Homers are scaffolding proteins that bind Ca 2+ signaling proteins in cellular microdomains. The Homers participate in targeting and localization of Ca 2+ signaling proteins in signaling complexes. However, recent work showed that the Homers are not passive scaffolding proteins, but rather they regulate the activity of several proteins within the Ca 2+ signaling complex in an isoform specific manner. Homer2 increases the GAP activity of RGS proteins and PLCβ that accelerate the GTPase activity of Gα subunits. Homer1 gates the activity of TRPC channels, controls the rates of their translocation and retrieval from the plasma membrane and mediates the conformational coupling between TRPC channels and IP 3 Rs. Homer1 stimulates the activity of the cardiac and neuronal Ltype Ca 2+ channels Ca v 1.2 and Ca v 1.3. Homer1 also mediates the communication between the cardiac and smooth muscle ryanodine receptor RyR2 and Ca v 1.2 to regulate E-C coupling. In many cases the Homers function as a buffer to reduce the intensity of Ca 2+ signaling and create a negative bias that can be reversed by the immediate early gene form of Homer 1. Hence, the Homers should be viewed as the buffers of Ca 2+ signaling that ensure a high spatial and temporal fidelity of the Ca 2+ signaling and activation of downstream effects.

Myoglobin is an oxygen storage molecule that is selectively expressed in cardiac and slow-twitch skeletal muscles that have a high oxygen demand. Numerous studies have implicated hypoxia in the regulation of myoglobin expression as an adaptive response to hypoxic stress. However, the details of this relationship remain undefined. In the present study, adult mice exposed to 10% oxygen for periods up to 3 wk exhibited increased myoglobin expression only in the working heart, whereas myoglobin was either diminished or unchanged in skeletal muscle groups. In vitro and in vivo studies revealed that hypoxia in the presence or absence of exercise-induced stimuli reprograms calcium signaling and modulates myoglobin gene expression. Hypoxia alone significantly altered calcium influx in response to cell depolarization or depletion of endoplasmic reticulum calcium stores, which inhibited the expression of myoglobin. In contrast, our whole animal and transcriptional studies indicate that hypoxia in combination with exercise enhanced the release of calcium from the sarcoplasmic reticulum via the ryanodine receptors triggered by caffeine, which increased the translocation of nuclear factor of activated T-cells into the nucleus to transcriptionally activate myoglobin expression. The present study unveils a previously unrecognized mechanism where the hypoxia-mediated regulation of calcium transients from different intracellular pools modulates myoglobin gene expression. In addition, we observed that changes in myoglobin expression, in response to hypoxia, are not dependent on hypoxia-inducible factor-1 or changes in skeletal muscle fiber type. These studies enhance our understanding of hypoxia-mediated gene regulation and will have broad applications for the treatment of myopathic diseases. nuclear factor of activated T cells; calcineurin; skeletal muscle MYOGLOBIN IS A CYTOPLASMIC hemoprotein that is abundantly expressed in heart and oxidative skeletal myofibers. Elegant studies using physiological, biochemical, and spectroscopic analyses support an important role for myoglobin in facilitated oxygen transport, as a reservoir for oxygen and as a scavenger of reactive oxygen species in the mammalian heart and skeletal muscle (6,16,20,34,35,39). Detailed transcriptional analyses have been undertaken to define upstream activation motifs including a CCAC box, A/T element, nuclear factor of activated T cells (NFAT) response element, and E boxes that are necessary for muscle-specific transcription of the myoglobin gene (4,5,21,22). Following differentiation, myoglobin expression is coordinately regulated by neural and muscular activities that stimulate calcium signaling within the cell. Stimuli that enhance intracellular calcium levels increase activity and gene expression of calcineurin, a Ca 2ϩ /calmodulindependent serine phosphatase (13,47,48). Upon activation, calcineurin dephosphorylates the transcription factor NFAT, which translocates to the nucleus and combinatorially interacts with other transcription factors to regulate myo...

