Mechanical strain-enhanced fetal lung cell proliferation is mediated by phospholipase C and D and protein kinase C

1995 ◽  
Vol 268 (5) ◽  
pp. L729-L738 ◽  
Author(s):  
M. Liu ◽  
J. Xu ◽  
J. Liu ◽  
M. E. Kraw ◽  
A. K. Tanswell ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Phospholipase C ◽  
Second Messengers ◽  
Mechanical Strain ◽  
Rat Lung ◽  
Dependent Protein Kinase ◽  
Fetal Rat ◽  
Fetal Rat Lung ◽  
Dependent Protein ◽  
Pkc Activation

The signaling pathways by which intermittent strain (60 cycles/min, 15 min/h) regulates proliferation of mixed fetal rat lung cell in vitro have been investigated. Adenosine 3',5'-cyclic monophosphate (cAMP) content and cAMP-dependent protein kinase (PKA) activity were not affected by strain. The stimulatory effect of strain on DNA synthesis was also not influenced by the cyclic nucleotide-dependent protein kinase inhibitors H-8 or HA-1004, the adenylate cyclase inhibitor SQ-22536, or a PKA inhibitor and cAMP antagonist, adenosine 3',5'-cyclic monophosphothioate (Rp-cAMPS). In contrast, intracellular concentrations of two second messengers, inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG), were dramatically increased after a short period of strain. This increase in second messengers was accompanied by an increased tyrosine phosphorylation of phospholipase C-gamma 1. Phospholipase D activity was also increased by strain. Mechanical strain elicited a shift in the subcellular distribution of PKC activity from cytosol to membranes shortly after the onset of strain. The specific activity of PKC in the membranes increased 6- to 10-fold within 5-15 min and remained increased throughout a 48-h period of intermittent strain. Strain-induced PKC activation and DNA synthesis were blocked by the PKC inhibitors H-7, staurosporine, and calphostin C, as well as by the phospholipase C inhibitor U-73,122. We conclude that mechanical strain of mixed fetal rat lung cells activates phospholipid turnover via phospholipases, followed by PKC activation, which then triggers the downstream events that lead to cell proliferation.

scholarly journals Domain Swapping Used To Investigate the Mechanism of Protein Kinase B Regulation by 3-Phosphoinositide-Dependent Protein Kinase 1 and Ser473 Kinase

1999 ◽  
Vol 19 (7) ◽  
pp. 5061-5072 ◽  
Author(s):  
Mirjana Andjelković ◽  
Sauveur-Michel Maira ◽  
Peter Cron ◽  
Peter J. Parker ◽  
Brian A. Hemmings
Keyword(s):  
Protein Kinase ◽  
Kinase Inhibitors ◽  
Protein Kinase B ◽  
Second Messengers ◽  
Activation Mechanism ◽  
Dependent Protein Kinase ◽  
Dependent Protein ◽  
Phosphoinositide 3 Kinase ◽  
Regulatory Sites

ABSTRACT Protein kinase B (PKB or Akt), a downstream effector of phosphoinositide 3-kinase (PI 3-kinase), has been implicated in insulin signaling and cell survival. PKB is regulated by phosphorylation on Thr308 by 3-phosphoinositide-dependent protein kinase 1 (PDK1) and on Ser473 by an unidentified kinase. We have used chimeric molecules of PKB to define different steps in the activation mechanism. A chimera which allows inducible membrane translocation by lipid second messengers that activate in vivo protein kinase C and not PKB was created. Following membrane attachment, the PKB fusion protein was rapidly activated and phosphorylated at the two key regulatory sites, Ser473 and Thr308, in the absence of further cell stimulation. This finding indicated that both PDK1 and the Ser473 kinase may be localized at the membrane of unstimulated cells, which was confirmed for PDK1 by immunofluorescence studies. Significantly, PI 3-kinase inhibitors prevent the phosphorylation of both regulatory sites of the membrane-targeted PKB chimera. Furthermore, we show that PKB activated at the membrane was rapidly dephosphorylated following inhibition of PI 3-kinase, with Ser473 being a better substrate for protein phosphatase. Overall, the results demonstrate that PKB is stringently regulated by signaling pathways that control both phosphorylation/activation and dephosphorylation/inactivation of this pivotal protein kinase.

