scholarly journals Cytochalasin-stimulated steroidogenesis from high density lipoproteins

1978 ◽  
Vol 77 (2) ◽  
pp. 507-516 ◽  
Author(s):  
F Cortese ◽  
J Wolf
Keyword(s):  
Cytochalasin B ◽  
Adrenal Tumor ◽  
Rapid Onset ◽  
High Density ◽  
High Density Lipoproteins ◽  
Short Term ◽  
Produce Cell ◽  
Adrenal Cells ◽  
Low Concentrations ◽  
Cytochalasin E

The cytochalasins stimulate steroid secretion of Y-1 adrenal tumor cells two-to threefold. The order of potencies is cytochalasin E is greater than D is greater than B, but the maximum response is the the same and always less than with ACTH. Like that with ACTH, the stimulation has a rapid onset, is easily reversible, is inhibited by cucloheximide and aminoglutethimide, and occurs at a stage before pregnenolone. Although the cytochalasin, like ACTH, produce cell rounding, it is shown that this morphological change is not necessarily coupled to steridogenesis. Unlike ACTH, cytochalasin B does not measurably increase cellular levels of cAMP at concentrations that lead to maximal steroidogenesis. The cytochalasin B-induced stimulation of steroidogenesis, unlike the short-term ACTH effect, fails to occur in the absence of serum. This lack of response can be corrected by even low concentrations of human high density lipoproteins (HDL) but not by low density lipoproteins (LDL). We, therefore, propose that cytochalasin B enhances the availability of cholesterol bound to HDL for steroidogenesis by Y-1 adrenal cells.

scholarly journals Cytochalasins inhibit nuclei-induced actin polymerization by blocking filament elongation.

1980 ◽  
Vol 84 (2) ◽  
pp. 455-460 ◽  
Author(s):  
D C Lin ◽  
K D Tobin ◽  
M Grumet ◽  
S Lin
Keyword(s):  
Binding Sites ◽  
Actin Polymerization ◽  
Cytochalasin B ◽  
Molecular Size ◽  
Muscle Actin ◽  
Competitive Displacement ◽  
Low Concentrations ◽  
Relative Affinity ◽  
Cytochalasin E ◽  
Low Ionic Strength

Polylysine was found to induce polymerization of muscle actin in a low ionic strength buffer containing 0.4 mM MgCl2. The rate of induced polymerization was dependent on the amount and on the molecular size of the polylysine added. A similar effect was obtained by adding actin nuclei (containing about 2-4 actin subunits) cross-linked by p-N,N'-phenylenebismaleimide to G-actin under the same conditions, suggesting that the effect of polylysine is due to promotion of the formation of actin nuclei. Polymerization induced by polylysine and by cross-linked actin nuclei was inhibited by low concentrations (10(-8)-10(-6)M) of cytochalasins. Binding experiments showed that actin filaments, but not actin monomers, contained high-affinity binding sites for [3H]cytochalasin B (one site per 600 actin monomers). The relative affinity of several cytochalasins for these sites (determined by competitive displacement of [3H]dihydrocytochalasin B) was: cytochalasin D greater than cytochalasin E approximately equal to dihydrocytochalasin B. The results of this study suggest that cytochalasins inhibit nuclei-induced actin polymerization by binding to highly specific sites at the point of monomer addition, i.e., the elongation site, in actin nuclei and filaments.

Densitometry of phosphatidylcholine and sphingomyelin in high-density lipoproteins.

1983 ◽  
Vol 29 (7) ◽  
pp. 1435-1437 ◽  
Author(s):  
G Schmitz ◽  
H U Jabs ◽  
G Assmann
Keyword(s):  
Sulfuric Acid ◽  
Phosphotungstic Acid ◽  
High Density ◽  
High Density Lipoproteins ◽  
Low Concentrations ◽  
Layer Chromatography ◽  
Inexpensive Technique ◽  
Native Plasma ◽  
Enzymatic Methods

Abstract We describe the quantitative densitometric determination of phosphatidylcholine (PC) and sphingomyelin (SP) in human serum after precipitation with phosphotungstic acid/MgCl2 and use of thin-layer chromatography. After development, chromatographic plates were charred with methanolic sulfuric acid and MnCl2 and scanned by direct reflectance densitometry in an automated densitometric system interfaced to a basic programmable computing integrator. The method is sensitive enough to detect abnormally low concentrations of PC and SP in high-density lipoproteins. The accuracy of the method was tested either with the Bartlett phosphorus assay or with enzymatic methods for PC and SP; correlations of the described method with the enzymatic determinations were r = 0.93 and 0.88, respectively. Day-to-day precision (CV) for the phospholipid determination was 8.6% for PC and 12.2% for SP. The major advantage of this inexpensive technique is that native plasma or serum or the serum supernate after precipitation can be used without prior delipidation. With this technique serum high-density lipoproteins had PC values of 1.08 (SD 0.32) mmol/L in men (n = 158) and 1.12 (SD 0.37) mmol/L in women (n = 192); similarly, SP values were 0.23 (SD 0.07) mmol/L in the men and 0.23 (SD 0.08) mmol/L in the women. The differences by sex are not significant.

scholarly journals Impact of Short-Term Administration of High-Density Lipoproteins and Atorvastatin on Atherosclerosis in Rabbits

2005 ◽  
Vol 25 (11) ◽  
pp. 2416-2421 ◽  
Author(s):  
Stephen J. Nicholls ◽  
Belinda Cutri ◽  
Stephen G. Worthley ◽  
Patrick Kee ◽  
Kerry-Anne Rye ◽  
...  
Keyword(s):  
High Density ◽  
High Density Lipoproteins ◽  
Short Term ◽  
Term Administration

scholarly journals Importance of Apolipoprotein A-I and A-II Composition in HDL and Its Potential for Studying COVID-19 and SARS-CoV-2

Medicines ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 38
Author(s):  
Kyung-Hyun Cho
Keyword(s):  
Antiviral Activity ◽  
High Density ◽  
High Density Lipoproteins ◽  
Potent Antiviral Activity ◽  
Apolipoprotein A ◽  
Putative Role

The composition and properties of apolipoprotein (apo) A-I and apoA-II in high-density lipoproteins (HDL) might be critical to SARS-CoV-2 infection via SR-BI and antiviral activity against COVID-19. HDL containing native apoA-I showed potent antiviral activity, while HDL containing glycated apoA-I or other apolipoproteins did not. However, there has been no report to elucidate the putative role of apoA-II in the antiviral activity of HDL.

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