UPR

Mutations in rhodopsin, the light sensitive protein of rod cells, are the most common cause of dominant retinitis pigmentosa (RP), a type of inherited blindness caused by the dysfunction and death of photoreceptor cells. The P23H mutation, the most frequent single cause of RP in the USA, causes rhodopsin misfolding and induction of the unfolded protein response (UPR), an adaptive ER stress response and signalling network that aims to enhance the folding and degradation of misfolded proteins to restore proteostasis...

Due to environmental insult or innate genetic deficiency, protein folding environments of the mitochondrial matrix are prone to dysregulation, prompting the activation of a specific organellar stress-response mechanism the mitochondrial unfolded protein response (UPR(MT)). In Caenorhabditis elegans, mitochondrial damage leads to nuclear translocation of the ATFS-1 transcription factor to activate the UPR(MT) After short-term acute stress has been mitigated, the UPR(MT) is eventually suppressed to restore homeostasis to C...

Cardiac myocytes are the cells responsible for the robust ability of the heart to pump blood throughout the circulatory system. Cardiac myocytes grow in response to a variety of physiological and pathological conditions; this growth challenges endoplasmic reticulum-protein quality control (ER-PQC), a major feature of which includes the unfolded protein response (UPR). ER-PQC and the UPR in cardiac myocytes growing under physiological conditions, including normal development, exercise, and pregnancy, are sufficient to support hypertrophic growth of each cardiac myocyte...

Cell migration inducing hyaluronan binding protein (CEMIP) has been suggested as a contributor in the carcinogenesis of colorectal cancer (CRC). Cancer cells can adapt to endoplasmic reticulum (ER) stress by initiating unfolded protein response (UPR). This study aimed at investigating whether CEMIP affected the UPR of CRC cells, with a focus on 78 kDa glucose-regulated protein (GRP78, a major ER chaperone). We found that knockdown of CEMIP inhibited cell proliferation and induced a G1 arrest in SW480 CRC cells...

To reduce embryonic losses in domestic animals for economic production of livestock meat and milk, chemokines and their receptors are required for proper implantation and placentation during early pregnancy. In this study, we investigated the effects of C-C-motif chemokine ligand 23 (CCL23) on the proliferation of bovine endometrial (BEND) epithelial cells. CCL23 treatment improved BEND cell proliferation by enhancing PCNA and cyclin D1 expression via activation of the PI3K/AKT and MAPK signaling pathways. In addition, a combination of CCL23 and tunicamycin reversed the ER stress-induced reduction in cell proliferation and the decreased expression of UPR-mediated signaling proteins, including IRE1α, PERK, and ATF6α...

Achiral Mannich-type curcumin analogs have been synthetized and assayed for their cytotoxic activity. The anti-proliferative and cytotoxic activity of curcuminoids has been tested on human non-small-cell lung carcinoma (A549), hepatocellular carcinoma (HepG2) and pancreatic cancer cell line (PANC-1). Based on the highest anti-proliferative activity nine drug candidates were further tested and proved to cause phosphatidylserine exposure as an early sign of apoptosis. Curcumin analogs with the highest apoptotic activity were selected for mechanistic studies in the most sensitive PANC-1 cells...

AIMS/HYPOTHESIS: Obesity and type 2 diabetes are concomitant with low-grade inflammation affecting insulin sensitivity and insulin secretion. Recently, the thioredoxin interacting protein (TXNIP) has been implicated in the activation process of the NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome. In this study, we aim to determine whether the expression of TXNIP is altered in the circulating immune cells of individuals with type 2 vs type 1 diabetes and whether this can be related to specific causes and consequences of inflammation...

HIV-1 clades are known to be one of the key factors implicated in modulating HIV-associated neurocognitive disorders. HIV-1 B and C clades account for the majority of HIV-1 infections, clade B being the most neuropathogenic. The mechanisms behind HIV-mediated neuropathogenesis remain the subject of active research. We hypothesized that HIV-1 gp120 clade B and C proteins may exert differential proliferation, cell survival and NeuroAIDS effects in human astrocytoma cells via the Unfolded Protein Response, an endoplasmic reticulum- based cytoprotective mechanism...

Studies suggest that tunicamycin may work as a therapeutic drug to cancer cells by inducing stress in the endoplasmic reticulum (ER) through unfolded protein response (UPR) and thereby promoting apoptosis. However, mechanisms of the prolonged activation of the UPR under sustained ER stress in the regulation of cell apoptosis are largely unknown. To delineate the role of candidate genes in the apoptotic process under ER stress and to search for new therapeutic strategies to treat metastatic castration resistant prostate cancer, we performed whole genome expression microarray analysis in tunicamycin treated metastatic androgen-insensitive prostate cancer cells, PC-3...

The unfolded protein response (UPR) is a highly evolutionarily conserved response to endoplasmic reticulum (ER) stress, which functions to return cells to homeostasis or send them into apoptosis, depending on the degree of cellular damage. β-N-methylamino-L-alanine (L-BMAA) has been shown to induce ER stress in a variety of models and has been linked to several types of neurodegenerative disease including Guamanian amyotrophic lateral sclerosis/Parkinsonism dementia complex (ALS/PDC). L-Serine, an amino acid critical for cellular metabolism and neurological signaling, has been shown to be protective against L-BMAA-induced neurotoxicity in both animal and cell culture models...

