Highlights d mGlu 2 and mGlu 3 negative allosteric modulators (NAMs) stimulate prefrontal cortex d mGlu 2 regulates thalamocortical glutamate release probability d mGlu 3 directs prefrontal cortex postsynaptic plasticity d mGlu 2 and mGlu 3 NAMs independently decrease passive coping and reverse anhedonia

Engagement of integrins by the extracellular matrix initiates signaling cascades that drive a variety of cellular functions, including neuronal migration and axonal pathfinding in the brain. Multiple lines of evidence link the ITGB3 gene encoding the integrin ␤3 subunit with the serotonin (5-HT) system, likely via its modulation of the 5-HT transporter (SERT). The ITGB3 coding polymorphism Leu33Pro (rs5918, Pl A2 ) produces hyperactive ␣v␤3 receptors that influence whole-blood 5-HT levels and may influence the risk for autism spectrum disorder (ASD). Using a phenome-wide scan of psychiatric diagnoses, we found significant, male-specific associations between the Pro33 allele and attention-deficit hyperactivity disorder and ASDs. Here, we used knock-in (KI) mice expressing an Itgb3 variant that phenocopies the human Pro33 variant to elucidate the consequences of constitutively enhanced ␣v␤3 signaling to the 5-HT system in the brain. KI mice displayed deficits in multiple behaviors, including anxiety, repetitive, and social behaviors. Anatomical studies revealed a significant decrease in 5-HT synapses in the midbrain, accompanied by decreases in SERT activity and reduced localization of SERTs to integrin adhesion complexes in synapses of KI mice. Inhibition of focal adhesion kinase (FAK) rescued SERT function in synapses of KI mice, demonstrating that constitutive active FAK signaling downstream of the Pro32Pro33 integrin ␣v␤3 suppresses SERT activity. Our studies identify a complex regulation of 5-HT homeostasis and behaviors by integrin ␣v␤3, revealing an important role for integrins in modulating risk for neuropsychiatric disorders.

Reduced platelet aggregation and a mild bleeding phenotype have been observed in patients chronically taking selective serotonin reuptake inhibitors (SSRIs). However, it remains unclear how SSRIs, which inhibit the plasma membrane serotonin transporter (SERT), modulate hemostasis. Here, we examine how sustained inhibition of SERT activity alters serotonergic signaling and influences platelet activation and hemostasis. In the periphery, serotonin (5-HT) 3 is produced by enterochromaffin cells in the gastrointestinal tract, released into the plasma, and quickly taken up by platelets via the plasma membrane serotonin transporter (SERT). Following uptake, 5-HT is stored in dense granules by the actions of the vesicular monoamine transporter 2 (1-4). Chronic inhibition of SERT through selective serotonin reuptake inhibitors (SSRIs) (e.g. citalopram and paroxetine) leads to dramatically reduced platelet 5-HT granule content (5, 6), altering peripheral 5-HT homeostasis and potentially modifying multiple physiological processes including hemostasis (7-10). Clinically, increased bleeding risk has been observed in patients taking SSRIs, and platelet aggregation is disrupted (5, 11). Here, we have characterized a similar effect in two distinct mouse models of lost SERT function, suggesting that sustained loss of SERT function influences hemostasis. Pharmaceutical blockade (citalopram dosing) or genetic ablation (SERTPlatelet dense granules contain 5-HT along with other platelet agonists including adenosine diphosphate (ADP), thromboxane (TXA2), and histamine. Appropriate platelet activation depends on the timely release of these factors (4, 5, 12). Platelet aggregation is crucial early in thrombus formation (4, 5, 13). Aggregation, which is the bridging of platelet-platelet contacts, requires a conformational alteration in the glycoprotein ␣IIb␤3, leading to its activation and fibrinogen binding. 5-HT has been shown to enhance aggregation in a 5-HT 2A receptor (5-HT 2A R)-dependent manner (4, 14 -17). The 5-HT 2A R is the only serotonergic receptor found on platelets and potentiates platelet responses to weak agonists like ADP (18). Subthreshold concentrations of two different platelet agonists can exert a synergistic effect on platelet activation. One example includes dual ADP and 5-HT activation leading to increases in cytosolic [Ca 2ϩ ] (13). However, the role of 5-HT during in vivo hemostasis remains unclear, particularly in the context of chronic SERT inhibition.To elucidate the underlying mechanisms of SSRI effects on platelet aggregation, a better understanding of acute versus chronic inhibition of SERT function during platelet activation is required. Acute and chronic blockage of SERT function results in distinct scenarios regarding the effects on 5-HT homeostasis. Acute inhibition of SERT blocks the amount of

