Microtubule depolymerization modifies the incorporation of fatty acids into glycerolipids.
BACKGROUND
The influence of cytoskeletal integrity on fatty-acid (FA) metabolism is an almost unexplored field of biochemical research. This study therefore investigated the influence of cytoskeletal integrity on the incorporation of palmitate and eicosa-8,11,14-trienoate into glycerolipids of Hep G2 human hepatoma cells.


METHODS
Attached cultures and suspended cells were exposed to colchicine (COL, 10 microM) or dihydrocytochalasin B (DHCB, 20 microM) and supplemented with [14C]FAs bound to delipidated BSA or [14C]glycerol during 0-300 min of incubation. Various key enzymes of lipid metabolism were also determined after COL or DHCB treatment.


RESULTS
Incorporation of both FAs into phospholipids (PLs) was strongly reduced by COL treatment especially in the PE and PC subfractions at short incubation times and in PS and SM for 300 min. COL also produced increased incorporation of both FAs into neutral lipids (NL), especially in TG and its precursors (MG and DG). DHCB increased the labeling into lyso-PL and reduced incorporation into PE and SM. However, this drug did not modify the [14C]NL to [14C]PL ratio. DG-acyltransferase and phosphatidate phosphohydrolase were stimulated by COL treatment. Phospholipase A2 activity was reduced significantly by COL and stimulated by DHCB treatment.


CONCLUSIONS
It was demonstrated that the microtubule and microfilament network is involved in the incorporation of FAs and in its channeling to neutral lipids and phospholipids. These effects had differential characteristics depending on the type of FA involved and may have potential significance in the understanding of physiological and/or pathological processes.
Marra
Carlos A
CA
INIBIOLP, CONICET-UNLP, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina. camarra@atlas.med.unlp.edu.ar
de Alaniz
María J T
MJ
D045744:Cell Line, Tumor; D003078:Colchicine / Q000494:pharmacology; D003571:Cytochalasin B / Q000031:analogs & derivatives / Q000494:pharmacology; D005227:Fatty Acids / Q000378:metabolism*; D005989:Glycerides / Q000378:metabolism*; D005990:Glycerol / Q000378:metabolism; D006801:Humans; D008870:Microtubules / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism; D013997:Time Factors
D005227:Fatty Acids; D005989:Glycerides; D010743:Phospholipids; C024794:dihydrocytochalasin B; D003571:Cytochalasin B; D005990:Glycerol; D003078:Colchicine