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APP Is a Context-Sensitive Regulator of the Hippocampal Presynaptic Active Zone.

Laßek M, Weingarten J, Wegner M, Mueller BF, Rohmer M, Baeumlisberger D, Arrey TN, Hick M, Ackermann J, Acker-Palmer A, Koch I, Müller U, Karas M, Volknandt W - PLoS Comput. Biol. (2016)

Bottom Line: Subsequently, an isobaric labeling was performed using TMT6 for protein identification and quantification by high-resolution mass spectrometry.The impact of APP deletion on the hippocampal PAZ proteome was visualized by creating protein-protein interaction (PPI) networks that incorporated APP into the synaptic vesicle cycle, cytoskeletal organization, and calcium-homeostasis.The combination of subcellular fractionation, immunopurification, proteomic analysis, and bioinformatics allowed us to identify APP as structural and functional regulator in a context-sensitive manner within the hippocampal active zone network.

View Article: PubMed Central - PubMed

Affiliation: Institute for Cell Biology and Neuroscience, Biologicum, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany.

ABSTRACT
The hallmarks of Alzheimer's disease (AD) are characterized by cognitive decline and behavioral changes. The most prominent brain region affected by the progression of AD is the hippocampal formation. The pathogenesis involves a successive loss of hippocampal neurons accompanied by a decline in learning and memory consolidation mainly attributed to an accumulation of senile plaques. The amyloid precursor protein (APP) has been identified as precursor of Aβ-peptides, the main constituents of senile plaques. Until now, little is known about the physiological function of APP within the central nervous system. The allocation of APP to the proteome of the highly dynamic presynaptic active zone (PAZ) highlights APP as a yet unknown player in neuronal communication and signaling. In this study, we analyze the impact of APP deletion on the hippocampal PAZ proteome. The native hippocampal PAZ derived from APP mouse mutants (APP-KOs and NexCreAPP/APLP2-cDKOs) was isolated by subcellular fractionation and immunopurification. Subsequently, an isobaric labeling was performed using TMT6 for protein identification and quantification by high-resolution mass spectrometry. We combine bioinformatics tools and biochemical approaches to address the proteomics dataset and to understand the role of individual proteins. The impact of APP deletion on the hippocampal PAZ proteome was visualized by creating protein-protein interaction (PPI) networks that incorporated APP into the synaptic vesicle cycle, cytoskeletal organization, and calcium-homeostasis. The combination of subcellular fractionation, immunopurification, proteomic analysis, and bioinformatics allowed us to identify APP as structural and functional regulator in a context-sensitive manner within the hippocampal active zone network.

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Relative abundance of proteins mapped to the functional subnetwork of the cytoskeleton organization.A Impact of APP deletion. B Impact of the NexCre-cDKO. Change in abundance of more than ±10% is reflected by increasing sizes of nodes. The color code corresponds to the degree of up- (magenta) and downregulation (green). Nodes in yellow represent proteins with changes in abundance of less than ±10%. Abbreviations are the respective gene names of individual proteins as given in UniProt database and in the supplementary information S1 Table.
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pcbi.1004832.g007: Relative abundance of proteins mapped to the functional subnetwork of the cytoskeleton organization.A Impact of APP deletion. B Impact of the NexCre-cDKO. Change in abundance of more than ±10% is reflected by increasing sizes of nodes. The color code corresponds to the degree of up- (magenta) and downregulation (green). Nodes in yellow represent proteins with changes in abundance of less than ±10%. Abbreviations are the respective gene names of individual proteins as given in UniProt database and in the supplementary information S1 Table.

Mentions: APP is strongly interconnected with proteins governing cytoskeletal organization (S2 Fig). Important connections for the information flow within this network are via actin and the microtubule motor dynein. Several organizers of the cytoskeleton are affected by APP deletion (Fig 7A) such as coactosin-like protein (86.3±4.4%, Cotl1), cofilin-1 (83.1±4.7%, Cfl1), tropomyosin alpha-1 chain (80.6±2.5%, Tpm1), and vimentin (113.9±2.6%, Vim). Especially in the NexCre-cDKO (Fig 7B) the MARCKS-related protein (74.3±7.1%, Marcksl1) that interacts with calmodulin, and actin is downregulated. Other affected proteins are cofilin-1 (83.5±2.2%, Cfl1), tropomyosin alpha-1 chain (86.7±2.8%, Tpm1), actin-related protein 2/3 complex subunit 4 (87.1±0.4%, Arpc4) and subunit 5 (86.1±1.0%, Arpc5), and the src substrate cortactin (87.4±4.4%, Cttn).


