1
|
Affiliation(s)
- Raúl A Marinelli
- Institute of Experimental Physiology, National Council of Scientific and Technological Research, School of Biochemical Sciences, National University of Rosario, Rosario, Argentina
| | - Julieta Marrone
- Institute of Experimental Physiology, National Council of Scientific and Technological Research, School of Biochemical Sciences, National University of Rosario, Rosario, Argentina
| |
Collapse
|
2
|
Affiliation(s)
- James L Boyer
- Department of Medicine and Liver Center, Yale University School of Medicine, New Haven, Connecticut.
| |
Collapse
|
3
|
Matsumoto K, Imasato M, Yamazaki Y, Tanaka H, Watanabe M, Eguchi H, Nagano H, Hikita H, Tatsumi T, Takehara T, Tamura A, Tsukita S. Claudin 2 deficiency reduces bile flow and increases susceptibility to cholesterol gallstone disease in mice. Gastroenterology 2014; 147:1134-45.e10. [PMID: 25068494 DOI: 10.1053/j.gastro.2014.07.033] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Revised: 07/10/2014] [Accepted: 07/19/2014] [Indexed: 01/09/2023]
Abstract
BACKGROUND & AIMS Bile formation and secretion are essential functions of the hepatobiliary system. Bile flow is generated by transepithelial transport of water and ionic/nonionic solutes via transcellular and paracellular pathways that is mainly driven by osmotic pressure. We examined the role of tight junction-based paracellular transport in bile secretion. Claudins are cell-cell adhesion molecules in tight junctions that create the paracellular barrier. The claudin family has 27 reported members, some of which have paracellular ion- and/or water-channel-like functions. Claudin 2 is a paracellular channel-forming protein that is highly expressed in hepatocytes and cholangiocytes; we examined the hepatobiliary system of claudin 2 knockout (Cldn2(-/-)) mice. METHODS We collected liver and biliary tissues from Cldn2(-/-) and Cldn2(+/+) mice and performed histologic, biochemical, and electrophysiologic analyses. We measured osmotic movement of water and/or ions in Cldn2(-/-) and Cldn2(+/+) hepatocytes and bile ducts. Mice were placed on lithogenic diets for 4 weeks and development of gallstone disease was assessed. RESULTS The rate of bile flow in Cldn2(-/-) mice was half that of Cldn2(+/+) mice, resulting in significantly more concentrated bile in livers of Cldn2(-/-) mice. Consistent with these findings, osmotic gradient-driven water flow was significantly reduced in hepatocyte bile canaliculi and bile ducts isolated from Cldn2(-/-) mice, compared with Cldn2(+/+) mice. After 4 weeks on lithogenic diets, all Cldn2(-/-) mice developed macroscopically visible gallstones; the main component of the gallstones was cholesterol (>98%). In contrast, none of the Cldn2(+/+) mice placed on lithogenic diets developed gallstones. CONCLUSIONS Based on studies of Cldn2(-/-) mice, claudin 2 regulates paracellular ion and water flow required for proper regulation of bile composition and flow. Dysregulation of this process increases susceptibility to cholesterol gallstone disease in mice.
Collapse
Affiliation(s)
- Kengo Matsumoto
- Laboratory of Biological Science, Graduate School of Frontier Biosciences and Graduate School of Medicine, Osaka University, Osaka, Japan; Department of Gastroenterology and Hepatology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Mitsunobu Imasato
- Laboratory of Biological Science, Graduate School of Frontier Biosciences and Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Yuji Yamazaki
- Laboratory of Biological Science, Graduate School of Frontier Biosciences and Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Hiroo Tanaka
- Laboratory of Biological Science, Graduate School of Frontier Biosciences and Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Mitsuhiro Watanabe
- Department of Internal Medicine, School of Medicine, Keio University, Tokyo, Japan; Graduate School of Media and Governance, Faculty of Environment and Information Studies, Keio University, Kanagawa, Japan
| | - Hidetoshi Eguchi
- Department of Surgery, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Hiroaki Nagano
- Department of Surgery, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Hayato Hikita
- Department of Gastroenterology and Hepatology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Tomohide Tatsumi
- Department of Gastroenterology and Hepatology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Tetsuo Takehara
- Department of Gastroenterology and Hepatology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Atsushi Tamura
- Laboratory of Biological Science, Graduate School of Frontier Biosciences and Graduate School of Medicine, Osaka University, Osaka, Japan.
| | - Sachiko Tsukita
- Laboratory of Biological Science, Graduate School of Frontier Biosciences and Graduate School of Medicine, Osaka University, Osaka, Japan.
