Dopamine-induced translocation of protein kinase C isoforms visualized in renal epithelial cells

Nowicki, Susana; Kruse, María Sol; Brismar, Hjalmar; Aperia, Anita

doi:10.1152/ajpcell.2000.279.6.c1812

Cited by 49 publications

(42 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Based on these data that show dramatic changes in actin at the apical membrane within 20 min, we postulate that the time taken to reach maximum albumin uptake is required for the de novo assembly of the actin substructure and the recruitment of the proteins required to form the endocytic complex. A similar rapid time frame has been shown for the translocation of PKC-␣ in LLC-PK 1 cells treated with dopamine (30). Treatment of OK cells with dopamine, which increases cAMP levels, leads to a rapid downregulation of NHE3 activity resulting from increased clathrinmediated endocytosis of NHE3 protein (3,17).…”

Section: Discussionsupporting

confidence: 66%

PKC-α-mediated remodeling of the actin cytoskeleton is involved in constitutive albumin uptake by proximal tubule cells

Hryciw¹,

Pollock²,

Poronnik³

2005

American Journal of Physiology-Renal Physiology

View full text Add to dashboard Cite

One key role of the renal proximal tubule is the reabsorption of proteins from the glomerular filtrate by constitutive receptor-mediated endocytosis. In the opossum kidney (OK) renal proximal tubule cell line, inhibition of protein kinase C (PKC) reduces albumin uptake, although the isoforms involved and mechanisms by which this occurs have not been identified. We used pharmacological and molecular approaches to investigate the role of PKC-α in albumin endocytosis. We found that albumin uptake in OK cells was inhibited by the pan-PKC blocker bisindolylmaleimide-1 and the isoform-specific PKC blockers Gö-6976 and 2′,3,3′,4,4′-hexahydroxy-1,1′-biphenyl-6,6′-dimethanol dimethyl ether, indicating a role for PKC-α. Overexpression of a kinase deficient PKC-α(K368R) but not wild-type PKC-α significantly reduced albumin endocytosis. Western blot analysis of fractionated cells showed an increased association of PKC-α-green fluorescent protein with the membrane fraction within 10–20 min of exposure to albumin. We used phalloidin to demonstrate that albumin induces the formation of clusters of actin at the apical surface of OK cells and that these clusters correspond to the location of albumin uptake. These clusters were not present in cells grown in the absence of albumin. In cells treated either with PKC inhibitors or overexpressing kinase-deficient PKC-α(K368R) this actin cluster formation was significantly reduced. This study identifies a role for PKC-α in constitutive albumin uptake in OK cells by mediating assembly of actin microfilaments at the apical membrane.

show abstract

Section: Discussionsupporting

confidence: 66%

PKC-α-mediated remodeling of the actin cytoskeleton is involved in constitutive albumin uptake by proximal tubule cells

Hryciw¹,

Pollock²,

Poronnik³

2005

American Journal of Physiology-Renal Physiology

View full text Add to dashboard Cite

show abstract

“…One can hypothesize that the observed reduction of cytosolic Ca 2ϩ concentrations upon glucose stimulation might result in lower ATP consumption by reticulum ATP-dependent Ca 2ϩ pumps. In addition, hyperpolarizing effects of dopamine in beta cells could diminish the activation of the sodium/ potassium ATP pump, as demonstrated in renal cells (29). All these results indicate that the increase in glucose-induced ATP generation induced by dopamine could be the consequence of reduced ATP consumption.…”

Section: Discussionmentioning

confidence: 70%

Dopamine D2-like Receptors Are Expressed in Pancreatic Beta Cells and Mediate Inhibition of Insulin Secretion

