Linking membrane dynamics and trafficking to autophagy and the unfolded protein response

Cellular stressors typically induce two protective counter‐responses—autophagy and the unfolded protein response (UPR). It is conceivable that these two endoplasmic reticulum (ER) membrane‐based processes would intersect/interact somehow with the constitutive housekeeping process of exocytic membrane traffic from the ER. How exactly might this occur? Recent evidence indicates that a conserved Rab protein, Rab1/Ypt1p, has functional roles in UPR and autophagy. This molecular switch and its associated effectors may therefore serve to link up a network of cellular responses to stress through changes in membrane dynamics and protein turnover. The notion provides further explanations as to why elevation of Rab1/Ypt1p levels could counter the cytotoxicity of α‐synuclein, and a similar mode of protection may well be at work against other stresses. J. Cell. Physiol. 228: 1638–1640, 2013. © 2013 Wiley Periodicals, Inc.     

Activation and promotion of adipose stem cells by tumour necrosis factor‐alpha preconditioning for bone regeneration

There is a major medical need for developing novel and effective approaches for repairing non‐union and critical‐sized bone defects. Although the mechanisms remain to be determined, it is known that inflammation plays a crucial role in initiating bone repair and regeneration. This study investigated the effect of short‐term (3 days) preconditioning with tumor necrosis factor‐alpha (TNF‐α) on proliferation, mobilization, and differentiation of adipose tissue‐derived mesenchymal stem cells (ASCs). We demonstrated that TNF‐α pre‐conditioning increased proliferation, mobilization, and osteogenic differentiation of ASCs and up‐regulated bone morphogenetic protein‐2 (BMP‐2) protein level. BMP‐2 silencing by siRNA partially inhibited osteogenic differentiation of ASCs induced by TNF‐α; BMP‐2 pre‐conditioning also significantly increased osteogenic differentiation of ASCs but the effects were significantly smaller than those observed for TNF‐α preconditioning. Furthermore, TNF‐α treatment promoted extracellular‐signal‐regulated kinases(Erk)1/2 and p38 mitogen‐activated protein kinase (MAPK) signaling pathways, but only Erk1/2 inhibition reduced the BMP‐2 levels and osteogenic differentiation induced by TNF‐α preconditioning. Together, these results support the hypothesis that inflammation contributes to bone regeneration by promoting proliferation, mobilization, and osteogenic differentiation of ASCs; 3 days of TNF‐α preconditioning, mimicking the short boost of inflammation normally occurring after bone injury, might serve as a feasible approach for directing stem cells into osteogenic differentiation. J. Cell. Physiol. 9999: XX–XX, 2013. © 2013 Wiley Periodicals, Inc. J. Cell. Physiol. 228: 1737–1744, 2013. © 2013 Wiley Periodicals, Inc.     

Cell proliferation is promoted by compressive stress during early stage of chondrogenic differentiation of rat BMSCs

The presence of an appropriate number of viable cells is prerequisite for successive differentiation during chondrogenesis. Chondrogenic differentiation has been reported to be influenced by mechanical stimuli. This research aimed to study the effects of cyclic compressive stress on cell viability of rat bone marrow‐derived MSCs (BMSCs) during chondrogenesis as well as its underlying mechanisms. The results showed that dynamic compression increased cell quantity and viability remarkably in the early stage of chondrogenesis, during which the expression of Ihh, Cyclin D1, CDK4, and Col2α1 were enhanced significantly. Possible signal pathways implicated in the process were explored in our study. MEK/ERK and p38 MAPK were not found to function in this process while BMP signaling seemed to play an important role in the mechanotransduction during chondrogenic proliferation. In conclusion, dynamic compressive stress could enhance cell viability during chondrogenesis, which might be achieved by activating BMP signaling. J. Cell. Physiol. 228: 1935–1942, 2013. © 2013 Wiley Periodicals, Inc.     

