Bilirubin and Activation of CYP1A1 Expression Under Ultrasound Action

Abstract

Glial cell line-derived neurotrophic factor (GDNF) was first identified as a protein with specific neuro-trophic activity to the dopaminergic neurons in nigra-striatum of brain. Several lines of studies have demonstrated that GDNF plays an important role in the survival and/or differentiation of dopaminergic neurons as well as motor neurons. The signal transduction from GDNF has been known to be GFRa-1 and Ret dependent. The MAP kinase pathway is functional in GDNF-induced some cellular reactions. Although c-jun was found to be phosphorylated following GDNF stimulation in seveval experiments, the downstream genes of c-jun in the case of GDNF stimulation remain unknown.To elucidate the mechanism on GDNF-induced survival of dopaminergic neurons, we examined the states of some genes involved in cell growth, apoptosis and dopamine metastasis. Here we report that tyrosine hydroxylase (TH), the rate limiting enzyme of dopamine biosynthesis, is induced by GDNF in a neuroblastoma cell line, and this induction occurs at a transcriptionallevel. We will show the data that paralleled with GDNF-induced neurite processing, TH messenger RNA induced soon after GDNF treatment and continuously expressed thereafter. The elevated level of TH protein was also observed but with slower time course. The results from promoter analysis showed that the GDNF-responsive DNA sequence in TH promoter is located within the 2.0 kb proximal promoter region, and AP-1 site in this region is quite contributive to promoter activation. DNA binding experiments indicated that a new DNA-protein complex formed in AP-1 site following GDNF stimulation. Our work also evidenced that MAP kinase cascade is the main pathway transducting the signal from GDNF to TH.Further work is undergoing to understand the detail about GDNF-induced TH expression.The expression level of cyclin-dependent kinase inhibitor (CKI) genes, p21 and p16 were determined by a quantitative RT-PCR (QPCR) method in BALB/c mouse liver transplanted with methylcholanthrene-induced fibrosarcoma. Effect of bleomycin administration was studied on these genes. The m R N A of the specific gene was amplified by RT-PCR technique using the specific primers for the gene, the amount of cDNA thus obtained was quantitatively determined by QPCR method. Results indicate that the expression level in p21 and p16 genes 3-5 times increased in tumor-bearing mouse liver than those found in normal liver. Bleomycin induced, in normal mouse liver, a 3 -fold increase in p21 expression level, but it decreased p16 level to one half of the initial level. O n the other hand, tumor-bearing mouse liver showed n o obvious changes in p21 and p16 expression by the stimulation with bleomycin. These results suggest that these genes related to the cell cycle regulation are fully expressed in tumor-bearing animal by unknown mechanisms, and these highly expressed genes would not respond to the stimuli initiated from D N A damage.The need for a fast and convenient protein expression system is ubiquitous. Nearly every property that cha...