Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Query: EC:2.7.11.17 (
CaMKII
)
4,029
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
Using SK-N-SH cells, we observe that muscarinic acetylcholine receptor activation by methacholine (MCh) rapidly and selectively diminishes l-NE transport capacity (Vmax) with little or no change in norepinephrine (NE) Km and without apparent effects on membrane potential monitored directly under current clamp. Over the same time frame, MCh exposure reduces the density of [3H]nisoxetine binding sites (Bmax) in intact cells but not in total membrane fractions, consistent with a loss of transport capacity mediated by sequestration of transporters rather than changes in intrinsic transport activity or protein degradation. Similar changes in NE transport and [3H]nisoxetine binding capacity are observed after phorbol ester (beta-PMA) treatment. Inhibition of PKC by antagonists and downregulation of PKC by chronic treatment with phorbol esters abolishes beta-PMA-mediated effects but produce only a partial blockade of MCh-induced effects. Neither muscarinic acetylcholine receptor nor PKC activation require extracellular Ca++ to diminish
NET
activity. In contrast, treatment of cells with the Ca++/ATPase antagonist, thapsigargin in Ca++-free medium, eliminates the staurosporine-insensitive component of MCh regulation. These findings were further corroborated by the ability of [1, 2-bis(o-amino-phenoxy)ethane-N,N,N',N'-tetraacetic acid tetra(acetoxymethyl)ester application in Ca++-free medium to abolish
NET
regulation by MCh. Although they may contribute to basal
NET
expression, we could not implicate
CaMKII
-, PKA- or nitric oxide-linked pathways in MCh regulation. Together, these findings 1) provide evidence in support of G-protein coupled receptor-mediated regulation of catecholamine transport, 2) reveal intracellular Ca++-sensitive, PKC-dependent and -independent pathways that serve to regulate
NET
expression and 3) indicate that the diminished capacity for NE transport evident after mAChR and PKC activation involves a redistribution of
NET
protein.
...
PMID:Acute regulation of norepinephrine transport: I. protein kinase C-linked muscarinic receptors influence transport capacity and transporter density in SK-N-SH cells. 980 4
The antidepressant-sensitive norepinephrine (NE) transporter (
NET
) inactivates NE released during central and peripheral neuronal activity by transport into presynaptic cells. Altered NE clearance due to dysfunction of
NET
has been associated with the development of mental illness and cardiovascular diseases.
NET
activity in vivo is influenced by stress, neuronal activity, hormones and drugs. We investigated the mechanisms of Ca
2+
regulation of
NET
and found that Ca
2+
influenced both V
max
and K
m
for NE transport into cortical synaptosomes. Changes in extracellular Ca
2+
triggered rapid and bidirectional surface trafficking of
NET
expressed in cultured cells. Deletion of residues 28-47 in the
NET
NH
2
-terminus abolished the Ca
2+
effect on surface trafficking. Mutagenesis studies identified Thr30 in this region as the essential residue for both Ca
2+
- dependent phosphorylation and trafficking of
NET
. Depolarization of excitable cells increased surface
NET
in a Thr30 dependent manner. A proteomic analysis, RNA interference, and pharmacological inhibition supported roles of
CaMKI
and
CaMKII
in Ca
2+
-modulated NE transport and
NET
trafficking. Depolarization of primary noradrenergic neurons in culture with elevated K
+
increased
NET
surface expression in a process that required external Ca
2+
and depended on CaMK activity. Hippocampal NE clearance in vivo was also stimulated by depolarization, and inhibitors of CaMK signaling prevented this stimulation. In summary, Ca
2+
signaling influenced surface trafficking of
NET
through a CaMK-dependent mechanism requiring Thr30.
...
PMID:Ca
2+
dependent surface trafficking of norepinephrine transporters depends on threonine 30 and Ca
2+
calmodulin kinases. 2801 3