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The plasma-membrane integrin aIIbb 3 (CD41/CD61, GPIIbIIIa) is a major functional receptor in platelets during clotting. A common isoform of integrin b 3 , Leu33Pro is associated with enhanced platelet function and increased risk for coronary thrombosis and stroke, although these findings remain controversial. To better understand the molecular mechanisms by which this sequence variation modifies platelet function, we produced transgenic knockin mice expressing a Pro32Pro33 integrin b 3 . Consistent with reports utilizing human platelets, we found significantly reduced bleeding and clotting times, as well as increased in vivo thrombosis, in Pro32Pro33 homozygous mice. These alterations paralleled increases in platelet attachment and spreading onto fibrinogen resulting from enhanced integrin aIIbb 3 function. Activation with protease-activated receptor 4-activating peptide, the main thrombin signaling receptor in mice, showed no significant difference in activation of Pro32Pro33 mice as compared with controls, suggesting that inside-out signaling remains intact. However, under unstimulated conditions, the Pro32Pro33 mutation led to elevated Src phosphorylation, facilitated by increased talin interactions with the b 3 cytoplasmic domain, indicating that the aIIbb 3 intracellular domains are primed for activation while the ligand-binding domain remains unchanged. Acute dosing of animals with a Src inhibitor was sufficient to rescue the clotting phenotype in knockin mice to wild-type levels. Together, our data establish that the Pro32Pro33 structural alteration modifies the function of integrin aIIbb 3 , priming the integrin for outside-in signaling, ultimately leading to hypercoagulability. Furthermore, our data may support a novel approach to antiplatelet therapy by Src inhibition where hemostasis is maintained while reducing risk for cardiovascular disease.

A "how-to" guide for producing videos, bridging multimedia learning theory with a production pipeline. Three steps in contemporary video-making for educational purposes are outlined: preproduction, production, and postproduction. Overall, the article encourages educators to become producers by engaging in this creative medium.

Due to COVID-19 precautions, the Vanderbilt University summer biomedical undergraduate research program, the Vanderbilt Summer Science Academy (VSSA), rapidly transitioned from offering an in-person training program to a virtual seminar format. Our program typically supports undergraduate development through research and/or clinical experience, meeting with individuals pursuing postgraduate training, and providing career development advice. Evidence supports the idea that summer programs transform undergraduates by clarifying their interest in research and encouraging those who haven’t previously considered graduate studies. We were interested in exploring whether a virtual, synchronous program would increase participants’ scientific identity and clarify postgraduate career planning. Rather than create a virtual research exposure, our 5-week "Virtual VSSA" program aimed to simulate the casual connections that would naturally be made with post-undergraduate trainees during a traditional summer program. In seminars, presenters discussed 1) their academic journey, explaining their motivations, goals, and reasons for pursuing a career in science as well as 2) a professional story that illustrated their training. Seminars included Vanderbilt University and Medical School faculty, M.D., MD/Ph.D., as well as Ph.D. students from diverse scientific and personal backgrounds. In addition, weekly informational sessions provided an overview of the nature of each degree program along with admissions advice. Through pre-and post-program surveys, we found that students who registered for this experience already strongly identified with the STEMM community (Science, Technology, Engineering, Mathematics, and Medicine). However, participation in the Virtual VSSA increased their sense of belonging. We also uncovered a gap in participants’ understanding of postgraduate pathways prior to participation and found that our program significantly increased their self-reported understanding of postgraduate programs. It also increased their understanding of why someone would pursue a Ph.D. or Ph.D./MD versus M.D. These changes did not uniformly impact participants’ planned career paths. Overall, by providing personal, tangible stories of M.D., MD/Ph.D., and Ph.D. training, the Virtual VSSA program offered seminars that positively impacted students’ sense of belonging with and connection to the STEMM disciplines.