Objective Currently no effective disease modifying agents exist for the treatment of AD. The Fyn tyrosine kinase is implicated in Alzheimer’s disease (AD) pathology triggered by amyloid-β oligomers (Aβo) and propagated by Tau. Thus, Fyn inhibition may prevent or delay disease progression. Here, we sought to repurpose the Src family kinase inhibitor oncology compound, AZD0530, for AD. Methods The pharmacokinetics and distribution of AZD0530 were evaluated in mice. Inhibition of Aβo signaling to Fyn, Pyk2 and Glu receptors by AZD0530 was tested by brain slice assays. After AZD0530 or vehicle treatment of wild type and AD transgenic mice, memory was assessed by Morris water maze and novel object recognition. For these cohorts, APP metabolism, synaptic markers (SV2 and PSD-95), and targets of Fyn (Pyk2 and Tau) were studied by immunohistochemistry and by immunoblotting. Results AZD0530 potently inhibits Fyn and prevents both Aβo-induced Fyn signaling and downstream phosphorylation of the AD risk gene product, Pyk2, and of NR2B Glu receptors in brain slices. After 4 weeks of treatment, AZD0530 dosing of APP/PS1 transgenic mice fully rescues spatial memory deficits and synaptic depletion, without altering APP or Aβ metabolism. AZD0530 treatment also reduces microglial activation in APP/PS1 mice, and rescues Tau phosphorylation and deposition abnormalities in APP/PS1/Tau transgenic mice. There is no evidence of AZD0530 chronic toxicity. Interpretation Targeting Fyn can reverse memory deficits found in AD mouse models, and rescue synapse density loss characteristic of the disease. Thus, AZD0530 is a promising candidate to test as a potential therapy for AD.

IRSp53 is an adaptor protein that acts downstream of Rac and Cdc42 small GTPases and is implicated in

Diacylglycerol (DAG) is an important lipid signalling molecule that exerts an effect on various effector proteins including protein kinase C. A main mechanism for DAG removal is to convert it to phosphatidic acid (PA) by DAG kinases (DGKs). However, it is not well understood how DGKs are targeted to specific subcellular sites and tightly regulates DAG levels. The neuronal synapse is a prominent site of DAG production. Here, we show that DGKf is targeted to excitatory synapses through its direct interaction with the postsynaptic PDZ scaffold PSD-95. Overexpression of DGKf in cultured neurons increases the number of dendritic spines, which receive the majority of excitatory synaptic inputs, in a manner requiring its catalytic activity and PSD-95 binding. Conversely, DGKf knockdown reduces spine density. Mice deficient in DGKf expression show reduced spine density and excitatory synaptic transmission. Time-lapse imaging indicates that DGKf is required for spine maintenance but not formation. We propose that PSD-95 targets DGKf to synaptic DAG-producing receptors to tightly couple synaptic DAG production to its conversion to PA for the maintenance of spine density.

BackgroundAlzheimer’s disease (AD), the most common neurodegenerative disorder, is characterized by the deposition of extracellular amyloid plaques and intracellular neurofibrillary tangles. To understand the pathological mechanisms underlying AD, developing animal models that completely encompass the main features of AD pathologies is indispensable. Although mouse models that display pathological hallmarks of AD (amyloid plaques, neurofibrillary tangles, or both) have been developed and investigated, a systematic approach for understanding the molecular characteristics of AD mouse models is lacking.MethodsTo elucidate the mechanisms underlying the contribution of amyloid beta (Aβ) and tau in AD pathogenesis, we herein generated a novel animal model of AD, namely the AD-like pathology with amyloid and neurofibrillary tangles (ADLPAPT) mice. The ADLPAPT mice carry three human transgenes, including amyloid precursor protein, presenilin-1, and tau, with six mutations. To characterize the molecular and functional signatures of AD in ADLPAPT mice, we analyzed the hippocampal proteome and performed comparisons with individual-pathology transgenic mice (i.e., amyloid or neurofibrillary tangles) and wild-type mice using quantitative proteomics with 10-plex tandem mass tag.ResultsThe ADLPAPT mice exhibited accelerated neurofibrillary tangle formation in addition to amyloid plaques, neuronal loss in the CA1 area, and memory deficit at an early age. In addition, our proteomic analysis identified nearly 10,000 protein groups, which enabled the identification of hundreds of differentially expressed proteins (DEPs) in ADLPAPT mice. Bioinformatics analysis of DEPs revealed that ADLPAPT mice experienced age-dependent active immune responses and synaptic dysfunctions.ConclusionsOur study is the first to compare and describe the proteomic characteristics in amyloid and neurofibrillary tangle pathologies using isobaric label-based quantitative proteomics. Furthermore, we analyzed the hippocampal proteome of the newly developed ADLPAPT model mice to investigate how both Aβ and tau pathologies regulate the hippocampal proteome. Because the ADLPAPT mouse model recapitulates the main features of AD pathogenesis, the proteomic data derived from its hippocampus has significant utility as a novel resource for the research on the Aβ-tau axis and pathophysiological changes in vivo.Electronic supplementary materialThe online version of this article (10.1186/s13024-017-0234-4) contains supplementary material, which is available to authorized users.

