Endoplasmic reticulum stress: its role in disease and novel prospects for therapy

Cross-Talk Between FSH and Endoplasmic Reticulum Stress: A Mutually Suppressive Relationship

Suboptimal cellular conditions result in the accumulation of unfolded proteins in the endoplasmic reticulum (ER) and trigger ER stress. In this study, we investigated the effects of follicle stimulating hormone (FSH) on ER stress in granulosa cells (GCs) obtained from 3-week-old female C57BL6 mice 24 or 48 hours after intraperitoneal injection of 5 IU pregnant mare's serum gonadotropin (PMSG), and in primary mouse GCs in culture treated with FSH (10-100 mIU/mL) for 24 or 48 hours. Moreover, mouse GCs in culture were treated with tunicamycin (Tm) or thapsigargin (Tp), which induce ER stress by inhibiting N-glycosylation of ER proteins and ER calcium adenosine triphosphatase, respectively, and their response to FSH was evaluated. We found that FSH attenuated ER stress in mouse GCs in vivo and in vitro; messenger RNA levels of ER stress-associated genes Xbp1s, Atf6, Chop, and Casp12 were decreased upon exposure to FSH/PMSG. Activating transcription factor 4 protein levels also demonstrated consistent decrease following FSH stimulation. Both Tm and Tp treatments inhibited FSH response, ER stress-induced cells did not show any change in estradiol levels in response to FSH, whereas in untreated GCs, estradiol production increased 3-fold after incubation with FSH for 60 hours. Furthermore, ER stress-induced cells failed to demonstrate aromatase (Cyp19a1) expression upon exposure to FSH. Importantly, under high-ER stress conditions FSH stimulation was unable to downregulate the expression of ER stress-associated genes. Our findings suggest that FSH decreases ER stress in GCs under physiologic conditions. However, under conditions that cause a significant increase in ER stress, FSH response is attenuated.

4-Phenylbutyric Acid (4-PBA) and Lithium Cooperatively Attenuate Cell Death during Oxygen-Glucose Deprivation (OGD) and Reoxygenation

Hypoxia is an important cause of brain injury in ischemic stroke. It is known that endoplasmic reticulum (ER) stress is an important determinant of cell survival or death during hypoxia. However, the signaling pathways and molecular mechanisms involved remain to be studied in more detail. To investigate whether inhibition of ER stress promotes neuroprotection pathways, we applied an in vitro oxygen-glucose deprivation (OGD) followed by reoxygenation model of human SK-N-MC neuronal cell cultures in this study. Our results showed that neuronal cell death was induced in this model during the OGD reoxygenation by the sustained ER stress, but not during OGD phase. However, treatment of the cultures with lithium with the OGD reoxygenation insult did not result in neuroprotection, whereas concomitant treatment of chemical chaperon 4-phenylbutyric acid (4-PBA) provides protective effects in ER stress-exposed cells. Moreover, 4-PBA rescued ER stress-suppressed Akt protein biosynthesis, which works cooperatively with lithium in the activation of Akt downstream signaling by inhibition of autophagy-induced cell death. Taken together, our finding provides a possible mechanism by which 4-PBA and lithium contribute to mediate neuroprotection cooperatively. This result may potentially be a useful therapeutic strategy for ischemic stroke.

Altered activation of protein kinase PKR and enhanced apoptosis in dystonia cells carrying a mutation in PKR activator protein PACT

