title: B56beta, a regulatory subunit of protein phosphatase 2A, interacts with CALEB/NGC and inhibits CALEB/NGC-mediated dendritic branching.
abstract: The development of dendritic arbors is critical in neuronal circuit formation, as dendrites are the primary sites of synaptic input. Morphologically specialized dendritic protrusions called spines represent the main postsynaptic compartment for excitatory neurotransmission. Recently, we demonstrated that chicken acidic leucine-rich epidermal growth factor (EGF) -like domain-containing brain protein/neuroglycan C (CALEB/NGC), a neural member of the EGF family, mediates dendritic tree and spine complexity but that the signaling pathways in the respective processes differ. For a more detailed characterization of these signal transduction pathways, we performed a yeast two-hybrid screen to identify proteins that interact with CALEB/NGC. Our results show that B56beta, a regulatory subunit of protein phosphatase 2A, interacts with CALEB/NGC and inhibits CALEB/NGC-mediated dendritic branching but not spine formation. Binding of B56beta to CALEB/NGC was confirmed by several biochemical and immunocytochemical assays. Using affinity chromatography and mass spectrometry, we demonstrate that the whole protein phosphatase 2A trimer, including structural and catalytic subunits, binds to CALEB/NGC via B56beta. We show that CALEB/NGC induces the phosphorylation of Akt in dendrites. Previously described to interfere with Akt signaling, B56beta inhibits Akt phosphorylation and Akt-dependent dendritic branching but not Akt-independent spine formation induced by CALEB/NGC. Our results contribute to a better understanding of signaling specificity leading to neuronal process differentiation in sequential developmental events.
authors.affiliation: Institute of Cell Biology and Neurobiology, Center for Anatomy, Charité-Universitätsmedizin Berlin, Charitéplatz 1, D-10117 Berlin, Germany.
authors.forename: Nicola
authors.initials: N
authors.lastname: Brandt
authors.forename: Kristin
authors.initials: K
authors.lastname: Franke
authors.forename: Sascha
authors.initials: S
authors.lastname: Johannes
authors.forename: Friedrich
authors.initials: F
authors.lastname: Buck
authors.forename: Sönke
authors.initials: S
authors.lastname: Harder
authors.forename: Burkhard
authors.initials: B
authors.lastname: Hassel
authors.forename: Robert
authors.initials: R
authors.lastname: Nitsch
authors.forename: Stefan
authors.initials: S
authors.lastname: Schumacher
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000201:enzymology; D003001:Cloning, Molecular; D003712:Dendrites / Q000502:physiology* / Q000648:ultrastructure; D015723:Gene Library; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016133:Polymerase Chain Reaction; D054648:Protein Phosphatase 2 / Q000235:genetics / Q000378:metabolism*; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism*
chemical_list: D008565:Membrane Proteins; D010446:Peptide Fragments; D021122:Protein Subunits; D005982:Glutathione Transferase; C503493:PPP2R5B protein, human; D054648:Protein Phosphatase 2