Protein Synthesis In Hepatocytes Research Articles

Therapeutic benefit of oregano oil in the acute idiosyncratic hepatotoxicity induced by carbon tetrachloride in rats: Adverse effects of high dose of oreganum.

Toxicity caused by carbon tetrachloride (CCl4) can lead to serious liver injury. The aim of the study is to investigate the protective effects of oregano oil (Origanum minutiflorum extract oil) against CCl4-induced liver injury. Two doses of oregano oil were used in the experiment: a low dose (LD; 20 mg/kg) and a high dose (HD; 60 mg/kg) during 2 weeks. CCl4 caused severe liver damage, nucleolus destruction in hepatocytes and cytogenetic changes in the nucleus. Indirectly, CCl4 causes decreased protein synthesis and significantly high creatinine and urea values. Hematological disorders have been recorded, such as decreased RBC and hemoglobin concentration, increased WBC and deformability of the erythrocyte membrane. Both doses of oregano oil had protective effects. Improved protein synthesis and high globulins level, creatinine and urea were found in both groups. Cytogenetic changes in the nucleus of hepatocytes were reduced. A high dose of oregano oil had maximal protective effects for RBC, but a very weak effect on hemoglobin synthesis. Also, WBC and lymphocyte values were low. Origanum stimulates protein synthesis and recovery of hepatocytes after liver injury, reduces the deformability of the erythrocyte membrane. High doses of oregano oil decreased WBC and lymphocytes which may lead to a weakening of the immune response. However, high doses are more effective against severe platelet aggregation than low doses, suggesting an effective treatment against thrombocytosis.

Метаболические особенности и микрофлора молока при маститах у коров Амурской области

The effective management practices of dairy farming are inextricably linked with the production of high quality milk, while the mastitis is one of the causes of reductions in milk yields and quality. The aim of the work was to study the microbiological profile of milk, the sensitivity of isolated microorganisms to antibiotics and metabolism features of cows with mastitis in the Amur Oblast. The following microorganisms were identified in the milk samples from cows with mastitis: Staphylococcus epidermidis (34.69%); microbial associations: Streptococcus agalactiae + Escherichia coli (32.65%) and Staphylococcus saprophyticus + Streptococcus agalactiae + Escherichia coli (30.61%); Staphylococcus haemolyticus (2.05%). Microorganisms isolated from the milk of mastitis-affected cows were susceptible to the following antimicrobials: Escherichia coli to cefotaxime (28.00 ± 2.00 mm) and ceftriaxone (27.50 ± 0.35 mm); Staphylococcus epidermidis, Staphylococcus haemolyticus, Staphylococcus saprophyticus to cefotaxime (35.50 ± 0.18 mm) and amoxicillin (35.10 ± 0.35 mm); Streptococcus agalactiae to tetracycline (27.60 ± 1.17 mm) and gentamicin (26.40 ± 0.99 mm). Metabolic disorders were observed in cows with mastitis. The albumin-globulin ratio was reduced (0.41), which is typical for various inflammatory processes; and a low albumin levels (29.00 ± 0.89%) suggested a decreased protein synthesis in hepatocytes. A moderate increase in gamma globulins (47.60 ± 1.05%) was associated with stimulation of the phagocytic mononuclear system. Water and mineral metabolism disorders were confirmed by low levels of calcium (1.80 ± 0.03 mmol/L) and magnesium (0.70 ± 0.02 mmol/L), which is a sign of many pathological conditions, and is associated with heavy lactation. Calcium-phosphorus ratio was reduced (0.82). Hematological indicators suggested hypochromic anemia (hemoglobin level – 100.60 ± 1.28 g/L, globular value – 0.60 ± 0.01). The leukogram was indicative of lymphocytopenia (36.90 ± 2.60%) and neutrophilia (rod-shaped neutrophils – 1.80 ± 0.13%, segmented neutrophils – 51.80 ± 2.51%).

