohol exposure persisted through adolescence even after cessation of ethanol exposure.ConclusionsAlcohol negatively impacts function in the adult heart, but the adolescent heart is substantially more sensitive to its effects. This difference is likely because adolescent binge alcohol impedes the normal rapid physiological growth and reorients it towards pathological hypertrophy. Many adolescents regularly binge alcohol, and here we report a novel pathological consequence as well as mechanisms involved.