Conformational transitions and activation of the adhesion receptor CD97.

Adhesion G protein-coupled receptors (aGPCRs) are evolutionarily ancient receptors involved in a variety of physiological and pathophysiological processes. Modulators of aGPCR, particularly antagonists, hold therapeutic promise for diseases like cancer and immune and neurological disorders. Hindered by the inactive state structural information, our understanding of antagonist development and aGPCR activation faces challenges. Here, we report the cryo-electron microscopy structures of human CD97, a prototypical aGPCR that plays crucial roles in immune system, in its inactive apo and G13-bound fully active states. Compared with other family GPCRs, CD97 adopts a compact inactive conformation with a constrained ligand pocket. Activation induces significant conformational changes for both extracellular and intracellular sides, creating larger cavities for Stachel sequence binding and G13 engagement. Integrated with functional and metadynamics analyses, our study provides significant mechanistic insights into the activation and signaling of aGPCRs, paving the way for future drug discovery efforts.

Structural basis for the tethered peptide activation of adhesion GPCRs.

Adhesion G-protein-coupled receptors (aGPCRs) are important for organogenesis, neurodevelopment, reproduction and other processes1-6. Many aGPCRs are activated by a conserved internal (tethered) agonist sequence known as the Stachel sequence7-12. Here, we report the cryogenic electron microscopy (cryo-EM) structures of two aGPCRs in complex with Gs: GPR133 and GPR114. The structures indicate that the Stachel sequences of both receptors assume an α-helical-bulge-ß-sheet structure and insert into a binding site formed by the transmembrane domain (TMD). A hydrophobic interaction motif (HIM) within the Stachel sequence mediates most of the intramolecular interactions with the TMD. Combined with the cryo-EM structures, biochemical characterization of the HIM motif provides insight into the cross-reactivity and selectivity of the Stachel sequences. Two interconnected mechanisms, the sensing of Stachel sequences by the conserved 'toggle switch' W6.53 and the constitution of a hydrogen-bond network formed by Q7.49/Y7.49 and the P6.47/V6.47φφG6.50 motif (φ indicates a hydrophobic residue), are important in Stachel sequence-mediated receptor activation and Gs coupling. Notably, this network stabilizes kink formation in TM helices 6 and 7 (TM6 and TM7, respectively). A common Gs-binding interface is observed between the two aGPCRs, and GPR114 has an extended TM7 that forms unique interactions with Gs. Our structures reveal the detailed mechanisms of aGPCR activation by Stachel sequences and their Gs coupling.

Structures of the glucocorticoid-bound adhesion receptor GPR97-Go complex.

Adhesion G-protein-coupled receptors (GPCRs) are a major family of GPCRs, but limited knowledge of their ligand regulation or structure is available1-3. Here we report that glucocorticoid stress hormones activate adhesion G-protein-coupled receptor G3 (ADGRG3; also known as GPR97)4-6, a prototypical adhesion GPCR. The cryo-electron microscopy structures of GPR97-Go complexes bound to the anti-inflammatory drug beclomethasone or the steroid hormone cortisol revealed that glucocorticoids bind to a pocket within the transmembrane domain. The steroidal core of glucocorticoids is packed against the 'toggle switch' residue W6.53, which senses the binding of a ligand and induces activation of the receptor. Active GPR97 uses a quaternary core and HLY motif to fasten the seven-transmembrane bundle and to mediate G protein coupling. The cytoplasmic side of GPR97 has an open cavity, where all three intracellular loops interact with the Go protein, contributing to the high basal activity of GRP97. Palmitoylation at the cytosolic tail of the Go protein was found to be essential for efficient engagement with GPR97 but is not observed in other solved GPCR complex structures. Our work provides a structural basis for ligand binding to the seven-transmembrane domain of an adhesion GPCR and subsequent G protein coupling.

Structures of the ADGRG2-Gs complex in apo and ligand-bound forms.

Adhesion G protein-coupled receptors are elusive in terms of their structural information and ligands. Here, we solved the cryogenic-electron microscopy (cryo-EM) structure of apo-ADGRG2, an essential membrane receptor for maintaining male fertility, in complex with a Gs trimer. Whereas the formations of two kinks were determinants of the active state, identification of a potential ligand-binding pocket in ADGRG2 facilitated the screening and identification of dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate and deoxycorticosterone as potential ligands of ADGRG2. The cryo-EM structures of DHEA-ADGRG2-Gs provided interaction details for DHEA within the seven transmembrane domains of ADGRG2. Collectively, our data provide a structural basis for the activation and signaling of ADGRG2, as well as characterization of steroid hormones as ADGRG2 ligands, which might be used as useful tools for further functional studies of the orphan ADGRG2.

Nidogen-2 is a Novel Endogenous Ligand of LGR4 to Inhibit Vascular Calcification.