APP Is a Context-Sensitive Regulator of the Hippocampal Presynaptic Active Zone.

Laßek M, Weingarten J, Wegner M, Mueller BF, Rohmer M, Baeumlisberger D, Arrey TN, Hick M, Ackermann J, Acker-Palmer A, Koch I, Müller U, Karas M, Volknandt W - PLoS Comput. Biol. (2016)

Relative abundance of proteins mapped to the functional subnetwork of the cytoskeleton organization.A Impact of APP deletion. B Impact of the NexCre-cDKO. Change in abundance of more than ±10% is reflected by increasing sizes of nodes. The color code corresponds to the degree of up- (magenta) and downregulation (green). Nodes in yellow represent proteins with changes in abundance of less than ±10%. Abbreviations are the respective gene names of individual proteins as given in UniProt database and in the supplementary information S1 Table.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4836664&req=5

pcbi.1004832.g007: Relative abundance of proteins mapped to the functional subnetwork of the cytoskeleton organization.A Impact of APP deletion. B Impact of the NexCre-cDKO. Change in abundance of more than ±10% is reflected by increasing sizes of nodes. The color code corresponds to the degree of up- (magenta) and downregulation (green). Nodes in yellow represent proteins with changes in abundance of less than ±10%. Abbreviations are the respective gene names of individual proteins as given in UniProt database and in the supplementary information S1 Table.
Mentions: APP is strongly interconnected with proteins governing cytoskeletal organization (S2 Fig). Important connections for the information flow within this network are via actin and the microtubule motor dynein. Several organizers of the cytoskeleton are affected by APP deletion (Fig 7A) such as coactosin-like protein (86.3±4.4%, Cotl1), cofilin-1 (83.1±4.7%, Cfl1), tropomyosin alpha-1 chain (80.6±2.5%, Tpm1), and vimentin (113.9±2.6%, Vim). Especially in the NexCre-cDKO (Fig 7B) the MARCKS-related protein (74.3±7.1%, Marcksl1) that interacts with calmodulin, and actin is downregulated. Other affected proteins are cofilin-1 (83.5±2.2%, Cfl1), tropomyosin alpha-1 chain (86.7±2.8%, Tpm1), actin-related protein 2/3 complex subunit 4 (87.1±0.4%, Arpc4) and subunit 5 (86.1±1.0%, Arpc5), and the src substrate cortactin (87.4±4.4%, Cttn).

Bottom Line: Subsequently, an isobaric labeling was performed using TMT6 for protein identification and quantification by high-resolution mass spectrometry.The impact of APP deletion on the hippocampal PAZ proteome was visualized by creating protein-protein interaction (PPI) networks that incorporated APP into the synaptic vesicle cycle, cytoskeletal organization, and calcium-homeostasis.The combination of subcellular fractionation, immunopurification, proteomic analysis, and bioinformatics allowed us to identify APP as structural and functional regulator in a context-sensitive manner within the hippocampal active zone network.

View Article: PubMed Central - PubMed

Affiliation: Institute for Cell Biology and Neuroscience, Biologicum, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany.

ABSTRACT
The hallmarks of Alzheimer's disease (AD) are characterized by cognitive decline and behavioral changes. The most prominent brain region affected by the progression of AD is the hippocampal formation. The pathogenesis involves a successive loss of hippocampal neurons accompanied by a decline in learning and memory consolidation mainly attributed to an accumulation of senile plaques. The amyloid precursor protein (APP) has been identified as precursor of Aβ-peptides, the main constituents of senile plaques. Until now, little is known about the physiological function of APP within the central nervous system. The allocation of APP to the proteome of the highly dynamic presynaptic active zone (PAZ) highlights APP as a yet unknown player in neuronal communication and signaling. In this study, we analyze the impact of APP deletion on the hippocampal PAZ proteome. The native hippocampal PAZ derived from APP mouse mutants (APP-KOs and NexCreAPP/APLP2-cDKOs) was isolated by subcellular fractionation and immunopurification. Subsequently, an isobaric labeling was performed using TMT6 for protein identification and quantification by high-resolution mass spectrometry. We combine bioinformatics tools and biochemical approaches to address the proteomics dataset and to understand the role of individual proteins. The impact of APP deletion on the hippocampal PAZ proteome was visualized by creating protein-protein interaction (PPI) networks that incorporated APP into the synaptic vesicle cycle, cytoskeletal organization, and calcium-homeostasis. The combination of subcellular fractionation, immunopurification, proteomic analysis, and bioinformatics allowed us to identify APP as structural and functional regulator in a context-sensitive manner within the hippocampal active zone network.

Show MeSH
Related in: MedlinePlus