Roland Reinehr - Academia.edu (original) (raw)
Papers by Roland Reinehr
Clinical Hemorheology and Microcirculation, 2019
Colon cancer cells cultured under hyperosmotic conditions as in vitro model to investigate dehydr... more Colon cancer cells cultured under hyperosmotic conditions as in vitro model to investigate dehydration effects on cancer drug susceptibility
Insulin is known to induce hepatocyte swelling, which triggers via integrins and c-Src kinase an ... more Insulin is known to induce hepatocyte swelling, which triggers via integrins and c-Src kinase an activation of the epidermal growth factor receptor (EGFR) and subsequent cell proliferation (1). Free fatty acids (FFAs) are known to induce lipoapoptosis in liver cells in a c-Jun-NH2terminal kinase (JNK)-dependent, but death receptor-independent way (2). As nonalcoholic steatohepatitis (NASH) is associated with hyperinsulinemia and increased FFAblood levels, the interplay between insulin and FFA was studied with regard to hepatocyte proliferation and apoptosis in isolated rat and mouse hepatocytes. Saturated long chain FFAs induced apoptosis and JNK activation in primary rat hepatocytes, but did not activate the CD95 (Fas, APO-1) system, whereas insulin triggered EGFR activation and hepatocyte proliferation. Coadministration of insulin and FFAs, however, abolished hepatocyte proliferation and triggered CD95-dependent apoptosis due to a JNK-dependent association of the activated EGFR wi...
![Research paper thumbnail of [668] the Membrane Bound Bile Salt Receptor TGR5 is Expressed in Kupffer Cells of Rat and Human Liver](https://attachments.academia-assets.com/84944637/thumbnails/1.jpg)
](Journal of Hepatology, 2007
Journal of Hepatology, 2003
Journal of Hepatology, 1998
Hepatology, 1999
The effects of perivascular nerve stimulation and phenylephrine on osmolyte release were studied ... more The effects of perivascular nerve stimulation and phenylephrine on osmolyte release were studied in the intact perfused rat liver and isolated liver parenchymal cells (PC) and nonparenchymal cells. In the perfused liver, electrical stimulation of perivascular nerves (20 Hz/2 ms/20 V) led to a phentolamine-sensitive increase of cell hydration by 6.5% ؎ 1.2% (n ؍ 3) and a transient phentolaminesensitive stimulation of taurine and inositol, but not betaine, release. These nerve effects were mimicked by phenylephrine, but not prostaglandin F 2␣ , and were not affected by sodium nitroprusside (SNP) or ibuprofen. Nerve stimulationinduced taurine, but not inositol, release was inhibited by 4,4Ј-di-isothiocyanatostilbene-2,2Ј-disulphonic acid (DIDS) (50 mol/L). Single-cell fluorescence studies with isolated liver PC, Kupffer cells (KC), sinusoidal endothelial cells (SEC), and hepatic stellate cells (HSC) revealed that phenylephrine induced an increase in cytosolic free Ca 2؉ only in PC and HSC, but not in KC and SEC, whereas extracellular uridine triphosphate (UTP) produced Ca 2؉ transients/ oscillations in all liver cell types studied. Phenylephrine had no effect on osmolyte release from isolated KC and SEC, but increased taurine (but not inositol) release from PC and inositol (but not taurine) efflux from HSC. The data suggest that: 1) liver cell hydration and-consecutivelyosmolyte content are modulated by hepatic nerves via an ␣-adrenergic mechanism, which does not involve eicosanoids or hemodynamic changes; 2) that PC and HSC are the primary targets for nerve-dependent ␣-adrenergic activation, whereas 3) KC and SEC probably do not express ␣-adrenoceptors coupled to Ca 2؉ mobilization or osmolyte efflux. (HEPATOLOGY 1999;29:195-204.) In rat liver, many metabolic processes such as glycogen metabolism, urea and glutamine formation, bile excretion, ketogenesis, oxygen consumption, transferrin biosynthesis/ excretion, and cellular ion balance are under control of the nervous system 1-9 (reviewed in Shimazu 10 and Jungermann 11). These nerve effects are largely mediated by ␣-adrenergic mechanisms, but also involve secondary effects of eicosanoids, which are formed in response to nerve stimulation and play a role in the intercellular communication in the liver acinus. 11-13 In the rat liver, the propagation of the neural signal requires intact intercellular gap junctions. 14,15 Another determinant of metabolic liver function is the hydration state of liver cells and the availability of organic osmolytes for the different hepatocyte populations (reviewed in Häussinger 16-18). These organic osmolytes, such as taurine, betaine, and inositol, are accumulated within or released from the cells in response to osmotic stress. Whereas taurine, betaine, and inositol are important osmolytes in nonparenchymal liver cells, the major osmolyte of the liver parenchymal cell (PC) is taurine. 