Sunday, May 22, 2011

Cis-elements as Maf-Maf homodimers/Maf-Nrf2 heterodimers and its negative regulators like p45 NF-E2 in the Nrf2/Keap1 system.

 Structure of the Keap1:Nrf2 interface.
 The Nrf2 peptide contains two short antiparallel beta-strands connected by two overlapping type I beta-turns stabilized by the aspartate and threonine residues.  
Structure of the Keap1:Nrf2 interface
Transcript Variant: NRF1. This variant (1) represents the longest transcript and encodes the longest isoform PDB Structure: 2FLU
NRF2 is the primary regulator of this endogenous antioxidant response, (nuclear factor erythroid 2-related factor 2) is located on 2q31: [§§] encoding NFE2 (an essential regulator of megakaryopoiesis), NFE2L1, and NFE2L2 basic-leucine zipper (bZIP) transcription factors, which play roles in oxidative and the e.g. (StRE/ARE) presumed natural antioxidants sulforaphane (SFN) and curcumin  xenobiotic (XRE) stresses may be therapeutic for cholestasis preventing carcinogenesis. However, the molecular mechanism of this regulation remains resolved in the six-bladed beta propeller crystal structure of the Kelch domains, the Cap-N-Collar (CNC) transcription factor family (BACH1) and its negative regulators like p45 NF-E2 in the Nrf2/Keap1 system. Nrf2 activation is mainly cytoprotective.  Nuclear accumulation of erythroid derived 2, like (Nrf2) increase the expression of the antioxidant HMOX1, and the expression of stress-responsive genes responsible for reactive oxygen species, (ROS) promote megakaryopoiesis elimination during maturation where HIF-1 is primarily induced in  the hypoxic and unstable oxygenation microenvironment of a tumor in several human cancers. Nrf2 dominant-negative mutant with the NQO1/NQO2 gene nuclear proteins a prototypical Nrf2 target cytosolic protein gene that catalyzes the metabolic reduction of quinones bind to the six putative ARE (antioxidant response cis-elements) as Maf-Maf homodimers (the term "Maf" is derived from MusculoAponeurotic-Fibrosarcoma virus) and Maf-Nrf2 heterodimers hMaf heterodimerizes specifically with Nrf1 and Nrf2, human BSEP (bile salt export pump) and the conjugate efflux pump (dietary chemopreventive agent sulforaphane (SFN) similar oxidized low-density lipoprotein is attributed to toxicity by siRNA-Nrf2)  reveals two similar musculo-aponeurotic fibrosacroma (Maf) recognition elements (MAREs). Nrf2 is released from Keap1, and translocates to the nucleus, Keap1 (Kelch-like ECH-associated protein 1) is the major upstream regulator of Nrf1, a BTB-Kelch substrate adaptor protein, through cis-active sequences (TXAS gene utilizes the same cis-acting element) known as antioxidant response element ARE is controlled by the NES nuclear export function Keap1 counteracts, that translocates in the nucleus once, in the cytoplasm ubiquitination targets Nrf2 for degradation (CRIF1, unlike KEAP1, both N- and C-terminal regions), and hence typifying oxidative stress-mediated apoptosis that lead to alteration of the Keap1-Cul3 [cullin 3] interaction (cytosolic and mitochondrial glutathione (GSTs) and protein-thiol redox imbalance), can no longer serve to target Nrf2 for ubiquitination, though it retains its affinity for Nrf2. The INrf2 (Keap1)/Cul3-Rbx1 [ring-box 1, E3 ubiquitin protein ligase] complex constantly degrades Nrf2 under normal conditions. ENC1-mediated  (ectodermal-neural cortex 1) down-regulation of Nrf2 was independent of Keap1, ENC1 is a BTB-Kelch protein and belongs to the same family as Keap1. Whereby Nrf2 activity is beneficial in non-malignant cells in  human neuroblastoma cells it may provide a advantage in ECs, containing several Nrf2 target genes (NQO1 and HO-1), induces MRP1 (Multidrug-resistant proteins) upregulation, leading to overexpressed its target Trx-1 [Thioredoxin] such as in human breast cancer cells for their survival against chemotherapeutic agents one of the at least two trans-acting transcription factors Polyamine-modulated factor 1 (PMF-1) binds to NF-E2 related factor-2f  that, Spermidine/spermine N(1)-acetyltransferase SSAT is regulated by.

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