Biased signalling is structurally encoded as an autoproteolysis event in adhesion G protein-coupled receptor Latrophilin-3/ADGRL3.

Adhesion G protein-coupled receptors (aGPCRs) possess a unique topology, including the presence of a GPCR proteolysis site (GPS), which, upon autoproteolysis, generates two functionally distinct fragments that remain non-covalently associated at the plasma membrane. A proposed activation mechanism for aGPCRs involves the exposure of a tethered agonist, which depends on cleavage at the GPS. However, this hypothesis has been challenged by the observation that non-cleavable aGPCRs exhibit constitutive activity, thus making the function of GPS cleavage widely enigmatic. In this study, we sought to elucidate the function of GPS-mediated cleavage through the study of G protein coupling with Latrophilin-3/ADGRL3, a prototypical aGPCR involved in synapse formation and function. Using BRET-based G protein biosensors, we reveal that an autoproteolysis-deficient mutant of ADGRL3 retains constitutive activity. Surprisingly, we uncover that cleavage deficiency leads to a signalling bias directed at potentiating the activity of select G proteins such as Gi2 and G12/13. These data unveil the underpinnings of biased signalling for aGPCRs defined by GPS autoproteolysis.

Convergent selective signaling impairment exposes the pathogenicity of latrophilin-3 missense variants linked to inheritable ADHD susceptibility.

Latrophilin-3 (Lphn3; also known as ADGRL3) is a member of the adhesion G Protein Coupled Receptor subfamily, which participates in the stabilization and maintenance of neuronal networks by mediating intercellular adhesion through heterophilic interactions with transmembrane ligands. Polymorphisms modifying the Lphn3 gene are associated with attention-deficit/hyperactivity disorder (ADHD) in children and its persistence into adulthood. How these genetic alterations affect receptor function remains unknown. Here, we conducted the functional validation of distinct ADHD-related Lphn3 variants bearing mutations in the receptor's adhesion motif-containing extracellular region. We found that all variants tested disrupted the ability of Lphn3 to stabilize intercellular adhesion in a manner that was distinct between ligands classes, but which did not depend on ligand-receptor interaction parameters, thus pointing to altered intrinsic receptor signaling properties. Using G protein signaling biosensors, we determined that Lphn3 couples to Gαi1, Gαi2, Gαs, Gαq, and Gα13. However, all ADHD-related receptor variants consistently lacked intrinsic as well as ligand-dependent Gα13 coupling efficiency while maintaining unaltered coupling to Gαi, Gαs, and Gαq. Consistent with these alterations, actin remodeling functions as well as actin-relevant RhoA signaling normally displayed by the constitutively active Lphn3 receptor were impeded by select receptor variants, thus supporting additional signaling defects. Taken together, our data point to Gα13 selective signaling impairments as representing a disease-relevant pathogenicity pathway that can be inherited through Lphn3 gene polymorphisms. This study highlights the intricate interplay between Lphn3 GPCR functions and the actin cytoskeleton in modulating neurodevelopmental cues related to ADHD etiology.

The Cuban Institute of Oncology and Radiobiology experience on the beliefs and opinions about digital rectal exam in urological patients. / Creencias y opiniones sobre el examen dígito rectal en pacientes urológicos: experiencia en el Instituto de Oncología y Radiobiología (Cuba).

OBJECTIVE: To describe the beliefs, knowledge and opinions that influence the practice of digital rectal examination in a group of urological patients. METHODOLOGY: A descriptive study was conducted using convenience sampling and an anonymous questionnaire with 15 questions. The questionnaire was divided in three blocks: socio-demographic variables; delay in going to the urology clinic and taking the rectal examination; evaluation of patients’ perception of pain and discomfort during digital rectal examination and the impact of discomfort on potential future screening compliance. Percentages were used for the descriptive analysis. RESULTS: Eighty-five surveys were conducted at the Institute of Oncology and Radiobiology of Cuba. The results showed that 70.24% of participants to some extent had information about prostate cancer and 64.29% about prostate specific antigen. Only 27% thought that the digital rectal examination would be helpful, while 66.66% delayed their visit to the urologist in order to avoid the digital rectal examination and 79.76%, to elude the biopsy. It was observed that 52.39% and 36.90% of men complained of moderate and severe pain, respectively. Digital rectal examination was deemed traumatic by 61.9% of the surveyed men. A high number of patients responded they would repeat prostate exam the following year (88.09%) and 94.05% would encourage a friend to have the prostate exam. CONCLUSIONS: More than half of the sample claimed to know about prostate cancer and prostate specific antigen; however, they did not consider helpful to undergo digital rectal examination. The main reasons for not assisting to the urologist was to avoid biopsy and the digital rectal examination. Nonetheless, in most patients traumatic digital rectal examination was performed and responders said they would repeat it in the future.

OBJETIVO: Describir las creencias, los conocimientos y opiniones sobre el examen dígito rectal en un grupo de pacientes urológicos. MÉTODOS: Se desarrolló un estudio descriptivo transversal donde se evaluó un cuestionario anónimo con 15 preguntas, dividido en tres bloques: 1) variables socio-demográficas; 2) retraso en ir a la consulta de urología y su inconformidad con la práctica del examen dígito rectal; 3) percepción de dolor y malestar durante el examen dígito rectal. El cuestionario fue aplicado a una muestra de conveniencia. RESULTADOS: Se analizaron 84 encuestas aplicadas en el Instituto de Oncología y Radiobiología de Cuba. Los resultados mostraron que 70,24% de los participantes conocían en cierta medida sobre el cáncer de próstata y 64,29%, sobre el uso del antígeno prostático específico. Sólo 27% encontró útil realizarse el examen digito rectal. Los mayores impedimentos para asistir a la consulta del urólogo fueron: no someterse a una biopsia (79,76%) y evadir la práctica del examen dígito rectal (66,66%). Además, se observó que 52,39% y 36,90% de los hombres se quejaron de dolor moderado y severo respectivamente, siendo traumático el examen dígito rectal en 61,9%. Sin embargo, 88,09% de los pacientes respondió que repetirían el examen al siguiente año y el 94,05% animaría a un amigo para someterse al él. CONCLUSIONES: En la muestra de individuos estudiados, más de la mitad afirmó conocer sobre el cáncer de próstata y el antígeno prostático específico, sin embargo, no consideró provechoso someterse a un examen dígito rectal. Evitar someterse a una biopsia o al examen dígito rectal fueron los principales impedimentos para su asistencia al urólogo. A pesar de que en la mayoría de los pacientes, realizarse el examen dígito rectal fue traumático, estos consintieron en repetírselo en el futuro.