Journal of cellular physiology
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The complexity of pemphigus acantholysis together with the weak expression of desmoglein 1 (Dsg1) in cultured keratinocytes have made the study on the pathogenic action of anti-Dsg1 antibodies quite difficult. The pathophysiology of the acantholytic phenomenon could depend on the reduction of Dsg1 adhesion function occurring after its massive internalization or decrease of its synthesis. Here, we have investigated this hypothesis by using sera of patients having antibodies against Dsg1 or monoclonal anti-Dsg1 antibodies to simulate pemphigus autoimmunity in Dsg1-rich keratinocytes. ⋯ However, binding of IgG to Dsg1 did not determine its early depletion from the adhesion complexes but reduced the amount of Dsg1 found in the Triton X-100 soluble pool of proteins. Taken together, our results represent the first demonstration that anti-Dsg1 antibodies induce similar alterations on the subcellular distribution of Dsg1 irrespective of the disease where they come from. Furthermore, the present study provides insight into the mechanisms underlying epithelial blistering observed in the skin type of pemphigus.
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Human intervertebral disc (IVD) degeneration often initiated from the human nucleus pulposus (hNP) with aging leading to IVD destruction and extracellular matrix (ECM) depletion. Previously, we have successfully employed transforming growth factor-beta1 (TGF-beta1) to promote chondrogenesis of mesenchymal progenitor cells (MPCs) and immortalized human mesenchymal stem cells. In this study, we examine the role of TGF-beta1 in platelet-rich plasma (PRP) on disc regeneration, including proliferation, redifferentiation, and the reconstitution of tissue-engineered NP. hNP cells were isolated from volunteers with different ages and cultured in the presence of PRP. ⋯ Immunostaining of type II collagen indicates that PRP participates in chondrogenesis of tissue-engineered NP with collagen scaffolds. We concluded that growth factors in PRP can effectively react as a growth factor cocktail to induce hNP proliferation and differentiation, and also promote tissue-engineered NP formation. These findings are the first to demonstrate that PRP might be a therapeutic candidate for prevention of disc degeneration.
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N-(4-hydroxyphenyl)retinamide (4HPR, fenretinide), a retinoic acid (RA) derivative and a potential cancer preventive agent, is known to exert its chemotherapeutic effects in cancer cells through induction of apoptosis. Earlier work from our laboratory has shown that relatively low concentrations of 4HPR induce neuronal differentiation of cultured human retinal pigment epithelial (ARPE-19) cells (Chen et al., 2003, J Neurochem 84:972-981). However, at higher concentrations of 4HPR, these cells showed morphological changes including cell shrinkage and cell death. ⋯ In addition, the increase in the expression of heme oxygenase-1 (HO-1), a stress response protein, and the growth arrest and DNA damage-inducible transcription factor 153 (Gadd153) in response to the ROS generation were also blocked by these receptor antagonists. Pyrrolidine dithiocarbamate (PDTC), a free-radical scavenger, inhibited 4HPR-induced ROS generation, the expression of its downstream mediator, Gadd153, and apoptosis in the pretreated cells. Therefore, our results, clearly demonstrate that 4HPR induces apoptosis in ARPE-19 cells and that RARs mediate this process by regulating ROS generation as well as the expression of Gadd153 and HO-1.
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Phosphatidylinositol 3-kinase (PI3K)/Akt and nuclear factor-kappa B (NF-kappaB) signaling pathways play a critical role in mediating survival signals. In this study we have investigated how loss of dystrophin (the primary cause of Duchenne muscular dystrophy) modulates the activation of PI3K/Akt and NF-kappaB signaling pathways in skeletal muscle in response to mechanical stimulation. Activation of Akt was significantly higher in diaphragm muscle from dystrophin-deficient mdx mice compared to normal mice at both prenecrotic and necrotic states. ⋯ Mechanical stretch also reduced the interaction of HDAC1 with RelA subunit of NF-kappaB in diaphragm muscle. Finally, cellular levels of Bcl-2, cIAP1, and integrin beta1 and activation of integrin linked kinase were higher in diaphragm muscle of mdx mice compared to normal mice. Taken together, our data suggest that loss of dystrophin and/or mechanical stretch results in the up-regulation of P13K/Akt and NF-kappaB signaling pathways in skeletal muscle.
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A20 was originally characterized as a TNF-inducible gene in human umbilical vein endothelial cells. As an NF-kappaB target gene, A20 is also induced in many other cell types by a wide range of stimuli. Expression of A20 has been shown to protect from TNF-induced apoptosis and also functions via a negative-feedback loop to block NF-kappaB activation induced by TNF and other stimuli. ⋯ Therefore, the protective effect of A20 on mitochondrial apoptotic pathway activated by OxLDL may be dependent on FADD. A20 expression reversed OxLDL-mediated G(0)/G(1) stage arrest by maintaining the expression of cyclin B1, cyclin D1, and cyclin E, and p21 and p73. Thus, A20 expression blocks OxLDL-mediated apoptosis in murine RAW264.7 macrophages through disrupting Fas/FasL-dependent activation of caspase-8 and the mitochondria pathway.