Transcription factors of the NF-kappaB family regulate hundreds of genes in the context of multiple important physiological and pathological processes. NF-kappaB activation depends on phosphorylation-induced proteolysis of inhibitory IkappaB molecules and NF-kappaB precursors by the ubiquitin-proteasome system. Most of the diverse signaling pathways that activate NF-kappaB converge on IkappaB kinases (IKK), which are essential for signal transmission. Many important details of the composition, regulation and biological function of IKK have been revealed in the last years. This review summarizes current aspects of structure and function of the regular stoichiometric components, the regulatory transient protein interactions of IKK and the mechanisms that contribute to its activation, deactivation and homeostasis. Both phosphorylation and ubiquitinatin (destructive as well as non-destructive) are crucial post-translational events in these processes. In addition to controlling induced IkappaB degradation in the cytoplasm and processing of the NF-kappaB precursor p100, nuclear IKK components have been found to act directly at the chromatin level of induced genes and to mediate responses to DNA damage. Finally, IKK is engaged in cross talk with other pathways and confers functions independently of NF-kappaB.

IkappaB kinase complexes: gateways to NF-kappaB activation and transcription.

AQP3 (aquaporin-3), known as an integral membrane channel in epidermal keratinocytes, facilitates water and glycerol movement into and out of the skin. Here, we demonstrate that AQP3 is also expressed in cultured human skin fibroblasts, which under normal wound healing processes migrate from surrounding tissues to close the wound. EGF (epidermal growth factor), which induced fibroblast migration, also induced AQP3 expression in a time- and dose-dependent manner. CuSO4 and NiCl2, previously known as AQP3 water transport inhibitors, as well as two other bivalent heavy metals Mn2+ and Co2+, inhibited EGF-induced cell migration in human skin fibroblasts. AQP3 knockdown by small interfering RNA inhibited EGF-induced AQP3 expression and cell migration. Furthermore, an EGFR (EGF receptor) kinase inhibitor, PD153035, blocked EGF-induced AQP3 expression and cell migration. MEK [MAPK (mitogen-activated protein kinase)/ERK (extracellular-signal-regulated kinase) kinase]/ERK inhibitor U0126 and PI3K (phosphoinositide 3-kinase) inhibitor LY294002 also inhibited EGF-induced AQP3 expression and cell migration. Collectively, our findings show for the first time that AQP3 is expressed in human skin fibroblasts and that EGF induces AQP3 expression via EGFR, PI3K and ERK signal transduction pathways. We have provided evidence for a novel role of AQP3 in human skin fibroblast cell migration, which occurs during normal wound healing.

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EGFR-mediated expression of aquaporin-3 is involved in human skin fibroblast migration

Increased microRNA-146a/b, TRAF6 gene and decreased IRAK1 gene expressions in the peripheral mononuclear cells of patients with Sjögren's syndrome.

Background: Thymosin α1 (Tα1), a synthetic version of a thymic-derived biological response modifier was the first of the thymosins in clinical use. Tα1 is approved in over 35 countries for the treatment of hepatitis B and C, and as an immune stimulant and adjuvant. Tα1 is also in late-stage clinical testing in the United States and Europe for hepatitis C and stage IV melanoma. Objective/methods: Novel applications and other recently completed trials point to much broader clinical applications of Tα1 in the treatment of life-threatening and chronic diseases, and are the subject of this review. Result/conclusions: The most recent reports of clinical trials with Tα1 are pointing to important, hitherto unrecognized, applications in a number of diseases and disorders, including septic shock, acute respiratory distress syndrome, peritonitis, acute cytomegalovirus infection, TB, severe acute respiratory syndrome, and lung infections in critically ill patients. It is also emerging as a promising chemoprotection a...

From lab to bedside: emerging clinical applications of thymosin alpha 1.

Background
Inflammation is a highly complex biological response evoked by many stimuli. A persistent challenge in modeling this dynamic process has been the (nonlinear) nature of the response that precludes the single-variable assumption. Systems-based approaches offer a promising possibility for understanding inflammation in its homeostatic context. In order to study the underlying complexity of the acute inflammatory response, an agent-based framework is developed that models the emerging host response as the outcome of orchestrated interactions associated with intricate signaling cascades and intercellular immune system interactions.

/pdf/agent-based-modeling-of-endotoxin-induced-acute-inflammatory-57h6k9frvy.pdf

Agent-based modeling of endotoxin-induced acute inflammatory response in human blood leukocytes.

Thymosin α1 (Tα1) is noted for its immunomodulatory activities and therapeutic potential in treatment of infectious diseases and cancer. However, the molecular mechanism of its effectiveness is not completely understood. Here, we report that Tα1 induces interleukin (IL)-6 expression through the IκB kinase (IKK) and nuclear factor-κB (NF-κB) pathway. Using IKKβ-deficient bone-marrow-derived macrophages and mouse embryo fibroblasts (MEFs), we show that IKKβ is essential for IKK and NF-κB activation as well as efficient IL-6 induction. Further analysis using tumour necrosis factor receptor-associated factor 6 (TRAF6)-deficient MEFs shows that TRAF6 is crucial for activation of IKK and induction of IL-6 by Tα1. Intriguingly, Tα1 triggers protein kinase C (PKC)ι/ζ activation, which is TRAF6 dependent and involves IKK. In addition, Tα1 induces the formation of a signalsome composed of TRAF6, p62 and PKCι/ζ as well as IKK. Thus, our study identifies Tα1 as a unique activator of the TRAF6 signal pathway and provides a cohesive interpretation of the molecular basis of the therapeutic utility of Tα1.

/pdf/activation-of-ikk-by-thymosin-a1-requires-the-traf6-1pnd6fb7nf.pdf

Activation of IKK by thymosin α1 requires the TRAF6 signalling pathway

Thymosin alpha 1 (Talpha1) has therapeutic potential in the treatment of infectious diseases and cancer. However, the exact molecular pathways for Talpha1 action are not fully understood. We found that Talpha1 induces the production of interleukin-6 (IL-6), IL-10, and IL-12 in murine bone marrow-derived macrophages (BMDMs) through IKK and MAPK pathways. Talpha1 triggers the activation of AP-1 and the phosphorylation of JNK and p38. Inhibition of p38 impairs IL-6 production in response to Talpha1. Further, TRAF6 is involved in the activation of JNK and IRAK4 is involved for the activation of IKK and PKCzeta in a Talpha1-induced system. Loss of IRAK4 largely blocked induction of IL-6. Thus, our studies define early signal events that are critical for the Talpha1-induced immune responses.

Justin Chan

Papers

Activation of IKK by thymosin α1 requires the TRAF6 signalling pathway

Signaling Pathways Leading to the Activation of IKK and MAPK by Thymosin α1