Structural insights into somatostatin receptor 5 bound with cyclic peptides.

Somatostatin receptor 5 (SSTR5) is highly expressed in ACTH-secreting pituitary adenomas and is an important drug target for the treatment of Cushing's disease. Two cyclic SST analog peptides (pasireotide and octreotide) both can activate SSTR5 and SSTR2. Pasireotide is preferential binding to SSTR5 than octreotide, while octreotide is biased to SSTR2 than SSTR5. The lack of selectivity of both pasireotide and octreotide causes side effects, such as hyperglycemia, gastrointestinal disturbance, and abnormal glucose homeostasis. However, little is known about the binding and selectivity mechanisms of pasireotide and octreotide with SSTR5, limiting the development of subtype-selective SST analog drugs specifically targeting SSTR5. Here, we report two cryo-electron microscopy (cryo-EM) structures of SSTR5-Gi complexes activated by pasireotide and octreoitde at resolutions of 3.09 Å and 3.24 Å, respectively. In combination with structural analysis and functional experiments, our results reveal the molecular mechanisms of ligand recognition and receptor activation. We also demonstrate that pasireotide preferentially binds to SSTR5 through the interactions between Tyr(Bzl)/DTrp of pasireotide and SSTR5. Moreover, we find that the Q2.63, N6.55, F7.35 and ECL2 of SSTR2 play a crucial role in octreotide biased binding of SSTR2. Our results will provide structural insights and offer new opportunities for the drug discovery of better selective pharmaceuticals targeting specific SSTR subtypes.

Role of plasma fatty acid in age-related macular degeneration: insights from a mendelian randomization analysis.

BACKGROUND: An imbalance in lipid metabolism has been linked to the development of AMD, but the causal relationship between AMD and plasma fatty acids (FAs) remains controversial. Using a two-sample Mendelian randomization (MR) approach, we sought to evaluate the impact of specific FA plasma levels on the risk of different AMD subtypes. METHODS: We analysed genome-wide association data of circulating FAs from 115,006 European-descended individuals in the UK Biobank. These data were used in a two-sample MR framework to assess the potential role of circulating FAs in developing wet and dry AMD. Sensitivity analyses were conducted to ensure the robustness of our findings. Additional multivariable and locus-specific MR analyses were conducted to evaluate direct effects of FA on AMD subtypes, minimizing biases from lipoprotein-related traits and triglycerides. RESULTS: Mendelian randomization revealed associations of omega-3 was associated with decreased wet (OR 0.78, 95%CI 0.66-0.92) and dry AMD (0.85, 0.74-0.97) risk, showed a protective effect on AMD. Notably, the omega-6 to omega-3 ratio showed potential causal effects on both wet (1.27, 1.03-1.56) and dry AMD (1.18, 1.02-1.37). Multivariable MR suggested that the causal relationship of omega-3, omega-6 to omega-3 ratio on wet AMD persists after conditioning on HDL, LDL and triglycerides, albeit with slightly diminished evidence strength. Locus-specific MR linked to omega-3(FADS1, 0.89, 0.82-0.98; FADS2, 0.88, 0.81-0.96) and omega-6 to omega-3 ratio (FADS1, 1.10, 1.02-1.20; FADS2, 1.11, 1.03-1.20) suggests causal effects of these factors on wet AMD. CONCLUSIONS: The associations between plasma FA concentrations and AMD, suggest potential causal role of omega-3, and the omega-6 to omega-3 ratio in wet AMD. These results underscore the impact of an imbalanced circulating omega-3 and omega-6 FA ratio on AMD pathophysiology from MR perspective.

[Phenotypic drug discovery promotes research and development of innovative drugs based on traditional Chinese medicine].

Traditional Chinese medicine with rich resources in China and definite therapeutic effects on complex diseases demonstrates great development potential. However, the complex composition, the unclear pharmacodynamic substances and mechanisms of action, and the lack of reasonable methods for evaluating clinical safety and efficacy have limited the research and development of innovative drugs based on traditional Chinese medicine. The progress in cutting-edge disciplines such as artificial intelligence and biomimetics, especially the emergence of cell painting and organ-on-a-chip, helps to identify and characterize the active ingredients in traditional Chinese medicine based on the changes in model characteristics, thus providing more accurate guidance for the development and application of traditional Chinese medicine. The application of phenotypic drug discovery in the research and development of innovative drugs based on traditional Chinese medicine is gaining increasing attention. In recent years, the technology for phenotypic drug discovery keeps advancing, which improves the early discovery rate of new drugs and the success rate of drug research and development. Accordingly, phenotypic drug discovery gradually becomes a key tool for the research on new drugs. This paper discusses the enormous potential of traditional Chinese medicine in the discovery and development of innovative drugs and illustrates how the application of phenotypic drug discovery, supported by cutting-edge technologies such as cell painting, deep learning, and organ-on-a-chip, propels traditional Chinese medicine into a new stage of development.