Notch1 Augments NF- ĸB Activity by Facilitating its Nuclear Retention

Notch1 specifically upregulates expression of the cytokine interferon-gamma in peripheral T cells through activation of NF-kappaB. However, how Notch mediates NF-kappaB activation remains unclear. Here, we examined the temporal relationship between Notch signaling and NF-kappaB induction during T-cell activation. NF-kappaB activation occurs within minutes of T-cell receptor (TCR) engagement and this activation is sustained for at least 48 h following TCR signaling. We used gamma-secretase inhibitor (GSI) to prevent the cleavage and subsequent activation of Notch family members. We demonstrate that GSI blocked the later, sustained NF-kappaB activation, but did not affect the initial activation of NF-kappaB. Using biochemical approaches, as well as confocal microscopy, we show that the intracellular domain of Notch1 (N1IC) directly interacts with NF-kappaB and competes with IkappaBalpha, leading to retention of NF-kappaB in the nucleus. Additionally, we show that N1IC can directly regulate IFN-gamma expression through complexes formed on the IFN-gamma promoter. Taken together, these data suggest that there are two \u27waves\u27 of NF-kappaB activation: an initial, Notch-independent phase, and a later, sustained activation of NF-kappaB, which is Notch dependent

Hereditary dysautonomias: current knowledge and collaborations for the future

The hereditary dysautonomias (H-Dys) are a large group of disorders that affect the autonomic nervous system. Research in the field of H-Dys is very challenging, because the disorders involve interdisciplinary, integrative, and "mind-body" connections. Recently, medical scientists, NIH/NINDS representatives, and several patient support groups gathered for the first time in order to discuss recent findings and future directions in the H-Dys field. The H-Dys workshop was instrumental in promoting interactions between basic science and clinical investigators. It also allowed attendees to have an opportunity to meet each other, understand the similarities between the various forms of dysautonomia, and experience the unique perspective offered by patients and their families. Future advances in H-Dys research will depend on a novel multi-system approach by investigators from different medical disciplines, and it is hoped that towards a common goal, novel "bench-to-bedside" therapeutics will be developed to improve the lives of, or even cure, patients suffering from dysautonomic syndromes

Regulation of IκBβ Expression in Testis

IκBα and IκBβ are regulators of the nuclear factor-κB (NF-κB) transcription factor family. Both IκBs bind to the same NF-κB dimers and are widely expressed in different cells and tissues. To better understand how these two IκB isoforms differ biologically, we have characterized the expression of IκBβ in testis, a tissue in which IκBα is only minimally expressed. We have found that IκBβ expression is localized within the haploid spermatid stages of spermatogenesis and follows the expression of nuclear NF-κB. IκBβ expression in haploid spermatids is likely regulated by Sox family proteins, members of which are also expressed within spermatids. We have shown that both SRY and Sox-5 can bind to multiple Sox binding sites found within the IκBβ promoter and can enhance transcription of a reporter gene in transient transfection assays. We also demonstrate that IκBβ mRNA is strongly expressed in developing male gonads. These results therefore suggest that IκBβ may be a novel target for transcription factors of the HMG-box SRY/Sox family and imply a potential role for NF-κB/IκBβ in spermatogenesis