A novel fatty acid response element controls the expression of the flight muscle FABP gene of the desert locust, Schistocerca gregaria

Abstract

In many tissues, fatty acid binding protein (FABP) expression is stimulated by exposure to elevated fatty acid levels. In contrast to the FABP genes expressed in other tissues, the molecular mechanisms that mediate the upregulation of the muscle FABP gene have not been elucidated. We have studied the expression of locust flight muscle FABP, a protein that is highly homologous to the mammalian H-FABPs. A 130-bp promoter fragment of the locust gene, which includes a canonical TATA box and several GC boxes, is sufficient for the transcription of a reporter gene in mammalian L6 myoblasts. Twofold higher expression rates are observed when the promoter contains 280 bp or more of upstream sequence. Treatment of myoblasts with various fatty acids leads to a marked increase of expression in the longer constructs, but not in the minimal promoter. We have identified a 19-bp inverted repeat (2162/2180) as the element responsible for the fatty acid-mediated induction of gene expression. Deletion of this element eliminates the fatty acid response, and gel shift analysis demonstrates specific binding to nuclear proteins from both L6 myoblasts and locust flight muscle cells. This fatty acid response element bears no similarity to any known transcription factor binding site. A similar palindrome was also found in the promoter of the Drosophila melanogaster muscle FABP gene, and in reverse orientation upstream of all mammalian heart FABP genes. Given the structural and functional conservation of muscle FABPs and their genes, it is possible that this fatty acid response element also modulates the expression of the mammalian H-FABP genes.Keywords: fatty acid binding protein; gene regulation; FARE; myoblast; gel-shift analysis.Among the most energy-demanding tasks performed by animals is migratory flight of insects that requires many hours of sustained muscle activity [1]. Fatty acids are the preferred substrates to fuel such work, and the extreme metabolic rates encountered during locust migration demand a very large flux of fatty acids through the muscle cell. These muscles appear to be optimally adapted to safely retrieve, transport and metabolize large amounts of fatty acids [2]. One important factor in these processes is the intracellular fatty acid binding protein (FABP), which binds free fatty acids and thus prevents damage due to a fatty acid overload [3,4]. In previous studies we have demonstrated that the expression of FABP in locust flight muscle not only varies with muscle differentiation, but is also upregulated sharply in response to increased lipid flow. Extended flight and increased lipid delivery to the flight muscle lead to a marked increase in FABP expression [5]. This increase parallels similar effects seen for heart FABP (H-FABP ) genes in mammalian species.In mammalian muscles, H-FABP concentrations generally reflect the rates of fatty acid metabolism, with highest levels found in cardiomyocytes [6]. In vivo and in vitro studies have demonstrated that increased fatty acid delivery or utilization lead to eleva...

A novel fatty acid binding protein produced by teratocytes of the aphid parasitoid Aphidius ervi

“…Cytosolic localization has been reported in the few known FABPs of insects where, for example, they play an important role in flight muscles which utilize FAs as the preferred substrates to fuel flight, a very demanding activity (Haunerland, 1997). Prolonged flight and the associated enhanced lipid delivery to muscles result in a marked increase in FABPs (Chen & Haunerland, 1994), controlled by FA-responsive elements (Wu & Haunerland, 2001;Wu et al, 2002), which prevents potential cell damage due to a FA overload (Glatz et al, 1998;Voger et al, 2000). Insect FABPs have also been isolated from Manduca sexta midguts (Smith et al, 1992), but their role in the regulation of gut physiology, other than the likely protective function, remains unclear (Arrese et al, 2001).…”

Peroxisome proliferator‐activated receptors (PPARS): regulators of gene expression in heart and skeletal muscle

“…This would imply that another (functional) PPRE must be located outside the promoter region investigated, or that alternative transcriptional mechanisms are involved. In this respect, it is interesting to note that another type of fatty acid response element, entirely different from the consensus PPRE sequence, has been identified in FABP genes (Wu & Haunerland 2001). This would suggest that fatty acid responsiveness could also be imparted via pathways not involving PPARs.…”

Differential transcriptional modulation of duplicated fatty acid-binding protein genes by dietary fatty acids in zebrafish (Danio rerio): evidence for subfunctionalization or neofunctionalization of duplicated genes

“…From sequence data, it appears that mammalian iLBP gene-promoters consist of a modular structure similar to many eukaryotic promoters, comprised commonly of a TATA box with proximal and distal regulatory elements [ 20 ]. Currently, our understanding of the regulatory elements that control the expression of the FABP genes is modest and limited primarily to mammals [but see [ 21 - 23 ]]. Based on the zebrafish fabp10 sequence [ 24 ], Her et al ., [ 22 ] cloned its promoter and by functional analysis, identified a 435 bp regulatory element that is sufficient to modulate the liver regional expression in transgenic zebrafish.…”