PACT is a stress-modulated activator of the interferon-induced double-stranded RNA-activated protein kinase (PKR). Stress-induced phosphorylation of PACT is essential for PACT's association with PKR leading to PKR activation. PKR activation leads to phosphorylation of translation initiation factor eIF2α inhibition of protein synthesis and apoptosis. A recessively inherited form of early-onset dystonia DYT16 has been recently identified to arise due to a homozygous missense mutation P222L in PACT. To examine if the mutant P222L protein alters the stress-response pathway, we examined the ability of mutant P222L to interact with and activate PKR. Our results indicate that the substitution mutant P222L activates PKR more robustly and for longer duration albeit with slower kinetics in response to the endoplasmic reticulum stress. In addition, the affinity of PACT-PACT and PACT-PKR interactions is enhanced in dystonia patient lymphoblasts, thereby leading to intensified PKR activation and enhanced cellular death. P222L mutation also changes the affinity of PACT-TRBP interaction after cellular stress, thereby offering a mechanism for the delayed PKR activation in response to stress. Our results demonstrate the impact of a dystonia-causing substitution mutation on stress-induced cellular apoptosis.

GRP78 expression beyond cellular stress: A biomarker for tumor manipulation

Physiological stress takes place in the endoplasmic reticulum (ER) of cells where activation and up-regulation of genes and proteins are primarily induced to enhance pro-survival mechanisms such as the unfolded protein response (UPR). A dominant protein in the UPR response is the heat shock GRP78 protein. Although GRP78 is primarily located in the ER, under certain conditions it is transported to the cell surface, where it acts as a receptor inducing pathways of cell signaling such as proliferation or apoptosis. In the prolonged chronic stress transportation of the GRP78 from the ER to the cell membrane is a major event where in addition to the presentation of the GRP78 as a receptor to various ligands, it also marks the cells that will proceed to apoptotic pathways. In the normal cell that under stress acquires cell surface GRP78 and in the tumor cell that already presents cell surface GRP78, cell surface GRP78 is an apoptotic flag. The internalization of GRP78 from the cell surface in normal cells by ligands such as peptides will enhance cell survival and alleviate cardiovascular ischemic diseases. The absence of cell surface GRP78 in the tumor cells portends proliferative and metastatic tumors. Pharmacological induction of cell surface GRP78 will induce the process of apoptosis and might be used as a therapeutic modality for cancer treatment.

The Orphan Nuclear Receptor NR4A1 Protects Pancreatic β-Cells from Endoplasmic Reticulum (ER) Stress-mediated Apoptosis

The role of NR4A1 in apoptosis is controversial. Pancreatic β-cells often face endoplasmic reticulum (ER) stress under adverse conditions such as high free fatty acid (FFA) concentrations and sustained hyperglycemia. Severe ER stress results in β-cell apoptosis. The aim of this study was to analyze the role of NR4A1 in ER stress-mediated β-cell apoptosis and to characterize the related mechanisms. We confirmed that upon treatment with the ER stress inducers thapsigargin (TG) or palmitic acid (PA), the mRNA and protein levels of NR4A1 rapidly increased in both MIN6 cells and mouse islets. NR4A1 overexpression in MIN6 cells conferred resistance to cell loss induced by TG or PA, as assessed by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, and TUNEL assays indicated that NR4A1 overexpression also protected against ER stress-induced apoptosis. This conclusion was further confirmed by experiments exploiting siRNA to knockdown NR4A1 expression in MIN6 cells or exploiting NR4A1 knock-out mice. NR4A1 overexpression in MIN6 cells reduced C/EBP homologous protein (CHOP) expression and Caspase3 activation induced by TG or PA. NR4A1 overexpression in MIN6 cells or mouse islets resulted in Survivin up-regulation. A critical regulatory element was identified in Survivin promoter (-1872 bp to -1866 bp) with a putative NR4A1 binding site; ChIP assays demonstrated that NR4A1 physically associates with the Survivin promoter. In conclusion, NR4A1 protects pancreatic β-cells against ER stress-mediated apoptosis by up-regulating Survivin expression and down-regulating CHOP expression, which we termed as "positive and negative regulation."

