The intracellular distribution of regulatory molecules may provide a mechanism for controlling gene expression. The subcellular location of cAMP-dependent protein kinase was analyzed in living cells by microinjection of regulatory and catalytic subunits labeled with fluorescein. Following microinjection, type I holoenzyme was found in the cytoplasm and remained there for up to 4 hr. Upon dissociation of holoenzyme with 8-bromo-cAMP, free catalytic subunit appeared in the nucleus while regulatory subunit remained in the cytoplasm. Similarly, purified catalytic subunit was transported to the nucleus in the absence of elevated intracellular cAMP following its introduction into the cytoplasm. Translocation to the nucleus was apparent within 10 min and persisted for at least 2 hr. In contrast, purified regulatory subunit, like holoenzyme, was maintained in the cytoplasm. These results suggest that one function of the type I regulatory subunit is to serve as a cytoplasmic anchor, sequestering the catalytic subunit in the cytoplasm until holoenzyme dissociates in response to increased cAMP.Cells can respond to extracellular signals through the action of cell surface receptors and second-messenger pathways. One of the best characterized second-messenger systems in eukaryotic cells is the cAMP-mediated system that leads to the activation of cAMP-dependent protein kinase, cAPK (1). In unstimulated cells, cAPK exists predominantly as an inactive holoenzyme consisting of two regulatory subunits and two catalytic subunits (2). Following an increase in intracellular cAMP, the regulatory subunits bind cAMP, thus causing dissociation of the holoenzyme complex and the production of active monomeric catalytic subunits.At least two types of holoenzymes, types I and II, exist in most cells. The holoenzyme classification is based on the regulatory subunits, also referred to as type I and type II (3-5). Type II holoenzymes are autophosphorylated on the regulatory subunit (3), whereas type I holoenzymes have a high-afflinity binding site for MgATP (4). The amount of cAPK I and II varies between different tissues (6), and the two types of holoenzyme partition differentially between soluble and particulate fractions in the same cell (7, 8). The significance of the different types of regulatory subunits is unclear, but it has been proposed that the regulatory subunit functions in processes other than the inhibition of the catalytic subunit. For example, the type II regulatory subunit binds tightly to other proteins such as microtubule-associated protein 2 (9, 10) and a 150-kDa protein in brain (11). While both the catalytic and regulatory subunits of cAPK have been postulated to play a role in the transcriptional regulation of cAMP-responsive genes (12, 13), more recent studies indicate that the catalytic subunit is both necessary and sufficient for this response (14,15,36,37). Although it seems clear that phosphorylation of key substrates by the catalytic subunit plays a critical role in the transcriptional response to cAMP, it ...

Our findings suggest that IL-6 levels are associated with cluster symptoms in cancer patients. Clinicians should identify patients at risk for more severe symptoms and formulate novel target interventions to improve symptom management.

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PurposeLong noncoding RNA nuclear paraspeckle assembly transcript 1 (NEAT1) has been deemed an oncogene in many human cancers. However, the underlying mechanism of NEAT1 in nasopharyngeal carcinoma (NPC) progression remains largely unclear.Materials and MethodsQuantitative real-time PCR assay was performed to assess the expression of NEAT1 and miR-34a-5p in NPC tissues and cells. Western blot analysis was used to observe cell epithelial to mesenchymal transition (EMT) and the activation of Wnt/β-catenin signaling in 5-8F cells. MiRNA directly interacting with NEAT1 were verified by dual-luciferase reporter assay and RNA immunoprecipitation. Cell proliferation ability was determined by CCK-8 assay, and cell migration and invasion capacities were assessed by transwell assays. An animal model was used to investigate the regulatory effect of NEAT1 on tumor growth in vivo.ResultsOur data revealed that NEAT1 is upregulated, while miR-34a-5p is downregulated in NPC tissues and cell lines. NEAT1 knockdown repressed tumor growth in vitro and in vivo. Additionally, we discovered that NEAT1 directly binds to miR-34a-5p and suppresses miR-34a-5p expression. Moreover, NEAT1 knockdown exerted suppression effects on cell proliferation, migration, invasion, and EMT by miR-34a-5p. NEAT1 knockdown blocked Wnt/β-catenin signaling via miR-34a-5p.ConclusionOur study demonstrated that NEAT1 targets miR-34a-5p at least partly to drive NPC progression by regulating Wnt/β-catenin signaling, suggesting a potential therapeutic target for NPC.