| |
Collapse
|
4
|
Marrone J, Lehmann GL, Soria LR, Pellegrino JM, Molinas S, Marinelli RA. Adenoviral transfer of human aquaporin -1 gene to rat liver improves bile flow in estrogen-induced cholestasis. Gene Ther 2014; 21:1058-64. [DOI: 10.1038/gt.2014.78] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Revised: 07/01/2014] [Accepted: 07/09/2014] [Indexed: 12/29/2022]
|
5
|
Levitt DG, Levitt MD. Quantitative assessment of the multiple processes responsible for bilirubin homeostasis in health and disease. Clin Exp Gastroenterol 2014; 7:307-28. [PMID: 25214800 PMCID: PMC4159128 DOI: 10.2147/ceg.s64283] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Serum bilirubin measurements are commonly obtained for the evaluation of ill patients and to screen for liver disease in routine physical exams. An enormous research effort has identified the multiple mechanisms involved in the production and metabolism of conjugated (CB) and unconjugated bilirubin (UB). While the qualitative effects of these mechanisms are well understood, their expected quantitative influence on serum bilirubin homeostasis has received less attention. In this review, each of the steps involved in bilirubin production, metabolism, hepatic cell uptake, and excretion is quantitatively examined. We then attempt to predict the expected effect of normal and defective function on serum UB and CB levels in health and disease states including hemolysis, extra- and intrahepatic cholestasis, hepatocellular diseases (eg, cirrhosis, hepatitis), and various congenital defects in bilirubin conjugation and secretion (eg, Gilbert's, Dubin-Johnson, Crigler-Najjar, Rotor syndromes). Novel aspects of this review include: 1) quantitative estimates of the free and total UB and CB in the plasma, hepatocyte, and bile; 2) detailed discussion of the important implications of the recently recognized role of the hepatic OATP transporters in the maintenance of CB homeostasis; 3) discussion of the differences between the standard diazo assay versus chromatographic measurement of CB and UB; 4) pharmacokinetic implications of the extremely high-affinity albumin binding of UB; 5) role of the enterohepatic circulation in physiologic jaundice of newborn and fasting hyperbilirubinemia; and 6) insights concerning the clinical interpretation of bilirubin measurements.
Collapse
Affiliation(s)
- David G Levitt
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA
| | - Michael D Levitt
- Research Service, Veterans Affairs Medical Center, Minneapolis, MN, USA
| |
Collapse
|
6
|
Abstract
Bile is a unique and vital aqueous secretion of the liver that is formed by the hepatocyte and modified down stream by absorptive and secretory properties of the bile duct epithelium. Approximately 5% of bile consists of organic and inorganic solutes of considerable complexity. The bile-secretory unit consists of a canalicular network which is formed by the apical membrane of adjacent hepatocytes and sealed by tight junctions. The bile canaliculi (∼1 μm in diameter) conduct the flow of bile countercurrent to the direction of portal blood flow and connect with the canal of Hering and bile ducts which progressively increase in diameter and complexity prior to the entry of bile into the gallbladder, common bile duct, and intestine. Canalicular bile secretion is determined by both bile salt-dependent and independent transport systems which are localized at the apical membrane of the hepatocyte and largely consist of a series of adenosine triphosphate-binding cassette transport proteins that function as export pumps for bile salts and other organic solutes. These transporters create osmotic gradients within the bile canalicular lumen that provide the driving force for movement of fluid into the lumen via aquaporins. Species vary with respect to the relative amounts of bile salt-dependent and independent canalicular flow and cholangiocyte secretion which is highly regulated by hormones, second messengers, and signal transduction pathways. Most determinants of bile secretion are now characterized at the molecular level in animal models and in man. Genetic mutations serve to illuminate many of their functions.
Collapse
Affiliation(s)
- James L Boyer
- Department of Medicine and Liver Center, Yale University School of Medicine, New Haven, Connecticut, USA.
| |
Collapse
|
7
|
Reshetnyak VI. Physiological and molecular biochemical mechanisms of bile formation. World J Gastroenterol 2013; 19:7341-7360. [PMID: 24259965 PMCID: PMC3831216 DOI: 10.3748/wjg.v19.i42.7341] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 07/17/2013] [Accepted: 09/29/2013] [Indexed: 02/06/2023] Open
Abstract
This review considers the physiological and molecular biochemical mechanisms of bile formation. The composition of bile and structure of a bile canaliculus, biosynthesis and conjugation of bile acids, bile phospholipids, formation of bile micellar structures, and enterohepatic circulation of bile acids are described. In general, the review focuses on the molecular physiology of the transporting systems of the hepatocyte sinusoidal and apical membranes. Knowledge of physiological and biochemical basis of bile formation has implications for understanding the mechanisms of development of pathological processes, associated with diseases of the liver and biliary tract.
