High α‐amylase activity in the syncytiotrophoblastic cells of first‐trimester human placentas

Fisher, Susan J.; Laine, Roger A.

doi:10.1002/jcb.240220105

Cited by 12 publications

(3 citation statements)

References 16 publications

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“…One study found some immunostaining in luminal secretions but not in syncytiotrophoblast samples ( Jones et al 2015 ). Another study found high α-amylase activity in first-trimester human placentas ( Fisher & Laine 1983 ). Finally, glycogen could be broken down in the autophagosome by the enzyme acid α-glucosidase ( Koutsifeli et al 2022 ).…”

Section: Metabolism and Secretion Of Nutrients By The Uterine Epitheliummentioning

confidence: 95%

Endometrial glucose metabolism during early pregnancy

Chen,

Dean

2023

Reproduction and Fertility

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Approximately 50% of human pregnancies humans fail, most before or during implantation. One factor contributing to pregnancy loss is abnormal glucose metabolism in the endometrium. Glucose contributes to preimplantation embryo development, uterine receptivity, and attachment of the embryo. Across multiple species, the epithelium stores glucose as the macromolecule glycogen at estrus. This reserve is mobilized during the preimplantation period. Glucose from circulation or glycogenolysis can be secreted into the uterine lumen for use by the embryo or metabolized via glycolysis, producing ATP for the cell. The resulting pyruvate could be converted to lactate, another important nutrient for the embryo. Fructose is an important nutrient for early embryos, and the epithelium and placenta can convert glucose to fructose via the polyol pathway. The epithelium also uses glucose to glycosylate proteins, which regulates embryo attachment. In some species, decidualization of the stroma is critical to successful implantation. Formation of the decidua requires increased glucose metabolism via the pentose phosphate pathway and glycolysis. After decidualization, the cells switch to aerobic glycolysis to produce ATP. Paradoxically, the decidua also stores large amounts of glucose as glycogen. Too little glucose or an inability to take up glucose impairs embryo development and decidualization. Conversely, too much glucose inhibits these same processes. This likely contributes to the reduced pregnancy rates associated with conditions like obesity and diabetes. Collectively, precise control of glucose metabolism is important for several endometrial processes required to establish a successful pregnancy. The factors regulating these metabolic processes remain poorly understood.

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Section: Metabolism and Secretion Of Nutrients By The Uterine Epitheliummentioning

confidence: 95%

Endometrial glucose metabolism during early pregnancy

Chen,

Dean

2023

Reproduction and Fertility

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“…The luminal cytoplasm contains vesicles surrounded by flat membranes. The remaining cytoplasm contains a large number of rough and smooth endoplasmic reticulum, a well-developed Golgi complex, and numerous mitochondria [ 9 ].…”

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confidence: 99%

Severe preeclampsia complicated by HELLP syndrome alters the structure of Hofbauer and syncytiotrophoblast cells: ultrastructural and immunohistochemical study

Nergiz,

Deveci,

Sak

et al. 2023

Asian Biomedicine

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Background Hemolysis, elevated liver enzymes, low platelet count (HELLP) syndrome is generally considered to be a variant or complication of preeclampsia. It is a life-threatening obstetric complication. Objectives To evaluate the immunohistochemistry and ultrastructural of syncytiotrophoblastand Hoffbauer cells in placental villi of patients with HELLP syndrome. Methods Two groups of patients with a total of 50 full-term human placentas (n = 25 in each group) were assigned as the control (normotensive) and HELLP syndrome. Placental tissue samples were fixed in 10% neutral formalin and paraffin-embedding protocol was performed. We prepared 5 μm sections for histological and immunohistochemical staining. Sections were immunostained with Hoffbauer cell marker CD68. For transmission electron microscopy (TEM), placental tissue samples were fixed in 2.5% buffered glutaraldehyde and then, in 1% osmium tetroxide for routine ultrastructural examinations. Results When the HELLP group fetal placental sections were examined, intracytoplasmic edema in syncytiotrophoblast, degenerative vacuoles, and degenerative findings on cell surface membranes were observed. Moreover, villous edema was remarkable. The number of CD68-positive Hoffbauer cells per villus control group sections was 0.23 ± 0.02 and the number of CD68-positive cells per villus in HELLP group placenta sections was 0.83 ± 0.12. The increase in the number of Hoffbauer cells per villus in the HELLP group was significant (P < 0.001). Compared with the control group, there was a significant increase in the number of Hoffbauer cells and syncytiotrophoblasts in the HELLP group, and degenerative changes were also observed in the ultrastructure of these cells. Conclusions Pathology of the HELLP syndrome is in relation to CD68-positive placental macrophages.

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“…In addition, the brush border of the early placenta is also rich in glycogen and the enzymes that synthesize and degrade this molecule. In contrast, preparations of microvilli from term placentas contain no demonstrable glycogen (Fisher & Laine, 1981, 1984.…”

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confidence: 99%

External labelling of glycoproteins from first-trimester human placental microvilli

Fisher¹,

Leitch²,

Laine³

1984

Biochemical Journal

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The brush-border glycoproteins of first-trimester human placentas were investigated by using two external labelling techniques: (1) sequential digestion with neuraminidase and galactose oxidase, followed by reduction with NaB3H4, which 3H-labels terminal galactose and galactosamine residues; and (2) sequential treatment with periodate and NaB3H4, which 3H-labels terminal sialic acid residues. The labelling procedures were performed on intact tissue so that the results would more closely approximate the topography of the brush border in vivo. The microvilli were isolated, subjected to sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, and the [3H]glycoproteins detected by fluorography. Densitometer scans of the fluorograms of the [3H]galactoproteins showed that, under reducing conditions, 90% of the protein-associated radioactivity was incorporated into two glycoproteins. The major [3H]galactoprotein of early placental microvilli had an estimated molecular mass of 92 kDa (desialylated) and migrated as a diffuse band. A minor 180 kDa glycoprotein was less consistently labelled. No change in the apparent molecular mass of either component was detected in the absence of beta-mercaptoethanol, suggesting that the 180 kDa component was not a dimer of the 92 kDa glycoprotein. The remaining 10% the radioactivity was equally distributed among several minor membrane components. Densitometer scans of the fluorograms of the [3H]sialoproteins showed that, under either reducing or non-reducing conditions, 90% of the 3H was preferentially incorporated into the 92-110 kDa region of the gel. Although no distinct bands were visible, the higher-molecular-mass region of this area was always most heavily labelled. A minor 180 kDa glycoprotein was also 3H-labelled. The pattern of brushborder [3H]glycoproteins from first-trimester placentas differed markedly from that of term placental microvilli and from placental fibroblast plasma membranes that were 3H-labelled by identical external labelling techniques. These results indicate that: (1) the glycoprotein determinants of brush-border topography change during pregnancy; (2) within the placenta, the major 92 kDa (desialylated) determinant, which has not been previously described, is unique to the trophoblastic cells.

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High α‐amylase activity in the syncytiotrophoblastic cells of first‐trimester human placentas

Cited by 12 publications

References 16 publications

Endometrial glucose metabolism during early pregnancy

Endometrial glucose metabolism during early pregnancy

Severe preeclampsia complicated by HELLP syndrome alters the structure of Hofbauer and syncytiotrophoblast cells: ultrastructural and immunohistochemical study

External labelling of glycoproteins from first-trimester human placental microvilli

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