PRKCB/protein kinase C, beta and the mitochondrial axis as key regulators of autophagy

The Wolfram-like variant WFS1E864K destabilizes MAM and compromises autophagy and mitophagy in human and mice

Dominant variants in WFS1 (wolframin ER transmembrane glycoprotein), the gene coding for a mitochondria-associated endoplasmic reticulum (ER) membrane (MAM) resident protein, have been associated with Wolfram-like syndrome (WLS). In vitro and in vivo, WFS1 loss results in reduced ER to mitochondria calcium (Ca2+) transfer, mitochondrial dysfunction, and enhanced macroautophagy/autophagy and mitophagy. However, in the WLS pathological context, whether the mutant protein triggers the same cellular processes is unknown. Here, we show that in human fibroblasts and murine neuronal cultures the WLS protein WFS1E864K leads to decreases in mitochondria bioenergetics and Ca2+ uptake, deregulation of the mitochondrial quality system mechanisms, and alteration of the autophagic flux. Moreover, in the Wfs1E864K mouse, these alterations are concomitant with a decrease of MAM number. These findings reveal pathophysiological similarities between WS and WLS, highlighting the importance of WFS1 for MAM's integrity and functionality. It may open new treatment perspectives for patients with WLS.Abbreviations: BafA1: bafilomycin A1; ER: endoplasmic reticulum; HSPA9/GRP75: heat shock protein family A (Hsp70) member 9; ITPR/IP3R: inositol 1,4,5-trisphosphate receptor; MAM: mitochondria-associated endoplasmic reticulum membrane; MCU: mitochondrial calcium uniporter; MFN2: mitofusin 2; OCR: oxygen consumption rate; ROS: reactive oxygen species; ROT/AA: rotenone+antimycin A; VDAC1: voltage dependent anion channel 1; WLS: Wolfram-like syndrome; WS: Wolfram syndrome; WT: wild-type.

MITOCHONDRIAL ANTIVIRAL PATHWAYS CONTROL ANTI-HIV RESPONSES AND ISCHEMIC STROKE OUTCOMES VIA THE RIG-1 SIGNALING AND INNATE IMMUNITY MECHANISMS

Occludin (ocln) is one of the main regulatory cells of the blood-brain barrier (BBB). Ocln silencing resulted in alterations of the gene expression signatures of a variety of genes of the innate immunity system, including IFN-stimulated genes (ISGs) and the antiviral retinoic acid-inducible gene-1 (RIG-1) signaling pathway, which functions as a regulator of the cytoplasmic sensors upstream of the mitochondrial antiviral signaling protein (MAVS). Indeed, we observed dysfunctional mitochondrial bioenergetics, dynamics, and autophagy in our system. Alterations of mitochondrial bioenergetics and innate immune protection translated into worsened ischemic stroke outcomes in EcoHIV-infected ocln deficient mice. Overall, these results allow for a better understanding of the molecular mechanisms of viral infection in the brain and describe a previously unrecognized role of ocln as a key factor in the control of innate immune responses and mitochondrial dynamics, which affect cerebral vascular diseases such as ischemic stroke.

Identification of novel N7-methylguanine-related gene signatures associated with ulcerative colitis and the association with biological therapy

OBJECTIVE

Ulcerative colitis (UC) is an inflammatory disease characterized by recurrent episodes of chronic intestinal inflammation. It is closely associated with immune dysregulation in the intestines. However, the mechanisms underlying the role of immune-related N7-methylguanosine (m7G) internal modification in UC remain unclear.

METHODS

We conducted a screening of differentially expressed genes (DEGs) associated with m7G and performed immune infiltration analysis. We then investigated the correlation between m7G-related DEGs and immune cells or pathways. To further explore the functional implications, we conducted functional enrichment analysis to identify gene modules that strongly correlated with hub gene expression. In addition, we constructed a miRNA regulatory network for the hub genes in UC. Furthermore, we examined the association between hub genes and disease remission in UC patients undergoing biologic therapy.

RESULTS

We obtained 13 m7G-related DEGs and conducted an in-depth analysis of immune infiltration. Among them, we identified five hub genes (NUDT7, NUDT12, POLR2H, QKI, and PRKCB) that showed diagnostic potential for UC. Through WGCNA and KEGG analysis, we found that gene modules strongly correlated with m7G hub gene expression were enriched in inflammation-related pathways. Furthermore, Kaplan-Meier survival analysis revealed a significant association between changes in hub gene expression levels and disease remission in UC patients undergoing biologic therapy.

CONCLUSION

The findings of this study demonstrate that five m7G-related DEGs, including the m7G-modified recognition protein QKI, play a key role in the occurrence and progression of UC intestinal inflammation, which is closely related to intestinal immunity. These results provide valuable insights into the mechanisms of m7G modification in UC development and offer new perspectives for exploring novel therapeutic targets for UC.

Multi-Stage Transcriptome Analysis Revealed the Growth Mechanism of Feathers and Hair Follicles during Induction Molting by Fasting in the Late Stage of Egg Laying

Induced molting is a common method to obtain a new life in laying hens, in which periodic changes in feathers are the prominent feature. Nevertheless, its precise molecular mechanism remains unclear. In this study, feather and hair follicle samples were collected during fasting-induced physiological remodeling for hematoxylin-eosin staining, hormone changes and follicle traits, and transcriptome sequencing. Feather shedding was observed in F13 to R25, while newborns were observed in R3 to R32. Triiodothyronine and tetraiodothyronine were significantly elevated during feather shedding. The calcium content was significantly higher, and the ash content was significantly lower after the changeover. The determination of hair follicle traits revealed an increasing trend in pore density and a decrease in pore diameter after the resumption of feeding. According to RNA-seq results, several core genes were identified, including DSP, CDH1, PKP1, and PPCKB, which may have an impact on hair follicle growth. The focus was to discover that starvation may trigger changes in thyroid hormones, which in turn regulate feather molting through thyroid hormone synthesis, calcium signaling, and thyroid hormone signaling pathways. These data provide a valuable resource for the analysis of the molecular mechanisms underlying the cyclical growth of hair follicles in the skin during induced molting.

Evolutionary analysis of the mTOR pathway provide insights into lifespan extension across mammals

BACKGROUND

Lifespan extension has independently evolved several times during mammalian evolution, leading to the emergence of a group of long-lived animals. Though mammalian/mechanistic target of rapamycin (mTOR) signaling pathway is shown as a central regulator of lifespan and aging, the underlying influence of mTOR pathway on the evolution of lifespan in mammals is not well understood.

RESULTS

Here, we performed evolution analyses of 72 genes involved in the mTOR network across 48 mammals to explore the underlying mechanism of lifespan extension. We identified a total of 20 genes with significant evolution signals unique to long-lived species, including 12 positively selected genes, four convergent evolution genes, and five longevity associated genes whose evolution rate related to the maximum lifespan (MLS). Of these genes, four positively selected genes, two convergent evolution genes and one longevity-associated gene were involved in the autophagy response and aging-related diseases, while eight genes were known as cancer genes, indicating the long-lived species might have evolved effective regulation mechanisms of autophagy and cancer to extend lifespan.

CONCLUSION

Our study revealed genes with significant evolutionary signals unique to long-lived species, which provided new insight into the lifespan extension of mammals and might bring new strategies to extend human lifespan.

Hepatic protein kinase Cbeta deficiency mitigates late-onset obesity

Although aging is associated with progressive adiposity and a decline in liver function, the underlying molecular mechanisms and metabolic interplay are incompletely understood. Here, we demonstrate that aging induces hepatic protein kinase Cbeta (PKCβ) expression, while hepatocyte PKCβ deficiency (PKCβHep-/-) in mice significantly attenuates obesity in aged mice fed a high-fat diet. Compared with control PKCβfl/fl mice, PKCβHep-/- mice showed elevated energy expenditure with augmentation of oxygen consumption and carbon dioxide production which was dependent on β3-adrenergic receptor signaling, thereby favoring negative energy balance. This effect was accompanied by induction of thermogenic genes in brown adipose tissue (BAT) and increased BAT respiratory capacity, as well as a shift to oxidative muscle fiber type with an improved mitochondrial function, thereby enhancing oxidative capacity of thermogenic tissues. Furthermore, in PKCβHep-/- mice, we determined that PKCβ overexpression in the liver mitigated elevated expression of thermogenic genes in BAT. In conclusion, our study thus establishes hepatocyte PKCβ induction as a critical component of pathophysiological energy metabolism by promoting progressive hepatic and extrahepatic metabolic derangements in energy homeostasis, contributing to late-onset obesity. These findings have potential implications for augmenting thermogenesis as a means of combating aging-induced obesity.

