INVESTIGADORES
QUIROGA Ariel Dario
congresos y reuniones científicas
Título:
Energy Demand of the Cell Determines the Lipid Droplet Proteome in the Mouse Liver
Autor/es:
QUIROGA, ARIEL DARIO; KRAMER, DAVID; FAHLMAN, RICHARD; LEHNER, RICHARD
Reunión:
Conferencia; Canadian Lipoprotein Conference; 2012
Resumen:
Energy Demand of the Cell Determines the Lipid
Droplet Proteome in the Mouse Liver
Ariel D.
Quiroga1,2, David Kramer3, Richard Fahlman3, and
Richard Lehner1,2,4
1Department of Pediatrics, University of
Alberta, Edmonton, AB, Canada
2Group on Molecular and Cell Biology of
Lipids, University of Alberta, Edmonton, AB, Canada
3Department of Biochemistry, University of
Alberta, Edmonton, AB, Canada
4Department of Cell Biology, University of
Alberta, Edmonton, AB, Canada
During fasting, the liver increases lipid storage as a mean
to reserve and provide energy for vital cellular functions. After re-feeding,
hepatocytes rapidly decrease the number and size of lipid droplets (LD). Little
is known about the liver LD proteome and changes in the proteome during the
fasting/re-feeding transition. This study aimed to investigate the hepatic LD
proteome in fasted and re-fed conditions in the mouse. For this purpose we
utilized 4 month old male C57BL/6 mice. Mice were randomly split into two
groups: fasted (24 h fast) and re-fed (24 h fast followed by 6 h re-feeding).
At the end of each period mice were sacrificed by cardiac puncture, livers were
harvested, rinsed in ice-cold PBS and immediately subjected to homogenization.
LD proteins were resolved in 10% SDS-PAGE and analyzed by LC-MS/MS. We found a
total of 425 proteins associated with LD in the fasting state, while 346
proteins were found in the LD during the fad state. While 292 proteins were
common for both energetic states, 133 LD-associated proteins were unique for
fasting and 45 were unique for re-feeding state. Some of the shared LD proteins
in different feeding states were the canonical LD markers perilipin 2, perilipin
3, CTP:phosphocholine cytidylyltransferase A (CCT-á), lipases, acyl-CoA ligases
and acyltransferases. Several endoplasmic reticulum markers have also been
found, including calnexin and proteins normally localized to the lumen of this
organelle. Among fasting unique proteins we found perilipin 5, ABHD5/CGI-58 and long-chain-fatty-acid-CoA ligase 1 (ACSL-1) and several mitochondrial
and peroxisomal marker proteins, supporting the role of LDs in the provision of
substrates for fatty acid oxidation. Re-feeding unique proteins included
AGPAT2, S-adenosylmethionine synthase 1 and Steroid 17-alpha-hydroxylase among
others. These results indicate the dynamic nature of hepatic LD proteome according
to the energetic requirements of the cell.