19-23 These osmolytes not only serve to maintain homeostasis of cell volume, but regulate nonparenchymal cell function, e.g., phagocytosis, 24 tumor necrosis factor ␣ release, 25 and eicosanoid production. 19,26 Recently, a hepatoprotective effect of betaine and taurine in ischemia-reoxygenation injury in the perfused rat liver was shown. 27 Little is known about nonosmotic regulation of hepatic osmolytes. We therefore studied the interaction between hepatic nerves, cell hydration, and osmolyte status in the intact perfused rat liver and isolated liver PC and nonparenchymal cells. The results show that the osmolytes, taurine and inositol, can be released from the liver upon electrical nerve stimulation, and that this is caused by ␣-adrenergic mobilization of taurine from hepatic PC and inositol from hepatic stellate cells (HSC), whereas Kupffer cells (KC) and sinusoidal endothelial cells (SEC) do not contain ␣-adrenoceptors that are linked to Ca 2ϩ mobilization. MATERIALS AND METHODS Liver Perfusion Livers from male Wistar rats (160-230 g), who were fed a standard diet (Altromin, Lage, Germany), were perfused in situ in an open nonrecirculating manner as described previously. 28 The perfusion medium was bicarbonate-buffered Krebs-Henseleit saline plus lactate (2.1 mmol/L) and pyruvate (0.3 mmol/L), gassed with carbogen (O 2 /CO 2 : 19:1, vol/vol). Perfusate flow was 3.5 to 4.5 mL/min/g liver. After dissolution of the compounds in Krebs-Henseleit buffer (KHB), additions were made by use of micropumps (20 µL/min). In the case of 4,4Ј-di-isothiocyanatostilbene-2,2Ј
Biological Chemistry, 2013
We studied the downregulation of hepatobiliary transport systems and the effect of pharmacologica... more We studied the downregulation of hepatobiliary transport systems and the effect of pharmacological heme oxygenase-1 (HO-1) preinduction by Hemoglobin-Glutamer 200 (HbG200) in cold ischemia-reperfused rat liver (I/R). Cold I/R reduced bile flow in the reperfusion period from 3.10±0.10 ml/3 h to 0.54±0.20 ml/3 h…
Archives of Biochemistry and Biophysics, 2007
Apoptosis is characterized by cell shrinkage, nuclear condensation, DNA-fragmentation and apoptot... more Apoptosis is characterized by cell shrinkage, nuclear condensation, DNA-fragmentation and apoptotic body formation. Compatible organic osmolytes, e.g. taurine, modulate the cellular response to anisotonicity and may protect from apoptosis. Taurine transporter knockout mice (tautÀ/À mice) show strongly decreased taurine levels in a variety of tissues. They develop clinically important age-dependent diseases and some of them are characterized by apoptosis. Increased photoreceptor apoptosis leads to blindness of tautÀ/À mice at an early age. The taurine transporter may not be essential for the differentiation of photoreceptor cells, but many mature cells do not survive without an intact taurine transporter. The olfactory epithelium of tautÀ/À mice also exhibits structural and functional abnormalities. When compared with wild-types, tautÀ/À mice have a significantly higher proliferative activity of immature olfactory receptor neurons and an increased number of apoptotic cells. This is accompanied by electrophysiological findings indicating a reduced olfactory sensitivity. Furthermore, tautÀ/À and taut+/À mice develop moderate unspecific hepatitis and liver fibrosis beyond 1 year of age where hepatocyte apoptosis and activation of the CD95 system are pronounced.
Molecular aspects of medicine, 2004
Deutsches Aerzteblatt Online, Mar 29, 2019
An 87-year-old woman came to our emergency room complaining of diffuse abdominal pain. Laboratory... more An 87-year-old woman came to our emergency room complaining of diffuse abdominal pain. Laboratory testing revealed microcytic anemia (hemoglobin 5.9 mmol/L) with normal leukocyte and platelet counts, as well as a high C-reactive protein concentration (48.4 mg/L) and elevation of the cholestasis parameters alkaline phosphatase (12.32 µmol/L/s) and gamma-glutamyltransferase (33.03 µmol/L/s), with normal bilirubin and transaminase values. Abdominal ultrasonography revealed intra-and extrahepatic cholestasis with a markedly enlarged gall bladder containing large concretions. Computed tomography then yielded the finding illustrated at left, a siphon-like, hydropic, stone-filled gall bladder extending into the pelvis, with a tortuous and enlarged cystic duct and a prepapillary concretion in the common hepatic duct (arrow). The latter was then removed via endoscopic retrograde cholangiopancreatography. Histological examination of the prominent papilla revealed a florid, longstanding erosive papillitis, most likely due to recurrent outflow of concretions. After removal of the concretion and insertion of a stent, the biliary pathways were promptly unblocked and the cholestasis parameters reverted to normal. Elective cholecystectomy was recommended.
