A non-image-forming visual circuit mediates the innate fear of heights in male mice.

The neural basis of fear of heights remains largely unknown. In this study, we investigated the fear response to heights in male mice and observed characteristic aversive behaviors resembling human height vertigo. We identified visual input as a critical factor in mouse reactions to heights, while peripheral vestibular input was found to be nonessential for fear of heights. Unexpectedly, we found that fear of heights in naïve mice does not rely on image-forming visual processing by the primary visual cortex. Instead, a subset of neurons in the ventral lateral geniculate nucleus (vLGN), which connects to the lateral/ventrolateral periaqueductal gray (l/vlPAG), drives the expression of fear associated with heights. Additionally, we observed that a subcortical visual pathway linking the superior colliculus to the lateral posterior thalamic nucleus inhibits the defensive response to height threats. These findings highlight a rapid fear response to height threats through a subcortical visual and defensive pathway from the vLGN to the l/vlPAG.

Molecular basis of signal transduction mediated by the human GIPR splice variants.

Glucose-dependent insulinotropic polypeptide receptor (GIPR) is a potential drug target for metabolic disorders. It works with glucagon-like peptide-1 receptor and glucagon receptor in humans to maintain glucose homeostasis. Unlike the other two receptors, GIPR has at least 13 reported splice variants (SVs), more than half of which have sequence variations at either C or N terminus. To explore their roles in endogenous peptide-mediated GIPR signaling, we determined the cryoelectron microscopy (cryo-EM) structures of the two N terminus-altered SVs (referred as GIPR-202 and GIPR-209 in the Ensembl database, SV1 and SV2 here, respectively) and investigated the outcome of coexpressing each of them in question with GIPR in HEK293T cells with respect to ligand binding, receptor expression, cAMP (adenosine 3,5-cyclic monophosphate) accumulation, ß-arrestin recruitment, and cell surface localization. It was found that while both N terminus-altered SVs of GIPR neither bound to the hormone nor elicited signal transduction per se, they suppressed ligand binding and cAMP accumulation of GIPR. Meanwhile, SV1 reduced GIPR-mediated ß-arrestin 2 responses. The cryo-EM structures of SV1 and SV2 showed that they reorganized the extracellular halves of transmembrane helices 1, 6, and 7 and extracellular loops 2 and 3 to adopt a ligand-binding pocket-occupied conformation, thereby losing binding ability to the peptide. The results suggest a form of signal bias that is constitutive and ligand-independent, thus expanding our knowledge of biased signaling beyond pharmacological manipulation (i.e., ligand specific) as well as constitutive and ligand-independent (e.g., SV1 of the growth hormone-releasing hormone receptor).

Structural insights into ligand recognition and subtype selectivity of the human melanocortin-3 and melanocortin-5 receptors.

Members of the melanocortin receptor (MCR) family that recognize different melanocortin peptides mediate a broad spectrum of cellular processes including energy homeostasis, inflammation and skin pigmentation through five MCR subtypes (MC1R-MC5R). The structural basis of subtype selectivity of the endogenous agonist γ-MSH and non-selectivity of agonist α-MSH remains elusive, as the two agonists are highly similar with a conserved HFRW motif. Here, we report three cryo-electron microscopy structures of MC3R-Gs in complex with γ-MSH and MC5R-Gs in the presence of α-MSH or a potent synthetic agonist PG-901. The structures reveal that α-MSH and γ-MSH adopt a "U-shape" conformation, penetrate into the wide-open orthosteric pocket and form massive common contacts with MCRs via the HFRW motif. The C-terminus of γ-MSH occupies an MC3R-specific complementary binding groove likely conferring subtype selectivity, whereas that of α-MSH distances itself from the receptor with neglectable contacts. PG-901 achieves the same potency as α-MSH with a shorter length by rebalancing the recognition site and mimicking the intra-peptide salt bridge in α-MSH by cyclization. Solid density confirmed the calcium ion binding in MC3R and MC5R, and the distinct modulation effects of divalent ions were demonstrated. Our results provide insights into ligand recognition and subtype selectivity among MCRs, and expand the knowledge of signal transduction among MCR family members.