Characterization of photodynamic therapy responses elicited in A431 cells containing intracellular organelle‐localized photofrin

Photodynamic therapy (PDT), a photochemotherapeutic regimen used to treat several diseases, including cancer, exerts its effects mainly through induction of cell death. Using human epidermoid carcinoma A431 cells as a model, we previously showed that distinct cell death types could be triggered by protocols that selectively delivered Photofrin (a clinically approved photosensitizer) to different subcellular sites (Hsieh et al. [2003] J Cell Physiol 194: 363–375]. Here, the responses elicited by PDT in A431 cells containing intracellular organelle‐localized Photofrin were further characterized. Two prominent cell phenotypes were observed under these conditions: one characterized by perinuclear vacuole (PV) formation 2–8 h after PDT followed by cell recovery or shrinkage within 48 h, and a second characterized by typical apoptotic features appearing within 4 h after PDT. DCFDA‐sensitive reactive oxygen species formed proximal to PVs during the response to PDT, covering areas in which both endoplasmic reticulum (ER) and the Golgi complex were located. Biochemical analyses showed that Photofrin‐PDT also induced JNK activation and altered the protein secretion profile. A more detailed examination of PV formation revealed that PVs were derived from the ER. The alteration of ER structure induced by PDT was similar to that triggered by thapsigargin, an ER Ca²⁺‐ATPase inhibitor that perturbs Ca²⁺ homeostasis, suggesting a role for Ca²⁺ in the formation of PVs. Microtubule dynamics did not significantly affect PV formation. This study demonstrates that cells in which intracellular organelles are selectively loaded with Photofrin mount a novel response to ER stress induced by PDT. J. Cell. Biochem. 111: 821–833, 2010. © 2010 Wiley‐Liss, Inc.     

Autophagy and ionizing radiation in tumors: The “survive or not survive” dilemma

Autophagy is a so‐called “self‐eating” system responsible for degrading long‐lived proteins and cytoplasmic organelles, whose products are recycled to maintain cellular homeostasis. This ability makes autophagy a good candidate for a survival mechanism in response to several stresses, including the tumor cell transformation. In particular, recent studies suggested that autophagy functions as a pro‐death mechanism within different tumor contexts. It is, however, widely reported that autophagy represents both a survival mechanism or contributes directly to cell death fate. This interplay of the autophagy functions has been observed in many types of cancers and, in some cases, autophagy has been demonstrated to both promote and inhibit antitumor drug resistance. From a therapeutical point of view, the effects of the modulation of the tumor cell autophagic status, in response to ionizing radiations, are presently of particular relevance in oncology. Accordingly, this review also provides a perspective view on future works for exploring the modulation of autophagic indices in tumor cells as a novel molecular‐based adjuvant strategy, in order to improve radiotherapy and chemotherapy effects in cancer patients. J. Cell. Physiol. 228: 1–8, 2013. © 2012 Wiley Periodicals, Inc.     

The decline and fall of the IGF‐I receptor

This review examines the effect of targeting the insulin‐like growth factor 1 receptor (IGF‐IR) in human cancers. The results are disappointing. The causes for the failure are discussed, as well as the possible use of the IGF‐IR as a secondary target. J. Cell. Physiol. 228: 675–679, 2013. © 2012 Wiley Periodicals, Inc.     

SIRT1 silencing confers neuroprotection through IGF‐1 pathway activation

The following study demonstrated that, in in vitro differentiated neurons, SIRT1 silencing induced an increase of IGF‐1 protein expression and secretion and of IGF‐1R protein levels which, in turn, prolonged neuronal cell survival in presence of an apoptotic insult. On the contrary, SIRT1 overexpression increased cell death. In particular, IGF‐1 and IGF‐1R expression levels were negatively regulated by SIRT1. In SIRT1 silenced cells, the increase in IGF‐1 and IGF‐1R expression was associated to an increase in AKT and ERK1/2 phosphorylation. Moreover, neuronal differentiation was reduced in SIRT1 overexpressing cells and increased in SIRT1 silenced cells. We conclude that SIRT1 silenced neurons appear more committed to differentiation and more resistant to cell death through the activation of IGF‐1 survival pathway. J. Cell. Physiol. 228: 1754–1761, 2013. © 2013 Wiley Periodicals, Inc.     

