scholarly journals Stereochemical requirements for the modulation by retinoic acid of thyroid hormone activation of Ca2+-ATPase and binding at the human erythrocyte membrane

1992 ◽  
Vol 284 (2) ◽  
pp. 583-587 ◽  
Author(s):  
T J Smith ◽  
F B Davis ◽  
P J Davis
Keyword(s):  
Retinoic Acid ◽  
Fatty Acid ◽  
Thyroid Hormone ◽  
Erythrocyte Membrane ◽  
Human Erythrocyte ◽  
Binding Sites ◽  
Erythrocyte Membranes ◽  
Side Chain ◽  
Acid Molecule

Physiological concentrations of retinoic acid can block the activation of human erythrocyte Ca(2+)-ATPase in vitro by thyroid hormone [Smith, Davis & Davis (1989) J. Biol. Chem. 264, 687-689]. The present studies were undertaken to ascertain the nature of this blockade. Two binding sites for L-thyroxine (T4) were demonstrated on washed erythrocyte membranes; the high-affinity site had a Kd value of 2.7 x 10(-10)M and a Bmax. of 76 fmol/mg of protein. The lower-affinity site possessed a Kd of 1 x 10(-8) M. Retinoic acid was as potent a displacer of radiolabelled T4 as was the unlabelled hormone. Certain retinoic acid analogues with either ring or fatty acid side chain modifications retained some ability to displace [125I]T4 binding and to block iodothyronine activation of Ca(2+)-ATPase. The side chain terminal carboxyl group was essential for full activity of the retinoic acid molecule. Its absence or replacement with an ethylsulphone group rendered the molecule considerably less active in the ATPase model. Retinol, 13-cis-retinoic acid, benzene-substituted all-trans-retinoic acid and polyprenoic acid all failed to influence iodothyronine binding or to block activation of Ca(2+)-ATPase by T4. There was good agreement between the ability of an analogue to displace [125I]iodothyronine binding and its ability to inhibit the T4-dependent activation of the Ca(2+)-ATPase. It would appear from these observations that retinoic acid can modulate the activation of erythrocyte membrane Ca(2+)-ATPase by thyroid hormone through a mechanism which involves displacement of iodothyronine from binding sites. These activities apparently derive from both the ring structure and the fatty acid side chain of the retinoic acid molecule.

Thyroid hormone stimulates release of calmodulin-enhancing activity from human erythrocyte membranes in vitro

1993 ◽  
Vol 84 (2) ◽  
pp. 217-223 ◽  
Author(s):  
William D. Lawrence ◽  
Mark R. Deziel ◽  
Paul J. Davis ◽  
Marion Schoenl ◽  
Faith B. Davis ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Human Erythrocyte ◽  
Erythrocyte Membranes ◽  
Soluble Factor ◽  
Heat Stable ◽  
Enhancing Factor ◽  
Human Erythrocyte Membranes ◽  
Subsequent Addition ◽  
Stable Control

1. Thyroid hormone (L-thyroxine, 10−10mol/l) incubated in vitro with human erythrocyte membranes induced the release of a soluble calmodulin-like material, the 3′:5′-cyclic nucleotide phosphodiesterase-stimulating activity of which was at least six-fold greater than its concentration measured by a specific calmodulin radioimmunoassay. 2. The material had the characteristics of calmodulin in that it stimulated both phosphodiesterase and erythrocyte Ca2+-ATPase activities, cross-reacted with and was neutralized by anti-calmodulin antibody, was adsorbed by phenothiazine-Sepharose and was heat-stable. Control supernatant from the incubation of membranes in the absence of thyroxine contained calmodulin, the bioactivity of which was not enhanced beyond that predicted from radioimmunoassay. Subsequent addition of thyroxine did not increase calmodulin bioactivity. Calmodulin-agarose removed calmodulin-enhancing activity from the supernatant. 3. Thus, the enhancing factor(s) appears to interact directly with calmodulin. These observations indicate that thyroid hormone promotes the release from human erythrocyte membranes of a soluble factor (or factors) which binds to calmodulin and significantly increases its bioactivity. This enhancing activity is similar to that of a calmodulin activator described in a rat model of hypertension (S.-L. Huang et al., J Clin Invest 1988; 82: 276-81).

