Isolation of a new high molecular weight protein associated with desmin and vimentin filaments from avian embryonic skeletal muscle

Filaments with a diameter of 80-120 A have been prepared from 14-d-old chick embryonic skeletal muscle, using a physiological salt solution and gel filtration chromatography. The filaments obtained are composed of the two known muscle intermediate-filament proteins, vimentin and desmin, as well as the vimentin- and desmin-associated high molecular weight protein, synemin (230,000 mol. wt). In addition, they contain a previously unidentified high molecular weight protein (280,000 mol wt) which differs from synemin by isoelectric point, molecular weight, and immunological reactivity. Immunofluorescence on cultured myogenic cells,using antisera to the 280,000-dalton polypeptide, has revealed that this protein has the same spatial distribution as desmin, vimentin, and synemin in both early myotubes, where it associates with cytoplasmic filaments, and late in myotubes, where it is associated with myofibril Z lines. Examination by immunofluorescence of frozen sections of developing embryonic skeletal muscle reveals a gradual diminution in the presence of the 280,000-dalton protein. The 280,000-dalton protein is undetectable in adult skeletal and smooth muscle, as shown by immunofluorescence and immunoautoradiography. In chick embryonic fibroblasts grown in tissue culture, only a subpopulation of the cells is reactive with antibodies to the 280,000-dalton protein even though all these cells contain vimentin. In the reactive cells, vimentin and the 280,000-dalton polypeptide exhibit an indistinguishable cytoplasmic filamentous network, which aggregates into filamentious bundles when the cells are exposed to colcemid. These results suggest that this newly identified high molecular weight protein is closely associated with intermediate filaments containing either vimentin alone or vimentin, desmin and synemin. The expression of this protein appears to be developmentally regulated and does not appear to parallel the expression of any of the other three intermediate-filament proteins. The absence of the 280,000-dalton polypeptide in adult muscle cells and its gradual reduction during development implies that is probably not required for the maintenance of Z-disk structure after the assembly of the sarcomere.     

Identification of human acetyl-CoA carboxylase isozymes in tissue and in breast cancer cells

• 1.1. In the rat, acetyl-CoA carboxylase (ACC), a rate-limiting enzyme in fatty acid metabolism, exists as at least two different isozymes (M_r 265,000 and 280,000) that display distinct tissue-specific distribution and regulation.
• 2.2. Based on the study of human tissue and human-derived breast cancer cell lines by enzyme isolation and protein blotting techniques, we have now identified two human isoforms of M_r 265,000 (HACC 265) and 275,000 (HACC 275), each of which is homologous to one of the rat isozymes.
• 3.3. Human breast carcinoma cell lines show variable expression of these two isoforms, mirrored in the estimation of ACC acetyl-CoA kinetics.

     

Fatty acid-binding protein and its relation to fatty acid oxidation

A relation between fatty acid oxidation capacity and cytosolic FABP content was found in heart and various muscles of the rat. Other tissues do not show such a relation, since they are involved in more or other pathways of fatty acid metabolism. At postnatal development FABP content and fatty acid oxidation capacity rise concomitantly in heart and quadriceps muscle in contrast to in liver and kidney. A dietary fat content of 40 en. % increased only the FABP content of liver and adipose tissue. Peroxisomal proliferators increased fatty acid oxidation in both liver and kidney, but only the FABP content of liver, and had no effect on heart and skeletal muscle. The FABP content of muscle did not show adaptation to various conditions. Only it increased in fast-twitch muscles upon chronic electrostimulation and endurance training.     

Infusion of a Lipid Emulsion Modulates AMPK and Related Proteins in Rat Liver,Muscle, and Adipose Tissues

The primary objective of this study was to investigate the impact of lipid oversupply on the AMPK pathway in skeletal muscle, liver, and adipose tissue. Male Wistar rats were infused with lipid emulsion (LE) or phosphate‐buffered saline for 5 h/day for 6 days. Muscles exposed to LE for 6 days exhibited increased AMPK and acetyl‐CoA carboxylase (ACC) phosphorylation, along with a greater association between AMPK and Ca²⁺/calmodulin‐dependent protein kinase kinase (CaMKK). No differences in muscle protein phosphatase 2C (PP2C) activity, LKB1 phosphorylation or AMPK and LKB1 association were observed. Muscle ACCβ, and adiponectin receptor 1 (AdipoR1) mRNA levels and PPARγ‐co‐activator 1α (PGC1α) protein levels were also increased in LE‐treated rats. In contrast, AMPK and ACC phosphorylation decreased and PP2C activity increased in rat livers exposed to LE. Hepatic mRNA levels of ACCα, PPARα, AdipoR1, AdipoR2, and sterol regulatory element–binding protein‐1c (SREBP1c) were also reduced after LE infusion. In adipose tissue, there was no significant alteration in AMPK or ACC phosphorylation. These results demonstrate that following lipid oversupply the AMPK pathway was enhanced in rat skeletal muscle while diminished in the liver and was unchanged in adipose tissue. CaMKK in skeletal muscle and PP2C in the liver, at least in part, appear to mediate these alterations. Alterations in AMPK pathway in the liver induced metabolic defects associated with lipid oversupply.     

