C/EBP homologous protein-10 (CHOP-10) limits postnatal neovascularization through control of endothelial nitric oxide synthase gene expression

Diallyl Trisulfide Attenuates Ischemia-Reperfusion-Induced ER Stress and Kidney Dysfunction in Aged Female Mice

Ischemia-reperfusion injury (IRI) is a common cause of acute kidney injury (AKI) in the aging population. Gender studies show that aging is associated with loss of protection from AKI in the female population. While ER stress contributes to IRI-induced AKI in the young, ER regulation during IR in the aged kidney is unclear. Because current evidence suggests hydrogen sulfide (H2S) modulates ER stress, we investigated whether exogenous supplementation of diallyl trisulfide (DATS), an H2S donor, mitigates AKI in aged female kidneys. Wild-type (WT, C57BL/6J) mice aged 75-78 weeks were treated with or without DATS before and after renal IRI. IRI increased ER stress proteins, inflammation, and fibrosis markers in the IRI kidney compared to the control. DATS mitigated ER stress, and reduced inflammation and fibrosis markers in the IRI kidney. Further, IRI kidneys demonstrated reduced blood flow, vascularity, angiogenesis, increased resistive index (RI), and reduced function. DATS treatment upregulated PI3K, AKT, p-mTOR, and pMAPK signaling to stimulate angiogenesis, which improved vascular density, blood flow, and renal function. Together, our results suggest that DATS rescues the aged female kidney IRI by modulating ER stress and upregulation of angiogenesis.

Role of C/EBP Homologous Protein in Vascular Stenosis After Carotid Artery Injury

The study aims to explore the fluctuating expression of C/EBP Homologous Protein (CHOP) following rat carotid artery injury and its central role in vascular stenosis. Using in vivo rat carotid artery injury models and in vitro ischemia and hypoxia cell models employing human aortic endothelial cells (HAECs) and vascular smooth muscle cells (T/G HA-VSMCs), a comprehensive investigative framework was established. Histological analysis confirmed intimal hyperplasia in rat models. CHOP expression in vascular tissues was assessed using Western blot and immunohistochemical staining, and its presence in HAECs and T/G HA-VSMCs was determined through RT-PCR and Western blot. The study evaluated HAEC apoptosis, inflammatory cytokine secretion, cell proliferation, and T/G HA-VSMCs migration through Western blot, ELISA, CCK8, and Transwell migration assays. The rat carotid artery injury model revealed substantial fibrous plaque formation and vascular stenosis, resulting in an increased intimal area and plaque-to-lumen area ratio. Notably, CHOP is markedly elevated in vessels of the carotid artery injury model compared to normal vessels. Atorvastatin effectively mitigated vascular stenosis and suppresses CHOP protein expression. In HAECs, ischemia and hypoxia-induced CHOP upregulation, along with heightened TNFα, IL-6, caspase3, and caspase8 levels, while reducing cell proliferation. Atorvastatin demonstrated a dose-dependent suppression of CHOP expression in HAECs. Downregulation of CHOP or atorvastatin treatment led to reduced IL-6 and TNFα secretion, coupled with augmented cell proliferation. Similarly, ischemia and hypoxia conditions increased CHOP expression in T/G HA-VSMCs, which was concentration-dependently inhibited by atorvastatin. Furthermore, significantly increased MMP-9 and MMP-2 concentrations in the cell culture supernatant correlated with enhanced T/G HA-VSMCs migration. However, interventions targeting CHOP downregulation and atorvastatin usage curtailed MMP-9 and MMP-2 secretion and suppressed cell migration. In conclusion, CHOP plays a crucial role in endothelial injury, proliferation, and VSMCs migration during carotid artery injury, serving as a pivotal regulator in post-injury fibrous plaque formation and vascular remodeling. Statins emerge as protectors of endothelial cells, restraining VSMCs migration by modulating CHOP expression.

Biology and therapeutic targeting of vascular endothelial growth factor A

The formation of new blood vessels, called angiogenesis, is an essential pathophysiological process in which several families of regulators have been implicated. Among these, vascular endothelial growth factor A (VEGFA; also known as VEGF) and its two tyrosine kinase receptors, VEGFR1 and VEGFR2, represent a key signalling pathway mediating physiological angiogenesis and are also major therapeutic targets. VEGFA is a member of the gene family that includes VEGFB, VEGFC, VEGFD and placental growth factor (PLGF). Three decades after its initial isolation and cloning, VEGFA is arguably the most extensively investigated signalling system in angiogenesis. Although many mediators of angiogenesis have been identified, including members of the FGF family, angiopoietins, TGFβ and sphingosine 1-phosphate, all current FDA-approved anti-angiogenic drugs target the VEGF pathway. Anti-VEGF agents are widely used in oncology and, in combination with chemotherapy or immunotherapy, are now the standard of care in multiple malignancies. Anti-VEGF drugs have also revolutionized the treatment of neovascular eye disorders such as age-related macular degeneration and ischaemic retinal disorders. In this Review, we emphasize the molecular, structural and cellular basis of VEGFA action as well as recent findings illustrating unexpected interactions with other pathways and provocative reports on the role of VEGFA in regenerative medicine. We also discuss clinical and translational aspects of VEGFA. Given the crucial role that VEGFA plays in regulating angiogenesis in health and disease, this molecule is largely the focus of this Review.

Dual RNase activity of IRE1 as a target for anticancer therapies

The unfolded protein response (UPR) is a cellular mechanism that protects cells during stress conditions in which there is an accumulation of misfolded proteins in the endoplasmic reticulum (ER). UPR activates three signaling pathways that function to alleviate stress conditions and promote cellular homeostasis and cell survival. During unmitigated stress conditions, however, UPR activation signaling changes to promote cell death through apoptosis. Interestingly, cancer cells take advantage of this pathway to facilitate survival and avoid apoptosis even during prolonged cell stress conditions. Here, we discuss different signaling pathways associated with UPR and focus specifically on one of the ER signaling pathways activated during UPR, inositol-requiring enzyme 1α (IRE1). The rationale is that the IRE1 pathway is associated with cell fate decisions and recognized as a promising target for cancer therapeutics. Here we discuss IRE1 inhibitors and how they might prove to be an effective cancer therapeutic.