Endoplasmic Reticulum Stress Interacts With Inflammation in Human Diseases

The endoplasmic reticulum (ER) is a critical organelle for normal cell function and homeostasis. Disturbance in the protein folding process in the ER, termed ER stress, leads to the activation of unfolded protein response (UPR) that encompasses a complex network of intracellular signaling pathways. The UPR can either restore ER homeostasis or activate pro‐apoptotic pathways depending on the type of insults, intensity and duration of the stress, and cell types. ER stress and the UPR have recently been linked to inflammation in a variety of human pathologies including autoimmune, infectious, neurodegenerative, and metabolic disorders. In the cell, ER stress and inflammatory signaling share extensive regulators and effectors in a broad spectrum of biological processes. In spite of different etiologies, the two signaling pathways have been shown to form a vicious cycle in exacerbating cellular dysfunction and causing apoptosis in many cells and tissues. However, the interaction between ER stress and inflammation in many of these diseases remains poorly understood. Further understanding of the biochemistry, cell biology, and physiology may enable the development of novel therapies that spontaneously target these pathogenic pathways. J. Cell. Physiol. 231: 288–294, 2016. © 2015 Wiley Periodicals, Inc.

     

Conservative treatment of early endometrial cancer

Endometrial cancer is the most common cancer of the female genital tract in Europe and in the United States. Endometrial cancer has increased 21% in incidence since 2008, and the death rate has increased more than 100% over the past two decades. Approximately 15% of patients with endometrial cancer are pre‐menopausal. The aim of this review is to discuss the conservative management of endometrial cancer. A number of studies largely support the conservative treatment of endometrial carcinoma (EC) in women desiring future fertility. We focus on the role of progestin hormonal therapy, including the risks associated with non‐standard care, appropriate candidate selection, expected outcomes, various progestin agents and recommended follow‐up. J. Cell. Physiol. 228: 1154–1158, 2013. © 2012 Wiley Periodicals, Inc.     

Non-classical membrane trafficking processes galore

Dogmatic views of how proteins and other cellular components may traffic within and between eukaryotic cells have been challenged in the past few years. Beyond the classical secretory/exocytic pathway and its established players, other pathways of cell surface membrane transport, generally termed “unconventional secretion,” are now better understood. More insights have also been gleaned on the roles of secreted or shedding microvesicles, either exosomal or ectosomal in origin, in unconventional secretion. Recent works have also revealed key molecular components, particularly the Golgi reassembly stacking protein (GRASP), and the importance of stress‐induced autophagy, in unconventional exocytic transport. This GRASP and autophagy‐dependent (GAD) mode appears to underlie the unconventional exocytosis of many soluble and membrane cargoes. Likewise, recent findings have revealed transport processes that contrast the classically known mitochondria import, namely vesicular transport from the mitochondria to peroxisomes and lysosomes. Mitochondria‐peroxisomal targeting of mitochondria‐derived vesicles appears to involve the retromer complex, which was classically associated with endosome‐Golgi membrane traffic. The routes of intracellular membrane transport and communications between eukaryotic organelles now appear far more complex that one would have imagined 10 years ago. J. Cell. Physiol. 227: 3722–3730, 2012. © 2012 Wiley Periodicals, Inc.     

Amyloid toxicity and platelet‐activating factor signaling

Amyloidosis is the accumulation of insoluble proteinaceous aggregates in vivo and is implicated in many neurodegenerative diseases, including Alzheimer's, Huntington's, and Parkinson's diseases. This article briefly reviews the current knowledge of amyloid aggregate toxicity and inflammatory signaling in the nervous system. In particular, we focus our attention on the role of platelet‐activating factor (PAF) as mediator of amyloid cytotoxicity. J. Cell. Physiol. 228: 1143–1148, 2013. © 2012 Wiley Periodicals, Inc.     