scholarly journals Necator americanus Ancylostoma Secreted Protein-2 (Na-ASP-2) Binds an Ascaroside (ascr#3) in Its Fatty Acid Binding Site

2020 ◽  
Vol 8 ◽  
Author(s):  
Ola El Atab ◽  
Rabih Darwiche ◽  
Nathanyal J. Truax ◽  
Roger Schneiter ◽  
Kenneth G. Hull ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Small Molecules ◽  
Binding Sites ◽  
Structural Basis ◽  
Side Chain ◽  
Secreted Protein ◽  
Competition Assay ◽  
Fatty Acid Binding ◽  
Binding Cavity

During their infective stages, hookworms release excretory-secretory (E-S) products, small molecules, and proteins to help evade and suppress the host's immune system. Small molecules found in E-S products of mammalian hookworms include nematode derived metabolites like ascarosides, which are composed of the sugar ascarylose linked to a fatty acid side chain. The most abundant proteins found in hookworm E-S products are members of the protein family known as Ancylostoma secreted protein (ASP). In this study, two ascarosides and their fatty acid moieties were synthesized and tested for in vitro binding to Na-ASP-2 using both a ligand competition assay and microscale thermophoresis. The fatty acid moieties of both ascarosides tested and ascr#3, an ascaroside found in rat hookworm E-S products, bind to Na-ASP-2's palmitate binding cavity. These molecules were confirmed to bind to the palmitate but not the sterol binding sites. An ascaroside, oscr#10, which is not found in hookworm E-S products, does not bind to Na-ASP-2. More studies are required to determine the structural basis of ascarosides binding by Na-ASP-2 and to understand the physiological significance of these observations.

scholarly journals Thyroid Hormone Signaling in Embryonic Stem Cells: Crosstalk with the Retinoic Acid Pathway

2020 ◽  
Vol 21 (23) ◽  
pp. 8945
Author(s):  
Mercedes Fernández ◽  
Micaela Pannella ◽  
Vito Antonio Baldassarro ◽  
Alessandra Flagelli ◽  
Giuseppe Alastra ◽  
...  
Keyword(s):  
Stem Cells ◽  
Retinoic Acid ◽  
Embryonic Stem Cells ◽  
Thyroid Hormone ◽  
Nuclear Receptors ◽  
Embryonic Stem ◽  
Embryoid Bodies ◽  
Postnatal Life ◽  
Gene And Protein Expression

While the role of thyroid hormones (THs) during fetal and postnatal life is well-established, their role at preimplantation and during blastocyst development remains unclear. In this study, we used an embryonic stem cell line isolated from rat (RESC) to study the effects of THs and retinoic acid (RA) on early embryonic development during the pre-implantation stage. The results showed that THs play an important role in the differentiation/maturation processes of cells obtained from embryoid bodies (EB), with thyroid hormone nuclear receptors (TR) (TRα and TRβ), metabolic enzymes (deiodinases 1, 2, 3) and membrane transporters (Monocarboxylate transporters -MCT- 8 and 10) being expressed throughout in vitro differentiation until the Embryoid body (EB) stage. Moreover, thyroid hormone receptor antagonist TR (1-850) impaired RA-induced neuroectodermal lineage specification. This effect was significantly higher when cells were treated with retinoic acid (RA) to induce neuroectodermal lineage, studied through the gene and protein expression of nestin, an undifferentiated progenitor marker from the neuroectoderm lineage, as established by nestin mRNA and protein regulation. These results demonstrate the contribution of the two nuclear receptors, TR and RA, to the process of neuroectoderm maturation of the in vitro model embryonic stem cells obtained from rat.

scholarly journals Sex-dependent inhibition by retinoic acid of thyroid-hormone action on rabbit reticulocyte Ca2+-ATPase activity

1991 ◽  
Vol 273 (2) ◽  
pp. 489-492
Author(s):  
F B Davis ◽  
T J Smith ◽  
P J Davis ◽  
W D Lawrence ◽  
A J Ryan ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Thyroid Hormone ◽  
Atpase Activity ◽  
Specific Interaction ◽  
Thyroid Hormone Action ◽  
Steroid Dependent ◽  
Dependent Inhibition ◽  
Gender Specific ◽  
Dependent Factor