Secreted MUP1 that reduced under ER stress attenuates ER stress induced insulin resistance through suppressing protein synthesis in hepatocytes

Disturbed endoplasmic reticulum (ER) stress response driven by the excessive lipid accumulation in the liver is a characteristic feature in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). Restoring metabolic homeostasis by targeting ER stress is a potentially therapeutic strategy for NAFLD. Here we aim to identify novel proteins or pathways involved in regulating ER stress response and therapeutic targets for alleviating NAFLD. Proteomic and transcriptomic analysis demonstrated that major urinary proteins (MUPs) were significantly reduced in the livers from NAFLD mouse models. Then we confirmed that MUP1, the major secreted form of MUPs, was reduced at mRNA and protein expression levels in hepatocytes both in vivo and in vitro under ER stress. We further illustrated that MUP1 protein levels in the urine were reduced in mice with NAFLD, which was reversed by GLP-1 receptor agonist treatment. To study the relationship between ER stress and MUP1 biology, our analysis demonstrated that MUP1 was misfolded and trapped in the ER under ER stress in vivo. Interestingly, we discovered that recombinant MUP1 treatment in hepatocytes increased calcium efflux from the ER, which resulted in transient ER stress response, including reduced protein synthesis. These responses facilitated the alleviation of chemical induced ER stress in hepatocytes, which was suggested as “pre-adaptive ER stress”. Besides, recombinant MUP1 pretreatment also improved ER stress-induced insulin resistance in hepatocytes. Our findings revealed a novel and critical role of MUP1, and recombinant MUP1 or its potential derivates may serve as a promising therapeutic target for alleviating NAFLD.

Endotoxin-Stimulated Hepatic Stellate Cells Augment Acetaminophen-Induced Hepatocyte Injury

Acetaminophen (APAP)-induced liver injury is influenced by inflammatory Gram-negative bacterial endotoxin [lipopolysaccharide (LPS)], mechanisms of which are not completely understood. Because LPS-stimulated perisinusoidal hepatic stellate cells (HSCs) produce cytokines that affect survival of hepatocytes, this study investigated their role in APAP-induced liver injury. Fed (nonstarved) rats were administered 5 mg/kg LPS or phosphate-buffered saline (PBS) vehicle, followed by 200 mg/kg APAP or PBS an hour later, and euthanized at 6 hours. Control rats received PBS at both time points. Both LPS and APAP caused mild hepatocyte injury (apoptosis), as assessed by histopathology, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining, and caspase-3 activation. The liver injury was augmented in rats administered LPS + APAP, in association with increased nuclear translocation of interferon-regulatory factor-1 (IRF1). Invitro, APAP augmented LPS/HSC-conditioned medium-induced inhibition of DNA and protein synthesis, apoptosis, and nuclear IRF1 in hepatocytes. LPS-stimulated HSCs produced interferon-β (IFN-β), and LPS/HSC + APAP-induced hepatocyte apoptosis was inhibited by anti-IFN-β antibody. Finally, HSC-depleted mice produced significantly lower IFN-β and tumor necrosis factor-α, exhibited less oxidative stress, and were protected from excessive injury due to high APAP dose (600 mg/kg), as well as LPS (5 mg/kg overnight) followed by APAP. In co-culture with or without LPS, HSCs increased expression of proinflammatory cytokines by Kupffer cells. These results suggest that HSCs play a critical role in APAP-induced liver injury without or with LPS preconditioning, and it involves INF-β-IRF1 signaling.

Pituitary Somatotroph Adenoma-derived Exosomes: Characterization of Nonhormonal Actions.

ContextThe identification and biological actions of pituitary-derived exosomes remain elusive.ObjectiveThis work aimed to validate production of exosomes derived from human and rat pituitary and elucidate their actions.MethodsIsolated extracellular vesicles (EVs) were analyzed by Nanoparticle Tracking Analysis (NTA) and expressed exosomal markers detected by Western blot, using nonpituitary fibroblast FR and myoblast H9C2 cells as controls. Exosome inhibitor GW4869 was employed to detect attenuated EV release. Exosomal RNA contents were characterized by RNA sequencing. In vitro and in vivo hepatocyte signaling alterations responding to GH1-derived exosomes (GH1-exo) were delineated by mRNA sequencing. GH1-exo actions on protein synthesis, cAMP (3′,5′-cyclic adenosine 5′-monophosphate) response, cell motility, and metastases were assessed.ResultsNTA, exosomal marker detection, and GW4869 attenuated EV release, confirming the exosomal identity of pituitary EVs. Hydrocortisone increased exosome secretion in GH1 and GH3 cells, suggesting a stress-associated response. Exosomal RNA contents showed profiles distinct for pituitary cells, and rat primary hepatocytes exposed to GH1-exo exhibited transcriptomic alterations distinct from those elicited by growth hormone or prolactin. Intravenous GH1-exo injection into rats attenuated hepatic Eif2ak2 and Atf4 mRNA expression, both involved in cAMP responses and amino acid biosynthesis. GH1-exo suppressed protein synthesis and forskolin-induced cAMP levels in hepatocytes. GH1-exo–treated HCT116 cells showed dysregulated p53 and mitogen-activated protein kinase (MAPK) pathways and attenuated motility of malignant HCT116 cells, and decreased tumor metastases in nude mice harboring splenic HCT116 implants.ConclusionOur findings elucidate biological actions of somatotroph-derived exosomes and implicate exosomes as nonhormonal pituitary-derived messengers.

