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21.
Metyrapone, a specific inhibitor of 11beta-hydroxylase inhibits glucocorticoid production and it is used in the diagnosis/treatment of hypercortisolism and also to test the functional integrity of hypothalamo-pituitary-adrenal axis. To assess the impact of glucocorticoid deficiency, this drug is preferred over adrenalectomy, which eliminates all the hormonal secretions of the adrenal cortex and medulla. However, whether metyrapone has any direct effect on the extra-adrenocortical cellular or tissue functions remains to be resolved. Our previous study showed a depressed testicular Leydig cell testosterone production in rats treated with metyrapone. Therefore, the present study was designed to examine the possible direct effect of metyrapone on testicular Leydig cell steroidogenesis in vitro. Leydig cell viability and the reactive oxygen species (ROS) concentration were not altered by any of the concentration of metyrapone tested. The efficacy of Leydig cell testosterone production under basal as well as LH-stimulated condition was not altered by metyrapone treatment. Further, Leydig cellular (14)C-glucose oxidation, the activity and mRNA levels of cytochrome side chain cleavage (P(450)scc), 3beta- and 17beta-hydroxysteroid dehydrogenase (3beta-HSD and 17beta-HSD) were not altered in metyrapone-treated cells. Therefore, it is concluded from the present study that metyrapone has no direct effect on Leydig cell testosterone production and, therefore, changes recorded in the in vivo studies are exclusively due to corticosterone deficiency. 相似文献
22.
Muralidharan Muthu Yakir Ophir Lucy J. Macdonald Alankar Vaidya Gareth Lloyd-Jones 《Antonie van Leeuwenhoek》2018,111(12):2293-2301
The objective was to understand the roles of multiple catechol dioxygenases in the type strain Sphingobium scionense WP01T (Liang and Lloyd-Jones in Int J Syst Evol Microbiol 60:413–416, 2010a) that was isolated from severely contaminated sawmill soil. The dioxygenases were identified by sequencing, examined by determining the substrate specificities of the recombinant enzymes, and by quantifying gene expression following exposure to model priority pollutants. Catechol dioxygenase genes encoding an extradiol xylE and two intradiol dioxygenases catA and clcA that are highly similar to sequences described in other sphingomonads are described in S. scionense WP01T. The distinct substrate specificities determined for the recombinant enzymes confirm the annotated gene functions and suggest different catabolic roles for each enzyme. The role of the three enzymes was evaluated by analysis of enzyme activity in crude cell extracts from cells grown on meta-toluate, benzoate, biphenyl, naphthalene and phenanthrene which revealed the co-induction of each enzyme by different substrates. This was corroborated by quantifying gene expression when cells were induced by biphenyl, naphthalene and pentachlorophenol. It is concluded that the ClcA and XylE enzymes are recruited in pathways that are involved in the degradation of chlorinated aromatic compounds such as pentachlorophenol, the XylE and ClcA enzymes will also play a role in degradation pathways that produce alkylcatechols, while the three enzymes ClcA, XylE and CatA will be simultaneously involved in pathways that generate catechol as a degradation pathway intermediate. 相似文献
23.
Optical absorption, photoluminescence, thermoluminescence (TL) and photostimulated luminescence (PSL) studies on RbI:Tb(3+) crystals irradiated with gamma-rays is reported. Photoluminescence of these crystals exhibits characteristic Tb(3+) emissions, due to transitions from the (5)D(3) and (5)D(4) levels to various levels of the (7)F septet. On F-bleaching the gamma-irradiated crystals, Z(3) centres are observed. The TL glow curve indicates a two-step thermal annihilation process for the radiatively created defects. The presence of the characteristic emissions due to terbium ions in the photostimulation at the F-band, and TL emissions under both glow peaks, confirm the participation of Tb ions in the defect production and recombination processes. Trap parameters for the TL process are calculated and presented. The low temperature glow peak is attributable to Z(3) centres. 相似文献
24.
25.
26.
Dystrophin and utrophin link the F-actin cytoskeleton to the cell membrane via an associated glycoprotein complex. This functionality results from their domain organization having an N-terminal actin-binding domain followed by multiple spectrin-repeat domains and then C-terminal protein-binding motifs. Therapeutic strategies to replace defective dystrophin with utrophin in patients with Duchenne muscular dystrophy require full-characterization of both these proteins to assess their degree of structural and functional equivalence. Here the high resolution structures of the first spectrin repeats (N-terminal repeat 1) from both dystrophin and utrophin have been determined by x-ray crystallography. The repeat structures both display a three-helix bundle fold very similar to one another and to homologous domains from spectrin, α-actinin and plectin. The utrophin and dystrophin repeat structures reveal the relationship between the structural domain and the canonical spectrin repeat domain sequence motif, showing the compact structural domain of spectrin repeat one to be extended at the C-terminus relative to its previously defined sequence repeat. These structures explain previous in vitro biochemical studies in which extending dystrophin spectrin repeat domain length leads to increased protein stability. Furthermore we show that the first dystrophin and utrophin spectrin repeats have no affinity for F-actin in the absence of other domains. 相似文献
27.
Kaur Harsimran Shankarnarayana Shamanth A. Hallur Vinaykumar Muralidharan Jayashree Biswal Manisha Ghosh Anup K. Ray Pallab Chakrabarti Arunaloke Rudramurthy Shivaprakash M. 《Mycopathologia》2020,185(2):257-268
Mycopathologia - A sudden rise of Candida krusei candidemia cases was noticed in our hospital within 1 year with maximum cases from paediatric unit. The present study reports the results... 相似文献
28.
