Drugs That Regulate Local Cell Signaling: AKAP Targeting as a Therapeutic Option.

Cells respond to environmental cues by mobilizing signal transduction cascades that engage protein kinases and phosphoprotein phosphatases. Correct organization of these enzymes in space and time enables the efficient and precise transmission of chemical signals. The cyclic AMP-dependent protein kinase A is compartmentalized through its association with A-kinase anchoring proteins (AKAPs). AKAPs are a family of multivalent scaffolds that constrain signaling enzymes and effectors at subcellular locations to drive essential physiological events. More recently, it has been recognized that defective signaling in certain endocrine disorders and cancers proceeds through pathological AKAP complexes. Consequently, pharmacologically targeting these macromolecular complexes unlocks new therapeutic opportunities for a growing number of clinical indications. This review highlights recent findings on AKAP signaling in disease, particularly in certain cancers, and offers an overview of peptides and small molecules that locally regulate AKAP-binding partners.

Gravin-associated kinase signaling networks coordinate γ-tubulin organization at mitotic spindle poles.

Mitogenic signals that regulate cell division often proceed through multienzyme assemblies within defined intracellular compartments. The anchoring protein Gravin restricts the action of mitotic kinases and cell-cycle effectors to defined mitotic structures. In this report we discover that genetic deletion of Gravin disrupts proper accumulation and asymmetric distribution of γ-tubulin during mitosis. We utilize a new precision pharmacology tool, Local Kinase Inhibition, to inhibit the Gravin binding partner polo-like kinase 1 at spindle poles. Using a combination of gene-editing approaches, quantitative imaging, and biochemical assays, we provide evidence that disruption of local polo-like kinase 1 signaling underlies the γ-tubulin distribution defects observed with Gravin loss. Our study uncovers a new role for Gravin in coordinating γ-tubulin recruitment during mitosis and illuminates the mechanism by which signaling enzymes regulate this process at a distinct subcellular location.

Subcellular drug targeting illuminates local kinase action.

Deciphering how signaling enzymes operate within discrete microenvironments is fundamental to understanding biological processes. A-kinase anchoring proteins (AKAPs) restrict the range of action of protein kinases within intracellular compartments. We exploited the AKAP targeting concept to create genetically encoded platforms that restrain kinase inhibitor drugs at distinct subcellular locations. Local Kinase Inhibition (LoKI) allows us to ascribe organelle-specific functions to broad specificity kinases. Using chemical genetics, super resolution microscopy, and live-cell imaging we discover that centrosomal delivery of Polo-like kinase 1 (Plk1) and Aurora A (AurA) inhibitors attenuates kinase activity, produces spindle defects, and prolongs mitosis. Targeted inhibition of Plk1 in zebrafish embryos illustrates how centrosomal Plk1 underlies mitotic spindle assembly. Inhibition of kinetochore-associated pools of AurA blocks phosphorylation of microtubule-kinetochore components. This versatile precision pharmacology tool enhances investigation of local kinase biology.

Behavioral and pharmacological evaluation of a selectively bred mouse model of home cage hyperactivity.

Daily levels of physical activity vary greatly across individuals and are strongly influenced by genetic background. While moderate levels of physical activity are associated with improved physical and mental health, extremely high levels of physical activity are associated with behavioral disorders such as attention deficit hyperactivity disorder (ADHD). However, the genetic and neurobiological mechanisms relating hyperactivity to ADHD or other behavioral disorders remain unclear. Therefore, we conducted a selective breeding experiment for increased home cage activity starting with a highly genetically variable population of house mice and evaluated the line for correlated responses in other relevant phenotypes. Here we report results through Generation 10. Relative to the Control line, the High-Active line traveled approximately 4 times as far in the home cage (on days 5 and 6 of a 6-day test), displayed reduced body mass at maturity, reduced reproductive success, increased wheel running and open field behavior, decreased performance on the rotarod, decreased performance on the Morris water maze that was not rescued by acute administration of d-amphetamine, reduced hyperactivity from chronically administered low clinical doses of d-amphetamine, and increased numbers of new cells and neuronal activation of the dentate gyrus. Standardized phenotypic differences between the lines were compared to estimates expected from genetic drift to evaluate whether the line differences could have resulted from random effects as opposed to correlated responses to selection. Results indicated line differences in body mass and locomotor responses to low doses of amphetamine were more likely due to selection than drift. The efficacy of low doses of d-amphetamine in ameliorating hyperactivity support the High-Active line as a useful model for exploring the etiology of hyperactivity-associated comorbid behavioral disorders.