Taking STEPs forward to understand fragile X syndrome.
A priority of fragile X syndrome (FXS) research is to determine the molecular mechanisms underlying the functional, behavioral, and structural deficits in humans and in the FXS mouse model. Given that metabotropic glutamate receptor (mGluR) long-term depression (LTD) is exaggerated in FXS mice, considerable effort has focused on proteins that regulate this form of synaptic plasticity. STriatal-Enriched protein tyrosine Phosphatase (STEP) is a brain-specific phosphatase implicated as an "LTD protein" because it mediates AMPA receptor internalization during mGluR LTD. STEP also promotes NMDA receptor endocytosis and inactivates ERK1/2 and Fyn, thereby opposing synaptic strengthening. We hypothesized that dysregulation of STEP may contribute to the pathophysiology of FXS. We review how STEP's expression and activity are regulated by dendritic protein synthesis, ubiquitination, proteolysis, and phosphorylation. We also discuss implications for STEP in FXS and other disorders, including Alzheimer's disease. As highlighted here, pharmacological interventions targeting STEP may prove successful for FXS.
Yale University School of Medicine, New Haven, CT 06520, USA. susan.goebel-goody@yale.edu
Susan M
SM
Goebel-Goody
Paul J
PJ
Lombroso
D017398:Alternative Splicing; D016229:Amyloid beta-Peptides / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000033:anatomy & histology / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D051860:Fragile X Messenger Ribonucleoprotein 1 / Q000235:genetics / Q000378:metabolism; D005600:Fragile X Syndrome / Q000201:enzymology* / Q000503:physiopathology*; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D054558:Protein Tyrosine Phosphatases, Non-Receptor / Q000235:genetics / Q000378:metabolism*; D051076:Proto-Oncogene Proteins c-fyn / Q000378:metabolism; D018091:Receptors, AMPA / Q000378:metabolism; D018094:Receptors, Metabotropic Glutamate / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism
D016229:Amyloid beta-Peptides; D048049:Extracellular Signal-Regulated MAP Kinases; D051860:Fragile X Messenger Ribonucleoprotein 1; D007527:Isoenzymes; D054558:Protein Tyrosine Phosphatases, Non-Receptor; D051076:Proto-Oncogene Proteins c-fyn; D018091:Receptors, AMPA; D018094:Receptors, Metabotropic Glutamate; D016194:Receptors, N-Methyl-D-Aspartate; C489930:PTPN5 protein, human