Emerging roles of endoplasmic reticulum stress in the cellular plasticity of cancer cells

Cellular plasticity is a well-known dynamic feature of tumor cells that endows tumors with heterogeneity and therapeutic resistance and alters their invasion-metastasis progression, stemness, and drug sensitivity, thereby posing a major challenge to cancer therapy. It is becoming increasingly clear that endoplasmic reticulum (ER) stress is a hallmark of cancer. The dysregulated expression of ER stress sensors and the activation of downstream signaling pathways play a role in the regulation of tumor progression and cellular response to various challenges. Moreover, mounting evidence implicates ER stress in the regulation of cancer cell plasticity, including epithelial-mesenchymal plasticity, drug resistance phenotype, cancer stem cell phenotype, and vasculogenic mimicry phenotype plasticity. ER stress influences several malignant characteristics of tumor cells, including epithelial-to-mesenchymal transition (EMT), stem cell maintenance, angiogenic function, and tumor cell sensitivity to targeted therapy. The emerging links between ER stress and cancer cell plasticity that are implicated in tumor progression and chemoresistance are discussed in this review, which may aid in formulating strategies to target ER stress and cancer cell plasticity in anticancer treatments.

The Role of the Hypoxia-Related Unfolded Protein Response (UPR) in the Tumor Microenvironment

Despite our understanding of the unfolded protein response (UPR) pathways, the crosstalk between the UPR and the complex signaling networks that different cancers utilize for cell survival remains to be, in most cases, a difficult research barrier. A major problem is the constant variability of different cancer types and the different stages of cancer as well as the complexity of the tumor microenvironments (TME). This complexity often leads to apparently contradictory results. Furthermore, the majority of the studies that have been conducted have utilized two-dimensional in vitro cultures of cancer cells that were exposed to continuous hypoxia, and this approach may not mimic the dynamic and cyclic conditions that are found in solid tumors. Here, we discuss the role of intermittent hypoxia, one of inducers of the UPR in the cellular component of TME, and the way in which intermittent hypoxia induces high levels of reactive oxygen species, the activation of the UPR, and the way in which cancer cells modulate the UPR to aid in their survival. Although the past decade has resulted in defining the complex, novel non-coding RNA-based regulatory networks that modulate the means by which hypoxia influences the UPR, we are now just to beginning to understand some of the connections between hypoxia, the UPR, and the TME.

Exercise-induced angiogenesis is dependent on metabolically primed ATF3/4+ endothelial cells

Exercise is a powerful driver of physiological angiogenesis during adulthood, but the mechanisms of exercise-induced vascular expansion are poorly understood. We explored endothelial heterogeneity in skeletal muscle and identified two capillary muscle endothelial cell (mEC) populations that are characterized by differential expression of ATF3/4. Spatial mapping showed that ATF3/4⁺ mECs are enriched in red oxidative muscle areas while ATF3/4^low ECs lie adjacent to white glycolytic fibers. In vitro and in vivo experiments revealed that red ATF3/4⁺ mECs are more angiogenic when compared with white ATF3/4^low mECs. Mechanistically, ATF3/4 in mECs control genes involved in amino acid uptake and metabolism and metabolically prime red (ATF3/4⁺) mECs for angiogenesis. As a consequence, supplementation of non-essential amino acids and overexpression of ATF4 increased proliferation of white mECs. Finally, deleting Atf4 in ECs impaired exercise-induced angiogenesis. Our findings illustrate that spatial metabolic angiodiversity determines the angiogenic potential of muscle ECs.

Redox and Inflammatory Signaling, the Unfolded Protein Response, and the Pathogenesis of Pulmonary Hypertension

Protein folding overload and oxidative stress disrupt endoplasmic reticulum (ER) homeostasis, generating reactive oxygen species (ROS) and activating the unfolded protein response (UPR). The altered ER redox state induces further ROS production through UPR signaling that balances the cell fates of survival and apoptosis, contributing to pulmonary microvascular inflammation and dysfunction and driving the development of pulmonary hypertension (PH). UPR-induced ROS production through ER calcium release along with NADPH oxidase activity results in endothelial injury and smooth muscle cell (SMC) proliferation. ROS and calcium signaling also promote endothelial nitric oxide (NO) synthase (eNOS) uncoupling, decreasing NO production and increasing vascular resistance through persistent vasoconstriction and SMC proliferation. C/EBP-homologous protein further inhibits eNOS, interfering with endothelial function. UPR-induced NF-κB activity regulates inflammatory processes in lung tissue and contributes to pulmonary vascular remodeling. Conversely, UPR-activated nuclear factor erythroid 2-related factor 2-mediated antioxidant signaling through heme oxygenase 1 attenuates inflammatory cytokine levels and protects against vascular SMC proliferation. A mutation in the bone morphogenic protein type 2 receptor (BMPR2) gene causes misfolded BMPR2 protein accumulation in the ER, implicating the UPR in familial pulmonary arterial hypertension pathogenesis. Altogether, there is substantial evidence that redox and inflammatory signaling associated with UPR activation is critical in PH pathogenesis.

Clopidogrel-Induced Gastric Injury in Rats is Attenuated by Stable Gastric Pentadecapeptide BPC 157

Aim

Although Clopidogrel is safe in healthy volunteers, it can induce recurrence of gastric ulcers in high-risk patients. Here, we investigated the protective effect of the natural product, stable gastric pentadecapeptide 157 (BPC 157) on Clopidogrel-induced gastric injury.

Methods

We used acetic acid to induce gastric ulcer in Sprague Dawley rats. Clopidogrel alone or in combination with BPC 157 or L-NAME (nitric oxide system blockade) were administered after healing of acetic acid-induced ulcer. One percent methylcellulose solution was used as control. Ulcer recurrence rate and the ulcer index were compared between these groups. Gastric mucosal apoptosis rate, microscopic inflammation activity and angiogenesis markers vascular endothelial growth factor A (VEGF-A) and CD34 were examined by TUNEL, histological evaluations (HE) and immunohistochemistry (IHC). Pathways involved, expressions of endoplasmic reticulum (ER) stress apoptosis marker CHOP, angiogenic markers VEGF-A and its receptor VEGFR1, and endothelial NO synthase (eNOS) were all analyzed by Western blot.

Results

This study indicated that Clopidogrel significantly induced the gastric ulcers recurrence, severe inflammation and ER stress related apoptosis of the gastric mucosa, suppressed the synthesis of angiogenic markers and eNOS. Furthermore, Clopidrogel intervention resulted in the activation of protein kinase B (AKT) and p38 mitogen-activated protein kinase (p38/MAPK). BPC 157 attenuated the gastric mucosal damage caused by Clopidogrel and reversed these molecular effects. However, NO blockade L-NAME weakened the protective effect and thus the molecular effects of BPC 157 on gastric mucosa.

Conclusion

In conclusion, these results suggest that BPC 157 inhibited Clopidogrel-induced gastric mucosa injury partially by inhibition of gastric mucosa cell ER stress-mediated apoptosis and inflammation, and promoting gastric mucosa angiogenesis via VEGF-A/VEGFR1 mediated-AKT/p38/MAPK signaling pathways.

