The fatty acid-binding proteins (FABPs) are among the most abundant cytoplasmic constituents of
parenchymal cells . These small cytosolic proteins enhance the intracellular transport and
metabolism of fatty acids and may show an affinity for other ligands, such as retinoic acid, bile acids,
or prostaglandins. Different genes encode at least eight types of FABPs, which differ in their
specific binding properties and have each been named after the tissue of major occurrence.
NCBI Summary:
The intracellular fatty acid-binding proteins (FABPs) belongs to a multigene family. FABPs are divided into at least three distinct types, namely the hepatic-, intestinal- and cardiac-type. They form 14-15 kDa proteins and are thought to participate in the uptake, intracellular metabolism and/or transport of long-chain fatty acids. They may also be responsible in the modulation of cell growth and proliferation. Fatty acid-binding protein 3 gene contains four exons and its function is to arrest growth of mammary epithelial cells. This gene is a candidate tumor suppressor gene for human breast cancer. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Mar 2016]
General function
Intracellular signaling cascade
Comment
Cellular localization
Cytoplasmic
Comment
Ovarian function
Steroid metabolism, Oocyte maturation
Comment
Fatty Acid Binding Protein 3 And Transzonal Projections Are Involved In Lipid Accumulation During In Vitro Maturation Of Bovine Oocytes. Del Collado M et al. (2017) Oocytes that undergo in vitro maturation (IVM) are metabolically abnormal and accumulate excess lipid content. However, the mechanism of lipid accumulation and the role of cumulus cells in this process are unclear. Recently, it was shown that fatty acid binding proteins (FABPs) performed intra- and extracellular fatty acid transport. We postulated that FABP3 might be responsible for fatty acid transport from cumulus cells to the oocytes via transzonal projections (TZPs) during IVM. Transcript and protein levels of FABP3 were analyzed in both in vivo- and in vitro-matured cumulus-oocyte-complexes and were increased in IVM samples. Further analysis showed increased lipid content in oocytes and cumulus cells in IVM samples compared to in vivo-derived. We therefore speculated that altered traffic of fatty acids via FABP3 during IVM was the mechanism leading to the excess of lipids accumulated within IVM oocytes. Furthermore, we demonstrated an increase in FABP3 levels and lipid content during the first 9 h of IVM, further strengthening the possibility of fatty acid transport via FABP3 and TZPs. Additionally, disruptions of TZPs during IVM decreased lipid accumulation in oocytes. Our results shed light on a possible mechanism involving FABP3 and TZPs that causes excess lipid accumulation in oocytes during IVM.//////////////////
Chandra P. Leo, et al 2001 used
DNA array to analyze changes in preovulatory gene expression in the rat
Ovary. They reported that
the
screening identified a group of candidate genes whose ovarian
expression and gonadotropin regulation was hitherto unknown. The
induction of three of these genes, encoding cutaneous fatty acid-binding
protein, the interleukin-4 receptor alpha chain, and prepronociceptin, was
confirmed and further characterized by Northern blot analysis. In addition,
in situ hybridization analysis showed that hCG administration resulted in
exclusive or predominant expression of all three genes in theca cells.
By contrast, the message for heart FABP was the most highly repressed message
among the 597 genes represented in the array.
Three other genes for FABPs-intestinal FABP, adipocyte FABP, and liver
FABP-were also represented on the array, but the quantification revealed no clear regulation of
the mRNA by hCG.Expression of the cutaneous FABP and heart FABP genes in theca cells of the rat ovary and their contrary
regulation by hCG suggest a differential role for these two FABPs in the preovulatory ovary,
possibly relating to the changes in lipid metabolism accompanying corpus luteum formation.
Expression regulated by
LH
Comment
Ovarian localization
Cumulus, Theca
Comment
Fatty acid synthesis and oxidation in cumulus cells support oocyte maturation in bovine. Sanchez-Lazo L 2014 et al.
Oocyte meiotic maturation requires energy from various substrates including glucose, amino acids and lipids. Mitochondrial fatty acid (FA) beta-oxidation (FAO) in the oocyte is required for meiotic maturation, which is accompanied by differential expression of numerous genes involved in FA metabolism in surrounding cumulus cells (CC) in vivo. The objective was to elucidate components involved in FA metabolism in CC during oocyte maturation. Twenty-seven genes related to lipogenesis, lipolysis, FA transport and FAO were chosen from comparative transcriptome analysis of bovine CC before and after maturation in vivo. Using real time PCR, 22 were significantly up-regulated at different times of in vitro maturation (IVM) in relation to oocyte meiosis progression from germinal vesicle (GV) breakdown to metaphase-II. Proteins FA synthase, acetyl-Co-A carboxylase, carnitine palmitoyltransferase CPT1, perilipin 2 and FA binding protein FABP3 were detected by western blot and immunolocalized to CC and oocyte cytoplasm, with FABP3 concentrated around oocyte chromatin. By mass spectrometry, CC lipid profiling was shown to be different before and after IVM. FAO inhibitors etomoxir and mildronate dose-dependently decreased oocyte maturation rate in vitro. In terms of viability, cumulus enclosed oocytes were more sensitive to etomoxir than denuded oocytes. In CC, etomoxir (150 M) led to down-regulation of lipogenesis genes and up-regulated lipolysis and FAO genes. Moreover, the number of lipid droplets decreased whereas several lipid species were more abundant compared to non-treated CC after IVM. In conclusion, FA metabolism in CC is important to maintain metabolic homeostasis and may influence meiosis progression and survival of enclosed oocytes.
/////////////////////////