Ischemic stroke is the 5th leading cause of death in the United States. Despite significant improvements in reperfusion therapies, stroke patients still suffer from debilitating neurocognitive deficits. This indicates an essential need to develop novel stroke treatment paradigms. Endogenous uptake transporters expressed at the blood-brain barrier (BBB) provide an excellent opportunity to advance stroke therapy via optimization of small molecule neuroprotective drug delivery to the brain. Examples of such uptake transporters include organic anion transporting polypeptides (OATPs in humans; Oatps in rodents) and organic cation transporters (OCTs in humans; Octs in rodents). Of particular note, small molecule drugs that have neuroprotective properties are known substrates for these transporters and include 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (i.e., statins) for OATPs/Oatps and 1-amino-3,5-dimethyladamantane (i.e., memantine) for OCTs/Octs. Here, we review current knowledge on specific BBB transporters that can be targeted for improvement of ischemic stroke treatment and provide state-of-the-art perspectives on the rationale for considering BBB transport properties during discovery/development of stroke therapeutics.

Globally, stroke is a leading cause of death and long-term disability. Over the past decades, several efforts have attempted to discover new drugs or repurpose existing therapeutics to promote post-stroke neurological recovery. Preclinical stroke studies have reported successes in identifying novel neuroprotective agents; however, none of these compounds have advanced beyond a phase III clinical trial. One reason for these failures is the lack of consideration of blood–brain barrier (BBB) transport mechanisms that can enable these drugs to achieve efficacious concentrations in ischemic brain tissue. Despite the knowledge that drugs with neuroprotective properties (i.e., statins, memantine, metformin) are substrates for endogenous BBB transporters, preclinical stroke research has not extensively studied the role of transporters in central nervous system (CNS) drug delivery. Here, we review current knowledge on specific BBB uptake transporters (i.e., organic anion transporting polypeptides (OATPs in humans; Oatps in rodents); organic cation transporters (OCTs in humans; Octs in rodents) that can be targeted for improved neuroprotective drug delivery. Additionally, we provide state-of-the-art perspectives on how transporter pharmacology can be integrated into preclinical stroke research. Specifically, we discuss the utility of in vivo stroke models to transporter studies and considerations (i.e., species selection, co-morbid conditions) that will optimize the translational success of stroke pharmacotherapeutic experiments.

Desmoplakin (DP) is an obligate component of desmosomal cellecell junctions that links the adhesion plaque to the cytoskeletal intermediate filament network. While a central role for DP in maintaining the structure and stability of the desmosome is well established, recent work has indicated that DP's functions may extend beyond cellecell adhesion. In our study, we show that loss of DP results in a significant increase in cellular migration, as measured by scratch wound assays, Transwell migration assays, and invasion assays. Loss of DP causes dramatic changes in actin cytoskeleton morphology, including enhanced protrusiveness, and an increase in filopodia length and number. Interestingly, these changes are also observed in single cells, indicating that control of actin morphology is a cellecell adhesion-independent function of DP. An investigation of cellular signaling pathways uncovered aberrant Rac and p38 mitogen-activated protein kinase (MAPK) activity in DP knockdown cells, restoration of which is sufficient to rescue DP-dependent changes in both cell migration and actin cytoskeleton morphology. Taken together, these data highlight a previously uncharacterized role for the desmosomal cytolinker DP in coordinating cellular migration via p38 MAPK and Rac signaling.

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