Deficiency of the transcriptional regulator p8 results in increased autophagy and apoptosis, and causes impaired heart function

Microgravity triggers ferroptosis and accelerates senescence in the MG-63 cell model of osteoblastic cells

In space, cells sustain strong modifications of their mechanical environment. Mechanosensitive molecules at the cell membrane regulate mechanotransduction pathways that induce adaptive responses through the regulation of gene expression, post-translational modifications, protein interactions or intracellular trafficking, among others. In the current study, human osteoblastic cells were cultured on the ISS in microgravity and at 1 g in a centrifuge, as onboard controls. RNAseq analyses showed that microgravity inhibits cell proliferation and DNA repair, stimulates inflammatory pathways and induces ferroptosis and senescence, two pathways related to ageing. Morphological hallmarks of senescence, such as reduced nuclear size and changes in chromatin architecture, proliferation marker distribution, tubulin acetylation and lysosomal transport were identified by immunofluorescence microscopy, reinforcing the hypothesis of induction of cell senescence in microgravity during space flight. These processes could be attributed, at least in part, to the regulation of YAP1 and its downstream effectors NUPR1 and CKAP2L.

Beyond the amyloid hypothesis: how current research implicates autoimmunity in Alzheimer's disease pathogenesis

The amyloid hypothesis has so far been at the forefront of explaining the pathogenesis of Alzheimer's Disease (AD), a progressive neurodegenerative disorder that leads to cognitive decline and eventual death. Recent evidence, however, points to additional factors that contribute to the pathogenesis of this disease. These include the neurovascular hypothesis, the mitochondrial cascade hypothesis, the inflammatory hypothesis, the prion hypothesis, the mutational accumulation hypothesis, and the autoimmunity hypothesis. The purpose of this review was to briefly discuss the factors that are associated with autoimmunity in humans, including sex, the gut and lung microbiomes, age, genetics, and environmental factors. Subsequently, it was to examine the rise of autoimmune phenomena in AD, which can be instigated by a blood-brain barrier breakdown, pathogen infections, and dysfunction of the glymphatic system. Lastly, it was to discuss the various ways by which immune system dysregulation leads to AD, immunomodulating therapies, and future directions in the field of autoimmunity and neurodegeneration. A comprehensive account of the recent research done in the field was extracted from PubMed on 31 January 2022, with the keywords "Alzheimer's disease" and "autoantibodies" for the first search input, and "Alzheimer's disease" with "IgG" for the second. From the first search, 19 papers were selected, because they contained recent research on the autoantibodies found in the biofluids of patients with AD. From the second search, four papers were selected. The analysis of the literature has led to support the autoimmune hypothesis in AD. Autoantibodies were found in biofluids (serum/plasma, cerebrospinal fluid) of patients with AD with multiple methods, including ELISA, Mass Spectrometry, and microarray analysis. Through continuous research, the understanding of the synergistic effects of the various components that lead to AD will pave the way for better therapeutic methods and a deeper understanding of the disease.

Insights from a Computational-Based Approach for Analyzing Autophagy Genes across Human Cancers

In the last decade, there has been a boost in autophagy reports due to its role in cancer progression and its association with tumor resistance to treatment. Despite this, many questions remain to be elucidated and explored among the different tumors. Here, we used omics-based cancer datasets to identify autophagy genes as prognostic markers in cancer. We then combined these findings with independent studies to further characterize the clinical significance of these genes in cancer. Our observations highlight the importance of innovative approaches to analyze tumor heterogeneity, potentially affecting the expression of autophagy-related genes with either pro-tumoral or anti-tumoral functions. In silico analysis allowed for identifying three genes (TBC1D12, KERA, and TUBA3D) not previously described as associated with autophagy pathways in cancer. While autophagy-related genes were rarely mutated across human cancers, the expression profiles of these genes allowed the clustering of different cancers into three independent groups. We have also analyzed datasets highlighting the effects of drugs or regulatory RNAs on autophagy. Altogether, these data provide a comprehensive list of targets to further the understanding of autophagy mechanisms in cancer and investigate possible therapeutic targets.

Circulating cardiac MicroRNAs safeguard against dilated cardiomyopathy

BACKGROUND

Cardiac-resident or -enriched microRNAs (miRNAs) could be released into the bloodstream becoming circulating cardiac miRNAs, which are increasingly recognized as non-invasive and accessible biomarkers of multiple heart diseases. However, dilated cardiomyopathy (DCM)-associated circulating miRNAs (DACMs) and their roles in DCM pathogenesis remain largely unexplored.

METHODS

Two human cohorts, consisting of healthy individuals and DCM patients, were enrolled for serum miRNA sequencing (10 vs. 10) and quantitative polymerase chain reaction validation (46 vs. 54), respectively. Rigorous screening strategy was enacted to define DACMs and their potentials for diagnosis. DCM mouse model, different sources of cardiomyocytes, adeno-associated virus 9 (AAV9), gene knockout, RNAscope miRNA in situ hybridization, mRFP-GFP-LC3B reporter, echocardiography and transmission electron microscopy were adopted for mechanistic explorations.

RESULTS

Serum miRNA sequencing revealed a unique expression pattern for DCM circulating miRNAs. DACMs miR-26a-5p, miR-30c-5p, miR-126-5p and miR-126-3p were found to be depleted in DCM circulation as well as heart tissues. Their expressions in circulation and heart tissues were proven to be correlated significantly, and a combination of these miRNAs was suggested potential values for DCM diagnosis. FOXO3, a predicted common target, was experimentally demonstrated to be co-repressed within cardiomyocytes by these DACMs except miR-26a-5p. Delivery of a combination of miR-30c-5p, miR-126-5p and miR-126-3p into the murine myocardium via AAV9 carrying an expression cassette driven by cTnT promoter, or cardiac-specific knockout of FOXO3 (Myh6-CreERT2 , FOXO3 flox+/+ ) dramatically attenuated cardiac apoptosis and autophagy involved in DCM progression. Moreover, competitively disrupting the interplay between DACMs and FOXO3 mRNA by specifically introducing their interacting regions into murine myocardium crippled the cardioprotection of DACMs against DCM.

CONCLUSIONS

Circulating cardiac miRNA-FOXO3 axis plays a pivotal role in safeguarding against myocardial apoptosis and excessive autophagy in DCM development, which may provide serological cues for DCM non-invasive diagnosis and shed light on DCM pathogenesis and therapeutic targets.