Fatty acid-binding capacity of cytosolic proteins of various rat tissues: effect of postnatal development, starvation, sex, clofibrate feeding and light cycle

Fatty acid-binding capacity of dealbuminized, delipidated cytosolic proteins from rat tissues was studied with a radiochemical binding assay. Oleate-binding capacity ranges from 1.6 to 4.4 pmol/micrograms cytosolic protein in liver, heart, kidney, adrenal, brain, skeletal muscle and diaphragm. Differences in binding affinity indicate the presence of different fatty acid-binding proteins in these tissues. No change in fatty acid-binding protein content of heart and liver cytosol was observed during postnatal development up to 70 days. Starvation did not affect the fatty acid-binding capacity of heart cytosol, but increased the oleate-binding capacity in liver cytosol. Sex-related differences of binding by heart and liver cytosolic proteins were found with oleate, but not with palmitate. Fatty acid-binding capacity of liver and heart cytosol did not show marked diurnal variation. Clofibrate treatment had different effects on the oleate-binding capacity of cytosolic proteins: an increase in liver and kidney, no change in skeletal muscle and a decrease in heart. The results are discussed in relation to data concerning fatty acid oxidation.     

Phosphorylation control of cardiac acetyl-CoA carboxylase by cAMP-dependent protein kinase and 5'-AMP activated protein kinase.

Acetyl-CoA carboxylase (ACC) is regarded in liver and adipose tissue to be the rate-limiting enzyme for fatty acid biosynthesis; however, in heart tissue it functions as a regulator of fatty acid oxidation. Because the control of fatty acid oxidation is important to the functioning myocardium, the regulation of ACC is a key issue. Two cardiac isoforms of ACC exist, with molecular masses of 265 kDa and 280 kDa (ACC265 and ACC280). In this study, these proteins were purified from rat heart and used in subsequent phosphorylation and immunoprecipitation experiments. Our results demonstrate that 5' AMP-activated protein kinase (AMPK) is able to phosphorylate both ACC265 and ACC280, resulting in an almost complete loss of ACC activity. Although cAMP-dependent protein kinase phosphorylated only ACC280, a dramatic loss of ACC activity was still observed, suggesting that ACC280 contributes most, if not all, of the total heart ACC activity. ACC280 and ACC265 copurified under all experimental conditions, and purification of heart ACC also resulted in the specific copurification of the alpha2 isoform of the catalytic subunit of AMPK. Although both catalytic subunits of AMPK were expressed in crude heart homogenates, our results suggest that alpha2, and not alpha1, is the dominant isoform of AMPK catalytic subunit regulating ACC in the heart. Immunoprecipitation studies demonstrated that specific antibodies for both ACC265 and ACC280 were able to coimmunoprecipitate the alternate isoform along with the alpha2 isoform of AMPK. Taken together, the immunoprecipitation and the purification studies suggest that the two isoforms of ACC in the heart exist in a heterodimeric structure, and that this structure is tightly associated with the alpha2 subunit of AMPK.     

Bimodal activation of acetyl-CoA carboxylase by glutamate

Acetyl-CoA carboxylase (ACC) catalyzes the formation of malonyl-CoA, an essential substrate for fatty acid biosynthesis and a potent inhibitor of fatty acid oxidation. Here, we provide evidence that glutamate may be a physiologically relevant activator of ACC. Glutamate induced the activation of both major isoforms of ACC, prepared from rat liver, heart, or white adipose tissue. In agreement with previous studies, a type 2A protein phosphatase contributed to the effects of glutamate on ACC. However, the protein phosphatase inhibitor microcystin LR did not abolish the effects of glutamate on ACC activity. Moreover, glutamate directly activated purified preparations of ACC when protein phosphatase activity was excluded. Phosphatase-independent ACC activation by glutamate was also reflected by polymerization of the enzyme as judged by size-exclusion chromatography. The sensitivity of ACC to direct activation by glutamate was diminished by treatment in vitro with AMP-activated protein kinase or cAMP-dependent protein kinase or by beta-adrenergic stimulation of intact adipose tissue. We conclude that glutamate, an abundant intracellular amino acid, induces ACC activation through complementary actions as a phosphatase activator and as a direct allosteric ligand for dephosphorylated ACC. This study supports the general hypothesis that amino acids fulfill important roles as signal molecules as well as intermediates in carbon and nitrogen metabolism.     

