Biomedical subjects

H Chneiweiss

Publications and source records attributed to H Chneiweiss.

44 records · Page 3Linked to original sources

PubMed1989

Stathmin is a major phosphoprotein and cyclic AMP-dependent protein kinase substrate in mouse brain neurons but not in astrocytes in culture: regulation during ontogenesis.

Stathmin is a ubiquitous soluble protein (Mr approximately 19,000; pI approximately 6.2-5.5) whose phosphorylation is associated with the intracellular mechanisms involved in the regulations of cell differentiation and functions by extracellular effectors. It is present in various tissues and cell types and has several nonphosphorylated and increasingly phosphorylated forms, and it is particularly abundant in brain. Very high concentrations of stathmin were also detected in mouse embryo striatal neurons grown in primary culture, whereas stathmin was barely detectable in astrocytes from the same source. Stathmin appeared in neurons as a major substrate for protein phosphorylation and, in particular, for the cyclic AMP (cAMP)-dependent protein kinase, because its phosphorylation was stimulated by cAMP in cell-free preparations and in intact cells by forskolin, a potent activator of adenylate cyclase. During brain ontogenesis, stathmin was first detected at embryonic day 12; its concentration increased until birth and then decreased from postnatal day 10 to adulthood. In parallel, its molecular forms shifted from the least phosphorylated to the more phosphorylated ones. This result may reflect the evolution of the activity of stathmin during development and the subsequent maturation of the brain. In conclusion, our results substantiate the likely role of stathmin as an intracellular relay of extracellular regulations, as they point out its specific importance related to neuronal functions and brain differentiation.

1-Methyl-3-isobutylxanthine↗

PubMed1988

Mu and delta opiate receptors coupled negatively to adenylate cyclase on embryonic neurons from the mouse striatum in primary cultures.

Primary cultures of pure populations of neuronal or glial cells from the striatum, the cerebral cortex, and the mesencephalon of the mouse embryo were used to look for the presence of opiate receptors coupled to adenylate cyclase. Leu-enkephalin inhibited cAMP production in membranes of embryonic striatal neurons but not in those of other cell types examined. Mu and delta opiate receptors seemed to be coupled negatively to adenylate cyclase in embryonic striatal neurons. It was found that DTLET (a selective delta agonist), as well as DAGO (a selective mu agonist), inhibited cAMP production on these cells. DTLET but not, however, DAGO produced a similar effect on homogenates from the adult rat striatum and on membranes from the neuroblastoma x glioma hybrid cell line NG 108-15, two preparations known to possess only delta receptors negatively coupled to adenylate cyclase. The selective kappa agonist U 50.488 was ineffective on all types of membrane preparations used. The inhibitory effects of both DTLET and DAGO on basal adenylate cyclase activity in striatal neurons were reversed by naloxone with a similar efficacy. Two other selective mu agonists, trimu 5 and morphiceptin, inhibited cAMP production in membranes of striatal neurons as well. The nonadditivity of the inhibitory effects of DTLET and DAGO on basal or forskolin-induced activation of adenylate cyclase suggested that mu and delta receptors were colocalized on a similar subpopulation of striatal cells in primary culture. These cells possess dopaminergic receptors of the D1 subtype as well since the amplitude of the inhibitory effects of DTLET and DAGO on cAMP production was increased in the presence of dopamine.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenylyl Cyclase Inhibitors↗

PubMed1987

Somatostatin receptors on cortical neurones and adenohypophysis: comparison between specific binding and adenylate cyclase inhibition.

