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Author(s): Marcello Ceci [1, 2]; Cristina Gaviraghi [1, 2]; Chiara Gorrini [1, 2]; Leonardo A. Sala [1, 2]; Nina Offenhäuser [3]; Pier Carlo Marchisio [1, 2]; Stefano Biffo (corresponding author) [...]

During avian embryonic development, terminal erythroid differentiation occurs in the circulation. Some of the key events, such as the induction of erythroid 2,3-bisphosphoglycerate (2,3-BPG), carbonic anhydrase (CAII), and pyrimidine 5'-nucleotidase (P5N) synthesis are oxygen dependent (Baumann R, Haller EA, Schoning U, and Weber M, Dev Biol 116: 548-551, 1986; Dragon S and Baumann R, Am J Physiol Regulatory Integrative Comp Physiol 280: R870-R878, 2001; Dragon S, Carey C, Martin K, and Baumann R, J Exp Biol 202: 2787-2795, 1999; Dragon S, Glombitza S, Gotz R, and Baumann R, Am J Physiol Regulatory Integrative Comp Physiol 271: R982-R989, 1996; Dragon S, Hille R, Gotz R, and Baumann R, Blood 91: 3052-3058, 1998; Million D, Zillner P, and Baumann R, Am J Physiol Regulatory Integrative Comp Physiol 261: R1188-R1196, 1991) in an indirect way: hypoxia stimulates the release of norepinephrine (NE)/adenosine into the circulation (Dragon et al., J Exp Biol 202: 2787-2795, 1999; Dragon et al., Am J Physiol Regulatory Integrative Comp Physiol 271: R982-R989, 1996). This leads via erythroid [beta]-adrenergic/adenosine [A.sub.2] receptor activation to a cAMP signal inducing several proteins in a transcription-dependent manner (Dragon et al., Am J Physiol Regulatory Integrative Comp Physiol 271: R982-R989, 1996; Dragon et al., Blood 91: 3052-3058, 1998; Glombitza S, Dragon S, Berghammer M, Pannermayr M, and Baumann R, Am J Physiol Regulatory Integrative Comp Physiol 271: R973-R981, 1996). To understand how the cAMP-dependent processes are initiated, we screened an erythroid cDNA library for cAMP-regulated genes. We detected three genes that were strongly upregulated (>5-fold) by cAMP in definitive and primitive red blood cells. They are homologous to the mammalian Tob, Ifr1, and Fos proteins. In addition, the genes are induced in the intact embryo during short-term hypoxia. Because the genes are regulators of proliferation and differentiation in other cell types, we suggest that cAMP might promote general differentiating processes in erythroid cells, thereby allowing adaptive modulation of the latest steps of erythroid differentiation during developmental hypoxia. erythropoiesis; terminal differentiation; adaptation; gene expression

Nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT-3) selectively bind to distinct members of the Trk family of tyrosine kinase receptors, but all three bind with similar affinities to the neurotrophin receptor p75 ([p75.sup.NTR]). The biological significance of neurotrophin binding to [p75.sup.NTR] in cells that also express Trk receptors has been difficult to ascertain. In the absence of TrkA, NGF binding to [p75.sup.NTR] activated the transcription factor nuclear factor kappa B (NF-kB) in rat Schwann cells. This activation was not observed in Schwann cells isolated from mice that lacked [p75.sup.NTR]. The effect was selective for NGF; NF-kB was not activated by BDNF or NT-3., The best established role for neurotrophins, which include NGF, BDNF, NT-3, NT-4/5, and NT-6, is their ability to support the survival and differentiation of neurons. Three tyrosine kinase receptors, referred [...]

The evidence for mechanisms linking actin dynamics to behavioral responses to ethanol is provided from study report about Eps8, which regulates acute ethanol sensitivity and ethanol consumption in mice. From the result it is concluded that Eps8 is required in the N-methyl-D-aspartate receptor-signaling pathway leading to activation of cofilin and actin-filament turnover.