Hepatology, 1998
The effect of endothelin (ET) 1 on intracellular Ca2+ transients in cultured rat hepatic stellate... more The effect of endothelin (ET) 1 on intracellular Ca2+ transients in cultured rat hepatic stellate cells (HSCs) during transformation was studied by use of single-cell fluorescence. Regardless of the duration of HSC culture, ET-1 caused a BQ-123-sensitive but IRL-1038-insensitive elevation of [Ca2+]i, indicating the involvement of ETA but not ETB receptors. HSCs in early culture ("quiescent HSCs") were mildly responsive to ET-1: the ET-1 concentration required to obtain a [Ca2+]i transient in 50% of the cells (RC50) was 7 nmol/L, and all cells responded to ET-1 concentrations above 40 nmol/L. With culture time, -smooth muscle actin (-SMA) expression increased, as did the ET-1 sensitivity of cells, resulting in a shift of the RC50 value from 7 nmol/L to 13 pmol/L within 8 days. Independent of the duration of culture, ET-1 sensitivity was higher in -SMA-expressing cells. On the other hand, sensitivity of HSCs to produce a [Ca2+]i response to extracellular uridin 5'-triphosphate (UTP) or phenylephrine did not change during the activation process. There was no difference between quiescent and activated HSCs with respect to the sharing of intracellular Ca2+ stores, which could be mobilized by ET-1, UTP, and phenylephrine, respectively. The data suggest three conclusions. (1) A marked increase in ET-1 sensitivity of HSCs during the activation process suggests a potentiation of autocrine/paracrine stimulation. (2) HSCs are susceptible to -adrenergic and purinergic stimulation, but sensitivity to phenylephrine and UTP is not affected during the transformation process. (3) The ET-1-mobilizable Ca2+ store is contained in and is smaller than the Ca2+ pool, which is mobilized by phenylephrine or UTP.
Scientific reports, 2016
The calcium-activated potassium channel KCa3.1 controls different cellular processes such as prol... more The calcium-activated potassium channel KCa3.1 controls different cellular processes such as proliferation and volume homeostasis. We investigated the role of KCa3.1 in experimental and human liver fibrosis. KCa3.1 gene expression was investigated in healthy and injured human and rodent liver. Effect of genetic depletion and pharmacological inhibition of KCa3.1 was evaluated in mice during carbon tetrachloride induced hepatic fibrogenesis. Transcription, protein expression and localisation of KCa3.1 was analysed by reverse transcription polymerase chain reaction, Western blot and immunohistochemistry. Hemodynamic effects of KCa3.1 inhibition were investigated in bile duct-ligated and carbon tetrachloride intoxicated rats. In vitro experiments were performed in rat hepatic stellate cells and hepatocytes. KCa3.1 expression was increased in rodent and human liver fibrosis and was predominantly observed in the hepatocytes. Inhibition of KCa3.1 aggravated liver fibrosis during carbon tet...
Biological Chemistry, Mar 1, 2007
Hydrophobic bile salts activate NADPH oxidase through a ceramide- and PKCzeta-dependent pathway a... more Hydrophobic bile salts activate NADPH oxidase through a ceramide- and PKCzeta-dependent pathway as an important upstream event of bile salt-induced hepatocyte apoptosis. The mechanisms underlying bile salt-induced ceramide formation have remained unclear to date and thus were studied in rat hepatocytes. Proapoptotic bile salts, such as taurolithocholylsulfate (TLCS), lowered the apparent pHves within seconds from 6.0 to 5.6 in an FITC-dextran-accessible endosomal compartment that also contains acidic sphingomyelinase. Simultaneously, a rapid decrease in N-(ethoxycarbonylmethyl)-6-methoxyquinolinium bromide (MQAE) fluorescence was observed, suggestive of an increase in cytosolic [Cl-], which is known to activate vacuolar-type H+-ATPase. No vesicular acidification or increase in cytosolic [Cl-] was found in response to the non-apoptotic bile salt taurocholate or the anti-apoptotic bile salt tauroursodesoxycholate. Inhibition of TLCS-induced endosomal acidification by bafilomycin or 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid largely abolished the TLCS-induced ceramide-formation and downstream ceramide-dependent processes, such as p47phox-serine phosphorylation, NADPH oxidase activation, CD95 activation and apoptosis. These responses were also abolished after knockdown of acidic sphingomyelinase in rat hepatocytes. In conclusion, hydrophobic, proapoptotic bile salts stimulate ceramide formation through chloride-dependent acidification of endosomes, with subsequent activation of acidic sphingomyelinase. Our data suggest that changes in ion homeostasis underlie the stimulation of ceramide formation in response to hydrophobic bile acids as an important upstream event of bile salt-induced apoptosis.