BACKGROUND: Vascular calcification is closely related to the all-cause mortality of cardiovascular events. Basement membrane protein nidogen-2 is a key component of the vascular extracellular matrix microenvironment and we recently found it is pivotal for the maintenance of contractile phenotype in vascular smooth muscle cells (VSMCs). However, whether nidogen-2 is involved in VSMCs osteochondrogenic transition and vascular calcification remains unclear. METHODS: VSMCs was treated with high-phosphate to study VSMC calcification in vitro. Three different mice models (5/6 nephrectomy-induced chronic renal failure, cholecalciferol-overload, and periadventitially administered with CaCl2) were used to study vascular calcification in vivo. Membrane protein interactome, coimmunoprecipitation, flow cytometric binding assay, surface plasmon resonance, G protein signaling, VSMCs calcium assays were performed to clarify the phenotype and elucidate the molecular mechanisms. RESULTS: Nidogen-2 protein levels were significantly reduced in calcified VSMCs and aortas from mice in different vascular calcification model. Nidogen-2 deficiency exacerbated high-phosphate-induced VSMC calcification, whereas the addition of purified nidogen-2 protein markedly alleviated VSMC calcification in vitro. Nidogen-2-/- mice exhibited aggravated aorta calcification compared to wild-type (WT) mice in response to 5/6 nephrectomy, cholecalciferol-overload, and CaCl2 administration. Further unbiased coimmunoprecipitation and interactome analysis of purified nidogen-2 and membrane protein in VSMCs revealed that nidogen-2 directly binds to LGR4 (leucine-rich repeat G-protein-coupled receptor 4) with KD value 26.77 nM. LGR4 deficiency in VSMCs in vitro or in vivo abolished the protective effect of nidogen-2 on vascular calcification. Of interest, nidogen-2 biased activated LGR4-Gαq-PKCα (protein kinase Cα)-AMPKα1 (AMP-activated protein kinase α1) signaling to counteract VSMCs osteogenic transition and mineralization. CONCLUSIONS: Nidogen-2 is a novel endogenous ligand of LGR4 that biased activated Gαq- PKCα-AMPKα1 signaling and inhibited vascular calcification.

Theory-based interventions aimed at promoting physical activity in pregnant women: A systematic review and meta-analysis of randomized controlled trials.

OBJECTIVES: The objectives were to assess (i) the quality of theory implementation, (ii) the application of behavior change techniques, and (iii) the effectiveness of theory-based interventions in promoting physical activity in pregnant women and improving maternal and neonatal outcomes. METHODS: A systematic search was conducted across 8 databases (Cumulative Index to Nursing and Allied Health Literature, the Cochrane Library, EMBASE, MEDLINE, APA PsycINFO, PubMed, SPORTDiscus, and Web of Science) to identify randomized controlled trials published from database inception to 8 July 2023. The Cochrane risk-of-bias 2.0 tool was used to evaluate the quality of the included studies. The theory coding scheme was used to measure the quality of theory implementation, and behavior change techniques were coded according to behavior change taxonomy (version 1). The meta-analysis was performed using RevMan 5.3. The Grading of Recommendations, Assessment, Development, and Evaluation Approach was used to assess the certainty of evidence. RESULTS: Eleven studies met the study criteria. Nine studies were based on one theory, while two studies were based on a combination of two theories. The quality of theory implementation was generally moderate. A total of 24 unique behavior change techniques were extracted. The most commonly used types of behavior change techniques were 'instruction on how to perform the behavior' (n = 9), 'goal setting' (behavior) (n = 8), 'action planning' (n = 7), and 'information about health consequences' (n = 7). Theory-based interventions significantly improved moderate-to-vigorous physical activity (standardized mean difference (SMD) = 0.17, 95 % confidence interval (CI) [0.04, 0.30], P = 0.01; moderate certainty of evidence), reduced the average gestational weight gain per week (mean difference (MD) = -0.06, 95 % CI [-0.11, -0.01], P = 0.02; moderate certainty of evidence), and decreased the incidence of gestational diabetes mellitus (risk ratio (RR) = 0.64, 95 % CI [0.46, 0.89], P = 0.008; high certainty of evidence). However, the effects of theory-based interventions on total physical activity, total gestational weight gain and the incidence of gestational hypertension and preterm delivery were unclear (P > 0.05). CONCLUSIONS: (i) Most of the studies exhibited a moderate level of theory implementation quality. (ii) The use of theories varies, but common behavior change techniques were found across studies. (iii) Theory-based interventions can improve physical activity and maternal and neonatal outcomes and appear to be safe. Appropriate health behavior theories and behavior change techniques should be fully utilized in future interventions. REGISTRATION: PROSPERO: CRD42023440886. TWEETABLE ABSTRACT: Theory-based interventions can improve physical activity and maternal and neonatal outcomes and appear to be safe. Appropriate health behavior theories and behavior change techniques should be fully utilized in the development of future interventions.

