ADAM10 hyperactivation acts on piccolo to deplete synaptic vesicle stores in Huntington’s disease

Abstract

Synaptic dysfunction and cognitive decline in Huntington’s disease (HD) involve hyperactive A disintegrin and metalloproteinase domain-containing protein 10 (ADAM10). To identify the molecular mechanisms through which ADAM10 is associated with synaptic dysfunction in HD, we performed an immunoaffinity purification-mass spectrometry (IP-MS) study of endogenous ADAM10 in the brains of wild-type and HD mice. In the normal brain, proteins implicated in synapse organization, synaptic plasticity, and vesicle and organelles trafficking interact with ADAM10, suggesting that it may act as a hub protein at the excitatory synapse. Importantly, the ADAM10 interactome is enriched in presynaptic proteins and ADAM10 coimmunoprecipitates with piccolo (PCLO), a key player in the recycling and maintenance of synaptic vesicles (SVs). In contrast, reduced ADAM10/PCLO immunoprecipitation occurs in the HD brain, with decreased density of SVs in the reserve and docked pool at the HD presynaptic terminal. Conditional heterozygous deletion of ADAM10 in the forebrain of HD mice reduces active ADAM10 to wild-type level, and normalizes ADAM10/PCLO complex formation and SVs density and distribution. The results indicate that presynaptic ADAM10 and PCLO are a relevant component of HD pathogenesis.

Huntingtin and the Synapse

“…ADAM10 localizes presynaptically with SVs, suggesting a role in presynaptic regulation ( Lundgren et al, 2020 ). While Alzheimer disease (AD) is associated with reduced ADAM10 levels ( Kuhn et al, 2010 ), thereby resulting in excess amyloidogenic processing of amyloid precursor protein, ADAM10 is hyperactive in the HD brain at both pre- and postsynaptic localizations ( Cozzolino et al, 2021 ). Using immunoprecipitation followed by mass spectrometry and gene ontology analysis, it was found that the ADAM10 interactome exhibits substantial overlap with the wtHTT interactome; many of the shared interactors were identified as proteins essential for presynaptic function, thereby highlighting a putative functional role for both wtHTT and ADAM10 at the presynaptic active zone.…”

“…Using immunoprecipitation followed by mass spectrometry and gene ontology analysis, it was found that the ADAM10 interactome exhibits substantial overlap with the wtHTT interactome; many of the shared interactors were identified as proteins essential for presynaptic function, thereby highlighting a putative functional role for both wtHTT and ADAM10 at the presynaptic active zone. For example, both ADAM10 ( Cozzolino et al, 2021 ) and wtHTT ( Yao et al, 2014 ) bind to piccolo, a large cytomatrix protein that is critical for SV maintenance and efficient SV recycling ( Ackermann et al, 2019 ). Hyperactive ADAM10, which can be induced either by pathogenic polyQ expansion of HTT or by wtHTT loss ( Lo Sardo et al, 2012 ), disrupts the ADAM10/piccolo complex, resulting in depleted SVs at the readily releasable and reserve vesicle pools.…”

“…Hyperactive ADAM10, which can be induced either by pathogenic polyQ expansion of HTT or by wtHTT loss ( Lo Sardo et al, 2012 ), disrupts the ADAM10/piccolo complex, resulting in depleted SVs at the readily releasable and reserve vesicle pools. Restoring ADAM10 activity to control levels in HD mice, achieved by crossing R6/2 mice with heterozygous conditional ADAM10 knockout mice (CaMKIIα-Cre:Adam10 Flox/+ ), restored the ADAM10/piccolo interaction and replenished SV stores ( Cozzolino et al, 2021 ). Thus, wtHTT loss may have detrimental effects on presynaptic homeostasis by interrupting the HTT/ADAM10/piccolo complex.…”

The endogenous HBZ interactome in ATL leukemic cells reveals an unprecedented complexity of host interacting partners involved in RNA splicing

“…Each band of sample and control was subjected to an in situ trypsin hydrolysis procedure ( 24 ) and the peptide mixtures were analyzed by nano-Liquid Chromatography-tandem Mass Spectrometry (nano-LC-MS/MS) using an LTQ Orbitrap XL mass spectrometer (Thermo Fisher Scientific Inc., Waltham, MA, USA) equipped with a Proxeon nanoEasy II capillary High Performance Liquid Chromatography (HPLC). The nano-LC-MS/MS analyses were performed as described elsewhere ( 25 ). The raw data were processed into mgf files and proteins identified by means of Mascot licensed software (Matrix Science Boston, USA) using the Homo Sapiens National Center of Biotechnology Information (NCBI) database.…”

Molecular Pathophysiological Mechanisms in Huntington’s Disease

“…Another protein, huntingtin-interacting protein 1 (HIP1) is involved in cytoskeleton assembly and dendritic development [ 72 , 73 ], while binding of Htt to protein kinase C and postsynaptic density 95 (PSD95) regulates synaptic activity [ 74 ] and anchoring of postsynaptic glutamate receptors [ 75 ]. Through interaction with ADAM10 (A Disintegrin and metalloproteinase domain-containing protein 10), a transmembrane protease, Htt regulates presynaptic neurotransmission, an essential step for the normal functioning of synapses [ 76 , 77 ]. The protein has also an important role in the transcription of many genes.…”