Hakuna MAM-Tata: Investigating the role of mitochondrial-associated membranes in ALS

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease leading to selective and progressive motor neuron (MN) death. Despite significant heterogeneity in pathogenic and clinical terms, MN demise ultimately unifies patients. Across the many disturbances in neuronal biology present in the disease and its models, two common trends are loss of calcium homeostasis and dysregulations in lipid metabolism. Since both mitochondria and endoplasmic reticulum (ER) are essential in these functions, their intertwin through the so-called mitochondrial-associated membranes (MAMs) should be relevant in this disease. In this review, we present a short overview of MAMs functional aspects and how its dysfunction could explain a substantial part of the cellular disarrangements in ALS's natural history. MAMs are hubs for lipid synthesis, integrating glycerophospholipids, sphingolipids, and cholesteryl ester metabolism. These lipids are essential for membrane biology, so there should be a close coupling to cellular energy demands, a role that MAMs may partially fulfill. Not surprisingly, MAMs are also host part of calcium signaling to mitochondria, so their impairment could lead to mitochondrial dysfunction, affecting oxidative phosphorylation and enhancing the vulnerability of MNs. We present data supporting that MAMs' maladaptation could be essential to MNs' vulnerability in ALS.

NRF2 signaling pathway: A comprehensive prognostic and gene expression profile analysis in breast cancer

Breast cancer is the most frequently diagnosed malignant tumor in women and a major public health concern. NRF2 axis is a cellular protector signaling pathway protecting both normal and cancer cells from oxidative damage. NRF2 is a transcription factor that binds to the gene promoters containing antioxidant response element-like sequences. In this report, differential expression of NRF2 signaling pathway elements, as well as the correlation of NRF2 pathway mRNAs with various clinicopathologic characteristics, including molecular subtypes, tumor grade, tumor stage, and methylation status, has been investigated in breast cancer using METABRIC and TCGA datasets. In the current report, our findings revealed the deregulation of several NRF2 signaling elements in breast cancer patients. Moreover, there were negative correlations between the methylation of NRF2 genes and mRNA expression. The expression of NRF2 genes significantly varied between different breast cancer subtypes. In conclusion, substantial deregulation of NRF2 signaling components suggests an important role of these genes in breast cancer. Because of the clear associations between mRNA expression and methylation status, DNA methylation could be one of the mechanisms that regulate the NRF2 pathway in breast cancer. Differential expression of Hippo genes among various breast cancer molecular subtypes suggests that NRF2 signaling may function differently in different subtypes of breast cancer. Our data also highlights an interesting link between NRF2 components' transcription and tumor grade/stage in breast cancer.

The inhibition of MDM2 slows cell proliferation and activates apoptosis in ADPKD cell lines

INTRODUCTION

Autosomal dominant polycystic kidney disease (ADPKD) is characterised by progressive cysts formation and renal enlargement that in most of cases leads to end stage of renal disease (ESRD). This pathology is caused by mutations of either PKD1 or PKD2 genes that encode for polycystin-1 (PC1) and polycystin-2 (PC2), respectively. These proteins function as receptor-channel complex able to regulate calcium homeostasis. PKD1/2 loss of function impairs different signalling pathways including cAMP and mTOR that are considered therapeutic targets for this disease. In fact, Tolvaptan, a vasopressin-2 antagonist that reduces cAMP levels, is the only drug approved for ADPKD treatment. Nevertheless, some ADPKD patients developed side effects in response to Tolvaptan including liver damage. Conversely, mTOR inhibitors that induced disease regression in ADPKD animal models failed the clinical trials.

RESULTS

Here, we show that the inhibition of mTOR causes the activation of autophagy in ADPKD cells that could reduce therapy effectiveness by drug degradation through the autophagic vesicles. Consistently, the combined treatment with rapamycin and chloroquine, an autophagy inhibitor, potentiates the decrease of cell proliferation induced by rapamycin. To overcome the dangerous activation of autophagy by mTOR inhibition, we targeted MDM2 (a downstream effector of mTOR signalling) that is involved in TP53 degradation by using RG7112, a small-molecule MDM2 inhibitor used for the treatment of haematologic malignancies. The inhibition of MDM2 by RG7112 prevents TP53 degradation and increases p21 expression leading to the decrease of cell proliferation and the activation of apoptosis.

CONCLUSION

The targeting of MDM2 by RG7112 might represent a new therapeutic option for the treatment of ADPKD.

Ageing-Associated Transcriptomic Alterations in Peri-Implantitis Pathology: A Bioinformatic Study

Background

Ageing is associated with increased incidence of peri-implantitis but the roles of ageing-associated biological mechanisms in the occurrence of peri-implantitis are not known. This study is aimed at performing integrative bioinformatic analysis of publically available datasets to uncover molecular mechanisms related to ageing and peri-implantitis.

Methods

Gene expression datasets related to ageing and peri-implantitis (PI) were sought, and differentially expressed genes (DEGs) were analysed. Ageing-related genes were also identified from the "Aging Atlas" database. Using intersection analysis, an age-related-PI gene set was identified. Functional enrichment analysis for enriched GO biological process and KEGG pathways, protein-protein interaction (PPI) network analysis, correlation analysis, and immune cell infiltration analysis to determine high-abundance immune cells were performed. Least absolute shrinkage and selection operator (LASSO) logistic regression identified key age-related-PI genes. Transcription factor-gene and drug-gene interactions and enriched KEGG pathways for the key age-related-PI genes were determined.

Results

A total of 52 genes were identified as age-related-PI genes and found enriched in several inflammation-associated processes including myeloid leukocyte activation, acute inflammatory response, mononuclear cell differentiation, B cell activation, NF-kappa B signalling, IL-17 signalling, and TNF signalling. LYN, CDKN2A, MAPT, BTK, and PRKCB were hub genes in the PPI network. Immune cell infiltration analysis showed activated dendritic cells, central memory CD4 T cells, immature dendritic cells, and plasmacytoid dendritic cells were highly abundant in PI and ageing. 7 key age-related PI genes including ALOX5AP, EAF2, FAM46C, GZMK, MAPT, RGS1, and SOSTDC1 were identified using LASSO with high predictive values and found to be enriched in multiple neurodegeneration-associated pathways, MAPK signalling, and Fc epsilon RI signalling. MAPT and ALOX5AP were associated with multiple drugs and transcription factors and interacted with other age-related genes to regulate multiple biological pathways.

Conclusion

A suite of bioinformatics analysis identified a 7-signature gene set highly relevant to cooccurrence of ageing and peri-implantitis and highlighted the role of neurodegeneration, autoimmune, and inflammation related pathways. MAPT and ALOX5AP were identified as key candidate target genes for clinical translation.

Pathological mitophagy disrupts mitochondrial homeostasis in Leber's hereditary optic neuropathy

Leber’s hereditary optic neuropathy (LHON), a disease associated with a mitochondrial DNA mutation, is characterized by blindness due to degeneration of retinal ganglion cells (RGCs) and their axons, which form the optic nerve. We show that a sustained pathological autophagy and compartment-specific mitophagy activity affects LHON patient-derived cells and cybrids, as well as induced pluripotent-stem-cell-derived neurons. This is variably counterbalanced by compensatory mitobiogenesis. The aberrant quality control disrupts mitochondrial homeostasis as reflected by defective bioenergetics and excessive reactive oxygen species production, a stress phenotype that ultimately challenges cell viability by increasing the rate of apoptosis. We counteract this pathological mechanism by using autophagy regulators (clozapine and chloroquine) and redox modulators (idebenone), as well as genetically activating mitochondrial biogenesis (PGC1-α overexpression). This study substantially advances our understanding of LHON pathophysiology, providing an integrated paradigm for pathogenesis of mitochondrial diseases and druggable targets for therapy.

