Deciphering adaptor specificity in GFL-dependent RET-mediated proliferation and neurite outgrowth

• Published in: Journal of neurochemistry 2007-08, Vol.102 (4), p.1184-1194
• Main Authors: Gustin, Jason A, Yang, Mao, Johnson, Eugene M. Jr, Milbrandt, Jeffrey
• Format: Article
• Language: English
• Subjects: Adaptor Proteins, Signal Transducing - metabolism; Animals; Biochemistry; Biological and medical sciences; Cancer; Cell adhesion & migration; Cell Line, Transformed; Cell Movement - drug effects; Cell Movement - physiology; Cell Proliferation - drug effects; Endocrinopathies; Enzyme Activation - drug effects; Enzyme Activation - genetics; Fibroblasts - cytology; General aspects. Associated endocrine diseases. Endocrine paraneoplasic syndromes; Glial Cell Line-Derived Neurotrophic Factor - pharmacology; GRB2 Adaptor Protein - metabolism; growth factor receptor binding protein 2; Kidneys; Kinases; Lentivirus; Malformations of the urinary system; Medical sciences; Mutation; Mutation - physiology; Nephrology. Urinary tract diseases; Neurites - drug effects; Neurites - physiology; Neurosciences; PC12 Cells; proliferation; Proto-Oncogene Proteins c-ret - genetics; Proto-Oncogene Proteins c-ret - physiology; Rats; RET; RNA, Small Interfering - pharmacology; Shc Signaling Adaptor Proteins; small interfering RNA; Src Homology 2 Domain-Containing, Transforming Protein 1; Src-homology 2; Tyrosine - genetics
• ISSN: 0022-3042; 1471-4159
• DOI: 10.1111/j.1471-4159.2007.04624.x

Glial cell derived neurotrophic factor (GDNF)-dependent receptor tyrosine kinase RET activity is required for proper development of the nervous system and genitourinary tract. Loss-of-function mutations in RET are associated with enteric nervous system abnormalities (Hirschsprung disease) and renal deficits (Potter's syndrome), whereas activating mutations lead to hereditary cancer syndromes (multiple endocrine neoplasia type 2A and type 2B). RET activation is crucial for the proper regulation of a variety of cellular processes including cell migration, proliferation and neurite outgrowth. By analyzing a series of RET mutants we found that Y1062 was critical for stimulating GDNF-mediated proliferation as well as proliferation stimulated by GDNF-independent oncogenic forms of RET. Studies using small interfering RNA driven by lentivirus to knock-down expression of particular adaptor proteins that interact with RET phospho-Y1062, demonstrated that only Src-homology 2 and growth factor receptor binding protein 2 were necessary for RET-mediated proliferation by wild type and oncogenic forms of RET. Interestingly, we discovered that Y1062 was also required for GDNF-stimulated neurite outgrowth. However, small interfering RNAs to either Src-homology 2 or growth factor receptor binding protein 2 or a panel of other adaptor proteins known to interact with RET Y1062 were incapable of blocking GDNF-stimulated neurite formation, indicating that differential use of intracellular adaptors is responsible for regulating alternative RET-stimulated cellular events such as proliferation versus a differentiation response like neurite outgrowth.