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131.
INTRODUCTI0NThedifferentiati0nofcelIsalongthemonocyte-macr0phagepathwayandthesig-nalsinvo1vedinthesecel1sacquiringtheabilitytokilltum0rcellsarenotfllllyundersto0d.Wehavebeenstudingamoleculewhichappearst0beanimportantmemberofthecytokinenetworkinvo1vedintheregulati0nmonocyteactivation.ThiscytokinetermedP48wasisolatedfr0mthehllmannullcellleukemiacell1ineReh.IthasbeenpurifiedtohomogeneityandfOundtobedistinctfrominterferongamma,col0nystimulatingfactors(CSFs)andTNFalphaalldbeta[1,2].Func-ti… 相似文献
132.
Pathways that control cortical F-actin dynamics during secretion 总被引:2,自引:0,他引:2
Trifaró JM Lejen T Rosé SD Pene TD Barkar ND Seward EP 《Neurochemical research》2002,27(11):1371-1385
Chromaffin cells possess a mesh of filamentous actin underneath the plasma membrane which acts as a barrier to the chromaffin vesicles access to exocytotic sites. Disassembly of cortical F-actin in response to stimulation allows the movement of vesicles from the reserve pool to the release-ready vesicle pool and, therefore, to exocytotic sites. The dynamics of cortical F-actin is controlled by two mechanisms: a) stimulation-induced Ca2+ entry and scinderin activation and b) protein kinase C (PKC) activation and MARCKS phosphorylation as demonstrated here by experiments with recombinant proteins, antisense olygodeoxynucleotides and vector mediated transient expressions. Under physiological conditions (i.e., cholinergic receptor stimulation followed by Ca2+ entry), mechanism (a) is the most important for the control of cortical F-actin network whereas when Ca2+ is released from intracellular stores (i.e., histamine stimulation) cortical F-actin is regulated mainly by mechanism b. 相似文献
133.
Sighvatur S. Árnason Erik Skadhauge 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1991,161(1):1-14
Summary The plasma levels of four osmoregulatory hormones and their target ion-transport systems in the lower intestines of the domestic fowl were determined in order to elucidate their interrelationship and their setpoints in relation to NaCl intake. White Plymouth Rock hens were adapted to six intake levels of NaCl (0.20±0.02–24.7±1.9 mmoles Na+·kg bw–1·day–1) for 6 weeks. The Na+ absorption and the Cl– secretion of colon and coprodeum were characterized in vitro by the effects of hexoses, amino acids, amiloride, and theophylline on the short-circuit current (SCC) and electrical potential difference (PD). The NaCl-conserving system of the adult chicken is set at low intake levels of NaCl as the 80% range (quantitized by non-linear, logistic regression analyses) of the change in the plasma [ALDO], the amiloride-inhibitable Na+ absorption of coprodeum and colon ( SCC), occurred from 0.18 to 2.3, from 0.9 to 4.3, and from 1.2 to 7.3 mmoles Na+·kg bw–1·day–1, respectively. These results demonstrate that the amiloride-inhibitable Na+ absorption of coprodcum is more closely linked to plasma [ALDO] than that of colon. The aminoacid-Na+ coabsorption of colon increased over exactly the same range of Na+ intake as the colonic amiloride-inhibitable Na+ absorption decreased, whereas the hexose-Na+ coabsorption increased at higher levels of Na+ intake, from 2 to 11 mmoles Na+·kg bw–1·day–1. Both these Na+ absorption types had reached their maximums at 24.7 mmoles Na+·kg bw–1·day–1, whereas the plasma [AVT] and plasma [PRL], although significantly increased, apparently had not; their 80% range of change occurred from 9.9 to 99 mmoles Na+·kg bw–1·day–1, and the main changes in plasma osmolity were predicted to occur from 5.4 to 107 mmoles Na+·kg bw–1·day–1. These results suggest that these colonic and hormonal variables conserve osmotically-free water and operate at high NaCl intake. The theophylline-induced colonic Cl– secretion did not change with NaCl intake, whereas the stimulation of SCC in coprodeum decreased with increasing NaCl intake: The main change occurred between 0 and 3.2 mmoles Na+·kg bw–1·day–1. Thus, all ion-transport capacity disappears in coprodeum with increased dietary NaCl intake, whereas colon maintains its ion-transport capacity (although the nature of the Na+ transport changes). It is suggested that hormones defending the extracellular volume and composition are regulated close to zero input and output of both NaCl and water, regardless of whether they are NaCl conserving or free-water conserving. Therefore, changes in their stable plasma concentrations occur at the extremes of tolerable range of NaCl intake.Abbreviation
AA
aminoacids
-
ALDO
aldosterone
-
AMI
amiloride
-
AVT
arginine vasotocin
-
bw
body weight
-
CS
corticosterone
-
HEX
hexoses
-
INDO
indomethacin
-
PD
potential difference
-
PRL
prolactin
-
R
resistance
-
SCC
short-circuit current
-
SD
standard deviation
-
SEM
standard error of mean
-
THEO
theophylline 相似文献
134.