Unfolded protein response (UPR) integrated signaling networks determine cell fate during hypoxia

During hypoxic conditions, cells undergo critical adaptive responses that include the up-regulation of hypoxia-inducible proteins (HIFs) and the induction of the unfolded protein response (UPR). While their induced signaling pathways have many distinct targets, there are some important connections as well. Despite the extensive studies on both of these signaling pathways, the exact mechanisms involved that determine survival versus apoptosis remain largely unexplained and therefore beyond therapeutic control. Here we discuss the complex relationship between the HIF and UPR signaling pathways and the importance of understanding how these pathways differ between normal and cancer cell models.

Morin supplementation modulates PERK branch of UPR and mitigates 1,2-dimethylhydrazine-induced angiogenesis and oxidative stress in the colon of experimental rats

Angiogenesis, disturbance in redox homeostasis, and deregulated redox signaling are considered as common hallmarks of cancer progression and chemo resistance. In this context, PERK (protein kinase PKR-like ER kinase) branch of the unfolded protein response (UPR), an adaptive mechanism triggered by endoplasmic reticulum (ER) stress to cope with protein misfolding and perturbed proteostasis, has shown to regulate angiogenesis and oxidative stress. This study aimed to investigate the impact of morin, a poly phenolic compound from the family of Moraceae on PERK-Nrf2-VEGF axis in experimental rats challenged with the colon specific procarcinogen 1,2-dimethylhydrazine (DMH). Male albino Wistar rats were randomized into four groups (n = 6) viz., control, morin control, DMH control, and DMH administered rats treated with morin. Immunohistochemical analysis of colonic cross-section revealed that DMH alone administered rats showed significantly increased expression of Nrf2 predominantly in the cytoplasm. Angiogenic growth factors viz., VEGF, PDGF, and bFGF are also shown to be increased in the DMH alone administered tumor bearing rats as compared to control. Significant downregulation was also observed in the downstream targets of Nrf2 such as hemeoxygenase 1 (HO1), glutathione peroxidase 2 (GPX2), thioredoxin (TRXN), glutathione S transferase (GST), and uridine glucuronyl transferase (UGT) as evidenced by the qPCR analysis. Immunoblot analysis revealed that onset of oxidative stress and angiogenesis in the colon of DMH alone administered rats were due to downregulation of pPERK along with its downstream targets such as peIF2α and CHOP. Supplementation of morin reversed the DMH-induced alterations and suppresses oxidative stress and angiogenesis via PERK phosphorylation.

Endoplasmic reticulum stress and pulmonary hypertension

Pulmonary hypertension is a fatal disease of which pulmonary vasculopathy is the main pathological feature resulting in the mean pulmonary arterial pressure higher than 25 mmHg. Moreover, pulmonary hypertension remains a tough problem with unclear molecular mechanisms. There have been dozens of studies about endoplasmic reticulum stress during the onset of pulmonary hypertension in patients, suggesting that endoplasmic reticulum stress may have a critical effect on the pathogenesis of pulmonary hypertension. The review aims to summarize the rationale to elucidate the role of endoplasmic reticulum stress in pulmonary hypertension. Started by reviewing the mechanisms responsible for the unfolded protein response following endoplasmic reticulum stress, the potential link between endoplasmic reticulum stress and pulmonary hypertension were introduced, and the contributions of endoplasmic reticulum stress to different vascular cells, mitochondria, and inflammation were described, and finally the potential therapies of attenuating endoplasmic reticulum stress for pulmonary hypertension were discussed.

Tunicamycin-induced photoreceptor atrophy precedes degeneration of retinal capillaries with minimal effects on retinal ganglion and pigment epithelium cells

Endoplasmic reticulum (ER) stress is recognized as a contributing factor to various ocular neurovascular pathologies including retinitis pigmentosa, glaucoma, and diabetic retinopathy (DR). ER stress in particular is implicated in the development of DR, which is significantly influenced by inflammation driven retinal vascular degeneration and dysfunction. Ultimately, loss of vision occurs if left untreated. However, the identity of the target cells and their temporal involvement in diabetes-mediated dysfunction need further investigation. Early diabetes-induced stress in photoreceptor cells is proposed as the driver of inflammatory mediated neurovascular changes during diabetes. Although tunicamycin induced ER stress results in photoreceptor loss, its consequences for retinal vascular degeneration and retinal ganglion (RGC) and pigment epithelium (RPE) cell loss remains unclear. Here we show intravitreal delivery of tunicamycin primarily induced ER stress in photoreceptor cells resulting in their loss by apoptosis. This was concomitant with induced expression of the unfolded protein response marker CHOP in these cells. We also demonstrated significant degeneration of retinal capillaries following the loss of photoreceptor cells with minimal impact on loss of RGC and RPE cells. However, activation of retinal microglial and Muller cells were noticeable. Thus, our data support the notion that ER stress mediated dysfunction and/or loss of photoreceptor cells in response to inflammation and oxidative stress could precede retinal vascular and neuronal dysfunction and degeneration.

Unfolded Protein Response (UPR) in Survival, Dormancy, Immunosuppression, Metastasis, and Treatments of Cancer Cells

The endoplasmic reticulum (ER) has diverse functions, and especially misfolded protein modification is in the focus of this review paper. With a highly regulatory mechanism, called unfolded protein response (UPR), it protects cells from the accumulation of misfolded proteins. Nevertheless, not only does UPR modify improper proteins, but it also degrades proteins that are unable to recover. Three pathways of UPR, namely PERK, IRE-1, and ATF6, have a significant role in regulating stress-induced physiological responses in cells. The dysregulated UPR may be involved in diseases, such as atherosclerosis, heart diseases, amyotrophic lateral sclerosis (ALS), and cancer. Here, we discuss the relation between UPR and cancer, considering several aspects including survival, dormancy, immunosuppression, angiogenesis, and metastasis of cancer cells. Although several moderate adversities can subject cancer cells to a hostile environment, UPR can ensure their survival. Excessive unfavorable conditions, such as overloading with misfolded proteins and nutrient deprivation, tend to trigger cancer cell death signaling. Regarding dormancy and immunosuppression, cancer cells can survive chemotherapies and acquire drug resistance through dormancy and immunosuppression. Cancer cells can also regulate the downstream of UPR to modulate angiogenesis and promote metastasis. In the end, regulating UPR through different molecular mechanisms may provide promising anticancer treatment options by suppressing cancer proliferation and progression.