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Autophagy and mitophagy are abnormally activated in samples carrying LHON mutations

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Autophagy and mitophagy affect LHON cells’ viability

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Therapeutic approaches targeting autophagy reverts LHON cells’ apoptotic death

The Combination of Salidroside and Hedysari Radix Polysaccharide Inhibits Mitochondrial Damage and Apoptosis via the PKC/ERK Pathway

Background. Beta-amyloid (Aβ) peptide is a widely recognized pathological marker of Alzheimer’s disease (AD). Salidroside and Hedysari Radix polysaccharide (HRP) were extracted from Chinese herb medicine Rhodiola rosea L and Hedysarum polybotrys Hand-Mazz, respectively. The neuroprotective effects and mechanisms of the combination of salidroside and Hedysari Radix polysaccharide (CSH) against Aβ25–35 induced neurotoxicity remain unclear. Objective. This study aims to investigate the neuroprotective effects and pharmacological mechanisms of CSH on Aβ25–35-induced HT22 cells. Materials and Methods. HT22 cells were pretreated with various concentrations of salidroside or HRP for 24 h, followed by exposed to 20 μm Aβ25–35 in the presence of salidroside or RHP for another 24 h. In a CSH protective assay, HT22 cells were pretreated with 40 μm salidroside and 20 μg/mL HRP for 24 h. The cell viability assay, cell morphology observation, determination of mitochondrial membrane potential (MMP), reactive oxygen species (ROS), and cell apoptosis rate were performed. The mRNA expression of protein kinase C-beta (PKCβ), Bax, and Bcl-2 were measured by qRT-PCR. The protein expression levels of cleaved caspase-3, Cyt-C, PKCβ, phospho-ERK1/2, Bax, and Bcl-2 were measured by Western blot. Results. CSH treatment increased cell viability, MMP, and decreased ROS generation in Aβ25–35-induced HT22 cells. PKCβ and Bcl-2 mRNA expression were elevated by CSH while Bax was decreased. CSH increased the protein expression levels of PKCβ, Bcl-2, and phospho-ERK1/2, and decreased those of Bax, Cyt-C, and cleaved caspase-3. Conclusions. CSH treatment have protective effects against Aβ25–35-induced cytotoxicity through decreasing ROS levels, increasing MMP, inhibiting early apoptosis, and regulating PKC/ERK pathway in HT22 cells. CSH may be a potential therapeutic agent for treating or preventing neurodegenerative diseases.

p66Shc in Cardiovascular Pathology

p66Shc is a widely expressed protein that governs a variety of cardiovascular pathologies by generating, and exacerbating, pro-apoptotic ROS signals. Here, we review p66Shc’s connections to reactive oxygen species, expression, localization, and discuss p66Shc signaling and mitochondrial functions. Emphasis is placed on recent p66Shc mitochondrial function discoveries including structure/function relationships, ROS identity and regulation, mechanistic insights, and how p66Shc-cyt c interactions can influence p66Shc mitochondrial function. Based on recent findings, a new p66Shc mitochondrial function model is also put forth wherein p66Shc acts as a rheostat that can promote or antagonize apoptosis. A discussion of how the revised p66Shc model fits previous findings in p66Shc-mediated cardiovascular pathology follows.

Liquid biopsy, using a novel DNA methylation signature, distinguishes pancreatic adenocarcinoma from benign pancreatic disease

We tested the ability of a novel DNA methylation biomarker set to distinguish metastatic pancreatic cancer cases from benign pancreatic cyst patients and to monitor tumor dynamics using quantitative DNA methylation analysis of cell-free DNA (cfDNA) from blood samples. The biomarkers were able to distinguish malignant cases from benign disease with high sensitivity and specificity (AUC = 0.999). Furthermore, the biomarkers detected a consistent decline in tumor-derived cfDNA in samples from patients undergoing chemotherapy. The study indicates that our liquid biopsy assay could be useful for management of pancreatic cancer patients.

A Risk Score Signature Consisting of Six Immune Genes Predicts Overall Survival in Patients with Lower-Grade Gliomas

Background. Lower-grade gliomas (LGGs) are less aggressive with a long overall survival (OS) time span. Because of individualized genomic features, a prognostic system incorporating molecular signatures can more accurately predict OS. Methods. Differential expression analysis between LGGs and normal tissues was performed using the Gene Expression Omnibus (GEO) datasets (GSE4290 and GSE12657). Immune-related differentially expressed genes (ImmPort-DEGs) were analyzed for functional enrichment. The least absolute shrinkage and selection operator (LASSO) analysis was performed to develop an immune risk score signature (IRSS). We extracted information from the Cancer Genome Atlas (TCGA) and the Chinese Glioma Genome Atlas (CGGA) to establish and validate the model. The relationship of model gene sets with immune infiltration was analyzed based on gene set variation analysis (GSVA) scores. Patients were divided into low- and high-risk groups based on the median score. The time-dependent receiver-operating characteristic (ROC) curve and the Kaplan-Meier curve were used to evaluate the model. Then, a precise prognostic nomogram was established, and its efficacy was verified. Results. A total of 18 related immune genes were identified, building a 6-gene IRSS (BMP2, F2R, FGF13, PCSK1, PRKCB, and PTGER3). DEGs were enriched in T cell and NK cell regulatory pathways. Immune infiltration analysis confirmed that the gene signature correlated with a decrease in innate immune cells. In terms of model evaluation, ROC curves at 1, 3, and 5 years showed moderate predictive ability of IRSS ( $\text{AUC}=0.930$ , 0.797, and 0.728). The Cox regression analysis revealed that IRSS was an independent prognostic factor, and the nomogram model had good predictive ability ( $\text{C}-\text{index}=0.828$ ). Meanwhile, the predictive power of IRSS was also confirmed in the training cohort. The Kaplan-Meier results showed that the prognosis of the high-risk group was significantly worse in all cohorts. Conclusion. IRSS may serve as a novel survival prediction tool in the classification of LGG patients.

Activation of the sigma-1 receptor chaperone alleviates symptoms of Wolfram syndrome in preclinical models

The Wolfram syndrome is a rare autosomal recessive disease affecting many organs with life-threatening consequences; currently, no treatment is available. The disease is caused by mutations in the WSF1 gene, coding for the protein wolframin, an endoplasmic reticulum (ER) transmembrane protein involved in contacts between ER and mitochondria termed as mitochondria-associated ER membranes (MAMs). Inherited mutations usually reduce the protein's stability, altering its homeostasis and ultimately reducing ER to mitochondria calcium ion transfer, leading to mitochondrial dysfunction and cell death. In this study, we found that activation of the sigma-1 receptor (S1R), an ER-resident protein involved in calcium ion transfer, could counteract the functional alterations of MAMs due to wolframin deficiency. The S1R agonist PRE-084 restored calcium ion transfer and mitochondrial respiration in vitro, corrected the associated increased autophagy and mitophagy, and was able to alleviate the behavioral symptoms observed in zebrafish and mouse models of the disease. Our findings provide a potential therapeutic strategy for treating Wolfram syndrome by efficiently boosting MAM function using the ligand-operated S1R chaperone. Moreover, such strategy might also be relevant for other degenerative and mitochondrial diseases involving MAM dysfunction.

Clinical Relevance of Secreted Small Noncoding RNAs in an Embryo Implantation Potential Prediction at Morula and Blastocyst Development Stages

Despite the improvements in biotechnological approaches and the selection of controlled ovarian hyperstimulation protocols, the resulting pregnancy rate from in vitro fertilization (IVF) protocols still does not exceed 30-40%. In this connection, there is an acute question of the development of a non-invasive, sensitive, and specific method for assessing the implantation potential of an embryo. A total of 110 subfertile couples were included in the study to undergo the IVF/ICSI program. Obtained embryos for transfer into the uterine cavity of patient cohort 1 (n = 60) and cohort 2 (n = 50) were excellent/good-quality blastocysts, and small noncoding RNA (sncRNA) content in the corresponding spent culture medium samples at the morula stage (n = 43) or at the blastocyst stage (n = 31) was analyzed by deep sequencing followed by qRT-PCR in real time. Two logistic regression models were developed to predict the implantation potential of the embryo with 100% sensitivity and 100% specificity: model 1 at the morula stage, using various combinations of hsa_piR_022258, hsa-let-7i-5p, hsa_piR_000765, hsa_piR_015249, hsa_piR_019122, and hsa_piR_008112, and model 2 at the blastocyst stage, using various combinations of hsa_piR_020497, hsa_piR_008113, hsa-miR-381-3p, hsa_piR_022258, and hsa-let-7a-5p. Protein products of sncRNA potential target genes participate in the selective turnover of proteins through the ubiquitination system and in the organization of the various cell cytoskeleton and nucleoskeleton structures, regulating the activity of the Hippo signaling pathway, which determines the fate specification of the blastomers.

A Focal Adhesion-Related Gene Signature Predicts Prognosis in Glioma and Correlates With Radiation Response and Immune Microenvironment

Background

Glioma is the most frequent brain malignancy presenting very poor prognosis and high recurrence rate. Focal adhesion complexes play pivotal roles in cell migration and act as hubs of several signaling pathways.

Methods

We used bioinformatic databases (CGGA, TCGA, and GEO) and identified a focal adhesion-related differential gene expression (FADG) signature by uniCox and LASSO regression analysis. We calculated the risk score of every patient using the regression coefficient value and expression of each gene. Survival analysis, receiver operating characteristic curve (ROC), principal component analysis (PCA), and stratified analysis were used to validate the FADG signature. Then, we conducted GSEA to identify the signaling pathways related to the FADG signature. Correlation analysis of risk scores between the immune checkpoint was performed. In addition, the correlation of risk scores and genes related with DNA repair was performed. CIBERSORT and ssGSEA were used to explore the tumor microenvironment (TME). A nomogram that involved our FADG signature was also constructed.

