Fetal liver development and implications for liver disease pathogenesis

Supplementation with dimethylglycine sodium salt improves lipid metabolism disorder in intrauterine growth-retarded pigs

This study aims to elucidate the mechanism of lipid metabolism disorder in intrauterine growth retardation (IUGR) pigs and the potential alleviating effects of dimethylglycine sodium salt (DMG-Na). A total of 60 male newborn piglets were selected for this study. Within each litter, one normal birth weight (NBW) male piglet (1.53 ± 0.04 kg) and two IUGR male piglets (0.76 ± 0.06 kg) were chosen based on their birth weight. The piglets were divided into three groups for the study: NBW pigs received a PBS gavage and a common basal diet (NBW-C group), IUGR pigs received the same PBS gavage and common basal diet (IUGR-C group), and IUGR pigs received a 70-mg DMG-Na gavage along with a common basal diet supplemented with 0.1% DMG-Na (IUGR-D group). At 150 d of age, all piglets underwent euthanasia by exsanguination following electrical stunning, after which plasma, liver, and longissimus dorsi (LM) samples were promptly collected. The IUGR-D group demonstrated improvements in plasma parameters (P < 0.05), with lower triglyceride and free fatty acid (FFA) values, and hormone levels (P < 0.05), with lower growth hormone, insulin, and homeostasis model assessment of insulin resistance values. Restoration of lipid metabolism was observed (P < 0.05), with lower triglyceride and FFA, and higher hepatic lipase and total lipase values in the liver, and lower triglyceride and FFA values in the LM. Mitochondrial ETC complexes showed increased levels (P < 0.05), including higher complex III values in the liver, and higher complex I, complex III, and complex V values in the LM. Enhanced levels of energy metabolites were noted (P < 0.05), with higher NAD+, NAD+/NADH, adenosine triphosphate, and mtDNA values, and lower NADH values in the liver and LM. Additionally, meat quality parameters showed improvement (P < 0.05), with higher pH 24 h and a∗ values, and lower drip loss 48 h, L∗, and b∗ values. The expressions of lipid metabolism and mitochondrial function-related genes and proteins were upregulated (P < 0.05) compared to the IUGR-C group. In conclusion, it was indicated that IUGR pigs experienced lipid metabolism disorders and diminished performance. However, supplementation with DMG-Na showed promise in mitigating these adverse physiological effects by safeguarding body tissues and modulating energy metabolism.

ADAMTS18-fibronectin interaction regulates the morphology of liver sinusoidal endothelial cells

Liver sinusoidal endothelial cells (LSECs) have a unique morphological structure known as "fenestra" that plays a crucial role in liver substance exchange and homeostasis maintenance. In this study, we demonstrate that ADAMTS18 protease is primarily secreted by fetal liver endothelial cells. ADAMTS18 deficiency leads to enlarged fenestrae and increased porosity of LSECs, microthrombus formation in liver vessels, and an imbalance of liver oxidative stress. These defects worsen carbon tetrachloride (CCl4)-induced liver fibrosis and diethylnitrosamine (DEN)/high-fat-induced hepatocellular carcinoma (HCC) in adult Adamts18-deficient mice. Mechanically, ADAMTS18 functions as a modifier of fibronectin (FN) to regulate the morphological acquisition of LSECs via the vascular endothelial growth factor A (VEGFA) signaling pathways. Collectively, a mechanism is proposed for LSEC morphogenesis and liver homeostasis maintenance via ADAMTS18-FN-VEGFA niches.