Partial Inhibition of Complex I Restores Mitochondrial Morphology and Mitochondria-ER Communication in Hippocampus of APP/PS1 Mice

Alzheimer's disease (AD) has no cure. Earlier, we showed that partial inhibition of mitochondrial complex I (MCI) with the small molecule CP2 induces an adaptive stress response, activating multiple neuroprotective mechanisms. Chronic treatment reduced inflammation, Aβ and pTau accumulation, improved synaptic and mitochondrial functions, and blocked neurodegeneration in symptomatic APP/PS1 mice, a translational model of AD. Here, using serial block-face scanning electron microscopy (SBFSEM) and three-dimensional (3D) EM reconstructions combined with Western blot analysis and next-generation RNA sequencing, we demonstrate that CP2 treatment also restores mitochondrial morphology and mitochondria-endoplasmic reticulum (ER) communication, reducing ER and unfolded protein response (UPR) stress in the APP/PS1 mouse brain. Using 3D EM volume reconstructions, we show that in the hippocampus of APP/PS1 mice, dendritic mitochondria primarily exist as mitochondria-on-a-string (MOAS). Compared to other morphological phenotypes, MOAS have extensive interaction with the ER membranes, forming multiple mitochondria-ER contact sites (MERCS) known to facilitate abnormal lipid and calcium homeostasis, accumulation of Aβ and pTau, abnormal mitochondrial dynamics, and apoptosis. CP2 treatment reduced MOAS formation, consistent with improved energy homeostasis in the brain, with concomitant reductions in MERCS, ER/UPR stress, and improved lipid homeostasis. These data provide novel information on the MOAS-ER interaction in AD and additional support for the further development of partial MCI inhibitors as a disease-modifying strategy for AD.

The expression of apoptosis related genes in HK-2 cells overexpressing PPM1K was determined by RNA-seq analysis

Chronic kidney disease (CKD) is a serious disease that endangers human health. It is reported that inhibiting renal cell apoptosis can delay the progress of CKD. Our previous study found that the mice with protein phosphatase Mg2+/Mn2+ dependent 1K (PPM1K) gene deletion had obvious symptoms of glomerular vascular and interstitial vascular dilatation, congestion and hemorrhage, glomerular hemorrhage and necrosis, interstitial fibrous tissue proliferation, decreased urinary creatinine clearance, and increased urinary protein level. In addition, studies have found that PPM1K is essential for cell survival, apoptosis and metabolism. However, no study has confirmed that PPM1K can inhibit renal cell apoptosis. In this study, PPM1K was overexpressed in human kidney-2 cells (HK-2), and the biological process of differentially expressed genes and its effect on apoptosis were comprehensively screened by RNA sequencing (RNA-seq). Through sequencing analysis, we found that there were 796 differentially expressed genes in human renal tubular epithelial cells transfected with PPM1K gene, of which 553 were down-regulated and 243 were up-regulated. Enrichment analysis found that differentially expressed genes may play an important role in amino acid metabolism and biosynthesis. In the GO analysis functional pathway list, we also found that multiple genes can be enriched in apoptosis related pathways, such as G0S2, GADD45A, TRIB3, VEGFA, NUPR1 and other up-regulated genes, and IL-6, MAGED1, CCL2, TP53INP1 and other down-regulated genes. Then we verified these differentially expressed genes by RT-PCR, and found that only the RT-PCR results of G0S2, VEGFA and NUPR1 were consistent with the transcriptome sequencing results. We believe that G0S2, VEGFA, NUPR1 and other genes may participate in the apoptosis process of HK-2 cells induced by PPM1K.In conclusion, these findings provide some data support for the study of HK-2 cell apoptosis mechanism, and also provide a scientific theoretical basis for further study of the effect of PPM1K on kidney disease.

Integrative Analyses of Genes Associated With Right Ventricular Cardiomyopathy Induced by Tricuspid Regurgitation

Tricuspid regurgitation (TR) induces right ventricular cardiomyopathy, a common heart disease, and eventually leads to severe heart failure and serious clinical complications. Accumulating evidence shows that long non-coding RNAs (lncRNAs) are involved in the pathological process of a variety of cardiovascular diseases. However, the regulatory mechanisms and functional roles of RNA interactions in TR-induced right ventricular cardiomyopathy are still unclear. Accordingly, we performed integrative analyses of genes associated with right ventricular cardiomyopathy induced by TR to study the roles of lncRNAs in the pathogenesis of this disease. In this study, we used high-throughput sequencing data of tissue samples from nine clinical cases of right ventricular myocardial cardiomyopathy induced by TR and nine controls with normal right ventricular myocardium from the Genotype-Tissue Expression database. We identified differentially expressed lncRNAs and constructed a protein-protein interaction and lncRNA-messenger RNA (mRNA) co-expression network. Furthermore, we determined hub lncRNA-mRNA modules related to right ventricular myocardial disease induced by TR and constructed a competitive endogenous RNA network for TR-induced right ventricular myocardial disease by integrating the interaction of lncRNA-miRNA-mRNA. In addition, we analyzed the immune infiltration using integrated data and the correlation of each immune-related gene with key genes of the integrated expression matrix. The present study identified 648 differentially expressed mRNAs, 201 differentially expressed miRNAs, and 163 differentially expressed lncRNAs. Protein-protein interaction network analysis confirmed that ADRA1A, AVPR1B, OPN4, IL-1B, IL-1A, CXCL4, ADCY2, CXCL12, GNB4, CCL20, CXCL8, and CXCL1 were hub genes. CTD-2314B22.3, hsa-miR-653-5p, and KIF17ceRNA; SRGAP3-AS2, hsa-miR-539-5p, and SHANK1; CERS6-AS1, hsa-miR-497-5p, and OPN4; INTS6-AS1, hsa-miR-4262, and NEURL1B; TTN-AS1, hsa-miR-376b-3p, and TRPM5; and DLX6-AS1, hsa-miR-346, and BIRC7 axes were obtained by constructing the ceRNA networks. Through the immune infiltration analysis, we found that the proportion of CD4 and CD8 T cells was about 20%, and the proportion of fibroblasts and endothelial cells was high. Our findings provide some insights into the mechanisms of RNA interaction in TR-induced right ventricular cardiomyopathy and suggest that lncRNAs are a potential therapeutic target for treating right ventricular myocardial disease induced by TR.

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field.

Targeting NUPR1 for Cancer Treatment: A Risky Endeavor

NUPR1 is a transcription factor that has attracted great attention because of its various roles in cancer. Several studies were carried out to determine its molecular targets and mechanism of action to develop novel therapies against cancer. Here, we shed light on the role of NUPR1 in different types of cancer. NUPR1 regulates a complex network of pathways that may be affected by its silencing, which can cause varying effects. Its role in some types of cancer has been reported but remains incompletely understood, whereas its roles in other types of cancers have not been reported yet. Therefore, targeting NUPR1 for cancer treatment remains challenging and risky.

Autophagy Controls CSL/RBPJκ Stability through a p62/SQSTM1-Dependent Mechanism

Cancer-associated fibroblasts (CAFs) are important at all tumor stages. CSL/RBPJκ suppresses the gene expression program leading to CAF activation and associated metabolic reprogramming, as well as autophagy. Little is known about CSL protein turnover, especially in the tumor microenvironment. We report that, in human dermal fibroblasts (HDFs), conditions inducing autophagy—often found in tumor stroma—down-regulate CSL protein levels but do not affect its mRNA levels. Genetic or pharmacologic targeting of the autophagic machinery blocks CSL down-modulation. Mechanistically, endogenous CSL associates with the autophagy and signaling adaptor p62/SQSTM1, which is required for CSL down-modulation by autophagy. This is functionally significant, because both CSL and p62 levels are lower in skin cancer-derived CAFs, in which autophagy is increased. Increasing cellular CSL levels stabilizes p62 and down-modulates the autophagic process. We reveal here an autophagy-initiated mechanism for CSL down-modulation, which could be targeted for stroma-focused cancer prevention and treatment.