Lack of GCN5 remarkably enhances the resistance against prolonged endoplasmic reticulum stress-induced apoptosis through up-regulation of Bcl-2 gene expression

The endoplasmic reticulum (ER), a complex membrane structure, has important roles in all eukaryotic cells. Catastrophe of its functions would lead to ER stress that causes various diseases such as cancer, neurodegenerative diseases, diabetes and so on. Prolonged ER stress could trigger apoptosis via activation of various signal transduction pathways. To investigate physiological roles of histone acetyltransferase GCN5 in regulation of ER stress, we analyzed responses of homozygous GCN5-deficient DT40 mutants, ΔGCN5, against ER stress. GCN5-deficiency in DT40 caused drastic resistance against apoptosis induced by pharmacological ER stress agents (thapsigargin and tunicamycin). Pharmaceutical analysis using specific Bcl-2 inhibitors showed that the drastic resistance against prolonged ER stress-induced apoptosis is, in part, due to up-regulation of Bcl-2 gene expression in ΔGCN5. These data revealed that GCN5 is involved in regulation of prolonged ER stress-induced apoptosis through controlling Bcl-2 gene expression.

HIV Protease Inhibitors Sensitize Human Head and Neck Squamous Carcinoma Cells to Radiation by Activating Endoplasmic Reticulum Stress

Background

Human head and neck squamous cell carcinoma (HNSCC) is the sixth most malignant cancer worldwide. Despite significant advances in the delivery of treatment and surgical reconstruction, there is no significant improvement of mortality rates for this disease in the past decades. Radiotherapy is the core component of the clinical combinational therapies for HNSCC. However, the tumor cells have a tendency to develop radiation resistance, which is a major barrier to effective treatment. HIV protease inhibitors (HIV PIs) have been reported with radiosensitizing activities in HNSCC cells, but the underlying cellular/molecular mechanisms remain unclear. Our previous study has shown that HIV PIs induce cell apoptosis via activation of endoplasmic reticulum (ER) stress. The aim of this study was to examine the role of ER stress in HIV PI-induced radiosensitivity in human HNSCC.

Methodology and Principal Findings

HNSCC cell lines, SQ20B and FaDu, and the most commonly used HIV PIs, lopinavir and ritonavir (L/R), were used in this study. Clonogenic assay was used to assess the radiosensitivity. Cell viability, apoptosis and cell cycle were analyzed using Cellometer Vision CBA. The mRNA and protein levels of ER stress-related genes (eIF2α, CHOP, ATF-4, and XBP-1), as well as cell cycle related protein, cyclin D1, were detected by real time RT-PCR and Western blot analysis, respectively. The results demonstrated that L/R dose-dependently sensitized HNSCC cells to irradiation and inhibited cell growth. L/R-induced activation of ER stress was correlated to down-regulation of cyclin D1 expression and cell cycle arrest under G0/G1 phase.

Conclusion and Significance

HIV PIs sensitize HNSCC cells to radiotherapy by activation of ER stress and induction of cell cycle arrest. Our results provided evidence that HIV PIs can be potentially used in combination with radiation in the treatment of HNSCC.

ER proteostasis addiction in cancer biology: Novel concepts

Endoplasmic reticulum (ER) stress is generated by various physiological and pathological conditions that induce an accumulation of misfolded proteins in its lumen. ER stress activates the unfolded protein response (UPR), an adaptive reaction to cope with protein misfolding to and restore proteostasis. However, chronic ER stress results in apoptosis. In solid tumors, the UPR mediates adaptation to various environmental stressors, including hypoxia, low in pH and low nutrients availability, driving positive selection. Recent findings support the concept that UPR signaling also contributes to other relevant cancer-related event that may not be related to ER stress, including angiogenesis, genomic instability, metastasis and immunomodulation. In this article, we overview novel discoveries highlighting the impact of the UPR to different aspects of cancer biology beyond its known role as a survival factor to the hypoxic environment observed in solid tumors.