The Role of Hypoxia-inducible Factor-1 in Bladder Cancer.

Bladder cancer (BC) is one of the most common malignant tumors worldwide and poses a significant hazard to human health. During the development of BC, hypoxia plays a crucial role. Hypoxia-inducible factor (HIF) is a key transcription factor for hypoxic adaptation, which regulates the transcription of various genes, including inflammation, angiogenesis, and glycolytic metabolism. Recent studies have shown the precise role of HIF in various biological behaviors of BC. More importantly, a new antitumor medication targeting HIF-2 has been used to treat renal cancer. However, therapies targeting HIF-1 in BC have not yet been developed. In this review, we discussed how HIF-1 is expressed and affects the growth, metastasis, and angiogenesis of BC. At the same time, we investigated several HIF-1 inhibitors that provide new perspectives for targeting HIF-1.

Florid cystitis glandularis (intestinal type) with mucus extravasation: Two case reports and literature review.

Background: Cystitis glandularis is a common bladder epithelial lesion characterized by hyperplasia and metaplasia of the bladder mucosa epithelium. The pathogenesis of cystitis glandularis of the intestinal type is unknown and less common. When cystitis glandularis (intestinal type) is extremely severely differentiated, it is called florid cystitis glandularis (the occurrence is extremely rare). Case summary: Both patients were middle-aged men. In patient 1, the lesion was also seen in the posterior wall and was diagnosed more than 1 year ago as cystitis glandularis with urethral stricture. Patient 2 was examined for symptoms such as hematuria and was found to have an occupied bladder; both were treated surgically, and the postoperative pathology was diagnosed as florid cystitis glandularis (intestinal type), with mucus extravasation. Conclusion: The pathogenesis of cystitis glandularis (intestinal type) is unknown and less common. When cystitis glandularis of the intestinal type is extremely severely differentiated, we call it florid cystitis glandularis. It is more common in the bladder neck and trigone. The clinical manifestations are mainly symptoms of bladder irritation, or hematuria as the main complaint, which rarely leads to hydronephrosis. Imaging is nonspecific and the diagnosis depends on pathology. Surgical excision of the lesion is possible. Due to the malignant potential of cystitis glandularis of intestinal type, postoperative follow-up is required.

Case Report: Adrenal glands degenerated schwannoma: Report of three cases and literature review.

Background: Schwannoma is a benign tumor, of which degenerated schwannoma is a subtype. Retroperitoneal schwannomas are extremely rare, as they account for only 3% of retroperitoneal tumors.Degenerated schwannoma is a schwannoma subtype. However,degenerated schwannoma occurring in the adrenal glands is extremely rare. Case summary: Case 1: A 42-year-old man was referred to our hospital for further examination of a left adrenal mass that was incidentally discovered during a routine physical check-up.No significant abnormalities were found in laboratory tests results. Robotic-assisted laparoscopic excision of the left adrenal gland was performed under general anesthesia. Case 2: A 47-year-old man was admitted to the hospital because of a left adrenal mass found on a routine physical examination.The patient was previously in good health, and there was no family history of a similar disorder. Left-sided laparoscopic adrenalectomy was performed under general anaesthesia. Case 3: A 62-year-old woman with hypertension and diabetes mellitus was referred to our hospital after an incidentally found left adrenal mass.There was no family history of a similar disorder. Left-sided laparoscopic adrenalectomy was performed under general anaesthesia. None of the patients had a recurrence in our study during the postoperative follow-up. Conclusion: Degenerated schwannoma of the adrenal glands is very rare. The clinical presentations of degenerated schwannoma are nonspecific; a small number of patients do not have any symptoms, and the mass is only found incidentally during physical examination for any number of reasons. The preoperative diagnosis of adrenal degenerated schwannoma is difficult because the diagnosis must rely on pathological examination and immunohistochemistry assays. The management is surgical excision and regular follow-up.