Pancreas, Jun 30, 2003
Proliferation and matrix synthesis of activated pancreatic stellate cells (PSCs) participate in t... more Proliferation and matrix synthesis of activated pancreatic stellate cells (PSCs) participate in the development of chronic pancreatitis. Besides other substances, endothelin-1 (ET-1) may influence the activation process of PSCs. Until now, ET-1 has not been studied in this particular cell type. To characterize PSCs in rat pancreas with respect to expression of ET(A)-receptors, production of ET-1, and physiological effects induced by ET-1 during PSC activation. Immunocytochemical and ELISA techniques and cDNA microarray analysis were used. Physiologic effects were characterized by single cell measurements of free cytosolic Ca2+-concentration and of PSC contractility on collagen lattices. Activation of PSCs in vitro, as assessed by alpha-smooth muscle actin expression, was accompanied by the de novo expression of ET(A)-receptors and synthesis of ET-1 mRNA and protein. Cytosolic Ca2+-concentration was increased upon ET-1 stimulation in activated but not in quiescent PSCs. Contractility of activated PSCs was significantly reduced by the selective ET(A)-receptor antagonist BQ123 but not by the ET(B)-receptor antagonist IRL-1038. The results suggest that ET-1 may act as a paracrine and autocrine factor for activated PSCs and may mediate contractions of activated, but not quiescent, PSCs.
![Research paper thumbnail of [289] Hydrophobic Bile Salts Activate Nadph Oxidase Through Endosomal Acidification](https://attachments.academia-assets.com/47584339/thumbnails/1.jpg)
](J Hepatol, 2007
04A. MOLECULAR AND CELLULAR BIOLOGY -A) CELL CYCLE CONTROL/APOPTOSIS s115 liver interface was obs... more 04A. MOLECULAR AND CELLULAR BIOLOGY -A) CELL CYCLE CONTROL/APOPTOSIS s115 liver interface was observed in HCC-rats. GST-P expression, a marker of preneoplasic and neoplasic cells, was increased in rats with hepatocarcinogenesis. HCC induced a significant reduction on the expression of pro-apoptotic p-2 1 and caspase-3 proteins (-63% and -56% respectively) and on the release of cytochrome c (-50%). Moreover, expression of anti-apoptotic protein Bcl-2 in HCC-rats was increased. No changes were observed on caspase-8 expression. All those changes were inhibited by the TNP-470 treatment. Conclusions: In OUT animal in vivo model, treatment with TNP-470 is able to reduce HCC development. This effect seems to be related, at least in part, to an induction of the intrinsic apoptosis pathway (mitochondriarelated). TNP-470 could be an interesting candidate to the chemotherapeutic arsenal for HCC treatment. Project supported by the Junta de Castilla y Leon, Spain.
Gastroenterology, Jan 5, 2002
Background & Aims: Prevention of bile acid-induced apoptosis is of therapeutic interest and requi... more Background & Aims: Prevention of bile acid-induced apoptosis is of therapeutic interest and requires the understanding of underlying mechanisms. Methods: The effect of tauroursodeoxycholate (TUDC) on taurolithocholic acid-3 sulfate (TLCS)-induced apoptosis was studied in cultured rat hepatocytes. Results: TLCS induced activation of caspases 8, 9, and 3 and hepatocyte apoptosis. These effects were abolished by TUDC in a PI 3-kinase-/ protein kinase B (PKB)-, p38 MAPK-, and extracellular signal-regulated kinase-2 (Erk-2)-independent manner. These protein kinases were activated by both TLCS and TUDC, however, with different kinetics. TLCS, but not TUDC, led to a sustained activation of c-Jun N-terminal kinase (JNK) and CD95 trafficking to the plasma membrane; both TLCS effects were prevented by TUDC. Inhibition of JNK1 or protein kinase C prevented TLCS-induced CD95 membrane trafficking and blunted the apoptotic response. The apoptotic potency of other bile acids paralleled their ability to induce sustained JNK activation. Conclusions: Protection by TUDC against TLCS-induced apoptosis starts upstream of caspase 8 activation and is independent of a PI 3-kinase-dependent survival pathway. JNK activation may be important for bile acid-induced apoptosis by triggering ligand-independent CD95 surface trafficking and activation of apoptosis.