Pachymic acid inhibits growth and induces apoptosis of pancreatic cancer in vitro and in vivo by targeting ER stress

Pachymic acid (PA) is a purified triterpene extracted from medicinal fungus Poria cocos. In this paper, we investigated the anticancer effect of PA on human chemotherapy resistant pancreatic cancer. PA triggered apoptosis in gemcitabine-resistant pancreatic cancer cells PANC-1 and MIA PaCa-2. Comparative gene expression array analysis demonstrated that endoplasmic reticulum (ER) stress was induced by PA through activation of heat shock response and unfolded protein response related genes. Induced ER stress was confirmed by increasing expression of XBP-1s, ATF4, Hsp70, CHOP and phospho-eIF2α. Moreover, ER stress inhibitor tauroursodeoxycholic acid (TUDCA) blocked PA induced apoptosis. In addition, 25 mg kg-1 of PA significantly suppressed MIA PaCa-2 tumor growth in vivo without toxicity, which correlated with induction of apoptosis and expression of ER stress related proteins in tumor tissues. Taken together, growth inhibition and induction of apoptosis by PA in gemcitabine-resistant pancreatic cancer cells were associated with ER stress activation both in vitro and in vivo. PA may be potentially exploited for the use in treatment of chemotherapy resistant pancreatic cancer.

Endoplasmic reticulum quality control in cancer: Friend or foe

Quality control systems in the endoplasmic reticulum (ER) mediated by unfolded protein response (UPR) and endoplasmic reticulum associated degradation (ERAD) ensure cellular function and organismal survival. Recent studies have suggested that ER quality-control systems in cancer cells may serve as a double-edged sword that aids progression as well as prevention of tumor growth in a context-dependent manner. Here we review recent advances in our understanding of the complex relationship between ER proteostasis and cancer pathology, with a focus on the two most conserved ER quality-control mechanisms--the IRE1α-XBP1 pathway of the UPR and SEL1L-HRD1 complex of the ERAD.

Apoptosis induction associated with the ER stress response through up-regulation of JNK in HeLa cells by gambogic acid

Background

Gambogic acid (GA) was extracted from the dried yellow resin of gamboge (Garcinia hanburyi) which is traditionally used as a coloring material for painting and cloth dying. Gamboge has been also used as a folk medicine for an internal purgative and externally infected wound. We focused on the mechanisms of apoptosis induction by GA through the unfold protein response (ER stress) in HeLa cells.

Methods

The cytotoxic effect of GA against HeLa cells was determined by trypan blue exclusion assay. Markers of ER stress such as XBP-1, GRP78, CHOP, GADD34 and ERdj4 were analyzed by RT-PCR and Real-time RT-PCR. Cell morphological changes and apoptotic proteins were performed by Hoechst33342 staining and Western blotting technique.

Results

Our results indicated a time- and dose-dependent decrease of cell viability by GA. The ER stress induction is determined by the up-regulation of spliced XBP1 mRNA and activated GRP78, CHOP, GADD34 and ERdj4 expression. GA also induced cell morphological changes such as nuclear condensation, membrane blebbing and apoptotic body in Hela cells. Apoptosis cell death detected by increased DR5, caspase-8, −9, and −3 expression as well as increased cleaved-PARP, while decreased Bcl-2 upon GA treatment. In addition, phosphorylated JNK was up-regulated but phosphorylated ERK was down-regulated after exposure to GA.

Conclusions

These results suggest that GA induce apoptosis associated with the ER stress response through up-regulation of p-JNK and down-regulation of p-ERK in HeLa cells.

Nelfinavir and other protease inhibitors in cancer: mechanisms involved in anticancer activity

OBJECTIVE

To review the mechanisms of anti-cancer activity of nelfinavir and other protease inhibitors (PIs) based on evidences reported in the published literature.

METHODS

We extensively reviewed the literature concerning nelfinavir (NFV) as an off target anti-cancer drug and other PIs. A classification of PIs based on anti-cancer mode of action was proposed. Controversies regarding nelfinavir mode of action were also addressed.