Single-Cell RNA Sequencing of Human Embryonic Stem Cell Differentiation Delineates Adverse Effects of Nicotine on Embryonic Development

Nicotine, the main chemical constituent of tobacco, is highly detrimental to the developing fetus by increasing the risk of gestational complications and organ disorders. The effects of nicotine on human embryonic development and related mechanisms, however, remain poorly understood. Here, we performed single-cell RNA sequencing (scRNA-seq) of human embryonic stem cell (hESC)-derived embryoid body (EB) in the presence or absence of nicotine. Nicotine-induced lineage-specific responses and dysregulated cell-to-cell communication in EBs, shedding light on the adverse effects of nicotine on human embryonic development. In addition, nicotine reduced cell viability, increased reactive oxygen species (ROS), and altered cell cycling in EBs. Abnormal Ca2+ signaling was found in muscle cells upon nicotine exposure, as verified in hESC-derived cardiomyocytes. Consequently, our scRNA-seq data suggest direct adverse effects of nicotine on hESC differentiation at the single-cell level and offer a new method for evaluating drug and environmental toxicity on human embryonic development in utero.

Involvement of Orai1 in tunicamycin-induced endothelial dysfunction

Endoplasmic reticulum (ER) stress is mediated by disturbance of Ca²⁺ homeostasis. The store-operated calcium (SOC) channel is the primary Ca²⁺ channel in non-excitable cells, but its participation in agent-induced ER stress is not clear. In this study, the effects of tunicamycin on Ca²⁺ influx in human umbilical vein endothelial cells (HUVECs) were observed with the fluorescent probe Fluo-4 AM. The effect of tunicamycin on the expression of the unfolded protein response (UPR)-related proteins BiP and CHOP was assayed by western blotting with or without inhibition of Orai1. Tunicamycin induced endothelial dysfunction by activating ER stress. Orai1 expression and the influx of extracellular Ca²⁺ in HUVECs were both upregulated during ER stress. The SOC channel inhibitor SKF96365 reversed tunicamycin-induced endothelial cell dysfunction by inhibiting ER stress. Regulation of tunicamycin-induced ER stress by Orai1 indicates that modification of Orai1 activity may have therapeutic value for conditions with ER stress-induced endothelial dysfunction.

Ticagrelor protects against AngII-induced endothelial dysfunction by alleviating endoplasmic reticulum stress

Ticagrelor has been reported to decrease cardiovascular mortality compared with clopidogrel. This benefit cannot be fully explained by the more efficient platelet inhibition. Many studies demonstrated that ticagrelor improved endothelial function, leaving the mechanism elusive though. The present study aims to investigate whether ticagrelor protects against endothelial dysfunction induced by angiotensinII (AngII) through alleviating endoplasmic reticulum (ER) stress. Male Sprague Dawley rats were infused with AngII or vehicle and administrated with ticagrelor or vehicle for 14 days. Reactive oxygen species (ROS) was detected. Aortas from normal mice were incubated with endoplasmic reticulum stress inducer tunicamycin with or without ticagrelor. Vasorecactivity was measured on wire myography. Rat aortic endothelial cells (RAECs) were pretreated with ticagrelor followed by AngII or tunicamycin. Endothelial nitric oxide synthase (eNOS) phosphorylation and ER stress markers were determined by western blotting. Impaired endothelial function, induction of ER stress, reduced eNOS phosphorylation and elevated ROS generation was restored by ticagrelor treatment in vivo. In addition, tunicamycin induced endothelial dysfunction was improved by ticagrelor. In vitro, the induction of ER stress and inhibited eNOS phosphorylation in REACs exposed to AngII as well as tunicamycin was reversed by co-culturing with ticagrelor. In conclusion, ticagrelor protects against AngII-induced endothelial dysfunction via alleviating ER stress.

Endoplasmic Reticulum Stress, a Driver or an Innocent Bystander in Endothelial Dysfunction Associated with Hypertension?

PURPOSE OF REVIEW

Hypertension (htn) is a polygenic disorder that effects up to one third of the US population. The endoplasmic reticulum (ER) stress response is a homeostatic pathway that regulates membrane structure, protein folding, and secretory function. Emerging evidence suggests that ER stress may induce endothelial dysfunction; however, it is unclear whether ER stress-associated endothelial dysfunction modulates htn.

RECENT FINDINGS

Exogenous and endogenous molecules activate ER stress in the endothelium, and ER stress mediates some forms of neurogenic htn, such as angiotensin II-dependent htn. Human studies suggest that ER stress induces endothelial dysfunction, though direct evidence that ER stress augments blood pressure in humans is lacking. However, animal and cellular models demonstrate direct evidence that ER stress influences htn. ER stress is likely one of many players in a complex interplay among molecular pathways that influence the expression of htn. Targeted activation of specific ER stress pathways may provide novel therapeutic opportunities.

Establishment of pancreatic microenvironment model of ER stress: Quercetin attenuates β-cell apoptosis by invoking nitric oxide-cGMP signaling in endothelial cells

The involvement of endoplasmic reticulum (ER) stress in endothelial dysfunction and diabetes-associated complications has been well documented. Inhibition of ER stress represents a promising therapeutic strategy to attenuate endothelial dysfunction in diabetes. Recent attention has focused on the development of small molecule inhibitors of ER stress to maintain endothelial homeostasis in diabetes. Here we have developed a reliable, robust co-culture system that allows a study on the endothelial cells and pancreatic β-cells crosstalk under ER stress and validated using a known ER stress modulator, quercetin. Furthermore, sensitizing of endothelial cells by quercetin (25 μM) confers protection of pancreatic β-cells against ER stress through nitric oxide (NO^∙) signaling. In addition, increased intracellular insulin and NO^∙-mediated cyclic 3',5'-guanosine monophosphate (cGMP) levels in pancreatic β-cells further confirmed the mechanism of protection under co-culture system. In addition, the potential protein targets of quercetin against ER stress in the endothelial cells were investigated through proteomic profiling and its phosphoprotein targets through Bioplex analysis. On the whole, the developed in vitro co-culture set up can serve as a platform to study the signaling network between the endothelial and pancreatic β-cells as well as provides a mechanistic insight for the validation of novel ER stress modulators.

