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K G Peters J Marie E Wilson H E Ives J Escobedo M Del Rosario D Mirda L T Williams 《Nature》1992,358(6388):678-681
Stimulation of certain receptor tyrosine kinases results in the tyrosine phosphorylation and activation of phospholipase C gamma (PLC gamma), an enzyme that catalyses the hydrolysis of phosphatidylinositol (PtdIns). This hydrolysis generates diacylglycerol and free inositol phosphate, which in turn activate protein kinase C and increase intracellular Ca2+, respectively. PLC gamma physically associates with activated receptor tyrosine kinases, suggesting that it is a substrate for direct phosphorylation by these kinases. Here we report that a fibroblast growth factor (FGF) receptor with a single point mutation at residue 766 replacing tyrosine with phenylalanine fails to associate with PLC gamma in response to FGF. This mutant receptor also failed to mediate PtdIns hydrolysis and Ca2+ mobilization after FGF stimulation. However, the mutant receptor phosphorylated itself and several other cellular proteins, and it mediated mitogenesis in response to FGF. These findings show that a point mutation in the FGF receptor selectively eliminates activation of PLC gamma and that neither Ca2+ mobilization nor PtdIns hydrolysis are required for FGF-induced mitogenesis. 相似文献
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Friis EM Crane PR Pedersen KR Bengtson S Donoghue PC Grimm GW Stampanoni M 《Nature》2007,450(7169):549-552
Over the past 25 years the discovery and study of Cretaceous plant mesofossils has yielded diverse and exquisitely preserved fossil flowers that have revolutionized our knowledge of early angiosperms, but remains of other seed plants in the same mesofossil assemblages have so far received little attention. These fossils, typically only a few millimetres long, have often been charred in natural fires and preserve both three-dimensional morphology and cellular detail. Here we use phase-contrast-enhanced synchrotron-radiation X-ray tomographic microscopy to clarify the structure of small charcoalified gymnosperm seeds from the Early Cretaceous of Portugal and North America. The new information links these seeds to Gnetales (including Erdtmanithecales, a putatively closely related fossil group), and to Bennettitales--important extinct Mesozoic seed plants with cycad-like leaves and flower-like reproductive structures. The results suggest that the distinctive seed architecture of Gnetales, Erdtmanithecales and Bennettitales defines a clade containing these taxa. This has significant consequences for hypotheses of seed plant phylogeny by providing support for key elements of the controversial anthophyte hypothesis, which links angiosperms, Bennettitales and Gnetales. 相似文献
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Stephanie Duguez William Duddy Helen Johnston Jeanne Lainé Marie Catherine Le Bihan Kristy J. Brown Anne Bigot Yetrib Hathout Gillian Butler-Browne Terence Partridge 《Cellular and molecular life sciences : CMLS》2013,70(12):2159-2174
Duchenne muscular dystrophy results from loss of the protein dystrophin, which links the intracellular cytoskeletal network with the extracellular matrix, but deficiency in this function does not fully explain the onset or progression of the disease. While some intracellular events involved in the degeneration of dystrophin-deficient muscle fibers have been well characterized, changes in their secretory profile are undescribed. To analyze the secretome profile of mdx myotubes independently of myonecrosis, we labeled the proteins of mdx and wild-type myotubes with stable isotope-labeled amino acids (SILAC), finding marked enrichment of vesicular markers in the mdx secretome. These included the lysosomal-associated membrane protein, LAMP1, that co-localized in vesicles with an over-secreted cytoskeletal protein, myosin light chain 1. These LAMP1/MLC1-3-positive vesicles accumulated in the cytosol of mdx myotubes and were secreted into the culture medium in a range of abnormal densities. Restitution of dystrophin expression, by exon skipping, to some 30 % of the control value, partially normalized the secretome profile and the excess LAMP1 accumulation. Together, our results suggest that a lack of dystrophin leads to a general dysregulation of vesicle trafficking. We hypothesize that disturbance of the export of proteins through vesicles occurs before, and then concurrently with, the myonecrotic cascade and contributes chronically to the pathophysiology of DMD, thereby presenting us with a range of new potential therapeutic targets. 相似文献
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Ludivine A. Pradelli Marie Bénéteau Jean-Ehrland Ricci 《Cellular and molecular life sciences : CMLS》2010,67(10):1589-1597
Mitochondria control whether a cell lives or dies. The role mitochondria play in deciding the fate of a cell was first identified
in the mid-1990s, because mitochondria-enriched fractions were found to be necessary for activation of death proteases, the
caspases, in a cell-free model of apoptotic cell death. Mitochondrial involvement in apoptosis was subsequently shown to be
regulated by Bcl-2, a protein that was known to contribute to cancer in specific circumstances. The important role of mitochondria
in promoting caspase activation has therefore been a major focus of apoptosis research; however, it is also clear that mitochondria
contribute to cell death by caspase-independent mechanisms. In this review, we will highlight recent findings and discuss
the mechanism underlying the mitochondrial control of apoptosis and caspase-independent cell death. 相似文献