Tissue specific differences in the fatty acid composition of the marmoset monkey (Callithrix jacchus)

1. The possible relationship between the fatty acid composition of the adipose tissue of the marmoset monkey (Callithrix jacchus) and its dietary lipid intake was examined after a long-term feeding trial. 2. Only the proportions of stearic and linoleic acid in the adipose tissue were similar to those in the diet. The proportions of all other saturated and unsaturated fatty acid components were significantly different thus greatly reducing the potential value of this relationship in the marmoset. 3. The phospholipid fatty acid profiles of cardiac and skeletal muscle, aortae, kidney, liver, lung and brain were also compared to those of the plasma, platelets or red blood cells. 4. With the exception of the liver where the fatty acid profile is similar to that of the plasma, no clear relationships were found between the fatty acid profiles of these tissues and the components of the blood. 5. The fatty acid composition of skeletal muscle was very similar to that of the cardiac muscle of the marmoset, suggesting that muscle biopsy might be useful as an index of cardiac muscle composition.     

Yeast acetyl-CoA carboxylase: in vitro phosphorylation by mammalian and yeast protein kinases

Acetyl-CoA carboxylase (ACC) is regulated in mammalian tissues, in part, by multisite enzyme phosphorylation. Yeast ACC (Y-ACC) has been highly purified from S. cerevisiae by monomeric avidin-Sepharose chromatography, revealing an enzyme subunit species of molecular mass 265,000 Da. Unlike mammalian enzyme, Y-ACC is citrate-independent, and reacts weakly or not at all with a panel of anti-rat liver ACC antibodies. Like rat ACC, Y-ACC is rapidly phosphorylated and inactivated by two mammalian carboxylase kinases, the cAMP-dependent protein kinase and 5'-AMP-stimulated kinase. It is also phosphorylated by rat liver casein kinase II, but without any change in catalytic activity. Three major yeast protein kinases active on ACC have been fractionated; all co-elute with kinases active on casein, but each appears to be a distinct catalytic species. Like the mammalian casein kinases, however, phosphorylation of ACC by these yeast kinases does not alter yeast ACC activity. Taken together, these data indicate that Y-ACC possesses at least two classes of phosphorylation sites, one or more of which acutely regulates enzyme activity. Alterations in Y-ACC phosphorylation in yeast, as in mammalian tissues, could be an important modulator of the rates of fatty acid synthesis.     

Molecular characterization and tissue-specific expression of the acetyl-CoA carboxylase α gene from Grass carp, Ctenopharyngodon idella

Acetyl-CoA carboxylase α (ACC1), the major regulatory enzyme of fatty acid biosynthesis, catalyzes the conversion of acetyl-CoA to malonyl-CoA. The full-length cDNA coding ACC1 isoform was cloned from liver of grass carp. The cDNA obtained was 7515 bp with a 7173 bp open reading frame encoding 2389 amino acids. The ACC1 protein has a calculated molecular weight of 269.2 kDa and isoelectric point of 6.23. Tissue distribution of ACC1 mRNA in brain, mesenteric adipose, spleen, white muscle and liver of grass carp was analyzed by real-time PCR method using β-actin as an internal control for cDNA normalization. The results showed that the expressions of ACC1 mRNA were detected in all examined tissues. Relative expression profile of ACC1 mRNA in liver normalized with β-actin level was 15, 92, 135 and 165-fold compared with the level in brain, white muscle, mesenteric adipose and spleen, respectively. In addition, we present evidence for the presence of two isoforms of ACC1 (265.7 kDa and 267.2 kDa) in grass carp liver that differ from the 269.2 kDa ACC1 by the absence of 34 and 15 amino acids. In conclusion, the liver is one of the main ACC1 producing tissues in grass carp and ACC1 gene was highly homologous to that of mammals.     

