Constitutive NF-kappa B activation, enhanced granulopoiesis, and neonatal lethality in I kappa B alpha-deficient mice.

Transcription factors belonging to the NF-kappa B family are controlled by inhibitory I kappa B proteins, mainly I kappa B alpha and I kappa B beta. Apparently normal at birth, I kappa B alpha-/- mice exhibit severe runting, skin defects, and extensive granulopoiesis postnatally, typically dying by 8 days. Hematopoietic tissues from these mice display elevated levels of both nuclear NF-kappa B and mRNAs of some, but not all, genes thought to be regulated by NF-kappa B.

HIV-1 messenger RNA in peripheral blood mononuclear cells as an early marker of risk for progression to AIDS.

Objective: To establish human immunodeficiency virus type 1 (HIV-1) messenger RNA (mRNA) expression in peripheral blood mononuclear cells as a marker of risk for progression to the acquired immunodeficiency syndrome (AIDS) in a large cohort of HIV-infected persons followed for a prolonged period.

Design: Retrospective testing of cryopreserved, coded specimens.

Setting: Research laboratories at the New York Blood Center and the Rockefeller University.

Tissue-regulated differentiation and maturation of a v-abl-immortalized mast cell-committed progenitor.

An immature v-abl-transformed mast cell line (V3-MC) was derived from a mouse that developed systemic mastocytosis after transplantation of v-abl-infected bone marrow cells. V3-MCs injected intravenously into adult BALB/c mice infiltrated the liver, spleen, and intestine by day 6 and underwent progressive differentiation and maturation, eventually resembling indigenous mast cells. In terms of their protease content, the V3-MCs that localized in the liver and spleen differed from those in the intestine, and both differed from the cultured V3-MCs.

Embryonic lethality and liver degeneration in mice lacking the RelA component of NF-kappa B.

NF-kappa B, which consists of two polypeptides, p50 (M(r) 50K) and p65/RelA (M(r) 65K), is thought to be a key regulator of genes involved in responses to infection, inflammation and stress. Indeed, although developmentally normal, mice deficient in p50 display functional defects in immune responses. Here we describe the generation of mice deficient in the RelA subunit of NF-kappa B.

3BP-1, an SH3 domain binding protein, has GAP activity for Rac and inhibits growth factor-induced membrane ruffling in fibroblasts.

The SH3 binding protein, 3BP-1, was originally cloned as a partial cDNA from an expression library using the Abl SH3 domain as a probe. In addition to an SH3 binding domain, 3BP-1 displayed homology to a class of GTPase activating proteins (GAPs) active against Rac and Rho proteins. We report here a full length cDNA of 3BP-1 which extends the homology to GAP proteins previously noted.

Proline-rich sequences that bind to Src homology 3 domains with individual specificities.

To study the binding specificity of Src homology 3 (SH3) domains, we have screened a mouse embryonic expression library for peptide fragments that interact with them. Several clones were identified that express fragments of proteins which, through proline-rich binding sites, exhibit differential binding specificity to various SH3 domains. Src-SH3-specific binding uses a sequence of 7 aa of the consensus RPLPXXP, in which the N-terminal arginine is very important.

Involvement of CRAF1, a relative of TRAF, in CD40 signaling.

CD40 is a receptor on the surface of B lymphocytes, the activation of which leads to B cell survival, growth, and differentiation. A yeast two-hybrid screen identified a gene, CRAF1, encoding a protein that interacts directly with the CD40 cytoplasmic tail through a region of similarity to the tumor necrosis factor-alpha (TNF-alpha) receptor-associated factors. Overexpression of a truncated CRAF1 gene inhibited CD40-mediated up-regulation of CD23.

Reduction of caveolin and caveolae in oncogenically transformed cells.

Caveolae are flask-shaped non-clathrin-coated invaginations of the plasma membrane. In addition to the demonstrated roles for caveolae in potocytosis and transcytosis, caveolae may regulate the transduction of signals from the plasma membrane. Transformation of NIH 3T3 cells by various oncogenes leads to reductions in cellular levels of caveolin, a principal component of the protein coat of caveolae.

