SignificanceParkinson’s disease (PD) is a chronic dopamine (DA) neuron degenerative disorder. Little is known about factors that impact vulnerability of DA neurons to pathological insults. In this study, we found that vesicular glutamate transporter 2 (VgluT2) expression may play an important role in protecting DA neurons. Selective deletion of VgluT2 in DA neurons led to a significant reduction in expression of brain-derived neurotrophic factor and its receptor tyrosine receptor kinase B and a significant increase in DA neuron death caused by the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. Restoration of VgluT2 expression in DA neurons reversed these alterations. These findings suggest that reduced VgluT2 expression in DA neurons may constitute a risk factor in the development of PD and suggest potential therapeutic strategies for boosting resilience of DA neurons.

Gastrin, a gastrointestinal hormone responsible for gastric acid secretion, has been confirmed as a growth factor for gastrointestinal tract malignancies. High expression of gastrin mRNA was observed in pancreatic and colorectal cancer; however, the mechanism is unclear. Epidermal growth factor (EGF) was found to increase gastrin mRNA stability, indicating mRNA turnover regulation mechanism is involved in the control of gastrin mRNA expression. Using biotinlabeled RNA probe pull-down assay combined with mass spectrometry analysis, we identified the heterogeneous nuclear ribonucleoprotein K (hnRNP K) and poly(C) binding protein 1 (PCBP1) bound with the C-rich region in gastrin mRNA 3 untranslated region. Nucleolin bound with the AGCCCU motif and interacted with hnRNP K were also demonstrated. Under EGF treatment, we observed the amount of nucleolin interacting with hnRNP K and gastrin mRNA increased. Using small interfering RNA technology to define their functional roles, we found hnRNP K, PCBP1, and nucleolin were all responsible for stabilizing gastrin mRNA. Moreover, nucleolin plays a crucial role in mediating the increased gastrin mRNA stability induced by EGF signaling. Besides, we also observed hnRNP K/PCBP1 complex bound with the C-rich region in the gastrin mRNA increased nucleolin binding with gastrin mRNA. Finally, a novel binding model was proposed. INTRODUCTIONRegulation of gene expression is essential for the homeostasis of an organism. Transcriptional regulation is well documented in controlling gene expression; however, it is becoming increasingly clear that regulation of mRNA decay rates is also an important control point in determining the abundance of cellular transcripts (Wilusz et al., 2001;Wilusz and Wilusz, 2004). The aberrant control of mRNA turnover has been implicated in disease states, including cancer, chronic inflammatory responses, and coronary disease (Hollams et al., 2002;Audic and Hartley, 2004). For example, in myeloma and human T-cell leukemia, the c-myc gene is mutated due to a translocation or loss of the 3Ј untranslated regions (UTRs). This renders the c-myc mRNA up to 7 times more stable than the wild type (Hollis et al., 1988;Aghib et al., 1990). mRNA turnover rate is mainly specified by control elements that are usually located within the 3ЈUTR of mRNAs and they are recognized by various RNA-binding proteins. The most well studied specific cis-acting element controlling the half-life of mRNA is the adenylate-and uridylate-rich (AU-rich) element (ARE) found in 3ЈUTR of a variety of short-lived mRNAs, including those encoding cytokines, lymphokines, proto-oncogenes, and growth factors (Chen and Shyu, 1995;Wilusz et al., 2001). A plethora of AREbinding proteins have been identified, characterized, and cloned, including AUF1, HuR, TIA-1, and tristetraprolin, which exerted either negative or positive effects on mRNA stability (Brennan and Steitz, 2001;Bevilacqua et al., 2003). C-rich element has also been reportedly involved in the regulation of mRNA stability. Three discontinuo...

After sudden traumatic brain injuries, secondary injuries may occur during the following days or weeks, which leads to the accumulation of reactive oxygen species (ROS). Since ROS exacerbate brain damage, it is important to protect neurons against their activity. Zinc finger protein 179 (Znf179) was shown to act as a neuroprotective factor, but the regulation of gene expression under oxidative stress remains unknown. In this study, we demonstrated an increase in Znf179 protein levels in both in vitro model of hydrogen peroxide (H2O2)-induced ROS accumulation and animal models of traumatic brain injury. Additionally, we examined the sub-cellular localization of Znf179, and demonstrated that oxidative stress increases Znf179 nuclear shuttling and its interaction with specificity protein 1 (Sp1). Subsequently, the positive autoregulation of Znf179 expression, which is Sp1-dependent, was further demonstrated using luciferase reporter assay and green fluorescent protein (GFP)-Znf179-expressing cells and transgenic mice. The upregulation of Sp1 transcriptional activity induced by the treatment with nerve growth factor (NGF) led to an increase in Znf179 levels, which further protected cells against H2O2-induced damage. However, Sp1 inhibitor, mithramycin A, was shown to inhibit NGF effects, leading to a decrease in Znf179 expression and lower cellular protection. In conclusion, the results obtained in this study show that Znf179 autoregulation through Sp1-dependent mechanism plays an important role in neuroprotection, and NGF-induced Sp1 signaling may help attenuate more extensive (ROS-induced) damage following brain injury.

