Exocytotic protein components in rat pituitary gland after long-term estrogen administration.

Recently, a set of proteins involved in the docking and fusion machinery of secretory organelles has been identified in anterior pituitary cells. In this study we analyzed, by Western blotting and immunocytochemistry, the expression of several proteins involved in exocytosis after long-term administration of 17beta-estradiol (E2) in Fischer 344 rats. No differences were observed in the amount of synaptosomal-associated protein of 25 kDa, synaptobrevin 2, syntaxin 1, synaptotagmin I and Rab3a in total brain homogenates from treated rats after E2 administration.

Syntaxin 1A and 1B display distinct distribution patterns in the rat peripheral nervous system.

Syntaxin 1 has been shown to play an outstanding role in synaptic vesicle exocytosis. Two isoforms of this protein are expressed in neurons, syntaxin 1A and 1B. However, the physiological significance of the occurrence of such closely related isoforms is not still understood.

Trk neurotrophin receptor family immunoreactivity in rat and human pituitary tissues.

Several lines of evidence suggest that neurotrophins may be involved in pituitary function. By immunocytochemical methods we analyzed the cellular distribution of their functional receptors in the pituitary gland. In the rat pituitary gland Trks were differentially distributed.

Immunocytochemical analysis of the synaptic proteins SNAP-25 and Rab3A in human pituitary adenomas. Overexpression of SNAP-25 in the mammmosomatotroph lineages.

SNAP-25 and Rab3A were originally identified as synaptic proteins involved in neuronal membrane traffic. Recently, both proteins have been detected in several mammalian endocrine cell types and have been proposed as essential components of the exocytotic pathway in neuroendocrine cells. In this study, the expression of SNAP-25 and Rab3A was analysed in biopsied human anterior pituitary tumours (21 cases) by immunocytochemical methods.

Synaptobrevin isoforms in secretory granules and synaptic-like microvesicles in anterior pituitary cells.

A set of synaptic proteins have been shown to be essential for the life cycle and exocytosis of synaptic vesicles at the nerve terminal. Recently, these proteins have also been identified in certain endocrine cells. Here we analysed the presence and location of some of these synaptic proteins in anterior pituitary cells.

Regulated secretion is impaired in AtT-20 endocrine cells stably transfected with botulinum neurotoxin type A light chain.

Botulinum neurotoxin type A (BoNT/A) inhibits neurotransmitter release by specific cleavage of SNAP-25, a synaptosome-associated protein also expressed in the ACTH secretory cell line AtT-20. Expression of light chain BoNT/A (L-BoNT/A) gene transfected into AtT-20 cells resulted in a cleaved form of SNAP-25 indistinguishable from that generated by bona fide BoNT/A. L-BoNT/A-transfected cells showed no difference in replication rate, viability, or phenotype, compared with control AtT-20 cells.

Differential distribution of syntaxin isoforms 1A and 1B in the rat central nervous system.

Syntaxin 1 binds to several proteins of the synaptic terminal and is a central component in the pathway of protein-protein interactions that underlies docking and fusion of synaptic vesicles. Molecular studies revealed the occurrence of two isoforms, syntaxin 1A and syntaxin 1B, which coexpress in neural tissues. However, they display differential expression patterns in endocrine cell types.

Expression of synaptosomal-associated protein SNAP-25 in endocrine anterior pituitary cells.

A growing body of evidence indicates that the fundamental molecular mechanism of exocytosis in the secretory pathway may be structurally similar in all eukaryotic cells. The synaptosomal-associated protein of 25 kDa (SNAP-25) is a plasma membrane protein involved in regulated exocytosis in neurons. In order to compare exocytotic components in neurons and endocrine cells, we have analyzed the expression of SNAP-25 in the rat anterior pituitary.

Cloning characterization and expression of the cDNA encoding a neuron-specific alpha-tubulin isoform highly represented in the electric lobe of Torpedo marmorata.

A cDNA (alpha T6) encoding an alpha-tubulin from Torpedo marmorata (Tm) was isolated and sequenced. The deduced 451-amino-acid (aa) sequence codes for an alpha-tubulin of 50,161 Da. The aa sequence of alpha T6 of Tm showed a 70-99.