The interaction was examined in vitro of retinoic acid and thyroid hormone with rabbit reticulocyte Ca2(+)-ATPase. L-Thyroxine (T4) (0.1 nM) stimulated female-source Ca2(+)-ATPase activity (+21%; P less than 0.03) and inhibited male-source enzyme (-20%; P less than 0.05). Addition of retinoic acid (10 nM-1 microM) did not influence T4-inhibitable male-source Ca2(+)-ATPase, but caused a 52% loss of T4 effect on the female-source enzyme. Incubation of female-source membranes with testosterone caused the enzyme response to T4 and retinoic acid to become that of male-source membranes, and the male-source enzyme response was converted into the ‘female’ pattern by exposure to 17 beta-oestradiol. We postulate that a membrane-associated sex-steroid-dependent factor imparts a gender-specific interaction of thyroid hormone and retinoic acid on Ca2(+)-ATPase, and that ultimately the factor is shed during erythrocyte maturation.

scholarly journals Membrane glycopeptides from old and young human erythrocytes (Short Communication)

1974 ◽  
Vol 140 (3) ◽  
pp. 557-560 ◽  
Author(s):  
Cesare Balduini ◽  
Carlo Luigi Balduini ◽  
Edoardo Ascari
Keyword(s):  
Sialic Acid ◽  
Erythrocyte Membrane ◽  
Human Erythrocyte ◽  
Short Communication ◽  
Chemical Characterization ◽  
Erythrocyte Membranes ◽  
Main Peak ◽  
Human Erythrocyte Membranes ◽  
Papain Digestion

Glycopeptides were extracted by papain digestion from old and young human erythrocyte membranes and fractionated on DEAE-Sephadex A-25. Chemical characterization of the unfractionated samples and of the main peak eluted from the column indicates that glycoproteins of the erythrocyte membrane undergo significant decreases in sialic acid and galactosamine content with aging.

scholarly journals Incorporation and Clearance of Omega-3 Fatty Acids in Erythrocyte Membranes and Plasma Phospholipids

2006 ◽  
Vol 52 (12) ◽  
pp. 2265-2272 ◽  
Author(s):  
Jing Cao ◽  
Kerry A Schwichtenberg ◽  
Naomi Q Hanson ◽  
Michael Y Tsai
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Fish Oil ◽  
Erythrocyte Membrane ◽  
Flaxseed Oil ◽  
Erythrocyte Membranes ◽  
Omega 3 Fatty Acids ◽  
Omega 3 ◽  
Fatty Acid Supplementation ◽  
Plasma Phospholipids

Abstract Background: The sum of eicosapentaenoic acid (EPA, 20:5 ω3) and docosahexaenoic acid (DHA, 22:6 ω3) in erythrocyte membranes, termed the omega-3 index, can indicate suboptimal intake of omega-3 fatty acids, a risk factor for cardiovascular disease (CVD). To study the effects of fatty acid supplementation, we investigated the rate of incorporation and clearance of these fatty acids in erythrocyte membranes and plasma after intake of supplements. Methods: Twenty study participants received supplementation with either fish oil (1296 mg EPA + 864 mg DHA/day) or flaxseed oil (3510 mg alpha-linolenic acid + 900 mg linoleic acid/day) for 8 weeks. We obtained erythrocyte membrane and plasma samples at weeks 0, 4, 8, 10, 12, 14, 16, and 24 and extracted and analyzed fatty acids by gas chromatography. Results: After 8 weeks of fish oil supplementation, erythrocyte membrane EPA and DHA increased 300% (P <0.001) and 42% (P <0.001), respectively. The mean erythrocyte omega-3 index reached a near optimal value of 7.8%, and remained relatively high until week 12. EPA and DHA showed greater increases and more rapid washout period decreases in plasma phospholipids than in erythrocyte membranes. Flaxseed oil supplementation increased erythrocyte membrane EPA to 133% (P <0.05) and docosapentaenoic acid (DPA, 22:5 ω3) to 120% (P <0.01) of baseline, but DHA was unchanged. In plasma phospholipids, EPA, DPA, and DHA showed a slight but statistically insignificant increase. Conclusions: Erythrocyte membrane EPA+DHA increases during relatively short intervals in response to supplementation at rates related to amount of supplementation. These results may be useful to establish appropriate dosage for omega-3 fatty acid supplementation.