Na؉ /H ؉ exchanger 3 (NHE3) plays a pivotal role in transepithelial Na ؉ and HCO 3 ؊ absorption across a wide range of epithelia in the digestive and renal-genitourinary systems. Accumulating evidence suggests that PDZ-based adaptor proteins play an important role in regulating the trafficking and activity of NHE3. A search for NHE3-binding modular proteins using yeast two-hybrid assays led us to the PDZ-based adaptor Shank2. The interaction between Shank2 and NHE3 was further confirmed by immunoprecipitation and surface plasmon resonance studies. When expressed in PS120/ NHE3 cells, Shank2 increased the membrane expression and basal activity of NHE3 and attenuated the cAMP-dependent inhibition of NHE3 activity. Furthermore, knock-down of native Shank2 expression in Caco-2 epithelial cells by RNA interference decreased NHE3 protein expression as well as activity but amplified the inhibitory effect of cAMP on NHE3. These results indicate that Shank2 is a novel NHE3 interacting protein that is involved in the fine regulation of transepithelial salt and water transport through affecting NHE3 expression and activity.Maintenance of intracellular and systemic pH, Na ϩ concentration, and fluid volume is essential for maintaining the physiological status in cells and whole organisms (1, 2). First demonstrated almost 30 years ago (3), members of the mammalian Na ϩ /H ϩ exchanger (NHE) 2 family participate in the regulation of these parameters at both cellular and systemic levels. To date, nine NHE family members have been identified in mammalian cells with unique tissue distribution and functional properties (2). As a better characterized isoform, NHE3 is primarily found in the apical membrane of epithelial cells of the renal and gastrointestinal tracts, where it mediates transepithelial absorption of Na ϩ and HCO 3 Ϫ (2, 4). Lack of NHE3 activity impairs acid-base balance and extracellular fluid volume homeostasis (5).NHE3 is known to be regulated by a large variety of hormones, such as ␣-and ␤-adrenergic agonists, dopamine, parathyroid hormone, and angiotensin II via multiple signaling systems (6, 7), but the exact underlying mechanisms are still only partially understood. Nevertheless, it has been known for many years that acute regulation of NHE3 activity is linked to protein phosphorylation, as in the case of inhibition by cAMPdependent protein kinase A (PKA) (7,8). Subsequently, it has been demonstrated that adaptor proteins with PDZ (PSD-95/discs large/ ZO-1) domains play an important role in the cAMP-dependent inhibition of NHE3 in a number of systems (7, 9, 10). For example, EBP50 (also known as NHERF1) and E3KARP (also known as NHERF2, SIP-1, or TKA-1) were found to be necessary modular proteins that participated in the cAMP-dependent PKA phosphorylation of NHE3 by forming a multiprotein signaling complex (11,12).In recent years, there has been a growing interest in PDZ domains and modular proteins having PDZ domains. Best studied in the post-synaptic density (PSD) region of neurons, PDZ domain proteins have em...