The Administration of Semax and HLDF-6 Peptides to Rats Regulates Protein Synthesis Rhythm in Hepatocytes and Corrects Senescent Disturbances

To clarify the organizing effect of Semax and HLDF-6 peptides on the kinetics of protein synthesis in hepatocytes, in addition to an in vitro study (Brodsky et al., 2019), the effects of these peptides in vivo have been studied. The circahoralian (ultradian) rhythm of protein synthesis, that is, a marker of the direct cell-to-cell communication, was investigated in rats of different ages. Peptides were injected intraperitoneally into young (2–3-month-old) or old (1.5–2-year-old) rats at a 50–100-µg/kg dose. Hepatocytes were isolated and sparse or dense cultures were established. In sparse cultures from young rats that received one or another peptide, the rhythm of protein synthesis was observed; in the cultures from rats of the same age that were injected with saline, no rhythm was found. In dense cultures of old rats after the action of the peptide, the amplitudes of the rhythm of protein synthesis did not differ from the rhythms observed in young rats; after saline injection, the rhythm amplitudes were twice as low. Injection of the peptide into adult rats that had previously received dopamine caused a protein synthesis rhythm characteristic for rats of this age; the administration of dopamine abolished the rhythm. The synchronizing effect of the peptides was maintained for at least 2 days after their single administration to the rat. The use of Semax or HLDF-6 is recommended to compensate for the disturbances of the kinetics of protein synthesis in humans in aging and pathology.

Threatening biomarkers in lupus pregnancy: Biochemistry and genetic challenges

Using genetic markers and miRs work strongly beside other sensitive biomarkers in lupus management during sensitive period of pregnancy. PubMed and Google Scholar databases were searched from 2000 to 2017 using the terms “lupus,” “lupus pregnancy,” “biomarkers,” “micro-RNA,” “polymorphisms,” “anti-phospholipid antibodies,” and “cluster differentiation markers.” Complement is a valuable biomarker in lupus pregnancy. However, the complement profile has ambiguous meaning because decreased levels of C3 and C4 reflect inflammation and because they are also prognostic biomarkers for abortion. Furthermore, increased C3 and C4 levels indicate hepatic protein synthesis in hepatocytes. Anti-phospholipid (APL) antibodies are present in 25% to 50% of lupus patients, and can lead to thrombotic and obstetric complications in some pregnancies and increase the risk of abortion, especially in a pregnant woman in the active phase of lupus. Several studies have associated APL with HELLP syndrome. However, other pregnancy complications have not been associated with APL. Autoantibodies against the major vault protein and anti-double strand DNA antibodies are valuable biomarkers in evaluating lupus activity. The expression pattern of micro-RNAs (miRs) differs in various diseases. Current studies have demonstrated the potential of miRs as diagnostic and prognostic biomarkers in various diseases; for example, the level of miR-126 is higher in lupus. Mir-223-3p and miR-451 are informative biomarkers in estimating disease activity. TWEAK, BAFF, and APOL1 genes, and their polymorphisms are informative in estimating disease activity, especially renal effects, and in monitoring higher-risk pregnant women. Further studies of these genes and their relevant polymorphisms are needed.

Metformin Inhibits Hepatic mTORC1 Signaling via Dose-Dependent Mechanisms Involving AMPK and the TSC Complex

Metformin is the most widely prescribed drug for the treatment of type 2 diabetes. However, knowledge ofthe full effects of metformin on biochemical pathways and processes in its primary target tissue, theliver, is limited. One established effect of metformin is to decrease cellular energy levels. The AMP-activated protein kinase (AMPK) and mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) are key regulators of metabolism that are respectively activated and inhibited in acute response to cellular energy depletion. Here we show that metformin robustly inhibits mTORC1 in mouse liver tissue and primary hepatocytes. Using mouse genetics, we find that at the lowest concentrations of metformin that inhibit hepatic mTORC1 signaling, this inhibition is dependent on AMPK and the tuberous sclerosis complex (TSC) protein complex (TSC complex). Finally, we show that metformin profoundly inhibits hepatocyte protein synthesis in a manner that is largely dependent on its ability to suppress mTORC1 signaling.

