Expression and stability of two isoforms of ABCG1 in human vascular cells.
OBJECTIVE
To evaluate the expression of two ABCG1 isoforms that differ in the presence or absence of a 12 amino acid (AA) peptide between the ABC cassette and the transmembrane region, termed ABCG1(+12) and ABCG1(-12), respectively, in human vascular cells and tissues.


RESULTS
mRNA for both isoforms was expressed in human macrophages, vascular endothelial and smooth muscle cells as well as whole human spleen, lung, liver and brain tissue. However, ABCG1(+12) was not expressed in mouse tissues. 2D gel electrophoresis of ABCG1 protein indicated that both protein isoforms were expressed in human macrophages. Furthermore the half-lives of the two ABCG1 protein isoforms, stably expressed in CHOK1 cells, measured under basal conditions were different, suggesting the presence of a degradation or stabilising signal in or near the 12AA region of ABCG1(+12).


CONCLUSIONS
ABCG1(+12) is an isoform of ABCG1 exclusively expressed in human cells at the RNA and protein level. As ABCG1(+12) is not expressed in mice, although mouse models are widely used to elucidate the function of ABCG1, further investigations into the importance of this human ABCG1 isoform are warranted.
Gelissen
Ingrid C
IC
Centre for Vascular Research, University of New South Wales, Sydney, Australia.
Cartland
Sian
S
Brown
Andrew J
AJ
Sandoval
Cecilia
C
Kim
Mijurng
M
Dinnes
Donna Lee
DL
Lee
Youra
Y
Hsieh
Victar
V
Gaus
Katharina
K
Kritharides
Leonard
L
Jessup
Wendy
W
D000070998:ATP Binding Cassette Transporter, Subfamily G, Member 1; D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis* / Q000502:physiology; D000818:Animals; D001808:Blood Vessels / Q000166:cytology* / Q000378:metabolism*; D002478:Cells, Cultured; D006801:Humans; D051379:Mice; D020033:Protein Isoforms; D055550:Protein Stability
C419353:ABCG1 protein, human; D000070998:ATP Binding Cassette Transporter, Subfamily G, Member 1; D018528:ATP-Binding Cassette Transporters; D020033:Protein Isoforms