Whodunnit?

White, Benjamin

doi:10.1038/38592

Cited by 6 publications

(11 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Primary Hepatocyte Culture-Hepatocytes were isolated from AdCre1-treated mice by White's method (22) except that the perfusion was done on an anesthetized animal through the portal vein instead of on excised liver. A pulse-chase experiment using […”

Section: Methodsmentioning

confidence: 99%

Liver-specific Inactivation of the Abetalipoproteinemia Gene Completely Abrogates Very Low Density Lipoprotein/Low Density Lipoprotein Production in a Viable Conditional Knockout Mouse

Chang

Liao²,

et al. 1999

Journal of Biological Chemistry

119

100

View full text Add to dashboard Cite

Section: Methodsmentioning

confidence: 99%

Liver-specific Inactivation of the Abetalipoproteinemia Gene Completely Abrogates Very Low Density Lipoprotein/Low Density Lipoprotein Production in a Viable Conditional Knockout Mouse

Chang

Liao²,

et al. 1999

Journal of Biological Chemistry

119

100

View full text Add to dashboard Cite

“…Hepatocyte Isolation-Hepatocytes from L-FABPϩ/ϩ and L-FABPϪ/Ϫ mice were isolated as described earlier (27). Briefly, mice were euthanized by CO 2 asphyxiation, and the livers were removed and perfused first with Buffer A (10 mM Hepes, pH 7.4, in calcium/magnesium-free Hanks' buffered saline solution (HBSS), gentamycin sulfate (1 mg/ml medium), and 0.5 mM EGTA) for 10 min (3 ml/min), followed by Buffer B (Buffer A without EGTA, supplemented with 5 mM CaCl 2 and 0.2 mg/ml collagenase B) for an additional 10 min.…”

Section: Methodsmentioning

confidence: 99%

Liver Fatty Acid-binding Protein Gene Ablation Inhibits Branched-chain Fatty Acid Metabolism in Cultured Primary Hepatocytes

Atshaves

McIntosh

Lyuksyutova

et al. 2004

Journal of Biological Chemistry

155

View full text Add to dashboard Cite

Whereas the role of liver fatty acid-binding protein (L-FABP) in the uptake, transport, mitochondrial oxidation, and esterification of normal straight-chain fatty acids has been studied extensively, almost nothing is known regarding the function of L-FABP in peroxisomal oxidation and metabolism of branched-chain fatty acids. Therefore, phytanic acid (most common dietary branched-chain fatty acid) was chosen to address these issues in cultured primary hepatocytes isolated from livers of L-FABP gene-ablated (؊/؊) and wild type (؉/؉) mice. These studies provided three new insights: First, L-FABP gene ablation reduced maximal, but not initial, uptake of phytanic acid 3.2-fold. Initial uptake of phytanic acid uptake was unaltered apparently due to concomitant 5. , 7), specific effects of L-FABP gene ablation on liver uptake of straight-chain fatty acid and liver lipid distribution are complex, apparently depending on feeding status, gender, and age of the mice (6 -9).Although relatively little is known about the role of L-FABP in the oxidation of straight-chain fatty acids, which occurs primarily in mitochondria (reviewed in Refs. 1-3), recent studies with L-FABP gene-ablated mice suggest that L-FABP may affect liver oxidation of straight-chain fatty acids under high fatty acid load. Under fed conditions, serum free fatty acid levels were found to be low, and ␤-hydroxybutyrate levels were unaltered in L-FABP (Ϫ/Ϫ) male or female mice, suggesting that L-FABP may not play a role in fatty acid oxidation (8, 9). However, under starvation conditions, serum fatty acid levels were highly elevated, and serum ␤-hydroxybutyrate levels were reduced. These findings led to the conclusion that under fasting conditions L-FABP gene ablation reduces fatty acid oxidation (8, 9). However, other in vitro studies measuring fatty acid oxidation and ␤-hydroxybutyrate production in liver homogenates showed that L-FABP gene ablation had no effect on oxidation of straight-chain, radiolabeled palmitic acid at high levels (1 mM) (9). In contrast, when fatty acid oxidation and ␤-hydroxybutyrate production were measured with hepatocyte suspensions freshly isolated from female mice, L-FABP gene ablation reduced oxidation of high levels (1 mM) of straight-chain palmitic acid by about 30% (9). Whereas the above results appear contradictory, the intact hepatocyte and in vivo data suggest that L-FABP gene ablation does not affect oxidization of straight-chain fatty acids under normal fed conditions when serum fatty acid levels are low but may do so when serum fatty acids are high as in starvation.In contrast to the above studies with straight-chain fatty acids, almost nothing is known regarding potential roles of L-FABP in the uptake, oxidation, and esterification of branched-chain fatty acids. The most common dietary branched-chain fatty acid, phytanic acid, is produced by ruminants in the gut by bacterial cleavage of the side chain of chlorophyll to yield phytol, followed by conversion to phytanic acid (reviewed in Ref. 10). Consequently, levels of...