Pirimidine derivatives as hepatoprotective agents.

Research and development of effective hepatoprotective medicines is one of the priority areas of research in Russia. Literature data shows that active research and development of hepatoprotectors is carried out both in Russian and other countries [1-6]. Pirimidines are used as hepatoprotective medicines stimulating protein synthesis and reparation of hepatocytes in toxical and infectious liver disorders [7]. In our previous work ee have shown hepatoprotective properties of pyrimidine derivative, named Xymedon [8]. This research, funded by the Russian Science Foundation, is aimed at identifying the most effective hepatoprotectors among pirimidine derivatives. To test hepatoprotective properties of one of the new Xymedon (Xym) derivative - L-ascorbate 1-(2-hydroxyethyl)-4,6-dimethyl-1,2-dihydro-pirimidine-2-one (Asc-Xym) on the toxic liver damage model induce by carbon tetrachloride (CTC, CCl4). The toxic liver damage in rats was modeled by subcutaneous injection of CTC (CCl4) in vegetable oil (mixed at 1:1 ratio) at a dose of 2 ml per kg. The experiments were carried out under two schemes: 1) oral administration of Xym or Asc-Xym preparations by gavage at the doses of 10 and 20 mg/kg followed by subcutaneous injection of CTC 1 hour after pyrimidine oral administration and continued for 3-4 days; - this was the design of preventive pyrimidine use, 2) liver damage modeling by CTC subcutaneous injections for 3 days followed by oral administration of Xym, Asc-Xym or Thiotriazolin (Thi) preparations at the doses of 20 mg/kg for 5 days; - this was the design of therapeutic scheme. The rats of control groups were injected with CTC according to the same schemes, but did not get any preparations. We looked at some biochemical parameters of blood serum: alanine aminotran-sferase (AlAT), aspartate aminotransferase (AsAT), their ratio (de Rytis coefficient), and the total protein level as the markers of toxic liver damage. We performed statistical data analysis by rank nonparametric Mann-Whitney U-criterion for comparison of two independent groups. We evaluated pathomorphologic characteristics of liver damage on the histological slices colored with hematoxylin and eosin. Carbon tetrachloride (CTC) caused profound changes in the studied biochemical parameters of rats' blood serum. The AlAT activity level in the serum of control animals in the preventive scheme was 116,23 (the median) with the lower quartile and the upper quartile of 76,96 and 211,71 U/l respectively; the AsAT level was 230,08/201,49-290,03 U/l; this was the increase in comparison with the reference values. De Rytis coefficient was 1,76 /1,47-2,67. This was the decrease in comparison with the reference values of intact group (36,37/28,18-43,3 U/l; 132,95 /118,24-164,00 U/l and 4,26/3,03-5,23 respectively). The differences were statistically significant at P < 0,001. In the experimental groups the changes of the biochemical parameters with respect to the reference values were less marked than in Control. The AlAT level was 89,86/87,06-165,15; 103,23/38,19-270,87 U/l; 80,28/6,12-141,82 and 100,33/62,24-144,64 U/l in the groups of rats treated with Xym at the doses of 10 and 20 mg/kg or Asc-Xym at the doses of 10 and 20 mg/kg respectively. Similarly, in the same groups the AsAT level was 211,19/170,20-250,16; 193,61 /181,57-274,69 U/l; 190,91 /65,21-198,65 and 173,25/135,50-210,70 U/l respectively. The differences of the AsAT level were statistically significant at P < 0,05 in comparison with Control in the both groups treated with Asc-Xym.Nnearly 2 times increase of the AlAT level (67,60/1,22-94,60 U/l) (P = 0,00002) was shown in comparison with the reference values in the rats of Control group in the therapeutic scheme. However the AsAT level (163,80/130,1-178,8 U/l) was only slightly higher than reference values. De Rytis coefficient (2,07/1,78-3,48) was significantly lower than the reference values (P = 0,001). The total protein level (59,36/55,17-60,10 g/l) was lower than the reference values (65,06/62,06-68,98 g/l) by 8,4%. The differences of biochemical parameters as compared with the reference values in rats of experimental groups treated with Xym, Thi and Asc-Xym at the doses 20 mg/kg were less than those in the Control groups. They were: AlAT 52,49/44,64-62,30 and 61,42/53,20-96,66 U/l, AsAT 105,00/94,7-142,3 and 235,35/111,7-335,6 U/l, de Rytis coefficient 2,09/1,87-2,28 and 3,24/1,86-4,53, total protein 63,10/62,46-64,27 and 62,46/58,70-64,43 g/l respectively in the groups treated with Xym and Thi. The values of the studied biochemical parameters AlAT (39,04/32,46-44,24 U/l), AsAT (111,9/105,27-155 U/l), de Rytis coefficient (2,87/2,72-3,30), total protein (62,89/61,46-68,14 g/l) of the rats, treated with Asc-Xym, were the most close to the reference values in comparison with other experimental groups.The analysis of histological slices revealed large areas of steatosis and necrosis of hepatocytes in Control groups in both schemes. These were less pronounced in experimental groups than in Control groups and particularly in rats, treated with Asc-Xym. Hepatoprtotective properties of the new compound L-ascorbate 1-(2-hydroxyethyl)-4,6-dimethyl-1,2-dihydropirimidine-2-one were established. The hepatoprotective efficacy of the compound is higher than that of Xymedon and Thiotriazolin.