Physical activity levels and influencing factors among pregnant women in China: A systematic review and meta-analysis.

BACKGROUND: Physical activity during pregnancy has been recommended as an effective measure to prevent various pregnancy complications. However, global physical activity participation during pregnancy is not optimal, and the factors influencing physical activity participation during pregnancy need to be further investigated. In China, where there are no localized guidelines for physical activity during pregnancy, the prevalence of meeting recommended physical activity levels among Chinese pregnant women is still unclear. OBJECTIVES: This study aimed to comprehensively review the prevalence of meeting recommended physical activity levels among pregnant women in China and to further explore the factors influencing physical activity participation during pregnancy. DESIGN: This was a systematic review and meta-analysis. METHODS: A systematic review was conducted in both English and Chinese databases from inception until August 1, 2023. Two reviewers independently screened literature, assessed study eligibility and extracted data. The Agency for Healthcare Research and Quality was used to evaluate methodological quality of included studies. The pooled prevalence was calculated using a random-effects model. Subgroup analyses were conducted to explore sources of heterogeneity. RESULTS: A total of 12 cross-sectional studies, including 11,323 Chinese pregnant women with a mean age ranging from 27.0 to 33.0 years, met the inclusion criteria. The prevalence of meeting recommended physical activity levels among pregnant women in China was 21.0 % (95 % confidence interval (CI):12.5 %-29.5 %). A higher prevalence of meeting recommended physical activity levels was observed among pregnant women who were in their second trimester, who were living in the southern region, who were assessed by validated questionnaires, and who used 150 min physical activity per week as a criterion for meeting recommendation. CONCLUSIONS: The findings suggested a low prevalence of meeting recommended physical activity levels among Chinese pregnant women, which was affected by a variety of factors. It is recommended that further research be conducted in the future to explore physical activity intervention strategies for women of childbearing age before and during pregnancy based on the factors affecting physical activity to improve physical activity compliance, maternal and child health and population quality. REGISTRATION NUMBER: CRD42022372722 (PROSPERO).

Effectiveness of web-based interventions for women with urinary incontinence: protocol for a systematic review and meta-analysis of randomised controlled trials.

INTRODUCTION: Urinary incontinence (UI) is one of the most common chronic diseases among women, which can endanger their physical and mental health and incur a heavy financial burden on both individuals and society. Web-based interventions (WBIs) have been applied to manage women's UI, but their effectiveness has remained inconclusive. This systematic review and meta-analysis aims to explore the effectiveness of WBIs on self-reported symptom severity, condition-specific quality of life, adherence to pelvic floor muscle training (primary outcomes) and other extensive secondary outcomes among women with UI. We also aimed to investigate whether intervention characteristics (format, interactivity and main technology) have impacts on the effectiveness of primary outcomes. METHODS AND ANALYSIS: This systematic review protocol was developed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols guidelines. 10 electronic databases will be comprehensively searched from their inception to 1 May 2024, along with grey literature searches and manual reviews of relevant reference lists to identify eligible randomised controlled trials. The methodological quality of the included studies will be assessed by two reviewers based on the Cochrane Risk of Bias Tool. Meta-analyses will be conducted via Stata V.12.0. Leave-one-out sensitivity analyses will be performed, and publication bias will be evaluated using funnel plots and Egger's test. Subgroup analyses regarding intervention format, interactivity and main technology will be carried out. ETHICS AND DISSEMINATION: No ethics approval is needed for this review since no primary data are to be collected. The results of this review will help develop an optimal WBI for women with UI, thereby providing them with maximum benefits. The findings will be disseminated via a peer-reviewed journal or conference presentation. PROSPERO REGISTRATION NUMBER: CRD42023435047.

Prevalence of Chinese pregnant women meeting physical activity recommendation and its influencing factors: a protocol for systematic review and meta-analysis.

INTRODUCTION: Regular physical activity during pregnancy is effective in preventing diseases and promoting the health outcomes of mothers and babies. However, the level of physical activity among them is not ideal. Especially in China, the proportion of pregnant women who meet the recommendation of physical activity in the guidelines is even lower. Thus, we aim to evaluate the prevalence of meeting physical activity recommendation and its influencing factors during pregnancy in China. METHODS AND ANALYSIS: This protocol is developed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols guidelines. PubMed, Web of Science, Scopus, CINAHL, MEDLINE, PsycINFO, EMBASE, China National Knowledge Infrastructure (CNKI), China Science and Technology Journal Database (Weipu) and WanFang Data will be comprehensively searched by two reviewers. Studies that report the prevalence of Chinese pregnant women meeting physical activity recommendation will be included. Two reviewers will independently assess eligibility, extract data and evaluate methodological quality. Data including authors, publication years, language, geographical region, tools, trimesters, prevalence and influence factors will be extracted. Data will be analysed by Stata V.11 statistical software. ETHICS AND DISSEMINATION: No formal ethics approval is required for this protocol and no primary data are to be collected. Findings from this review may be useful to develop interventions for the physical activity of pregnant women in China. The results will be disseminated through peer-reviewed journals, conference presentations and public events. PROSPERO REGISTRATION NUMBER: CRD42022372722.