Z Gastroenterol, 2009
ABSTRACT
Clinical Hemorheology and Microcirculation, 2019
Colon cancer cells cultured under hyperosmotic conditions as in vitro model to investigate dehydr... more Colon cancer cells cultured under hyperosmotic conditions as in vitro model to investigate dehydration effects on cancer drug susceptibility
Insulin is known to induce hepatocyte swelling, which triggers via integrins and c-Src kinase an ... more Insulin is known to induce hepatocyte swelling, which triggers via integrins and c-Src kinase an activation of the epidermal growth factor receptor (EGFR) and subsequent cell proliferation (1). Free fatty acids (FFAs) are known to induce lipoapoptosis in liver cells in a c-Jun-NH2terminal kinase (JNK)-dependent, but death receptor-independent way (2). As nonalcoholic steatohepatitis (NASH) is associated with hyperinsulinemia and increased FFAblood levels, the interplay between insulin and FFA was studied with regard to hepatocyte proliferation and apoptosis in isolated rat and mouse hepatocytes. Saturated long chain FFAs induced apoptosis and JNK activation in primary rat hepatocytes, but did not activate the CD95 (Fas, APO-1) system, whereas insulin triggered EGFR activation and hepatocyte proliferation. Coadministration of insulin and FFAs, however, abolished hepatocyte proliferation and triggered CD95-dependent apoptosis due to a JNK-dependent association of the activated EGFR wi...
Journal of Hepatology, 2007
Journal of Hepatology, 2003
Journal of Hepatology, 1998
Hepatology, 1999
The effects of perivascular nerve stimulation and phenylephrine on osmolyte release were studied ... more The effects of perivascular nerve stimulation and phenylephrine on osmolyte release were studied in the intact perfused rat liver and isolated liver parenchymal cells (PC) and nonparenchymal cells. In the perfused liver, electrical stimulation of perivascular nerves (20 Hz/2 ms/20 V) led to a phentolamine-sensitive increase of cell hydration by 6.5% ؎ 1.2% (n ؍ 3) and a transient phentolaminesensitive stimulation of taurine and inositol, but not betaine, release. These nerve effects were mimicked by phenylephrine, but not prostaglandin F 2␣ , and were not affected by sodium nitroprusside (SNP) or ibuprofen. Nerve stimulationinduced taurine, but not inositol, release was inhibited by 4,4Ј-di-isothiocyanatostilbene-2,2Ј-disulphonic acid (DIDS) (50 mol/L). Single-cell fluorescence studies with isolated liver PC, Kupffer cells (KC), sinusoidal endothelial cells (SEC), and hepatic stellate cells (HSC) revealed that phenylephrine induced an increase in cytosolic free Ca 2؉ only in PC and HSC, but not in KC and SEC, whereas extracellular uridine triphosphate (UTP) produced Ca 2؉ transients/ oscillations in all liver cell types studied. Phenylephrine had no effect on osmolyte release from isolated KC and SEC, but increased taurine (but not inositol) release from PC and inositol (but not taurine) efflux from HSC. The data suggest that: 1) liver cell hydration and-consecutivelyosmolyte content are modulated by hepatic nerves via an ␣-adrenergic mechanism, which does not involve eicosanoids or hemodynamic changes; 2) that PC and HSC are the primary targets for nerve-dependent ␣-adrenergic activation, whereas 3) KC and SEC probably do not express ␣-adrenoceptors coupled to Ca 2؉ mobilization or osmolyte efflux. (HEPATOLOGY 1999;29:195-204.) In rat liver, many metabolic processes such as glycogen metabolism, urea and glutamine formation, bile excretion, ketogenesis, oxygen consumption, transferrin biosynthesis/ excretion, and cellular ion balance are under control of the nervous system 1-9 (reviewed in Shimazu 10 and Jungermann 11). These nerve effects are largely mediated by ␣-adrenergic mechanisms, but also involve secondary effects of eicosanoids, which are formed in response to nerve stimulation and play a role in the intercellular communication in the liver acinus. 11-13 In the rat liver, the propagation of the neural signal requires intact intercellular gap junctions. 14,15 Another determinant of metabolic liver function is the hydration state of liver cells and the availability of organic osmolytes for the different hepatocyte populations (reviewed in Häussinger 16-18). These organic osmolytes, such as taurine, betaine, and inositol, are accumulated within or released from the cells in response to osmotic stress. Whereas taurine, betaine, and inositol are important osmolytes in nonparenchymal liver cells, the major osmolyte of the liver parenchymal cell (PC) is taurine. 19-23 These osmolytes not only serve to maintain homeostasis of cell volume, but regulate nonparenchymal cell function, e.g., phagocytosis, 24 tumor necrosis factor ␣ release, 25 and eicosanoid production. 