27-hydroxycholesterol: A novel player in molecular carcinogenesis of breast and prostate cancer

Several studies have suggested an etiological role for hypercholesterolemia in the pathogenesis of breast cancer and prostate cancer (PCa). However, the molecular mechanisms that underlie and mediate the hypercholesterolemia-fostered increased risk for breast cancer and PCa are yet to be determined. The discovery that the most abundant cholesterol oxidized metabolite in the plasma, 27 hydroxycholesterol (27-OHC), is a selective estrogen receptor modulator (SERM) and an agonist of Liver X receptors (LXR) partially fills the void in our understanding and knowledge of the mechanisms that may link hypercholesterolemia to development and progression of breast cancer and PCa. The wide spectrum and repertoire of SERM and LXR-dependent effects of 27-OHC in the context of all facets and aspects of breast cancer and prostate cancer biology are reviewed in this manuscript in a very comprehensive manner. This review highlights recent findings pertaining to the role of 27-OHC in breast cancer and PCa and delineates the signaling mechanisms involved in the governing of different facets of tumor biology, that include tumor cell proliferation, epithelial-mesenchymal transition (EMT), as well as tumor cell invasion, migration, and metastasis. We also discuss the limitations of contemporary studies and lack of our comprehension of the entire gamut of effects exerted by 27-OHC that may be relevant to the pathogenesis of breast cancer and PCa. We unveil and propose potential future directions of research that may further our understanding of the role of 27-OHC in breast cancer and PCa and help design therapeutic interventions against endocrine therapy-resistant breast cancer and PCa.

Endoplasmic reticulum stress and the development of endothelial dysfunction

The vascular endothelium plays a critical role in cardiovascular homeostasis, and thus identifying the underlying causes of endothelial dysfunction has important clinical implications. In this regard, the endoplasmic reticulum (ER) has recently emerged as an important regulator of metabolic processes. Dysfunction within the ER, broadly termed ER stress, evokes the unfolded protein response (UPR), an adaptive pathway that aims to restore ER homeostasis. Although the UPR is the first line of defense against ER stress, chronic activation of the UPR leads to cell dysfunction and death and has recently been implicated in the pathogenesis of endothelial dysfunction. Numerous risk factors for endothelial dysfunction can induce ER stress, which may in turn disrupt endothelial function via direct effects on endothelium-derived vasoactive substances or by activating other pathogenic cellular networks such as inflammation and oxidative stress. This review summarizes the available data linking ER stress to endothelial dysfunction.

Heme oxygenase (HO)-1 induction prevents Endoplasmic Reticulum stress-mediated endothelial cell death and impaired angiogenic capacity

Most of diabetic cardiovascular complications are attributed to endothelial dysfunction and impaired angiogenesis. Endoplasmic Reticulum (ER) and oxidative stresses were shown to play a pivotal role in the development of endothelial dysfunction in diabetes. Hemeoxygenase-1 (HO-1) was shown to protect against oxidative stress in diabetes; however, its role in alleviating ER stress-induced endothelial dysfunction remains not fully elucidated. We aim here to test the protective role of HO-1 against high glucose-mediated ER stress and endothelial dysfunction and understand the underlying mechanisms with special emphasis on oxidative stress, inflammation and cell death. Human Umbilical Vein Endothelial Cells (HUVECs) were grown in either physiological or intermittent high concentrations of glucose for 5days in the presence or absence of Cobalt (III) Protoporphyrin IX chloride (CoPP, HO-1 inducer) or 4-Phenyl Butyric Acid (PBA, ER stress inhibitor). Using an integrated cellular and molecular approach, we then assessed ER stress and inflammatory responses, in addition to apoptosis and angiogenic capacity in these cells. Our results show that HO-1 induction prevented high glucose-mediated increase of mRNA and protein expression of key ER stress markers. Cells incubated with high glucose exhibited high levels of oxidative stress, activation of major inflammatory and apoptotic responses [nuclear factor (NF)-κB and c-Jun N-terminal kinase (JNK)] and increased rate of apoptosis; however, cells pre-treated with CoPP or PBA were fully protected. In addition, high glucose enhanced caspases 3 and 7 cleavage and activity and augmented cleaved poly ADP ribose polymerase (PARP) expression whereas HO-1 induction prevented these effects. Finally, HO-1 induction and ER stress inhibition prevented high glucose-induced reduction in NO release and impaired the angiogenic capacity of HUVECs, and enhanced vascular endothelial growth factor (VEGF)-A expression. Altogether, we show here the critical role of ER stress-mediated cell death in diabetes-induced endothelial dysfunction and impaired angiogenesis and underscore the role of HO-1 induction as a key therapeutic modulator for ER stress response in ischemic disorders and diabetes. Our results also highlight the complex interplay between ER stress response and oxidative stress.

Carriers of a VEGFA enhancer polymorphism selectively binding CHOP/DDIT3 are predisposed to increased circulating levels of thyroid-stimulating hormone

BACKGROUND

Levels of serum thyroid-stimulating hormone (TSH) indicate thyroid function, because thyroid hormone negatively controls TSH release. Genetic variants in the vascular endothelial growth factor A (VEGFA) gene are associated with TSH levels. The aim of this study was to characterise the association of VEGFA variants with TSH in a Danish cohort and to identify and characterise functional variants.

METHODS

We performed an association study of the VEGFA locus for circulating TSH levels in 8445 Danish individuals. Lead variants were tested for allele-specific effects in vitro using luciferase reporter and gel-shift assays.

RESULTS

Four SNPs in VEGFA were associated with circulating TSH (rs9472138, rs881858, rs943080 and rs4711751). For rs881858, the presence of each G-allele was associated with a corresponding decrease in TSH levels of 2.3% (p=8.4×10^-9) and an increase in circulating free T4 levels (p=0.0014). The SNP rs881858 is located in a binding site for CHOP (C/EBP homology protein) and c/EBPβ (ccaat enhancer binding protein β). Reporter-gene analysis showed increased basal enhancer activity of the rs881858 A-allele versus the G-allele (34.5±9.9% (average±SEM), p=0.0012), while co-expression of CHOP effectively suppressed the rs881858 A-allele activity. The A-allele showed stronger binding to CHOP in gel-shift assays.

CONCLUSIONS

VEGF is an important angiogenic signal required for tissue expansion. We show that VEGFA variation giving allele-specific response to transcription factors with overlapping binding sites associate closely with circulating TSH levels. Because CHOP is induced by several types of intracellular stress, this indicates that cellular stress could be involved in the normal or pathophysiological response of the thyroid to TSH.

TRIAL REGISTRATION NUMBER

NCT00289237, NCT00316667; Results.

