The plasma membrane-associated transcription factor NAC091 regulates unfolded protein response in Arabidopsis thaliana.

Adverse environmental stresses may cause the accumulation of unfolded or misfolded proteins in the endoplasmic reticulum (ER), and the unfolded protein response (UPR) pathway is initiated to mitigate the ER stress. Previous studies demonstrate that NAC062, a plasma membrane-associated transcription factor, plays important roles in promoting cell survival under ER stress conditions in Arabidopsis thaliana. In this study, we identified another plasma membrane-associated transcription factor, NAC091 (also known as ANAC091/TIP), as an important UPR mediator. ER stress induces the expression of NAC091, which is mainly dependent on the ER stress regulators bZIP60 and bZIP28. In addition, NAC091 has transcriptional activation activity, and the truncated form of NAC091 devoid of the C-terminal transmembrane domain (TMD) forms a homodimer in the nucleus. Under ER stress conditions, NAC091 relocates from the plasma membrane to the nucleus and regulates the expression of canonical UPR genes involved in cell survival. Further, the loss-of-function mutant of NAC091 confers impaired ER stress tolerance. Together, these results reveal the important role of NAC091 in ER stress response in Arabidopsis, and demonstrate that NAC091 relays the ER stress signal from the plasma membrane to the nucleus to alleviate ER stress and promote cell survival in plants.

[Effect of danshensu and ligustrazine on related genes of myocardial hypertrophy induced by angiotensin II].

OBJECTIVE: To study the effect of Danshensu (DSS) and Ligustrazine (TMZ), the extracts of Chinese herbs for promoting blood circulation, on angiotensin II (Ang II) induced myocardial hypertrophy and its related genes, and to explore the mechanisms of inhibitory effect. METHODS: Adopting one-step method, the total RNA of myocardial cells was extracted by TRIzol reagent. Then the expression of ANP and beta-actin mRNA, as symbol of myocardial cells, were detected by RT-PCR. RESULTS: Molecular biological research showed that Ang II could significantly increase the expression of ANP mRNA in myocardial cells (P < 0.01), which could be significantly inhibited by Losartan (P < 0.01), both DSS and TMZ had the inhibitory effect (P < 0.05). Ang II could increase beta-actin mRNA expression in myocardial cells simultaneously, Losartan, DSS and TMZ could also significantly inhibit it (P < 0.05). CONCLUSION: The effective ingredients of Chinese herbs for promoting blood circulation, DSS and TMZ, have the effect of inhibiting the hyper-expression of ANP and beta-actin induced by Ang II, and preventing myocardial hypertrophy, therefore, it could be used to prevent and treat cardiomegaly.