Structural basis of signaling regulation of the human melanocortin-2 receptor by MRAP1.

G protein-coupled receptors (GPCRs) are regulated by various downstream proteins, of which the melanocortin receptor accessory protein 1 (MRAP1) is closely involved in the regulation of melanocortin receptor 2 (MC2R). Assisted by MRAP1, MC2R responds to adrenocorticotropic hormone (ACTH) and stimulates glucocorticoid biogenesis and cortisol secretion. MC2R activation plays an essential role in the hypothalamic-pituitary-adrenal (HPA) axis that regulates stress response, while its dysfunction causes glucocorticoid insufficiency- or cortisol excess-associated disorders. Here, we present a cryo-electron microscopy (cryo-EM) structure of the ACTH-bound MC2R-Gs-MRAP1 complex. Our structure, together with mutagenesis analysis, reveals a unique sharp kink at the extracellular region of MRAP1 and the 'seat-belt' effect of MRAP1 on stabilizing ACTH binding and MC2R activation. Mechanisms of ACTH recognition by MC2R and receptor activation are also demonstrated. These findings deepen our understanding of GPCR regulation by accessory proteins and provide valuable insights into the ab initio design of therapeutic agents targeting MC2R.

A high-throughput screening campaign against PFKFB3 identified potential inhibitors with novel scaffolds.

The growth of solid tumors depends on tumor vascularization and the endothelial cells (ECs) that line the lumen of blood vessels. ECs generate a large fraction of ATP through glycolysis, and elevation of their glycolytic activity is associated with angiogenic behavior in solid tumors. 6-Phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3) positively regulates glycolysis via fructose-2/6-bisphosphate, the product of its kinase activity. Partial inhibition of glycolysis in tumor ECs by targeting PFKFB3 normalizes the otherwise abnormal tumor vessels, thereby reducing metastasis and improving the outcome of chemotherapy. Although a limited number of tool compounds exist, orally available PFKFB3 inhibitors are unavailable. In this study we conducted a high-throughput screening campaign against the kinase activity of PFKFB3, involving 250,240 chemical compounds. A total of 507 initial hits showing >50% inhibition at 20 µM were identified, 66 of them plus 1 analog from a similarity search consistently displayed low IC50 values (<10 µM). In vitro experiments yielded 22 nontoxic hits that suppressed the tube formation of primary human umbilical vein ECs at 10 µM. Of them, 15 exhibited binding affinity to PFKFB3 in surface plasmon resonance assays, including 3 (WNN0403-E003, WNN1352-H007 and WNN1542-F004) that passed the pan-assay interference compounds screening without warning flags. This study provides potential leads to the development of new PFKFB3 inhibitors.

Case report: High-grade endometrial stromal sarcoma with adrenal glands metastases: An unreported site of metastasis.

Background: Endometrial stromal sarcoma is a relatively rare malignant tumor that derives from the malignant transformation of primitive uterine mesenchymal cells. It can lead to distant metastases. High-grade endometrial stromal sarcoma is extremely rare. The adrenal glands are an unreported site of metastasis. Case summary: A 71-year-old woman with a diagnosis of endometrial stromal sarcoma 30 months ago. After receiving treatment with radiotherapy and chemotherapy, the patient was kept asymptomatic during the follow-up until 2 years later, when she complained of dyspnea. Pulmonary and right adrenal gland metastases were detected by 18F-FDG PET/CT. The right upper lobe mass was diagnosed as a high-grade endometrial stromal sarcoma metastasis after postoperative pathology. Due to the patient's high risk of surgery, as she had many underlying diseases, we performed adequate preoperative preparation. The physical examination revealed that a hard mass was palpable in the right renal area. The right adrenal mass was resected in our hospital. Immunohistochemistry showed ER (-), PR (-), CD10 (+), P16 (+), Ki-67 (50%). The final diagnosis on pathological examination was a high-grade ESS metastatic to the right adrenal gland. The patient continued treatment in other hospitals after surgical resection. After four months of postoperative follow-up, metastasis was detected again during a PET/CT examination at an outside hospital. Conclusion: Endometrial stromal sarcoma is rare, and the adrenal glands are an unreported site of metastasis. It has no specific clinical symptoms and mainly found for other reasons. The diagnosis still depends on pathology and immunohistochemistry. If there is no relevant past history, it is difficult to exclude a primary adrenal tumor.