Posttranscriptional and transcriptional regulation of endothelial nitric-oxide synthase during hypoxia: the role of microRNAs

Understanding the cellular pathways that regulate endothelial nitric oxide (eNOS, NOS3) expression and consequently nitric oxide (NO) bioavailability during hypoxia is a necessary aspect in the development of novel treatments for cardiovascular disorders. eNOS expression and eNOS-dependent NO cellular signaling during hypoxia promote an equilibrium of transcriptional and posttranscriptional molecular mechanisms that belong to both proapoptotic and survival pathways. Furthermore, NO bioavailability results not only from eNOS levels, but also relies on the presence of eNOS substrate and cofactors, the phosphorylation status of eNOS, and the presence of reactive oxygen species (ROS) that can inactivate eNOS. Since both NOS3 levels and these signaling pathways can also be a subject of posttranscriptional modulation by microRNAs (miRNAs), this class of short noncoding RNAs contribute another level of regulation for NO bioavailability. As miRNA antagomirs or specific target protectors could be used in therapeutic approaches to regulate NO levels, either by changing NOS3 mRNA stability or through factors governing eNOS activity, it is critical to understand their role in governing eNOS activity during hypoxa. In contrast to a large number of miRNAs reported to the change eNOS expression during hypoxia, only a few miRNAs modulate eNOS activity. Furthermore, impaired miRNA biogenesis leads to NOS3 mRNA stabilization under hypoxia. Here we discuss the recent studies that define miRNAs’ role in maintaining endothelial NO bioavailability emphasizing those miRNAs that directly modulate NOS3 expression or eNOS activity.

ER Stress and Angiogenesis

Proper tissue vascularization is vital for cellular function as it delivers oxygen, nutrients, hormones, and immune cells and helps to clear cellular debris and metabolic waste products. Tissue angiogenesis occurs to satisfy energy requirements and cellular sensors of metabolic imbalance coordinate vessel growth. In this regard, the classical pathways of the unfolded protein response activated under conditions of ER stress have recently been described to generate angiomodulatory or angiostatic signals. This review elaborates on the link between angiogenesis and ER stress and discusses the implications for diseases characterized by altered vascular homeostasis, such as cancer, retinopathies, and atherosclerosis.

MicroRNA-21 coordinates human multipotent cardiovascular progenitors therapeutic potential

Published clinical trials in patients with ischemic diseases show limited benefit of adult stem cell-based therapy, likely due to their restricted plasticity and commitment toward vascular cell lineage. We aim to uncover the potent regenerative ability of MesP1/stage-specific embryonic antigen 1 (SSEA-1)-expressing cardiovascular progenitors enriched from human embryonic stem cells (hESCs). Injection of only 10(4) hESC-derived SSEA-1(+) /MesP1(+) cells, or their progeny obtained after treatment with VEGF-A or PDGF-BB, was effective enough to enhance postischemic revascularization in immunodeficient mice with critical limb ischemia (CLI). However, the rate of incorporation of hESC-derived SSEA-1(+) /MesP1(+) cells and their derivatives in ischemic tissues was modest. Alternatively, these cells possessed a unique miR-21 signature that inhibited phosphotase and tensin homolog (PTEN) thereby activating HIF-1α and the systemic release of VEGF-A. Targeting miR-21 limited cell survival and inhibited their proangiogenic capacities both in the Matrigel model and in mice with CLI. We next assessed the impact of mR-21 in adult angiogenesis-promoting cells. We observed an impaired postischemic angiogenesis in miR-21-deficient mice. Notably, miR-21 was highly expressed in circulating and infiltrated monocytes where it targeted PTEN/HIF-1α/VEGF-A signaling and cell survival. As a result, miR-21-deficient mice displayed an impaired number of infiltrated monocytes and a defective angiogenic phenotype that could be partially restored by retransplantation of bone marrow-derived cells from wild-type littermates. hESC-derived SSEA-1(+) /MesP1(+) cells progenitor cells are powerful key integrators of therapeutic angiogenesis in ischemic milieu and miR-21 is instrumental in this process as well as in the orchestration of the biological activity of adult angiogenesis-promoting cells.

Endothelial NOS activation induces the blood-brain barrier disruption via ER stress following status epilepticus

The blood-brain barrier (BBB) maintains the unique brain microenvironment, which is separated from the systemic circulating system. Since the endoplasmic reticulum (ER) is an important cell organelle that is responsible for protein synthesis, the correct folding and sorting of proteins contributing to cell survivals, ER stress is a potential cause of cell damage in various diseases. Therefore, it would be worthy to explore the the relationship between the ER stress and BBB disruption during vasogenic edema formation induced by epileptogenic insults. In the present study, we investigated the roles of ER stress in vasogenic edema and its related events in rat epilepsy models provoked by pilocarpine-induced status epilepticus (SE). SE-induced eNOS activation induces BBB breakdown via up-regulation of GRP78 expression and dysfunction of SMI-71 (an endothelial BBB marker) in the piriform cortex (PC). In addition, caveolin-1 peptide (an eNOS inhibitor) effectively attenuated GRP78 expression and down-regulation of SMI-71. Taken together, our findings suggest that eNOS-mediated ER stress may participate in SE-induced vasogenic edema formation. Therefore, the modulation of ER stress may be a considerable strategy for therapy in impairments of endothelial cell function.

The stress-response sensor chop regulates the function and accumulation of myeloid-derived suppressor cells in tumors

Adaptation of malignant cells to the hostile milieu present in tumors is an important determinant of their survival and growth. However, the interaction between tumor-linked stress and antitumor immunity remains poorly characterized. Here, we show the critical role of the cellular stress sensor C/EBP-homologous protein (Chop) in the accumulation and immune inhibitory activity of tumor-infiltrating myeloid-derived suppressor cells (MDSCs). MDSCs lacking Chop had decreased immune-regulatory functions and showed the ability to prime T cell function and induce antitumor responses. Chop expression in MDSCs was induced by tumor-linked reactive oxygen and nitrogen species and regulated by the activating-transcription factor-4. Chop-deficient MDSCs displayed reduced signaling through CCAAT/enhancer-binding protein-β, leading to a decreased production of interleukin-6 (IL-6) and low expression of phospho-STAT3. IL-6 overexpression restored immune-suppressive activity of Chop-deficient MDSCs. These findings suggest the role of Chop in tumor-induced tolerance and the therapeutic potential of targeting Chop in MDSCs for cancer immunotherapy.

Modulation of endothelial cell migration by ER stress and insulin resistance: a role during maternal obesity?

