Identification of a new functional domain in angiopoietin-like 3 (ANGPTL3) and angiopoietin-like 4 (ANGPTL4) involved in binding and inhibition of lipoprotein lipase (LPL).
Angiopoietin-like 3 (ANGPTL3) and angiopoietin-like 4 (ANGPTL4) are secreted proteins that regulate triglyceride (TG) metabolism in part by inhibiting lipoprotein lipase (LPL). Recently, we showed that treatment of wild-type mice with monoclonal antibody (mAb) 14D12, specific for ANGPTL4, recapitulated the Angptl4 knock-out (-/-) mouse phenotype of reduced serum TG levels. In the present study, we mapped the region of mouse ANGPTL4 recognized by mAb 14D12 to amino acids Gln(29)-His(53), which we designate as specific epitope 1 (SE1). The 14D12 mAb prevented binding of ANGPTL4 with LPL, consistent with its ability to neutralize the LPL-inhibitory activity of ANGPTL4. Alignment of all angiopoietin family members revealed that a sequence similar to ANGPTL4 SE1 was present only in ANGPTL3, corresponding to amino acids Glu(32)-His(55). We produced a mouse mAb against this SE1-like region in ANGPTL3. This mAb, designated 5.50.3, inhibited the binding of ANGPTL3 to LPL and neutralized ANGPTL3-mediated inhibition of LPL activity in vitro. Treatment of wild-type as well as hyperlipidemic mice with mAb 5.50.3 resulted in reduced serum TG levels, recapitulating the lipid phenotype found in Angptl3(-/-) mice. These results show that the SE1 region of ANGPTL3 and ANGPTL4 functions as a domain important for binding LPL and inhibiting its activity in vitro and in vivo. Moreover, these results demonstrate that therapeutic antibodies that neutralize ANGPTL4 and ANGPTL3 may be useful for treatment of some forms of hyperlipidemia.
Lee
E-Chiang
EC
Departments of Biotherapeutics Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381. Electronic address: elee@lexpharma.com.
Desai
Urvi
U
Pharmaceutical Biology Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381.
Gololobov
Gennady
G
Departments of Biotherapeutics Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381.
Hong
Seokjoo
S
Departments of Biotherapeutics Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381.
Feng
Xiao
X
Departments of Biotherapeutics Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381.
Yu
Xuan-Chuan
XC
Pharmaceutical Discovery Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381.
Gay
Jason
J
Pharmaceutical Biology Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381.
Wilganowski
Nat
N
Pharmaceutical Biology Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381.
Gao
Cuihua
C
Departments of Biotherapeutics Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381.
Du
Ling-Ling
LL
Departments of Biotherapeutics Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381.
Chen
Joan
J
Departments of Biotherapeutics Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381.
Hu
Yi
Y
Molecular Biology, Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381.
Zhao
Sharon
S
Molecular Biology, Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381.
Kirkpatrick
Laura
L
Departments of Biotherapeutics Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381.
Schneider
Matthias
M
Pharmaceutical Biology Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381.
Zambrowicz
Brian P
BP
Departments of Biotherapeutics Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381; Pharmaceutical Biology Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381; Pharmaceutical Discovery Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381; Molecular Biology, Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381.
Landes
Greg
G
Departments of Biotherapeutics Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381.
Powell
David R
DR
Pharmaceutical Biology Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381.
Sonnenburg
William K
WK
Departments of Biotherapeutics Lexicon Pharmaceuticals Inc., The Woodlands, Texas 77381. Electronic address: wsonnenburg@lexpharma.com.