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

• Published in: Bioorganic & medicinal chemistry Vol. 21; no. 4; pp. 1018 - 1029
• Main Authors: Peuchmaur, Marine, Lacour, Marie-Agnès, Sévalle, Jean, Lisowski, Vincent, Touati-Jallabe, Youness, Rodier, Fabien, Martinez, Jean, Checler, Frédéric, Hernandez, Jean-François
• Format: Journal Article
• Language: English
• Published: OXFORD Elsevier Ltd 15.02.2013; Elsevier
• Subjects: Alzheimer’s disease; amyloid; Amyloid beta-Peptides; Amyloid beta-Peptides - metabolism; Amyloid beta-Protein Precursor; Amyloid beta-Protein Precursor - genetics; Amyloid beta-Protein Precursor - metabolism; Amyloid Precursor Protein Secretases; Amyloid Precursor Protein Secretases - genetics; Amyloid Precursor Protein Secretases - metabolism; Amyloid β peptide; Biochemistry & Molecular Biology; Boronic Acids; Boronic Acids - chemistry; Chemical Sciences; Chemistry; Chemistry, Medicinal; Chemistry, Organic; HEK293 Cells; Humans; inhibitory concentration 50; Isocoumarin; Isocoumarins; Isocoumarins - chemical synthesis; Isocoumarins - chemistry; Isocoumarins - metabolism; Life Sciences & Biomedicine; mechanism of action; Pharmacology & Pharmacy; Physical Sciences; proteinase inhibitors; Science & Technology; serine; Serine Proteases; Serine Proteases - metabolism; serine proteinases; structure-activity relationships; Transfection; urethane; γ-Secretase; APP; PS; DMSO; RIPA; TFA; γ-Secretase; Aβ; HRMS; LDH; THF; FBS; AICD; ESI; GSI; EtOAc; GSM; PBS; Amyloid β peptide; Isocoumarin; Alzheimer’s disease; Serine proteases; SDS–PAGE; DCM; HEK; LC/MS; NICD; GSAP; Hex; BACE; PRESENILIN; 3-ALKOXY-7-AMINO-4-CHLOROISOCOUMARINS; MECHANISM; ALZHEIMERS-DISEASE; LEUKOCYTE ELASTASE; PEPTIDE; gamma-Secretase; IN-VITRO; PANCREATIC ELASTASE; 7-AMINO SUBSTITUENT; Amyloid beta peptide; Alzheimer's disease; ISOCOUMARIN-BASED INHIBITORS
• ISSN: 0968-0896; 0960-894X; 1464-3391
• DOI: 10.1016/j.bmc.2012.11.045

The 3-alkoxy-7-amino-4-chloro-isocoumarins JLK-6 and JLK-2 have been shown to markedly reduce the production of Amyloid β-peptide (Aβ) by Amyloid-β Precursor Protein (APP) expressing HEK293 cells by affecting the γ-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 γ-secretase complex but more likely interfere with an upstream target involved in γ-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 Aβ-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 IC50 between 10 and 30μM. Finally, we also explored peptide boronates, a series of reversible serine protease inhibitors, previously shown to also lower cellular Aβ production. The presented data suggested they could act on the same target or interfere with the same pathway as isocoumarins derivatives.