Exciting recent genetic studies implicate the scaffold protein SH2B1 in human disease. Human mutations in SH2B1 are associated with severe early onset obesity with disproportionately severe insulin resistance, impaired brain development, and, in some cases, short stature. This phenotype (strikingly similar to that of SH2B1-/- mice) is consistent with SH2B1 being a signaling molecule for multiple ligands, including growth hormone (GH), leptin, and insulin. SH2B1 is recruited to JAK2 and is a critical component in GH regulation of the actin cytoskeleton, a prerequisite for cellular proliferation, differentiation and migration. However, the mechanism by which SH2B1 facilitates GH-induced changes in the actin cytoskeleton remains largely unknown. The long-term goal is to understand the mechanism by which SH2B1 contributes to the function of GH and other ligands, and to gain insight into unrecognized cellular actions of GH;new functions of SH2B1;and how scaffold proteins such as SH2B1 move highly regulated and dynamic complexes from membrane-bound receptors to multiple, often remote, sites in the cell (e.g., focal adhesions, lamellipodia, cytoplasm, nucleus). The objective of the current proposal is to understand how SH2B1 regulates assembly and movement of """"""""signaling complexes"""""""" and whether dysregulation of these functions contributes to defects in cellular function and ultimately human obesity, insulin-resistance, neurologic disorders, and suppressed growth. The central hypothesis is that SH2B1 facilitates the formation and/or movement of SH2B1 """"""""signaling complexes"""""""" to specific locations in the cell (e.g., pm, lamellipodia, cytoplasm, nucleus) in response to GH. These functions of SH2B1 enhance GH regulation of the actin cytoskeleton, GH-induced motility, and GH responses in the nucleus. They are critical to normal human physiology, such that their impairment due to mutation contributes to the dramatic phenotype observed in human patients. Guided by strong preliminary data, this hypothesis will be tested by pursuing three specific aims: 1) Elucidate the mechanism by which SH2B1 reversibly localizes to the plasma membrane, cytosol and nucleus. 2) Determine the role of SH2B1 in regulating GH-induced changes in the actin cytoskeleton, cell motility, and trafficking of proteins between intracellular compartments. 3) Determine the functional consequences of mutations in SH2B1 associated with human disease. Experiments will use a combination of biochemical, immunologic, cell biology, and imaging techniques standard in the lab. State-of-the-art microscopes, photoactivable probes, proteomics, cell lines and both primary macrophages and MEFs from SH2B1-/- mice, will also be used. The concept that the nuclear localization signal of SH2B1 is a dual function motif that mediates both nuclear import and plasma membrane binding that is regulated by phosphorylation of nearby serines is innovative. The proposed research is significant because it will provide insight into the role of SH2B1 in the function of GH and the numerous other ligands (e.g., leptin, insulin, nerve growth factor) that utilize SH2B1 as a signaling protein.
These studies will provide insight into the role of a multifunctional adapter protein SH2B1 in the function of growth hormone and the many other cytokines, hormones and growth factors (e.g. leptin, insulin, nerve growth factor) that use SH2B1 to mediate their effects in cells. Such insight is critical to our understanding on how growth hormone brings about its well known diverse effects in the body, including body growth and metabolism, and other SH2B1 activating ligands contribute to, prevent and/or alleviate symptoms of a variety of diseases including obesity, various cancers, diabetes, multiple sclerosis, and diseases of the immune system.
|Joe, Ray M; Flores, Anabel; Doche, Michael E et al. (2017) Phosphorylation of the Unique C-terminal Tail of the Alpha Isoform of the Scaffold Protein SH2B1 Controls the Ability of SH2B1alpha to Enhance Nerve Growth Factor Function. Mol Cell Biol :|
|Carter-Su, Christin; Schwartz, Jessica; Argetsinger, Lawrence S (2016) Growth hormone signaling pathways. Growth Horm IGF Res 28:11-5|
|Xue, Xiang; Ramakrishnan, Sadeesh K; Weisz, Kevin et al. (2016) Iron Uptake via DMT1 Integrates Cell Cycle with JAK-STAT3 Signaling to Promote Colorectal Tumorigenesis. Cell Metab 24:447-461|
|Pearce, Laura R; Joe, Ray; Doche, Michael E et al. (2014) Functional characterization of obesity-associated variants involving the ? and ? isoforms of human SH2B1. Endocrinology 155:3219-26|
|Su, Hsiao-Wen; Lanning, Nathan J; Morris, David L et al. (2013) Phosphorylation of the adaptor protein SH2B1? regulates its ability to enhance growth hormone-dependent macrophage motility. J Cell Sci 126:1733-43|
|Javadi, Mojib; Hofstätter, Edda; Stickle, Natalie et al. (2012) The SH2B1 adaptor protein associates with a proximal region of the erythropoietin receptor. J Biol Chem 287:26223-34|
|Doche, Michael E; Bochukova, Elena G; Su, Hsiao-Wen et al. (2012) Human SH2B1 mutations are associated with maladaptive behaviors and obesity. J Clin Invest 122:4732-6|
|Lanning, Nathan J; Su, Hsiao-Wen; Argetsinger, Lawrence S et al. (2011) Identification of SH2B1? as a focal adhesion protein that regulates focal adhesion size and number. J Cell Sci 124:3095-105|
|Maures, Travis J; Su, Hsiao-Wen; Argetsinger, Lawrence S et al. (2011) Phosphorylation controls a dual-function polybasic nuclear localization sequence in the adapter protein SH2B1? to regulate its cellular function and distribution. J Cell Sci 124:1542-52|
|Maures, Travis J; Chen, Linyi; Carter-Su, Christin (2009) Nucleocytoplasmic shuttling of the adapter protein SH2B1beta (SH2-Bbeta) is required for nerve growth factor (NGF)-dependent neurite outgrowth and enhancement of expression of a subset of NGF-responsive genes. Mol Endocrinol 23:1077-91|
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