Signalling functions for sphingolipid long-chain bases in Saccharomyces cerevisiae

2005 ◽  
Vol 33 (5) ◽  
pp. 1170-1173 ◽  
Author(s):  
K. Liu ◽  
X. Zhang ◽  
C. Sumanasekera ◽  
R.L. Lester ◽  
R.C. Dickson
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Kinase ◽  
Second Messengers ◽  
Dependent Protein Kinase ◽  
Yeast Saccharomyces Cerevisiae ◽  
Signalling Molecules ◽  
Cellular Processes ◽  
Wide Range ◽  
Dependent Protein ◽  
Long Chain

Over the past several years, studies of sphingolipid functions in the baker's yeast Saccharomyces cerevisiae have revealed that the sphingoid LCBs (long-chain bases), dihydrosphingosine and PHS (phytosphingosine), are important signalling molecules or second messengers under heat stress and during non-stressed conditions. LCBs are now recognized as regulators of AGC-type protein kinase (where AGC stands for protein kinases A, G and C) Pkh1 and Pkh2, which are homologues of mammalian phosphoinositide-dependent protein kinase 1. LCBs were previously shown to activate Pkh1 and Pkh2, which then activate the downstream protein kinase Pkc1. We have recently demonstrated that PHS stimulates Pkh1 to activate additional downstream kinases including Ypk1, Ypk2 and Sch9. We have also found that PHS acts downstream of Pkh1 and partially activates Ypk1, Ypk2 and Sch9. These kinases control a wide range of cellular processes including growth, cell wall integrity, stress resistance, endocytosis and aging. As we learn more about the cellular processes controlled by Ypk1, Ypk2 and Sch9, we will have a far greater appreciation of LCBs as second messengers.

scholarly journals Use of phosphosynapsin I-specific antibodies for image analysis of signal transduction in single nerve terminals

2000 ◽  
Vol 113 (20) ◽  
pp. 3573-3582 ◽  
Author(s):  
A. Menegon ◽  
D.D. Dunlap ◽  
F. Castano ◽  
F. Benfenati ◽  
A.J. Czernik ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Nerve Terminal ◽  
Polyclonal Antibodies ◽  
Second Messengers ◽  
Nerve Terminals ◽  
Dependent Protein Kinase ◽  
Spatially Resolved ◽  
Dependent Protein

We have developed a semi-quantitative method for indirectly revealing variations in the concentration of second messengers (Ca(2+), cyclic AMP) in single presynaptic boutons by detecting the phosphorylation of the synapsins, excellent nerve terminal substrates for cyclic AMP- and Ca(2+)/calmodulin-dependent protein kinases. For this purpose, we employed polyclonal, antipeptide antibodies recognising exclusively synapsin I phosphorylated by Ca(2+)/calmodulin-dependent protein kinase II (at site 3) or synapsins I/II phosphorylated by either cAMP-dependent protein kinase or Ca(2+)/calmodulin-dependent protein kinase I (at site 1). Cerebellar granular neurones in culture were double-labelled with a monoclonal antibody to synapsins I/II and either of the polyclonal antibodies. Digitised images were analysed to determine the relative phosphorylation stoichiometry at each individual nerve terminal. We have found that: (i) under basal conditions, phosphorylation of site 3 was undetectable, whereas site 1 exhibited some degree of constitutive phosphorylation; (ii) depolarisation in the presence of extracellular Ca(2+) was followed by a selective and widespread increase in site 3 phosphorylation, although the relative phosphorylation stoichiometry varied among individual terminals; and (iii) phosphorylation of site 1 was increased by stimulation of cyclic AMP-dependent protein kinase but not by depolarisation and often occurred in specific nerve terminal sub-populations aligned along axon branches. In addition to shedding light on the regulation of synapsin phosphorylation in living nerve terminals, this approach permits the spatially-resolved analysis of the activation of signal transduction pathways in the presynaptic compartment, which is usually too small to be studied with other currently available techniques.

