Myeloid cell-specific deletion of epidermal growth factor receptor aggravates acute cardiac injury.

Myeloid cells, including macrophages, play important roles as first responders to cardiac injury and stress. Epidermal growth factor receptor (EGFR) has been identified as a mediator of macrophage responsiveness to select diseases, though its impact on cardiac function or remodeling following acute ischemic injury is unknown. We aimed to define the role of myeloid cell-specific EGFR in the regulation of cardiac function and remodeling following acute myocardial infarction (MI)-induced injury. Floxed EGFR mice were bred with homozygous LysM-Cre (LMC) transgenic mice to yield myeloid-specific EGFR knockout (mKO) mice. Via echocardiography, immunohistochemistry, RNA sequencing and flow cytometry, the impact of myeloid cell-specific EGFR deletion on cardiac structure and function was assessed at baseline and following injury. Compared with LMC controls, myeloid cell-specific EGFR deletion led to an increase in cardiomyocyte hypertrophy at baseline. Bulk RNASeq analysis of isolated cardiac Cd11b+ myeloid cells revealed substantial changes in mKO cell transcripts at baseline, particularly in relation to predicted decreases in neovascularization. In response to myocardial infarction, mKO mice experienced a hastened decline in cardiac function with isolated cardiac Cd11b+ myeloid cells expressing decreased levels of the pro-reparative mediators Vegfa and Il10, which coincided with enhanced cardiac hypertrophy and decreased capillary density. Overall, loss of EGFR qualitatively alters cardiac resident macrophages that promotes a low level of basal stress and a more rapid decrease in cardiac function along with worsened repair following acute ischemic injury.

Maternal continuous oral oxycodone self-administration alters pup affective/social communication but not spatial learning or sensory-motor function.

BACKGROUND: The broad use/misuse of prescription opioids during pregnancy has resulted in a surge of infants with Neonatal Opioid Withdrawal Syndrome (NOWS). Short-term irritability and neurological complications are its hallmarks, but the long-term consequences are unknown. METHODS: A newly-developed preclinical model of oxycodone self-administration enables adult female rats to drink oxycodone (∼10/mg/kg/day) before and during pregnancy, and after delivery, and to maintain normal liquid intake, titrate dosing, and avoid withdrawal. RESULTS: Oxycodone was detected in the serum of mothers and pups. Growth parameters in dams and pups and litter mass and size were similar to controls. There were no differences in paw retraction latency to a thermal stimulus between Oxycodone and Control pups at postnatal (PN) 2 or PN14. Oxycodone and Control pups had similar motor coordination, cliff avoidance, righting time, pivoting, and olfactory spatial learning from PN3 through PN13. Separation-induced ultrasonic vocalizations at PN8 revealed higher call frequency in Oxycodone pups relative to Control pups (p<0.031; Cohen's d=1.026). Finally, Oxycodone pups displayed withdrawal behaviors (p's<0.029; Cohen's d's>0.806), and Oxycodone males only vocalized more than Control pups in the first minute of testing (p's<0.050; Cohen's d's>.866). Significant effects were corroborated by estimation plots. CONCLUSIONS: Our rat model of oral oxycodone self-administration in pregnancy shows exacerbated affect/social communication in pups in a sex-dependent manner but spared cognition and sensory-motor behaviors. This preclinical model reproduces selective aspects of human opioid use during pregnancy, enabling longitudinal analysis of how maternal oxycodone changes emotional behavior in the offspring.

Epidermal growth factor receptor association with ß1-adrenergic receptor is mediated via its juxtamembrane domain.

ß1-adrenergic receptor (ß1AR)-mediated transactivation of epidermal growth factor receptor (EGFR) engages downstream signaling events that impact numerous cellular processes including growth and survival. While association of these receptors has been shown to occur basally and be important for relaying transactivation-specific intracellular events, the mechanism by which they do so is unclear and elucidation of which would aid in understanding the consequence of disrupting their interaction. Using fluorescence resonance energy transfer (FRET) and immunoprecipitation (IP) analyses, we evaluated the impact of C-terminal truncations of EGFR on its ability to associate with ß1AR. While loss of the last 230 amino acid C-terminal phosphotyrosine-rich domain did not disrupt the ability of EGFR to associate with ß1AR, truncation of the entire intracellular domain of EGFR resulted in almost complete loss of its interaction with ß1AR, suggesting that either the kinase domain or juxtamembrane domain (JMD) may be required for this association. Treatment with the EGFR antagonist gefitinib did not prevent ß1AR-EGFR association, however, treatment with a palmitoylated peptide encoding the first 20 amino acids of the JMD domain (JMD-A) disrupted ß1AR-EGFR association over time and prevented ß1AR-mediated ERK1/2 phosphorylation, both in general and specifically in association with EGFR. Conversely, neither a mutated JMD-A peptide nor a palmitoylated peptide fragment consisting of the subsequent 18 amino acids of the JMD domain (JMD-B) were capable of doing so. Altogether, the proximal region of the JMD of EGFR is responsible for its association with ß1AR, and its disruption prevents ß1AR-mediated transactivation, thus providing a new tool to study the functional consequences of disrupting ß1AR-EGFR downstream signaling.