This study aimed to investigate KIF18A expression in hepatocellular carcinoma (HCC) and to determine the possibility of KIF18A expression being a biomarker in HCC diagnosis or being an independent predictor of disease-free survival (DFS) and overall survival (OS) in HCC patients underwent surgical resection. KIF18AmRNA was detected in 216 cases of HCC tissues by quantitative real-time PCR (qRT-PCR) and in 20 cases of HCC tissues by semi-quantitative RT-PCR. KIF18A protein was determined in 32 cases of HCC tissues by immunohistochemistry (IHC). The survival probability was analyzed by Kaplan-Meier method, and survival curves between groups were obtained by using the log-rank test. Independent predictors associated with DFS were analyzed with Stepwise Cox proportional hazard models. High KIF18A mRNA level was detected in 154 out of 216 (71.3%) cases of HCC. The positive rate of KIF18A expression was significantly higher in liver cancer tissues than that in adjacent normal liver tissues (ANLT) from HCC patients [65.6% (21 of 32) vs. 25.0% (8 of 32), P=0.001]. The KIF18A expression level had positive relevance to the alpha-fetoprotein (AFP) (≥200 ng/ml), tumor size (≥5cm), clinical tumor-node-metastasis (TNM) stage and portal vein tumor thrombus (PVTT) in HCC (all P <0.05). A survival analysis indicated that HCC patients with higher KIF18A expression had a significantly shorter DFS and OS after resection. A multivariate analysis suggested that KIF18A upregualtion was an independent factor for DFS [hazard risk (HR)=1.602; 95% confidence interval (CI), 1.029-2.579; P=0.031] and OS (HR=1.682; 95% CI, 1.089-2.600; P=0.019). KIF18A might be a biomarker for HCC diagnosis and an independent predictor of DFS and OS after surgical resection.

Anticancer agents that present nonapoptotic cell death pathways are required for treating apoptosis-resistant pancreatic cancer. Here, we synthesized three fluorescent dithiocarbazate–copper complexes, {[CuII(L)­(Cl)] 1, [CuII 2(L)2(NO3)2] 2, and [CuII 2CuI(L)2(Br)3] 3}, to assess their antipancreatic cancer activities. Complexes 1–3 showed significantly greater cytotoxicity toward several pancreatic cancer cell lines with better IC50 than those of the HL ligand and cisplatin. Confocal fluorescence imaging showed that complex 3 was primarily localized in the mitochondria. Primarily, compound 3 also can be applied to in vivo imaging. Further studies revealed that complex 3 kills pancreatic cancer cells by triggering multiple mechanisms, including ferroptosis. Complex 3 is the first copper complex to evoke cellular events consistent with ferroptosis in cancer cells. Finally, it significantly retarded the ASPC-1 cells’ growth in a mouse xenograft model.

The aim of the present study was to investigate the role of the Toll-like receptor (TLR)4 signaling pathway in cellular response to lipopolysaccharide (LPS) in rat pulmonary artery smooth muscle cells (PASMCs). Chronic obstructive pulmonary disease (COPD) rats were established with passive inhaling cigarette smoke plus injection of LPS. The TLR4 protein in lung tissues was determined with immunohistochemical staining and protein levels of the components of the TLR4 pathway in PASMCs were analyzed with western blotting. The production of interferon (IFN)-γ upon LPS stimulation in PASMCs was measured with ELISA. TLR4 expression in lung tissue from COPD rats was increased obviously compared with that in normal group. LPS enhances TLR4 expression in rat PASMCs and induced production of IFN-γ dramatically. LPS treatment resulted in increased phosphor-interleukin-1 receptor-associated kinase (IRAK), IκB and IκB kinase, as well as the total protein of nuclear factor (NF)-κB p65. TLR4 inhibitor TAK-242, IRAK1/4 inhibitor and NF-κB inhibitor Bay 117082 were capable of suppressing the effects of LPS. TLR4 signaling pathway is functional in PASMCs, and may be involved in the inflammatory response during the pathogenesis of COPD.