2018
Mol Metab. 2018 Mar;9:207-216. doi: 10.1016/j.molmet.2017.11.008. Epub 2017 Nov 24.
Desacetyl-α-melanocyte stimulating hormone and α-melanocyte stimulating hormone are required to regulate energy balance.
Department of Physiology, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; Department of Molecular Medicine and Pathology, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand. Department of Internal Medicine, Division of Hypothalamic Research, The University of Texas Southwestern Medical Center, Dallas, TX, USA. Department of Anatomy and Medical Imaging, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand. Department of Physiology, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand. Department of Pharmacy, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand. Department of Clinical Biochemistry, Cambridge Institute for Medical Research, Addenbrooke's Hospital, Cambridge CB2 2QR, United Kingdom; University of Cambridge Metabolic Research Laboratories, MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge CB2 0QQ, United Kingdom.
Service type: Knock-in mice
Abstract
OBJECTIVE: Regulation of energy balance depends on pro-opiomelanocortin (POMC)-derived peptides and melanocortin-4 receptor (MC4R). Alpha-melanocyte stimulating hormone (α-MSH) is the predicted natural POMC-derived peptide that regulates energy balance. Desacetyl-α-MSH, the precursor for α-MSH, is present in brain and blood. Desacetyl-α-MSH is considered to be unimportant for regulating energy balance despite being more potent (compared with α-MSH) at activating the appetite-regulating MC4R in vitro. Thus, the physiological role for desacetyl-α-MSH is still unclear. METHODS: We created a novel mouse model to determine whether desacetyl-α-MSH plays a role in regulating energy balance. We engineered a knock in targeted QKQR mutation in the POMC protein cleavage site that blocks the production of both desacetyl-α-MSH and α-MSH from adrenocorticotropin (ACTH1-39). RESULTS: The mutant ACTH1-39 (ACTHQKQR) functions similar to native ACTH1-39 (ACTHKKRR) at the melanocortin 2 receptor (MC2R) in vivo and MC4R in vitro. Male and female homozygous mutant ACTH1-39 (Pomctm1/tm1) mice develop the characteristic melanocortin obesity phenotype. Replacement of either desacetyl-α-MSH or α-MSH over 14 days into Pomctm1/tm1 mouse brain significantly reverses excess body weight and fat mass gained compared to wild type (WT) (Pomcwt/wt) mice. Here, we identify both desacetyl-α-MSH and α-MSH peptides as regulators of energy balance and highlight a previously unappreciated physiological role for desacetyl-α-MSH. CONCLUSIONS: Based on these data we propose that there is potential to exploit the naturally occurring POMC-derived peptides to treat obesity but this relies on first understanding the specific function(s) for desacetyl-α-MSH and α-MSH.
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