NMDA receptor-dependent long-term potentiation (LTP) and depression (LTD) are forms of synaptic plasticity underlying learning and memory that are expressed through increases and decreases, respectively, in dendritic spine size and AMPA receptor (AMPAR) phosphorylation and postsynaptic localization. The A-kinase anchoring protein 79/150 (AKAP79/150) signaling scaffold regulates AMPAR phosphorylation, channel activity, and endosomal trafficking associated with LTP and LTD. AKAP79/150 is targeted to dendritic spine plasma membranes by an N-terminal polybasic domain that binds phosphoinositide lipids, F-actin, and cadherin cell adhesion molecules. However, we do not understand how regulation of AKAP targeting controls AMPAR endosomal trafficking. Here, we report that palmitoylation of the AKAP N-terminal polybasic domain targets it to postsynaptic lipid rafts and dendritic recycling endosomes. AKAP palmitoylation was regulated by seizure activity in vivo and LTP/LTD plasticity-inducing stimuli in cultured rat hippocampal neurons. With chemical LTP induction, we observed AKAP79 dendritic spine recruitment that required palmityolation and Rab11-regulated endosome recycling coincident with spine enlargement and AMPAR surface delivery. Importantly, a palmitoylation-deficient AKAP79 mutant impaired regulation of spine size, endosome recycling, AMPAR trafficking, and synaptic potentiation. These findings emphasize the emerging importance of palmitoylation in controlling synaptic function and reveal novel roles for the AKAP79/150 signaling complex in dendritic endosomes.

Background Internet-based participation has the potential to enhance pragmatic and decentralized trials, where representative study populations and generalizability to clinical practice are key. We aimed to study the differences between internet and noninternet/telephone participants in a large remote, pragmatic trial. Methods and Results In a subanalysis of the ADAPTABLE (Aspirin Dosing: A Patient-Centric Trial Assessing Benefits and Long-Term Effectiveness) study, we compared internet participants with those who opted for noninternet participation. Study process measures examined included participant characteristics at consent, study medication adherence, and study retention. The clinical outcome examined was a composite of all-cause mortality, hospitalization for myocardial infarction, or hospitalization for stroke. Noninternet participants were older (mean 69.4 versus 67.4 years), more likely to be female (38.9% versus 30.2%), more likely to be Black (27.3% versus 6.0%) or Hispanic (11.1% versus 2.0%), and had a higher number of comorbid conditions. The composite clinical outcome was more than twice as high in noninternet participants. The hazard of nonadherence to the assigned aspirin dosage was 46% higher in noninternet participants than internet participants. Conclusions Noninternet participants differed from internet participants in notable demographic characteristics while having poorer baseline health. Over the course of ADAPTABLE, they also had worse clinical outcomes and greater likelihood of study drug nonadherence. These results suggest that trials focused on internet participation select for younger, healthier participants with a higher proportion of traditionally overrepresented patients. Allowing noninternet participation enhances diversity; however, additional steps may be needed to promote study retention and study medication adherence. Registration Information clinicaltrials.gov. Identifier: NCT02697916.