Cultures Of Parathyroid Cells Research Articles

The secretion of parathormone and glycosylated proteins by parathyroid cells in culture

The secretion of radioactive peptides by dispersed porcine parathyroid cells incubated with [ 3H]- or [ 14C]amino acids, [ 3H]glucosamine and [ 3H]mannose was analyzed. After incubation, the culture medium contained radioactive parathormone, as expected, and two radioactive glycopeptides: SP I and SP II. SP I appears to be identical with parathyroid secretory protein , heretofore not recognized as a glycoprotein. SP II has not been previously identified. SP I, but not SP II or parathormone, was adsorbed by Concanavalin A possibly reflecting a high mannose content of this molecule. Raising the concentration of calcium in the medium suppressed the secretion of radioactive parathormone and SP I in a similar fashion but did not affect the secretion of SP II. Our results suggest that SP I may play a fundamental role in parathyroid synthetic or secretory processes.

Studies on the Biosynthesis and Secretion of Parathyroid hormone in Monolayer Cultures of Bovine Parathyroid Cells (I)

We have developed a preparation of monolayer cultures of bovine parathyroid cells in order to elucidate the control mechanism of the biosynthesis and secretion of parathyroid hormone (PTH) at cellular level. Dispersion of parathyroid cells was performed by stirring minced bovine parathyroid tissues in Hanks' BSS containing 0.3 yields to 0.5 percent collagenase at 37 degrees C for 60 min. Dispersed cells were cultured at 37 degrees C in MEM-Hanks' BSS containing 10 percent fetal calf serum and 15 mM HEPES. On the 5th day of the culture, the medium was replaced with 1 percent BSA-MEM-Hanks-HEPES buffer, and the cells were incubated with 3H-leucine or in the media containing various concentrations of calcium, magnesium, PGE1, PGE2 or DBcAMP. At the end of incubation, the cells were detouched and homogenized in 8M urea, 0.2 N HCL and 0.01 M cysteine solution. The isolation of proparathyroid hormone (ProPTH) and PTH was performed through the preparation of TCA-powder followed by CMC column chromatography. PTH in the incubation medium was determined by radioimmunoassay. It was demonstrated that the monolayer cultures of bovine parathyroid cells were synthesizing ProPTH and converting it to PTH. The cultures exhibited linear secretion rates of PTH into the medium. The secretion of PTH was markedly increased by PGE1, PGE2 or DBcAMP in the range of 10(-7) yields to 10(-5)M in the former and 10(-5) yields to 10(-3)M in the latter, while calcium or magnesium changed secretion rate in the range of 0.3 yields to 4.4 mM.

Proceedings: The effect of insulin on parathyroid cells in culture.

Proceedings: The effect of insulin on parathyroid cells in culture.

Synthesis of human parathyroid hormone by cultured cells: evidence for release of prohormone by some adenomata.

1. Monolayer cultures of human parathyroid cells were established for a study of the nature of secreted human parathyroid hormone (HPTH). 2. [14C]Leucine and 75Se-labelled methionine were used as amino acid precursors for the biosynthesis of HPTH. 3. Immunoreactive labelled HPTH in the medium was extracted by affinity chromatography. 4. In cultures from glands, six adenomatous and one hyperplastic, radioactive HPTH in the media was indistinguishable in size and charge from highly purified bovine parathyroid hormone (PTH). 5. In two cultures from adenomata, media contained an immunoreactive basic peptide resembling ‘pro-PTH’ in its electrophoretic behaviour. The freeze-dried cells contained the same basic peptide.