Psychometric properties of the Chinese version of the fathers' fear of childbirth scale: A cross-sectional study.

Background and Aim: Fear of childbirth (FOC) is one of the most common mental health concerns among expectant fathers, which can cause adverse consequences for themselves and their families. A valid and accurate tool is the key to the identification of FOC. This study aimed to translate and culturally adapt the fathers' fear of childbirth scale (FFCS) into simplified Chinese and test the scale's psychometric properties among expectant fathers in mainland China. Methods: Researchers obtained translation permission and followed the multiphase translation guidelines to develop the Chinese version of the fathers' fear of childbirth scale (C-FFCS). Relevant psychometric properties were selected for the scale's psychometric validation on the basis of the Consensus-based Standards for the Selection of Health Status Measurement Instruments checklist. In this cross-sectional study, two samples of expectant fathers were collected in a university-affiliated hospital in Hangzhou between September and October 2022. Results: A total of 381 expectant fathers completed the C-FFCS, resulting in an effective response rate of 95.6%. The C-FFCS is a 3-factor structure consisting of 16 items, which explained 66.374% of the total variance. The content validity index of items ranged from 0.833 to 1.00, and the scale-level content validity index was 0.931. The confirmatory factor analysis confirmed the scale's 3-factor structure. Evidence of convergent validity (average variance extracted = 0.508-0.780) as well as discriminant validity offered excellent psychometric support. The Cronbach's α coefficient, McDonald's ω coefficient, intraclass correlation coefficient, Spearman-Brown coefficient, and Guttman split-half coefficient are within the satisfactory range (> 0.80). Significant correlations between the scores of the C-FFCS and Childbirth Attitude Questionnaire (r = 0.658, p < 0.01) and Fear of Birth Scale (r = 0.555, p < 0.01) both revealed good concurrent validity. The structure of C-FFCS was invariant across different parity groups, with no floor and ceiling effect. Conclusion: The C-FFCS was demonstrated to be a sound instrument with good reliability and validity for measuring Chinese expectant fathers' FOC levels. However, further studies are advocated to verify the C-FFCS among a larger sample that is more representative of the Chinese expectant father population.

Structural studies of phosphorylation-dependent interactions between the V2R receptor and arrestin-2.

Arrestins recognize different receptor phosphorylation patterns and convert this information to selective arrestin functions to expand the functional diversity of the G protein-coupled receptor (GPCR) superfamilies. However, the principles governing arrestin-phospho-receptor interactions, as well as the contribution of each single phospho-interaction to selective arrestin structural and functional states, are undefined. Here, we determined the crystal structures of arrestin2 in complex with four different phosphopeptides derived from the vasopressin receptor-2 (V2R) C-tail. A comparison of these four crystal structures with previously solved Arrestin2 structures demonstrated that a single phospho-interaction change results in measurable conformational changes at remote sites in the complex. This conformational bias introduced by specific phosphorylation patterns was further inspected by FRET and 1H NMR spectrum analysis facilitated via genetic code expansion. Moreover, an interdependent phospho-binding mechanism of phospho-receptor-arrestin interactions between different phospho-interaction sites was unexpectedly revealed. Taken together, our results provide evidence showing that phospho-interaction changes at different arrestin sites can elicit changes in affinity and structural states at remote sites, which correlate with selective arrestin functions.

Ligand recognition, unconventional activation, and G protein coupling of the prostaglandin E2 receptor EP2 subtype.

Selective modulation of the heterotrimeric G protein α S subunit-coupled prostaglandin E2 (PGE2) receptor EP2 subtype is a promising therapeutic strategy for osteoporosis, ocular hypertension, neurodegenerative diseases, and cardiovascular disorders. Here, we report the cryo-electron microscopy structure of the EP2-Gs complex with its endogenous agonist PGE2 and two synthesized agonists, taprenepag and evatanepag (CP-533536). These structures revealed distinct features of EP2 within the EP receptor family in terms of its unconventional receptor activation and G protein coupling mechanisms, including activation in the absence of a typical W6.48 "toggle switch" and coupling to Gs via helix 8. Moreover, inspection of the agonist-bound EP2 structures uncovered key motifs governing ligand selectivity. Our study provides important knowledge for agonist recognition and activation mechanisms of EP2 and will facilitate the rational design of drugs targeting the PGE2 signaling system.