Cytophysiology of Thyroid Parafollicular Cells

Nunez, Eladio A.; Gershon, Michael D.

doi:10.1016/s0074-7696(08)60753-6

Cited by 55 publications

(26 citation statements)

References 309 publications

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“…This is different from other mammals such as cat, dog, rabbit and rat were they are numerous (Lupulescu & Petrovici, 1968) and in deer thyroid (Pantic, 1967) and many mammalian hibernators, but they are very rare in many primates including human thyroids (Nunez & Gershon, 1978). The role of parafollicular cells in calcium metabolism through calcitonin in most mammals studied is most likely similar in WAD goats.…”

Section: Discussionmentioning

confidence: 85%

Ultrastructure of the Thyroid Gland in Adult West African Dwarf Goat (Capra hircus)

2015

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. Ultrastructure of the thyroid gland in adult West African dwarf goat (Capra hircus). Int. J. Morphol., 33(2):532-537, 2015. SUMMARY:The present study examined ultrastructure of the thyroid gland of adult West African Dwarf (WAD) goat in order to further understand the ultrastructural morphology and some of the changes in the components of the thyroid gland in goat with age. Thyroids glands obtained from fifteen adult WAD goats of different ages and sexes slaughtered at the local abattoirs were used in this study. Electron microscopic techniques were used to study the fixed tissue with emphasis on the follicular and parafollicular cells. The results showed that the ultrastructure is generally similar to that of some domestic animals. Follicular cells were cuboidal in young adult goats thyroids but were flattened in older goat thyroids of 5-7 years. These cells remarkably showed highly dilated cisternae of rough endoplasmic reticulum which decreased in frequency the older goats. Microvilli were short and sparse on the follicular cells and the number decreased in the older goats. Different sizes of apical vesicles of varying electron density were encountered that included colloid droplets, secretory vesicles and lysosome-like bodies and the appearance of these vesicles changed with age. Parafollicular cells were encountered in the basal position between follicular cells in all thyroids examined. Numerous dense cytoplasmic granules were observed and they were not apparently different from that described in several mammals.

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Section: Discussionmentioning

confidence: 85%

Ultrastructure of the Thyroid Gland in Adult West African Dwarf Goat (Capra hircus)

2015

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“…As a result, PF cells secrete both transmitters when stimulated by their natural secretogogue, increased extracellular Ca 2ϩ (1[Ca 2ϩ ] e ) (Nunez and Gershon, 1978). PF cells are able to respond to 1 [Ca 2ϩ ] e because they express a plasmalemmal Ca 2ϩ receptor (CaR) that is activated by changes in the extracellular Ca 2ϩ concentration and polyamines, such as protamine (Herbert and Brown, 1995;Tamir et al, 1996).…”

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confidence: 99%

Ca²⁺-Evoked Serotonin Secretion by Parafollicular Cells: Roles in Signal Transduction of Phosphatidylinositol 3′-kinase, and the γ and ζ Isoforms of Protein Kinase C

et al. 2000

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Parafollicular (PF) cells secrete 5-HT in response to stimulation of a G-protein-coupled Ca 2ϩ receptor (CaR) by increased extracellular Ca 2ϩ (1[Ca 2ϩ ] e ). We tested the hypothesis that protein kinase C (PKC) participates in stimulus-secretion coupling. Immunoblots from membrane and cytosolic fractions of isolated PF cells revealed conventional (␣, ␤I, and ␥), novel (␦ and ⑀), and atypical ( / and ) PKCs. Only PKC␥ was found to have been translocated to the membrane fraction when secretion of 5-HT was evoked by 1[Ca 2ϩ ] e or phorbol esters. Although phorbol downregulation caused PKC␥ to disappear, secretion was only partially inhibited. A similar reduction of 1[Ca 2ϩ ] e -evoked secretion was produced by inhibitors of conventional and/or novel PKCs (Gö 6976, calphostin C, and pseudoA), and these compounds did not inhibit secretion at all when applied to phorbol-downregulated cells. In contrast, the phorbol downregulation-resistant component of secretion was abolished by pseudoZ, which inhibits the atypical PKC . Stimulation of PF cells with 1[Ca 2ϩ ] e increased the activity of immunoprecipitated PKC (but not PKC / ), and the activity of this PKC was inhibited by pseudoZ. PF cells were found to express regulatory (p85) and catalytic (p110␣ and p110␤) subunits of phosphatidylinositol 3Ј-kinase (PI3Ј-kinase). 1[Ca 2ϩ ] e increased the activity of immunoprecipitated PI3Ј-kinase; moreover, PI3Ј-kinase inhibitors (wortmannin and LY294002) antagonized secretion. We suggest that PKC isoforms mediate secretion of 5-HT by PF cells in response to stimulation of the CaR. PKC involvement can be accounted for by PKC␥ and an isoform sensitive to inhibition by pseudoZ, probably PKC , which is activated via PI3Ј-kinase.

