SAP97 and Dendritic Branching

Last week we learned that blocking expression of the AMPA receptor GluR1 subunit in motor neurons reduces dendrite growth, leading to impaired motor function.  This week, Zhou et al.  Begin to unravel the molecular mechanisms tying GluR1 to activity-dependent dendritic growth.  Intracellularly, glutamate receptors interact with membrane-associated guanylate kinases (MAGUKs)—scaffolding proteins that form the postsynaptic density and anchor signaling and other effector molecules near receptors.  GluR1 interacts with the MAGUK synapse-associated protein 97 (SAP97).  Overexpression of SAP97 increased dendritic branching, whereas SAP97 knockdown decreased branching in motor neurons.  This effect was blocked by an AMPA receptor antagonist.  Interaction between GluR1 and SAP97 was required for either to enhance dendritic branching, but only because the interaction localizes SAP97 to the plasma membrane.  If SAP97 was targeted to the membrane by the addition of a palmitoylation sequence, its effects on dendritic branching were restored in the absence of direct interaction with GluR1.

• Machinery That Helps Make Memories
• K0ATP Expression Affects Seizure Susceptibility
• Endocytosis Related Proteins in Neuronal Polarity
• Fatal Trigger Excitement Through Matrix Fragments
• Neuronal Activity Leads to Alzheimers Protein Cleavage