Calcium-sensing receptor expression is regulated by glial cells missing-2 in human parathyroid cells.

Glial cells missing-2 (Gcm2) is the key regulating transcription factor for parathyroid gland development. The continued expression of high levels of Gcm2 in mature parathyroid glands suggests that it is required for maintenance of parathyroid cell differentiation. The role of Gcm2 in parathyroid cell physiology, however, has not been fully studied.

Destabilization of parathyroid hormone mRNA by extracellular Ca2+ and the calcimimetic R-568 in parathyroid cells: role of cytosolic Ca and requirement for gene transcription.

Extracellular Ca reduces parathyroid hormone (PTH) levels through several mechanisms, but many details of the intracellular steps involved have been difficult to elucidate because of the lack of a suitable parathyroid cell model. The present studies utilized our Ca-responsive bovine parathyroid organoid culture system (pseudoglands) to examine PTH mRNA in intact parathyroid cells. Increasing medium calcium from 0.

Differential effects of p27 in regulation of beta-cell mass during development, neonatal period, and adult life.

beta-Cell cycle progression and proliferation are critical to maintain beta-cell mass in adult mice. Of the cell cycle inhibitors, p27Kip1 is thought to be the primary modulator of the proliferative status in most cell types. p27 plays a role in beta-cell adaptation in genetic models of insulin resistance.

Akt induces beta-cell proliferation by regulating cyclin D1, cyclin D2, and p21 levels and cyclin-dependent kinase-4 activity.

Proliferation is the major component for maintenance of beta-cell mass in adult animals. Activation of phosphoinositide 3-kinase/Akt-kinase pathway is a critical regulator of beta-cell mass. Pancreatic beta-cell overexpression of constitutively active Akt in mice (caAkt(Tg)) resulted in marked expansion of beta-cell mass by increase in beta-cell proliferation and size.

Effect of age, vitamin D, and calcium on the regulation of rat intestinal epithelial calcium channels.

Transepithelial transport of calcium involves uptake at the apical membrane, movement across the cell, and extrusion at the basolateral membrane. Active vitamin D metabolites regulate the latter two processes by induction of calbindin D and the plasma membrane ATPase (calcium pump), respectively. The expression of calbindin D and the calcium pump declines with age in parallel with transepithelial calcium transport.

Regulation of enhanced vacuolar H+-ATPase expression in macrophages.

The proton-translocating vacuolar ATPase (V-ATPase) acidifies the endocytic network of eukaryotic cells. Although all eukaryotic cell types require low to moderate levels of V-ATPase, some proton-secreting cells express amplified levels for use in specialized membrane domains. To characterize genetic elements required for this heightened expression, we studied transcription and stability of mRNA encoding the V-ATPase c subunit in a low expressing fibroblast cell line (NIH 3T3) and a high expressing macrophage cell line (RAW 264.