Individuals with autism spectrum disorders (ASDs) demonstrate impairment in social interactions and problems in verbal and nonverbal communication. Autism spectrum disorders are thought to affect 1 in 88 children in the US. Recent research has shown that epidermal growth factor receptor (EGFR) activation is associated with nerve cell development and repair. Mitogen inducible gene 6 (MIG-6) is a 58-kDa non-kinase scaffolding adaptor protein consisting of 462 amino-acids, which has been shown to be a negative feedback regulator of EGFR and Met receptor tyrosine kinase (RTK) signaling.
SUBJECTS AND METHODS
In this study, we determined plasma levels of MIG-6, which suppresses the EGFR RTK pathway in autistic children, and compared MIG-6 levels with the EGFR ligand, epidermal growth factor (EGF), and the cMET ligand, hepatocyte growth factor (HGF). MIG-6 levels were also compared to the symptom severity of 19 different autistic behaviors.
Plasma MIG-6 concentration was measured in 40 autistic children and 39 neurotypical, age, and gender similar controls using an enzyme linked immunosorbent assay (ELISA). Plasma MIG-6 levels were compared to putative biomarkers known to be associated with EGFR and cMET and severity levels of 19 autism related symptoms [awareness, expressive language, receptive language, (conversational) pragmatic language, focus/attention, hyperactivity, impulsivity, perseveration, fine motor skills, gross motor skills, hypotonia (low muscle tone), tip toeing, rocking/pacing, stimming, obsessions/fixations, eye contact, sound sensitivity, light sensitivity, and tactile sensitivity].
In this study, we found that plasma MIG-6 levels in autistic children (182.41 ± 24.3 pg/ml) were significantly lower than neurotypical controls (1779.76 ± 352.5; P = 1.76E − 5). Decreased MIG-6 levels correlated with serotonin, dopamine, Tumor necrosis factor alpha (TNF-alpha), and urokinase receptor (uPAR) concentration, but not with other tested putative biomarkers. MIG-6 levels also correlated significantly with severity of expressive language, receptive language, tip toeing, rocking/pacing, and hand flapping/stimming.
These results suggest a relationship between decreased plasma MIG-6 levels, biomarkers associated with the EGFR pathway, and symptom severity in autism. A strong correlation between plasma MIG-6 and dopamine and serotonin levels suggest that decreased MIG-6 levels may be associated with abnormal neurotransmitter synthesis and/or action. A strong correlation between MIG-6 and uPAR and the inflammatory marker TNF-alpha suggests that low MIG-6 levels may be associated with the HGF/Met signaling pathway, as well as inflammation in autistic children.