An Essential Function of a Phosphoinositide-Specific Phospholipase C Is Relieved by Inhibition of a Cyclin-Dependent Protein Kinase in the Yeast Saccharomyces cerevisiae

Genetics ◽  
1998 ◽  
Vol 148 (1) ◽  
pp. 33-47 ◽  
Author(s):  
Jeffrey S Flick ◽  
Jeremy Thorner
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Kinase ◽  
Phospholipase C ◽  
Growth Defect ◽  
Temperature Sensitive ◽  
Complete Medium ◽  
Restrictive Temperature ◽  
Dependent Protein Kinase ◽  
Yeast Saccharomyces Cerevisiae ◽  
Dependent Protein

Abstract The PLC1 gene product of Saccharomyces cerevisiae is a homolog of the δ isoform of mammalian phosphoinositide-specific phospholipase C (PI-PLC). We found that two genes (SPL1 and SPL2), when overexpressed, can bypass the temperature-sensitive growth defect of a plc1Δ cell. SPL1 is identical to the PHO81 gene, which encodes an inhibitor of a cyclin (Pho80p)-dependent protein kinase (Pho85p) complex (Cdk). In addition to overproduction of Pho81p, two other conditions that inactivate this Cdk, a cyclin (pho80Δ) mutation and growth on low-phosphate medium, also permitted growth of plc1Δ cells at the restrictive temperature. Suppression of the temperature sensitivity of plc1Δ cells by pho80Δ does not depend upon the Pho4p transcriptional regulator, the only known substrate of the Pho80p/Pho85p Cdk. The second suppressor, SPL2, encodes a small (17-kD) protein that bears similarity to the ankyrin repeat regions present in Pho81p and in other known Cdk inhibitors. Both pho81Δ and spl2Δ show a synthetic phenotype in combination with plc1Δ. Unlike single mutants, plc1Δ pho81Δ and plc1Δ spl2Δ double mutants were unable to grow on synthetic complete medium, but were able to grow on rich medium.

scholarly journals Hormone-induced protein phosphorylation. III. regulation of the phosphorylation of the secretagogue-responsive 29,000-dalton protein by both Ca2+ and cAMP in vitro.

1982 ◽  
Vol 95 (3) ◽  
pp. 918-923 ◽  
Author(s):  
S D Freedman ◽  
J D Jamieson
Keyword(s):  
Protein Kinase ◽  
Protein Phosphorylation ◽  
Exocrine Pancreas ◽  
Second Messengers ◽  
Subcellular Fractions ◽  
Protein Kinase Activity ◽  
Dependent Protein Kinase ◽  
Intact Cells ◽  
Dependent Protein

In the preceding papers, we demonstrated that the endogenous phosphorylation of a 29,000-dalton protein is stimulated in response to secretagogue application to intact cells from the rat exocrine pancreas and parotid and dephosphorylated upon termination of secretagogue action. One- and two-dimensional gel analysis of 32Pi-labeled pancreatic and parotid lobules as well as their respective subcellular fractions revealed that the same protein was covalently modified in both tissues and was localized to the ribosomal fraction. To identify the intracellular second messengers which may mediate or modulate the phosphorylation of the 29,000-dalton protein in intact cells, the effects of Ca2+, cAMP, and cGMP on the endogenous phosphorylation of this protein were assessed in subcellular fractions from the rat pancreas and parotid. Our results demonstrate that the phosphorylation of the 29,000-dalton polypeptide may be regulated by both Ca2+ and cAMP in the pancreas and in the parotid. No cGMP-dependent protein phosphorylation was found in either tissue. As in the in situ phosphorylation studies, the Ca2+- and cAMP-dependent phosphorylation of this same protein was localized to the ribosomal fraction. The cAMP-dependent protein kinase activity was found primarily in the postmicrosomal supernatant in contrast to the Ca2+-dependent protein kinase that appeared to be tightly associated with the substrate in addition to being present in the postmicrosomal supernatant. The data suggest that, in cells from the exocrine pancreas and parotid, secretagogues may regulate the phosphorylation of the 29,000-dalton protein through Ca2+ and/or cAMP.

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