Adverse microenvironmental stimuli can trigger the endoplasmic reticulum (ER) stress pathway, which initiates the unfolded protein response (UPR), to restore protein-folding homeostasis. Several studies show induction of ER stress during obesity. Chronic UPR has been linked to different mechanisms of disease in obese and diabetic individuals, including insulin resistance (IR) and impaired angiogenesis. Endothelial cell (EC) migration is an initial step for angiogenesis, which is associated with remodeling of existing blood vessels. EC migration occurs according to the leader–follower model, involving coordinated processes of chemotaxis, haptotaxis, and mechanotaxis. Thus, a fine-tuning of EC migration is necessary to provide the right timing to form the required vessels during angiogenesis. ER stress modulates EC migration at different levels, usually impairing migration and angiogenesis, although different effects may be observed depending on the tissue and/or microenvironment. In the context of pregnancy, maternal obesity (MO) induces IR in the offspring. Interestingly, several proteins associated with obesity-induced IR are also involved in EC migration, providing a potential link with the ER stress-dependent alterations observed in obese individuals. Different signaling cascades that converge on cytoskeleton regulation directly impact EC migration, including the Akt and/or RhoA pathways. In addition, ER is the main intracellular reservoir for Ca²⁺, which plays a pivotal role during EC migration. Therefore, ER stress-related alterations in Ca²⁺ signaling or Ca²⁺ levels might also produce distorted EC migration. However, the above findings have been studied in the context of adult obesity, and no information has been reported regarding the effect of MO on fetal EC migration. Here we summarize the state of knowledge about the possible mechanisms by which ER stress and IR might impact EC migration and angiogenesis in fetal endothelium exposed to MO during pregnancy.

Diabetes mellitus and ischemic diseases: molecular mechanisms of vascular repair dysfunction

In patients with diabetes mellitus, the ability of ischemic tissue to synchronize the molecular and cellular events leading to restoration of tissue perfusion in response to the atherosclerotic occlusion of a patent artery is markedly impaired. As a consequence, adverse tissue remodeling and the extent of ischemic injury are intensified, leading to increased morbidity and mortality. Growing evidence from preclinical and clinical studies has implicated alterations in hypoxia-inducible factor 1 levels in the abrogation of proangiogenic pathways, including vascular endothelial growth factor A/phosphoinositide 3' kinase/AKT/endothelial nitric oxide synthase and in the activation of antiangiogenic signals characterized by accumulation of advanced glycation end products, reactive oxygen species overproduction, and endoplasmic reticulum stress. In addition, the diabetic milieu shows a switch toward proinflammatory antiregenerative pathways. Finally, the mobilization, subsequent recruitment, and the proangiogenic potential of the different subsets of angiogenesis-promoting bone marrow-derived cells are markedly impaired in the diabetic environment. In this review, we will give an overview of the current understanding on the signaling molecules contributing to the diabetes mellitus-induced impairment of postischemic revascularization mainly in the setting of myocardial infarction or critical limb ischemia.

Mechanism of endoplasmic reticulum stress-induced vascular endothelial dysfunction

BACKGROUND

We recently reported that ER stress plays a key role in vascular endothelial dysfunction during hypertension. In this study we aimed to elucidate the mechanisms by which ER stress induction and oxidative stress impair vascular endothelial function.

METHODOLOGY/PRINCIPAL FINDINGS

We conducted in vitro studies with primary endothelial cells from coronary arteries stimulated with tunicamycin, 1μg/mL, in the presence or absence of two ER stress inhibitors: tauroursodeoxycholic acid (Tudca), 500μg/mL, and 4-phenylbutyric acid (PBA), 5mM. ER stress induction was assessed by enhanced phosphorylation of PERK and eIF2α, and increased expression of CHOP, ATF6 and Grp78/Bip. The ER stress induction increased p38 MAPK phosphorylation, Nox2/4 mRNA levels and NADPH oxidase activity, and decreased eNOS promoter activity, eNOS expression and phosphorylation, and nitrite levels. Interestingly, the inhibition of p38 MAPK pathway reduced CHOP and Bip expressions enhanced by tunicamycin and restored eNOS promoter activation as well as phosphorylation. To study the effects of ER stress induction in vivo, we used C57BL/6J mice and p47phox(-/-) mice injected with tunicamycin or saline. The ER stress induction in mice significantly impaired vascular endothelium-dependent and independent relaxation in C57BL/6J mice compared with p47phox(-/-) mice indicating NADPH oxidase activity as an intermediate for ER stress in vascular endothelial dysfunction.

CONCLUSION/SIGNIFICANCE

We conclude that chemically induced ER stress leads to a downstream enhancement of p38 MAPK and oxidative stress causing vascular endothelial dysfunction. Our results indicate that inhibition of ER stress could be a novel therapeutic strategy to attenuate vascular dysfunction during cardiovascular diseases.

Baicalin protects the cardiomyocytes from ER stress-induced apoptosis: inhibition of CHOP through induction of endothelial nitric oxide synthase

Baicalin, the main active ingredient of the Scutellaria root, exerts anti-oxidant and anti-apoptotic effects in cardiovascular diseases. However, the therapeutic mechanism of baicalin remains unknown. Cultured neonatal rat cardiomyocytes were pre-treated with baicalin (0–50 µM) for 24 h, and subsequently treated with tunicamycin (100 ng/ml). Cell viability was detected by MTT assay, and cell damage was determined by LDH release and TUNEL assay. The expression of CHOP, JNK, caspase-3, eNOS was analyzed by western blot. NO was measured by DAF-FM staining. As a result, treatment with baicalin significantly reduced apoptosis induced by ER stress inducer tunicamycin in cardiomyocytes. Molecularly, baicalin ameliorated tunicamycin-induced ER stress by downregulation of CHOP. In addition, baicalin inverted tunicamycin-induced decreases of eNOS mRNA and protein levels, phospho eNOS and NO production through CHOP pathway. However, the protective effects of baicalin were significantly decreased in cardiomyocytes treated with L-NAME, which suppressed activation of nitric oxide synthase. In conclusion, our results implicate that baicalin could protect cardiomyocytes from ER stress-induced apoptosis via CHOP/eNOS/NO pathway, and suggest the therapeutic values of baicalin against ER stress-associated cardiomyocyte apoptosis.

