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Rcd1, initially identified as a factor essential for the commitment to nitrogen starvation-invoked differentiation in fission yeast, is one of the most conserved proteins found across eukaryotes, and its mammalian homolog is expressed in a variety of differentiating tissues. Here we show that mammalian Rcd1 is a novel transcriptional cofactor and is critically involved in the commitment step in the retinoic acid-induced differentiation of F9 mouse teratocarcinoma cells, at least in part, via forming complexes with retinoic acid receptor and activation transcription factor-2 (ATF-2). In addition, antisense oligonucteotide treatment of embryonic mouse lung explants suggests that Rcd1 also plays a role in retinoic acid-controlled lung development. [ABSTRACT FROM AUTHOR]

Background Previously, we reported that Sema3A, one of the secreted repulsive axon guidance molecules, CRMP (collapsin response mediator protein)-2, a putative intracellular signalling molecule for Sema3A and Sema3A receptor neuropilin-1 are expressed in the developing lung. Sema3A inhibits branching morphogenesis of embryonic lung in organ culture. Results We examined the gene expression of Sema3A, Sema3C, Sema3F and their receptors, NP-1, NP-2 and plexin-A1 by in situ hybridization. Transcripts of all six genes were detected in mouse lung from embryonic day E11.5 to E17.5, and displayed highly specific spatiotemporal distributions. The distribution of the receptor genes was detected in patterns which were consistent with known receptor usage of the semaphorins. In contrast to Sema3A, we found that the other class 3 semaphorins, Sema3C and Sema3F, stimulated branching morphogenesis. This stimulatory effect of Sema3C or Sema3F was accompanied by a moderate increase in the incorporation of bromodeoxyuridine (BrdU) into DNA in the terminal epithelial cells. Conclusion The coordinated expression patterns of different semaphorins and their receptors, together with the specific activities affecting branching morphogenesis, suggest that the semaphorins act as both positive and negative regulators of branching morphogenesis in the developing lung. [ABSTRACT FROM AUTHOR]

Brefeldin A induces a rapid redistribution of cost proteins associated with clathrin-coated vesicles that bud from the tans-Golgi network but not of those associated with vesicles derived from the plasma membrane. Its effect on glucose transport and the subcellular distribution of the glucose transporter CLUT4 were therefore investigated in the absence or in the presence of insulin in order to characterize the mechanism of insulin-induced GLUT4 recycling. Exposure of rat adipose cells to befeldin A in the absence of insulin resulted in a slight increase both in 3-O-methyl-D-glocose transport and in the amount of GLUT4 in the plasma membrane as determined by immunoblot analysis. In contrast, it had no effect on the insulin-induced increase in 3-O-methyl-glucose transport and plasma-membrane-associated GLUT4. Immunohistochemical analysis revealed clathrin immunoreactivity in the juxtanuclear region and in the cell periphery, and the staining in the perinuclear region decreased after exposure of cells to 35 μM brefeldin A. However, it had no effect on the basal pattern of GLUT4 staining or on the insulin-induced redistribution of GLUT4 staining to the cell periphery. These results suggest that basal recycling of GLUT4 responsible for maintaining the intracellular location of the transporter may include a membrane budding step sensitive to brefeldin A, possibly associated with clathrin-coated vesicles, but that the insulin-stimulated GLUT4 recycling pathway is mediated predominatly by a brefeldin A-insensitive mechanism. [ABSTRACT FROM AUTHOR]