CONCLUSIONS

The two main mechanisms involved in anti-cancer activity are endoplasmic reticulum stress-unfolded protein response pathway and Akt inhibition. However there are many other effects, partially dependent and independent of those mentioned, that may be useful in cancer treatment, including MMP-9 and MMP-2 inhibition, down-regulation of CDK-2, VEGF, bFGF, NF-kB, STAT-3, HIF-1 alfa, IGF, EGFR, survivin, BCRP, androgen receptor, proteasome, fatty acid synthase (FAS), decrease in cellular ATP concentration and upregulation of TRAIL receptor DR5, Bax, increased radiosensitivity, and autophagy. The end result of all these effects is slower growth, decreased angiogenesis, decreased invasion and increased apoptosis, which means reduced proliferation and increased cancer cells death. PIs may be classified according to their anticancer activity at clinically achievable doses, in AKT inhibitors, ER stressors and Akt inhibitors/ER stressors. Beyond the phase I trials that have been recently completed, adequately powered and well-designed clinical trials are needed in the various cancer type settings, and specific trials where NFV is tested in association with other known anti-cancer pharmaceuticals should be sought, in order to find an appropriate place for NFV in cancer treatment. The analysis of controversies on the molecular mechanisms of NFV hints to the possibility that NFV works in a different way in tumor cells and in hepatocytes and adipocytes.

Gating behavior of endoplasmic reticulum potassium channels of rat hepatocytes in diabetes

BACKGROUND

Defects in endoplasmic reticulum homeostasis are common occurrences in different diseases, such as diabetes, in which the function of endoplasmic reticulum is disrupted. It is now well established that ion channels of endoplasmic reticulum membrane have a critical role in endoplasmic reticulum luminal homeostasis. Our previous studies showed the presence of an ATP-sensitive cationic channel in endoplasmic reticulum. Therefore, in this study, we examined and compared the activities of this channel in control and diabetic rats using single-channel recording techniques.

METHOD

Male Wistar rats were made diabetic for 2 weeks with a single dose injection of streptozotocin (45 mg/kg). Ion channel incorporation of rough endoplasmic reticulum of diabetic hepatocytes into the bilayer lipid membrane allowed the characterization of K+ channel.

RESULTS

Ion channel incorporation of rough endoplasmic reticulum vesicles into the bilayer lipid revealed that the channel current-voltage (I-V) relation with a mean slope conductance of 520 ± 19 pS was unaffected in diabetes. Interestingly, the channel Po-voltage relation was significantly lower in diabetic rats at voltages above +30 mV.

CONCLUSION

We concluded that the endoplasmic reticulum cationic channel is involved in diabetes. Also, this finding could be considered as a goal for further therapeutic plans.

Loss of ion transporters and increased unfolded protein response in Fuchs' dystrophy

PURPOSE

Fuchs' endothelial corneal dystrophy (FECD), which affects approximately 5% of the population over 40 in the U.S.A., is a major cause of corneal transplantation. FECD is associated with mutations of a variety of unrelated genes: SLC4A11, COL8A2, TCF8, and LOXHD1. The current pathological description of the dystrophy includes deficiency of corneal endothelium (CE) pump function and induction of the unfolded protein response (UPR). This study aims to determine the contribution of the two mechanisms by assessing the expression levels of (1) seven endothelial ion transporters known to regulate stromal hydration and (2) UPR related genes in a set of six CE samples obtained from FECD patients compared to that of normal controls.

METHODS

CE samples collected during FECD keratoplasty or from an eye bank (normal control) were transferred into an RNA stabilizing agent and refrigerated. Total RNA from each CE specimen was individually extracted. The expression levels of ion transporters and UPR genes were tested using quantitative real-time (RT) PCR and a UPR specific PCR array, respectively.