Postischemic revascularization: from cellular and molecular mechanisms to clinical applications

After the onset of ischemia, cardiac or skeletal muscle undergoes a continuum of molecular, cellular, and extracellular responses that determine the function and the remodeling of the ischemic tissue. Hypoxia-related pathways, immunoinflammatory balance, circulating or local vascular progenitor cells, as well as changes in hemodynamical forces within vascular wall trigger all the processes regulating vascular homeostasis, including vasculogenesis, angiogenesis, arteriogenesis, and collateral growth, which act in concert to establish a functional vascular network in ischemic zones. In patients with ischemic diseases, most of the cellular (mainly those involving bone marrow-derived cells and local stem/progenitor cells) and molecular mechanisms involved in the activation of vessel growth and vascular remodeling are markedly impaired by the deleterious microenvironment characterized by fibrosis, inflammation, hypoperfusion, and inhibition of endogenous angiogenic and regenerative programs. Furthermore, cardiovascular risk factors, including diabetes, hypercholesterolemia, hypertension, diabetes, and aging, constitute a deleterious macroenvironment that participates to the abrogation of postischemic revascularization and tissue regeneration observed in these patient populations. Thus stimulation of vessel growth and/or remodeling has emerged as a new therapeutic option in patients with ischemic diseases. Many strategies of therapeutic revascularization, based on the administration of growth factors or stem/progenitor cells from diverse sources, have been proposed and are currently tested in patients with peripheral arterial disease or cardiac diseases. This review provides an overview from our current knowledge regarding molecular and cellular mechanisms involved in postischemic revascularization, as well as advances in the clinical application of such strategies of therapeutic revascularization.

Pro-angiogenic cell-based therapy for the treatment of ischemic cardiovascular diseases

Pro-angiogenic cell therapy has emerged as a promising option to treat patients with acute myocardial infarction or with critical limb ischemia. Exciting pre-clinical studies have prompted the initiation of numerous clinical trials based on administration of stem/progenitor cells with pro-angiogenic potential. Most of the clinical studies performed so far have used bone marrow-derived or peripheral blood-derived mononuclear cells and showed, overall, a modest but significant benefit on tissue remodeling and function in patients with ischemic diseases. These mixed results pave the way for the development of strategies to overcome the limitation of autologous cell therapy and to propose more efficient approaches. Such strategies include pretreatment of cells with activators to augment cell recruitment and survival in the ischemic target area and/or the improvement of cell functions such as their paracrine ability to release proangiogenic factors and vasoactive molecules. In addition, efforts should be directed towards stimulation of both angiogenesis and vessel maturation, the development of a composite product consisting of stem/progenitor cells encapsulated in a biomaterial and the use of additional sources of regenerative cells.

Vascular endothelial cell growth-activated XBP1 splicing in endothelial cells is crucial for angiogenesis

BACKGROUND

Vascular endothelial cell growth factor plays a pivotal role in angiogenesis via regulating endothelial cell proliferation. The X-box binding protein 1 (XBP1) is believed to be a signal transducer in the endoplasmic reticulum stress response. It is unknown whether there is crosstalk between vascular endothelial cell growth factor signaling and XBP1 pathway.

METHODS AND RESULTS

We found that vascular endothelial cell growth factor induced the kinase insert domain receptor internalization and interaction through C-terminal domain with the unspliced XBP1 and the inositol requiring enzyme 1 α in the endoplasmic reticulum, leading to inositol requiring enzyme 1 α phosphorylation and XBP1 mRNA splicing, which was abolished by siRNA-mediated knockdown of kinase insert domain receptor. Spliced XBP1 regulated endothelial cell proliferation in a PI3K/Akt/GSK3β/β-catenin/E2F2-dependent manner and modulated the cell size increase in a PI3K/Akt/GSK3β/β-catenin/E2F2-independent manner. Knockdown of XBP1 or inositol requiring enzyme 1 α decreased endothelial cell proliferation via suppression of Akt/GSK3β phosphorylation, β-catenin nuclear translocation, and E2F2 expression. Endothelial cell-specific knockout of XBP1 (XBP1ecko) in mice retarded the retinal vasculogenesis in the first 2 postnatal weeks and impaired the angiogenesis triggered by ischemia. Reconstitution of XBP1 by Ad-XBP1s gene transfer significantly improved angiogenesis in ischemic tissue in XBP1ecko mice. Transplantation of bone marrow from wild-type o XBP1ecko mice could also slightly improve the foot blood reperfusion in ischemic XBP1ecko mice.

CONCLUSIONS

These results suggest that XBP1 can function via growth factor signaling pathways to regulate endothelial proliferation and angiogenesis.

Ubiquitous transcription factor YY1 promotes zebrafish liver steatosis and lipotoxicity by inhibiting CHOP-10 expression

The ubiquitous transcription factor Yin Yang 1 (YY1) is known to have diverse and complex cellular functions. Although relevant literature has reported that YY1 expression can induce the down-regulation of C/EBP homologous protein 10 (CHOP-10) and then allow the transactivation of certain transcription factors required for lipogenesis, similar properties of YY1 are poorly understood in animal model systems. In this study, we demonstrate hepatic lipid accumulation in YY1 transgenic zebrafish (GY). Oil-red staining cells were predominantly increased in the livers of both GY larvae and adults, indicating that YY1 functionally promoted lipid accumulation in GY livers. Molecular analysis revealed that YY1 over-expression contributed to the accumulation of hepatic triglycerides (TGs) by inhibiting CHOP-10 expression in the juvenile GY and 3 other fish cell lines; the decreased CHOP-10 expression then induced the transactivation of C/EBP-α and PPAR-γ expression. CHOP-10 morpholino (MO)-injected and rosiglitazone-treated G-liver larvae showed liver steatosis by transactivating PPAR-γ. PPAR-γ MO-injected, and GW9662- and astaxanthin-treated GY larvae showed no liver steatosis by inhibiting PPAR-γ. Moreover, a fatty acid (FA) accumulation and a TG decrease were found in the liver of aged GY, leading to the induction of FA-oxidizing systems that increased hepatic oxidative stress and liver damage. This study is the first to examine YY1 as a potential stimulator for GY liver steatosis and lipotoxicity.

VennPlex--a novel Venn diagram program for comparing and visualizing datasets with differentially regulated datapoints

With the development of increasingly large and complex genomic and proteomic data sets, an enhancement in the complexity of available Venn diagram analytical programs is becoming increasingly important. Current freely available Venn diagram programs often fail to represent extra complexity among datasets, such as regulation pattern differences between different groups. Here we describe the development of VennPlex, a program that illustrates the often diverse numerical interactions among multiple, high-complexity datasets, using up to four data sets. VennPlex includes versatile output features, where grouped data points in specific regions can be easily exported into a spreadsheet. This program is able to facilitate the analysis of two to four gene sets and their corresponding expression values in a user-friendly manner. To demonstrate its unique experimental utility we applied VennPlex to a complex paradigm, i.e. a comparison of the effect of multiple oxygen tension environments (1–20% ambient oxygen) upon gene transcription of primary rat astrocytes. VennPlex accurately dissects complex data sets reliably into easily identifiable groups for straightforward analysis and data output. This program, which is an improvement over currently available Venn diagram programs, is able to rapidly extract important datasets that represent the variety of expression patterns available within the data sets, showing potential applications in fields like genomics, proteomics, and bioinformatics.