|
|
| TR |
TITLE |
AUTHORS |
KEYWORDS |
MATERIALS & METHODS
|
MICROSCOPIC
TECHNIQUES |
SPECIES |
MORPHOLOGY |
CELL
LINE |
| 623 |
Activation
of the Leptin Receptor by a Ligand-induced
Conformational Change of Constitutive Receptor Dimers |
Cyril
Couturier, Ralf Jockers |
leptin,
Bioluminescence Resonance Energy Transfer approach, leptin receptor
isoform |
COS-7 cells transfected with
either OBRs–YFP or OB-Rl–YFP expression plasmids were grown on 35-mm glass-bottomed microwell
dishes (Plastek Cultureware, MatTek Corp., Ashland, MA).
|
fluorescence
microscopy |
|
|
HEK
293, HeLa |
| |
Binding of leptin to the leptin receptor is crucial
for body weight and bone mass regulation in mammals. Leptin receptors were shown to exist as
dimers, but the role of dimerization in receptor activation remains unknown. Using a quantitative
Bioluminescence Resonance Energy Transfer approach, we show here in living cells that 60% of
the leptin receptor exists as constitutive dimers at physiological expression levels in the
absence of leptin. No further increase in leptin receptor dimerization was detected in the presence
of leptin. Importantly, in cells expressing the short leptin receptor isoform, leptin promoted
a robust enhancement of energy transfer signals that reflect specific conformational changes
of pre-existing leptin receptor dimers and that may be used as read-out in screening assays
for leptin receptor ligands. Both leptin receptor dimerization and the leptin-induced energy
transfer were Janus kinase 2-independent. Taken together, our data support a receptor activation
model based on ligand-induced conformational changes rather than ligand-induced dimerization. |
|
|
|
|
