Developmental Changes in Mitochondrial Components in Liver of Newborn Rats

Miyahara, Masanobu; Kitazoe, Yasuhiro; Hiraoka, Nobuaki; Takeda, Koji; Watanabe, Sadahiro; Sasaki, Junzo; Okimasu, Eiji; Osaki, Yumi; Yamamoto, Hiroto; Utsumi, Kozo

doi:10.1159/000241887

Cited by 6 publications

(1 citation statement)

References 14 publications

(22 reference statements)

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“…The fact that CL transacylase activity was low compared with MLCL-AT activity coupled with an observed increase in MLCL-AT activity and protein expression in PHx animals could explain why there was an increase in [1- 14 C]linoleate incorporation into CL in the hepatocyte radiolabelling experiments. The content of CL was shown to double during normal liver growth from birth to adulthood in the rat and the fatty acid composition was altered, with a net enrichment of 18:2 [39,40]. In addition, the fatty acid composition of CL was not changed in whole liver preparations from rats undergoing liver regeneration [32].…”

Section: Discussionmentioning

confidence: 99%

On the mechanism of the increase in cardiolipin biosynthesis and resynthesis in hepatocytes during rat liver regeneration

Webster

Jiang

Lü

et al. 2005

Biochemical Journal

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CL (cardiolipin) is a major mitochondrial membrane phospholipid important for the regulation of mitochondrial function. We examined CL de novo biosynthesis and its resynthesis in isolated rat liver hepatocytes prepared 48 h subsequent to two-thirds PHx (partial hepatectomy). The pool size of CL and its de novo biosynthesis from [1,3-(3)H]glycerol were increased 3.3-fold (P<0.05) and 3.1-fold (P<0.05) respectively in hepatocytes prepared from PHx rats compared with sham-operated controls. The reason for the increased CL biosynthesis was a 65% increase (P<0.05) in enzymic activity in PGP-S (phosphatidylglycerolphosphate synthase), a key enzyme in de novo CL biosynthesis. The increase in PGP-S activity was due to a 3-fold increase (P<0.05) of hepatic PGP-S mRNA expression. The increase in de novo CL biosynthesis and pool size corresponded to a 2.3-fold increase (P<0.05) in the amount of [1-14C]linoleic acid incorporated into CL of hepatocytes prepared from PHx rats compared with sham-operated controls, indicating an increase in CL resynthesis. The activity of MLCL-AT (monolysocardiolipin acyltransferase), a rate-limiting enzyme of CL resynthesis, was increased by 43% (P<0.05) in hepatocytes prepared from PHx rats compared with sham-operated controls; this result would explain the increase in [1-14C]linoleic acid incorporation into CL. The increase in MLCL-AT activity was due to an increase in hepatic MLCL-AT protein expression. The results show that CL de novo biosynthesis and its resynthesis are increased during liver regeneration.

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Section: Discussionmentioning

confidence: 99%

On the mechanism of the increase in cardiolipin biosynthesis and resynthesis in hepatocytes during rat liver regeneration

Webster

Jiang

Lü

et al. 2005

Biochemical Journal

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Lipids and thyroid hormones

Hoch

1988

Progress in Lipid Research

144

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Cardiolipins and biomembrane function

Hoch

1992

Biochimica et Biophysica Acta (BBA) - Reviews on Biomembranes

570

373

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Evidence is discussed for roles of cardiolipins in oxidative phosphorylation mechanisms that regulate State 4 respiration by returning ejected protons across and over bacterial and mitochondrial membrane phospholipids, and that regulate State 3 respiration through the relative contributions of proteins that transport protons, electrons and/or metabolites. The barrier properties of phospholipid bilayers support and regulate the slow proton leak that is the basis for State 4 respiration. Proton permeability is in the range 10(-3)-10(-4) cm s-1 in mitochondria and in protein-free membranes formed from extracted mitochondrial phospholipids or from stable synthetic phosphatidylcholines or phosphatidylethanolamines. The roles of cardiolipins in proton conductance in model phospholipid membrane systems need to be assessed in view of new findings by Hübner et al. [313]: saturated cardiolipins form bilayers whilst natural highly unsaturated cardiolipins form nonlamellar phases. Mitochondrial cardiolipins apparently participate in bilayers formed by phosphatidylcholines and phosphatidylethanolamines. It is not yet clear if cardiolipins themselves conduct protons back across the membrane according to their degree of fatty acyl saturation, and/or modulate proton conductance by phosphatidylcholines and phosphatidylethanolamines. Mitochondrial cardiolipins, especially those with high 18:2 acyl contents, strongly bind many carrier and enzyme proteins that are involved in oxidative phosphorylation, some of which contribute to regulation of State 3 respiration. The role of cardiolipins in biomembrane protein function has been examined by measuring retained phospholipids and phospholipid binding in purified proteins, and by reconstituting delipidated proteins. The reconstitution criterion for the significance of cardiolipin-protein interactions has been catalytical activity; proton-pumping and multiprotein interactions have yet to be correlated. Some proteins, e.g., cytochrome c oxidase are catalytically active when dimyristoylphosphatidylcholine replaces retained cardiolipins. Cardiolipin-protein interactions orient membrane proteins, matrix proteins, and on the outerface receptors, enzymes, and some leader peptides for import; activate enzymes or keep them inactive unless the inner membrane is disrupted; and modulate formation of nonbilayer HII-phases. The capacity of the proton-exchanging uncoupling protein to accelerate thermogenic respiration in brown adipose tissue mitochondria of cold-adapted animals is not apparently affected by the increased cardiolipin unsaturation; this protein seems to take over the protonophoric role of cardiolipins in other mitochondria. Many in vivo influences that affect proton leakage and carrier rates selectively alter cardiolipins in amount per mitochondrial phospholipids, in fatty acyl composition and perhaps in sidedness; other mitochondrial membrane phospholipids respond less or not at all.(ABSTRACT TRUNCATED AT 400 WORDS)

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Developmental Changes in Mitochondrial Components in Liver of Newborn Rats

Cited by 6 publications

References 14 publications

On the mechanism of the increase in cardiolipin biosynthesis and resynthesis in hepatocytes during rat liver regeneration

On the mechanism of the increase in cardiolipin biosynthesis and resynthesis in hepatocytes during rat liver regeneration

Lipids and thyroid hormones

Cardiolipins and biomembrane function

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