Table 1 Mouse models with mutations in the melanocortin system
# | Allele | Gene | Function | Mutation | Effect | Body length | Effect on fur color |
|---|---|---|---|---|---|---|---|
1 | Obese (ob) | Leptin | Cytokine hormone secreted by adipocytes | Natural | Loss-of-function | ↓ | − |
2 | Diabetes (db) | Leptin receptor | Cytokine receptor | Natural | Loss-of-function | ↓ | − |
3 | Agouti (Ay) | Agouti | Antagonist of Mc1r | Natural | Gain-of-function | ↑ | + |
4 | Agrp | Agouti-related protein | Antagonist of hypothalamic MCRs | Transgenic | Over-expression | ↑ | − |
5 | Pomc | Pro-opiomelanocortin | Protein precursor for MCR agonist | Gene targeting | Knock-out | ↑ | + |
6 | Fat(fat) | Carbooxypeptidase E | Pomc maturation | Natural | Loss-of-function | – | − |
7 | Mc4r | Melanocortin-4- receptor | Integration of energy related peripheral signals | Gene targeting | Knock-out | ↑ | − |
8 | Sim1 | Single-minded 1 | Putative target of MC4R signaling | Gene targeting | Loss-of-function, | ↑ | − |