19,26 Recently, a hepatoprotective effect of betaine and taurine in ischemia-reoxygenation injury in the perfused rat liver was shown. 27 Little is known about nonosmotic regulation of hepatic osmolytes. We therefore studied the interaction between hepatic nerves, cell hydration, and osmolyte status in the intact perfused rat liver and isolated liver PC and nonparenchymal cells. The results show that the osmolytes, taurine and inositol, can be released from the liver upon electrical nerve stimulation, and that this is caused by ␣-adrenergic mobilization of taurine from hepatic PC and inositol from hepatic stellate cells (HSC), whereas Kupffer cells (KC) and sinusoidal endothelial cells (SEC) do not contain ␣-adrenoceptors that are linked to Ca 2ϩ mobilization. MATERIALS AND METHODS Liver Perfusion Livers from male Wistar rats (160-230 g), who were fed a standard diet (Altromin, Lage, Germany), were perfused in situ in an open nonrecirculating manner as described previously. 28 The perfusion medium was bicarbonate-buffered Krebs-Henseleit saline plus lactate (2.1 mmol/L) and pyruvate (0.3 mmol/L), gassed with carbogen (O 2 /CO 2 : 19:1, vol/vol). Perfusate flow was 3.5 to 4.5 mL/min/g liver. After dissolution of the compounds in Krebs-Henseleit buffer (KHB), additions were made by use of micropumps (20 µL/min). In the case of 4,4Ј-di-isothiocyanatostilbene-2,2Ј
Biological Chemistry, 2013
We studied the downregulation of hepatobiliary transport systems and the effect of pharmacologica... more We studied the downregulation of hepatobiliary transport systems and the effect of pharmacological heme oxygenase-1 (HO-1) preinduction by Hemoglobin-Glutamer 200 (HbG200) in cold ischemia-reperfused rat liver (I/R). Cold I/R reduced bile flow in the reperfusion period from 3.10±0.10 ml/3 h to 0.54±0.20 ml/3 h…
Archives of Biochemistry and Biophysics, 2007
Apoptosis is characterized by cell shrinkage, nuclear condensation, DNA-fragmentation and apoptot... more Apoptosis is characterized by cell shrinkage, nuclear condensation, DNA-fragmentation and apoptotic body formation. Compatible organic osmolytes, e.g. taurine, modulate the cellular response to anisotonicity and may protect from apoptosis. Taurine transporter knockout mice (tautÀ/À mice) show strongly decreased taurine levels in a variety of tissues. They develop clinically important age-dependent diseases and some of them are characterized by apoptosis. Increased photoreceptor apoptosis leads to blindness of tautÀ/À mice at an early age. The taurine transporter may not be essential for the differentiation of photoreceptor cells, but many mature cells do not survive without an intact taurine transporter. The olfactory epithelium of tautÀ/À mice also exhibits structural and functional abnormalities. When compared with wild-types, tautÀ/À mice have a significantly higher proliferative activity of immature olfactory receptor neurons and an increased number of apoptotic cells. This is accompanied by electrophysiological findings indicating a reduced olfactory sensitivity. Furthermore, tautÀ/À and taut+/À mice develop moderate unspecific hepatitis and liver fibrosis beyond 1 year of age where hepatocyte apoptosis and activation of the CD95 system are pronounced.
Molecular aspects of medicine, 2004
Deutsches Aerzteblatt Online, Mar 29, 2019
An 87-year-old woman came to our emergency room complaining of diffuse abdominal pain. Laboratory... more An 87-year-old woman came to our emergency room complaining of diffuse abdominal pain. Laboratory testing revealed microcytic anemia (hemoglobin 5.9 mmol/L) with normal leukocyte and platelet counts, as well as a high C-reactive protein concentration (48.4 mg/L) and elevation of the cholestasis parameters alkaline phosphatase (12.32 µmol/L/s) and gamma-glutamyltransferase (33.03 µmol/L/s), with normal bilirubin and transaminase values. Abdominal ultrasonography revealed intra-and extrahepatic cholestasis with a markedly enlarged gall bladder containing large concretions. Computed tomography then yielded the finding illustrated at left, a siphon-like, hydropic, stone-filled gall bladder extending into the pelvis, with a tortuous and enlarged cystic duct and a prepapillary concretion in the common hepatic duct (arrow). The latter was then removed via endoscopic retrograde cholangiopancreatography. Histological examination of the prominent papilla revealed a florid, longstanding erosive papillitis, most likely due to recurrent outflow of concretions. After removal of the concretion and insertion of a stent, the biliary pathways were promptly unblocked and the cholestasis parameters reverted to normal. Elective cholecystectomy was recommended.
