Mouse Liver Parenchymal Cells Research Articles

Enhanced DNA-repair capacity and resistance to chemically induced carcinogenesis upon deletion of the phosphatase regulator NIPP1

Nuclear Inhibitor of PP1 (NIPP1) is a conserved regulatory subunit of protein phosphatase PP1. The selective deletion of NIPP1 in mouse liver parenchymal cells or skin epidermal cells culminates in a late-onset hyperproliferation of a subset of resident progenitor cells. Although a hyperplastic phenotype is usually tumor promoting, we show here that the absence of NIPP1 conferred a strong resistance to chemically induced hepatocellular or skin carcinoma. The ablation of NIPP1 did not affect the metabolism of the administered mutagens (diethylnitrosamine or 7,12-dimethylbenz[a]anthracene), but reduced the conversion of mutagen-induced covalent DNA modifications into cancer-initiating mutations. This reduced sensitivity to mutagens correlated with an enhanced DNA-damage response and an augmented expression of rate-limiting DNA-repair proteins (MGMT in liver, XPD and XPG in skin), hinting at an increased DNA-repair capacity. Our data identify NIPP1 as a repressor of DNA repair and as a promising target for novel cancer prevention and treatment therapies.

Lipid deposition in liver cells: The influence of short form augmenter of liver regeneration

The short form augmenter of liver regeneration (sfALR) is a novel human hepatotrophic growth factor. The aim of this study was to investigate the potential role of sfALR in NAFLD. The free fatty acids (FFA) induced lipid accumulation in mouse liver parenchymal cells was examined by Oil Red O staining and triglyceride level determination. The cell cycle was determined by flow cytometry and the proliferation was assessed by CCK8. The expression levels of gfer, miR-122, srebp-1c, fas, dgat2, acc1 and Lrp1B were assessed by quantitative real-time PCR. Furthermore, the MAPK pathway was detected by western blot. The results showed that sfALR could alleviate the lipid accumulation in mice both in vivo and in vitro. sfALR relieved the proliferation inhibition and G2 arrest of mouse liver parenchymal cells induced by FFAs. Free fatty acids affected gfer expression in a time-and dose-dependent way. And sfALR suppressed JNK activation, increased miR-122 level and reduced fatty acid synthesis-related gene expression. These findings suggested that sfALR could alleviate the severity of fatty liver in mice.

Characterization of the Hepatic Cellular Uptake of α1-Acid Glycoprotein (AGP), Part 1: A Peptide Moiety of Human AGP Is Recognized by the Hemoglobin β-Chain on Mouse Liver Parenchymal Cells

Human α(1) -acid glycoprotein (AGP), a serum glycoprotein, is known to have anti-inflammatory activity. We recently reported that AGP was mainly incorporated into the liver in mice via a receptor-mediated pathway, although the mechanism for this was largely unknown. The objective of this study was to identify the specific cellular surface protein that recognizes the peptide moiety of AGP. Pharmacokinetic studies of (111) In-AGP and (111) In -recombinant glycan-deficient AGP (rAGP) in mice demonstrated that both AGPs are mainly distributed to the liver and kidney, but hepatic and renal uptake clearance of rAGP was higher than that for AGP. Hepatic uptake of rAGP was inhibited in the presence of 100-fold excess of unlabeled AGP, indicating that the hepatic uptake of rAGP shared a common route with that of AGP and that it recognized the peptide moiety of AGPs. In ligand blotting analyses using crude cellular membrane fraction of mice liver, a band corresponding to a 16 kDa protein was observed to bind to both AGPs. Interestingly, matrix-assisted laser desorption ionization-time-of-flight mass spectrometry MALDI-TOF-MS and western blotting analyses indicated that this 16 kDa protein is the hemoglobin β-chain (HBB). It, therefore, appears that HBB is associated with the hepatic uptake of AGP via a direct interaction with its peptide moiety.

Induction of Glutathione S-Transferase II in Mouse Liver Parenchymal Cells by 3453'4'-Pentachlorobiphenyl-Comparison between C57BL Strain and DBA Strain (Proceedings of the 20th Symposium on Toxicology and Environmental Health)

Induction of Glutathione S-Transferase II in Mouse Liver Parenchymal Cells by 3453'4'-Pentachlorobiphenyl-Comparison between C57BL Strain and DBA Strain (Proceedings of the 20th Symposium on Toxicology and Environmental Health)

Effect of dietary restriction on the degradation of proteins in senescent mouse liver parenchymal cells in culture