Generation of a biliary tract cancer cell line atlas reveals molecular subtypes and therapeutic targets

Biliary tract cancers (BTCs) are a group of deadly malignancies encompassing intrahepatic and extrahepatic cholangiocarcinoma, gallbladder carcinoma, and ampullary carcinoma. Here, we present the integrative analysis of 63 BTC cell lines via multi-omics clustering and genome- scale CRISPR screens, providing a platform to illuminate BTC biology and inform therapeutic development. We identify dependencies broadly enriched in BTC compared to other cancers as well as dependencies selective to the anatomic subtypes. Notably, cholangiocarcinoma cell lines are stratified into distinct lineage subtypes based on biliary or dual biliary/hepatocyte marker signatures, associated with dependency on specific lineage survival factors. Transcriptional analysis of patient specimens demonstrates the prognostic significance of these lineage subtypes. Additionally, we delineate strategies to enhance targeted therapies or to overcome resistance in cell lines with key driver gene mutations. Furthermore, clustering based on dependencies and proteomics data elucidates unexpected functional relationships, including a BTC subgroup with partial squamous differentiation. Thus, this cell line atlas reveals potential therapeutic targets in molecularly defined BTCs, unveils biologically distinct disease subtypes, and offers a vital resource for BTC research.

Unveiling the power of microenvironment in liver regeneration: an in-depth overview

The liver serves as a vital regulatory hub for various physiological processes, including sugar, protein, and fat metabolism, coagulation regulation, immune system maintenance, hormone inactivation, urea metabolism, and water-electrolyte acid-base balance control. These functions rely on coordinated communication among different liver cell types, particularly within the liver's fundamental hepatic lobular structure. In the early stages of liver development, diverse liver cells differentiate from stem cells in a carefully orchestrated manner. Despite its susceptibility to damage, the liver possesses a remarkable regenerative capacity, with the hepatic lobule serving as a secure environment for cell division and proliferation during liver regeneration. This regenerative process depends on a complex microenvironment, involving liver resident cells, circulating cells, secreted cytokines, extracellular matrix, and biological forces. While hepatocytes proliferate under varying injury conditions, their sources may vary. It is well-established that hepatocytes with regenerative potential are distributed throughout the hepatic lobules. However, a comprehensive spatiotemporal model of liver regeneration remains elusive, despite recent advancements in genomics, lineage tracing, and microscopic imaging. This review summarizes the spatial distribution of cell gene expression within the regenerative microenvironment and its impact on liver regeneration patterns. It offers valuable insights into understanding the complex process of liver regeneration.

MicroRNA breed and parent-of-origin effects provide insights into biological pathways differentiating cattle subspecies in fetal liver

Introduction: MicroRNAs (miRNAs) play a crucial role in regulating gene expression during key developmental processes, including fetal development. Brahman (Bos taurus indicus) and Angus (Bos taurus taurus) cattle breeds represent two major cattle subspecies with strikingly different phenotypes. Methods: We analyzed miRNA expression in liver samples of purebred and reciprocal crosses of Angus and Brahman to investigate breed and parent-of-origin effects at the onset of accelerated fetal growth. Results: We identified eight novel miRNAs in fetal liver samples and 14 differentially expressed miRNAs (DEMs) between purebred samples. Correlation of gene expression modules and miRNAs by breed and parent-of-origin effects revealed an enrichment of genes associated with breed-specific differences in traits such as heat tolerance (Brahman) and fat deposition (Angus). We demonstrate that genes predicted to be targets of DEMs were more likely to be differentially expressed than non-targets (p-value < 0.05). We identified several miRNAs (bta-miR-187, bta-miR-216b, bta-miR-2284c, bta-miR-2285c, bta-miR-2285cp, bta-miR-2419-3p, bta-miR-2419-5p, and bta-miR-11984) that showed similar correlation patterns as bta-miR-2355-3p, which has been associated with the glutamatergic synapse pathway, a key facilitator of heat tolerance. Furthermore, we report Angus-breed-specific miRNAs (bta-miR-2313-5p, btamiR-490, bta-miR-2316, and bta-miR-11990) that may be involved in fat deposition. Finally, we showed that the DEMs identified in fetal liver are involved in Rap1, MAPK, and Ras signalling pathways, which are important for fetal development, muscle development and metabolic traits such as fat metabolism. Conclusion: Our work sheds light on the miRNA expression patterns that contribute to gene expression differences driving phenotypic differences in indicine and taurine cattle.

