Heterodimerization of hypothalamic G-protein-coupled receptors involved in weight regulation.
BACKGROUND
Melanocortin 3 and 4 receptors (MC3R and MC4R) are known to play an essential role in hypothalamic weight regulation. In addition to these two G-protein-coupled receptors (GPCRs), a huge number of other GPCRs are expressed in hypothalamic regions, and some of them are involved in weight regulation. So far, homodimerization was shown for a few of these receptors. Heterodimerization of unrelated receptors may have profound functional consequence but heterodimerization of GPCRs involved in weight regulation was not reported yet.


METHODS
A selective number of hypothalamically expressed GPCRs were cloned into a eukaryotic expression vector. Cell surface expression was demonstrated by an ELISA approach. Subcellular distribution was investigated by confocal laser microscopy. A sandwich ELISA and fluorescence resonance energy transfer (FRET) were used to determine protein-protein interaction.


RESULTS
Via sandwich ELISA and FRET approach we could demonstrate a robust interaction of the MC4R with GPR7, both of which are expressed in the hypothalamic nucleus paraventricularis. Moreover, we determined a strong interaction of MC3R with the growth hormone secretagogue receptor expressed in the nucleus arcuatus.


CONCLUSIONS
Identification GPCR heterodimerization adds to the understanding of the complexity of weight regulation and may provide important information to develop therapeutic strategies to treat obesity.
Rediger
Anne
A
Institute of Experimental Pediatric Endocrinology, Charité - Universitatsmedizin Berlin, Germany.
Tarnow
Patrick
P
Bickenbach
Annika
A
Schaefer
Michael
M
Krude
Heiko
H
Gruters
Annette
A
Biebermann
Heike
H
D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000378:metabolism*; D001835:Body Weight / Q000502:physiology*; D019556:COS Cells; D002522:Chlorocebus aethiops; D019281:Dimerization; D004797:Enzyme-Linked Immunosorbent Assay; D031541:Fluorescence Resonance Energy Transfer; D015870:Gene Expression / Q000502:physiology; D006801:Humans; D007668:Kidney / Q000166:cytology; D009765:Obesity / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D010286:Paraventricular Hypothalamic Nucleus / Q000378:metabolism*; D043884:Receptor, Cannabinoid, CB1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D044104:Receptor, Melanocortin, Type 3 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D044105:Receptor, Melanocortin, Type 4 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D044302:Receptor, Serotonin, 5-HT1B / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018013:Receptors, Neuropeptide / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017476:Receptors, Neuropeptide Y / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017450:Receptors, Opioid, mu / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018000:Receptors, Peptide / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014162:Transfection
C505392:MC3R protein, human; C470072:MC4R protein, human; C485722:NPBWR1 protein, human; D043884:Receptor, Cannabinoid, CB1; D044104:Receptor, Melanocortin, Type 3; D044105:Receptor, Melanocortin, Type 4; D044302:Receptor, Serotonin, 5-HT1B; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D018013:Receptors, Neuropeptide; D017476:Receptors, Neuropeptide Y; D017450:Receptors, Opioid, mu; D018000:Receptors, Peptide; C035560:glutathione receptor; C095889:neuropeptide Y2 receptor