Discovery of Potent and Brain-Penetrant Tau Tubulin Kinase 1 (TTBK1) Inhibitors that Lower Tau Phosphorylation In Vivo.

Structural analysis of the known NIK inhibitor 3 bound to the kinase domain of TTBK1 led to the design and synthesis of a novel class of azaindazole TTBK1 inhibitors exemplified by 8 (cell IC50: 571 nM). Systematic optimization of this series of analogs led to the discovery of 31, a potent (cell IC50: 315 nM) and selective TTBK inhibitor with suitable CNS penetration (rat Kp,uu: 0.32) for in vivo proof of pharmacology studies. The ability of 31 to inhibit tau phosphorylation at the disease-relevant Ser 422 epitope was demonstrated in both a mouse hypothermia and a rat developmental model and provided evidence that modulation of this target may be relevant in the treatment of Alzheimer's disease and other tauopathies.

The crystal structure of the catalytic domain of tau tubulin kinase 2 in complex with a small-molecule inhibitor.

Tau proteins play an important role in the proper assembly and function of neurons. Hyperphosphorylation of tau by kinases such as tau tubulin kinase (TTBK) has been hypothesized to cause the aggregation of tau and the formation of neurofibrillary tangles (NFTs) that lead to the destabilization of microtubules, thereby contributing to neurodegenerative diseases such as Alzheimer's disease (AD). There are two TTBK isoforms with highly homologous catalytic sites but with distinct tissue distributions, tau phosphorylation patterns and loss-of-function effects. Inhibition of TTBK1 reduces the levels of NFT formation involved in neurodegenerative diseases such as AD, whereas inhibition of TTBK2 may lead to the movement disorder spinocerebellar ataxia type 11 (SCA11). Hence, it is critical to obtain isoform-selective inhibitors. Structure-based drug design (SBDD) has been used to design highly potent and exquisitely selective inhibitors. While structures of TTBK1 have been reported in the literature, TTBK2 has evaded structural characterization. Here, the first crystal structure of the TTBK2 kinase domain is described. Furthermore, the crystal structure of human TTBK2 in complex with a small-molecule inhibitor has successfully been determined to elucidate the structural differences in protein conformations between the two TTBK isoforms that could aid in SBDD for the design of inhibitors that selectively target TTBK1 over TTBK2.

Addressing Police Occupational Safety During an Opioid Crisis: The Syringe Threat and Injury Correlates (STIC) Score.

OBJECTIVE: To develop and validate syringe threat and injury correlates (STIC) score to measure police vulnerability to needlestick injury (NSI). METHODS: Tijuana police officers (N = 1788) received NSI training (2015 to 2016). STIC score incorporates five self-reported behaviors: syringe confiscation, transportation, breaking, discarding, and arrest for syringe possession. Multivariable logistic regression was used to evaluate the association between STIC score and recent NSI. RESULTS: Twenty-three (1.5%) officers reported NSI; higher among women than men (3.8% vs 1.2%; P = 0.007). STIC variables had high internal consistency, a distribution of 4.0, a mode of 1.0, a mean (sd) of 2.0 (0.8), and a median (interquartile range [IQR]) of 2.0 (1.2 to 2.6). STIC was associated with recent NSI; odds of NSI being 2.4 times higher for each point increase (P-value <0.0001). CONCLUSIONS: STIC score is a novel tool for assessing NSI risk and prevention program success among police.

Germinal-center kinase-like kinase co-crystal structure reveals a swapped activation loop and C-terminal extension.

Germinal-center kinase-like kinase (GLK, Map4k3), a GCK-I family kinase, plays multiple roles in regulating apoptosis, amino acid sensing, and immune signaling. We describe here the crystal structure of an activation loop mutant of GLK kinase domain bound to an inhibitor. The structure reveals a weakly associated, activation-loop swapped dimer with more than 20 amino acids of ordered density at the carboxy-terminus. This C-terminal PEST region binds intermolecularly to the hydrophobic groove of the N-terminal domain of a neighboring molecule. Although the GLK activation loop mutant crystallized demonstrates reduced kinase activity, its structure demonstrates all the hallmarks of an "active" kinase, including the salt bridge between the C-helix glutamate and the catalytic lysine. Our compound displacement data suggests that the effect of the Ser170Ala mutation in reducing kinase activity is likely due to its effect in reducing substrate peptide binding affinity rather than reducing ATP binding or ATP turnover. This report details the first structure of GLK; comparison of its activation loop sequence and P-loop structure to that of Map4k4 suggests ideas for designing inhibitors that can distinguish between these family members to achieve selective pharmacological inhibitors.