Immunochemical analysis of the peroxisomal beta-oxidation enzymes in rat and human heart and skeletal muscle and in skeletal muscle of Zellweger patients

Immunoblot analyses with antibodies against the peroxisomal beta-oxidation enzymes from rat liver showed the presence of these enzymes in rat and human liver and kidney and rat adrenal gland. The bifunctional protein could not be detected in muscle tissues or cultured muscle cells. Acyl-CoA oxidase was detected in rat heart and cultured human muscle cells. 3-Ketoacyl-CoA thiolase was also detected in human and rat heart and skeletal muscle; however, this enzyme was not detectable in skeletal muscle of Zellweger patients, in agreement with the absence of peroxisomal fatty acid oxidation.     

Leptin activates cardiac fatty acid oxidation independent of changes in the AMP-activated protein kinase-acetyl-CoA carboxylase-malonyl-CoA axis

Leptin regulates fatty acid metabolism in liver, skeletal muscle, and pancreas by partitioning fatty acids into oxidation rather than triacylglycerol (TG) storage. Although leptin receptors are present in the heart, it is not known whether leptin also regulates cardiac fatty acid metabolism. To determine whether leptin directly regulates cardiac fatty acid metabolism, isolated working rat hearts were perfused with 0.8 mm [9,10-(3)H]palmitate and 5 mm [1-(14)C]glucose to measure palmitate and glucose oxidation rates. Leptin (60 ng/ml) significantly increased palmitate oxidation rates 60% above control hearts (p < 0.05) and decreased TG content by 33% (p < 0.05) over the 60-min perfusion period. In contrast, there was no difference in glucose oxidation rates between leptin-treated and control hearts. Although leptin did not affect cardiac work, oxygen consumption increased by 30% (p < 0.05) and cardiac efficiency was decreased by 42% (p < 0.05). AMP-activated protein kinase (AMPK) plays a major role in the regulation of cardiac fatty acid oxidation by inhibiting acetyl-CoA carboxylase (ACC) and reducing malonyl-CoA levels. Leptin has also been shown to increase fatty acid oxidation in skeletal muscle through the activation of AMPK. However, we demonstrate that leptin had no significant effect on AMPK activity, AMPK phosphorylation state, ACC activity, or malonyl-CoA levels. AMPK activity and its phosphorylation state were also unaffected after 5 and 10 min of perfusion in the presence of leptin. The addition of insulin (100 microunits/ml) to the perfusate reduced the ability of leptin to increase fatty acid oxidation and decrease cardiac TG content. These data demonstrate for the first time that leptin activates fatty acid oxidation and decreases TG content in the heart. We also show that the effects of leptin in the heart are independent of changes in the AMPK-ACC-malonyl-CoA axis.     

Partial structure and hormonal regulation of rabbit liver inhibitor-1; distribution of inhibitor-1 and inhibitor-2 in rabbit and rat tissues

Inhibitor-1 purified from rabbit liver could not be distinguished from the skeletal muscle protein by chromatographic, electrophoretic and immunological criteria. Amino acid sequences comprising 68% of rabbit liver inhibitor-1 were identical to the skeletal muscle protein indicating that they are products of a single gene. Total inhibitor-1 activity in heat-treated rabbit liver extracts was similar to that in skeletal muscle extracts, and the phosphorylation state of inhibitor-1 increased from 14% to 42% in rabbit liver in vivo after an intravenous injection of glucagon. Monospecific antibodies to rabbit skeletal muscle inhibitor-1 recognised a single major protein of identical electrophoretic mobility (26 kDa) in each rabbit tissue examined (skeletal muscle, liver, brain, heart, kidney, uterus and adipose). The antibodies also recognised a single major (30 kDa) protein in the same rat tissues, except liver. The results show that while there are interspecies differences in apparent molecular mass, inhibitor-1 is likely to be the same gene product in each mammalian tissue. Inhibitor-1 was not detected in rat liver, either by activity measurements or immunoblotting, irrespective of the age, sex or strain of the animals. Immunoblotting also failed to detect inhibitor-1 in mouse liver, although it was present in guinea pig, porcine and sheep liver. The absence of inhibitor-1 in rat liver indicates that phosphorylation of this protein cannot underlie the increased phosphorylation of hydroxymethylglutaryl-CoA reductase observed after stimulation by glucagon. Monospecific antibodies to rabbit skeletal muscle inhibitor-2 recognised a 31 kDa protein in each rabbit tissue, and a 33 kDa protein in all rat tissues including liver. The results suggest that inhibitor-2 is the same gene product in each mammalian tissue.     