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“…Increases in serum Ca¥ stimulate parafollicular cells of the thyroid gland (PF cells) to release calcitonin (CT) and serotonin (5_HT) (Nunez & Gershon, 1978). PF cells, along with those of the parathyroid gland, are able to detect ambient Ca¥ levels and this sensitivity controls the release of the hormones that regulate calcium homeostasis.…”

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confidence: 99%

“…While CT affects distant targets to influence Ca¥ homeostasis, 5_HT acts locally to regulate follicular cells (Tamir et al , 1996. PF cells are localized within the basal lamina surrounding each follicle of the thyroid (Nunez & Gershon, 1978) and their relatively low abundance has hindered detailed physiological analyses. Instead, medullary thyroid carcinoma (MTC) cell lines, which are derived from PF cells and are also sensitive to increases in [Ca¥]ï, have been used as models for PF cell biochemical and biophysical characteristics (Muff et al 1988;Yamashita & Hagiwara 1990;Fajtova, Quinn & Brown, 1991;Mekonnen, Raue & Ziegler, 1992;DeReimer, Hsiung & Tamir, 1992;Scherubl, Kleppisch, Zink, Raue, Krautwurst & Hescheler, 1993; for a review see Nelkin, 1996).…”

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confidence: 99%

Mechanism of extracellular Ca²⁺ receptor‐stimulated hormone release from sheep thyroid parafollicular cells

McGehee

Aldersberg

Liu

et al. 1997

The Journal of Physiology

109

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1. Expression of receptors to extracellular calcium enables parafollicular cells of the thyroid gland (PF cells) to release calcitonin (CT) and serotonin (5_HT) in response to increased external Ca¥. Recently, a calcium-sensing receptor (CaR), similar to the G protein-coupled receptor for external Ca¥ cloned from parathyroid gland, was shown to be expressed in PF cells. Using a highly purified preparation of sheep PF cells, we have examined the electrical and biochemical processes coupling CaR activation to hormone release. cation is Ca¥, indicating that influx via the cation conductance is another source of the increases in [Ca¥]é. 6. Extracellular Ca¥ stimulates 5_HT release with an ECÛÑ of 1·5 mÒ. Nimodipine blocks 90% of the Cafi-induced 5_HT release, while other inhibitors of voltage-gated calcium channels had no effect. These data support an important role for L-type Ca¥ channels in CaR-induced hormone secretion. Although earlier studies indicate that high [Ca¥]ï induces release of Ca¥ from intracellular stores, thapsigargin-induced depletion of these stores did not affect secretion from these cells, indicating that Ca¥ influx is necessary and sufficient for the Cafi-induced 5_HT secretion. 7. Inhibition of protein kinase C (PKC) using chelerythrine, staurosporine, or calphostin C inhibited Cafi-induced 5_HT release by 50% while phorbol ester-induced 5_HT secretion was completely inhibited. Thus, PKC is an important component of the pathway linking CaR activation to hormone release. However, another as yet unknown second messenger also contributes to this pathway. 8. We tested the contribution of two different phospholipases to the CaR responses to determine the source of the PKC activator diacylglycerol (DAG). Selective inhibition of phosphatidylinositol-specific phospholipase C (PI-PLC) with U73122 had no effect on the response to elevated [Ca¥]ï. However, pretreatment with D609, a selective inhibitor of phosphatidylcholine-specific phospholipase C (PC-PLC), inhibited Ca¥-induced 5_HT release to 50% of control indicating that phosphatidylcholine is a likely source of DAG in the response of PF cells to elevated [Ca¥]ï.

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Cytophysiology of Thyroid Parafollicular Cells

Cited by 55 publications

References 309 publications

Ultrastructure of the Thyroid Gland in Adult West African Dwarf Goat (Capra hircus)

Ultrastructure of the Thyroid Gland in Adult West African Dwarf Goat (Capra hircus)

Ca²⁺-Evoked Serotonin Secretion by Parafollicular Cells: Roles in Signal Transduction of Phosphatidylinositol 3′-kinase, and the γ and ζ Isoforms of Protein Kinase C

Mechanism of extracellular Ca²⁺ receptor‐stimulated hormone release from sheep thyroid parafollicular cells

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Cytophysiology of Thyroid Parafollicular Cells

Cited by 55 publications

References 309 publications

Ultrastructure of the Thyroid Gland in Adult West African Dwarf Goat (Capra hircus)

Ultrastructure of the Thyroid Gland in Adult West African Dwarf Goat (Capra hircus)

Ca2+-Evoked Serotonin Secretion by Parafollicular Cells: Roles in Signal Transduction of Phosphatidylinositol 3′-kinase, and the γ and ζ Isoforms of Protein Kinase C

Mechanism of extracellular Ca2+ receptor‐stimulated hormone release from sheep thyroid parafollicular cells

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Ca²⁺-Evoked Serotonin Secretion by Parafollicular Cells: Roles in Signal Transduction of Phosphatidylinositol 3′-kinase, and the γ and ζ Isoforms of Protein Kinase C

Mechanism of extracellular Ca²⁺ receptor‐stimulated hormone release from sheep thyroid parafollicular cells