Proline-rich (PxxP) motifs in HIV-1 Nef bind to SH3 domains of a subset of Src kinases and are required for the enhanced growth of Nef+ viruses but not for down-regulation of CD4.

Human immunodeficiency virus (HIV) and simian immunodeficiency virus Nef proteins contain a conserved motif with the minimal consensus (PxxP) site for Src homology region 3 (SH3)-mediated protein-protein interactions. Nef PxxP motifs show specific binding to biotinylated SH3 domains of Hck and Lyn, but not to those of other tested Src family kinases or less related proteins. A unique cooperative role of a distant proline is also observed.

Targeted disruption of the p50 subunit of NF-kappa B leads to multifocal defects in immune responses.

NF-kappa B, a heterodimeric transcription factor composed of p50 and p65 subunits, can be activated in many cell types and is thought to regulate a wide variety of genes involved in immune function and development. Mice lacking the p50 subunit of NF-kappa B show no developmental abnormalities, but exhibit multifocal defects in immune responses involving B lymphocytes and nonspecific responses to infection. B cells do not proliferate in response to bacterial lipopolysaccharide and are defective in basal and specific antibody production.

Binding of Vav to Grb2 through dimerization of Src homology 3 domains.

The protooncogenic protein Vav has the structure of an intracellular signal transducer. It is exclusively expressed in cells of hematopoietic lineage and plays a crucial role in hematopoietic cell differentiation. Here we report that both in cell extracts and within intact mammalian cells Vav binds to Grb2 (Sem-5/ASH/Drk), an adaptor molecule which plays a key role in Ras activation.

SH2 and SH3 domains as molecular adhesives: the interactions of Crk and Abl.

The Src homology domains SH2 and SH3 are modular components present in many signal transduction proteins. They allow rapid formation of stable protein complexes and may also regulate protein function through intramolecular binding events. SH2 domains recognize phosphotyrosyl residues in a specific sequence context, while SH3 domains recognize a PxxP motif and additional residues that mediate binding specificity.

Engineering poliovirus as a vaccine vector for the expression of diverse antigens.

As a step toward developing poliovirus as a vaccine vector, poliovirus recombinants were constructed by fusing exogenous peptides (up to 400 amino acids) and an artificial cleavage site for viral protease 3Cpro to the amino terminus of the viral polyprotein. Viral replication proceeded normally. An extended polyprotein was produced in infected cells and proteolytically processed into the complete array of viral proteins plus the foreign peptide, which was excluded from mature virions.

Binding of Bruton's tyrosine kinase to Fyn, Lyn, or Hck through a Src homology 3 domain-mediated interaction.

Bruton's tyrosine kinase (Btk) is a recently described B-cell-specific tyrosine kinase. Mutations in this gene lead to human X chromosome-linked agammaglobulinemia and murine X-linked immunodeficiency. Although genetic evidence strongly suggests that Btk plays a crucial role in B-lymphocyte differentiation and activation, its precise mechanism of action remains unknown, primarily because the proteins that it interacts with have not yet been identified.

RAG-1 interacts with the repeated amino acid motif of the human homologue of the yeast protein SRP1.

Genes for immunoglobulins and T-cell receptor are generated by a process known as V(D)J recombination. This process is highly regulated and mediated by the recombination activating proteins RAG-1 and RAG-2. By the use of the two-hybrid protein interaction system, we isolated a human protein that specifically interacts with RAG-1.

Sequential induction of NF-kappa B/Rel family proteins during B-cell terminal differentiation.

The NF-kappa B/Rel family of at least five transcription factor polypeptides is thought to function both as a developmental regulator in B cells and as a rapid response system in all cells. To examine this notion in more detail, we determined the protein contents of both the inducible and constitutive NF-kappa B/Rel activities in a pre-B-cell line, 70Z/3, and a mature B-cell line, WEHI 231. NF-kappa B p50/p65 is the major inducible nuclear complex after lipopolysaccharide or phorbol myristate acetate treatment of 70Z/3 cells.