Anthraquinones produced by suspension cultures of Galium vernum are completely retained intracellularly. Surprisingly, in the presence of some polymeric adsorbents anthraquinones are partially released into the culture medium. The secretion and in situ removal stimulates anthraquinone production in cell cultures of Galium vernum. Best results were obtained with Wofatit ES and Amberlite XAD-2.Abbreviations DW
dry weight
- MS
Murashige & Skoog[7]medium
- NAA
1-naphthaleneacetic acid 相似文献
135.
136.
内分泌细胞和神经细胞通过释放激素和神经肽类物质来响应外界刺激,而这些物质的分泌,都是通过致密核心囊泡(dense core vesicle,DCV)来实现的.但是,现阶段关于DCV的生成、转运、释放的机制很大程度上是不清楚的.在本研究中,我们将线虫的排便行为和肠道分泌联系起来,并以此表型进行全基因组RNAi筛选,寻找调节DCV的新基因.我们成功筛选到了一些在肠道调节DCV生成或释放的基因.其中,CAB-1被确认为特异性调节DCV分泌的重要因子.在肠道中,cab-1突变会降低肠道DCV内容物的分泌,而在神经系统中,CAB-1的缺失也会导致DCV的标识物堆积在突触前,而突触囊泡(synaptic vesicle,SV)不受影响. 相似文献
137.
Jursky F Fuchs K Buhr A Tretter V Sigel E Sieghart W 《Journal of neurochemistry》2000,74(3):1310-1316
A chimeric GABA(A) receptor subunit was constructed that contained the beta3 sequence from the N-terminus to the first two amino acids of the second transmembrane (TM2) domain. The remaining part of this chimera had the sequence of the alpha1 subunit. On co-expression with alpha1 subunits, this chimera was able to form heterooligomeric channels that were open in the absence of GABA. Picrotoxin and tert-butylbicyclophosphorothionate (TBPS) were able to block these channels with low potency. These channels exhibited high-affinity [3H]muscimol but no high-affinity [35S]TBPS binding sites. Introduction of V251, A252, and L253 of the beta3 subunit into the chimera resulted in the formation of closed channels that could be opened by GABA. The introduction of A252 and L253 of the beta3 subunit into this chimera was sufficient to reconstitute the specific high-affinity [35S]TBPS binding site in receptors composed of the chimera and alpha1 subunits. Replacement of other amino acids of the TM2 region of the chimera with corresponding amino acids of the beta3 subunit modulated the affinity of this [35S]TBPS binding site. Results obtained provide important information on the structure-function relationship of GABA(A) receptors. 相似文献
138.
