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Team:BGU Israel/Project/Hormone Workshop
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Revision as of 17:14, 17 October 2014
Backgroud
The Problem: Abnormal aggregation of fatty acid in non-adipose tissues, particularly skeletal muscles and liver
The Goal: Reduce insulin resistance and improve the metabolism of metabolic syndrome patients
Mechanism
The most active form of the Adiponectin is a high molecular weight complex. The synthesis of the protein subunit and an enzyme for disulfide bonds should improve the levels of the active form of the hormone.
Background
Adiponectin is an adipocyte derived protein hormone showing insulin - sensitizing effect and has an important role in lipid and glucose metabolism regulation. Hypoadiponectemia (low levels of serum Adiponectin) is highly related with occurrence of abdominal obesity, insulin resistance, type 2 diabetes, and the metabolic syndrome. Adiponectin forms multimeric complexes that combine via its collagen domain to create three major oligomeric forms: a low molecular weight (LMW) trimer, a middle - molecular weight (MMW) hexamer, and high molecular weight (HMW) 12-18- mer Adiponectin. The form showing the most relevant properties considering insulin sensitivity and protection from diabetes is the HMW form of the hormone (Kadowaki et al., 2006).
Figure 1. Adiponectin oligomeric forms
Mechanism
When one is diagnosed with the metabolic syndrome's symptoms and shows low levels of serum Adiponectin, an efficient treatment could be a pill or a shot containing the active HMW form of Adiponectin hormone. However, there is no known efficient synthetic method to produce the desired multimer structure of the hormone. It has been shown that overexpression of the enzyme DsbA-L (disulfide-bond A oxidoreductase - like), promotes Adiponectin multimerization, while suppressing its expression by RNAi markedly and selectively reduced Adiponectin levels and secretion in adipocytes (Liu et al., 2008).
In order to synthesize the HMW form of Adiponectin, we intend to introduce overexpression of both Adiponectin and DsbA-L in our model cell line HepG2 (human hepatocellular carcinoma). This is expected to produces high levels of HMW Adiponectin while relying on the natural hormone secreting ability of hepatocytes and excretion tags on the hormone itself.
In the future, we intend to attach the hormone to an inducible system to allow for more control on the proteins synthesis.
Click on the picture to check out the machanism 
Adiponectin is overexpressed
References
Kadowaki, T., Yamauchi, T., Kubota, N., Hara, K., Ueki, K., & Tobe, K. (2006). Review series Adiponectin and adiponectin receptors in insulin resistance , diabetes , and the metabolic syndrome. J Clin Invest., 116(7), 1784–1792. doi:10.1172/JCI29126.1784
Liu, M., Zhou, L., Xu, A., Lam, K. S. L., Wetzel, M. D., Xiang, R., Liu, F. (2008). A disulfide-bond A oxidoreductase-like protein (DsbA-L) regulates adiponectin multimerization. Proceedings of the National Academy of Sciences of the United States of America, 105(47), 18302–7. doi:10.1073/pnas.0806341105