Autophagic conditions are often found in the tumor stroma, where CSL/RBPJκ levels are down-modulated. Goruppi et al. identify a key role for autophagy in the degradation of CSL through a direct interaction with the p62 adaptor. This induces CSL-repressed genes involved in CAF activation and autophagy, linking the two processes.

B. Teles R, Montoya D, O. Scumpia P, Nunes Sarno E, Ochoa MT, Ma F, Pellegrini M, Modlin RL. The cell fate regulator NUPR1 is induced by Mycobacterium leprae via type I interferon in human leprosy

The initial interaction between a microbial pathogen and the host immune response influences the outcome of the battle between the host and the foreign invader. Leprosy, caused by the obligate intracellular pathogen Mycobacterium leprae, provides a model to study relevant human immune responses. Previous studies have adopted a targeted approach to investigate host response to M. leprae infection, focusing on the induction of specific molecules and pathways. By measuring the host transcriptome triggered by M. leprae infection of human macrophages, we were able to detect a host gene signature 24-48 hours after infection characterized by specific innate immune pathways involving the cell fate mechanisms autophagy and apoptosis. The top upstream regulator in the M. leprae-induced gene signature was NUPR1, which is found in the M. leprae-induced cell fate pathways. The induction of NUPR1 by M. leprae was dependent on the production of the type I interferon (IFN), IFN-β. Furthermore, NUPR1 mRNA and protein were upregulated in the skin lesions from patients with the multibacillary form of leprosy. Together, these data indicate that M. leprae induces a cell fate program which includes NUPR1 as part of the host response in the progressive form of leprosy.

Inhibition of ROS/NUPR1-dependent autophagy antagonises repeated cadmium exposure -induced oral squamous cell carcinoma cell migration and invasion

Cadmium (Cd), an established carcinogen, is a risk factor for oral squamous cell carcinoma (OSCC). Macroautophagy/autophagy is proposed to play a pivotal role in Cd-mediated carcinogenic activity. However, the mechanisms underlying Cd-induced autophagy are poorly understood. In the present study, a CAL27 OSCC cell line exposed to 10^-6 M Cd for 8 weeks was used as a model system. Repeated Cd exposure induced significant migration and invasion of CAL27 cells. Furthermore, we showed that Cd increased the autophagic flux in CAL27 cells, as evidenced by the upregulation of LC3-II and the downregulation of P62/SQSTM1. The genetic blocking of autophagy inhibited Cd-induced migration and invasion, indicating a carcinogenic role of autophagy in Cd-treated CAL27 cells. Cd-induced NUPR1 expression, which contributes to lysosomal biogenesis and expression of autophagy-related gene, was found to mechanistically initiate autophagy in CAL27 cells. Of note, NUPR1 shRNA abolished Cd-induced autophagy both in vitro and in vivo. We also found that Cd triggered the generation of MDA in a xenograft tumour model and that N-acetyl-l-cysteine, a reactive oxygen species (ROS) scavenger, abrogated the effects of Cd on NUPR1-dependent autophagy in vivo. Taken together, these results demonstrate that ROS-dependent NUPR1-mediated autophagy plays an important role in repeated Cd exposure -induced cell growth, migration and invasion in OSCC cells.

Deficiency of stress-associated gene Nupr1 increases bone volume by attenuating differentiation of osteoclasts and enhancing differentiation of osteoblasts

Nuclear protein 1 (NUPR1) is a multifunctional stress-induced protein involved in regulating tumorigenesis, apoptosis, and autophagy. Bone homeostasis is maintained by bone-resorbing osteoclasts and bone-forming osteoblasts and osteocytes. We aimed to determine the role of NUPR1 in bone metabolism. Using microcomputed tomography, we found that mice lacking Nupr1 exhibited increased bone volume. Histologic analysis showed that Nupr1 deficiency decreased osteoclast numbers but increased osteoblast numbers and osteoid formation. In vitro culture of bone marrow macrophages showed that receptor activator of NF-κB ligand-induced osteoclastogenesis was down-regulated in Nupr1-deficient mice. In contrast, primary osteoblasts from Nupr1-deficient mice revealed that proliferation of osteoblasts and expression of bone matrix proteins were markedly enhanced. In addition, expression of autophagy-related genes, formation of autophagosomes, and cell survival were up-regulated in Nupr1-deficient osteoblasts. In contract, deletion of Nupr1 reduced the formation of osteocyte cellular projection, which is an indicator of mature osteocytes. Importantly, we found that the expression of sclerostin (Sost), an inhibitor of bone formation, was down-regulated in the osteoblasts and osteocytes of Nupr1-deficient mice. Conversely, Nupr1 overexpression enhanced Sost expression in primary osteoblasts. Collectively, these results indicate that Nupr1 deficiency increases bone volume by attenuating production of Sost and osteoclastogenesis and enhancing differentiation of osteoblasts.-Shiraki, M., Xu, X., Iovanna, J. L., Kukita, T., Hirata, H., Kamohara, A., Kubota, Y., Miyamoto, H., Mawatari, M., Kukita, A. Deficiency of stress-associated gene Nupr1 increases bone volume by attenuating differentiation of osteoclasts and enhancing differentiation of osteoblasts.

Inactivation of NUPR1 promotes cell death by coupling ER-stress responses with necrosis

It was already described that genetic inhibition of NUPR1 induces tumor growth arrest. In this paper we studied the metabolism changes after NUPR1 downregulation in pancreatic cancer cells, which results in a significant decrease of OXPHOS activity with a concomitant lower ATP production which precedes the necrotic cell death. We demonstrated that NUPR1 downregulation induces a mitochondrial failure with a loss of the mitochondrial membrane potential, a strong increase in ROS production and a concomitant relocalization of mitochondria to the vicinity of the endoplasmic reticulum (ER). In addition, the transcriptomic analysis of NUPR1-deficient cells shows a decrease in the expression of some ER stress response-associated genes. Indeed, in ER stressors-treated cells with thapsigargin, brefeldin A or tunicamycin, a greater increase in necrosis and decrease of ATP content was observed in NUPR1-defficent cells. Finally, in vivo experiments, using acute pancreatitis which induces ER stress as well as NUPR1 activation, we observed that NUPR1 expression protects acinar cells from necrosis in mice. Importantly, we also report that the cell death observed after knocking-down NUPR1 expression is completely reversed by incubation with Necrostatin-1, but not by inhibiting caspase activity with Z-VAD-FMK. Altogether, these data enable us to describe a model in which inactivation of NUPR1 in pancreatic cancer cells results in an ER stress that induces a mitochondrial malfunction, a deficient ATP production and, as consequence, the cell death mediated by a programmed necrosis.