Results

In total, 1,726 (528 patients diagnosed with WHO II, 591 WHO III, and 603 WHO IV) cases and 23 normal samples were included in our study. We identified 29 prognosis-related genes in the LASSO analysis and constructed an eight FADG signature. The results from the survival analysis, stratified analysis, ROC curve, and univariate and multivariate regression analysis revealed that the prognosis of the high-risk group was significantly worse than the low-risk group. Correlation analysis between risk score and genes that related with DNA repair showed that the risk score was positively related with BRCA1, BRCA2, RAD51, TGFB1, and TP53. Besides, we found that the signature could predict the prognosis of patients who received radiation therapy. SsGSEA indicated that the high-risk score was positively correlated with the ESTIMATE, immune, and stromal scores but negatively correlated with tumor purity. Notably, patients in the high-risk group had a high infiltration of immunocytes. The correlation analysis revealed that the risk score was positively correlated with B7-H3, CTLA4, LAG3, PD-L1, and TIM3 but inversely correlated with PD-1.

Conclusion

The FADG signature we constructed could provide a sensitive prognostic model for patients with glioma and contribute to improve immunotherapy management guidelines.

Methods to Monitor Mitophagy and Mitochondrial Quality: Implications in Cancer, Neurodegeneration, and Cardiovascular Diseases

Mitochondria are dynamic organelles that participate in a broad array of molecular functions within the cell. They are responsible for maintaining the appropriate energetic levels and control the cellular homeostasis throughout the generation of intermediary metabolites. Preserving a healthy and functional mitochondrial population is of fundamental importance throughout the life of the cells under pathophysiological conditions. Hence, cells have evolved fine-tuned mechanisms of quality control that help to preserve the right amount of functional mitochondria to meet the demand of the cell. The specific recycling of mitochondria by autophagy, termed mitophagy, represents the primary contributor to mitochondrial quality control. During this process, damaged or unnecessary mitochondria are recognized and selectively degraded. In the past few years, the knowledge in mitophagy has seen rapid progress, and a growing body of evidence confirms that mitophagy holds a central role in controlling cellular functions and the progression of various human diseases.In this chapter, we will discuss the pathophysiological roles of mitophagy and provide a general overview of the current methods used to monitor and quantify mitophagy. We will also outline the main established approaches to investigate the mitochondrial function, metabolism, morphology, and protein damage.

mTORC2: The other mTOR in autophagy regulation

The mechanistic target of rapamycin (mTOR) has gathered significant attention as a ubiquitously expressed multimeric kinase with key implications for cell growth, proliferation, and survival. This kinase forms the central core of two distinct complexes, mTORC1 and mTORC2, which share the ability of integrating environmental, nutritional, and hormonal cues but which regulate separate molecular pathways that result in different cellular responses. Particularly, mTORC1 has been described as a major negative regulator of endosomal biogenesis and autophagy, a catabolic process that degrades intracellular components and organelles within the lysosomes and is thought to play a key role in human health and disease. In contrast, the role of mTORC2 in the regulation of autophagy has been considerably less studied despite mounting evidence this complex may regulate autophagy in a different and perhaps complementary manner to that of mTORC1. Genetic ablation of unique subunits is currently being utilized to study the differential effects of the two mTOR complexes. RICTOR is the best‐described subunit specific to mTORC2 and as such has become a useful tool for investigating the specific actions of this complex. The development of complex‐specific inhibitors for mTORC2 is also an area of intense interest. Studies to date have demonstrated that mTORC1/2 complexes each signal to a variety of exclusive downstream molecules with distinct biological roles. Pinpointing the particular effects of these downstream effectors is crucial toward the development of novel therapies aimed at accurately modulating autophagy in the context of human aging and disease.

DNA Damage, n-3 Long-Chain PUFA Levels and Proteomic Profile in Brazilian Children and Adolescents

Fatty acids play a significant role in maintaining cellular and DNA protection and we previously found an inverse relationship between blood levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and DNA damage. The aim of this study was to explore differences in proteomic profiles, for 117 pro-inflammatory proteins, in two previously defined groups of individuals with different DNA damage and EPA and DHA levels. Healthy children and adolescents (n = 140) aged 9 to 13 years old in an urban area of Brazil were divided by k-means cluster test into two clusters of DNA damage (tail intensity) using the comet assay (cluster 1 = 5.9% ± 1.2 and cluster 2 = 13.8% ± 3.1) in our previous study. The cluster with higher DNA damage and lower levels of DHA (6.2 ± 1.6 mg/dL; 5.4 ± 1.3 mg/dL, p = 0.003) and EPA (0.6 ± 0.2 mg/dL; 0.5 ± 0.1 mg/dL, p < 0.001) presented increased expression of the proteins CDK8-CCNC, PIK3CA-PIK3R1, KYNU, and PRKCB, which are involved in pro-inflammatory pathways. Our findings support the hypothesis that low levels of n-3 long-chain PUFA may have a less protective role against DNA damage through expression of pro-inflammatory proteins, such as CDK8-CCNC, PIK3CA-PIK3R1, KYNU, and PRKCB.

Differentially Expressed MiRNAs of Goat Submandibular Glands Among Three Developmental Stages Are Involved in Immune Functions

Submandibular glands (SMGs) are one of the primary components of salivary glands in goats. The proteins and biologically active substances secreted by the SMGs change with growth and development. Our previous studies showed that most of the differentially expressed genes in the SMGs of goats at different developmental stages are involved in immune-related signaling pathways, but the miRNA expression patterns in the same tissues are unknown. The aim of this study was to reveal the expression profile of miRNAs at three different developmental stages, detect differentially expressed miRNAs (DE miRNAs) and predict disease-related DE miRNAs. SMG tissue samples were collected from groups of 1-month-old kids, 12-month-old maiden goats and 24-month-old adult goats (three samples from each group), and high-throughout transcriptome sequencing was conducted. A total of 178, 241 and 7 DE miRNAs were discovered between 1-month-old kids and 12-month-old maiden goats, between 1-month-old kids and 24-month-old adult goats, and between 12-month-old maiden goats and 24-month-old adult goats, respectively. Among these DE miRNAs, 88 DE miRNAs with medium or high expression levels (TPM ≥50) were classified into five expression pattern clusters. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses indicated that some of the predicted target genes of the DE miRNAs in the five clusters were enriched in disease-related GO terms and pathways. MiRNA target genes in significant pathways were significantly enriched in Hepatitis B (FDR = 9.03E-10) and Pathways in cancer (FDR = 4.2E-10). Further analysis was performed with a PPI network, and 10 miRNAs were predicted to play an important role in the occurrence and prevention of diseases during the growth and development of goats.

Selective inhibition of PKCβ2 improves Caveolin-3/eNOS signaling and attenuates lipopolysaccharide-induced injury by inhibiting autophagy in H9C2 cardiomyocytes

Lipopolysaccharide (LPS)-induced autophagy is involved in sepsis-associated myocardial injury with increased PKCβ2 activation. We previously found hyperglycemia-induced PKCβ2 activation impaired the expression of caveolin-3 (Cav-3), the dominant isoform to form cardiomyocytes caveolae which modulate eNOS signaling to confer cardioprotection in diabetes. However, little is known about the roles of PKCβ2 in autophagy and Cav-3/eNOS signaling in cardiomyocytes during LPS exposure. We hypothesize LPS-induced PKCβ2 activation promotes autophagy and impairs Cav-3/eNOS signaling in LPS-treated cardiomyocytes. H9C2 cardiomyocytes were treated with LPS (10 µg/mL) in the presence or absence of PKCβ2 inhibitor CGP53353 (CGP, 1 µM) or autophagy inhibitor 3-methyladenine (3-MA, 10 µM). LPS stimulation induced cytotoxicity overtime in H9C2 cardiomyocytes, accompanied with excessive PKCβ2 activation. Selective inhibition of PKCβ2 with CGP significantly reduced LPS-induced cytotoxicity and autophagy (measured by LC-3II, Beclin-1, p62 and autophagic flux). In addition, CGP significantly attenuated LPS-induced oxidative injury, and improved Cav-3 expression and eNOS activation, similar effects were shown by the treatment of autophagy inhibitor 3-MA. LPS-induced myocardial injury is associated with excessive PKCβ2 activation, which contributes to elevated autophagy and impaired Cav-3/eNOS signaling. Selective inhibition of PKCβ2 improves Cav-3/eNOS signaling and attenuates LPS-induced injury through inhibiting autophagy in H9C2 cardiomyocytes.

