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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on BaF3 by Materials Project

BaF3 is alpha bismuth trifluoride structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ba is bonded to twelve F atoms to form a mixture of corner, edge, and face-sharing BaF12 cuboctahedra. There are eight shorter (2.78 Å) and four longer (2.99 Å) Ba–F bond lengths. There are two inequivalent F sites. In the first F site, F is bonded to four equivalent Ba atoms to form a mixture of corner and edge-sharing FBa4 tetrahedra. In the second F site, F is bonded in a square co-planar geometry to four equivalent Ba atoms.

36 MATERIALS SCIENCE↗
NASA NTRS2001

Erythropoietin activates two distinct signaling pathways required for the initiation and the elongation of c-myc

Erythropoietin (Epo) stimulation of erythroid cells results in the activation of several kinases and a rapid induction of c-myc expression. Protein kinase C is necessary for Epo up-regulation of c-myc by promoting elongation at the 3'-end of exon 1. PKCepsilon mediates this signal. We now show that Epo triggers two signaling pathways to c-myc. Epo rapidly up-regulated Myc protein in BaF3-EpoR cells. The phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 blocked Myc up-regulation in a concentration-dependent manner but had no effect on the Epo-induced phosphorylation of ERK1 and ERK2. LY294002 also had no effect on Epo up-regulation of c-fos. MEK1 inhibitor PD98059 blocked both the c-myc and the c-fos responses to Epo. PD98059 and the PKC inhibitor H7 also blocked the phosphorylation of ERK1 and ERK2. PD98059 but not LY294002 inhibited Epo induction of ERK1 and ERK2 phosphorylation in normal erythroid cells. LY294002 blocked transcription of c-myc at exon 1. PD98059 had no effect on transcription from exon 1 but, rather, blocked Epo-induced c-myc elongation at the 3'-end of exon 1. These results identify two Epo signaling pathways to c-myc, one of which is PI3K-dependent operating on transcriptional initiation, whereas the other is mitogen-activated protein kinase-dependent operating on elongation.

Non-NASA Center↗