Rubı́

Ljubicic

Pournourmohammadi

et al. 2005

Journal of Biological Chemistry

227

205

View full text Add to dashboard Cite

Dopamine is a neurotransmitter that plays a critical role in neurological and psychiatric disorders, such as schizophrenia, Parkinson disease, and drug addiction (1). Increasing evidence also shows implication of dopamine in various physiological functions such as cell proliferation (2), gastrointestinal protection (3), and inhibition of prolactin secretion (4). Effects of dopamine on insulin secretion in general and on pancreatic beta cell function in particular have been poorly studied. Insulin exocytosis from the beta cell is primarily controlled by metabolismsecretion coupling. First, glucose equilibrates across the plasma membrane and is phosphorylated by glucokinase, initiating glycolysis (5). Subsequently, mitochondrial metabolism generates ATP, which promotes the closure of ATP-sensitive potassium channels and, as a consequence, depolarization of the plasma membrane (6). This leads to calcium influx through voltage-gated calcium channels and a rise in cytosolic calcium, triggering insulin exocytosis (6, 7). Additional signals participating in the amplifying pathway (8) are necessary to reproduce the sustained secretion elicited by glucose. Insulin secretion evoked by glucose metabolism can be further modulated by parasympathetic and sympathetic neurotransmitters (9).Treatment with dopamine precursor L-dopa in humans suffering from Parkinson disease reduces insulin secretion upon oral glucose tolerance test (10). In rodents, a single injection with L-dopa results in the accumulation of dopamine in beta cells and inhibition of the insulin secretory responses (11,12). In isolated islets, analogues of dopamine inhibit glucose-stimulated insulin release (13), whereas one study reports potentiation of insulin secretion upon acute dopamine accumulation (14). Taken as a whole, these previous studies suggest that beta cells might be directly responsive to dopamine. Here, we investigated the molecular mechanisms implicated in beta cell responses to dopamine action. In particular, the present data demonstrate the presence of dopamine receptors in beta cells. Moreover, the inhibitory effects of dopamine are predominantly ascribed to activation of the D2-like receptor family members. MATERIALS AND METHODS INS-1E Cells and Pancreatic Islets-INS-1Ecells, used as a well differentiated beta cell clone (15), were cultured in a humidified atmosphere containing 5% CO 2 in a medium composed of RPMI 1640 supplemented with 10 mM Hepes, 5% (v/v) heat-inactivated fetal calf serum, 2 mM glutamine, 100 units/ml penicillin, 100 g/ml streptomycin, 1 mM sodium pyruvate, and 50 M 2-mercaptoethanol. For rodent islets, Wistar rats or BALB/c mice weighing 200 -250 g and 25-30 g, respectively, were obtained from in-house breeding (CMU-Zootechnie, Geneva, Switzerland). We followed the principles of laboratory animal care, and the study was approved by the responsible ethics committee. Pancreatic islets were isolated by collagenase digestion and handpicking from male Wistar rats or BALB/c mice as described previously (16). Isolated islets w...

show abstract

“…DA translocates the enzyme so that it acts as a integral membrane protein and this, in turn, can activate pumps and/or transporting channels, as demonstrated in an experiment in proximal tubule cells. 37 In this experiment, Nowicki and Cols demonstrated that dopamine interacts with PKC, in Ca + -dependent and independent mechanisms. PKC stimulation by DA would be induced by D 1A receptors that would increase cAMP levels, thus activating PKA which, in turn, would further activate PKC.…”

Section: Pkc (Protein Kinase C)mentioning

confidence: 83%

Dopamine, hypertension and obesity

et al. 2002

View full text Add to dashboard Cite

Dopamine-induced translocation of protein kinase C isoforms visualized in renal epithelial cells

Cited by 49 publications

References 22 publications

PKC-α-mediated remodeling of the actin cytoskeleton is involved in constitutive albumin uptake by proximal tubule cells

PKC-α-mediated remodeling of the actin cytoskeleton is involved in constitutive albumin uptake by proximal tubule cells

Dopamine D2-like Receptors Are Expressed in Pancreatic Beta Cells and Mediate Inhibition of Insulin Secretion

Dopamine, hypertension and obesity

Contact Info

Product

Resources

About