👤 Raja Bhattacharyya

Hepatobiliary cancers (HBCs) pose a major global health challenge, with a lack of effective targeted biomarkers. Due to their complex anatomical locations, shared risk factors, and the limitations of targeted therapies, generalized treatment strategies are often used for gallbladder cancer (GBC), hepatocellular carcinoma (HCC), and intrahepatic cholangiocarcinoma (ICC). This study aimed to identify specific transcriptomic signatures in GBC, HCC, and ICC. The transcriptomic data analysis revealed distinct expression profiles, highlighting complex molecular heterogeneity within these cancers, even within the same organ system. Functional annotation revealed distinct biological pathways associated with each type of HBCs. GBC was linked to cell cycle regulation, HCC was associated with immune system modulation, and ICC was involved in metabolic dysregulation, particularly lipid metabolism. Gene co-expression network (GCN) and protein-protein interaction (PPI) network analyses identified potential key genes, such as MAPK3 and ERBB2 in GBC, AC069287.1 and ACTN2 in HCC, and TRPC1 and BACE1 in ICC. The FOX family of transcription factors (TFs) was conserved across all three cancer types. To further explore the relationship between Epithelial-Mesenchymal Transition (EMT) and the identified hub genes and TFs, an EMT score analysis was conducted. This analysis revealed distinct phenotypic characteristics in each cancer type, with TFs identified in GBC and ICC showing a stronger correlation with EMT compared to those in HCC. External validation using The Cancer Genome Atlas (TCGA) databases confirmed the expression of candidate genes, underscoring their potential as therapeutic targets. These findings provide valuable insights into the molecular heterogeneity and complexity of HBCs, opening new avenues for personalized therapeutic interventions. Show less

Palmitoylation, a lipid-based posttranslational protein modification, plays a crucial role in regulating various aspects of neuronal function through altering protein membrane-targeting, stabilities, and protein-protein interaction profiles. Disruption of palmitoylation has recently garnered attention as disease mechanism in neurodegeneration. Many proteins implicated in neurodegenerative diseases and associated neuronal dysfunction, including but not limited to amyloid precursor protein, β-secretase (BACE1), postsynaptic density protein 95, Fyn, synaptotagmin-11, mutant huntingtin, and mutant superoxide dismutase 1, undergo palmitoylation, and recent evidence suggests that altered palmitoylation contributes to the pathological characteristics of these proteins and associated disruption of cellular processes. In addition, dysfunction of enzymes that catalyze palmitoylation and depalmitoylation has been connected to the development of neurological disorders. This review highlights some of the latest advances in our understanding of palmitoylation regulation in neurodegenerative diseases and explores potential therapeutic implications. Show less

Enzymes play a vital role in life processes; they control chemical reactions and allow functional cycles to be synchronized. Many enzymes harness large-scale motions of their domains to achieve tremendous catalytic prowess and high selectivity for specific substrates. One outstanding example is provided by the three-domain enzyme adenylate kinase (AK), which catalyzes phosphotransfer between ATP to AMP. Here we study the phenomenon of substrate inhibition by AMP and its correlation with domain motions. Using single-molecule FRET spectroscopy, we show that AMP does not block access to the ATP binding site, neither by competitive binding to the ATP cognate site nor by directly closing the LID domain. Instead, inhibitory concentrations of AMP lead to a faster and more cooperative domain closure by ATP, leading in turn to an increased population of the closed state. The effect of AMP binding can be modulated through mutations throughout the structure of the enzyme, as shown by the screening of an extensive AK mutant library. The mutation of multiple conserved residues reduces substrate inhibition, suggesting that substrate inhibition is an evolutionary well conserved feature in AK. Combining these insights, we developed a model that explains the complex activity of AK, particularly substrate inhibition, based on the experimentally observed opening and closing rates. Notably, the model indicates that the catalytic power is affected by the microsecond balance between the open and closed states of the enzyme. Our findings highlight the crucial role of protein motions in enzymatic activity. Show less