J. Sevalle

TREM 2 shedding by cleavage at the H157‐S158 bond is accelerated for the Alzheimer's disease‐associated H157Y variant

EMBO Molecular Medicine, 2017

We have characterised the proteolytic cleavage events responsible for the shedding of triggering ... more We have characterised the proteolytic cleavage events responsible for the shedding of triggering receptor expressed on myeloid cells 2 (TREM2) from primary cultures of human macrophages, murine microglia and TREM2-expressing human embryonic kidney (HEK293) cells. In all cell types, a soluble 17 kDa N-terminal cleavage fragment was shed into the conditioned media in a constitutive process that is inhibited by G1254023X and metalloprotease inhibitors and siRNA targeting ADAM10. Inhibitors of serine proteases and matrix metalloproteinases 2/9, and ADAM17 siRNA did not block TREM2 shedding. Peptidomimetic protease inhibitors highlighted a possible cleavage site, and mass spectrometry confirmed that shedding occurred predominantly at the H157-S158 peptide bond for both wild-type and H157Y human TREM2 and for the wild-type murine orthologue. Crucially, we also show that the Alzheimer's disease-associated H157Y TREM2 variant was shed more rapidly than wild type from HEK293 cells, possibly by a novel, batimastat-and ADAM10-siRNA-independent, sheddase activity. These insights offer new therapeutic targets for modulating the innate immune response in Alzheimer's and other neurological diseases.

format_quoteIdentified the sheddase activity as sensitive to metalloprotease inhibitors, revealing proteolytic cleavage at H157-S158 bond in TREM2.format_quote

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Current and future implications of basic and translational research on amyloid-β peptide production and removal pathways

Molecular and cellular neurosciences, Jan 4, 2015

Inherited variants in multiple different genes are associated with increased risk for Alzheimer&#... more Inherited variants in multiple different genes are associated with increased risk for Alzheimer's disease (AD). In many of these genes, the inherited variants alter some aspect of the production or clearance of the neurotoxic amyloid β-peptide (Aβ). Thus missense, splice site or duplication mutants in the presenilin 1 (PS1), presenilin 2 (PS2) or the amyloid precursor protein (APP) genes, which alter the levels or shift the balance of Aβ produced, are associated with rare, highly penetrant autosomal dominant forms of Familial Alzheimer's Disease (FAD). Similarly, the more prevalent late-onset forms of AD are associated with both coding and non-coding variants in genes such as SORL1, PICALM and ABCA7 that affect the production and clearance of Aβ. This review summarises some of the recent molecular and structural work on the role of these genes and the proteins coded by them in the biology of Aβ. We also briefly outline how the emerging knowledge about the pathways involved i...

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The gamma/epsilon-secretase-derived APP intracellular domain fragments regulate p53

Current Alzheimer research, 2007

Amyloid beta-peptide (Abeta), which plays a central role in Alzheimer Disease, is generated by pr... more Amyloid beta-peptide (Abeta), which plays a central role in Alzheimer Disease, is generated by presenilin-dependent and presenilin-independent gamma-secretase cleavages of beta-amyloid precursor protein (betaAPP). We report that the presenilins (PS1 and PS2) also regulate p53-associated cell death. Thus, we established that PS deficiency, catalytically inactive PS mutants, gamma-secretase inhibitors and betaAPP or APLP2 depletion reduced the expression and activity of p53, and lowered the transactivation of its promoter and mRNA levels. p53 expression was also reduced in the brains or betaAPP-deficient mice or in brains where both PS had been invalidated by double conditional knock out. AICDC59 and AICDC50, the gamma- and epsilon-secretase-derived C-terminal fragments of betaAPP, respectively, trigger the activation of caspase-3, p53-dependent cell death, and increase p53 activity and mRNA. Finally, HEK293 cells expressing PS1 harboring familial AD (FAD) mutations or FAD-affected br...

Presenilin-Dependent -Secretase-Mediated Control of p53-Associated Cell Death in Alzheimer's Disease

Journal of Neuroscience, 2006

Presenilins (PSs) are part of the ␥-secretase complex that produces the amyloid ␤-peptide (A␤) fr... more Presenilins (PSs) are part of the ␥-secretase complex that produces the amyloid ␤-peptide (A␤) from its precursor [␤-amyloid precursor protein (␤APP)]. Mutations in PS that cause familial Alzheimer's disease (FAD) increase A␤ production and trigger p53-dependent cell death. We demonstrate that PS deficiency, catalytically inactive PS mutants, ␥-secretase inhibitors, and ␤APP or amyloid precursor protein-like protein 2 (APLP2) depletion all reduce the expression and activity of p53 and lower the transactivation of its promoter and mRNA expression. p53 expression also is diminished in the brains of PS-or ␤APP-deficient mice. The ␥and-secretase-derived amyloid intracellular C-terminal domain (AICD) fragments (AICDC59 and AICDC50, respectively) of ␤APP trigger p53-dependent cell death and increase p53 activity and mRNA. Finally, PS1 mutations enhance p53 activity in human embryonic kidney 293 cells and p53 expression in FAD-affected brains. Thus our study shows that AICDs control p53 at a transcriptional level, in vitro and in vivo, and that FAD mutations increase p53 expression and activity in cells and human brains.