Administration of dopamine to rats disorganizes the rhythm of protein synthesis in hepatocytes.

Dopamine was injected intravenously (9 μg/kg) or intraperitoneally (15 μg/kg) to Wistar rats (3-4 months, 300-400 g). Hepatocytes were isolated 40 min after dopamine injection. Dense cultures were maintained on collagen-coated glasses. By the 5th hour, the circaholarian rhythm of protein synthesis in hepatocytes cultures was absent in the dopamine group, but was present in cultures from animals receiving physiological saline (NaCl). The rhythm-disorganizing effect of dopamine was reversible. The rhythm was observed in cultures of hepatocytes isolated 1 day after dopamine treatment. The effect of dopamine was abolished by melatonin. The protein synthesis rhythm was revealed in 5-h cultures of hepatocytes from rats receiving melatonin (32 ng/kg) 40 min after intraperitoneal injection of dopamine. The results of our in vitro experiments with addition of dopamine into the medium of cultured hepatocytes [1] suggest that dopamine in vivo produces a direct effect on liver cells. The observed changes are discussed taking into account the biochemical mechanisms for a direct cell-cell interaction and previously unknown properties of catecholamines.

Effect of Protein Synthesis Rhythm-Organizing Signal Persists for a Day after Single Administration of Melatonin to Rat

Melatonin administered to rat intraperitoneally organizes ultradian rhythm of protein synthesis in hepatocytes that persists for 1 day after exposure to the synchronizing signal. Hepatocytes were isolated 1 day after melatonin administration and cultured on coverslips in a serum-free medium. In 24 h in culture, the kinetics of protein synthesis was analyzed. In our previous experiments, we detected a rhythm in cells isolated in 1.5 h, but not in 3 days after melatonin administration to the rat. We have found that synchronization of oscillations of the protein synthesis intensity in vivo persists over 1 day after rat exposure to melatonin. Phenylephrine, an efficient synchronizer of protein synthesis in vitro, does not organize the rhythm in vivo.

Hepatoprotective effect of silymarin

The use of medicinal plants in treating illnesses has been reported since ancestral times. In the case of hepatic diseases, several species such as Silybum marianum, Phyllanthus niruri, and Panus giganteus (Berk.) have been shown to ameliorate hepatic lesions. Silymarin is a natural compound derived from the species Silybum marianum, which is commonly known as Milk thistle. This plant contains at least seven flavoligands and the flavonoid taxifolin. The hepatoprotective and antioxidant activity of silymarin is caused by its ability to inhibit the free radicals that are produced from the metabolism of toxic substances such as ethanol, acetaminophen, and carbon tetrachloride. The generation of free radicals is known to damage cellular membranes and cause lipoperoxidation. Silymarin enhances hepatic glutathione and may contribute to the antioxidant defense of the liver. It has also been shown that silymarin increases protein synthesis in hepatocytes by stimulating RNA polymerase I activity. A previous study on humans reported that silymarin treatment caused a slight increase in the survival of patients with cirrhotic alcoholism compared with untreated controls.