Genome-wide association study of individual differences of human lymphocyte profiles using large-scale cytometry data

Human immune systems are very complex, and the basis for individual differences in immune phenotypes is largely unclear. One reason is that the phenotype of the immune system is so complex that it is very difficult to describe its features and quantify differences between samples. To identify the genetic factors that cause individual differences in whole lymphocyte profiles and their changes after vaccination without having to rely on biological assumptions, we performed a genome-wide association study (GWAS), using cytometry data. Here, we applied computational analysis to the cytometry data of 301 people before receiving an influenza vaccine, and 1, 7, and 90 days after the vaccination to extract the feature statistics of the lymphocyte profiles in a nonparametric and data-driven manner. We analyzed two types of cytometry data: measurements of six markers for B cell classification and seven markers for T cell classification. The coordinate values calculated by this method can be treated as feature statistics of the lymphocyte profile. Next, we examined the genetic basis of individual differences in human immune phenotypes with a GWAS for the feature statistics, and we newly identified seven significant and 36 suggestive single-nucleotide polymorphisms associated with the individual differences in lymphocyte profiles and their change after vaccination. This study provides a new workflow for performing combined analyses of cytometry data and other types of genomics data.

VDAC1 promotes cardiomyocyte autophagy in anoxia/reoxygenation injury via the PINK1/Parkin pathway

Ischemia/reperfusion (I/R) is a well-known injury to the myocardium, but the mechanism involved remains elusive. In addition to the well-accepted apoptosis theory, autophagy was recently found to be involved in the process, exerting a dual role as protection in ischemia and detriment in reperfusion. Activation of autophagy is mediated by mitochondrial permeability transition pore (MPTP) opening during reperfusion. In our previous study, we showed that MPTP opening is regulated by VDAC1, a channel protein located in the outer membrane of mitochondria. Thus, upregulation of VDAC1 expression is a possible trigger to cardiomyocyte autophagy via an unclear pathway. Here, we established an anoxia/reoxygenation (A/R) model in vitro to simulate the I/R process in vivo. At the end of A/R treatment, VDAC1, Beclin 1, and LC3-II/I were upregulated, and autophagic vacuoles were increased in cardiomyocytes, which showed a connection of VDAC1 and autophagy development. These variations also led to ROS burst, mitochondrial dysfunction, and aggravated apoptosis. Knockdown of VDAC1 by RNAi could alleviate the above-mentioned cellular damages. Additionally, the expression of PINK1 and Parkin was enhanced after A/R injury. Furthermore, Parkin was recruited to mitochondria from the cytosol, which suggested that the PINK1/Parkin autophagic pathway was activated during A/R. Nevertheless, the PINK1/Parkin pathway was effectively inhibited when VDAC1 was knocked-down. Taken together, the A/R-induced cardiomyocyte injury was mediated by VDAC1 upregulation, which led to cell autophagy via the PINK1/Parkin pathway, and finally aggravated apoptosis.

Deciphering the autophagy regulatory network via single-cell transcriptome analysis reveals a requirement for autophagy homeostasis in spermatogenesis

Background: Autophagy has been implicated as a crucial component in spermatogenesis, and autophagy dysfunction can lead to reproductive disorders in animal models, including yeast, C. elegans and mice. However, the sophisticated transcriptional networks of autophagic genes throughout human spermatogenesis and their biological significance remain largely uncharacterized. Methods: We profiled the transcriptional signatures of autophagy-related genes during human spermatogenesis by assessing specimens from nine fertile controls (including two normal persons and seven obstructive azoospermia (OA) patients) and one nonobstructive azoospermia (NOA) patient using single-cell RNA sequencing (scRNA-seq) analysis. Dysregulation of autophagy was confirmed in two additional NOA patients by immunofluorescence staining. Gene knockdown was used to identify the role of Cst3 in autophagy during spermatogenesis. Results: Our data uncovered a unique, global stage-specific enrichment of autophagy-related genes. Human-mouse comparison analysis revealed that the stage-specific expression pattern of autophagy-related genes was highly conserved in mammals. More importantly, dysregulation of some clusters of autophagy-related genes was observed in NOA patients, suggesting the association of autophagy with male infertility. Cst3, a human-mouse conserved and autophagy-related gene that is actively expressed in spermatogonia and early spermatocytes, was found to regulate spermatogonial stem cell (SSC) maintenance and subsequent male germ cell development. Knockdown of Cst3 increased autophagic activity in mouse SSCs and subsequently suppressed the transcription of SSC core factors such as Oct4, Id1, and Nanos3, which could be efficiently rescued by manipulating autophagic activity. Conclusions: Our study provides comprehensive insights into the global transcriptional signatures of autophagy-related genes and confirms the importance of autophagy homeostasis in SSC maintenance and normal spermatogenesis, opening new avenues for further dissecting the significance of the autophagy regulatory network in spermatogenesis as well as male infertility.

Mitochondrial Oxidative Stress and "Mito-Inflammation": Actors in the Diseases

A decline in mitochondrial redox homeostasis has been associated with the development of a wide range of inflammatory-related diseases. Continue discoveries demonstrate that mitochondria are pivotal elements to trigger inflammation and stimulate innate immune signaling cascades to intensify the inflammatory response at front of different stimuli. Here, we review the evidence that an exacerbation in the levels of mitochondrial-derived reactive oxygen species (ROS) contribute to mito-inflammation, a new concept that identifies the compartmentalization of the inflammatory process, in which the mitochondrion acts as central regulator, checkpoint, and arbitrator. In particular, we discuss how ROS contribute to specific aspects of mito-inflammation in different inflammatory-related diseases, such as neurodegenerative disorders, cancer, pulmonary diseases, diabetes, and cardiovascular diseases. Taken together, these observations indicate that mitochondrial ROS influence and regulate a number of key aspects of mito-inflammation and that strategies directed to reduce or neutralize mitochondrial ROS levels might have broad beneficial effects on inflammatory-related diseases.

Hepatocyte-specific PKCβ deficiency protects against high-fat diet-induced nonalcoholic hepatic steatosis

OBJECTIVE

Nonalcoholic hepatic steatosis, also known as fatty liver, is a uniform response of the liver to hyperlipidic-hypercaloric diet intake. However, the post-ingestive signals and mechanistic processes driving hepatic steatosis are not well understood. Emerging data demonstrate that protein kinase C beta (PKCβ), a lipid-sensitive kinase, plays a critical role in energy metabolism and adaptation to environmental and nutritional stimuli. Despite its powerful effect on glucose and lipid metabolism, knowledge of the physiological roles of hepatic PKCβ in energy homeostasis is limited.

METHODS

The floxed-PKCβ and hepatocyte-specific PKCβ-deficient mouse models were generated to study the in vivo role of hepatocyte PKCβ on diet-induced hepatic steatosis, lipid metabolism, and mitochondrial function.

RESULTS

We report that hepatocyte-specific PKCβ deficiency protects mice from development of hepatic steatosis induced by high-fat diet, without affecting body weight gain. This protection is associated with attenuation of SREBP-1c transactivation and improved hepatic mitochondrial respiratory chain. Lipidomic analysis identified significant increases in the critical mitochondrial inner membrane lipid, cardiolipin, in PKCβ-deficient livers compared to control. Moreover, hepatocyte PKCβ deficiency had no significant effect on either hepatic or whole-body insulin sensitivity supporting dissociation between hepatic steatosis and insulin resistance.

CONCLUSIONS

The above data indicate that hepatocyte PKCβ is a key focus of dietary lipid perception and is essential for efficient storage of dietary lipids in liver largely through coordinating energy utilization and lipogenesis during post-prandial period. These results highlight the importance of hepatic PKCβ as a drug target for obesity-associated nonalcoholic hepatic steatosis.

Mining GWAS and eQTL data for CF lung disease modifiers by gene expression imputation

Genome wide association studies (GWAS) have identified several genomic loci with candidate modifiers of cystic fibrosis (CF) lung disease, but only a small proportion of the expected genetic contribution is accounted for at these loci. We leveraged expression data from CF cohorts, and Genotype-Tissue Expression (GTEx) reference data sets from multiple human tissues to generate predictive models, which were used to impute transcriptional regulation from genetic variance in our GWAS population. The imputed gene expression was tested for association with CF lung disease severity. By comparing and combining results from alternative approaches, we identified 379 candidate modifier genes. We delved into 52 modifier candidates that showed consensus between approaches, and 28 of them were near known GWAS loci. A number of these genes are implicated in the pathophysiology of CF lung disease (e.g., immunity, infection, inflammation, HLA pathways, glycosylation, and mucociliary clearance) and the CFTR protein biology (e.g., cytoskeleton, microtubule, mitochondrial function, lipid metabolism, endoplasmic reticulum/Golgi, and ubiquitination). Gene set enrichment results are consistent with current knowledge of CF lung disease pathogenesis. HLA Class II genes on chr6, and CEP72, EXOC3, and TPPP near the GWAS peak on chr5 are most consistently associated with CF lung disease severity across the tissues tested. The results help to prioritize genes in the GWAS regions, predict direction of gene expression regulation, and identify new candidate modifiers throughout the genome for potential therapeutic development.

