CD36/Fatty Acid Translocase in Rats: Distribution, Isolation from Hepatocytes, and Comparison with the Scavenger Receptor SR-B1

Abstract

SUMMARY:The new mAb UA009 recognizes an antigen expressed by microvascular endothelium, by lymphatic endothelium, and by some epithelia in a number of organs, including the small intestine, lactating mammary gland, kidney, lung, sebaceous glands, and circumvallate papillae of the tongue. This antigen is also expressed abundantly in the splenic red pulp and marginal zone and by monocytes, macrophages, and erythrocytes (but not by platelets). Among tissues that store or metabolize fatty acids, the antigen is expressed by adipocytes, cardiomyocytes, and red skeletal muscle. Importantly, it is expressed by steroidogenic cells in the adrenal gland, testis, and ovary, whereas in the liver it is expressed by hepatocytes in a pattern that is dependent on gender and genetic background. mAb UA009 immunoprecipitated a mol wt 85-kDa surface protein from detergent extracts of hepatocytes from Dark Agouti female rats. The N-terminal amino acid sequence of this protein was identical to fatty acid translocase (FAT), the rat cluster of differentiation 36 (CD36) ortholog. The mAb also reacted with COS-7 cells transfected with cDNA encoding FAT. cDNAs encoding a CD36/FAT-like polypeptide were prepared from both liver and heart RNA by RT-PCR. The nucleotide sequences obtained from these cDNAs (Dark Agouti rats) revealed identity and 99% similarity, respectively, with the published sequences of Cd36/Fat in rats of the Wistar and Sprague-Dawley strains. The absence of the UA009 antigen in CD36/FAT-deficient SHR/N rats confirmed the identity of the UA009 antigen and CD36/FAT. We suggest that CD36/FAT might function in the liver as a sex-regulated accessory molecule, either in reverse cholesterol transport and/or in fatty acid uptake. (Lab Invest 2003, 83:317-332).

CD36: Implications in cardiovascular disease

“…These rats are hypertensive, insulin resistant and have impaired fatty acid uptake (Pravenec, et al, 1999). The CD36 mutation correlates best with the impaired fatty acid uptake phenotype, which then may affect insulin resistance in this model (especially given the expression of CD36 in liver) (Pravenec, et al, 1999,Collison, et al, 2000,Pravenec, et al, 2001,Hajri, et al, 2001,Zhang, et al, 2003. Indeed, work using CD36 KO mice showed secondary effects to decreased peripheral fatty acid uptake.…”

FAT/CD36 is localized in sarcolemma and in vesicle-like structures in subsarcolemma regions but not in mitochondria

“…These fi ndings furthermore suggest that FAT/CD36 might not be essential to preserve mitochondrial ability to oxidize LCFA. In addition, previous attempts to detect intracellular FAT/ CD36 in human ( 14 ), rat ( 15 ), and mouse ( 16 ) muscle cross-sections using microscopy approaches have only been able to detect FAT/CD36 in plasma membranes. Interestingly, Keizer et al ( 17 ) detected small intracellular FAT/CD36 structures using fl uorescence immunohistochemistry; however, when costaining with the mitochondrial marker cytochrome C, no FAT/CD36 staining in mitochondria was observed, supporting the view that FAT/ CD36 is not present in mitochondria in the basal state.…”

Flow Cytometry in Preclinical Toxicology/Safety Assessment

“…Since DiI-Ac-LDL is ingested through binding to scavenger receptors, it was postulated that a similar cell population could be identified using an antibody against said scavenger receptor. CD36 is a type B scavenger receptor and the rat ortholog, fatty acid translocase (FAT), has been shown to be present on endothelium [19]. Rat blood samples costained with DiI-Ac-LDL and anti-CD36 exhibited $80% overlap between labels, therefore anti-CD36 antibody replaced DiI-Ac-LDL in all subsequent experiments.…”