Chronic metabolic stress drives developmental programs and loss of tissue functions in non-transformed liver that mirror tumor states and stratify survival

Under chronic stress, cells must balance competing demands between cellular survival and tissue function. In metabolic dysfunction-associated steatotic liver disease (MASLD, formerly NAFLD/NASH), hepatocytes cooperate with structural and immune cells to perform crucial metabolic, synthetic, and detoxification functions despite nutrient imbalances. While prior work has emphasized stress-induced drivers of cell death, the dynamic adaptations of surviving cells and their functional repercussions remain unclear. Namely, we do not know which pathways and programs define cellular responses, what regulatory factors mediate (mal)adaptations, and how this aberrant activity connects to tissue-scale dysfunction and long-term disease outcomes. Here, by applying longitudinal single-cell multi -omics to a mouse model of chronic metabolic stress and extending to human cohorts, we show that stress drives survival-linked tradeoffs and metabolic rewiring, manifesting as shifts towards development-associated states in non-transformed hepatocytes with accompanying decreases in their professional functionality. Diet-induced adaptations occur significantly prior to tumorigenesis but parallel tumorigenesis-induced phenotypes and predict worsened human cancer survival. Through the development of a multi -omic computational gene regulatory inference framework and human in vitro and mouse in vivo genetic perturbations, we validate transcriptional (RELB, SOX4) and metabolic (HMGCS2) mediators that co-regulate and couple the balance between developmental state and hepatocyte functional identity programming. Our work defines cellular features of liver adaptation to chronic stress as well as their links to long-term disease outcomes and cancer hallmarks, unifying diverse axes of cellular dysfunction around core causal mechanisms.

Endothelial cell SMAD6 balances Alk1 function to regulate adherens junctions and hepatic vascular development

BMP signaling is crucial to blood vessel formation and function, but how pathway components regulate vascular development is not well-understood. Here, we find that inhibitory SMAD6 functions in endothelial cells to negatively regulate ALK1-mediated responses, and it is required to prevent vessel dysmorphogenesis and hemorrhage in the embryonic liver vasculature. Reduced Alk1 gene dosage rescued embryonic hepatic hemorrhage and microvascular capillarization induced by Smad6 deletion in endothelial cells in vivo. At the cellular level, co-depletion of Smad6 and Alk1 rescued the destabilized junctions and impaired barrier function of endothelial cells depleted for SMAD6 alone. Mechanistically, blockade of actomyosin contractility or increased PI3K signaling rescued endothelial junction defects induced by SMAD6 loss. Thus, SMAD6 normally modulates ALK1 function in endothelial cells to regulate PI3K signaling and contractility, and SMAD6 loss increases signaling through ALK1 that disrupts endothelial cell junctions. ALK1 loss-of-function also disrupts vascular development and function, indicating that balanced ALK1 signaling is crucial for proper vascular development and identifying ALK1 as a 'Goldilocks' pathway in vascular biology that requires a certain signaling amplitude, regulated by SMAD6, to function properly.

Whole Liver Derived Acellular Extracellular Matrix for Bioengineering of Liver Constructs: An Updated Review

Biomaterial templates play a critical role in establishing and bioinstructing three-dimensional cellular growth, proliferation and spatial morphogenetic processes that culminate in the development of physiologically relevant in vitro liver models. Various natural and synthetic polymeric biomaterials are currently available to construct biomimetic cell culture environments to investigate hepatic cell-matrix interactions, drug response assessment, toxicity, and disease mechanisms. One specific class of natural biomaterials consists of the decellularized liver extracellular matrix (dECM) derived from xenogeneic or allogeneic sources, which is rich in bioconstituents essential for the ultrastructural stability, function, repair, and regeneration of tissues/organs. Considering the significance of the key design blueprints of organ-specific acellular substrates for physiologically active graft reconstruction, herein we showcased the latest updates in the field of liver decellularization-recellularization technologies. Overall, this review highlights the potential of acellular matrix as a promising biomaterial in light of recent advances in the preparation of liver-specific whole organ scaffolds. The review concludes with a discussion of the challenges and future prospects of liver-specific decellularized materials in the direction of translational research.