Hepatology, 1998
The effect of endothelin (ET) 1 on intracellular Ca2+ transients in cultured rat hepatic stellate... more The effect of endothelin (ET) 1 on intracellular Ca2+ transients in cultured rat hepatic stellate cells (HSCs) during transformation was studied by use of single-cell fluorescence. Regardless of the duration of HSC culture, ET-1 caused a BQ-123-sensitive but IRL-1038-insensitive elevation of [Ca2+]i, indicating the involvement of ETA but not ETB receptors. HSCs in early culture ("quiescent HSCs") were mildly responsive to ET-1: the ET-1 concentration required to obtain a [Ca2+]i transient in 50% of the cells (RC50) was 7 nmol/L, and all cells responded to ET-1 concentrations above 40 nmol/L. With culture time, -smooth muscle actin (-SMA) expression increased, as did the ET-1 sensitivity of cells, resulting in a shift of the RC50 value from 7 nmol/L to 13 pmol/L within 8 days. Independent of the duration of culture, ET-1 sensitivity was higher in -SMA-expressing cells. On the other hand, sensitivity of HSCs to produce a [Ca2+]i response to extracellular uridin 5'-triphosphate (UTP) or phenylephrine did not change during the activation process. There was no difference between quiescent and activated HSCs with respect to the sharing of intracellular Ca2+ stores, which could be mobilized by ET-1, UTP, and phenylephrine, respectively. The data suggest three conclusions. (1) A marked increase in ET-1 sensitivity of HSCs during the activation process suggests a potentiation of autocrine/paracrine stimulation. (2) HSCs are susceptible to -adrenergic and purinergic stimulation, but sensitivity to phenylephrine and UTP is not affected during the transformation process. (3) The ET-1-mobilizable Ca2+ store is contained in and is smaller than the Ca2+ pool, which is mobilized by phenylephrine or UTP.
Scientific reports, 2016
The calcium-activated potassium channel KCa3.1 controls different cellular processes such as prol... more The calcium-activated potassium channel KCa3.1 controls different cellular processes such as proliferation and volume homeostasis. We investigated the role of KCa3.1 in experimental and human liver fibrosis. KCa3.1 gene expression was investigated in healthy and injured human and rodent liver. Effect of genetic depletion and pharmacological inhibition of KCa3.1 was evaluated in mice during carbon tetrachloride induced hepatic fibrogenesis. Transcription, protein expression and localisation of KCa3.1 was analysed by reverse transcription polymerase chain reaction, Western blot and immunohistochemistry. Hemodynamic effects of KCa3.1 inhibition were investigated in bile duct-ligated and carbon tetrachloride intoxicated rats. In vitro experiments were performed in rat hepatic stellate cells and hepatocytes. KCa3.1 expression was increased in rodent and human liver fibrosis and was predominantly observed in the hepatocytes. Inhibition of KCa3.1 aggravated liver fibrosis during carbon tet...
Biological Chemistry, Mar 1, 2007
Hydrophobic bile salts activate NADPH oxidase through a ceramide- and PKCzeta-dependent pathway a... more Hydrophobic bile salts activate NADPH oxidase through a ceramide- and PKCzeta-dependent pathway as an important upstream event of bile salt-induced hepatocyte apoptosis. The mechanisms underlying bile salt-induced ceramide formation have remained unclear to date and thus were studied in rat hepatocytes. Proapoptotic bile salts, such as taurolithocholylsulfate (TLCS), lowered the apparent pHves within seconds from 6.0 to 5.6 in an FITC-dextran-accessible endosomal compartment that also contains acidic sphingomyelinase. Simultaneously, a rapid decrease in N-(ethoxycarbonylmethyl)-6-methoxyquinolinium bromide (MQAE) fluorescence was observed, suggestive of an increase in cytosolic [Cl-], which is known to activate vacuolar-type H+-ATPase. No vesicular acidification or increase in cytosolic [Cl-] was found in response to the non-apoptotic bile salt taurocholate or the anti-apoptotic bile salt tauroursodesoxycholate. Inhibition of TLCS-induced endosomal acidification by bafilomycin or 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid largely abolished the TLCS-induced ceramide-formation and downstream ceramide-dependent processes, such as p47phox-serine phosphorylation, NADPH oxidase activation, CD95 activation and apoptosis. These responses were also abolished after knockdown of acidic sphingomyelinase in rat hepatocytes. In conclusion, hydrophobic, proapoptotic bile salts stimulate ceramide formation through chloride-dependent acidification of endosomes, with subsequent activation of acidic sphingomyelinase. Our data suggest that changes in ion homeostasis underlie the stimulation of ceramide formation in response to hydrophobic bile acids as an important upstream event of bile salt-induced apoptosis.