Case Report: The ectopic pancreas in the adrenal glands: It was found due to elevated blood pressure and initially diagnosed as adrenal adenoma.

Background: The ectopic pancreas is a kind of congenital malformation formed during embryonic development, which has no anatomical relationship with the normal pancreas and is a rare solid disease. The ectopic pancreas in the adrenal glands is extremely rare. Case summary: A 32-year-old man was admitted to the hospital after experiencing elevated blood pressure for 2 years as well as dizziness and blurred vision for 2 weeks. He had an elevated blood pressure of 170/110 mmHg (1 mmHg = 0.133 kPa) on physical examination 2 years ago, without palpitations, chest pain, and chest tightness. Two weeks ago, he presented with dizziness and blurred vision. Blood renin and aldosterone levels were elevated. Plain CT and contrast-enhanced CT scan showed nodular thickening of the left adrenal and homogeneous enhancement, which was initially considered adrenal adenoma. The postoperative pathology supported the ectopic pancreas in the left adrenal. After 78 months of postoperative follow-up, no recurrence was observed, but his blood pressure remained persistently high. Conclusion: The ectopic pancreas occurring in the adrenal glands is extremely rare, has no specific clinical symptoms, and is mainly found for other reasons. It can easily be misdiagnosed as an adrenal adenoma. The final confirmation of the diagnosis still depends on the pathological biopsy. A great deal of reporting is still required for whether there is a correlation with elevated blood pressure.

Molecular Hydrogen Reduces Electromagnetic Pulse-Induced Male Rat Reproductive System Damage in a Rodent Model.

Infertility has got to be a broadly concerned social issue these days, in which the malefactor cannot be overlooked. Numerous studies have shown that electromagnetic pulse (EMP) radiation may have seriously damaging effects on reproductive health, through nonthermal effects and oxidative stress. Molecular hydrogen, a selective hydroxyl radical scavenger, explains the protective effects against many diseases closely associated with oxidative damage, such as ionizing radiation (IR). We sought to characterize the beneficial effects of molecular hydrogen on the male reproductive system in a rodent EMP exposure model. The 8-week-old male Sprague-Dawley rats were exposed to EMP (peak intensity 1000 kV/m, pulse edge 20 ns, pulse width 200 ns, 1 Hz, and 200 pulses), with or without hydrogen-rich water. The pathological structure of the testis, the rate of apoptosis of the testis, the serum testosterone level, the sperm parameters, and the activity of the antioxidant enzymes of the testis were measured. Then, transcriptomic and untargeted metabolomic analyses were applied to uncover the underlying mechanism. Exposure to EMP increased testicular apoptosis rate and apoptosis protein level, decreased sperm viability and motility, decreased serum testosterone levels, and diminished testicular antioxidant capacity. Molecular hydrogen-alleviated damage decreased the testicular apoptosis rate and apoptosis protein level, increased sperm motility, increased serum testosterone levels, and improved antioxidative capacity. Omics results showed that molecular hydrogen has a strong influence on metabolic pathways, and EMP affects mainly oxidative phosphorylation, TNF signaling pathways, and cytokine-receptor interactions. The mechanism of molecular hydrogen's effect may be related to the reversal of some metabolite levels. These observations warrant molecular hydrogen as an innovative approach for potential protection against EMP.