A novel role for NUPR1 in the keratinocyte stress response to UV oxidized phospholipids

Ultraviolet light is the dominant environmental oxidative skin stressor and a major skin aging factor. We studied which oxidized phospholipid (OxPL) mediators would be generated in primary human keratinocytes (KC) upon exposure to ultraviolet A light (UVA) and investigated the contribution of OxPL to UVA responses. Mass spectrometric analysis immediately or 24 h post UV stress revealed significant changes in abundance of 173 and 84 lipid species, respectively. We identified known and novel lipid species including known bioactive and also potentially reactive carbonyl containing species. We found indication for selective metabolism and degradation of selected reactive lipids. Exposure to both UVA and to in vitro UVA - oxidized phospholipids activated, on transcriptome and proteome level, NRF2/antioxidant response signaling, lipid metabolizing enzyme expression and unfolded protein response (UPR) signaling. We identified NUPR1 as an upstream regulator of UVA/OxPL transcriptional stress responses and found this protein to be expressed in the epidermis. Silencing of NUPR1 resulted in augmented expression of antioxidant and lipid detoxification genes and disturbed the cell cycle, making it a potential key factor in skin reactive oxygen species (ROS) responses intimately involved in aging and pathology.

The ULK3 Kinase Is Critical for Convergent Control of Cancer-Associated Fibroblast Activation by CSL and GLI

The connection between signaling pathways activating cancer-associated fibroblasts (CAFs) remains to be determined. Metabolic alterations linked to autophagy have also been implicated in CAF activation. CSL/RBPJ, a transcriptional repressor that mediates Notch signaling, suppresses the gene expression program(s), leading to stromal senescence and CAF activation. Deregulated GLI signaling can also contribute to CAF conversion. Here, we report that compromised CSL function depends on GLI activation for conversion of human dermal fibroblasts into CAFs, separately from cellular senescence. Decreased CSL upregulates the expression of the ULK3 kinase, which binds and activates GLI2. Increased ULK3 also induces autophagy, which is unlinked from GLI and CAF activation. ULK3 upregulation occurs in the CAFs of several tumor types, and ULK3 silencing suppresses the tumor-enhancing properties of these cells. Thus, ULK3 links two key signaling pathways involved in CAF conversion and is an attractive target for stroma-focused anti-cancer intervention.

FOXO1/3: Potential suppressors of fibrosis

Fibrosis is a universally age-related disease that involves nearly all organs. It is typically initiated by organic injury and eventually results in organ failure. There are still few effective therapeutic strategy targets for fibrogenesis. Forkhead box proteins O1 and O3 (FOXO1/3) have been shown to have favorable inhibitory effects on fibroblast activation and subsequent extracellular matrix production and can ameliorate fibrosis levels in numerous organs, including the heart, liver, lung, and kidney; they are therefore promising targets for anti-fibrosis therapy. Moreover, we can develop appropriate strategies to make the best use of FOXO1/3's anti-fibrosis properties. The information reviewed here should be significant for understanding the roles of FOXO1/3 in fibrosis and should contribute to the design of further studies related to FOXO1/3 and the fibrotic response and shed light on a potential treatment for fibrosis.

FOXOs in the impaired heart: New therapeutic targets for cardiac diseases

Cardiac diseases have a high morbidity and mortality and affect the global population. Based on recent accumulating evidence, Forkhead box O (FOXOs) play important roles in cardiac diseases. Therefore, a summary of the current literature on the molecular mechanisms and roles of FOXOs in the heart will provide valuable information. In this review, we first briefly introduce the molecular features of FOXOs. Then, we discuss the regulation and cardiac actions of the FOXO pathways. Based on this background, we expand our discussion to the roles of FOXOs in several major cardiac diseases, such as ischemic cardiac diseases, diabetic cardiomyopathy and myocardial hypertrophy. Then, we describe some methodological problems associated with the FOXO gene-modified animal models. Finally, we discuss potential future directions. The information reviewed here may be significant for the design of future studies and may increase the potential of FOXOs as therapeutic targets.

The Role of the Transcription Factor Foxo3 in Hearing Maintenance: Informed Speculation on a New Player in the Cochlea

Molecular genetics has proven to be a powerful approach for understanding early-onset hearing loss. Recent work in late-onset hearing loss uses mouse genetics to identify molecular mechanisms that promote the maintenance of hearing. One such gene, Foxo3, is ontologically involved in preserving mitochondrial function. Significant evidence exists to support the idea that mitochondrial dysfunction is correlated with and can be causal for hearing loss. Foxo3 is also ontologically implicated in driving the circadian cycle, which has recently been shown to influence the molecular response to noise damage. In this review, the molecular framework connecting these cellular processes is discussed in relation to the cellular pathologies observed in human specimens of late-onset hearing loss. In bringing these observations together, the possibility arises that distinct molecular mechanisms work in multiple cell types to preserve hearing. This diversity offers great opportunities to understand and manipulate genetic processes for therapeutic gain.

A liver stress-endocrine nexus promotes metabolic integrity during dietary protein dilution

Dietary protein intake is linked to an increased incidence of type 2 diabetes (T2D). Although dietary protein dilution (DPD) can slow the progression of some aging-related disorders, whether this strategy affects the development and risk for obesity-associated metabolic disease such as T2D is unclear. Here, we determined that DPD in mice and humans increases serum markers of metabolic health. In lean mice, DPD promoted metabolic inefficiency by increasing carbohydrate and fat oxidation. In nutritional and polygenic murine models of obesity, DPD prevented and curtailed the development of impaired glucose homeostasis independently of obesity and food intake. DPD-mediated metabolic inefficiency and improvement of glucose homeostasis were independent of uncoupling protein 1 (UCP1), but required expression of liver-derived fibroblast growth factor 21 (FGF21) in both lean and obese mice. FGF21 expression and secretion as well as the associated metabolic remodeling induced by DPD also required induction of liver-integrated stress response-driven nuclear protein 1 (NUPR1). Insufficiency of select nonessential amino acids (NEAAs) was necessary and adequate for NUPR1 and subsequent FGF21 induction and secretion in hepatocytes in vitro and in vivo. Taken together, these data indicate that DPD promotes improved glucose homeostasis through an NEAA insufficiency-induced liver NUPR1/FGF21 axis.

Gene Expression in Mouse Thyrotrope Adenoma: Transcription Elongation Factor Stimulates Proliferation

Thyrotrope hyperplasia and hypertrophy are common responses to primary hypothyroidism. To understand the genetic regulation of these processes, we studied gene expression changes in the pituitaries of Cga(-/-) mice, which are deficient in the common α-subunit of TSH, LH, and FSH. These mice have thyrotrope hypertrophy and hyperplasia and develop thyrotrope adenoma. We report that cell proliferation is increased, but the expression of most stem cell markers is unchanged. The α-subunit is required for secretion of the glycoprotein hormone β-subunits, and mutants exhibit elevated expression of many genes involved in the unfolded protein response, consistent with dilation and stress of the endoplasmic reticulum. Mutants have elevated expression of transcription factors that are important in thyrotrope function, such as Gata2 and Islet 1, and those that stimulate proliferation, including Nupr1, E2f1, and Etv5. We characterized the expression and function of a novel, overexpressed gene, transcription elongation factor A (SII)-like 5 (Tceal5). Stable expression of Tceal5 in a pituitary progenitor cell line is sufficient to increase cell proliferation. Thus, Tceal5 may act as a proto-oncogene. This study provides a rich resource for comparing pituitary transcriptomes and an analysis of gene expression networks.