We previously reported that the half-life of protein degradation in cells from old mice is about 50% longer than that in cells from young or middle-aged ones. In the present study we investigated the degradation rate of microinjected proteins (horseradish peroxidase (HRP) and ovalbumin (OVA)) and pulse-labeled proteins in hepatocytes from dietary-restricted old mice. Dietary restriction was initiated when mice were 23 months of age and performed in two steps (first 80% and then 60% of the ad libitum intake), the total period being 70 days. Hepatocytes were isolated from mice fed a restricted diet and fed ad libitum. The half-lives of HRP, OVA, and pulse-labelled proteins in the hepatocytes from mice fed a restricted diet were about 40% shorter than those in the cells from mice fed ad libitum. These values were close to those in the cells of young animals. These results are discussed in relation to our previous findings that a similar regimen reduces the percentage of heat-labile enzymes accumulated in tissues of aged animals.

Age-related change in the degradation rate of ovalbumin microinjected into mouse liver parenchymal cells

Change in the degradation rate of ovalbumin (OVA) microinjected into liver parenchymal cells isolated from mice of various ages was studied. OVA was injected by osmotic lysis of pinosomes and the amount of OVA was determined by immunoblotting using purified antibody to OVA. Cellular activity as judged by rates of protein synthesis and degradation of pulse-labeled proteins was not affected by the injection. To localize injected OVA in the cells, cell extracts were fractionated by differential centrifugation and the amount of OVA and the activity of β- d-galactosidase as a lysosomal marker enzyme of each fraction were determined. The ovalbumin was mostly found in the soluble fraction, while the β- d-galactosidase activity was found in the particulate fraction, indicating that the ovalbumin was spread in the cytosol but was not present in the pinosomes or lysosomes. The average half-lives of OVA were 106, 113, and 164 h in the cells from young (3.5–6.5 months), middle-aged (13.5–20.0 months), and old (24.5–30.5 months) mice, respectively. Thus, the halflife of ovalbumin in the cells of senescent mice was about 50% longer than that in the cells of young or middle-aged mice. These results are in good agreement with those of our previous investigation, which showed that the half-life of inactivation of horseradish peroxidase was extended by about 50% in the hepatocytes from old mice ( Ishigami and Goto, 1988, Mech. Ageing Dev., 46, 125–133 ).

Reversible inhibition of RNA synthesis and irreversible inhibition of protein synthesis by D-galactosamine in isolated mouse hepatocytes.

The inhibition of RNA synthesis of isolated mouse liver parenchymal cells caused by 10 mM D-galactosamine was reversible, while the inhibition of protein synthesis remained unaltered after the removal of galactosamine. 10(-5)M epinephrine and 10(07)M glucagon have been shown to decrease aminoglycogen formation and thus to reduce the inhibitory effect of galactosamine on protein synthesis (II). However, these hormones did not decrease the inhibition of RNA synthesis. 10 mM D-galactosamine did not effect the nucleoside and amino acid incorporation of isolated non-parenchymal mouse liver cells. The predominant role of aminoglycogen in the inhibition of protein synthesis in galactosamine induced liver injury is discussed.

Action of DTPA on Hepatic Plutonium: II. DTPA-Induced Removal of Monomeric Plutonium from Mouse Liver Parenchymal Cells

Liver parenchymal cells were isolated 6 and 24 hr following the administration of diethylenetriaminepentaacetic acid (DTPA, 0.25 mmole/kg) to mice previously injected with /sup 239/Pu-citrate (4.4 ..mu..Ci/kg). Isolated parenchymal cells contained 440 dpm Pu/10/sup 6/ cells at 24 hr after Pu injection, just prior to DTPA administration. The PU content decreased to 330 dpm/10/sup 6/ cells at 6 hr and 140 dpm/10/sup 6/ cells at 24 hr after DTPA administration. Thus DTPA induced a striking decrease in the Pu content of isolated liver parenchymal cells. Parenchymal cells isolated from control mice not treated with DTPA changed little in Pu content from 24 to 48 hr after Pu injection. By 24 hr after DTPA treatment, the decrease in the Pu content of isolated liver parenchymal cells could account for the DTPA-induced release of Pu from the intact liver. Thus in the liver DTPA appears to act preferentially on the Pu associated with parenchymal cells. Liver parenchymal cells isolated 6 hr after DTPA administration and containing 330 dpm Pu/10/sup 6/ cells were incubated in vitro in the absence of added DTPA. After 18 hr of incubation the cells contained 130 dpm Pu/10/sup 6/ cells. This level corresponds to the level observed inmore » cells isolated 24 hr after DTPA administration. Cells isolated from untreated mice lost only 15% of their Pu content during a similar in vitro incubation. Thus, by 6 hr after DTPA administration to the mouse, isolated liver parenchymal cells appeared to retain their ability to release Pu in vitro with no need for additional exposure to DTPA. The physiological significance of this finding is discussed.« less

Studies on vinblastine-induced autophagocytosis in the mouse liver.I. The relation of lysosomal changes to general injurious effects.

