Leptin (human, recombinant)

Leptin is a peptide hormone that regulates energy homeostasis, growth, and reproduction, as well as immune function.¹ It is secreted by adipocytes and regulated by nutritional status, where fasting reduces leptin levels and feeding increases leptin levels, as well as in a circadian manner, with serum levels peaking at night.^2,3 Circulating leptin can bind leptin receptors expressed by peripheral immune cells, such as macrophages, natural (NK) cells, and B and T cells, or be transported across the blood brain barrier, where it binds to neuronally expressed leptin receptors.¹ Binding of leptin to the leptin receptor induces the recruitment and phosphorylation of JAK2, leading to activation of a variety of intracellular signaling cascades, including MAPK-, STAT-, PI3K-, and AMPK-mediated pathways.² Leptin-dependent signaling pathways promote energy expenditure, growth, and reproductive functions, reduce food intake and the production of adrenal corticosteroids, and enhance innate and adaptive immune responses.¹ Leptin-deficient ob/ob mice exhibit severe obesity, hyperlipidemia, hyperglycemia, and hyperinsulinemia and are a commonly used model of obesity and type 2 diabetes.⁴ Serum leptin levels are increased in individuals with a variety of conditions, including obesity or insulin resistance.⁵ Cayman's Leptin (human, recombinant) protein can be used for binding assays. The protein was synthesized from a DNA sequence encoding the mature form of human leptin (Val22-Cys167) with an N-terminal translation-initiating methionine (Met1). The expressed protein consists of 147 amino acids, has a calculated molecular weight of 16 kDa, and a predicted N-terminus of Met1.

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1. Pan, W.W., and Myers, M.G., Jr. Leptin and the maintenance of elevated body weight. Nat. Rev. Neurosci. 19(2), 95-105 (2018).

2. Münzberg, H., and Morrison, C.D. Structure, production and signaling of leptin. Metabolism 64(1), 13-23 (2015).

3. Serin, Y., and Tek, N.A. Effect of circadian rhythm on metabolic processes and the regulation of energy balance. Ann. Nutr. Metab. 74(4), 322-330 (2019).

4. Wang, B., Chandrasekera, P.C., and Pippin, J.J. Leptin- and leptin receptor-deficient rodent models: Relevance for human type 2 diabetes. Curr. Diabetes Rev. 10(2), 131-145 (2014).

5. Fischer, S., Hanefeld, M., Haffner, S.M., et al. Insulin-resistant patients with type 2 diabetes mellitus have higher serum leptin levels independently of body fat mass. Acta Diabetol. 39(3), 105-110 (2002).