Transcriptional and post-transcriptional regulation of transmembrane protein 132A.

Transmembrane protein 132A (TMEM132A) was first isolated from rat brain using PCR-selected cDNA subtraction, and it was found to be predominantly expressed in the brain. However, the transcriptional regulation of the TMEM132A gene has not been fully characterized. In this study, we characterized the promoter activity of the 880-bp region upstream of the mouse TMEM132A, identifying several putative sites recognized by transcription factors, which are highly conserved between the mouse and human TMEM132A genes. Using four different mouse cell lines (Neuro2a, NSC-34, NIH3T3, and Raw264.7), we first evaluated the intrinsic levels of TMEM132A mRNA and protein expression. Interestingly, TMEM132A mRNA was expressed in all four cell lines, whereas the protein was negligible in Raw264.7 cells even by transfection of TMEM132A gene. Then, we analyzed the TMEM132A promoter activity using serial deleted constructs, finding it was nearly same pattern in all four cell lines. A mutational analysis of the TMEM132A promoter identified a critical region for its activation just upstream of the transcriptional start site. Finally, we investigated the levels of TMEM132A mRNA and protein after exposure to five different neurotoxic stimuli, including thapsigargin, tunicamycin, serum starvation, homocysteine, and hydrogen peroxide. Treatment with thapsigargin, a calcium modulating agent, markedly attenuated the levels of TMEM132A mRNA and protein in NSC-34 cells. These results give new insight into the mechanisms involved in regulating TMEM132A expression, and suggest that several transcriptional and post-transcriptional pathways regulate TMEM132A expression under developmental and pathophysiological conditions.