Regulation of TNFa signaling

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DESCRIPTION (provided by applicant): The long-term goal of our research is to investigate how the intracellular signaling circuitry is wired in response to specific extracellular stimuli, thereby identifying potential therapeutic targets for prevention and treatment of human diseases. In this proposal, we will study the molecular mechanism by which the zinc finger protein Miz1, a novel signal- and pathway- specific modulators or regulators (SMOR) in the JNK signalsome, selectively regulates TNFalpha-induced JNK activation and the pathophysiological implications of this regulation. Using multifaceted approaches, we have recently discovered that Miz1 acts as a novel signal- and pathway-specific modulators or regulators (SMOR) to negatively regulate TNFalpha- induced JNK activation. Miz1 suppresses TNFalpha-induced K63-linked polyubiquitination of TRAF2, thereby only inhibiting activation of JNK but not ERK, p38 or IKK by TNFalpha, and only JNK activation by TNFalpha but not IL-1, UV, TPA, or other JNK activators. Upon TNFalpha stimulation, Miz1 undergoes ubiquitination and subsequent proteasomal degradation, thereby relieving its inhibition. We hypothesize that Miz1 is a novel component of TNF-R1 Complex 1 and plays a critical role in regulation of TNFalpha signaling. This proposal is novel, as it will study how Miz1 functions as a novel component of TNF-R1 Complex 1, to study whether Miz1 determines the kinetic difference between TNFalpha- activated JNK and IKK, and to determine the pathophysiological functions of Miz1-mediated inhibition on the TNFalpha signlaing in vivo. This study will put forward a novel paradigm regarding the molecular mechanism by which activation of TNF-R1 Complex is regulated and will provide a better understanding of the molecular basis underlying regulation of TNF-alpha signaling, which is important in inflammation in many human diseases. PUBLIC HEALTH RELEVANCE: The pro-inflammatory cytokine tumor necrosis factor (TNFa) regulates immune responses, inflammation, and programmed cell death through activation of its downstream effectors such as NF-kB, JNK and caspases. Understanding how selective regulation of TNFa signaling by Miz1 should shed light on our understanding of molecular mechanism underlying activation of TNF1 receptor complex, which deregulation leads to human diseases.