MiR-215-5p Reduces Liver Metastasis in an Experimental Model of Colorectal Cancer through Regulation of ECM-Receptor Interactions and Focal Adhesion

Simple Summary

Decreased expression of miR-215-5-p was found in tumor tissue of patients with colorectal cancer (CRC) in comparison to healthy colon tissue. Moreover, expression levels of miR-215-5p were further decreased in metastatic lesions compared to primary tumor tissue. Overall, CRC patients with lower expression of miR-215-5p in tumors had significantly shorter overall survival and a higher chance of metastasis. This study aimed to examine the effects of miR-215-5p supplementation on the metastatic potential of CRC. MiR-215-5p was found to decrease invasiveness, migratory capacity, tumorigenicity, and metastasis formation. Finally, transcriptome analysis identified signaling pathways involved in the process, and subsequent RT-qPCR validation indicates CTNNBIP1 to be a direct target of this microRNA. These results bring new insight into miR-215-5p biology, a molecule that could potentially serve as a promising target for CRC patients’ future therapeutic strategies.

Abstract

Background: Growing evidence suggests that miR-215-5p is a tumor suppressor in colorectal cancer (CRC); however, its role in metastasis remains unclear. This study evaluates the effects of miR-215 overexpression on the metastatic potential of CRC. Methods: CRC cell lines were stably transfected with miR-215-5p and used for in vitro and in vivo functional analyses. Next-generation sequencing and RT-qPCR were performed to study changes on the mRNA level. Results: Overexpression of miR-215-5p significantly reduced the clonogenic potential, migration, and invasiveness of CRC cells in vitro and tumor weight and volume, and liver metastasis in vivo. Transcriptome analysis revealed mRNAs regulated by miR-215-5p and RT-qPCR confirmed results for seven selected genes. Significantly elevated levels of CTNNBIP1 were also observed in patients’ primary tumors and liver metastases compared to adjacent tissues, indicating its direct regulation by miR-215-5p. Gene Ontology and KEGG pathway analysis identified cellular processes and pathways associated with miR-215-5p deregulation. Conclusions: MiR-215-5p suppresses the metastatic potential of CRC cells through the regulation of divergent molecular pathways, including extracellular-matrix-receptor interaction and focal adhesion. Although the specific targets of miR-215-5p contributing to the formation of distant metastases must be further elucidated, this miRNA could serve as a promising target for CRC patients’ future therapeutic strategies.

Protein Interaction Studies for Understanding the Tremor Pathway in Parkinson's Disease

BACKGROUND

Tremor is one of the most noticeable features, which occurs during the early stages of Parkinson's Disease (PD). It is one of the major pathological hallmarks and does not have any interpreted mechanism. In this study, we have framed a hypothesis and deciphered protein- protein interactions between the proteins involved in impairment in sodium and calcium ion channels and thus cause synaptic plasticity leading to a tremor.

METHODS

Literature mining for retrieval of proteins was done using Science Direct, PubMed Central, SciELO and JSTOR databases. A well-thought approach was used, and a list of differentially expressed proteins in PD was collected from different sources. A total of 71 proteins were retrieved, and a protein interaction network was constructed between them by using Cytoscape.v.3.7. The network was further analysed using the BiNGO plugin for retrieval of overrepresented biological processes in Tremor-PD datasets. Hub nodes were also generated in the network.

RESULTS

The Tremor-PD pathway was deciphered, which demonstrates the cascade of protein interactions that might lead to tremors in PD. Major proteins involved were LRRK2, TUBA1A, TRAF6, HSPA5, ADORA2A, DRD1, DRD2, SNCA, ADCY5, TH, etc. Conclusion: In the current study, it is predicted that ADORA2A and DRD1/DRD2 are equally contributing to the progression of the disease by inhibiting the activity of adenylyl cyclase and thereby increases the permeability of the blood-brain barrier, causing an influx of neurotransmitters and together they alter the level of dopamine in the brain which eventually leads to tremor.

The induction of AMPK-dependent autophagy leads to P53 degradation and affects cell growth and migration in kidney cancer cells

The most common subtype of renal cell carcinoma (RCC) is the clear cell RCC (ccRCC) that accounts for 70-80% of cases. The fate of ccRCC is linked to alterations of genes that regulate TP53. The dysfunction of p53 affects several processes including autophagy, which is increased in different advanced carcinomas and could be associated with cancer progression. We report that different kidney cancer cell lines show higher levels of autophagy than control cells. The increased autophagy is associated with the upregulation of miR501-5p, which stimulates mTOR-independent autophagy by the activation of AMP kinase. AMPK activation occurs through the decrease of ATP generation caused by the downregulation of the mitochondrial calcium uniporter (MCU) that leads to the reduction of mitochondrial calcium uptake. Autophagy induction promotes the degradation of p53 through the autophagolysosomal machinery. Consistently, the inhibition of autophagy reduces both cell proliferation and migration enhancing the expression of p53, p21 and E-Cadherin as well as decreasing Vimentin synthesis. Taken together, these findings indicate that autophagy is involved in the progression of kidney cancer. Therefore, the pharmacological targeting of this process could be considered an interesting option for the treatment of advanced renal carcinoma.

Physiopathology of the Permeability Transition Pore: Molecular Mechanisms in Human Pathology

Mitochondrial permeability transition (MPT) is the sudden loss in the permeability of the inner mitochondrial membrane (IMM) to low-molecular-weight solutes. Due to osmotic forces, MPT is paralleled by a massive influx of water into the mitochondrial matrix, eventually leading to the structural collapse of the organelle. Thus, MPT can initiate outer-mitochondrial-membrane permeabilization (MOMP), promoting the activation of the apoptotic caspase cascade and caspase-independent cell-death mechanisms. The induction of MPT is mostly dependent on mitochondrial reactive oxygen species (ROS) and Ca²⁺, but is also dependent on the metabolic stage of the affected cell and signaling events. Therefore, since its discovery in the late 1970s, the role of MPT in human pathology has been heavily investigated. Here, we summarize the most significant findings corroborating a role for MPT in the etiology of a spectrum of human diseases, including diseases characterized by acute or chronic loss of adult cells and those characterized by neoplastic initiation.

The Inhibition of Protein Kinase C β Contributes to the Pathogenesis of Preeclampsia by Activating Autophagy

Background

Preeclampsia is a devastating hypertensive disorder of pregnancy with unknown mechanism. Recent studies have considered abnormal autophagy as a new cellular mechanism for this disorder, while little is known about how autophagy is specifically involved and what factors are implicated. Here, we report a previously unrecognized preeclampsia-associated autophagic regulator, PKCβ, that is involved in placental angiogenesis.

Methods

PKCβ levels were evaluated by quantitative real-time PCR, western blotting, immunofluorescence and by the analysis of public data. The autophagy-regulating role of PKCβ inhibition in preeclampsia pathogenesis was studied in a mouse model, and in human umbilical vein endothelial cells (HUVECs) and human choriocarcinoma cells (JEG-3).

Findings

PKCβ was significantly downregulated in human preeclamptic placentas. In a mouse model, the selective inhibition of PKCβ by Ruboxistaurin was sufficient to induce preeclampsia-like symptoms, accompanied by excessive autophagic flux and a disruption in the balance of pro- and anti-angiogenic factors in mouse placentas. In contrast, autophagic inhibition by 3-methyladenine partially normalized hypertension, proteinuria and placental angiogenic imbalance in PKCβ-inhibited mice. Our in vitro experiments demonstrated that PKCβ inhibition activated autophagy, thus blocking VEGFA-induced HUVEC tube formation and resulting in the significant upregulation of sFLT1 and downregulation of VEGFA in JEG-3 cells.

Interpretation

These data support a novel model in which autophagic activation due to PKCβ inhibition leads to the impairment of angiogenesis and eventually results in preeclampsia.

Funding

Shanghai Key Program of Clinical Science and Technology Innovation, National Natural Science Foundation of China and Shanghai Medical Center of Key Programs for Female Reproductive Diseases.

