Developmental and functional studies of parvalbumin and calbindin D28K in hypothalamic neurons grown in serum-free medium.
The Ca2+-binding proteins parvalbumin (Mr = 12K) and calbindin D28K [previously designated vitamin D-dependent Ca2+-binding protein (Mr = 28K)] are neuronal markers, but their functional roles in mammalian brain are unknown. The expression of these two proteins was studied by immunocytochemical methods in serum-free cultures of hypothalamic cells from 16-day-old fetal mice. Parvalbumin is first detected in all immature neurons, but during differentiation, the number of parvalbumin-immunoreactive neurons greatly declines to a level reminiscent of that observed in vivo, where only a subpopulation of neurons stains for parvalbumin. In contrast, calbindin D28K was expressed throughout the period investigated only in a distinct subpopulation of neurons. Depolarization of fully differentiated hypothalamic neurons in culture resulted in a dramatic decrease of parvalbumin immunoreactivity but not of calbindin D28K immunoreactivity. The parvalbumin staining was restored on repolarization. Because the anti-parvalbumin serum seems to recognize only the metal-bound form of parvalbumin, the loss of immunoreactivity may signal a release of Ca2+ from intracellular parvalbumin during depolarization of the cells. We suggest that parvalbumin might be involved in Ca2+-dependent processes associated with neurotransmitter release.
Pfyffer
G E
GE
Faivre-Bauman
A
A
Tixier-Vidal
A
A
Norman
A W
AW
Heizmann
C W
CW
D000818:Animals; D064092:Calbindin 1; D064026:Calbindins; D002455:Cell Division; D002478:Cells, Cultured; D005333:Fetus; D005455:Fluorescent Antibody Technique; D007031:Hypothalamus / Q000166:cytology* / Q000196:embryology; D051379:Mice; D008970:Molecular Weight; D009124:Muscle Proteins / Q000096:biosynthesis*; D009474:Neurons / Q000166:cytology*; D010320:Parvalbumins / Q000032:analysis / Q000096:biosynthesis*; D064030:S100 Calcium Binding Protein G / Q000032:analysis / Q000096:biosynthesis*
C576499:Calb1 protein, mouse; D064092:Calbindin 1; D064026:Calbindins; D009124:Muscle Proteins; D010320:Parvalbumins; D064030:S100 Calcium Binding Protein G