Multiple liver-specific factors bind to a 64-bp element and activate apo(a) gene.
The high plasma levels of lipoprotein(a) [Lp(a)] are associated with atherosclerosis. The apo(a) gene is responsible for the variance of Lp(a) concentration and its expression is liver-specific. By 5'-deletion analysis, we, in a luciferase gene reporter assay, have identified a 64-bp AT-rich region of upstream apo(a) gene (-703 to -640) that binds to multiple liver-specific factors. The 64 bp cis-element contained three dyad symmetry elements (DSEs) that are crucial for synergistic binding to the factors. We have demonstrated that both DSE-2 and -3 together are responsible for factor binding in vitro, and for gene activation in liver cells. Further, we have purified one of the UV cross-linked DNA-protein complexes to homogeneity by streptavidin magnetic bead chromatography. The identification of a further upstream negative regulatory region (-1432 to -704) led us to predict that as yet unidentified transcriptional repressor(s) might also repress apo(a) gene transcription.
Handa
Vikas
V
Centre for Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India.
Mahboob-ul-hussain
Pati
Nirupma
N
Pati
Uttam
U
ul-Hussain
Mehboob
M
D020856:AT Rich Sequence; D001054:Apolipoproteins A / Q000235:genetics*; D001483:Base Sequence; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008099:Liver / Q000378:metabolism*; D008156:Luciferases / Q000032:analysis; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D020218:Response Elements; D017384:Sequence Deletion; D013539:Simian virus 40 / Q000235:genetics; D019809:Streptavidin / Q000737:chemistry; D015534:Trans-Activators / Q000302:isolation & purification / Q000378:metabolism*; D015533:Transcriptional Activation
D001054:Apolipoproteins A; D004268:DNA-Binding Proteins; D015534:Trans-Activators; D019809:Streptavidin; D008156:Luciferases