Non insulin producing cell line,MIA PaCa‐2 is rendered insulin producing in vitro via mesenchymal epithelial transition

We used non‐insulin producing pancreatic carcinoma cell line, MIA PaCa‐2 and have modulated its culture conditions by using 1% matrigel as extracellular matrix, N2, B27 growth supplements and serum free conditions. Expression of markers was analyzed using qRT‐PCR, immunofluorescence and in vitro functional assay for insulin and C‐peptide release was assessed using insulin and C‐peptide ELISA, respectively. The cells grown under this altered culture conditions have exhibited a transition in the morphology from mesenchymal to epithelial with extensive piling up of cells. A reduction in doubling time from 40 to 18 h, upregulation of beta islet specific markers like pancreatic duodenal homeobox‐1 (Pdx‐1), C‐peptide, insulin, and disappearance of markers like vimentin were observed. On the functional level, the altered morphology bearing cells released high levels of insulin in response to 10 µM tolbutamide (an activator of insulin pathway) and reduced insulin secretion in response to 50 µM nifedipine (inhibitor of the pathway). On the contrary, the original cells (mesenchymal morphology) had failed to release any insulin in response to varying concentrations of glucose and also the activators and inhibitors of the insulin pathway. This investigation thus provides a basis for using this basic developmental biology phenomenon mesenchymal to epithelial transition as a strategy to generate a large number of functional islets from stem cells of mesenchymal origin. J. Cell. Biochem. 9999: XX–XX, 2013. © 2013 Wiley Periodicals, Inc. J. Cell. Biochem. 114: 1642–1652, 2013. © 2013 Wiley Periodicals, Inc.     

Decreased expression of autophagic beclin 1 protein in idiopathic pulmonary fibrosis fibroblasts

Autophagy is the main cellular pathway for degradation of long‐lived proteins and organelles and regulates cell fate in response to stress. Beclin 1 is a key regulator of this process. In some settings autophagy and apoptosis seem to be interconnected. Recent reports indicate that fibroblasts in idiopathic pulmonary fibrosis (IPF) acquire resistance to apoptosis. Here, we examined the expression of beclin 1, and of the anti apoptotic protein Bcl‐2 in human IPF fibroblasts using immunohistochemistry and molecular biology in bioptic sections, in primary cultures of fibroblasts taken from patients with IPF and in fibroblast cell lines. Expression of beclin 1 in fibroblasts from IPF was down‐regulated in comparison with fibroblasts from normal lungs while the anti‐apoptotic protein Bcl‐2 expression was over‐expressed. Treatment of fibroblast cell cultures with cisplatin induced a significant increase in beclin 1 and caspase 3 protein levels but a reduction in Bcl‐2 expression. These observations were confirmed by the analysis of acid compartments and transmission electron microscopy. Our results demonstrate a modified expression of the apoptotic beclin 1 Bcl‐2 proteins in human IPF fibroblasts suggesting the existence of an autophagy/apoptosis system dysfunction. J. Cell. Physiol. 228: 1516–1524, 2013. © 2012 Wiley Periodicals, Inc.     

Shear flow-induced formation of tubular cell protrusions in multiple myeloma cells

Exposure of live cells to shear flow induces major changes in cell shape, adhesion to the extracellular matrix, and migration. In the present study, we show that exposure of cultured multiple myeloma (MM) cells to shear flow of 4–36 dynes/cm² triggers the extension of long tubular protrusions (denoted flow‐induced protrusions, or FLIPs) in the direction of the flow. These FLIPs were found to be rich in actin, contain few or no microtubules and, apart from endoplasmic reticulum (ER)‐like membranal structures, are devoid of organelles. Studying the dynamics of this process revealed that FLIPs elongate at their tips in a shear force‐dependent manner, and retract at their bases. Examination of this force dependence revealed considerable heterogeneity in the mechanosensitivity of individual cells, most likely reflecting the diversity of the malignant B cell population. The mechanisms underlying FLIP formation following mechanical perturbation, and their relevance to the cellular trafficking of MM cells, are discussed. J. Cell. Physiol. 226: 3197–3207, 2011. © 2011 Wiley Periodicals, Inc.     

Disruption of immune regulation by microbial pathogens and resulting chronic inflammation

Activation of the immune response is a tightly regulated, coordinated effort that functions to control and eradicate exogenous microorganisms, while also responding to endogenous ligands. Determining the proper balance of inflammation is essential, as chronic inflammation leads to a wide array of host pathologies. Bacterial pathogens can instigate chronic inflammation via an extensive repertoire of evolved evasion strategies that perturb immune regulation. In this review, we discuss two model pathogens, Mycobacterium tuberculosis and Porphyromonas gingivalis, which efficiently escape various aspects of the immune system within professional and non‐professional immune cell types to establish chronic inflammation. J. Cell. Physiol. 228: 1413–1422, 2013. © 2012 Wiley Periodicals, Inc.     