RESULTS

In normal CE, the comparative expression levels of ion transporters in decreasing order were SLC4A11, Na(+)/K(+) ATPase, pNBCe1, and NHE1, followed by the isoforms of monocarboxylate transporters (MCTs). In FECD samples, Na(+)/K(+) ATPase and MCTs 1 and 4 were significantly downregulated compared to normal controls (p<0.05). The PCR array tested 84 UPR related genes. Data analysis showed upregulation of 39 genes and downregulation of three genes, i.e., approximately 51% of the tested genes had their expression altered in FECD samples with a difference greater than ± twofold regulation. Thirteen of the altered genes showed significant changes (p<0.05). The PCR array results were validated by quantitative RT-PCR.

CONCLUSIONS

FECD samples had evident UPR with significant changes in the expression of the protein processing pathway genes. The significant downregulation of ion transporters indicates simultaneous compromised CE pump function in Fuchs' dystrophy.

Pharmacological induction of cell surface GRP78 contributes to apoptosis in triple negative breast cancer cells

Breast cancer tumor with triple-negative receptors (estrogen, progesterone and Her 2, receptors) is the most aggressive and deadly subtype, with high rates of disease recurrence and poor survival. Here, we show that induction in cell surface GRP78 by doxorubicin and tunicamycin was associated with CHOP/GADD153 upregulation and increase in apoptosis in triple negative breast cancer tumor cells. GRP78 is a major regulator of the stress induced unfolded protein response pathway and CHOP/GADD153 is a pro-apoptotic transcription factor associated exclusively with stress induced apoptosis. The blocking of cell surface GRP78 by anti-GRP78 antibody prevented apoptosis, suggesting that induction of cell surface GRP78 by doxorubicin and tunicamycin is required for apoptosis. A better understanding of stress induction of apoptotic signaling in triple negative breast cancer cells may help to define new therapeutic strategies.

Size-dependent accumulation of particles in lysosomes modulates dendritic cell function through impaired antigen degradation

Introduction

Nanosized particles may enable therapeutic modulation of immune responses by targeting dendritic cell (DC) networks in accessible organs such as the lung. To date, however, the effects of nanoparticles on DC function and downstream immune responses remain poorly understood.

Methods

Bone marrow–derived DCs (BMDCs) were exposed in vitro to 20 or 1,000 nm polystyrene (PS) particles. Particle uptake kinetics, cell surface marker expression, soluble protein antigen uptake and degradation, as well as in vitro CD4⁺ T-cell proliferation and cytokine production were analyzed by flow cytometry. In addition, co-localization of particles within the lysosomal compartment, lysosomal permeability, and endoplasmic reticulum stress were analyzed.

Results

The frequency of PS particle–positive CD11c⁺/CD11b⁺ BMDCs reached an early plateau after 20 minutes and was significantly higher for 20 nm than for 1,000 nm PS particles at all time-points analyzed. PS particles did not alter cell viability or modify expression of the surface markers CD11b, CD11c, MHC class II, CD40, and CD86. Although particle exposure did not modulate antigen uptake, 20 nm PS particles decreased the capacity of BMDCs to degrade soluble antigen, without affecting their ability to induce antigen-specific CD4⁺ T-cell proliferation. Co-localization studies between PS particles and lysosomes using laser scanning confocal microscopy detected a significantly higher frequency of co-localized 20 nm particles as compared with their 1,000 nm counterparts. Neither size of PS particle caused lysosomal leakage, expression of endoplasmic reticulum stress gene markers, or changes in cytokines profiles.

Conclusion

These data indicate that although supposedly inert PS nanoparticles did not induce DC activation or alteration in CD4⁺ T-cell stimulating capacity, 20 nm (but not 1,000 nm) PS particles may reduce antigen degradation through interference in the lysosomal compartment. These findings emphasize the importance of performing in-depth analysis of DC function when developing novel approaches for immune modulation with nanoparticles.

