Cell Signaling Technology

Product Pathways - Growth Factors/Cytokines

Human Leptin/OB (hLeptin) #5719

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Source

Recombinant human Leptin (hLeptin) Val22-Cys167 (Accession #NP_000221) was produced in E.coli at Cell Signaling Technology.

Molecular Characterization

Recombinant hLeptin has a Met on the amino terminus and has a calculated MW of 16,026. DTT-reduced and non-reduced protein migrate as 15 kDa polypeptides. The expected amino-terminal MVPIQ of recombinant hLeptin was verified by amino acid sequencing.

Purity

>98% as determined by SDS-PAGE of 6 μg reduced (+) and non-reduced (-) recombinant hLeptin. All lots are greater than 98% pure.

Bioactivity

The bioactivity of recombinant hLeptin was determined by its ability to induce TNF-α production from MCF7 cells. The minimum concentration used to obtain this effect was 50 µg/ml.

Coomassie Gel

Coomassie Gel

The purity of recombinant hLeptin was determined by SDS-PAGE of 6 µg reduced (+) and non-reduced (-) recombinant hLeptin and staining overnight with Coomassie Blue.

Bioactivity

Bioactivity

The production of TNF-α by MCF7 cells cultured with increasing concentrations of hLeptin was assessed. Cells were treated with hLeptin alone, boiled hLeptin, or hLeptin in the presence of a neutralizing antibody. Media from cells incubated with hLeptin for 24 hr was collected and assayed for TNF-α using the SignalKine™ Human TNF-α Sandwich ELISA Kit #7289 and the OD450 was determined.

Bioactivity

Bioactivity

The proliferation of leptin receptor-transfected BaF3 cells treated with increasing concentrations of hLeptin was assessed. After 48 hr treatment with hLeptin, cells were incubated with a tetrazolium salt and the OD450 - OD650 was determined.


Bioactivity

Bioactivity

The production of TNF-α by MCF7 cells cultured with increasing concentrations of hLeptin was assessed. Media from cells incubated with hLeptin for 24 hr was collected and assayed for TNF-α using the SignalKine™ Human TNF-α Sandwich ELISA Kit #7289 and the OD450 was determined.

Endotoxin

Less than 0.01 ng endotoxin/1 μg hLeptin.

Formulation

With carrier: Lyophilized from a 0.22 μm filtered solution of PBS, pH 7.2 containing 20 μg BSA per 1 μg hLeptin. Carrier free: Lyophilized from a 0.22 μm filtered solution of PBS, pH 7.2.

Background

Leptin is a 16 kDa adipocyte-derived hormone that relays the status of the body’s energy reserves to the hypothalamus, resulting in the suppression of appetite and modulation of energy expenditure (1,2). Leptin functions as a pleiotropic cytokine with multiple roles in immune function and reproduction (1-4). There are at least five isoforms of the leptin receptor, but only OB-Rb is signaling competent (1,2). OB-Rb is expressed on a number of cells, including T cells, B cells, keratinocytes, and others (1-6). Leptin/OB-Rb interactions induce Jak2, PI3K, Erk1/2, and Stat3 activation (1,2). OB-Rb is often highly expressed in many tumor types, including breast, pancreatic, and Tumor Initiating Stem Cells (TISCS), providing a potential mechanistic link for the tumor promoting effects of obesity (2,7).

  1. Faggioni, R. et al. (2001) FASEB J 15, 2565-71.
  2. Park, J. et al. (2011) Endocr Rev 32, 550-70.
  3. Mancuso, P. et al. (2011) J Immunol 186, 1081-90.
  4. Hausman, G.J. and Barb, C.R. (2010) Endocr Dev 19, 31-44.
  5. Kanda, N. and Watanabe, S. (2008) Endocrinology 149, 5189-98.
  6. Tanaka, M. et al. (2011) J Neurosci 31, 8373-80.
  7. Feldman, D.E. et al. (2012) Proc Natl Acad Sci U S A 109, 829-34.

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For Research Use Only. Not For Use In Diagnostic Procedures.

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