ER membranes associated with mitochondria: Possible therapeutic targets in heart-associated diseases

Cardiovascular system cell biology is tightly regulated and mitochondria play a relevant role in maintaining heart function. In recent decades, associations between such organelles and the sarco/endoplasmic reticulum (SR) have been raised great interest. Formally identified as mitochondria-associated SR membranes (MAMs), these structures regulate different cellular functions, including calcium management, lipid metabolism, autophagy, oxidative stress, and management of unfolded proteins. In this review, we highlight MAMs' alterations mainly in cardiomyocytes, linked with cardiovascular diseases, such as cardiac ischemia-reperfusion, heart failure, and dilated cardiomyopathy. We also describe proteins that are part of the MAMs' machinery, as the FUN14 domain containing 1 (FUNDC1), the sigma 1 receptor (Sig-1R) and others, which might be new molecular targets to preserve the function and structure of the heart in such diseases. Understanding the machinery of MAMs and its function demands our attention, as such knowledge might contribute to strengthen the role of these relative novel structures in heart diseases.

Selective Inhibition of PKCβ2 Restores Ischemic Postconditioning-Mediated Cardioprotection by Modulating Autophagy in Diabetic Rats

Diabetic hearts are more susceptible to myocardial ischemia/reperfusion (I/R) injury and less sensitive to ischemic postconditioning (IPostC), but the underlying mechanisms remain unclear. PKCβ2 is preferentially overactivated in diabetic myocardium, in which autophagy status is abnormal. This study determined whether hyperglycemia-induced PKCβ2 activation resulted in autophagy abnormality and compromised IPostC cardioprotection in diabetes. We found that diabetic rats showed higher cardiac PKCβ2 activation and lower autophagy than control at baseline. However, myocardial I/R further increased PKCβ2 activation and promoted autophagy status in diabetic rats. IPostC significantly attenuated postischemic infarct size and CK-MB, accompanied with decreased PKCβ2 activation and autophagy in control but not in diabetic rats. Pretreatment with CGP53353, a selective inhibitor of PKCβ2, attenuated myocardial I/R-induced infarction and autophagy and restored IPostC-mediated cardioprotection in diabetes. Similarly, CGP53353 could restore hypoxic postconditioning (HPostC) protection against hypoxia reoxygenation- (HR-) induced injury evidenced by decreased LDH release and JC-1 monomeric cells and increased cell viability. These beneficial effects of CGP53353 were reversed by autophagy inducer rapamycin, but could be mimicked by autophagy inhibitor 3-MA. It is concluded that selective inhibition of PKCβ2 could attenuate myocardial I/R injury and restore IPostC-mediated cardioprotection possibly through modulating autophagy in diabetes.

Recent Insights into the Mitochondrial Role in Autophagy and Its Regulation by Oxidative Stress

Autophagy is a self-digestive process that degrades intracellular components, including damaged organelles, to maintain energy homeostasis and to cope with cellular stress. Autophagy plays a key role during development and adult tissue homeostasis, and growing evidence indicates that this catalytic process also has a direct role in modulating aging. Although autophagy is essentially protective, depending on the cellular context and stimuli, autophagy outcome can lead to either abnormal cell growth or cell death. The autophagic process requires a tight regulation, with cellular events following distinct stages and governed by a wide molecular machinery. Reactive oxygen species (ROS) have been involved in autophagy regulation through multiple signaling pathways, and mitochondria, the main source of endogenous ROS, have emerged as essential signal transducers that mediate autophagy. In the present review, we aim to summarize the regulatory function of mitochondria in the autophagic process, particularly regarding the mitochondrial role as the coordination node in the autophagy signaling pathway, involving mitochondrial oxidative stress, and their participation as membrane donors in the initial steps of autophagosome assembly.

Crosstalk between Mitochondrial Ca2+ Uptake and Autophagy in Skeletal Muscle

Autophagy is responsible for the maintenance of skeletal muscle homeostasis, thanks to the removal of aberrant and dysfunctional macromolecules and organelles. During fasting, increased autophagy ensures the maintenance of the amino acid pool required for energy production. The activity of the mitochondrial Ca²⁺ uniporter (MCU), the highly selective channel responsible for mitochondrial Ca²⁺ uptake, controls skeletal muscle size, force, and nutrient utilization. Thus, both autophagy and mitochondrial Ca²⁺ accumulation play a pivotal role to maintain muscle homeostasis and to sustain muscle function. Here, we address whether, in skeletal muscle, mitochondrial Ca²⁺ uptake and autophagy are mutually related. Muscle-restricted MCU silencing partially inhibits the autophagy flux. Moreover, skeletal muscle-specific deletion of the essential autophagy gene Atg7, known to cause the accumulation of dysfunctional mitochondria, drastically reduces mitochondrial Ca²⁺ accumulation. Thus, a vicious cycle takes place, in which reduced MCU activity hampers the autophagic flux, and loss of autophagy further impairs mitochondrial Ca²⁺ signaling.

Modulation of Obesity and Insulin Resistance by the Redox Enzyme and Adaptor Protein p66Shc

Initially reported as a longevity-related protein, the 66 kDa isoform of the mammalian Shc1 locus has been implicated in several metabolic pathways, being able to act both as an adaptor protein and as a redox enzyme capable of generating reactive oxygen species (ROS) when it localizes to the mitochondrion. Ablation of p66^Shc has been shown to be protective against obesity and the insurgence of insulin resistance, but not all the studies available in the literature agree on these points. This review will focus in particular on the role of p66^Shc in the modulation of glucose homeostasis, obesity, body temperature, and respiration/energy expenditure. In view of the obesity and diabetes epidemic, p66^Shc may represent a promising therapeutic target with enormous implications for human health.

Natural pyrethrins induce autophagy of HepG2 cells through the activation of AMPK/mTOR pathway

Natural pyrethrins, one kind of insects' neural toxin, have been used worldwide for the control of pests of crops, livestock, and human beings. However, their specific mechanisms of action are incompletely understood and hence further investigation is required. Here we used a series of experiments including colony formation, fluorescent staining, western blotting, enzyme activity detection, immunofluorescence analysis, and real-time quantitative PCR (QPCR) to investigate whether natural pyrethrins (0-40 μg/mL) are able to modulate autophagy process through AMPK/mTOR signaling pathway, in order to reveal their cytotoxic mechanisms. The results showed that natural pyrethrins markedly inhibited the proliferation of HepG2 cells in both concentration- and time-dependent manners. Particularly, natural pyrethrins could induce the resulting autophagosome, and the intensification of LC3-II formation and translocation, the accumulation of Beclin-1 and the reduction of p62 and thus autophagy. We clarified that natural pyrethrins induced the abnormal level of oxidation reduction metabolism, leading to mitochondrial permeability transition pore (mPTP) opening, ATP depletion and mitochondria eliminating by autophagy. Moreover, the phosphorylation levels of AMPK were significantly enhanced, and the mTOR and p70s6k phosphorylation were drastically decreased. These results showed that natural pyrethrins induced autophagy of HepG2 cells and activation of the AMPK/mTOR signaling pathway might have potential risk to human health.

The roles of PKCs in regulating autophagy

PURPOSE

Autophagy, as a highly conserved cellular degradation and recycling process, plays an important part in maintaining cellular homeostasis. PKC signaling is involved in multiple pathways including cell cycle progression, tumorigenesis, migration and autophagy.

METHODS

Literatures about PKC and autophagy from PubMed databases were reviewed in this study.

RESULTS

Studies regarding the association of PKC and autophagy remain debatable. Different duration of the stimulation of autophagy and distinct cell contexts result in different function of PKC in regulating autophagy. The subcellular localization of PKCs and their downstream regulators may influence the autophagy regulation as well. As important intracellular components, the mitochondria play an important role in regulating autophagy, by metabolic modulation and structural derangement.

CONCLUSION

Phase II studies regarding PKC-β inhibitor, enzastaurin, showed promising results in MCL, DLBCL and recurrent high-grade gliomas. However, the detailed mechanism is still in need. The mechanism of PKC-β in mediating autophagy in lymphoma and high-grade gliomas remains elusive as well. Moreover, several studies were in agreement that rottlerin enhanced autophagy in breast cancer cells, which warrants further clinical studies to verify PKC-δ as a therapeutic target. Thus, identifying the function of PKC in modulating autophagy and conducting related clinical studies help find novel target for chemotherapy.

