The regulation of diacylglycerol lipase alpha expression

Debbie Walker, Gareth Williams, Pat Doherty. Kings College London, London, United Kingdom.

The sn1-diacylglycerol lipases (DAGLs) catalyse the hydrolysis of diacylglycerol (DAG) to the endocannabinoid 2-arachidonoylglycerol (2-AG). Two sn1-DAG lipases have been reported, DAGLα and DAGLβ (Bisogno, et al., 2003). The activity of these enzymes is required for axonal growth during development and for retrograde signalling at mature synapses. Their expression patterns correlate with these roles, changing from expression in axons of the embryo to dendrites in the adult. Evidence of a dynamic expression pattern in the subventricular zone (SVZ) of the adult brain and the loss of proliferating cells following the addition of a DAGL inhibitor to the SVZ, suggests that the DAGLs may also have a role in adult neurogenesis.

This study aims to characterise the promoter region of DAGLα in order to investigate the regulation of DAGLα expression. A promoter was predicted by bioinformatic analysis and cloned, such that a luciferase assay could be optimised to study promoter activity. The predicted DAGLα promoter was found to be active in a range of cell types, including Cor-1 neural stem cells in which a 2-fold increase in activity is seen relative to the empty vector (n=4, P<0.05). Deletion analysis has identified core promoter elements required for maximal activity (19-fold increase in activity relative to the empty vector in Cor-1 cells, n=4, P<0.05) and for suppression (7-fold decrease of maximal activity in Cor-1 cells, n=3, P<0.05) of DAGLα transcription. All analysis by Student’s t-test. Conservation between species and transcription factor binding site predictions has enabled the identification of putative regulatory regions. Deletions of these sites have revealed a potential role for transcription factor Sp1 in a neural stem cell-specific regulation of DAGLα expression.

Additionally, levels of DAGLα have been investigated using real-time PCR and the effects of candidate factors on DAGLα expression studied. Together the data provides a starting point for elucidation of the factors involved in regulating DAGLα expression.

Bisogno T. et al, (2003). J Cell Biol 163: 463-8