Neomycin reversibly disrupts mitotic progression in stamen hair cells of Tradescantia

1991 ◽  
Vol 98 (2) ◽  
pp. 159-168
Author(s):  
PAUL M. LARSEN ◽  
TUNG-LING L. CHEN ◽  
STEPHEN M. WOLNIAK
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Hair Cells ◽  
Inhibitory Effect ◽  
Mitotic Progression ◽  
Metaphase Arrest ◽  
Nuclear Envelope Breakdown ◽  
Regulatory Cascade ◽  
Kinase C ◽  
Inositol 1,4,5 Trisphosphate

Neomycin has been reported to inhibit polyphosphoinositide cycling by preventing the hydrolysis of phosphatidylinositol 4,5-bisphosphate into inositol 1,4,5-trisphosphate and 1,2-diacylglycerol. Inositol 1,4,5-trisphosphate, through the mobilization of calcium, and 1,2-diacylglycerol, through the activation of protein kinase C, trigger many physiological responses. The addition of 2 mM neomycin to stamen hair cells of Tradescantia virginiana at various points during mitosis arrests cells in prophase, prior to nuclear envelope breakdown, or in metaphase. Arrest in prophase is irreversible. Metaphase arrest can persist for over 2h before the cells attempt to revert to interphase without dividing. Entry into anaphase by the majority of cells in our sample arrested in metaphse occurred after treatment with 1,2-dioctanoylglycerol while 1,3-dioctanoylglycerol was totally ineffective at reversal. Perfusion of 100 μM calcium chloride solution past the cells was sufficient to reverse arrest in approximately half of the cells in the sample. Magnesium could not be substituted for calcium in the reversal. Clindamycin, another member of this class of aminoglycoside antibiotics, with no known inhibitory effect on polyphosphoinositide cycling, is without effect on mitotic progression in stamen hair cells. Our results indirectly implicate one or more episodes of polyphosphoinositide cycling and its resultant protein phosphorylation by protein kinase C in the regulatory cascade that leads to anaphase.

Inhibitory Effect of Barbiturates and Local Anaesthetics on Protein Kinase C Activation

1990 ◽  
Vol 18 (2) ◽  
pp. 153-160 ◽  
Author(s):  
K. Mikawa ◽  
N. Maekawa ◽  
H. Hoshina ◽  
O. Tanaka ◽  
J. Shirakawa ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Local Anaesthetics ◽  
Inhibitory Effect ◽  
Kinase C ◽  
Protein Kinase C Activation

Inhibitory Effect of Hypocrellin A on Protein Kinase C in Liver and Skeletal Muscle of Obese Zucker Rats

2003 ◽  
Vol 31 (06) ◽  
pp. 871-878 ◽  
Author(s):  
Xianqin Qu ◽  
Lei Dang ◽  
J. Paul Seale
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Inhibitory Effect ◽  
Zucker Rats ◽  
Dependent Manner ◽  
Kinase C ◽  
Hypocrellin A ◽  
Pkc Isoforms ◽  
Obese Zucker Rats

In this ex vivo study, the inhibitory activity of hypocrellin A (HA), a perylene quinonoid pigment isolated from the Chinese medicinal fungus Hypocrella bambuase, on protein kinase C (PKC) enzyme activity in insulin target tissues of obese Zucker rats was assessed. Pre-incubation with HA for 30 minutes significantly inhibited the activity of partially purified PKC enzyme from liver and soleus skeletal muscle in a dose-dependent manner ( IC 50=0.07 and 0.26 μg/ml, respectively). HA produced a greater inhibitory effect in enzyme prepared from the liver than enzyme prepared from soleus muscle. Since total PKC activity in these two insulin target tissues is the net result of several different isoforms of PKC, and PKC-θ is a major isoform expressed in the soleus skeletal muscle, the present data suggest that the naturally occurring compound, HA, may selectively inhibit certain PKC isoforms other than PKC-θ. Further investigations are required to determine which PKC isoforms are most susceptible to HA and whether changes in PKC signaling during treatment with HA can reverse abnormalities of glucose and lipid metabolism in insulin resistant and diabetic states.

scholarly journals Protein kinase C in rod outer segments: effects of phosphorylation of the phosphodiesterase inhibitory subunit

1996 ◽  
Vol 317 (1) ◽  
pp. 291-295 ◽  
Author(s):  
Igor P. UDOVICHENKO ◽  
Jess CUNNICK ◽  
Karen GONZALEZ ◽  
Alexander YAKHNIN ◽  
Dolores J. TAKEMOTO
Keyword(s):  
Protein Kinase C ◽  
Catalytic Activity ◽  
Protein Kinase ◽  
Direct Interaction ◽  
Inhibitory Effect ◽  
Rod Outer Segments ◽  
Visual Transduction ◽  
Gtp Hydrolysis ◽  
Outer Segments ◽  
Kinase C

