Vol. 276, Issue 5, E815-E821, May 1999
Regional specificity of ASP binding in human adipose
tissue
Jumana
Saleh,
Nick
Christou, and
Katherine
Cianflone
1 Mike Rosenbloom Laboratory
for Cardiovascular Research and
2 Department of Surgery,
McGill University Health Center, McGill University, Montreal, Quebec,
Canada H3A 1A1
Obesity, in particular omental (OM) adiposity,
is associated with diabetes and cardiovascular disease. Thus
site-specific regulation of fat storage is important to understand.
Acylation-stimulating protein (ASP) is a potent stimulator of glucose
transport and triglyceride synthesis in adipocytes. In the present
study, we characterized receptor binding of
125I-labeled ASP to human
adipocyte plasma membranes from paired OM and subcutaneous (SC) sites
in normal (N) and obese (O) male (M) and female (F) subjects
(n = 24). Overall, specific binding of
125I-ASP was in the order of SC > OM and O > N (in SC tissue, particularly in F). Receptor affinity
of 125I-ASP was higher
[lower dissociation constant
(Kd)]
in SC than in OM (63.6 ± 16.2 vs. 160.7 ± 38.6 nM,
P < 0.02), especially in F (37.0 ± 11.1 F-N and 26.3 ± 6.7 nM F-O) and lower (higher Kd) in male OM
(291.8 ± 116.8 M-N and 149.4 ± 56.4 M-O). The greater binding and
higher affinity of 125I-ASP
binding to SC suggests that ASP may be an important factor in
maintaining regional adipose tissue mass. Conversely, lower binding and
receptor affinity in male OM adipose tissue may contribute to the fatty
acid imbalance and metabolic complications associated with this
syndrome, by reducing the efficiency of adipose fatty acid trapping by
the ASP pathway.
acylation-stimulating protein; complement C3a; receptor; triglyceride synthesis