29.
Girish V. Shah Anbalagan Muralidharan Mitan Gokulgandhi Kamal Soan Shibu Thomas 《The Journal of biological chemistry》2009,284(2):1018-1030
Calcitonin, a neuroendocrine peptide, and its receptor are localized in the
basal epithelium of benign prostate but in the secretory epithelium of
malignant prostates. The abundance of calcitonin and calcitonin receptor mRNA
displays positive correlation with the Gleason grade of primary prostate
cancers. Moreover, calcitonin increases tumorigenicity and invasiveness of
multiple prostate cancer cell lines by cyclic AMP-dependent protein
kinase-mediated actions. These actions include increased secretion of matrix
metalloproteinases and urokinase-type plasminogen activator and an increase in
prostate cancer cell invasion. Activation of calcitonin-calcitonin receptor
autocrine loop in prostate cancer cell lines led to the loss of cell-cell
adhesion, destabilization of tight and adherens junctions, and internalization
of key integral membrane proteins. In addition, the activation of
calcitonin-calcitonin receptor axis induced epithelial-mesenchymal transition
of prostate cancer cells as characterized by cadherin switch and the
expression of the mesenchymal marker, vimentin. The activated calcitonin
receptor phosphorylated glycogen synthase kinase-3, a key regulator of
cytosolic β-catenin degradation within the WNT signaling pathway. This
resulted in the accumulation of intracellular β-catenin, its
translocation in the nucleus, and transactivation of β-catenin-responsive
genes. These results for the first time identify actions of
calcitonin-calcitonin receptor axis on prostate cancer cells that lead to the
destabilization of cell-cell junctions, epithelial-to-mesenchymal transition,
and activation of WNT/β-catenin signaling. The results also suggest that
cyclic AMP-dependent protein kinase plays a key role in calcitonin
receptor-induced destabilization of cell-cell junctions and activation of
WNT-β-catenin signaling.Prostate cancer
(PC)2 is the most
commonly diagnosed cancer and the second leading cause of cancer deaths in men
in the United States (1,
2). Although androgen ablation
therapy is effective in men with advanced disease for some time, the disease
subsequently progresses to the androgen-independent stage. The population of
prostate cells expressing neuroendocrine factors such as calcitonin (CT) also
increases during this progression
(3–5).
At this stage, the disease is metastatic and chemoresistant. Present evidence
suggests that cancer metastasis is usually preceded by the disruption of
normal cell-cell adhesion and the loss of integrity of the primary tumor site
(6,
7). This process may include
several genetic, molecular, and morphological changes characterized by
epithelial-to-mesenchymal transition (EMT)
(8–10).
The EMT is characterized by the loss of cell polarity, altered cell-cell and
cell-matrix adhesion, and acquisition of migratory, mesenchymal phenotype.
Other reported changes include down-regulation of E-cadherin, induction of
N-cadherin, release of β-catenin from junctional complexes, and its
translocation to the nucleus
(11–13).
However, the precise molecular mechanisms associated with this process are
obscure.Several growth factors, including hepatocyte growth factor, transforming
growth factor-β, vascular endothelial growth factor, and epidermal growth
factor, have been reported to induce EMT in tumor cell lines
(14–16).
We have shown that the expression of CT and its G protein-coupled receptor
(CTR) is remarkably higher in advanced PCs, and the CT-CTR autocrine axis is a
potent stimulator of PC cell tumorigenicity, invasion, and metastasis
(4,
17–19).
Although CT-stimulated increase in the motility and invasion of PC cells may
be mediated by CT-stimulated secretion of matrix metalloproteinases and
urokinase-type plasminogen activator, the precise molecular mechanisms
preceding these CTR actions remain to be elucidated
(18,
20). We tested the hypothesis
that CT induces biochemical and morphological changes associated with EMT to
increase the invasiveness of PC cells.Our results indicate that activation of the CT-CTR autocrine axis in
prostate cancer cells induced several changes associated with EMT such as
remodeling of tight and adherens junctions, cadherin switching, and activation
of WNT/β-catenin signaling. In contrast, the silencing of the CT-CTR axis
reversed this process. Moreover, cyclic AMP-dependent protein kinase (PKA)
plays a key role in this CT-CTR-mediated process. This is the first study
demonstrating the action of prostate CTR on junctional complexes and
WNT/β-catenin signaling of PC cell lines. 相似文献
30.
Anat Florentin David W. Cobb Heather M. Kudyba Vasant Muralidharan 《Cellular microbiology》2020,22(7)
The ability of eukaryotic parasites from the phylum Apicomplexa to cause devastating diseases is predicated upon their ability to maintain faithful and precise protein trafficking mechanisms. Their parasitic life cycle depends on the trafficking of effector proteins to the infected host cell, transport of proteins to several critical organelles required for survival, as well as transport of parasite and host proteins to the digestive organelles to generate the building blocks for parasite growth. Several recent studies have shed light on the molecular mechanisms parasites utilise to transform the infected host cells, transport proteins to essential metabolic organelles and for biogenesis of organelles required for continuation of their life cycle. Here, we review key pathways of protein transport originating and branching from the endoplasmic reticulum, focusing on the essential roles of chaperones in these processes. Further, we highlight key gaps in our knowledge that prevents us from building a holistic view of protein trafficking in these deadly human pathogens. 相似文献