The inhibitory subunit (PDEγ) of the cGMP phosphodiesterase (PDEαβγ2) in rod outer segments (ROS) realizes its regulatory role in phototransduction by inhibition of PDEαβ catalytic activity. The photoreceptor G-protein, transducin, serves as a transducer from the receptor (rhodopsin) to the effector (PDE) and eliminates the inhibitory effect of PDEγ by direct interaction with PDEγ. Our previous study [Udovichenko, Cunnick, Gonzalez and Takemoto (1994) J. Biol. Chem. 269, 9850–9856] has shown that PDEγ is a substrate for protein kinase C (PKC) from ROS and that phosphorylation by PKC increases the ability of PDEγ to inhibit PDEαβ catalytic activity. Here we report that transducin is less effective in activation of PDEαβ(γp)2 (a complex of PDEαβ with phosphorylated PDEγ, PDEγp) than PDEαβγ2. PDEγp also increases the rate constant of GTP hydrolysis of transducin (from 0.16 s-1 for non-phosphorylated PDEγ to 0.21 s-1 for PDEγp). These data suggest that phosphorylation of the inhibitory subunit of PDE by PKC may regulate the visual transduction cascade by decreasing the photoresponse.

Autoregulation of muscarinic and gastrin receptors on gastric parietal cells

1989 ◽  
Vol 256 (2) ◽  
pp. G356-G363 ◽  
Author(s):  
T. Chiba ◽  
S. K. Fisher ◽  
B. W. Agranoff ◽  
T. Yamada
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Parietal Cell ◽  
Phorbol Esters ◽  
Cell Function ◽  
Inhibitory Effect ◽  
Parietal Cells ◽  
Kinase C ◽  
Protein Kinase C Activity ◽  
Inositol Phospholipids

In previous studies we demonstrated that parietal cell stimulation with gastrin and carbamoylcholine (carbachol) is accompanied by increased turnover of membrane inositol phospholipids. We conducted the present studies to examine whether membrane-associated protein kinase C activity is enhanced as a consequence of these events and to explore the role of this enzyme in regulating parietal cell function. We observed that carbachol and gastrin dose dependently increased membrane-associated protein kinase C activity while histamine did not. Furthermore, compounds such as phorbol esters and diacylglycerol, which are known to be direct stimulants of protein kinase C activity, also stimulated parietal cell aminopyrine uptake. In contrast, the phorbol ester 12-O-tetradecanoylphorbol-13-acetate and the synthetic diacylglycerol 1-oleoyl-2-acetyl-sn-glycerol inhibited both aminopyrine uptake and membrane inositol phospholipid turnover in parietal cells induced by carbachol and gastrin. The inhibitory effect appeared to result from reduction in the quantity of muscarinic and gastrin receptors without alterations in their specific affinities. These data suggest that protein kinase C mediates stimulation of parietal cells by gastrin and carbachol but also activates an autoregulatory mechanism via downregulation of muscarinic and gastrin receptors.

Caerulein-induced NF-κB/Rel activation requires both Ca2+ and protein kinase C as messengers

1999 ◽  
Vol 277 (3) ◽  
pp. G678-G686 ◽  
Author(s):  
Yusuke Tando ◽  
Hana Algül ◽  
Martin Wagner ◽  
Hans Weidenbach ◽  
Guido Adler ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Nuclear Translocation ◽  
Inhibitory Effect ◽  
Binding Activity ◽  
Atpase Inhibitor ◽  
Kinase C ◽  
Protein Kinase C Activity ◽  
Intracellular Ca ◽  
Iκbα Degradation

The eukaryotic transcription factor NF-κB/Rel is activated by a large variety of stimuli. We have recently shown that NF-κB/Rel is induced during the course of caerulein pancreatitis. Here, we show that activation of NF-κB/Rel by caerulein, a CCK analog, requires increasing intracellular Ca2+ levels and protein kinase C activation. Caerulein induces a dose-dependent increase of nuclear NF-κB/Rel binding activity in pancreatic lobules, which is paralleled by degradation of IκBα. IκBβ was only slightly affected by caerulein treatment. Consistent with an involvement of Ca2+, the endoplasmic reticulum-resident Ca2+-ATPase inhibitor thapsigargin activated NF-κB/Rel in pancreatic lobules. The intracellular Ca2+ chelator TMB-8 prevented IκBα degradation and subsequent nuclear translocation of NF-κB/Rel induced by caerulein. BAPTA-AM was less effective. Cyclosporin A, a Ca2+/calmodulin-dependent protein phosphatase (PP2B) inhibitor, decreased caerulein-induced NF-κB/Rel activation and IκBα degradation. The inhibitory effect of bisindolylmaleimide suggests that protein kinase C activity is also required for caerulein-induced NF-κB/Rel activation. These data suggest that Ca2+- as well as protein kinase C-dependent mechanisms are required for caerulein-induced NF-κB/Rel activation.

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