Generation and remodeling of phospholipid molecular species in rat hepatocytes.
In order to assess the relationship between de novo phospholipid synthesis and remodeling by deacylation-reacylation, we have pulse-labeled glycerolipids by incubating rat hepatocytes in media containing either [U-14C]glycerol or H218O. Further incubation for up to 2 h in the absence of the labeled substrates and analysis of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) provided information on the remodeling of newly synthesized molecular species by deacylation-reacylation at the sn-1 or sn-2 positions of glycerol. We conclude that de novo synthesis of PC and PE yields primarily four molecular species: 16:0-18:2 (n-6), 16:0-18:1, 16:0-22:6 (n-3), and 18:1-18:2 (n-6). Remodeling occurs in both lipid classes by replacement of the fatty acids at the sn-1 position with stearic acid, 18:0, or at the sn-2 position with arachidonic acid, 20:4 (n-6). A major molecular species of both PC and PE, 18:0-20:4 (n-6), appears to be produced by deacylation-reacylation at both the sn-1 and sn-2 positions and not to be further remodeled. De novo synthesis and remodeling of PC and PE in rat hepatocytes occur at similar rates, involve precursor-product relationships among newly synthesized molecular species, and therefore may be regulated as a single metabolic process.
Schmid
P C
PC
Hormel Institute, University of Minnesota, Austin 55912, USA.
Deli
E
E
Schmid
H H
HH
D000215:Acylation; D000818:Animals; D002250:Carbon Radioisotopes; D005990:Glycerol / Q000378:metabolism; D066298:In Vitro Techniques; D008099:Liver / Q000378:metabolism*; D008297:Male; D010103:Oxygen Isotopes; D010713:Phosphatidylcholines / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D010714:Phosphatidylethanolamines / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D010743:Phospholipids / Q000096:biosynthesis* / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014867:Water / Q000378:metabolism
D002250:Carbon Radioisotopes; D010103:Oxygen Isotopes; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010743:Phospholipids; D014867:Water; D005990:Glycerol