Structure–function analysis of SAP97, a modular scaffolding protein that drives dendrite growth

Abstract

Activation of AMPA receptors assembled with the GluA1 subunit can promote dendrite growth in a manner that depends on its direct binding partner, SAP97. SAP97 is a modular scaffolding protein that has at least seven recognizable protein-protein interaction domains. Several complementary approaches were employed to show that the dendrite branching promoting action of full length SAP97 depends on ligand(s) that bind to the PDZ3 domain. Ligand(s) to PDZ1, PDZ2 and I3 domains also contribute to dendrite growth. The ability of PDZ3 ligand(s) to promote dendrite growth depends on localization at the plasma membrane along with GluA1 and SAP97. These results suggest that the assembly of a multi-protein complex at or near synapses is vital for the translation of AMPA-R activity into dendrite growth.

Resequencing and Association Analysis of Six PSD-95-Related Genes as Possible Susceptibility Genes for Schizophrenia and Autism Spectrum Disorders

“…The second PDZ domain (PDZ2) of SAP-97, where DLG1 -G344R is located, folds into a compact globular domain comprising six β-strands and two α-helices, which is a typical architecture for PDZ domains. During synaptic transmission, SAP-97 interacts with key protein partners such as ligand-binding units in α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) 53 64 and N-methyl-D-aspartate receptor (NMDAR) 57 through the PDZ2 domain to regulate glutamate signaling and neuronal growth, which are major factors in the pathogenesis of SZ and ASD. The same domain also functions as a binding site for receptors for the neurotrophic growth factors corticotropin-releasing hormone (CRF) 65 and epidermal growth factor receptor (ErbB1) 66 , which are linked to SZ.…”

“…The mutation calls were then validated for confidence by Sanger sequencing using the BigDye Terminator v3.1 Cycle Sequencing Kit (Applied Biosystems, USA). Genotyping prioritization was based on whether the mutation was 1) located in a functional domain or motif of the protein, according to the Human Protein Reference Database ( http://www.hprd.org ), Pfam ( http://pfam.xfam.org/ ), and existing literature 21 50 51 52 53 54 55 56 57 58 59 , 2) functionally important, such as causing a frame shift, stop gain, or cysteine gain/loss, 3) novel, as in not documented in the NCBI dbSNP database (Build 137) ( http://www.ncbi.nlm.nih.gov/SNP/ ), the 1000 Genomes Project ( http://www.1000genomes.org/ ), the Exome Variant Server of NHLBI GO Exome Sequencing Project (ESP6500SI-V2) ( http://evs.gs.washington.edu/EVS/ ), or the Human Genetic Variation Database of Japanese genetic variation consortium ( http://www.genome.med.kyoto-u.ac.jp/SnpDB ), and 4) predicted to be deleterious by in silico analytic methods. In addition to PolyPhen-2 ( http://genetics.bwh.harvard.edu/pph2/ ) and SIFT ( http://sift.jcvi.org/ ) that were originally incorporated in the Ingenuity Variant Caller, we also employed PROVEAN ( http://provean.jcvi.org/index.php ), PMut ( http://www.ngrl.org.uk/Manchester/page/pmut ), Mutation Taster ( http://www.mutationtaster.org/ ), and PANTHER ( http://pantherdb.org/ ) for enhanced prediction of the consequences of protein alterations.…”

H3K9me3 Inhibition Improves Memory, Promotes Spine Formation, and Increases BDNF Levels in the Aged Hippocampus

“…Specifically, we quantified the levels of PSD95 (scaffolding protein) and GluR1 (subunit of AMPA receptors), as the activity-dependent incorporation of AMPA receptor at PSDenriched regions promotes spine growth and increases synaptic transmission efficiency (Zhang et al, 2015a). After mice treatment, hippocampal synaptosome fractions were immunostained and analyzed by flow synaptometry, which first identifies synaptosomes by size using calibrated beads, as previously described (Prieto et al, 2015).…”

The central role of heat shock factor 1 in synaptic fidelity and memory consolidation

“…SAP97 is a scaffolding protein that stabilizes the synapse and drives dendritic growth (Zhang et al 2015b). In a comprehensive study, Ting et al (2011) examined HSF1-mediated upregulation of SAP97 in cultured atrial cardiomyocytes, a synaptic rich tissue.…”