Hypoxia suppresses myocardial survival pathway through HIF-1α-IGFBP-3-dependent signaling and enhances cardiomyocyte autophagic and apoptotic effects mainly via FoxO3a-induced BNIP3 expression

The HIF-1α transcriptional factor and the BH-3 only protein BNIP3 are known to play fundamental roles in response to hypoxia. The objective of this research is to investigate the molecular mechanisms and the correlation of HIF-1α, BNIP3 and IGFBP-3 in hypoxia-induced cardiomyocytes injuries. Heart-derived H9c2 cells and neonatal rat ventricular myocytes (NRVMs) were incubated in normoxic or hypoxic conditions. Hypoxia increased HIF-1α expression and activated the downstream BNIP3 and IGFBP-3 thereby triggered mitochondria-dependent apoptosis. Moreover, IGF1R/PI3K/Akt signaling was attenuated by HIF-1α-dependent IGFBP-3 expression to enhance hypoxia-induced apoptosis. Autophagy suppression with 3-methyladenine or siATG5 or siBeclin-1 significantly decreased myocardial apoptosis under hypoxia. Knockdown of FoxO3a or BNIP3 significantly abrogated hypoxia-induced autophagy and mitochondria-dependent apoptosis. Moreover, prolonged-hypoxia induced HIF-1α stimulated BNIP3 and enhanced IGFBP-3 activation to inhibit IGF1R/PI3K/Akt survival pathway and mediate mitochondria-dependent cardiomyocyte apoptosis. HIF-1α and FoxO3a blockage are sufficient to annul the change of excessive hypoxia of hearts.

The transcription factor p8 regulates autophagy during diapause embryo formation in Artemia parthenogenetica

Autophagy is an essential homeostatic process by which cytoplasmic components, including macromolecules and organelles, are degraded by lysosome. Increasing evidence suggests that phosphorylated AMP-activated protein kinase (p-AMPK) and target of rapamycin (TOR) play key roles in the regulation of autophagy. However, the regulation of autophagy in quiescent cells remains unclear, despite the fact that autophagy is known to be critical for normal development, regeneration, and degenerative diseases. Here, crustacean Artemia parthenogenetica was used as a model system because they produced and released encysted embryos that enter a state of obligate dormancy in cell quiescence to withstand various environmental threats. We observed that autophagy was increased before diapause stage but dropped to extremely low level in diapause cysts in Artemia. Western blot analyses indicated that the regulation of autophagy was AMPK/TOR independent during diapause embryo formation. Importantly, the level of p8 (Ar-p8), a stress-inducible transcription cofactor, was elevated at the stage just before diapause and was absent in encysted embryos, indicating that Ar-p8 may regulate autophagy. The results of Ar-p8 knockdown revealed that Ar-p8 regulated autophagy during diapause formation in Artemia. Moreover, we observed that activating transcription factors 4 and 6 (ATF4 and ATF6) responded to Ar-p8-regulated autophagy, indicating that autophagy targeted endoplasmic reticulum (ER) during diapause formation in Artemia. Additionally, AMPK/TOR-independent autophagy was validated in human gastric cancer MKN45 cells overexpressing Ar-p8. The findings presented here may provide insights into the role of p8 in regulating autophagy in quiescent cells.

Transcriptome profiling of the rat retina after optic nerve transection

Glaucoma is a group of eye diseases characterized by alterations in the contour of the optic nerve head (ONH), with corresponding visual field defects and progressive loss of retinal ganglion cells (RGCs). This progressive RGC death is considered to originate in axonal injury caused by compression of the axon bundles in the ONH. However, the molecular pathomechanisms of axonal injury-induced RGC death are not yet well understood. Here, we used RNA sequencing (RNA-seq) to examine transcriptome changes in rat retinas 2 days after optic nerve transection (ONT), and then used computational techniques to predict the resulting alterations in the transcriptional regulatory network. RNA-seq revealed 267 differentially expressed genes after ONT, 218 of which were annotated and 49 unannotated. We also identified differentially expressed transcripts, including potentially novel isoforms. An in silico pathway analysis predicted that CREB1 was the most significant upstream regulator. Thus, this study identified genes and pathways that may be involved in the pathomechanisms of axonal injury. We believe that our data should serve as a valuable resource to understand the molecular processes that define axonal injury-driven RGC death and to discover novel therapeutic targets for glaucoma.

Nupr1/Chop signal axis is involved in mitochondrion-related endothelial cell apoptosis induced by methamphetamine

Methamphetamine (METH) abuse has been a serious global public health problem for decades. Previous studies have shown that METH causes detrimental effects on the nervous and cardiovascular systems. METH-induced cardiovascular toxicity has been, in part, attributed to its destructive effect on vascular endothelial cells. However, the underlying mechanism of METH-caused endothelium disruption has not been investigated systematically. In this study, we identified a novel pathway involved in endothelial cell apoptosis induced by METH. We demonstrated that exposure to METH caused mitochondrial apoptosis in human umbilical vein endothelial cells and rat cardiac microvascular endothelial cells in vitro as well as in rat cardiac endothelial cells in vivo. We found that METH mediated endothelial cell apoptosis through Nupr1–Chop/P53–PUMA/Beclin1 signaling pathway. Specifically, METH exposure increased the expression of Nupr1, Chop, P53 and PUMA. Elevated p53 expression raised up PUMA expression, which initiated mitochondrial apoptosis by downregulating antiapoptotic Bcl-2, followed by upregulation of proapoptotic Bax, resulting in translocation of cytochrome c (cyto c), an apoptogenic factor, from the mitochondria to cytoplasm and activation of caspase-dependent pathways. Interestingly, increased Beclin1, upregulated by Chop, formed a ternary complex with Bcl-2, thereby decreasing the dissociative Bcl-2. As a result, the ratio of dissociative Bcl-2 to Bax was also significantly decreased, which led to translocation of cyto c and initiated more drastic apoptosis. These findings were supported by data showing METH-induced apoptosis was significantly inhibited by silencing Nupr1, Chop or P53, or by PUMA or Beclin1 knockdown. Based on the present data, a novel mechanistic model of METH-induced endothelial cell toxicity is proposed. Collectively, these results highlight that the Nupr1–Chop/P53–PUMA/Beclin1 pathway is essential for mitochondrion-related METH-induced endothelial cell apoptosis and may be a potential therapeutic target for METH-caused cardiovascular toxicity. Future studies using knockout animal models are warranted to substantiate the present findings.

The Transcription Factor p8 Regulates Autophagy in Response to Palmitic Acid Stress via a Mammalian Target of Rapamycin (mTOR)-independent Signaling Pathway

Autophagy is an evolutionarily conserved degradative process that allows cells to maintain homoeostasis in numerous physiological situations. This process also functions as an essential protective response to endoplasmic reticulum (ER) stress, which promotes the removal and degradation of unfolded proteins. However, little is known regarding the mechanism by which autophagy is initiated and regulated in response to ER stress. In this study, different types of autophagy were identified in human gastric cancer MKN45 cells in response to the stress induced by nutrient starvation or lipotoxicity in which the regulation of these pathways is mammalian target of rapamycin (mTOR)-dependent or -independent, respectively. Interestingly, we found that p8, a stress-inducible transcription factor, was enhanced in MKN45 cells treated with palmitic acid to induce lipotoxicity. Furthermore, an increase in autophagy was observed in MKN45 cells stably overexpressing p8 using a lentivirus system, and autophagy induced by palmitic acid was blocked by p8 RNAi compared with the control. Western blotting analyses showed that autophagy was regulated by p8 or mTOR in response to the protein kinase-like endoplasmic reticulum kinase/activating transcription factor 6-mediated ER stress of lipotoxicity or the parkin-mediated mitochondrial stress of nutrient starvation, respectively. Furthermore, our results indicated that autophagy induced by palmitic acid is mTOR-independent, but this autophagy pathway was regulated by p8 via p53- and PKCα-mediated signaling in MKN45 cells. Our findings provide insights into the role of p8 in regulating autophagy induced by the lipotoxic effects of excess fat accumulation in cells.

