Progress on the Pharmacological Targeting of Janus Pseudokinases

An overview of small-molecule agents for the treatment of psoriasis

Psoriasis is a prevalent, chronic inflammatory disease characterized by abnormal skin plaques. To date, physical therapy, topical therapy, systemic therapy and biologic drugs are the most commonly employed strategies for treating psoriasis. Recently, many agents have advanced to clinical trials, and some anti-psoriasis drugs have been approved, including antibody drugs and small-molecule drugs. Many antibody drugs targeting cytokines and receptors, such as interleukin (IL-17 and IL-23) and tumor necrosis factor-α (TNF-α), have been approved for the treatment of psoriasis. And numerous small-molecule agents have displayed promising activities in the treatment of psoriasis. The targets of anti-psoriasis drugs encompass phosphodiesterase IV (PDE4), Janus kinase (JAK), tyrosine kinase (TYK), retinoic acid-related orphan receptors (ROR), vitamin D receptor (VDR), Interleukin (IL), Aryl hydrocarbon receptor (AhR), Interleukin-1 receptor-associated kinase 4 (IRAK), chemoattractant-like receptor 1 (ChemR23), Sphingosine-1-phosphate receptor (S1P), A3 adenosine receptor (A3AR), Heat shock protein 90 (HSP90), The Rho-associated protein kinases (ROCK), The bromodomain and extra-terminal domain (BET), FMS-like tyrosine kinase 3 (FLT3), Tumor Necrosis Factor α Converting Enzyme (TACE), Toll-like receptors (TLR), NF-κB inducing kinase (NIK), DNA topoisomerase I (Topo I), among others. Herein, this review mainly recapitulates the advancements in the structure and enzyme activity of small-molecule anti-psoriasis agents over the last ten years, and their binding modes were also explored. Hopefully, this review will facilitate the development of novel small-molecule agents as potential anti-psoriasis drugs.

Molecular basis of JAK kinase regulation guiding therapeutic approaches: Evaluating the JAK3 pseudokinase domain as a drug target

Janus kinases (JAK1-3, TYK2) are critical mediators of cytokine signaling and their role in hematological and inflammatory and autoimmune diseases has sparked widespread interest in their therapeutic targeting. JAKs have unique tandem kinase structure consisting of an active tyrosine kinase domain adjacent to a pseudokinase domain that is a hotspot for pathogenic mutations. The development of JAK inhibitors has focused on the active kinase domain and the developed drugs have demonstrated good clinical efficacy but due to off-target inhibition cause also side-effects and carry a black box warning limiting their use. Our understanding of the regulatory function of the pseudokinase domain in physiological and pathological signaling has improved substantially. The pseudokinase domain maintains the inactive state of JAKs in the absence of cytokine stimulation but it has also a key role in physiological and mutation-driven activation process. Furthermore, the pseudokinase domain has favourable structural characteristics for selective targeting of cytokine signaling, such as unique mode of ATP-binding, and the first pseudokinase targeting inhibitor for TYK2 has been approved for clinical use. Here we describe the recent functional and structural knowledge of JAK signaling and their therapeutic targeting, and present data evaluating the druggability of the JAK3 pseudokinase domain.

Computational insights into rational design and virtual screening of pyrazolopyrimidine derivatives targeting Janus kinase 3 (JAK3)

The Janus kinase 3 (JAK3) family, particularly JAK3, is pivotal in initiating autoimmune diseases such as rheumatoid arthritis. Recent advancements have focused on developing antirheumatic drugs targeting JAK3, leading to the discovery of novel pyrazolopyrimidine-based compounds as potential inhibitors. This research employed covalent docking, ADMET (Absorption, Distribution, Metabolism, Excretion, Toxicity) analysis, molecular dynamics modeling, and MM/GBSA (Molecular Mechanics Generalized Born Surface Area) binding free energy techniques to screen 41 in silico-designed pyrazolopyrimidine derivatives. Initially, 3D structures of the JAK3 enzyme were generated using SWISS-MODEL, followed by virtual screening and covalent docking via AutoDock4 (AD4). The selection process involved the AMES test, binding affinity assessment, and ADMET analysis, narrowing down the candidates to 27 compounds that passed the toxicity test. Further covalent docking identified compounds 21 and 41 as the most promising due to their high affinity and favourable ADMET profiles. Subsequent development led to the creation of nine potent molecules, with derivatives 43 and 46 showing exceptional affinity upon evaluation through molecular dynamics simulation and MM/GBSA calculations over 300 nanoseconds, comparable to tofacitinib, an approved RA drug. However, compounds L21 and L46 demonstrated stable performance, suggesting their effectiveness in treating rheumatoid arthritis and other autoimmune conditions associated with JAK3 inhibition.

Revisiting Structure-activity Relationships: Unleashing the potential of selective Janus kinase 1 inhibitors

Janus kinases (JAKs), a kind of non-receptor tyrosine kinases, the function has been implicated in the regulation of cell proliferation, differentiation and apoptosis, immune, inflammatory response and malignancies. Among them, JAK1 represents an essential target for modulating cytokines involved in inflammation and immune function. Rheumatoid arthritis, atopic dermatitis, ulcerative colitis and psoriatic arthritis are areas where approved JAK1 drugs have been applied for the treatment. In the review, we provided a brief introduction to JAK1 inhibitors in market and clinical trials. The structures of high active JAK1 compounds (IC50 ≤ 0.1 nM) were highlighted, with primary focus on structure-activity relationship and selectivity. Moreover, the druggability processes of approved drugs and high active compounds were analyzed. In addition, the issues involved in JAK1 compounds clinical application as well as strategies to surmount these challenges, were discussed.

Revealing innovative JAK1 and JAK3 inhibitors: a comprehensive study utilizing QSAR, 3D-Pharmacophore screening, molecular docking, molecular dynamics, and MM/GBSA analyses

The heterocycle compounds, with their diverse functionalities, are particularly effective in inhibiting Janus kinases (JAKs). Therefore, it is crucial to identify the correlation between their complex structures and biological activities for the development of new drugs for the treatment of rheumatoid arthritis (RA) and cancer. In this study, a diverse set of 28 heterocyclic compounds selective for JAK1 and JAK3 was employed to construct quantitative structure-activity relationship (QSAR) models using multiple linear regression (MLR). Artificial neural network (ANN) models were employed in the development of QSAR models. The robustness and stability of the models were assessed through internal and external methodologies, including the domain of applicability (DoA). The molecular descriptors incorporated into the model exhibited a satisfactory correlation with the receptor-ligand complex structures of JAKs observed in X-ray crystallography, making the model interpretable and predictive. Furthermore, pharmacophore models ADRRR and ADHRR were designed for each JAK1 and JAK3, proving effective in discriminating between active compounds and decoys. Both models demonstrated good performance in identifying new compounds, with an ROC of 0.83 for the ADRRR model and an ROC of 0.75 for the ADHRR model. Using a pharmacophore model, the most promising compounds were selected based on their strong affinity compared to the most active compounds in the studied series each JAK1 and JAK3. Notably, the pharmacokinetic, physicochemical properties, and biological activities of the selected compounds (As compounds ZINC79189223 and ZINC66252348) were found to be consistent with their therapeutic effects in RA, owing to their non-toxic, cholinergic nature, absence of P-glycoprotein, high gastrointestinal absorption, and ability to penetrate the blood-brain barrier. Furthermore, ADMET properties were assessed, and molecular dynamics and MM/GBSA analysis revealed stability in these molecules.