Sheep Anti-Human Nfkb P65 Polyclonal antibody

The classical NF-kappa B transcription factor (RelA:p50) and the tumor suppressor Sef axis constitute a negative regulatory loop in which Sef, a target of NF-kappa B/RelA:p50, fine-tunes NF-kappa B/RelA:p50 transcriptional-activation in response to inflammatory stimuli trough binding to p50. Similar to the inhibitor I kappa B alpha, Sef sequesters NF-kappa B/RelA:p50 in the cytoplasm of unstimulated cells. Despite its key roles in regulating multiple cellular processes and its potential role as mediator between inflammation and cancer, Sef structural domains required to fulfill its tasks are poorly characterized, and how Sef specificity towards RelA:p50 is achieved is unknown. In-vitro binding assays using bacterially expressed Sef and Co-IP experiments, revealed that in addition to p50, Sef directly interacts with I kappa B alpha, and the IKK beta subunit of the IKK complex which mediates RelA:p50 induction by inflammatory stimuli. These interactions are ligand-independent and do not require Sef post-translational modifications. Deletion mutagenesis mapped binding site to IKK beta in a 74- residue segment juxtaposing Sef trans membrane domain, whereas several Sef regions seem to interact with I kappa B alpha. Moreover, we identified two new sites which together with the previously identified conserved tyrosine constitute three discontinuous Sef regions each indispensable for Sef binding to RelA:p50 and inhibiting its cytokine induced transcriptional activation. Contrary to I kappa B alpha, endogenous Sef is not degraded upon cytokine-stimulation, and its targeting in different cell types markedly enhances cytokine-induced NF-kappa B nuclear translocation. These results reveal Sef as the first scaffold that brings together the components of NF-kappa B/RelA:p50 signaling-module. Sef scaffolding function explains the basis for Sef specificity towards inhibiting inflammatory cytokine-induction of NF-kappa B/RelA:p50.

Antibiotic failure not only is due to the development of resistance by pathogens but can also often be explained by persistence and tolerance. Persistence and tolerance can be included in the "persistent phenotype," with high relevance for clinics. Two of the most important molecular mechanisms involved in tolerance and persistence are toxin-antitoxin (TA) modules and signaling via guanosine pentaphosphate/tetraphosphate [(p)ppGpp], also known as "magic spot." (p)ppGpp is a very important stress alarmone which orchestrates the stringent response in bacteria; hence, (p)ppGpp is produced during amino acid or fatty acid starvation by proteins belonging to the RelA/SpoT homolog family (RSH). However, (p)ppGpp levels can also accumulate in response to a wide range of signals, including oxygen variation, pH downshift, osmotic shock, temperature shift, or even exposure to darkness. Furthermore, the stringent response is not only involved in responses to environmental stresses (starvation for carbon sources, fatty acids, and phosphates or heat shock), but it is also used in bacterial pathogenesis, host invasion, and antibiotic tolerance and persistence. Given the exhaustive and contradictory literature surrounding the role of (p)ppGpp in bacterial persistence, and with the aim of summarizing what is known so far about the magic spot in this bacterial stage, this review provides new insights into the link between the stringent response and persistence. Moreover, we review some of the innovative treatments that have (p)ppGpp as a target, which are in the spotlight of the scientific community as candidates for effective antipersistence agents.