Molecular biology of human renin and its gene

The Potential Role of CERS1 in Autophagy Through PI3K/AKT Signaling Pathway in Hypophysoma

To explore the role and mechanism of CERS1 in hypophysoma and investigate whether CERS1 overexpression can change the autophagy process of hypophysoma, and then to explore whether CERS1’s effect was regulated by the PI3K/AKT signaling pathway. Western blot and RT-PCR were used to analyze the expression or mRNA level of CERS1 at different tissues or cell lines. Afterwards, the occurrence and development of hypophysoma in vivo and in vitro, respectively, was observed by using CERS1 overexpression by lentivirus. Finally, MK-2206 and LY294002 were applied to discuss whether the role of CERS1 was regulated by the PI3K/AKT signaling pathway. Results show that the CERS1 expression and mRNA level in tumor or AtT-20 cells were decreased. CERS1 over-expressed by lentivirus could inhibit hypophysoma development in vivo and in vitro by reducing tumor volume and weight, weakening tumor proliferation and invasion, and enhancing apoptosis. In addition, shCERS1 could reverse the process. The above results indicate that CERS1 is possibly able to enhance autophagy in hypophysoma through the PI3K/AKT signaling pathway.

In vivo identification of a negative regulatory element in the mouse renin gene using direct gene transfer

DBA/2J mouse contains two renin gene loci (Ren1d and Ren2d). Ren2d but not Ren1d is expressed in submandibular gland (SMG) while both are expressed in the kidney. Based on vitro studies, we have postulated that a negative regulatory element (NRE) in the renin gene promoter is involved in its tissue-specific expression. In this study, we examined the molecular mechanism at the in vivo level using direct gene transfer. Fragments of the Ren1d or Ren2d promoter were fused to a chloramphenicol acetyltransferase (CAT) gene expression vector. These constructs complexed in fusogenic liposomes were injected directly into the mouse SMG or intraarterially into the mouse kidney via the renal artery. The vector containing the CAT exhibited readily detectable in vivo expressions in both SMG and kidney. In the SMG, Ren1d fragment containing the NRE abolished CAT expression while deletion of the NRE restored CAT expression. The homologous fragment from the Ren2d promoter did not inhibit CAT expression while deletion of the 150-bp insertion resulted in the inhibition. Cotransfection of Ren1d construct with Ren1d-NRE oligonucleotides as transcriptional factor decoy restored CAT expression. Contrary to the SMG, transfection with Ren1d fragment-CAT construct or Ren2d fragment-CAT construct into the kidney resulted in similar levels of CAT expression. Interestingly, human c-myc NRE oligonucleotides which share homology with Ren1d-NRE competed effectively with these oligonucleotides for the regulation of Ren1d gene expression in vivo. This NRE sequence is also homologous to silencer elements found in multiple mammalian genes, suggesting the presence of a family of NRE/NRE binding proteins regulating expression of diverse genes.