The appearance of a 34,000-dalton inhibitor of calpain (Ca2+-dependent cysteine proteinase) in rat liver after the administration of phenylhydrazine

A 34,000-dalton inhibitor of calpain (Ca2+-dependent cysteine proteinase) was found in the cytosol of anemic rat liver. When phenylhydrazine hydrochloride was continuously administered to rats, a 280,000-dalton calpain inhibitor that existed originally in the liver gradually disappeared within two weeks and, concomitantly, a 34,000-dalton inhibitor appeared. The purified 34,000-dalton inhibitor resembles 280,000-dalton inhibitor in that both are heat-stable proteins and do not inhibit papain and trypsin. Unlike the protomers of a 280,000-dalton inhibitor, 34,000-dalton inhibitor does not show any sign of self-association.     

Purification and partial sequence analysis of pp185, the major cellular substrate of the insulin receptor tyrosine kinase

Insulin stimulates the tyrosine phosphorylation of a 185-kDa putative cytosolic substrate protein (pp185) in diverse cell types. After intravenous insulin infusion into the live intact rat, pp185 and the 95-kDa insulin receptor beta-subunit were the major proteins that tyrosine phosphorylated in liver, skeletal muscle, and adipose tissue. Both proteins were maximally phosphorylated within 30 s, and both increased in phosphotyrosine content in parallel with increasing insulin dose. However, pp185 tyrosine phosphorylation was transient, with almost complete dephosphorylation within 2-3 min despite continued insulin stimulation. To identify pp185 directly, we purified pp185 from insulin-stimulated rat liver, using a denaturation-based extraction procedure that blocks endogenous protein phosphatases and thus allows a high yield, single step isolation of phosphotyrosyl proteins by anti-phosphotyrosine antibody immunoaffinity absorption. From 50 rat livers, 50-100 pmol of pp185 was isolated. Edman degradation of seven internal tryptic peptide fragments of pp185 yielded novel amino acid sequences, indicating that pp185 is a new protein. Antipeptide antibodies were raised which specifically recognize a single, 185-kDa insulin-stimulated phosphotyrosyl protein in liver, skeletal muscle, adipose tissue, and several cultured cell lines. These results indicate that pp185 is expressed in a variety of insulin-responsive tissues, is the major protein rapidly tyrosine phosphorylated under physiological conditions in the intact animal, and also provide a route for cloning the pp185 gene and elucidating the function of pp185 in insulin signal transduction.     

Coordinate regulation of malonyl-CoA decarboxylase,sn-glycerol-3-phosphate acyltransferase,and acetyl-CoA carboxylase by AMP-activated protein kinase in rat tissues in response to exercise

Changes in the concentration of malonyl-CoA in many tissues have been related to alterations in the activity of acetyl-CoA carboxylase (ACC), the rate-limiting enzyme in its formation. In contrast, little is known about the physiological role of malonyl-CoA decarboxylase (MCD), an enzyme responsible for malonyl-CoA catabolism. In this study, we examined the effects of voluntary exercise on MCD activity in rat liver, skeletal muscle, and adipose tissue. In addition, the activity of sn-glycerol-3-phosphate acyltransferase (GPAT), which like MCD and ACC can be regulated by AMP-activated protein kinase (AMPK), was assayed. Thirty min after the completion of a treadmill run, MCD activity was increased approximately 2-fold, malonyl-CoA levels were reduced, and ACC and GPAT activities were diminished by 50% in muscle and liver. These events appeared to be mediated via activation of AMPK since: 1) AMPK activity was concurrently increased by exercise in both tissues; 2) similar findings were observed after the injection of 5-amino 4 imidazole carboxamide, an AMPK activator; 3) changes in the activity of GPAT and ACC paralleled that of MCD; and 4) the increase in MCD activity in muscle was reversed in vitro by incubating immunoprecipitated enzyme from the exercised muscle with protein phosphatase 2A, and it was reproduced by incubating immunopurified MCD from resting muscle with purified AMPK. An unexpected finding was that exercise caused similar changes in the activities of ACC, MCD, GPAT, and AMPK and the concentration of malonyl-CoA in adipose tissue. In conclusion: MCD, GPAT, and ACC are coordinately regulated by AMPK in liver and adipose tissue in response to exercise, and except for GPAT, also in muscle. The results suggest that AMPK activation plays a major role in regulating lipid metabolism in many cells following exercise. They also suggest that in each of them, it acts to increase fatty acid oxidation and decrease its esterification.     