Expression of p8 in Human Oral Squamous Cell Carcinoma

The present study investigated the expression of p8, a transcription factor upregulated in some human cancers, in oral squamous cell carcinomas (OSCCs). Immunohistochemical analysis of p8 expression was carried out on 20 archived surgical specimens of human OSCCs, and expression correlated with clinical outcome parameters in a retrospective study. Expression of p8 in a number of OSCC cell lines also was investigated by western blot and RT-PCR analyses. p8 was expressed in 80 % (16/20) of the samples with levels of expression exhibiting a significant difference (χ(2) = 8.352, df = 3, p = 0.039) by patient age. Furthermore, greater levels of p8 immunoreactivity was significantly associated with advanced tumor grade (p = 0.008). p8 also was upregulated in OSCC cell lines. p8 is expressed in a significant proportion of OSCCs, and in human OSCC cell lines, suggesting a potential value of p8 as a diagnostic and/prognostic tool for oral cancers.

Genetic inactivation of Nupr1 acts as a dominant suppressor event in a two-hit model of pancreatic carcinogenesis

BACKGROUND

Nuclear protein 1 (Nupr1) is a major factor in the cell stress response required for Kras(G12D)-driven formation of pancreatic intraepithelial neoplastic lesions (PanINs). We evaluated the relevance of Nupr1 in the development of pancreatic cancer.

METHODS

We investigated the role of Nupr1 in pancreatic ductal adenocarcinoma (PDAC) progression beyond PanINs in Pdx1-cre;LSL-Kras(G12D);Ink4a/Arf(fl/fl)(KIC) mice.

RESULTS

Even in the context of the second tumorigenic hit of Ink4a/Arf deletion, Nupr1 deficiency led to suppression of malignant transformation involving caspase 3 activation in premalignant cells of KIC pancreas. Only half of Nupr1-deficient;KIC mice achieved PDAC development, and incident cases survived longer than Nupr1(wt);KIC mice. This was associated with the development of well-differentiated PDACs in Nupr1-deficient;KIC mice, which displayed enrichment of genes characteristic of the recently identified human classical PDAC subtype. Nupr1-deficient;KIC PDACs also shared with human classical PDACs the overexpression of the Kras-activation gene signature. In contrast, Nupr1(wt);KIC mice developed invasive PDACs with enriched gene signature of human quasi-mesenchymal (QM) PDACs. Cells derived from Nupr1-deficient;KIC PDACs growth in an anchorage-independent manner in vitro had higher aldehyde dehydrogenase activity and overexpressed nanog, Oct-4 and Sox2 transcripts compared with Nupr1(wt);KIC cells. Moreover, Nupr1-deficient and Nurpr1(wt);KIC cells differed in their sensitivity to the nucleoside analogues Ly101-4b and WJQ63. Together, these findings show the pivotal role of Nupr1 in both the initiation and late stages of PDAC in vivo, with a potential impact on PDAC cell stemness.

CONCLUSIONS

According to Nupr1 status, KIC mice develop tumours that phenocopy human classical or QM-PDAC, respectively, and present differential drug sensitivity, thus becoming attractive models for preclinical drug trials.

Autophagy: regulation and role in development

Autophagy is an evolutionarily conserved cellular process through which long-lived proteins and damaged organelles are recycled to maintain energy homeostasis. These proteins and organelles are sequestered into a double-membrane structure, or autophagosome, which subsequently fuses with a lysosome in order to degrade the cargo. Although originally classified as a type of programmed cell death, autophagy is more widely viewed as a basic cell survival mechanism to combat environmental stressors. Autophagy genes were initially identified in yeast and were found to be necessary to circumvent nutrient stress and starvation. Subsequent elucidation of mammalian gene counterparts has highlighted the importance of this process to normal development. This review provides an overview of autophagy, the types of autophagy, its regulation and its known impact on development gleaned primarily from murine models.

Expression and roles of As-NUPR1 protein from Artemia sinica during embryo development and in response to salinity stress

As-NUPR1, a stress-related protein, plays an important role in post-diapause during embryonic development in the brine shrimp Artemia sinica. In the present study, successful expression of As-NUPR1 from the cDNA sequence isolated from A. sinica was demonstrated using a prokaryotic expression system. The recombinant protein consisted of 132 amino acids with a molecular weight of 15 kDa, and a predicted isoelectric point of 7.17. As-NUPR1 polyclonal antibodies were prepared by immunization of Balb/c mice with purified recombinant As-NUPR1 protein as an antigen, and immunological studies were carried out. Expression of As-NUPR1 during different developmental stages of the embryo and in response to salinity stress was analyzed in A. sinica using Western blots. The experimental results showed that the expression of As-NUPR1 is widely distributed at different developmental stages in A. sinica, and there was no tissue or organ specificity. Expression of As-NUPR1 decreased gradually during the diapause termination stage of embryo development, after which there was a general increase in expression after breaking the shell. In addition, As-NUPR1 expression was highly upregulated under conditions of high salinity. These results suggest that the As-NUPR1 protein is a stress-related protein that plays a role in protecting embryos from high salt damage in different embryonic developmental stages, especially during the post-diapause period.

The autophagy-related gene 14 (Atg14) is regulated by forkhead box O transcription factors and circadian rhythms and plays a critical role in hepatic autophagy and lipid metabolism

Autophagy plays a critical role in cell survival from prolonged starvation and recycling of aggregated proteins and damaged organelles. One of the essential genes involved in the autophagic initiation is autophagy-related 14 (Atg14), also called Barkor for Beclin 1-associated autophagy-related key regulator. Although its crucial role in the autophagic process has been reported, the gene regulation of Atg14 and its metabolic functions remain unclear. In this work we have identified that the Atg14 gene is regulated by forkhead box O (FoxO) transcription factors and circadian rhythms in the mouse liver. Luciferase reporter analyses and chromatin immunoprecipitation assays have revealed well conserved cis-elements for FoxOs and Clock/Bmal1 in the proximal promoter of the Atg14 gene. To examine the functions of hepatic Atg14, we have performed the gene knockdown and overexpression in the mouse livers. Remarkably, knockdown of Atg14 leads to elevated levels of triglycerides in the liver and serum as well. Conversely, overexpression of Atg14 improves hypertriglyceridemia in both high fat diet-treated wild-type mice and FoxO1/3/4 liver-specific knock-out mice. In summary, our data suggest that Atg14 is a new target gene of FoxOs and the core clock machinery, and this gene plays an important role in hepatic lipid metabolism.

