ADHD-associated PARK2 copy number variants: A pilot study on gene expression and effects of supplementary deprivation in patient-derived cell lines.

Recent studies show an association of Parkin RBR E3 ubiquitin protein ligase (PARK2) copy number variations (CNVs) with attention deficit hyperactivity disorder (ADHD). The aim of our pilot study to investigate gene expression associated with PARK2 CNVs in human-derived cellular models. We investigated gene expression in fibroblasts, hiPSC and dopaminergic neurons (DNs) of ADHD PARK2 deletion and duplication carriers by qRT PCR compared with healthy and ADHD cell lines without PARK2 CNVs. The selected 10 genes of interest were associated with oxidative stress response (TP53, NQO1, and NFE2L2), ubiquitin pathway (UBE3A, UBB, UBC, and ATXN3) and with a function in mitochondrial quality control (PINK1, MFN2, and ATG5). Additionally, an exploratory RNA bulk sequencing analysis in DNs was conducted. Nutrient deprivation as a supplementary deprivation stress paradigm was used to enhance potential genotype effects. At baseline, in fibroblasts, hiPSC, and DNs, there was no significant difference in gene expression after correction for multiple testing. After nutrient deprivation in fibroblasts NAD(P)H-quinone-dehydrogenase 1 (NQO1) expression was significantly increased in PARK2 CNV carriers. In a multivariate analysis, ubiquitin C (UBC) was significantly upregulated in fibroblasts of PARK2 CNV carriers. RNA sequencing analysis of DNs showed the strongest significant differential regulation in Neurontin (NNAT) at baseline and after nutrient deprivation. Our preliminary results suggest differential gene expression in pathways associated with oxidative stress, ubiquitine-proteasome, immunity, inflammation, cell growth, and differentiation, excitation/inhibition modulation, and energy metabolism in PARK2 CNV carriers compared to wildtype healthy controls and ADHD patients.

Michael acceptor based antiplasmodial and antitrypanosomal cysteine protease inhibitors with unusual amino acids.

New peptidic Michael acceptor based cysteine protease inhibitors displaying antiparasitic activity were identified by testing a broad series of 45 compounds in total, containing Asn, Gln, or Phe. As target enzymes, falcipain-2 and -3 from P. falciparum and rhodesain from T. b. rhodesiense were used. In the case of the Asn/Gln containing compounds, the trityl-protected, diastereomeric E-configured vinylogous dipeptide esters 16 (Boc-(S)-Phg-(R/S)-vGln(Trt)-OEt) were discovered as most active inhibitors concerning both protease inhibition and antiparasitic acitivity, with inhibition constants in the submicromolar range. The compounds were shown to display time-dependent and competitive inhibition. In the case of the Phe containing compounds, the maleic acid derivatives 42 and 43 (BnO-Phe<--Mal-Phe-OBn, BnO-Phe<--Mal-Phe-Ala-OBn, Mal = maleic acid) displayed good inhibition of rhodesain as well as good antitrypanosomal activity, while the fumaric acid derived E-analogue 14 (BnO-Phe<--Fum-Phe-OBn) only displayed inhibition of the target enzymes but no antiparasitic activity. Inhibition by these Phe derivatives was shown to be time-independent and competitive.

On-bead screening of a combinatorial fumaric acid derived peptide library yields antiplasmodial cysteine protease inhibitors with unusual peptide sequences.

A new class of cysteine protease inhibitors based on fumaric acid derived oligopeptides was successfully identified from a high-throughput screening of a solid-phase bound combinatorial library. As target enzymes falcipain and rhodesain were used, which play important roles in the life cycles of the parasites which cause malaria (Plasmodium falciparum) and African sleeping sickness (Trypanosoma brucei rhodesiense). The best inhibitors with unusual amino acid sequences not reported before for this type of enzyme were also fully analyzed in detail in solution. K(i) values in the lower micromolar and even nanomolar region were found. Some inhibitors are even active against plasmodia and show good selectivity relative to other enzymes. Also the mechanism of action was studied and could be shown to be irreversible inhibition.