How to use C-reactive protein in acute coronary care

C-reactive protein is an acute phase protein and an established marker for detection, risk stratification, and monitoring of infections and inflammatory and necrotic processes. Because C-reactive protein is sensitive but not specific, its values must be interpreted in the clinical context. In patients with acute myocardial infarction (AMI), C-reactive protein increases within 4–6 h of symptoms, peaks 2–4 days later, and returns to baseline after 7–10 days.1 C-reactive protein has gained interest recently as a marker for risk stratification in acute coronary syndrome (ACS) when measured by high-sensitivity C-reactive protein assays. These assays have greater analytical sensitivity and reliably measure C-reactive protein concentrations within the reference range with low imprecision (5–10%).2 Because of evidence that atherosclerosis is an inflammatory disease, high-sensitivity C-reactive protein can be used as a biomarker of risk in primary prevention and in patients with known cardiovascular disease.3 The aim of this review is to evaluate the use of C-reactive protein in patients with acute coronary disease. C-reactive protein is a non-specific first-line host defence mechanism.4 With stimulation by cytokines (e.g. interleukins and tumour necrosis factor-alpha), C-reactive protein synthesis in hepatocytes occurs within 4–6 h. Concentrations can rise 1000-fold or more over 24–48 h. C-reactive protein has been detected in atherosclerotic plaques; its possible role in atherosclerogenesis is summarized in Figure 1 , but is still a matter of debate.5 Genetic variants account for 35–40% of the variability in high-sensitivity C-reactive protein.6 Figure 1 Possible pathophysiological effects of C-reactive protein in atherosclerosis. Aggregated C-reactive protein selectively binds LDL and VLDL in serum, thereby potentially participating in the mechanisms involved in plaque formation and destabilization, and shows some of the key properties of antibodies and may contribute to immune responses by activation of antigen presenting cells. Procoagulant effects have been reported in vitro as …

Assessment of energetic costs of AhR activation by β-naphthoflavone in rainbow trout (Oncorhynchus mykiss) hepatocytes using metabolic flux analysis

Exposure to environmental contaminants such as activators of the aryl hydrocarbon receptor (AhR) leads to the induction of defense and detoxification mechanisms. While these mechanisms allow organisms to metabolize and excrete at least some of these environmental contaminants, it has been proposed that these mechanisms lead to significant energetic challenges. This study tests the hypothesis that activation of the AhR by the model agonist β-naphthoflavone (βNF) results in increased energetic costs in rainbow trout (Oncorhynchus mykiss) hepatocytes. To address this hypothesis, we employed traditional biochemical approaches to examine energy allocation and metabolism including the adenylate energy charge (AEC), protein synthesis rates, Na+/K+-ATPase activity, and enzyme activities. Moreover, we have used for the first time in a fish cell preparation, metabolic flux analysis (MFA) an in silico approach for the estimation of intracellular metabolic fluxes. Exposure of trout hepatocytes to 1μM βNF for 48h did not alter hepatocyte AEC, protein synthesis, or Na+/K+-ATPase activity but did lead to sparing of glycogen reserves and changes in activities of alanine aminotransferase and citrate synthase suggesting altered metabolism. Conversely, MFA did not identify altered metabolic fluxes, although we do show that the dynamic metabolism of isolated trout hepatocytes poses a significant challenge for this type of approach which should be considered in future studies.

Proteostasis: a new therapeutic paradigm for pulmonary disease.

Among lung pathologies, α1AT, chronic obstructive pulmonary disease (COPD), emphysema, and asthma are diseases triggered by local environmental stress in the airway that we refer to herein collectively as airway stress diseases (ASDs). A deficiency of α-1-antitrypsin (α1AT) is an inherited genetic disorder that is a consequence of the misfolding of α1AT during protein synthesis in liver hepatocytes, reducing secretion to the plasma and delivery to the lung. Deficiency of α1AT in the lung triggers a similar pathological phenotype to other ASDs. Moreover, the loss of α1AT in the lung is a well-known environmental risk factor for COPD/emphysema. To date there are no effective therapeutic approaches to address ASDs, which reflects a general lack of understanding of their cellular basis. Herein, we propose that ASDs are disorders of proteostasis. That is, they are initiated and propagated by a common theme-a challenge to protein folding capacity maintained by the proteostasis network (PN) (see Balch et al., Science 2008;319:916-919). The PN is a network of chaperones and degradative components that generates and manages protein folding pathways responsible for normal human physiology. In ASD, we suggest that the PN system fails to respond to the increased burden of unfolded proteins due to genetic and environmental stresses, thus triggering pulmonary pathophysiology. We introduce the enabling concept of proteostasis regulators (PRs), small molecules that regulate signaling pathways that control the composition and activity of PN components, as a new and general approach for therapeutic management of ASDs.