Pancreas, Jun 30, 2003
Proliferation and matrix synthesis of activated pancreatic stellate cells (PSCs) participate in t... more Proliferation and matrix synthesis of activated pancreatic stellate cells (PSCs) participate in the development of chronic pancreatitis. Besides other substances, endothelin-1 (ET-1) may influence the activation process of PSCs. Until now, ET-1 has not been studied in this particular cell type. To characterize PSCs in rat pancreas with respect to expression of ET(A)-receptors, production of ET-1, and physiological effects induced by ET-1 during PSC activation. Immunocytochemical and ELISA techniques and cDNA microarray analysis were used. Physiologic effects were characterized by single cell measurements of free cytosolic Ca2+-concentration and of PSC contractility on collagen lattices. Activation of PSCs in vitro, as assessed by alpha-smooth muscle actin expression, was accompanied by the de novo expression of ET(A)-receptors and synthesis of ET-1 mRNA and protein. Cytosolic Ca2+-concentration was increased upon ET-1 stimulation in activated but not in quiescent PSCs. Contractility of activated PSCs was significantly reduced by the selective ET(A)-receptor antagonist BQ123 but not by the ET(B)-receptor antagonist IRL-1038. The results suggest that ET-1 may act as a paracrine and autocrine factor for activated PSCs and may mediate contractions of activated, but not quiescent, PSCs.
J Hepatol, 2007
04A. MOLECULAR AND CELLULAR BIOLOGY -A) CELL CYCLE CONTROL/APOPTOSIS s115 liver interface was obs... more 04A. MOLECULAR AND CELLULAR BIOLOGY -A) CELL CYCLE CONTROL/APOPTOSIS s115 liver interface was observed in HCC-rats. GST-P expression, a marker of preneoplasic and neoplasic cells, was increased in rats with hepatocarcinogenesis. HCC induced a significant reduction on the expression of pro-apoptotic p-2 1 and caspase-3 proteins (-63% and -56% respectively) and on the release of cytochrome c (-50%). Moreover, expression of anti-apoptotic protein Bcl-2 in HCC-rats was increased. No changes were observed on caspase-8 expression. All those changes were inhibited by the TNP-470 treatment. Conclusions: In OUT animal in vivo model, treatment with TNP-470 is able to reduce HCC development. This effect seems to be related, at least in part, to an induction of the intrinsic apoptosis pathway (mitochondriarelated). TNP-470 could be an interesting candidate to the chemotherapeutic arsenal for HCC treatment. Project supported by the Junta de Castilla y Leon, Spain.
Gastroenterology, Jan 5, 2002
Background & Aims: Prevention of bile acid-induced apoptosis is of therapeutic interest and requi... more Background & Aims: Prevention of bile acid-induced apoptosis is of therapeutic interest and requires the understanding of underlying mechanisms. Methods: The effect of tauroursodeoxycholate (TUDC) on taurolithocholic acid-3 sulfate (TLCS)-induced apoptosis was studied in cultured rat hepatocytes. Results: TLCS induced activation of caspases 8, 9, and 3 and hepatocyte apoptosis. These effects were abolished by TUDC in a PI 3-kinase-/ protein kinase B (PKB)-, p38 MAPK-, and extracellular signal-regulated kinase-2 (Erk-2)-independent manner. These protein kinases were activated by both TLCS and TUDC, however, with different kinetics. TLCS, but not TUDC, led to a sustained activation of c-Jun N-terminal kinase (JNK) and CD95 trafficking to the plasma membrane; both TLCS effects were prevented by TUDC. Inhibition of JNK1 or protein kinase C prevented TLCS-induced CD95 membrane trafficking and blunted the apoptotic response. The apoptotic potency of other bile acids paralleled their ability to induce sustained JNK activation. Conclusions: Protection by TUDC against TLCS-induced apoptosis starts upstream of caspase 8 activation and is independent of a PI 3-kinase-dependent survival pathway. JNK activation may be important for bile acid-induced apoptosis by triggering ligand-independent CD95 surface trafficking and activation of apoptosis.
Z Gastroenterol, 2009
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