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701.
Microphthalmia Gene Product as a Signal Transducer in cAMP-Induced Differentiation of Melanocytes 总被引:11,自引:0,他引:11
Corine Bertolotto Patricia Abbe Timothy J. Hemesath Karine Bille David E. Fisher Jean-Paul Ortonne Robert Ballotti 《The Journal of cell biology》1998,142(3):827-835
Islets of Langerhans are microorgans scattered throughout the pancreas, and are responsible for synthesizing and secreting pancreatic hormones. While progress has recently been made concerning cell differentiation of the islets of Langerhans, the mechanism controlling islet morphogenesis is not known. It is thought that these islets are formed by mature cell association, first differentiating in the primitive pancreatic epithelium, then migrating in the extracellular matrix, and finally associating into islets of Langerhans. This mechanism suggests that the extracellular matrix has to be degraded for proper islet morphogenesis. We demonstrated in the present study that during rat pancreatic development, matrix metalloproteinase 2 (MMP-2) is activated in vivo between E17 and E19 when islet morphogenesis occurs. We next demonstrated that when E12.5 pancreatic epithelia develop in vitro, MMP-2 is activated in an in vitro model that recapitulates endocrine pancreas development (Miralles, F., P. Czernichow, and R. Scharfmann. 1998. Development. 125: 1017–1024). On the other hand, islet morphogenesis was impaired when MMP-2 activity was inhibited. We next demonstrated that exogenous TGF-β1 positively controls both islet morphogenesis and MMP-2 activity. Finally, we demonstrated that both islet morphogenesis and MMP-2 activation were abolished in the presence of a pan-specific TGF-β neutralizing antibody. Taken together, these observations demonstrate that in vitro, TGF-β is a key activator of pancreatic MMP-2, and that MMP-2 activity is necessary for islet morphogenesis. 相似文献
702.
Picquet E Le Ny K Delépine P Montier T Yaouanc JJ Cartier D des Abbayes H Férec C Clément JC 《Bioconjugate chemistry》2005,16(5):1051-1053
Two new families of cationic lipids were designed and synthesized for gene delivery, namely "lipophosphoramidates" and "lipophosphoguanidines", whose efficiency was noteworthy. The most efficient have an arsonium cation as the polar head, and the unsaturated lipidic tails (e.g. oleyl) gave the better in vivo results (mice lungs). 相似文献
703.
Vertical jumping reorganization with aging: a kinematic comparison between young and elderly men 总被引:1,自引:0,他引:1
To our knowledge jumping kinematics have never been studied in elderly persons. This study was aimed at examining the influence of aging on vertical jump performance and on interjoint coordination. Two groups of adults, 11 young men ages 18-25 years and 11 older men ages 79-100 years, were filmed while performing a maximal squat jump. Compared to young adults, jump height was significantly decreased by 28 cm in the elderly. Older adults spontaneously jumped from a more extended position of the hip. Results showed a decrease in hip, knee, and ankle linear velocity and angular amplitude with aging. The decrease in jump height was attributed to a decrease in explosive force and in the range of shortening of extensor muscles. In agreement with the literature, a proximo-distal coordination pattern was observed in young adults. Older adults used a simultaneous pattern. This may indicate that adults adjust their pattern of joint coordination as they age. 相似文献
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705.
Garait B Couturier K Servais S Letexier D Perrin D Batandier C Rouanet JL Sibille B Rey B Leverve X Favier R 《Free radical biology & medicine》2005,39(9):1249-1261
Food restriction is the most effective modulator of oxidative stress and it is believed that a reduction in caloric intake per se is responsible for the reduced generation of reactive oxygen species (ROS) by mitochondria. Hydrogen peroxide (H(2)O(2)) generation and oxygen consumption (O(2)) by skeletal muscle mitochondria were determined in a peculiar strain of rats (Lou/C) characterized by a self-low-caloric intake and a dietary preference for fat. These rats were fed either with a standard high-carbohydrate (HC) or a high-fat (HF) diet and the results were compared to those measured in Wistar rats fed a HC diet. H(2)O(2) production was significantly reduced in Lou/C rats fed a HC diet; this effect was not due to a lower O(2) consumption but rather to a decrease in rotenone-sensitive NADH-ubiquinone oxidoreductase activity and increased expression of uncoupling proteins 2 and 3. The reduced H(2)O(2) generation displayed by Lou/C rats was accompanied by a significant inhibition of permeability transition pore (PTP) opening. H(2)O(2) production was restored and PTP inhibition was relieved when Lou/C rats were allowed to eat a HF diet, suggesting that the reduced oxidative stress provided by low caloric intake is lost when fat proportion in the diet is increased. 相似文献
706.
Perazzolo C Wist J Loth K Poggi L Homans S Bodenhausen G 《Journal of biomolecular NMR》2005,33(4):233-242
Major urinary protein (MUP) is a pheromone-carrying protein of the lipocalin family. Previous studies by isothermal titration
calorimetry (ITC) show that the affinity of MUP for the pheromone 2-methoxy-3-isobutylpyrazine (IBMP) is mainly driven by
enthalpy, with a small unfavourable entropic contribution. Entropic terms can be attributed in part to changes in internal motions of the protein upon binding. Slow internal motions can lead to correlated or anti-correlated modulations of the isotropic chemical shifts of carbonyl C′ and amide N nuclei. Correlated chemical shift modulations (CSM/CSM) in MUP
have been determined by measuring differences of the transverse relaxation rates of zero- and double-quantum coherences ZQC{C′N}
and DQC{C′N}, and by accounting for the effects of correlated fluctuations of dipole–dipole couplings (DD/DD) and chemical
shift anisotropies (CSA/CSA). The latter can be predicted from tensor parameters of C′ and N nuclei that have been determined
in earlier work. The effects of complexation on slow time-scale protein dynamics can be determined by comparing the temperature
dependence of the relaxation rates of APO-MUP (i.e., without ligand) and HOLO-MUP (i.e., with IBMP as a ligand).
Electronic supplementary material Electronic supplementary material is available for this article at
and accessible for authorised users. 相似文献
707.
Liger D Quevillon-Cheruel S Sorel I Bremang M Blondeau K Aboulfath I Janin J van Tilbeurgh H Leulliot N 《Proteins》2005,60(4):778-786
In the Pseudomonas bacterial genomes, the PhzF proteins are involved in the production of phenazine derivative antibiotic and antifungal compounds. The PhzF superfamily however also encompasses proteins in all genomes from bacteria to eukaryotes, for which no function has been assigned. We have determined the three dimensional crystal structure at 2.05 A resolution of YHI9, the yeast member of the PhzF family. YHI9 has a fold similar to bacterial diaminopimelate epimerase, revealing a bimodular structure with an internal symmetry. Residue conservation identifies a putative active site at the interface between the two domains. Evolution of this protein by gene duplication, gene fusion and domain swapping from an ancestral gene containing the "hot dog" fold, identifies the protein as a "kinked double hot dog" fold. 相似文献
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710.
Sophie Boyer Karine Faure Florence Ader Marie Odile Husson Eric Kipnis Thierry Prangere Xavier Leroy Benoit P Guery 《Respiratory research》2005,6(1):17