Structural insights into ligand recognition and selectivity of somatostatin receptors.

Somatostatin receptors (SSTRs) play versatile roles in inhibiting the secretion of multiple hormones such as growth hormone and thyroid-stimulating hormone, and thus are considered as targets for treating multiple tumors. Despite great progress made in therapeutic development against this diverse receptor family, drugs that target SSTRs still show limited efficacy with preferential binding affinity and conspicuous side-effects. Here, we report five structures of SSTR2 and SSTR4 in different states, including two crystal structures of SSTR2 in complex with a selective peptide antagonist and a non-peptide agonist, respectively, a cryo-electron microscopy (cryo-EM) structure of Gi1-bound SSTR2 in the presence of the endogenous ligand SST-14, as well as two cryo-EM structures of Gi1-bound SSTR4 in complex with SST-14 and a small-molecule agonist J-2156, respectively. By comparison of the SSTR structures in different states, molecular mechanisms of agonism and antagonism were illustrated. Together with computational and functional analyses, the key determinants responsible for ligand recognition and selectivity of different SSTR subtypes and multiform binding modes of peptide and non-peptide ligands were identified. Insights gained in this study will help uncover ligand selectivity of various SSTRs and accelerate the development of new molecules with better efficacy by targeting SSTRs.

A distinctive ligand recognition mechanism by the human vasoactive intestinal polypeptide receptor 2.

Class B1 of G protein-coupled receptors (GPCRs) comprises 15 members activated by physiologically important peptide hormones. Among them, vasoactive intestinal polypeptide receptor 2 (VIP2R) is expressed in the central and peripheral nervous systems and involved in a number of pathophysiological conditions, including pulmonary arterial hypertension, autoimmune and psychiatric disorders, in which it is thus a valuable drug target. Here, we report the cryo-electron microscopy structure of the human VIP2R bound to its endogenous ligand PACAP27 and the stimulatory G protein. Different from all reported peptide-bound class B1 GPCR structures, the N-terminal α-helix of VIP2R adopts a unique conformation that deeply inserts into a cleft between PACAP27 and the extracellular loop 1, thereby stabilizing the peptide-receptor interface. Its truncation or extension significantly decreased VIP2R-mediated cAMP accumulation. Our results provide additional information on peptide recognition and receptor activation among class B1 GPCRs and may facilitate the design of better therapeutics.

Structural insights into multiplexed pharmacological actions of tirzepatide and peptide 20 at the GIP, GLP-1 or glucagon receptors.

Glucose homeostasis, regulated by glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-1 (GLP-1) and glucagon (GCG) is critical to human health. Several multi-targeting agonists at GIPR, GLP-1R or GCGR, developed to maximize metabolic benefits with reduced side-effects, are in clinical trials to treat type 2 diabetes and obesity. To elucidate the molecular mechanisms by which tirzepatide, a GIPR/GLP-1R dual agonist, and peptide 20, a GIPR/GLP-1R/GCGR triagonist, manifest their multiplexed pharmacological actions over monoagonists such as semaglutide, we determine cryo-electron microscopy structures of tirzepatide-bound GIPR and GLP-1R as well as peptide 20-bound GIPR, GLP-1R and GCGR. The structures reveal both common and unique features for the dual and triple agonism by illustrating key interactions of clinical relevance at the near-atomic level. Retention of glucagon function is required to achieve such an advantage over GLP-1 monotherapy. Our findings provide valuable insights into the structural basis of functional versatility of tirzepatide and peptide 20.

Structural perspective of class B1 GPCR signaling.