Reduction in host-activated protein C levels and resultant microvascular thrombosis highlight the important functional role of protein C anticoagulant system in the pathogenesis of sepsis and septic shock. Thrombomodulin (TM) is a critical factor to activate protein C in mediating the anticoagulation and anti-inflammation effects. However, TM protein content is decreased in inflammation and sepsis, and the mechanism is still not well defined. In this report, we identified that the TM 5 untranslated region (UTR) bearing the internal ribosome entry site (IRES) element controls TM protein expression. Using RNA probe pulldown assay, HuR was demonstrated to interact with the TM 5UTR. Overexpression of HuR protein inhibited the activity of TM IRES, whereas on the other hand, reducing the HuR protein level reversed this effect. When cells were treated with IL-1␤, the IRES activity was suppressed and accompanied by an increased interaction between HuR and TM 5UTR. In the animal model of sepsis, we found the TM protein expression level to be decreased while concurrently observing the increased interaction between HuR and TM mRNA in liver tissue. In summary, HuR plays an important role in suppression of TM protein synthesis in IL-1␤ treatment and sepsis. INTRODUCTIONThere is ample evidence that inflammation and coagulation are intricately related processes, whereby inflammation not only leads to activation of coagulation, but coagulation also markedly affects inflammation activity (Esmon, 2005;Levi and Van der Poll, 2005). Inflammation-induced coagulation contributes to vascular thrombotic disease and is also the major consequence in the pathogenesis of microvascular failure and subsequent multiple organ failure in severe sepsis (Diehl and Borgel, 2005). Both preclinical and clinical studies have suggested that excessive microvascular thrombosis during sepsis results in part from depletion of endogenous anticoagulant systems, such as the heparin-antithrombin system, the protein C anticoagulant pathway, and the tissue factor pathway inhibitor system (Haley et al., 2004).Thrombomodulin (TM) is an important anticoagulant protein present on the surface of vascular endothelial cells (Dittman and Majerus, 1990). TM forms a high-affinity complex with thrombin and results in approximately a 100-fold increase in the activation of protein C to execute anticoagulant effects (Esmon, 1993). Recent studies have shown that TM also plays an important role in attenuation of the inflammatory response (Van de Wouwer and Conway, 2004). One mechanism for TM's anti-inflammatory effect relates to the properties of activated protein C (APC). For example, APC has been found to inhibit endotoxin-induced production of tumor necrosis factor-␣ (TNF-␣), interleukin (IL)-1␤, IL-6, and IL-8 in cultured monocytes/macrophages (Okajima, 2001). TM is also a critical cofactor for thrombin-mediated activation of the thrombin-activatable fibrinolysis inhibitor (TAFI), which is responsible for inactivation of complement factors C3a and C5a to protect against co...

In a subgroup of patients with amyotrophic lateral sclerosis (ALS)/Frontotemporal dementia (FTD), the (G4C2)-RNA repeat expansion from C9orf72 chromosome binds to the Ran-activating protein (RanGAP) at the nuclear pore, resulting in nucleocytoplasmic transport deficit and accumulation of Ran in the cytosol. Here, we found that the sigma-1 receptor (Sig-1R), a molecular chaperone, reverses the pathological effects of (G4C2)-RNA repeats in cell lines and in Drosophila. The Sig-1R colocalizes with RanGAP and nuclear pore proteins (Nups) and stabilizes the latter. Interestingly, Sig-1Rs directly bind (G4C2)-RNA repeats. Overexpression of Sig-1Rs rescues, whereas the Sig-1R knockout exacerbates, the (G4C2)-RNA repeats-induced aberrant cytoplasmic accumulation of Ran. In Drosophila, Sig-1R (but not the Sig-1R-E102Q mutant) overexpression reverses eye necrosis, climbing deficit, and firing discharge caused by (G4C2)-RNA repeats. These results on a molecular chaperone at the nuclear pore suggest that Sig-1Rs may benefit patients with C9orf72 ALS/FTD by chaperoning the nuclear pore assembly and sponging away deleterious (G4C2)-RNA repeats.