Regulation of PKCβ levels and autophagy by PML is essential for high-glucose-dependent mesenchymal stem cell adipogenesis

BACKGROUND/OBJECTIVES

Obesity is a complex disease characterized by the accumulation of excess body fat, which is caused by an increase in adipose cell size and number. The major source of adipocytes comes from mesenchymal stem cells (MSCs), although their roles in obesity remain unclear. An understanding of the mechanisms, regulation, and outcomes of adipogenesis is crucial for the development of new treatments for obesity-related diseases. Recently an unexpected role for the tumor suppressor promyelocytic leukemia protein (PML) in hematopoietic stem cell biology and metabolism regulation has come to light, but its role in MSC biology remains unknown. Here, we investigated the molecular pathway underlying the role of PML in the control of adipogenic MSC differentiation.

SUBJECTS/METHODS

Muscle-derived stem cells (MDSCs) and adipose-derived stem cells (ADSCs) obtained from mice and voluntary patients (as a source of MSCs) were cultured in the presence of high glucose (HG) concentration, a nutrient stress condition known to promote MSCs differentiation into mature adipocytes and the adipogenic potential of PML was assessed.

RESULTS

PML is essential for a correct HG-dependent adipogenic differentiation, and the enhancement of PML levels is fundamental during adipogenesis. Increased PML expression enables the upregulation of protein kinase Cβ (PKCβ), which, in turn, by controlling autophagy levels permits an increase in peroxisome proliferator-activated receptor γ (PPARγ) that leads the adipogenic differentiation. Therefore, genetic and pharmacological depletion of PML prevents PKCβ expression, and by increasing autophagy levels, impairs the MSCs adipogenic differentiation. Human ADSCs isolated from overweight patients displayed increased PML and PKCβ levels compared to those found in normal weight individuals, indicating that the PML-PKCβ pathway is directly involved in the enhancement of adipogenesis and human metabolism.

CONCLUSIONS

The new link found among PML, PKCβ, and autophagy opens new therapeutic avenues for diseases characterized by an imbalance in the MSCs differentiation process, such as metabolic syndromes and cancer.

Glycine Protects H9C2 Cardiomyocytes from High Glucose- and Hypoxia/Reoxygenation-Induced Injury via Inhibiting PKCβ2 Activation and Improving Mitochondrial Quality

BACKGROUND

Patients with diabetes are more vulnerable to myocardial ischemia reperfusion injury (IRI), which is involved in PKCβ2 activation and mitochondrial dysfunction. Glycine has been documented as a cytoprotective agent to attenuate diabetes-related abnormalities and reduce myocardial IRI, but the underlying mechanisms are still unclear. We determined whether glycine could attenuate high glucose- (HG-) and hypoxia/reoxygenation- (H/R-) induced injury by inhibiting PKCβ2 activation and improving mitochondrial quality in cultured H9C2 cells.

METHODS

H9C2 cells were either exposed to low glucose (LG) or HG conditions with or without treatment of glycine or CGP53353 (a selective inhibitor of PKCβ2) for 48 h, then subjected to 4 h of hypoxia followed by 2 h of reoxygenation (H/R). Cell viability, lactate dehydrogenase (LDH) release, mitochondrial membrane potential (MMP), superoxide dismutase (SOD) activity, and malondialdehyde (MDA) concentration were detected using corresponding commercial kits. Mitochondrial quality control-related proteins (LC-3II, Mfn-2, and Cyt-C) and PKCβ2 activation were detected by Western blot.

RESULTS

HG stimulation significantly decreased cell viability and SOD activity and increased LDH release, MDA production, and PKCβ2 activation as compared to LG group, all of which changes were further increased by H/R insult. Glycine or CGP53353 treatment significantly reduced the increase of LDH release, MDA production, PKCβ2 activation, and Cyt-C expression and the decrease of cell viability, SOD activity, MMP, Mfn-2 expression, and LC-3II/LC-3I ratio induced by HG and H/R stimulation.

CONCLUSIONS

Supplementary glycine protects H9C2 cells from HG- and H/R-induced cellular injury by suppressing PKCβ2 activation and improving mitochondria quality.

Protein Kinase C β: a New Target Therapy to Prevent the Long-Term Atypical Antipsychotic-Induced Weight Gain

Antipsychotic drugs are currently used in clinical practice for a variety of mental disorders. Among them, clozapine is the most effective medication for treatment-resistant schizophrenia and is most helpful in controlling aggression and the suicidal behavior in schizophrenia and schizoaffective disorder. Although clozapine is associated with a low likelihood of extrapyramidal symptoms and other neurological side effects, it is well known for the weight gain and metabolic side effects, which expose the patient to a greater risk of cardiovascular disorders and premature death, as well as psychosocial issues, leading to non-adherence to therapy. The mechanisms underlying these iatrogenic metabolic disorders are still controversial. We have therefore investigated the in vivo effects of the selective PKCβ inhibitor, ruboxistaurin (LY-333531), in a preclinical model of long-term clozapine-induced weight gain. Cell biology, biochemistry, and behavioral tests have been performed in wild-type and PKCβ knockout mice to investigate the contribution of endogenous PKCβ and its pharmacological inhibition to the psychomotor effects of clozapine. Finally, we also shed light on a novel aspect of the mechanism underlying the clozapine-induced weight gain, demonstrating that the clozapine-dependent PKCβ activation promotes the inhibition of the lipid droplet-selective autophagy process. This paves the way to new therapeutic approaches to this serious complication of clozapine therapy.

Dietary fat/cholesterol-sensitive PKCβ-RB signaling: Potential role in NASH/HCC axis

Hepatocellular carcinoma (HCC) is a frequent form of cancer with a poor prognosis, and environmental factors significantly contribute to the risk. Despite knowledge that a Western-style diet is a risk factor in the development of nonalcoholic steatohepatitis (NASH) and subsequent progression to HCC, diet-induced signaling changes are not well understood. Understanding molecular mechanisms altered by diet is crucial for developing preventive and therapeutic strategies. We have previously shown that diets enriched with high-fat and high-cholesterol, shown to produce NASH and HCC, induce hepatic protein kinase C beta (PKCβ) expression in mice, and a systemic loss of PKCβ promotes hepatic cholesterol accumulation in response to this diet. Here, we sought to determine how PKCβ and diet functionally interact during the pathogenesis of NASH and how it may promote hepatic carcinogenesis. We found that diet-induced hepatic PKCβ expression is accompanied by an increase in phosphorylation of Ser780 of retinoblastoma (RB) protein. Intriguingly, PKCβ^-/- livers exhibited reduced RB protein levels despite increased transcription of the RB gene. It is also accompanied by reduced RBL-1 with no significant effect on RBL-2 protein levels. We also found reduced expression of the PKCβ in HCC compared to non-tumorous liver in human patients. These results raise an interesting possibility that diet-induced PKCβ activation represents an important mediator in the functional wiring of cholesterol metabolism and tumorigenesis through modulating stability of cell cycle-associated proteins. The potential role of PKCβ in the suppression of tumorigenesis is discussed.

Calcium regulates cell death in cancer: Roles of the mitochondria and mitochondria-associated membranes (MAMs)

Until 1972, the term 'apoptosis' was used to differentiate the programmed cell death that naturally occurs in organismal development from the acute tissue death referred to as necrosis. Many studies on cell death and programmed cell death have been published and most are, at least to some degree, related to cancer. Some key proteins and molecular pathways implicated in cell death have been analyzed, whereas others are still being actively researched; therefore, an increasing number of cellular compartments and organelles are being implicated in cell death and cancer. Here, we discuss the mitochondria and subdomains of the endoplasmic reticulum (ER) that interact with mitochondria, the mitochondria-associated membranes (MAMs), which have been identified as critical hubs in the regulation of cell death and tumor growth. MAMs-dependent calcium (Ca²⁺) release from the ER allows selective Ca²⁺ uptake by the mitochondria. The perturbation of Ca²⁺ homeostasis in cancer cells is correlated with sustained cell proliferation and the inhibition of cell death through the modulation of Ca²⁺ signaling. This article is part of a Special Issue entitled Mitochondria in Cancer, edited by Giuseppe Gasparre, Rodrigue Rossignol and Pierre Sonveaux.

Methods to Assess Mitochondrial Morphology in Mammalian Cells Mounting Autophagic or Mitophagic Responses

It is widely acknowledged that mitochondria are highly active structures that rapidly respond to cellular and environmental perturbations by changing their shape, number, and distribution. Mitochondrial remodeling is a key component of diverse biological processes, ranging from cell cycle progression to autophagy. In this chapter, we describe different methodologies for the morphological study of the mitochondrial network. Instructions are given for the preparation of samples for fluorescent microscopy, based on genetically encoded strategies or the employment of synthetic fluorescent dyes. We also propose detailed protocols to analyze mitochondrial morphometric parameters from both three-dimensional and bidimensional datasets. Finally, we describe a protocol for the visualization and quantification of mitochondrial structures through electron microscopy.