scholarly journals Glycation of the human erythrocyte glucose transporter in vitro and its functional consequences

1990 ◽  
Vol 268 (3) ◽  
pp. 661-667 ◽  
Author(s):  
P J Bilan ◽  
A Klip
Keyword(s):  
Erythrocyte Membrane ◽  
Human Erythrocyte ◽  
Glucose Transporter ◽  
Cytochalasin B ◽  
Competitive Inhibitor ◽  
Human Erythrocyte Membrane ◽  
Functional Consequences ◽  
High Concentrations ◽  
Erythrocyte Membrane Proteins

Glycation of human erythrocyte membrane proteins was induced by incubation in vitro with high concentrations (80 mM or 200 mM) of D-glucose for 3 or 6 days. The extent of glycation was quantified from the covalent incorporation of 3H by reduction of the glucose glycation products with NaB3H4. For membranes incubated for 3 days with 80 mM-D-glucose, glycation in vitro of Band 4.5 (containing the glucose transporter) was equivalent to 0.11 mol of glucose/mol of glucose transporter, compared with 3H labelling in 3-day-incubated control membranes of 0.055 mol of glucose/mol of glucose transporter. In membranes incubated for 6 days with 200 mM-D-glucose, glycation increased to 0.21 mol of glucose/mol of glucose transporter, whereas the controls without glucose had 0.11 mol of glucose/mol of glucose transporter. Glycation in vitro was accompanied by a fall in the Bmax of binding of [3H]cytochalasin B (a competitive inhibitor of glucose transport), without any change in the binding affinity. The data suggest that glycated glucose transporters have decreased ability to bind cytochalasin B. It is proposed that glycation can alter glucose transporter activity.

scholarly journals Electron microscope study of reassociation of spectrin and actin with the human erythrocyte membrane

1981 ◽  
Vol 90 (1) ◽  
pp. 70-77 ◽  
Author(s):  
S Tsukita ◽  
S Tsukita ◽  
H Ishikawa ◽  
S Sato ◽  
M Nakao
Keyword(s):  
Erythrocyte Membrane ◽  
Human Erythrocyte ◽  
Actin Filaments ◽  
Actin Polymerization ◽  
Erythrocyte Membranes ◽  
Human Erythrocyte Membrane ◽  
Thin Sections ◽  
Fixation Treatment ◽  
Human Erythrocyte Membranes ◽  
Inside Out

Reassociation of spectrin and actin with human erythrocyte membranes was studied by stereoscopic electron microscopy of thin sections combined with tannic acid- glutaraldehyde fixation. Treatment of the erythrocyte membrane with 0.1 mM EDTA (pH 8.0) extracted more than 90 percent of the spectrin and actin and concomitantly removed filamentous meshworks underlying the membranes, followed by fragmentation into small inside-out vesicles. When such spectrin-depleted vesicles were incubated with the EDTA extract (crude spectrin), a filamentous meshwork, similar to those of the original membranes, was reformed on the cytoplasmic surface of the vesicles. The filamentous components, with a uniform thickness of 9 nm, took a tortuous course and joined one another often in an end-to-end fashion to form a irregular but continuous meshwork parallel to the membrane. Purified spectrin was also reassociated with the vesicles in a population density of filamentous components almost comparable to that of the crude spectrin-reassociated vesicles. However, the meshwork formation was much smaller in extent, showing many independent filamentous components closely applied to the vesicle surface. When muscle G-actin was added to the crude spectrin- or purified spectrin- reassociated vesicles under conditions which favor actin polymerization, actin filaments were seen to attach to the vesicles through the filamentous components. Two modes of association of actin filaments with the membrane were seen: end-to-membrane and side-to- membrane associations. In the end-to-membrane association, each actin filament was bound with several filamentous components exhibiting a spiderlike configuration, which was considered to be the unit of the filamentous meshwork of the original erythrocyte membrane.

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