Collapse
|
8
|
Soria LR, Marrone J, Calamita G, Marinelli RA. Ammonia detoxification via ureagenesis in rat hepatocytes involves mitochondrial aquaporin-8 channels. Hepatology 2013; 57:2061-71. [PMID: 23299935 DOI: 10.1002/hep.26236] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Accepted: 11/27/2012] [Indexed: 12/26/2022]
Abstract
UNLABELLED Hepatocyte mitochondrial ammonia detoxification via ureagenesis is critical for the prevention of hyperammonemia and hepatic encephalopathy. Aquaporin-8 (AQP8) channels facilitate the membrane transport of ammonia. Because AQP8 is expressed in hepatocyte inner mitochondrial membranes (IMMs), we studied whether mitochondrial AQP8 (mtAQP8) plays a role in ureagenesis from ammonia. Primary cultured rat hepatocytes were transfected with small interfering RNAs (siRNAs) targeting two different regions of the rat AQP8 molecule or with scrambled control siRNA. After 48 hours, the levels of mtAQP8 protein decreased by approximately 80% (P < 0.05) without affecting cell viability. mtAQP8 knockdown cells in the presence of ammonium chloride showed a decrease in ureagenesis of approximately 30% (P < 0.05). Glucagon strongly stimulated ureagenesis in control hepatocytes (+120%, P < 0.05) but induced no significant stimulation in mtAQP8 knockdown cells. Contrarily, mtAQP8 silencing induced no significant change in basal and glucagon-induced ureagenesis when glutamine or alanine was used as a source of nitrogen. Nuclear magnetic resonance studies using 15N-labeled ammonia confirmed that glucagon-induced 15N-labeled urea synthesis was markedly reduced in mtAQP8 knockdown hepatocytes (-90%, P < 0.05). In vivo studies in rats showed that under glucagon-induced ureagenesis, hepatic mtAQP8 protein expression was markedly up-regulated (+160%, P < 0.05). Moreover, transport studies in liver IMM vesicles showed that glucagon increased the diffusional permeability to the ammonia analog [(14) C]methylamine (+80%, P < 0.05). CONCLUSION Hepatocyte mtAQP8 channels facilitate the mitochondrial uptake of ammonia and its metabolism into urea, mainly under glucagon stimulation. This mechanism may be relevant to hepatic ammonia detoxification and in turn, avoid the deleterious effects of hyperammonemia.
Collapse
Affiliation(s)
- Leandro R Soria
- Instituto de Fisiología Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | | | | | | |
Collapse
|
9
|
Rectification of the water permeability in COS-7 cells at 22, 10 and 0°C. PLoS One 2011; 6:e23643. [PMID: 21887290 PMCID: PMC3161049 DOI: 10.1371/journal.pone.0023643] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Accepted: 07/21/2011] [Indexed: 11/19/2022] Open
Abstract
The osmotic and permeability parameters of a cell membrane are essential physico-chemical properties of a cell and particularly important with respect to cell volume changes and the regulation thereof. Here, we report the hydraulic conductivity, L(p), the non-osmotic volume, V(b), and the Arrhenius activation energy, E(a), of mammalian COS-7 cells. The ratio of V(b) to the isotonic cell volume, V(c iso), was 0.29. E(a), the activation energy required for the permeation of water through the cell membrane, was 10,700, and 12,000 cal/mol under hyper- and hypotonic conditions, respectively. Average values for L(p) were calculated from swell/shrink curves by using an integrated equation for L(p). The curves represented the volume changes of 358 individually measured cells, placed into solutions of nonpermeating solutes of 157 or 602 mOsm/kg (at 0, 10 or 22°C) and imaged over time. L(p) estimates for all six combinations of osmolality and temperature were calculated, resulting in values of 0.11, 0.21, and 0.10 µm/min/atm for exosmotic flow and 0.79, 1.73 and 1.87 µm/min/atm for endosmotic flow (at 0, 10 and 22°C, respectively). The unexpected finding of several fold higher L(p) values for endosmotic flow indicates highly asymmetric membrane permeability for water in COS-7. This phenomenon is known as rectification and has mainly been reported for plant cell, but only rarely for animal cells. Although the mechanism underlying the strong rectification found in COS-7 cells is yet unknown, it is a phenomenon of biological interest and has important practical consequences, for instance, in the development of optimal cryopreservation.
Collapse
|