TFG clusters COPII‐coated transport carriers and promotes early secretory pathway organization 下载免费PDF全文
Adam Johnson Nilakshee Bhattacharya Michael Hanna Janice G Pennington Amber L Schuh Lei Wang Marisa S Otegui Scott M Stagg Anjon Audhya 《The EMBO journal》2015,34(6):811-827
In mammalian cells, cargo‐laden secretory vesicles leave the endoplasmic reticulum (ER) en route to ER‐Golgi intermediate compartments (ERGIC) in a manner dependent on the COPII coat complex. We report here that COPII‐coated transport carriers traverse a submicron, TFG (Trk‐fused gene)‐enriched zone at the ER/ERGIC interface. The architecture of TFG complexes as determined by three‐dimensional electron microscopy reveals the formation of flexible, octameric cup‐like structures, which are able to self‐associate to generate larger polymers in vitro. In cells, loss of TFG function dramatically slows protein export from the ER and results in the accumulation of COPII‐coated carriers throughout the cytoplasm. Additionally, the tight association between ER and ERGIC membranes is lost in the absence of TFG. We propose that TFG functions at the ER/ERGIC interface to locally concentrate COPII‐coated transport carriers and link exit sites on the ER to ERGIC membranes. Our findings provide a new mechanism by which COPII‐coated carriers are retained near their site of formation to facilitate rapid fusion with neighboring ERGIC membranes upon uncoating, thereby promoting interorganellar cargo transport. 相似文献
139.
deMello DE Mahmoud S Padfield PJ Hoffmann JW 《In vitro cellular & developmental biology. Animal》2000,36(6):374-382
Summary This paper describes a new fully differentiated Type-II alveolar epithelial cell line designated T7, derived from transgenic H-2Kb-tsA58 mice, capable of being passaged as an immortalized cloned cell line in culture. H-2Kb-tsA58 mice harbor a temperature-sensitive (ts) mutant of the simian virus 40 (SV40) large tumor antigen (T antigen) under
the control of the γ-interferon (INF)-inducible mouse major histocompatibility complex H-2Kb promoter. When cultured under permissive conditions (33°C and in the presence of γ-INF) cells isolated from H-2Kb-tsA58 mice express the large T antigen, which drives the cells to proliferate. However, upon withdrawal of the γ-INF and
transfer of the cells to a higher temperature (39°C), T antigen expression is turned off, the cells stop proliferating and
differentiate. The T7 cell line is a clonal cell line originally derived from a Type-II cell-rich fraction isolated from lungs of H-2Kb-tsA58 mice. The T7 cells form confluent monolayers, and have a polarized epithelial cell morphology with tight junctions and apical microvilli.
In addition, the T7 cells have distinct cytoplasmic lamellar bodies, which become more numerous and pronounced when the cells are grown under
nonpermissive conditions. The T7 cells synthesize and secrete phosphatidylcholine and the three surfactant proteins, SP-A, SP-B, and SP-C. The T7 cell line is unique in that it is the first non-tumor-derived Type-II cell line capable of synthesizing and secreting the
major components of surfactant. Based on the criteria studied, the T7 cell line is phenotypically very similar to normal Type-II cells. The T7 cell line, therefore, should prove a valuable experimental system to advance the study of the cell biology/physiology of
surfactant metabolism and secretion as well as serve as a model for other studies of Type-II cell physiology. 相似文献
140.
Olaf Sparre Andersen 《The Journal of general physiology》1997,109(1):1-2
Stimulated secretion in endocrine cells and neuronal synapses causes a rise in endocytosis rates to recover the added membrane. The endocytic process involves the mechanical deformation of the membrane to produce an invagination. Studies of osmotic swelling effects on endocytosis indicate that the increased surface tension is tightly correlated to a significant decrease of endocytosis. When rat basophilic leukemia (RBL) cells are stimulated to secrete, there is a dramatic drop in the membrane tension and only small changes in membrane bending stiffness. Neither the shape change that normally accompanies secretion nor the binding of ligand without secretion causes a drop in tension. Further, tension decreases within 6 s, preceding shape change and measurable changes in endocytosis. After secretion stops, tension recovers. On the basis of these results we suggest that the physical parameter of membrane tension is a major regulator of endocytic rate in RBL cells. Low tensions would stimulate endocytosis and high tensions would stall the endocytic machinery. 相似文献