Resistin protects against 6‐hydroxydopamine‐induced cell death in dopaminergic‐like MES23.5 cells

Resistin is originally reported as an adipose tissue‐specific hormone and is thought to represent a link between obesity and insulin‐resistant diabetes. Adipokines exert energy‐regulation and has been reported to have neuroprotective effect like leptin, adiponectin, and ghrelin. However, the role of resistin in neuroprotective effect has not been explored. 6‐hydroxydopamine (6‐OHDA), one of the most investigated Parkinson's disease neurotoxins, is widely used to study mechanisms of cell death in dopaminergic neurons. In the present study, our results show that treatment of resistin protects 6‐OHDA‐induced cell death in dopaminergic‐like MES23.5 cells. Resistin also antagonizes 6‐OHDA‐induced apoptotic cell death measured by fluorescence‐activated cell sorter (FACS) analysis and Hochest 33342 staining. Furthermore, treatment of resistin also dramatically reduces 6‐OHDA‐mediated ROS production and mitochondria transmembrane potential dissipation. Moreover, expression of 6‐OHDA‐induced apoptotic markers, such as Bcl‐2 degradation, Bax expression, PARP degradation and caspase 3 activity increase, are all attenuated by resistin treatment. Our results also show that resistin induces up‐regulation of heat shock protein (Hsp) 32 (heme oxygenase‐1, HO‐1) and Hsc (heat shock cognate) 70. The protective effect of resistin on 6‐OHDA‐induced cell death is abolished by HO‐1 inhibitor zinc protoporphyrin IX and HSP inhibitor KNK437. These results suggest the neuroprotective effects of resistin against 6‐OHDA‐induced cell death with the underlying mechanisms of inhibiting oxidative stress and apoptosis. Therefore, we suggest that resistin may provide a useful therapeutic strategy for neurodegenerative diseases such as Parkinson's disease. J. Cell. Physiol. 228: 563–571, 2013. © 2012 Wiley Periodicals, Inc.     

Resveratrol induces apoptosis of human nasopharyngeal carcinoma cells via activation of multiple apoptotic pathways

Resveratrol, a naturally occurring dietary compound with chemopreventive properties has been reported to trigger a variety of cancer cell types to apoptosis. Whether resveratrol shows any activity on human nasopharyngeal carcinoma (NPC) cells remained to be determined. The aim of this study was to investigate the effect and mechanism of resveratrol on human NPC cells. Treatment of resveratrol resulted in significant decrease in cell viability of NPC cell lines in a dose‐ and time‐dependent manner. A dose‐dependent apoptotic cell death was also measured by flow cytometery analysis. Molecular mechanistic studies of apoptosis unraveled resveratrol treatment resulted in a significant loss of mitochondrial transmembrane potential, release of cytochrome c, enhanced expression of Fas ligand (FasL), and suppression of glucose‐regulated protein 78 kDa (GRP78). These were followed by activation of caspases‐9, ‐8, ‐4, and ‐3, subsequently leading to DNA fragmentation and cell apoptosis. Furthermore, up‐regulation of proapoptotic Bax and down‐regulation of antiapoptotic Bcl‐2 protein were also observed. Taken together, resveratrol induces apoptosis in human NPC cells through regulation of multiple apoptotic pathways, including death receptor, mitochondria, and endoplasmic reticulum (ER) stress. Resveratrol can be developed as an effective compound for human NPC treatment. J. Cell. Physiol. 226: 720–728, 2011. © 2010 Wiley‐Liss, Inc.     

Features that determine telomere homolog oligonucleotide‐induced therapeutic DNA damage‐like responses in cancer cells

The article to which this erratum refers was published in J Cell Physiol (2007) 210:582–595. J. Cell. Physiol. 215: 285, 2008. © 2007 Wiley‐Liss, Inc.