Primary cultures of mouse embryonic neurones from the cerebral cortex and rat pituitary membranes were used to identify and characterize further the somatostatin receptors coupled to an adenylate cyclase and to compare these receptors with specific binding sites for a non-reducible somatostatin analog. 125I-CGP 23996 on both tissues. 125I-CGP 23996 bound specifically to a single population of sites on cortical neurones and pituitary membranes, with a high affinity (Kd = 2.76 and 1.95 nM respectively). The rank order of potency of somatostatin-(1-14) and some analogs (somatostatin-28, [D-Trp8,D-Cys14]somatostatin-(1-14), native CGP) to displace 125I-CGP 23996 from its binding sites was similar on both tissues. Furthermore this rank order was also found identical for the inhibition of adenylate cyclase activity on cortical neuronal and pituitary membranes. Finally a good correlation was found between the order of potencies of somatostatin analogs evaluated from binding experiments and adenylate cyclase assays, suggesting the presence of the same receptor observed under two different affinity states. According to the classification of somatostatin receptors by Tran and his colleagues (1985) these results support the hypothesis that SSA is the somatostatin receptor coupled with an adenylate cyclase.

Adenylyl Cyclase Inhibitors↗

PubMed1986

Two simian virus 40 (SV40)-transformed cell lines from the mouse striatum and mesencephalon presenting astrocytic characters. I. Immunological and pharmacological properties.

Dissociate cultures were initiated from embryonic rostral mesencephalic and striatal tissues dissected from the mouse brain and previously incubated with a simian virus 40 (SV40) suspension. After several weeks in culture foci of fastly dividing cells were resuspended and cloned by successive dilutions. Several clones expressing the SV40 nuclear T antigen were obtained by these procedures and two of them, one mesencephalic (F7-Mes) and one striatal (F12-Str) were screened for the expression of glial or neuronal characters. Both clones possess adenylate cyclase-linked beta 2-adrenergic receptors. They also take up and synthesize gamma-aminobutyric acid (GABA) in amounts compatible with a glial origin. As is the case for astrocytes, the uptake of GABA is inhibited by beta-alanine and rather insensitive to the presence of diaminobutyric acid (DABA), a specific inhibitor of the neuronal GABA carrier. The most convincing evidence that F7-Mes and F12-Str belong to the astrocytic lineage comes from the fact that the two cell lines synthesize glial fibrillary acidic protein (GFAP) as demonstrated by immunofluorescence and immunoblotting. In an accompanying paper we also show that these lines behave like astrocytes when considered from the point of view of neuroglial interactions.

Animals↗

PubMed1986

Do secretin and vasoactive intestinal peptide have independent receptors on striatal neurons and glial cells in primary cultures?

Vasoactive intestinal peptide (VIP) and secretin are two related peptides that activate adenylate cyclase on membranes of striatal neurons and glial cells from embryonic mouse brain grown in primary culture. On the two cell types, the maximal activation that could be induced by secretin was only 40% above basal activity, which represented less than 15% of the maximal effect obtainable with VIP. From competition experiments performed on glial cells and the neuroblastoma X glioma hybrid, NG 108-15, a cell line known to possess both VIP and secretin sensitive-adenylate cyclase, we demonstrate that secretin does not activate VIP receptors. Furthermore, secretin has an apparent high affinity (EC50 10(-8) M) for its receptors on striatal neurons and NG 108-15 whereas an apparent low affinity (EC50 7 X 10(-6) M) was found on striatal glial cells. This suggests the existence of either two distinct secretin receptors or a desensitized form.

Adenylyl Cyclases↗

PubMed1985

Modulation by monoamines of somatostatin-sensitive adenylate cyclase on neuronal and glial cells from the mouse brain in primary cultures.