Antitumor effects of a sirtuin inhibitor, tenovin-6, against gastric cancer cells via death receptor 5 up-regulation

Up-regulated sirtuin 1 (SIRT1), an NAD⁺-dependent class III histone deacetylase, deacetylates p53 and inhibits its transcriptional activity, leading to cell survival. SIRT1 overexpression has been reported to predict poor survival in some malignancies, including gastric cancer. However, the antitumor effect of SIRT1 inhibition remains elusive in gastric cancer. Here, we investigated the antitumor mechanisms of a sirtuin inhibitor, tenovin-6, in seven human gastric cancer cell lines (four cell lines with wild-type TP53, two with mutant-type TP53, and one with null TP53). Interestingly, tenovin-6 induced apoptosis in all cell lines, not only those with wild-type TP53, but also mutant-type and null versions, accompanied by up-regulation of death receptor 5 (DR5). In the KatoIII cell line (TP53-null), DR5 silencing markedly attenuated tenovin-6-induced apoptosis, suggesting that the pivotal mechanism behind its antitumor effects is based on activation of the death receptor signal pathway. Although endoplasmic reticulum stress caused by sirtuin inhibitors was reported to induce DR5 up-regulation in other cancer cell lines, we could not find marked activation of its related molecules, such as ATF6, PERK, and CHOP, in gastric cancer cells treated with tenovin-6. Tenovin-6 in combination with docetaxel or SN-38 exerted a slight to moderate synergistic cytotoxicity against gastric cancer cells. In conclusion, tenovin-6 has potent antitumor activity against human gastric cancer cells via DR5 up-regulation. Our results should be helpful for the future clinical development of sirtuin inhibitors.

Defining differences among perivascular cells derived from human pluripotent stem cells

Distinguishing between perivascular cell types remains a hurdle in vascular biology due to overlapping marker expressions and similar functionalities. Clarifying and defining heterogeneities in vitro among perivascular cells could lead to improved cell-based tissue regeneration strategies and a better understanding of human developmental processes. We studied contractile vascular smooth muscle cells (vSMCs), synthetic vSMCs, and pericytes derived from a common human pluripotent stem cell source. Using in vitro cultures, we show unique cell morphology, subcellular organelle organization (namely endoplasmic reticulum, mitochondria, and stress fibers), and expression of smooth muscle myosin heavy chain and elastin for each cell type. While differences in extracellular matrix deposition and remodeling were less pronounced, the multipotency, in vivo, migratory, invasion, and contractile functionalities are distinctive for each cell type. Overall, we define a repertoire of functional phenotypes in vitro specific for each of the human perivascular cell types, enabling their study and use in basic and translational research.

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Contractile and synthetic vSMCs and pericytes were derived from a common hiPSC line

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Morphology and organelle organization differ among the perivascular derivatives

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SMMHC and elastin specify the mature contractile vSMC phenotype

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Migration, invasion, and contractility are unique for each perivascular cell type.

Phenotypic comparison of common mouse strains developing high-fat diet-induced hepatosteatosis

Genetic predisposition and environmental factors contribute to an individual's susceptibility to develop hepatosteatosis. In a systematic, comparative survey we focused on genotype-dependent and -independent adaptations early in the pathogenesis of hepatosteatosis by characterizing C3HeB/FeJ, C57BL/6NTac, C57BL/6J, and 129P2/OlaHsd mice after 7, 14, or 21 days high-fat-diet exposure. Strain-specific metabolic responses during diet challenge and liver transcript signatures in mild hepatosteatosis outline the suitability of particular strains for investigating the relationship between hepatocellular lipid content and inflammation, glucose homeostasis, insulin action, or organelle physiology. Genetic background-independent transcriptional adaptations in liver paralleling hepatosteatosis suggest an early increase in the organ's vulnerability to oxidative stress damage what could advance hepatosteatosis to steatohepatitis. "Universal" adaptations in transcript signatures and transcription factor regulation in liver link insulin resistance, type 2 diabetes mellitus, cancer, and thyroid hormone metabolism with hepatosteatosis, hence, facilitating the search for novel molecular mechanisms potentially implicated in the pathogenesis of human non-alcoholic-fatty-liver-disease.