Lentivirus-mediated RNAi knockdown of NUPR1 inhibits human nonsmall cell lung cancer growth in vitro and in vivo

NUPR1 (nuclear protein 1) was found to play a key role in the development of several malignancies including pancreas, breast, and prostate cancers. However, the functional role of NUPR1 in nonsmall cell lung cancer (NSCLC) progression and development is little known. Here, lentivirus-mediated small interfering RNA (siRNA) was employed to downregulate endogenous NUPR1 expression to study the function of NUPR1 in growth of nonsmall cell lung cancer. A lentivirus-mediated RNAi technology was used to specifically knock down the expression of NUPR1 in H1299 cells. Quantitative real-time reverse transcriptase polymerase chain reaction, flow cytometry, western blot and cell count assays were studied to characterize NUPR1 expression in vitro. Furthermore, nonsmall cell lung cancer xenograft models in nude mice were established to investigate whether knockdown of NUPR1 reduces the tumor growth in vivo. We found that downregulation of NUPR1 expression significantly inhibited nonsmall cell lung cancer H1299 cells proliferation and colony formation in vitro. Moreover, the specific downregulation of NUPR1 arrested cells in G0 phase of cell cycle and increased apoptosis rate. Silencing of NUPR1 also suppressed tumor growth by tail vein injection of lentivirus encoded shRNA against NUPR1 in vivo. Our findings revealed that the NUPR1 gene represents a promising target for gene silencing therapy in nonsmall cell lung cancer.

Nupr1-aurora kinase A pathway provides protection against metabolic stress-mediated autophagic-associated cell death

PURPOSE

The limited supply of oxygen and nutrients is thought to result in rigorous selection of cells that will eventually form the tumor.

EXPERIMENTAL DESIGN

Nupr1 expression pattern was analyzed in human tissue microarray (TMA) and correlated with survival time of the patient. Microarray analysis was conducted on MiaPaCa2 cells subjected to metabolic stress in Nupr1-silenced conditions. DNA repair and cell cycle-associated gene expression was confirmed by real-time quantitative PCR (qRT-PCR). Nupr1 and AURKA protective role were analyzed using RNA interference (RNAi) silencing or overexpression. DNA damage and autophagy were analyzed by Western blot analysis and immunofluorescence.

RESULTS

We showed that both Nupr1 and HIF1α are coexpressed in human pancreatic ductal adenocarcinoma (PDAC) samples and negatively correlate with survival time. PDAC-derived cells submitted to hypoxia and/or glucose starvation induce DNA damage-dependent cell death concomitantly to the overexpression of stress protein Nupr1. Affymetrix-based transcriptoma analysis reveals that Nupr1 knockdown enhances DNA damage and alters the expression of several genes involved in DNA repair and cell-cycle progression. Expression of some of these genes is common to hypoxia and glucose starvation, such as Aurka gene, suggesting that Nupr1 overexpression counteracts the transcriptional changes occurring under metabolic stress. The molecular mechanism by which hypoxia and glucose starvation induce cell death involves autophagy-associated, but not caspase-dependent, cell death. Finally, we have found that AURKA expression is partially regulated by Nupr1 and plays a major role in this response.

CONCLUSIONS

Our data reveal that Nupr1 is involved in a defense mechanism that promotes pancreatic cancer cell survival when exposed to metabolic stress.

Cytoplasmic translocation of p21 mediates NUPR1-induced chemoresistance: NUPR1 and p21 in chemoresistance

The expression of Nuclear Protein 1 (NUPR1) is associated with chemoresistance in multiple malignancies. We previously reported that NUPR1 functions as a transcriptional cofactor for the p300-p53 complex and transcriptionally regulates p21 expression. In the present study we investigated the activity of NUPR1 in p53-deficient, triple-negative, inflammatory SUM159 breast cancer cells. Our studies reveal that NUPR1 confers growth benefit and chemoresistance by causing Akt-mediated phosphorylation and subsequent cytoplasmic re-localization of p21 and activation of the anti-apoptotic Bcl-xL protein. Our findings elucidate a NUPR1-PI-3-K/Akt-phospho-p21 axis that functions in p53-negative, inflammatory breast cancer cells to enhance chemoresistance in breast cancer.

Homotypic cell cannibalism, a cell-death process regulated by the nuclear protein 1, opposes to metastasis in pancreatic cancer

Pancreatic adenocarcinoma (PDAC) is an extremely deadly disease for which all treatments available have failed to improve life expectancy significantly. This may be explained by the high metastatic potential of PDAC cells, which results from their dedifferentiation towards a mesenchymal phenotype. Some PDAC present cell-in-cell structures whose origin and significance are currently unknown. We show here that cell-in-cells form after homotypic cell cannibalism (HoCC). We found PDAC patients whose tumours display HoCC develop less metastasis than those without. In vitro, HoCC was promoted by inactivation of the nuclear protein 1 (Nupr1), and was enhanced by treatment with transforming growth factor β. HoCC ends with death of PDAC cells, consistent with a metastasis suppressor role for this phenomenon. Hence, our data indicates a protective role for HoCC in PDAC and identifies Nupr1 as a molecular regulator of this process.

Spatial expression patterns of autophagy genes in the eye lens and induction of autophagy in lens cells

PURPOSE

Mutation of the autophagy gene FYVE (named after the four cysteine-rich proteins: Fab 1 [yeast orthologue of PIKfyve], YOTB, Vac 1 [vesicle transport protein], and EEA1) and coiled coil containing 1 (fyco1) causes human cataract suggesting a role for autophagy in lens function. Here, we analyzed the range and spatial expression patterns of lens autophagy genes and we evaluated whether autophagy could be induced in lens cells exposed to stress.

METHODS

Autophagy gene expression levels and their spatial distribution patterns were evaluated between microdissected human lens epithelium and fibers at the mRNA and protein levels by microarray data analysis, real-time PCR and western blot analysis. Selected autophagy protein spatial expression patterns were also examined in newborn mouse lenses by immunohistochemistry. The autophagosomal content of cultured human lens epithelial cells was determined by counting the number of microtubule-associated protein 1 light chain 3B (LC3B)-positive puncta in cells cultured in the presence or absence of serum.

RESULTS

A total of 42 autophagy genes were detected as being expressed by human lens epithelium and fibers. The autophagosomal markers LC3B and FYCO1 were detected throughout the newborn mouse lens. Consistently, the autophagy active form of LC3B (LC3B II) was detected in microdissected human lens fibers. An increased number of LC3B-positive puncta was detected in cultured lens cells upon serum starvation suggesting induction of autophagy in lens cells under stress conditions.

CONCLUSIONS

The data provide evidence that autophagy is an important component for the function of lens epithelial and fiber cells. The data are consistent with the notion that disruption of lens autophagy through mutation or inactivation of specific autophagy proteins could lead to loss of lens resistance to stress and/or loss of lens differentiation resulting in cataract formation.