Primary cultures of mouse embryonic neuronal or glial cells from the cerebral cortex, striatum, and mesencephalon were used to identify and determine the cellular localization of somatostatin receptors coupled to an adenylate cyclase. Somatostatin inhibited basal adenylate cyclase activity on neuronal but not on glial crude membranes in the three structures examined. The somatostatin-inhibitory effect on neuronal crude membranes was still observed in the presence of (-)-isoproterenol, 3,4-dihydroxyphenylethylamine (dopamine, DA), or 5-hydroxytryptamine (5-HT, serotonin) used at a concentration (10(-5) M) inducing maximal adenylate cyclase activation. In addition, in most cases biogenic amines modified the pattern of the somatostatin-inhibitory effect, triggering either an increase in the peptide apparent affinity for its receptors or an increase in the maximal reduction of adenylate cyclase activity or both. However, 5-HT did not modify the somatostatin-inhibitory response on striatal and cortical neuronal crude membranes. The changes in somatostatin-inhibitory responses were interpreted as a colocalization of the amine and the peptide receptors on subtypes of neuronal cell populations. Finally, somatostatin was shown to inhibit adenylate cyclase activity following its activation by (-)-isoproterenol on glial crude membranes of the striatum and the mesencephalon but not on those of the cerebral cortex.

Adenylyl Cyclases↗

PubMed1985

Vasoactive intestinal polypeptide receptors linked to an adenylate cyclase, and their relationship with biogenic amine- and somatostatin-sensitive adenylate cyclases on central neuronal and glial cells in primary cultures.

The presence of vasoactive intestinal polypeptide (VIP) receptors coupled to an adenylate cyclase was demonstrated on membranes of neurons or glial cells grown in primary cultures originating from the cerebral cortex, striatum, and mesencephalon of mouse embryos. A biphasic pattern of activation was observed in all these cell types, involving distinct high- and low-apparent-affinity mechanisms. The absence of additive effects of VIP and 3,4-dihydroxyphenylethylamine (DA, dopamine), isoproterenol (ISO), and 5-hydroxytryptamine (5-HT, serotonin) suggests that the peptide receptors are colocated with each of the corresponding amine receptors on neuronal membranes of the three structures studied. The nonadditivity between the VIP- and ISO-induced responses on cortical and striatal glial membranes reveals as well a colocation of VIP and beta-adrenergic-sensitive adenylate cyclases on the same cells. A subpopulation of mesencephalic glia could possess only one of the two types of receptors, as a partial additivity of the VIP and ISO responses was seen. In addition, VIP modified the characteristics of the somatostatin inhibitory effect on adenylate cyclase activity of neuronal membranes from the cerebral cortex and striatum but not from those of the mesencephalon. On striatal and mesencephalic glial membranes the somatostatin inhibitory effect was observed only in the presence of VIP. However, as previously seen with ISO, the presence of VIP did not allow the appearance of a somatostatin inhibitory response on cortical glial membranes. This suggests that cortical glia are devoid of somatostatin receptors.

Adenylyl Cyclases↗

PubMed1984

Biogenic amine-sensitive adenylate cyclases in primary culture of neuronal or glial cells from mesencephalon.

Primary cultures of virtually pure mesencephalic neurons (5 days) or glials (4 weeks) from 14-day-old mouse embryo were obtained using appropriate medium. Membranes prepared from neuronal cells contained mainly serotonin and beta 1-adrenergic-sensitive adenylate cyclases. However, a low but significant classical dopamine-sensitive adenylate cyclase activity (D1 receptor) was detected. Contrasting with the data obtained from a previous study on striatal neurons no adenosine-sensitive adenylate cyclase was found on mesencephalic neurons. Study on the additive effects of the 3 biogenic amines-sensitive adenylate cyclases indicated that: all neuronal cells having dopamine receptors possess beta 1-adrenergic receptors (no additivity); beta 1-adrenergic and serotonin receptors on the one hand, and dopamine and serotonin receptors on the other hand, were coupled with independent adenylate cyclase systems localized either on two different domains of the same cell or on different cells (complete additivity). Membranes prepared from primary mesencephalic cultures of glial cells contained a mixture of beta 1- and beta 2-adrenergic receptor subtypes coupled with an adenylate cyclase (70% and 30%, respectively). No dopamine- or serotonin-sensitive adenylate cyclase was detected on mesencephalic glial cells.

Adenylyl Cyclases↗