Class B1 G protein-coupled receptors (GPCRs) play important roles in human physiology and disease pathology. Using cryo-electron microscopy (cryo-EM) and X-ray crystallography, the 3D structures of all 15 members of this receptor subfamily have been determined in recent years at the near-atomic level. Although they share many structural commonalities, they show distinct features in terms of ligand recognition and receptor activation. In-depth structural analyses have yielded valuable insights into the N termini of both peptide hormones and cognate receptors, the outward movement of transmembrane helix 6 (TM6), the allosteric modulation sites located in the transmembrane domain (TMD), and the constitutive signaling bias mediated by receptor splice variants. These provide new directions for the design of better therapeutic agents, thereby making these targets more druggable.

GLP-1 mimetics as a potential therapy for nonalcoholic steatohepatitis.

Nonalcoholic steatohepatitis (NASH), as a severe form of nonalcoholic fatty liver disease (NAFLD), is characterized by liver steatosis, inflammation, hepatocellular injury and different degrees of fibrosis. The pathogenesis of NASH is complex and multifactorial, obesity and type 2 diabetes mellitus (T2DM) have been implicated as major risk factors. Glucagon-like peptide-1 receptor (GLP-1R) is one of the most successful drug targets of T2DM and obesity, and its peptidic ligands have been proposed as potential therapeutic agents for NASH. In this article we provide an overview of the pathophysiology and management of NASH, with a special focus on the pharmacological effects and possible mechanisms of GLP-1 mimetics in treating NAFLD/NASH, including dual and triple agonists at GLP-1R, glucose-dependent insulinotropic polypeptide receptor or glucagon receptor.

Actuation delay compensation of robots in semi-physical test.

In general, the traditional spacecraft semi-physical docking tests include the evaluation of docking and separation performance. However, these tests often rely on "specific" equipment, such as specially designed actuators and fast-response hydraulic systems, to meet the stringent dynamic response requirements of semi-physical testing. In this paper, a novel docking test platform is designed based on a general-purpose industrial manipulator using 3-D force and 3-D torque sensors. Different from the traditional solution, this novel platform is well-assembled and cost-effective. Furthermore, an actuation delay compensation method is introduced to improve the performance. Finally, the proposed method is evaluated using simulations. The results show that the novel method is with promising performance in terms of actuation delay compensation.

Structures of the human cholecystokinin receptors bound to agonists and antagonists.

Cholecystokinin receptors, CCKAR and CCKBR, are important neurointestinal peptide hormone receptors and play a vital role in food intake and appetite regulation. Here, we report three crystal structures of the human CCKAR in complex with different ligands, including one peptide agonist and two small-molecule antagonists, as well as two cryo-electron microscopy structures of CCKBR-gastrin in complex with Gi2 and Gq, respectively. These structures reveal the recognition pattern of different ligand types and the molecular basis of peptide selectivity in the cholecystokinin receptor family. By comparing receptor structures in different conformational states, a stepwise activation process of cholecystokinin receptors is proposed. Combined with pharmacological data, our results provide atomic details for differential ligand recognition and receptor activation mechanisms. These insights will facilitate the discovery of potential therapeutics targeting cholecystokinin receptors.

Structural insights into ligand recognition and activation of the melanocortin-4 receptor.

Melanocortin-4 receptor (MC4R) plays a central role in the regulation of energy homeostasis. Its high sequence similarity to other MC receptor family members, low agonist selectivity and the lack of structural information concerning MC4R-specific activation have hampered the development of MC4R-seletive therapeutics to treat obesity. Here, we report four high-resolution structures of full-length MC4R in complex with the heterotrimeric Gs protein stimulated by the endogenous peptide ligand α-MSH, FDA-approved drugs afamelanotide (Scenesse™) and bremelanotide (Vyleesi™), and a selective small-molecule ligand THIQ, respectively. Together with pharmacological studies, our results reveal the conserved binding mode of peptidic agonists, the distinctive molecular details of small-molecule agonist recognition underlying receptor subtype selectivity, and a distinct activation mechanism for MC4R, thereby offering new insights into G protein coupling. Our work may facilitate the discovery of selective therapeutic agents targeting MC4R.