The heterogeneous nuclear ribonucleoprotein (hnRNP) K protein recruits a diversity of molecular partners that are involved in signal transduction, transcription, RNA processing, and translation. K protein is phosphorylated in vivo and in vitro by inducible kinase(s) and contains several potential sites for protein kinase C (PKC) phosphorylation. In this study we show that K protein is phosphorylated in vitro by PKC␦ and by other PKCs. Deletion analysis and site-directed mutagenesis revealed that Ser 302 is a major K protein site phosphorylated by PKC␦ in vitro. This residue is located in the middle of a short amino acid fragment that divides the two clusters of SH3-binding domains. Mutation of Ser 302 decreased the level of phosphorylation of exogenously expressed K protein in phorbol 12-myristate 13-acetate-treated COS cells, suggesting that Ser 302 is also a site for PKC-mediated phosphorylation in vivo. In vitro, PKC␦ binds K protein via the highly interactive KI domain, an interaction that is blocked by poly(C) RNA. Mutation of Ser 302 did not alter the K protein-PKC␦ interaction in vitro, suggesting that phosphorylation of this residue alone is not sufficient to alter this interaction. Instead, binding of PKC␦ to K protein in vitro and in vivo was greatly increased by K protein phosphorylation on tyrosine residues. The ability of PKC␦ to bind and phosphorylate K protein may serve not only to alter the activity of K protein itself, but K protein may also bridge PKC␦ to other K protein molecular partners and thus facilitate molecular cross-talk. The regulated nature of the PKC␦-K protein interaction may serve to meet cellular needs at sites of active transcription, RNA processing and translation in response to changing extracellular environment.

The heterogeneous nuclear ribonucleoprotein K protein recruits a diversity of molecular partners and may act as a docking platform involved in such processes as transcription, RNA processing, and translation. We show that K protein is tyrosine-phosphorylated in vitro by Src and Lck. Treatment with H 2 O 2 /Na 3 VO 4 , which induces oxidative stress, stimulated tyrosine phosphorylation of K protein in cultured cells and in intact livers. Tyrosine phosphorylation increased binding of Lck and the proto-oncoprotein Vav to K protein in vitro. Oxidative stress increased the association of K protein with Lck and Vav, suggesting that tyrosine phosphorylation regulates the ability of K protein to recruit these effectors in vivo. Translation-based assay showed that K protein is constitutively bound to many mRNAs in vivo. Native immunoprecipitated K protein-mRNA complexes were disrupted by tyrosine phosphorylation, suggesting that the in vivo binding of K protein to mRNA may be responsive to the extracellular signals that activate tyrosine kinases. This study shows that tyrosine phosphorylation of K protein regulates K protein-protein and K protein-RNA interactions. These data are consistent with a model in which functional interaction of K protein is responsive to changes in the extracellular environment. Acting as a docking platform, K protein may bridge signal transduction pathways to sites of nucleic acid-dependent process such as transcription, RNA processing, and translation.The heterogeneous nuclear ribonucleoprotein (hnRNP) 1 K protein is a highly interactive factor (1, 2) that appears to act at multiple tiers of gene expression including transcription (3-5), translation (6, 7), and probably RNA processing (2, 8).K protein is composed of multiple domains that serve to engage a diverse group of molecular partners (1) including DNA (5, 9), RNA (10 -13), Vav (14, 15), transcriptional repressors (16, 17), and inducible kinases (14, 18 -22). While the interaction of K protein with the transcription factor CCAAT/ enhancer-binding protein ␤ is mediated by the N-terminal third of K protein (4), K protein interaction with an interleukin-1-responsive kinase is mediated by the C-terminal domain (14). The interaction of K protein with the Src family of tyrosine kinases (14), PKC␦ (21), Vav (14), and several transcriptional repressors (16, 17) is mediated by the centrally located prolinerich KI domain. It is interesting to note that TATA box-binding protein (5) binds adjacent to the KI domain. 2 K protein's modular structure and its highly interactive nature suggest that K protein acts as a docking platform or scaffold (1). The observations that K protein also interacts with RNA and DNA suggest that K protein may do so at sites of nucleic acid-dependent processes.K protein is phosphorylated in vivo in response to treatment of cells with cytokines, acute phase reactants, and other changes in the extracellular environment (21-23) indicating that K protein is coupled to signal transduction. Taken together, the biochemical and func...

Key Points• Adoptive transfer of autologous lentiviral-engineered T cells expressing an antisense is safe in chronic HIV infection.• Conditionally replicating lentiviral vector was associated with antiviral effects in patients as assessed by viral evolution and viral load.

In this setting, peptide-loaded DC vaccination elicits modest immune responses, but survival is promising. Pneumococcal vaccination revealed substantial immune suppression, even in patients in remission. Rational design of consolidative strategies for ovarian cancer will need to overcome tolerance and immunosuppression.

The interaction of the multimodular heterogeneous nuclear ribonucleoprotein (hnRNP) K protein with many of its protein and nucleic acid partners is regulated by extracellular signals. Acting as a docking platform, K protein could link signal-transduction pathways to DNA- and RNA-directed processes such as transcription, mRNA processing, transport, and translation. Treatment of hepatocyte culture with insulin increased K protein tyrosine phosphorylation. Insulin altered K protein interaction with RNA and DNA in vitro. Administration of insulin into mice had similar effects on K protein in liver. Coimmunoprecipitations of RNA with K protein revealed preferential in vivo K protein binding of a subset of transcripts, including the insulin-inducible c-fos mRNA. These results suggest a class of insulin pathways that signal nucleic acid-directed processes that involve K protein