Rational discovery of a SOD1 tryptophan oxidation inhibitor with therapeutic potential for amyotrophic lateral sclerosis.

Formation of Cu, Zn superoxide dismutase 1 (SOD1) protein inclusions within motor neurons is one of the principal characteristics of SOD1-related amyotrophic lateral sclerosis (ALS). A hypothesis as to the nature of SOD1 aggregation implicates oxidative damage to a solvent-exposed tryptophan as causative. Here, we chart the discovery of a phenanthridinone based compound (Lig9) from the NCI Diversity Set III by rational methods by in silico screening and crystallographic validation. The crystal structure of the complex with SOD1, refined to 2.5 Å, revealed that Lig9 binds the SOD1 ß-barrel in the ß-strand 2 and 3 region which is known to scaffold SOD1 fibrillation. The phenanthridinone moiety makes a substantial π-π interaction with Trp32 of SOD1. The compound possesses a significant binding affinity for SOD1 and inhibits oxidation of Trp32; a critical residue for SOD1 aggregation. Thus, Lig9 is a good candidate from which to develop a new library of SOD1 aggregation inhibitors through protection of Trp32 oxidation. Communicated by Ramaswamy H. Sarma.

A facile consensus ranking approach enhances virtual screening robustness and identifies a cell-active DYRK1α inhibitor.

BACKGROUND: Virtual screening is vital for contemporary drug discovery but striking performance fluctuations are commonly encountered, thus hampering error-free use. Results and Methodology: A conceptual framework is suggested for combining screening algorithms characterized by orthogonality (docking-scoring calculations, 3D shape similarity, 2D fingerprint similarity) into a simple, efficient and expansible python-based consensus ranking scheme. An original experimental dataset is created for comparing individual screening methods versus the novel approach. Its utilization leads to identification and phosphoproteomic evaluation of a cell-active DYRK1α inhibitor. CONCLUSION: Consensus ranking considerably stabilizes screening performance at reasonable computational cost, whereas individual screens are heavily dependent on calculation settings. Results indicate that the novel approach, currently available as a free online tool, is highly suitable for prospective screening by nonexperts.

Combined Virtual and Experimental Screening for CK1 Inhibitors Identifies a Modulator of p53 and Reveals Important Aspects of in Silico Screening Performance.

A compound collection of pronounced structural diversity was comprehensively screened for inhibitors of the DNA damage-related kinase CK1. The collection was evaluated in vitro. A potent and selective CK1 inhibitor was discovered and its capacity to modulate the endogenous levels of the CK1-regulated tumor suppressor p53 was demonstrated in cancer cell lines. Administration of 10 µM of the compound resulted in significant increase of p53 levels, reaching almost 2-fold in hepatocellular carcinoma cells. In parallel to experimental screening, two representative and orthogonal in silico screening methodologies were implemented for enabling the retrospective assessment of virtual screening performance on a case-specific basis. Results showed that both techniques performed at an acceptable and fairly comparable level, with a slight advantage of the structure-based over the ligand-based approach. However, both approaches demonstrated notable sensitivity upon parameters such as screening template choice and treatment of redundancy in the enumerated compound collection. An effort to combine insight derived by sequential implementation of the two methods afforded poor further improvement of screening performance. Overall, the presented assessment highlights the relation between improper use of enrichment metrics and misleading results, and demonstrates the inherent delicacy of in silico methods, emphasizing the challenging character of virtual screening protocol optimization.