The recent generation of induced pluripotent stem cells (iPSCs) from a patient with Parkinson's disease (PD) resulting from triplication of the α-synuclein (SNCA) gene locus allows unprecedented opportunities to explore its contribution to the molecular pathogenesis of PD. We used the double-nicking CRISPR/Cas9 system to conduct site-specific mutagenesis of SNCA in these cells, generating an isogenic iPSC line with normalized SNCA gene dosage. Comparative gene expression analysis of neuronal derivatives from these iPSCs revealed an ER stress phenotype, marked by induction of the IRE1α/XBP1 axis of the unfolded protein response (UPR) and culminating in terminal UPR activation...

Chronic arsenic exposure is associated with the development of several cardiovascular (CV) diseases, including hypertension, carotid atherosclerosis and microvascular abnormalities. Upregulation of systemic and aortic angiotensin II (ANGII) signaling has been proposed to contribute to arsenic-induced vascular dysfunction. However, the underlying mechanisms of ANGII signaling augmentation and of the attendant pathological effects on the CV system induced by arsenic remain largely unknown. Here, we reported that exposure of human umbilical vein endothelial cells (HUVECs) to arsenite resulted in elevation of angiotensinogen (AGT, the precursor of ANGII), angiotensin-converting enzyme (ACE, the enzyme critical for ANGII generation) and ANGII type I receptor (AT1R) synthesis as well as increased ANGII production...

Bone remodeling is a balanced process between bone synthesis and degradation, maintaining homeostasis and a constant bone mass in adult life. Imbalance will lead to conditions such as osteoporosis or hyperostosis. Osteoblasts build bone, becoming embedded in bone matrix as mature osteocytes. Osteocytes have a role in sensing and translating mechanical loads into biochemical signals, regulating the differentiation and activity of osteoblasts residing at the bone surface through the secretion of Sclerostin (SOST), an inhibitor of WNT signaling...

Calcium (Ca2+) is a fundamental regulator of cell signaling and function. Thapsigargin (Tg) blocks the sarco/endoplasmic reticulum (ER) Ca2+-ATPase (SERCA), disrupts Ca2+ homeostasis, and causes cell death. However, the exact mechanisms whereby SERCA-inhibition induces cell death are incompletely understood. Here, we report that low (0.1 μM) concentrations of Tg and Tg analogs with various long-chain substitutions at the O(8) position extensively inhibit SERCA1a-mediated Ca2+ transport. We also found that in both prostate and breast cancer cells, exposure to Tg or Tg analogs for 1 day caused extensive drainage of the ER Ca2+ stores...

The unfolded protein response (UPR) adjusts the cell's protein folding capacity in the endoplasmic reticulum (ER) according to need. IRE1 is the most conserved UPR sensor in eukaryotic cells. It has remained controversial, however, whether mammalian and yeast IRE1 use a common mechanism for ER stress sensing. Here, we show that similar to yeast, human IRE1α's ER-lumenal domain (hIRE1α LD) binds peptides with a characteristic amino acid bias. Peptides and unfolded proteins bind to hIRE1α LD's MHC-like groove and induce allosteric changes that lead to its oligomerization...

Stress and misfolded proteins result to dysfunction in the cell, often leading to neurodegenerative diseases and aging. Misfolded proteins form toxic aggregates that threaten cell's stability and normal functions. In order to restore its homeostasis, the cell activates the UPR system. Leading role in the restoration play the molecular chaperones which target the misfolded proteins with the purpose of either helping them to unfold and refold to their natural state or lead them degradation. This paper aims to present some of the most known molecular chaperones and their relation with diseases associated to protein misfolding and neurodegeneration, as well as the role of chaperones in proteostasis...

Progress has been made in our understanding of the mechanisms of endoplasmic reticulum (ER) proteostasis, ER stress and the unfolded protein response (UPR), as well as ER stress-induced autophagy, in the kidney. Experimental models have revealed that disruption of the UPR, including a protein that senses misfolded proteins (namely, inositol-requiring enzyme 1α) in mouse podocytes causes podocyte injury and albuminuria as mice age. Protein misfolding and ER stress are evident in various renal diseases, including primary glomerulonephritides, glomerulopathies associated with genetic mutations, diabetic nephropathy, acute kidney injury, chronic kidney disease and renal fibrosis...

Radish (Raphanus sativus) is an important cruciferous root crop with a close relationship to Chinese cabbage (Brassica rapa). RT-qPCR is used extensively to evaluate the expression levels of target genes, and accurate measurement of target gene expression with this method is determined by the valid reference genes used for data nomalization in different experimental conditions. Screening for appropriate reference genes with stable expression based on RT-qPCR data is important for gene expression and functional analysis research in radish and its relatives...

Preeclampsia (PE) is a placenta disease, featured by hypertension, proteinuria and other multi-organ dysfunctions, and its etiology is unclear. We and others have shown that intensive ER stress and unfolded protein response (UPR) occur in the PE placenta. In this study, we isolated detergent-insoluble proteins (DIPs) from human placenta tissues, which were enriched with protein aggregates, to characterize the placenta UPR in PE. With data-independent acquisition (DIA) mass spectrometry, we identified 2066 DIPs across all normal (n=10) and PE (n=10) placenta samples, among which 110 and 108 DIPs were significantly up- and down- regulated in PE, respectively...

Metformin, the most used drug for the treatment of diabetes type 2 patients, has been shown to have anti-cancer properties. In this study, we found that metformin induced apoptosis in Primary Effusion Lymphoma (PEL) cells, an aggressive B cell lymphoma associated with KSHV against which the conventional therapies usually fail. The cytotoxic effect of metformin correlated with intracellular reactive oxygen species reduction, activation of AMPK, the inhibition of pro-survival pathways such as mTOR and STAT3 and the down-regulation of v-FLIP, a latent viral antigen that also plays a pivotal role in PEL cell survival...