3 research outputs found
Phospholipid metabolism and protein kinase C mediated protein phosphorylation in dietary protein deficiency in rat lung
606-613Nutritional deprivation of proteins
decreases the protein kinase C (PKC) activity in rat lung. The activity of
(PKC) is influenced by lipid metabolism. Changes in PKC activity may influence
phosphorylation of its substrate proteins in the tissues. Therefore, alterations
in phospholipid metabolism and PKC mediated protein phosphorylation in dietary
protein
deficiency in rat lung were envisaged.
The study was conducted on rats fed on three different types of diet viz .. casein
(20% protein), deficient (4% protein, rice flour as source of protein) and
supplemented (deficient diet supplemented with L-Iysine and DL-threoning). Feeding
of protein deficient diet caused reduction in incorporation of [3H] myo-inositol
in the total
phosphoinositides in lungs and an increase
in total inositol phosphate pool. There was a significant reduction in the
contents and turnover rate of phosphatidyl inositol and phosphatidyl inositol monophosphate.
Supplementation of diet with L-Iysine and DL-threonine had a reversing effect
on total pool of phosphoinositides and, the metabolism of phosphatidyl inositol
bisphosphate and phosphatidyl inositol. In phosphatidyl choline metabolism, the
dietary protein deficiency led to a decrease in incorporation of [14C-methyl]
choline-chloride in total phospholipids. In contrast, its incorporation
increased in
phosphatidyl choline pool. The contents
of phosphatidyl choline and residue, incorporation of [14C-methyl]
choline-chloride in them and their turnover rate also increased. Supplementation
of diet had a reversal effect on most of these parameters. Phosphorylation of
proteins of 84,47,35 and 16 kDa was identified to be mediated by PKC. In
dietary protein deficiency, phosphorylation of all these proteins, except that
of 47 kDa, increased. Supplementation of diet reversed the pattern except that of
84 kDa. The findings suggest that changes in phospholipid metabolism in dietary
protein deficiency may effect the activity of PKC thereby influencing the
phosphorylation of its substrate proteins and hence associated functions that
may lead to pathophysiology of lung
Effect of feeding protein deficient diet on phospholipid turnover and protein kinase C mediated protein phosphorylation in rat brain
323-331Feeding of protein deficient diet is known
to alter the transmembrane signalling in brain of rat by reducing total protein
kinase C (PKC) activity. Phospholipid metabolism regulates the activation of
PKC through generation of second messengers and the extent of PKC activation accordingly
influences the magnitude of phosphorylation of its endogenous substrate
proteins.Thus it was speculated that ingestion
of protein deficient diet may modify the turnover rate of membrane phospholipids
and magnitude of phosphorylation of endogenous substrate proteins of PKC. The
experiments were conducted on rats fed on three different types of laboratory prepared
diets viz. casein (20% casein), deficient (4% protein, rice flour as source of
protein ) and supplemented (deficient diet supplemented with L-lysine and DL-threonine)
for 28 days. The metabolism of phosphoinositides (PIs) and phosphatidyl choline
(PC) was studied by equilibrium labeling with [3H] myo inositol
and [14C methyl] choline chloride respectively. The phosphorylation
of endogenous substrate proteins of PKC was studied by using 32P-γ-ATP
followed by SDS-PAGE and autoradiography. The results suggest that in deficient
group, there is an increased incorporation of [3H] myo inositol
in PIs and inositol phosphate pool in comparison to the casein group. The phosphatidyl
inositol (PI) turnover reduced, although there was a marginal increase in the
phosphatidyl inositol monophosphate (PIP) and phosphatidyl inositol bis phosphate
(PIP2). Supplementation of diet showed a reversal of the pattern towards
control to a considerable extent. In the deficient group, PC metabolism showed
an increased incorporation of [14C methyl] choline in choline
phospholipids but decreased incorporation in phosphoryl choline in comaprison
with the casein group. The increase in total PC contents was significant but marginal
in residue contents. The turnover rate of PC increased only marginally and that
of residue declined. Supplementation of diet reduced the total contents of PC
and residue, but the turnover rate of PC and residue remained still higher.
Phosphorylation of endogenous proteins showed four different proteins of 78,
46, 33 and 16 kDa to be the substrates of PKC in casein group. In deficient group,
phosphorylation of these proteins increased markedly while supplementation of diet
had a reversing effect rendering the values to be intermediate between casein and
the supplemented group. The changes in phospholipid metabolism and in phosphorylation
of endogenous substrate proteins of PKC suggest that dietary protein deficiency
causes alterations in transmembrane signalling mechanism in rat brain. These effects
are partially reversed by improving the quality of proteins in the diet
Effect of feeding protein deficient diet on phospholipid turnover and protein kinase C mediated protein phosphorylation in rat brain
Feeding of protein deficient diet is known to alter the transmembrane signalling in brain of rat by reducing total protein kinase C (PKC) activity. Phospholipid metabolism regulates the activation of PKC through generation of second messengers and the extent of PKC activation accordingly influences the magnitude of phosphorylation of its endogenous substrate proteins. Thus it was speculated that ingestion of protein deficient diet may modify the turnover rate of membrane phospholipids and magnitude of phosphorylation of endogenous substrate proteins of PKC. The experiments were conducted on rats fed on three different types of laboratory prepared diets viz. casein (20% casein), deficient (4% protein, rice flour as source of protein) and supplemented (deficient diet supplemented with L-lysine and DL-threonine) for 28 days. The metabolism of phosphoinositides (PIs) and phosphatidyl choline (PC) was studied by equilibrium labeling with [3H] myo inositol and [14C methyl] choline chloride respectively. The phosphorylation of endogenous substrate proteins of PKC was studied by using 32P-γ-ATP followed by SDS-PAGE and autoradiography. The results suggest that in deficient group, there is an increased incorporation of [3H] myo inositol in PIs and inositol phosphate pool in comparison to the casein group. The phosphatidyl inositol (PI) turnover reduced, although there was a marginal increase in the phosphatidyl inositol monophosphate (PIP) and phosphatidyl inositol bis phosphate (PIP2). Supplementation of diet showed a reversal of the pattern towards control to a considerable extent. In the deficient group, PC metabolism showed an increased incorporation of [14C methyl] choline in choline phospholipids but decreased incorporation in phosphoryl choline in comparison with the casein group. The increase in total PC contents was significant but marginal in residue contents. The turnover rate of PC increased only marginally and that of residue declined. Supplementation of diet reduced the total contents of PC and residue, but the turnover rate of PC and residue remained still higher. Phosphorylation of endogenous proteins showed four different proteins of 78, 46, 33 and 16 kDa to be the substrates of PKC in casein group. In deficient group, phosphorylation of these proteins increased markedly while supplementation of diet had a reversing effect rendering the values to be intermediate between casein and the supplemented group. The changes in phospholipid metabolism and in phosphorylation of endogenous substrate proteins of PKC suggest that dietary protein deficiency causes alterations in transmembrane signalling mechanism in rat brain. These effects are partially reversed by improving the quality of proteins in the diet