Melatonin as the most effective organizer of the rhythm of protein synthesis in hepatocytes in vitro and in vivo

Recent data has extended a large array of melatonin functions by the discovery of melatonin's involvement in the organization and regulation of the rhythm of intracellular protein synthesis. An ultradian rhythm in total protein synthesis has been detected in primary hepatocyte cultures 5 min after addition of 1-5 nM melatonin to the medium. The melatonin effect was mediated via its receptors (as shown in experiments with luzindole), leading to the cell synchronization as well as the mean rate of protein synthesis rate being increased. The chain of processes synchronizing the oscillation of the rate protein synthesis throughout the hepatocyte population includes Ca²+ fluxes {experiments with BAPTA-AM [1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (acetomethyl ester)]}. Inhibition of protein kinase activity (experiments with H7) inhibited the synchronizing function of melatonin. Activation of protein kinase activity results in a shift of the protein synthesis oscillation; the effect was the same as melatonin added to the culture medium. In another series of experiments, after melatonin was intraperitoneally injected to rat (0.015-0.020 μg/kg), hepatocytes were isolated and cultures established. A synchronizing effect of melatonin in vivo was detected as early as in the estimates from the direct action of melatonin on cell cultures. In the cultures obtained from old rats provided with melatonin, the amplitude of protein synthesis rhythm was enhanced, i.e. cell-cell interactions were increased, as well as rate of the protein synthesis being enhanced.

Effect of Garcinia hydroxybiflavanonols on protein synthesis in primary cultured rat hepatocytes

Garcinia kola Heckel (Guttiferae) known as Aki-ilu (meaning bitter kola) is a large economic tree indigenous to the southern part of Nigeria. Its seeds have been of interest to researchers because of its use in the treatment of various disease conditions in Nigerian traditional medicine. The effect of the Garcinia hydroxybiflavanonols GB1 and GB2 on the rate of protein synthesis in primary cultured hepatocytes from rat livers was studied in vitro. This work provides further information on the mechanism of action of the liver active principles of G. kola nuts. A dose-dependent stimulatory effect of the drugs on the rate of protein synthesis in rat hepatocytes was found. Both GB1 and GB2 showed significant stimulatory effect on liver cell regeneration. These findings demonstrate that the reported antihepatotoxic activity of the Garcinia hydroxybiflavanonols could be explained, at least in part, by their stimulatory effect on the protein synthetic apparatus. GB1 increased the rate of protein synthesis about thrice as much as silibinin, a flavonolignan with proven antihepatotoxic activity, and suggests that this compound could be a potential novel antihepatotoxic agent.

Adipocyte‐derived basement membrane extract with biological activity: applications in hepatocyte functional augmentationin vitro

Natural and synthetic biomaterials utilized in tissue engineering applications require a dynamic interplay of complex macromolecular compositions of hydrated extracellular matrices (ECMs) and soluble growth factors. The challenges in utilizing synthetic ECMs is the effective control of temporal and spatial complexity of multiple signal presentation, as compared to natural ECMs that possess the inherent properties of biological recognition, including presentation of receptor-binding ligands, susceptibility to cell-triggered proteolytic degradation, and remodeling. We have developed a murine preadipocyte differentiation system for generating a natural basement membrane extract (Adipogel) comprising ECM proteins (collagen IV, laminin, hyaluronan, and fibronectin) and including relevant growth factors (hepatocyte growth factor, vascular endothelial growth factor, and leukemia inhibitory factor). We have shown the effective utilization of the growth factor-enriched extracellular matrix for enhanced albumin synthesis rate of primary hepatocyte cultures for a period of 10 d as compared to collagen sandwich cultures and comparable or higher function as compared to Matrigel cultures. We have also demonstrated comparable cytochrome P450 1A1 activity for the collagen-Adipogel condition to the collagen double-gel and Matrigel culture conditions. A metabolic analysis revealed that utilization of Adipogel in primary hepatocyte cultures increased serine, glycine, threonine, alanine, tyrosine, valine, methionine, lysine, isoleucine, leucine, phenylalanine, taurine, cysteine, and glucose uptake rates to enhance hepatocyte protein synthesis as compared to collagen double-gel cultures. The demonstrated synthesis, isolation, characterization, and application of Adipogel provide immense potential for tissue engineering and regenerative medicine applications.