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Response to Correspondence: Pardossi-Piquard et al., “Presenilin-Dependent Transcriptional Control of the Aβ-Degrading Enzyme Neprilysin by Intracellular Domains of βAPP and APLP.” Neuron 46, 541–554

Neuron, 2007

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Parkin acts as a transcription factor modulating presenilin-1 and presenilin-2 promoter transactivations

Molecular Neurodegeneration, 2013

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Further characterization of a putative serine protease contributing to the γ-secretase cleavage of β-amyloid precursor protein

Bioorganic & Medicinal Chemistry, 2013

The 3-alkoxy-7-amino-4-chloro-isocoumarins JLK-6 and JLK-2 have been shown to markedly reduce the... more The 3-alkoxy-7-amino-4-chloro-isocoumarins JLK-6 and JLK-2 have been shown to markedly reduce the production of Amyloid b-peptide (Ab) by Amyloid-b Precursor Protein (APP) expressing HEK293 cells by affecting the c-secretase cleavage of APP, with no effect on the cleavage of the Notch receptor. This suggested that these compounds do not directly inhibit the presenilin-dependent c-secretase complex but more likely interfere with an upstream target involved in c-secretase-associated pathway. The mechanism of action of these compounds is unknown and there are high fundamental and therapeutical interests to unravel their target. Isocoumarin compounds were previously shown to behave as potent mechanism-based irreversible inhibitors of serine proteases, suggesting that the JLK-directed target could belong to such enzyme family. To get further insight into structure-activity relationships and to develop more potent isocoumarin derivatives, we have synthesized and evaluated a series of isocoumarin analogues with modifications at positions 3, 4 and 7. In particular, the 7-amino group was substituted with either acyl, urethane, alkyl or aryl groups, which could represent additional interaction sites. Altogether, the results highlighted the essential integrity of the 3-alkoxy-7-amino-4-chloro-isocoumarin scaffold for Ab-lowering activity and supported the involvement of a serine protease, or may be more generally, a serine hydrolase. The newly reported 7-N-alkyl series produced the most active compounds with an IC 50 between 10 and 30 lM. Finally, we also explored peptide boronates, a series of reversible serine protease inhibitors, previously shown to also lower cellular Ab production. The presented data suggested they could act on the same target or interfere with the same pathway as isocoumarins derivatives.

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P1-449: Aminopeptidase A is involved in amyloid beta peptide N-terminal truncation

Alzheimer's & Dementia, 2008

P3-238

Alzheimer's & Dementia, 2006

Presenilin-Dependent -Secretase-Mediated Control of p53Associated Cell Death in Alzheimer's Disease

Journal of Neuroscience - J NEUROSCI, 2006

Presenilins (PSs) are part of the ␥-secretase complex that produces the amyloid ␤-peptide (A␤) fr... more Presenilins (PSs) are part of the ␥-secretase complex that produces the amyloid ␤-peptide (A␤) from its precursor [␤-amyloid precursor protein (␤APP)]. Mutations in PS that cause familial Alzheimer's disease (FAD) increase A␤ production and trigger p53-dependent cell death. We demonstrate that PS deficiency, catalytically inactive PS mutants, ␥-secretase inhibitors, and ␤APP or amyloid precursor protein-like protein 2 (APLP2) depletion all reduce the expression and activity of p53 and lower the transactivation of its promoter and mRNA expression. p53 expression also is diminished in the brains of PS-or ␤APP-deficient mice. The ␥and-secretase-derived amyloid intracellular C-terminal domain (AICD) fragments (AICDC59 and AICDC50, respectively) of ␤APP trigger p53-dependent cell death and increase p53 activity and mRNA. Finally, PS1 mutations enhance p53 activity in human embryonic kidney 293 cells and p53 expression in FAD-affected brains. Thus our study shows that AICDs control p53 at a transcriptional level, in vitro and in vivo, and that FAD mutations increase p53 expression and activity in cells and human brains.

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Papers by J. Sevalle