Discovery of a novel and highly selective JAK3 inhibitor as a potent hair growth promoter

JAK-STAT signalling pathway inhibitors have emerged as promising therapeutic agents for the treatment of hair loss. Among different JAK isoforms, JAK3 has become an ideal target for drug discovery because it only regulates a narrow spectrum of γc cytokines. Here, we report the discovery of MJ04, a novel and highly selective 3-pyrimidinylazaindole based JAK3 inhibitor, as a potential hair growth promoter with an IC50 of 2.03 nM. During in vivo efficacy assays, topical application of MJ04 on DHT-challenged AGA and athymic nude mice resulted in early onset of hair regrowth. Furthermore, MJ04 significantly promoted the growth of human hair follicles under ex-vivo conditions. MJ04 exhibited a reasonably good pharmacokinetic profile and demonstrated a favourable safety profile under in vivo and in vitro conditions. Taken together, we report MJ04 as a highly potent and selective JAK3 inhibitor that exhibits overall properties suitable for topical drug development and advancement to human clinical trials.

Clinical relevance of biomarkers, new therapeutic approaches, and role of post-translational modifications in the pathogenesis of Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disorder that causes progressive loss of cognitive functions like thinking, memory, reasoning, behavioral abilities, and social skills thus affecting the ability of a person to perform normal daily functions independently. There is no definitive cure for this disease, and treatment options available for the management of the disease are not very effective as well. Based on histopathology, AD is characterized by the accumulation of insoluble deposits of amyloid beta (Aβ) plaques and neurofibrillary tangles (NFTs). Although several molecular events contribute to the formation of these insoluble deposits, the aberrant post-translational modifications (PTMs) of AD-related proteins (like APP, Aβ, tau, and BACE1) are also known to be involved in the onset and progression of this disease. However, early diagnosis of the disease as well as the development of effective therapeutic approaches is impeded by lack of proper clinical biomarkers. In this review, we summarized the current status and clinical relevance of biomarkers from cerebrospinal fluid (CSF), blood and extracellular vesicles involved in onset and progression of AD. Moreover, we highlight the effects of several PTMs on the AD-related proteins, and provide an insight how these modifications impact the structure and function of proteins leading to AD pathology. Finally, for disease-modifying therapeutics, novel approaches, and targets are discussed for the successful treatment and management of AD.

Identification of a stretch of four discontinuous amino acids involved in regulating kinase activity of IGF1R

IGF1R is pursued as a therapeutic target because of its abnormal expression in various cancers. Recently, we reported the presence of a putative allosteric inhibitor binding pocket in IGF1R that could be exploited for developing novel anti-cancer agents. In this study, we examined the role of nine highly conserved residues surrounding this binding pocket with the aim to screen compound libraries in order to develop small molecule allosteric inhibitors of IGF1R. We generated GFP fusion constructs of these mutants to analyze their impact on subcellular localization, kinase activity as well as downstream signalling of IGF1R. K1055H and E1056G were seen to completely abrogate the kinase activity of IGF1R whereas R1064K and L1065A were seen to significantly reduce the IGF1R activity as well. During molecular dynamics analysis, various structural and conformational changes were observed in different conserved regions of mutant proteins particularly in the activation loop resulting in compromising kinase activity of IGF1R. These results show that a stretch of four discontinuous residues within this newly identified binding pocket is critical for activity as well as the structural integrity of IGF1R.

Analyzing structural differences between insulin receptor (IR) and IGF1R for designing small molecule allosteric inhibitors of IGF1R as novel anti-cancer agents

IR and insulin-like growth factor-1 receptor (IGF-1R) share high degree of sequence and structural similarity that hinders the development of anticancer drugs targeting IGF1R, which is dysregulated in many cancers. Although IR and IGF1R mediate their activities through similar signalling pathways, yet they show different physiological effects. The exact molecular mechanism(s) how IR and IGF1R exert their distinct functions remain largely unknown. Here, we performed in silico analysis and generated GFP-fusion proteins of wild type IR and its K1079R mutant to analyze their subcellular localization, cytoplasmic and nuclear activities in comparison to IGF1R and its K1055R mutant. We showed that, like K1055R mutation in IGF1R, K1079R mutation does not impede the subcellular localization and nuclear activities of IR. Although K1079R mutation significantly decreases the kinase activity of IR but not as much as K1055R mutation, which was seen to drastically reduce the kinase activity of IGF1R. Moreover, K1079 residue in IR is seen to be sitting in a pocket which is different than the allosteric inhibitor binding pocket present in its homologue (IGF1R). This is for the first time such a study has been conducted to identify structural differences between these receptors that could be exploited for designing small molecule allosteric inhibitor(s) of IGF1R as novel anti-cancer drugs.