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NIPP1 (nuclear inhibitor of protein phosphatase 1) is a ubiquitously expressed nuclear scaffold protein that has been implicated in both transcription and RNA processing. Among its protein ligands are a protein kinase, a protein phosphatase, two splicing factors, and a transcriptional regulator, and the binding of these proteins to NIPP1 is tightly regulated by phosphorylation. To study the function of NIPP1 in vivo, we have used homologous recombination to generate mice that are deficient in NIPP1. NIPP1-/+ mice developed normally. However, NIPP1-/- embryos showed severely retarded growth at embryonic day 6.5 (E6.5) and were resorbed by E8.5. This early embryonic lethality was not associated with increased apoptosis but correlated with impaired cell proliferation. Blastocyst outgrowth experiments and the RNA interference-mediated knockdown of NIPP1 in cultured cells also revealed an essential role for NIPP1 in cell proliferation. In further agreement with this function, no viable NIPP1-/- cell lines were obtained by derivation of embryonic stem (ES) cells from blastocysts of NIPP1-/+ intercrosses or by forced homogenotization of heterozygous ES cells at high concentrations of Geneticin. We conclude that NIPP1 is indispensable for early embryonic development and cell proliferation. [ABSTRACT FROM AUTHOR]

Dendritic cell (DC)-based immunotherapy has yielded promising results against high-grade glioma (HGG). However, the efficacy of DC vaccines is abated by HGG-induced immunosuppression and lack of attention toward the immunogenicity of the tumor lysate/cells used for pulsing DCs. A literature analysis of DC vaccination clinical trials in HGG patients delineated the following two most predominantly applied methods for tumor lysate preparation: freeze-thaw (FT)-induced necrosis or FT-necrosis followed by X-ray irradiation. However, from the available clinical evidence, it is unclear which of both methodologies has superior immunogenic potential. Using an orthotopic HGG murine model (GL261-C57BL/6), we observed that prophylactic vaccination with DCs pulsed with irradiated FT-necrotic cells (compared to FT-necrotic cells only) prolonged overall survival by increasing tumor rejection in glioma-challenged mice. This was associated, both in prophylactic and curative vaccination setups, with an increase in brain-infiltrating Th1 cells and cytotoxic T lymphocytes (CTL), paralleled by a reduced accumulation of regulatory T cells, tumor-associated macrophages (TAM) and myeloid-derived suppressor cells (MDSC). Further analysis showed that irradiation treatment of FT-necrotic cells considerably increased the levels of carbonylated proteins — a surrogate-marker of oxidation-associated molecular patterns (OAMPs). Through further application of antioxidants and hydrogen peroxide, we found a striking correlation between the amount of lysate-associated protein carbonylation/OAMPs and DC vaccine-mediated tumor rejection capacity thereby suggesting for the first time a role for protein carbonylation/OAMPs in at least partially mediating antitumor immunity. Together, these data strongly advocate the use of protein oxidation-inducing modalities like irradiation for increasing the immunogenicity of tumor lysate/cells used for pulsing DC vaccines. [ABSTRACT FROM AUTHOR]