👤 Bharathi Manjunath

Cholesteryl ester transfer protein (CETP) plays a central role in plasma lipid transport, facilitating the exchange of neutral lipids, such as cholesteryl esters and triglycerides, between lipoproteins. Despite the existence of several lipid-carrying/binding proteins in the family, such as lipopolysaccharide-binding protein (LBP), bacterial permeability increasing protein (BPI), and phospholipid transfer protein (PLTP), the structural and mechanistic uniqueness of CETP in neutral lipid transfer remains underexplored. Moreover, the involvement of PLTP in neutral lipid transfer is still debated, with researchers presenting conflicting mechanisms. Therefore, this study investigates the distinct structural ability of CETP in mediating neutral lipid exchange compared to other lipid-binding proteins. The study also emphasizes that simple protein modeling based on templates may not guarantee structural integrity unless validated through simulations. To achieve our objectives, we employed molecular docking, comparative molecular dynamics simulations, structural analysis, and lipid-protein interaction profiling with representative neutral lipids. In addition, protein-lipid affinities, tunnel architecture, and conformational flexibility were examined to characterize CETP's unique features and evaluate the quality of the constructed model for PLTP. The results demonstrated that a tunnel-like hydrophobic channel in CETP facilitates bidirectional neutral lipid transfer, unlike the compartmentalized binding pockets observed in other proteins. In addition, the neutral lipids' unfavorable conformational orientation was not affected in PLTP, whereas the same unfavorable conformation is changed to a favorable conformation in CETP, making only the lipid-carrying protein have the ability to transfer the neutral lipids. In conclusion, our findings highlight that the CETP is a specialized neutral lipid carrier with a unique structural mechanism distinct from typical lipid-binding proteins. This comparative insight enhances understanding of the structural plasticity of each lipid-carrying protein and the reliability of the modeled structure. Show less

Introduction Recently, the expression of metallophosphoesterase-domain-containing protein 2 (MPPED2) was identified in cervical cancer. However, its precise role and correlation with other tumor suppressor proteins, such as p16INK4A, is not well studied in high-risk human papillomavirus (HPV) integrated human cervical carcinoma. Hence, in the present study, we try to see the expression of MPPED2 in human cervical carcinoma and its correlation with age and p16INK4A protein expression level. Methods The prospective study consists of 200 samples of 150 known cervical carcinoma and 50 controls. Histopathological evaluation, immunohistochemical staining, and semi-quantitative scoring of the intensity of proteins were performed. Statistical analysis was performed with the Shapiro-Wilk test, Spearman's rho correlation sig. (two-tailed), and Student's t-test. Results The data show that among the 150 cases, 136 (68.0%) cervical carcinoma tissues express the presence of high-risk HPV viral genome integration in the host cell. The expression of p16INK4A protein is higher in those tissues identified with high-risk HPV viral genomes. In contrast, the expression of MPPED2 protein is lesser or absent in those cervical tissues that have the higher expression of p16INK4A protein and vice versa. There is a significant correlation (p=0.000) between age and p16INK4A protein expression but not with MPPED2. A significant linear correlation (p=0.000) is found between the p16INK4A and MPPED2 proteins. Conclusion It may support the therapeutic application of MPPED2 protein to prevent cervical carcinoma progression in the near future. Show less