Cardiac glycosides potently inhibit C-reactive protein synthesis in human hepatocytes

Elevated plasma levels of C-reactive protein (CRP), the prototype acute-phase protein (APP), are predictive for future cardiovascular events. Controversial evidence suggests that CRP may play a causal role in cardiovascular disease. CRP synthesis inhibition is a potential approach for reducing cardiovascular mortality.We show here that endogenous and plant-derived inhibitors of the Na+/K+-ATPase, i.e. the cardiac glycosides ouabain and digitoxin, inhibit IL-1β- and IL-6-induced APP expression in human hepatoma cells and primary human hepatocytes (PHH) at nanomolar concentrations. Inhibition is demonstrated on transcriptional and on protein level. The molecular target of cardiac glycosides, i.e. the α1 subunit of the Na+/K+-ATPase, is strongly expressed in human hepatocytes. Inhibition of APP synthesis correlates with the potency of cardiac glycosides at the Na+/K+-ATPase. The trigger for APP expression inhibition is an increase in intracellular calcium since the calcium ionophore calcimycin is also active. Qualified specificity of oubain for hepatocellular APP synthesis inhibition is demonstrated by lack of effectivity on IL-1β-induced IL-6 release from primary human coronary artery smooth muscle cells.The inhibitory activity of cardiac glycosides on CRP expression may have important implications for the treatment of cardiovascular disease. Cardiac glycosides may be used for CRP synthesis inhibition in the future.

Studies on mitochondrial macromolecular syntheses in various organs of aging animals labeled with 3H-precursors as revealed by electron microscopic radioautography

In order to study the aging changes of intramitochondrial macromolecular synthesis in various organs of aging animals during the development and aging, 10 groups of developing and aging mice, each consisting of 3 individuals, total 30, from fetal day 19 to postnatal newborn at day 1, 3, 9, 14 and adult at month 1, 2, 6, 12 to 24 were injected with 3H-thymidine a DNA precurson, another 10 groups consisting of 3 individuals, total 30, were injected with 3H-uridine a RNA precursor, and another 10 groups of 30 individuals were injected with 3H-leucine a protein precursor, total 90 individuals. Then, all the animals were sacrificed 1 hr after the injections and the liver tissues, the lung tissues, the kidney tissues, the testis and ovary tissues, the adrenal tissues were taken out, fixed and processed for electron microscopic radioautography. On electron microscopic radioautograms obtained from each animal, ten photographs in respective groups, numbers of mitochondria per cell profile area, numbers of labeled mitochondria per cell and the mitochondrial labeling index (LI) labeled with 3H-thymidine showing DNA synthesis, LI labeled with 3H-uridine showing RNA synthesis, and LI labeled with 3H-leucine showing protein synthesis, in various organs, were counted and the results in various organs in respective aging groups were compared, respectively. From the results, it was demonstrated that the numbers of mitochondria in hepatocytes as well as in 3 zones of the adrenal cortex, the zona glomerulosa, fasciculata and reticularis of mice at various ages increased from fetal day 19 to postnatal month 1 due to development and aging of animals. On the other hand, the numbers of labeled mitochondria and the labeling indices of intramitochondrial DNA syntheses incorporating 3H-thymidine in hepatocytes and 3 zones of cortical cells increased from fetal day 19 to postnatal month 1 and decreased to month 24. The numbers of labeled mitochondria and the labeling indices of intramitochondrial RNA syntheses incorporating 3H-uridine in hepatocytes and 3 zones of cortical cells increased from fetal day 19 to postnatal month 1 and decreased to month 24. The numbers of labeled mitochondria and the labeling indices of intramitochondrial RNA syntheses incorporating 3H-uridine in hepatocytes and 3 ones of cortical cells increased from fetal day 19 to postnatal month 1 and decreased to month 24. Moreover, some other organs such as the lung and the testis were also review and discussed. From the results, it was shown that the activity of intramitochnodrial DNA synthesis, RNA synthesis, and protein synthesis in hepatocytes, adrenal cortical cells, pulmonary cells and testicular cells in developing and aging mice as well as some other organs increased and decreased due to development and aging.