show abstract

“…We found that human apo(a) is also inefficiently secreted from primary hepatocytes, and a large portion of the protein is retained inside the cell and degraded (31).…”

mentioning

confidence: 95%

“…2 Throughout this paper, these mice are referred to as Lp(a) transgenic mice. Hepatocytes were isolated and cultured in a serum-free medium (SFM) formulation exactly as described previously (31). All experiments were performed with cells that had been in culture for 48 -72 h.…”

Section: Materials-[mentioning

confidence: 99%

6-Aminohexanoic Acid as a Chemical Chaperone for Apolipoprotein(a)

Wang

White²

1999

Journal of Biological Chemistry

View full text Add to dashboard Cite

Apolipoprotein (a) (apo(a)) is a component of the atherogenic lipoprotein, Lp(a). The efficiency with which apo(a) escapes the endoplasmic reticulum (ER)and is secreted by the liver is a major determinant of plasma Lp(a) levels. Apo(a) contains a series of domains homologous to plasminogen kringle (K) 4, each of which possesses a potential lysine-binding site. By using primary mouse hepatocytes expressing a 17K4 human apo(a) protein, we found that high concentrations (25-200 mM) of the lysine analog, 6-aminohexanoic acid (6AHA), increased apo(a) secretion 8 -14-fold. This was accompanied by a decrease in apo(a) presecretory degradation. 6AHA inhibited accumulation of apo(a) in the ER induced by the proteasome inhibitor, lactacystin. Thus, 6AHA appeared to inhibit degradation by increasing apo(a) export from the ER. Significantly, 6AHA overcame the block in apo(a) secretion induced by the ER glucosidase inhibitor, castanospermine. 6AHA may therefore circumvent the requirement for calnexin and calreticulin interaction in apo(a) secretion. Sucrose gradients and a gel-based folding assay were unable to detect any influence of 6AHA on apo(a) folding. However, non-covalent or small, disulfide-dependent changes in apo(a) conformation would not be detected in these assays. Proline also increased the efficiency of apo(a) secretion. We propose that 6AHA and proline can act as chemical chaperones for apo(a). Apolipoprotein (a) (apo(a))1 is a component of lipoprotein (a) (Lp(a)). Lp(a) is an unusual lipoprotein found only in the plasma of humans, old world primates (1), and the hedghog (2). Lp(a) consists of low density lipoprotein (LDL) in which apoB100, the sole protein component of LDL, is attached to apo(a) by a disulfide bond (3). Apo(a) is synthesized by the liver (4 -6) and associates with LDL in plasma to form Lp(a) (7-9). Plasma Lp(a) levels are determined by Lp(a) production rate (10, 11) and vary among individuals from Ͻ1 to Ͼ100 mg/dl (12). More than 90% of this variation is determined by inheritance at the apo(a) gene locus (13). High Lp(a) levels (Ͼ30 mg/dl) are associated with an increased incidence of various cardiovascular diseases (14). The mechanisms that determine the rate of apo(a) secretion by the liver are therefore of considerable interest.Apo(a) is homologous to plasminogen and consists of multiple domains with homology to plasminogen kringle (K) 4, followed by domains homologous to the plasminogen K5 and protease domains (15). As many as 34 different apo(a) size isoforms (from Ͻ300 to Ͼ800 kDa) exist due to variation in the number of K4 domains encoded in the apo(a) gene (16). There is an inverse correlation between apo(a) size and plasma Lp(a) level, accounting for 19 -70% of the variation in plasma Lp(a) levels depending on the ethnic group (17). Sequence polymorphism independent of K4 number also exists at the apo(a) gene locus, accounting for the remaining contribution of the apo(a) gene to plasma Lp(a) levels (18).The K4 domains in apo(a) are of 10 types based on amino acid differences (19). E...

show abstract

Whodunnit?

Cited by 6 publications

References 4 publications

Liver-specific Inactivation of the Abetalipoproteinemia Gene Completely Abrogates Very Low Density Lipoprotein/Low Density Lipoprotein Production in a Viable Conditional Knockout Mouse

Liver-specific Inactivation of the Abetalipoproteinemia Gene Completely Abrogates Very Low Density Lipoprotein/Low Density Lipoprotein Production in a Viable Conditional Knockout Mouse

Liver Fatty Acid-binding Protein Gene Ablation Inhibits Branched-chain Fatty Acid Metabolism in Cultured Primary Hepatocytes

6-Aminohexanoic Acid as a Chemical Chaperone for Apolipoprotein(a)

Contact Info

Product

Resources

About