Regulation of AMP-activated protein kinase and acetyl-CoA carboxylase phosphorylation by palmitate in skeletal muscle cells

The purpose of this study was to investigate the effects of long-chain fatty acids (LCFAs) on AMP-activated protein kinase (AMPK) and acetyl-coenzyme A carboxylase (ACC) phosphorylation and beta-oxidation in skeletal muscle. L6 rat skeletal muscle cells were exposed to various concentrations of palmitate (1-800 microM). Subsequently, ACC and AMPK phosphorylation and fatty acid oxidation were measured. A 2-fold increase in both AMPK and ACC phosphorylation was observed in the presence of palmitate concentrations as low as 10 microM, which was also accompanied by a significant increase in fatty acid oxidation. The effect of palmitate on AMPK and ACC phosphorylation was dose-dependent, reaching maximum increases of 3.5- and 4.5-fold, respectively. Interestingly, ACC phosphorylation was coupled with AMPK activation at palmitate concentrations ranging from 10 to 100 microM; however, at concentrations >200 microM, ACC phosphorylation and fatty acid oxidation remained high even after AMPK phosphorylation was completely prevented by the use of a selective AMPK inhibitor. This indicates that LCFAs regulate ACC activity by AMPK-dependent and -independent mechanisms, based on their abundance in skeletal muscle cells. Here, we provide novel evidence that the AMPK/ACC pathway may operate as a mechanism to sense and respond to the lipid energy charge of skeletal muscle cells.     

Tissue expression of three structurally different fatty acid binding proteins from rat heart muscle, liver, and intestine

Three structurally different 14-15 kDa fatty acid binding proteins have have been purified from rat liver, small intestinal epithelium, and heart muscle, and were quantitated using specific antisera in rat tissues. Heart muscle fatty acid binding protein comprised 5% of heart muscle cytosol protein and was also expressed in stomach, muscle, testis, ovary, kidney, brain, and adipose tissue, a pattern distinct from both liver protein (expressed in liver, small and large intestinal epithelium, and adipose tissue) and intestinal protein (expressed in small and large intestinal epithelium and stomach). Distinctive patterns of tissue expression of the three different fatty acid binding proteins suggest that they may perform different specific functions in fatty acid transport and metabolism.     

Effects of starvation on the tissular lipogenic rate in the obese Zucker rat.

The lipogenic rate of the obese rats was significantly higher than that of the lean rats in liver, white adipose tissue, skeletal muscle, heart and carcass. In the lean rats, a 24 h starvation period caused a significant decrease in the lipogenic rate of white adipose tissue and skeletal muscle while it increased that of heart, brain and brown adipose tissue. In the obese rats, starvation decreased the lipogenic rate in liver, skeletal muscle, white adipose tissue, brown adipose tissue and carcass. In spite of this, liver and skeletal muscle showed higher rates of lipid synthesis than the corresponding fed lean. It is concluded that starvation induces a qualitatively similar response in the obese versus the lean rat although the total lipogenic capacity of the animal is still higher.     

Changes in fatty acid transport and transporters are related to the severity of insulin deficiency

We have examined the effects of streptozotocin (STZ)-induced diabetes (moderate and severe) on fatty acid transport and fatty acid transporter (FAT/CD36) and plasma membrane-bound fatty acid binding protein (FABPpm) expression, at the mRNA and protein level, as well as their plasmalemmal localization. These studies have shown that, with STZ-induced diabetes, 1) fatty acid transport across the plasma membrane is increased in heart, skeletal muscle, and adipose tissue and is reduced in liver; 2) changes in fatty acid transport are generally not associated with changes in fatty acid transporter mRNAs, except in the heart; 3) increases in fatty acid transport in heart and skeletal muscle occurred with concomitant increases in plasma membrane FAT/CD36, whereas in contrast, the increase and decrease in fatty acid transport in adipose tissue and liver, respectively, were accompanied by concomitant increments and reductions in plasma membrane FABPpm; and finally, 4) the increases in plasma membrane transporters (FAT/CD36 in heart and skeletal muscle; FABPpm in adipose tissue) were attributable to their increased expression, whereas in liver, the reduced plasma membrane FABPpm appeared to be due to its relocation within the cell in the face of slightly increased expression. Taken together, STZ-induced changes in fatty acid uptake demonstrate a complex and tissue-specific pattern, involving different fatty acid transporters in different tissues, in combination with different underlying mechanisms to alter their surface abundance.