Intraperitoneal injection of two doses of vinblastine (10 mg/kg and 50 mg/kg) induced a prominent formation of autophagic vacuoles in mouse liver parenchymal cells in 4 h. Clearly recognizable organelles were seen inside these vacuoles. The amount of autophagy was dependent on doses in that autophagosomes almost disappeared within 12 h with the low dose, whereas with the high dose the -ells were filled with residual bodies. Defecation of lysosomal material was ovserved into the sinusoidal lumen 12 h after injection with high dose. The total activities of lysosomal enzymes acid phosphatase, beta-galactosidase, and beta-acetylglucosaminidase did not change in the liver after vinblastine administration. The soluble activities of beta-galactosidase and beta-glucosaminidase were elevated with the high dose 12 h after injection, indicating labilization of the lysosomal membranes. Simultaneously the activities of the three lysosomal enzymes were elevated in the serum. The injurious effect of VBL appeared in light-and electron microscopic levels indicating diffuse necrosis of the liver lobules with the high gose within 12 h, fat accumulation in the cells, accumulation of secretory vesicles containing very low density lipoprotein particles, partial dilatation, vesiculation of endoplasmic reticulum and dilatation of Golgi cisternae. The serum GOT and CPK levels were also elevated

Association of Plutonium with Isolated Liver Parenchymal Cells Following Injection of Monomeric Plutonium into Mice

The early kinetics of the association of plutonium with liver parenchymal cells was measured after intravenous injection of monomeric plutonium (/sup 239/Pu(IV)citrate) into CF 1 female mice. The amount of plutonium associated with isolated liver parenchymal cells and the total liver plutonium concentration were determined at times ranging from 1 hr to 6 days after plutonium administration. The number of parenchymal cells per gram mouse liver as well as the ratios of parenchymal cell-associated plutonium (DPM/isolated cell) to total plutonium concentration (DPM/g liver) were calculated in order to determine the percentage of the liver burden associated with parenchymal cells. Up to 6 days, the concentration of monomeric plutonium associated with isolated mouse liver parenchymal cells increased more slowly than the total liver plutonium concentration. The latter reached a maximum by 5 hr and decreased only slightly by 6 days. In contrast, the fraction of the liver burden associated with parenchymal cells increased from 29 percent at 5 hr to 70 percent at 6 days after plutonium administration.

Ageing of mouse liver lysosomes. An experimental study using indigestible marker substances.

Lysosomes in mouse liver parenchymal cells have been marked by intravenous injection of Thorotrast. They were subsequently followed in a time sequence from five hours up to sixteen weeks after injection. At two days after injection the majority of the lysosomes was heavily loaded with marker particles, while endocytosis was no longer observed. From six days after injection Thorotrast was partly accumulated in very large lysosomes (conglomerates) with mean diameters up to 2.5 μm. As the time after injection advanced the Thorotrast content of the cells was reduced while most of the remaining marker substance became concentrated in the conglomerates. Many Thorotrast conglomerates were shown to contain acid phosphatase and some of them were able to fuse with functionally younger lysosomes which were marked with colloidal gold. Morphometric analysis showed an increase in the volume density of the dense body population between 0 and 2 days after injection, followed by a decrease between 2 and 11 days. The observed decrease is probably caused by exocytosis of the contents of Thorotrast containing lysosomes in bile capillaries.

Electrogenic sodium pump in mouse liver parenchymal cells.

Readmitting potassium to potassium-deprived mouse liver segments during intracellular microelectrode recording caused an increase in membrane potential and a gradual reduction in amplitude of electrotonic potentials set up by current pulses applied to another liver cell some distance away. Readmitting K in a high concentration (100 mM) caused a transient hyperpolarization followed by depolarization. The transient hyperpolarization was abolished by Strophanthin-G.

Quantitative Changes in Mouse Liver Ultrastructure Following Cortisone and Insulin Administration

Linear analysis of whole cell montages provided the basis for determining the following in mouse liver parenchymal cells: the cytoplasmic volume fraction of mitochondria, lysosomes, lipid, glycogen, and cytoplasmic matrix; the membrane profile concentration; and mitochondrial number and dimensions (including a shape coefficient). Included are a number of studies of the validity of the methods used, some new statistical considerations, and a new, more objective method of determining mitochondrial shape.