A butyrolactone derivative suppressed lipopolysaccharide-induced autophagic injury through inhibiting the autoregulatory loop of p8 and p53 in vascular endothelial cells

Lipopolysaccharide (LPS)-induced vascular endothelial cell (VEC) dysfunction is an important contributing factor in vascular diseases. Recently, we found that LPS impaired VEC by inducing autophagy. Our previous researches showed that a butyrolactone derivative, 3-benzyl-5-((2-nitrophenoxy) methyl)-dihydrofuran-2(3H)-one (3BDO) selectively protected VEC function. The objective of the present study is to investigate whether and how 3BDO inhibits LPS-induced VEC autophagic injury. Our results showed that LPS induced autophagy and led to increase of reactive oxygen species (ROS) and decrease of mitochondrial membrane potential (MMP) in Human umbilical vein vascular endothelial cells (HUVECs). Furthermore, LPS significantly increased p8 and p53 protein levels and the nuclear translocation of p53. All of these effects of LPS on HUVECs were strongly inhibited by 3BDO. Importantly, the ROS scavenger N-acetylcysteine (NAC) could inhibited LPS-induced autophagy and knockdown of p8 by RNA interference inhibited the autophagy, p53 protein level increase, the translocation of p53 into nuclei and the ROS level increase induced by LPS in HUVECs. The data suggested that 3BDO inhibited LPS-induced autophagy in HUVECs through inhibiting the ROS overproduction, the increase of p8 and p53 expression and the nuclear translocation of p53. Our findings provide a potential tool for understanding the mechanism underlying LPS-induced autophagy in HUVECs and open the door to a novel therapeutic drug for LPS-induced vascular diseases.

A comprehensive glossary of autophagy-related molecules and processes (2nd edition)

The study of autophagy is rapidly expanding, and our knowledge of the molecular mechanism and its connections to a wide range of physiological processes has increased substantially in the past decade. The vocabulary associated with autophagy has grown concomitantly. In fact, it is difficult for readers--even those who work in the field--to keep up with the ever-expanding terminology associated with the various autophagy-related processes. Accordingly, we have developed a comprehensive glossary of autophagy-related terms that is meant to provide a quick reference for researchers who need a brief reminder of the regulatory effects of transcription factors and chemical agents that induce or inhibit autophagy, the function of the autophagy-related proteins, and the roles of accessory components and structures that are associated with autophagy.

Decreased metalloprotease 9 induction, cardiac fibrosis, and higher autophagy after pressure overload in mice lacking the transcriptional regulator p8

Left ventricular remodeling, including the deposition of excess extracellular matrix, is key to the pathogenesis of heart failure. The stress-inducible transcriptional regulator p8 is increased in failing human hearts and is required both for agonist-stimulated cardiomyocyte hypertrophy and for cardiac fibroblasts matrix metalloprotease-9 (MMP9) induction. In the heart, upregulation of autophagy is an adaptive response to stress and plays a causative role in cardiomyopathies. We have recently shown that p8 ablation in cardiac cells upregulates autophagy and that, in vivo, loss of p8 results in a decrease of cardiac function. Here we investigated the effects of p8 genetic deletion in mediating adverse myocardial remodeling. Unstressed p8-/- mouse hearts manifested complex alterations in the expression of fibrosis markers. In addition, these mice displayed elevated autophagy and apoptosis compared with p8+/+ mice. Transverse aortic constriction (TAC) induced left ventricular p8 expression in p8+/+ mice. Pressure overload caused left ventricular remodeling in both genotypes, however, p8-/- mice showed less cardiac fibrosis induction. Consistent with this, although MMP9 induction was attenuated in the p8-/- mice, induction of MMP2 and MMP3 were strikingly upregulated while TIMP2 was downregulated. Left ventricular autophagy increased after TAC and was significantly higher in the p8-/- mice. Thus p8-deletion results in reduced collagen fibrosis after TAC, but in turn, is associated with a detrimental higher increase in autophagy. These findings suggest a role for p8 in regulating in vivo key signaling pathways involved in the pathogenesis of heart failure.

Transcription factor TEAD4 regulates expression of myogenin and the unfolded protein response genes during C2C12 cell differentiation

The TEAD (1-4) transcription factors comprise the conserved TEA/ATTS DNA-binding domain recognising the MCAT element in the promoters of muscle-specific genes. Despite extensive genetic analysis, the function of TEAD factors in muscle differentiation has proved elusive due to redundancy among the family members. Expression of the TEA/ATTS DNA-binding domain that acts as a dominant negative repressor of TEAD factors in C2C12 myoblasts inhibits their differentiation, whereas selective shRNA knockdown of TEAD4 results in abnormal differentiation characterised by the formation of shortened myotubes. Chromatin immunoprecipitation coupled to array hybridisation shows that TEAD4 occupies 867 promoters including those of myogenic miRNAs. We show that TEAD factors directly induce Myogenin, CDKN1A and Caveolin 3 expression to promote myoblast differentiation. RNA-seq identifies a set of genes whose expression is strongly reduced upon TEAD4 knockdown among which are structural and regulatory proteins and those required for the unfolded protein response. In contrast, TEAD4 represses expression of the growth factor CTGF (connective tissue growth factor) to promote differentiation. Together these results show that TEAD factor activity is essential for normal C2C12 cell differentiation and suggest a role for TEAD4 in regulating expression of the unfolded protein response genes.

Nupr1: the Swiss-knife of cancer

Nupr1 is a small, highly basic and loosely folded multifunctional protein whose expression is induced by several stresses. Its relation to cancer was first suggested by its overexpression in several human malignancies and the association of its expression with breast cancer metastasis. Accordingly, Nupr1 is structurally related to the high-mobility group (HMG) of transcriptional regulators, which play a key role in the stress response and in cancer progression. Nupr1 interacts with numerous partners to regulate cell cycle, programmed cell death, autophagy, chromatin accessibility, and transcription, and its expression is required for regulation of TGFβ activity. Pleiotropic functions accomplished by Nupr1 depend on its molecular partners, its location into the cell, its expression level and on the cell-type. Nupr1 might be a new drug-targetable protein whose blockade would prevent cancer progression and metastasis development.

Mechanisms and biology of B-cell leukemia/lymphoma 2/adenovirus E1B interacting protein 3 and Nip-like protein X

B-cell leukemia/lymphoma 2 (BCL-2)/adenovirus E1B interacting protein 3 (BNIP3) and Nip-like protein X (NIX) are atypical BCL-2 homology domain 3-only proteins involved in cell death, autophagy, and programmed mitochondrial clearance. BNIP3 and NIX cause cell death by targeting mitochondria, directly through BCL-2-associated X protein- or BCL-2-antagonist/killer-dependent mechanisms, or indirectly through an effect on calcium stores in the endoplasmic reticulum. BNIP3 and NIX also induce autophagy through an effect on mitochondrial reactive oxygen species production, or by releasing Beclin 1 from inhibitory interactions with antiapoptotic BCL-2 family proteins. BNIP3 downregulates mitochondrial mass in hypoxic cells, whereas NIX is required for mitochondrial elimination during erythroid development. BNIP3 and NIX have an emerging role in human health. Cell death mediated by BNIP3 and NIX is implicated in heart disease and ischemic injury. Cancer progression is linked to loss of the prodeath function of BNIP3, but also to induction of its prosurvival activity. Finally, BNIP3 and NIX are implicated in mitochondrial quality control, which is important in aging and degenerative disease. Elucidation of the mechanisms by which BNIP3 and NIX regulate cell death, autophagy, and mitochondrial clearance may lead to treatments for these conditions.