NAC had an overall inhibitory effect on the UV B induced Tdc and Str transcript levels as well as the catharanthine accumulation. NAC apart from protect ing phosphatases from inactivation is also a potent inhib itor of ROS production. The results shown in Figure 2 as well as Figure 8 indicate that the UV B signaling involves both ROS production and inactivation of phosphatases. Discussion Ivacaftor molecular weight Several studies have demonstrated the involvement of sig nal components, such as receptors, Ca2 influx, medium alkalinization, oxidative burst, and protein kinases and phosphatases in responses to elicitors for enhanced pro duction of secondary metabolites via increased transcrip tion of relevant genes. It has been shown earlier in C. roseus that the abiotic elicitor UV B induces the formation of dimeric TIAs, and Tdc and Str mRNA accumulation.

There is also evidence that nuclear factor GT 1 func tion in the regulation of Tdc gene expression by UV light in C. roseus. However, the UV B signaling pathway that regulates activity of transcription factor GT 1 leading to Tdc gene expression is still obscure. In the present study, we present evidence for involvement of a putative receptor, calcium, reactive oxygen species, Ca2 dependent protein kinase, and a putative MAPK in UV B signaling and transcriptional activation of Tdc and Str genes and catharanthine biosynthesis in C. roseus cells. Based on suramin interference with the binding of sys temin to its cell surface receptor and UV B responses in L. peruvianum cells we used suramin to assess the involvement of a cell surface receptor in UV B induced expression of TIA biosynthetic genes.

The results shown in Figure 1, 2 and 5 show that the UV B induced medium alkalinization, ROS production, CDPK and MBPK activi ties, Tdc and Str gene expression, and accumulation of catharanthine were all inhibited by suramin. Suramin per se is not known to affect medium alkalinization directly but acts via a receptor. This suggested that suramin acts upstream of the afore mentioned UV B induced responses and the UV B induced TIA biosynthesis. The inhibitory effect of suramin on the UV B responses sup ports role of a putative cell surface receptor in UV B signal pathway for the enhancement of Tdc and Str mRNA and catharanthine accumulation in the C. roseus cells. We used a Ca2 chelator.

EGTA, and Ca2 channel blocker, verapamil to investigate the role of Ca2 in UV B induced responses. Both the treatments blocked the UV B induced stimulation of MBPK and CDPK activities and the UV B induced accumulation of Tdc and Str mRNAs, and catha ranthine. Carfilzomib Because EGTA and verapamil are unlikely to enter cells, and verapamil blocks the Ca2 channels local ized in the plasma membrane, our data indicate that the influx of Ca2 from extracellular medium is required for the transduction of the UV B signal, and that UV B may influence the activity of the Ca2 channels.