Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.26.9 (ribonuclease)
 6,589 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Androgen insensitivity is an X-linked disorder of sexual differentiation resulting from mutations in the androgen receptor (AR) gene. In this paper, we report the clinical phenotype and molecular analysis of two siblings with severe partial androgen insensitivity due to a novel mutation in the ligand-binding domain of the AR gene. Binding studies using cultured genital skin fibroblasts demonstrated reduced AR affinity and binding capacity. Nucleotide sequence analysis of the AR gene of both siblings revealed a point mutation causing a glycine to arginine amino acid substitution at position 907 within a conserved region of the ligand-binding domain. A silent guanine to adenine substitution was also identified in the protein-coding region of exon 1. Using an expression vector in which the identified mutation was recreated by site-directed mutagenesis, the mutant receptor was found to have a reduced binding affinity (Kd = 3.06 nmol/L) for mibolerone compared with that of normal AR (Kd = 1.71 nmol/L) when expressed in COS-7 cells. In cotransfection experiments using CV-1 cells and a mouse mammary tumor virus-chloramphenicol acetyltransferase reporter system, the concentration of dihydrotestosterone required to induce half-maximal chloramphenicol acetyltransferase gene expression was 50-fold higher in cells transfected with the mutant AR complementary DNA than in cells transfected with normal AR complementary DNA. AR messenger ribonucleic acid levels in genital skin fibroblasts determined by both competitive PCR amplification and ribonuclease protection assay were decreased compared with normal values. Our studies demonstrate the importance of this region of the AR gene in normal AR function and AR gene expression.
 ...
PMID:Partial androgen insensitivity caused by an androgen receptor mutation at amino acid 907 (Gly-->Arg) that results in decreased ligand binding affinity and reduced androgen receptor messenger ribonucleic acid levels. 855 Jul 58

Androgen receptor (AR) plays a key role in cell growth both in the normal prostate and in prostate cancer. Androgen ablation and prolonged antiandrogen therapy can give rise to AR-dependent prostate tumors, which nonetheless can grow in the androgen-deprived milieu. Here we describe the ribozyme approach to selectively degrading the AR mRNA and thereby inhibiting AR function. A trans-acting hammerhead ribozyme was designed to cleave the rat AR mRNA at the position +1827/ 1828, a region predicted to be minimally involved in generating stable secondary structures. Using AR mRNA fragments as substrates, it was established that this ribozyme can specifically cleave the RNA target in a sequence-specific manner. Kinetic experiments determined a Km for the substrate of 77 nM and a kcat/Km value of 1.8 x 10(7) M(-1) x min(-1), suggesting a catalytic efficiency similar to that of protein enzymes such as the relatively nonspecific ribonuclease A and a sequence-specific endonuclease EcoRI. Transient cotransfections of prostate-derived PC3 cells with three plasmids, an AR-inducible chloramphenicol acetyltransferase (CAT) reporter, an AR expression vector, and a ribozyme expression vector, showed that the ribozyme was capable of reducing the functional activity of AR. At an equimolar ratio of the AR expression plasmid to ribozyme expression plasmid, androgen-inducible CAT activity was inhibited 70%. Similar extents of inhibition were also observed at the cellular mRNA level using ribonuclease protection assays, indicating that the ribozyme functioned as an AR mRNA cleaving enzyme in cellulo. Immunocytochemical examination revealed a decline of AR immunoreactivity in ribozyme-transfected cells. In addition, no morphologically detectable cellular abnormalities were associated with ribozyme expression, indicating the absence of deleterious side effects. These results offer a new avenue for the control of AR function and cell growth, especially in the case of androgen-resistant, but AR-dependent, prostate cancer cells.
 ...
PMID:Catalytic cleavage of the androgen receptor messenger RNA and functional inhibition of androgen receptor activity by a hammerhead ribozyme. 977 79

Genes that are regulated by androgens in the human prostate are believed to play an essential role in prostate physiology and they may also be involved in the proliferative response of prostate cancer cells to androgens. We used a cDNA subtraction approach to identify novel androgen-regulated transcripts in LNCaP cells that were exposed to 0.1 nM R1881 for 24 h. We report here that SPAK, a recently identified STE20/SPS1-related kinase that modulates p38 MAP kinase activity, exhibited increased expression in androgen-treated LNCaP cells. Androgen regulation of SPAK was both dose- and time-dependent. R1881-induced SPAK expression was completely abrogated by the antiandrogen casodex and by actinomycin D indicating that androgen induction of SPAK requires the androgen receptor and transcription. Cycloheximide caused a partial inhibition of R1881-induced SPAK expression which suggests that androgen induction of SPAK expression may require synthesis of additional proteins. Northern blot and ribonuclease protection assays demonstrated that SPAK is expressed at high levels in normal human testes and prostate, as well as in a number of breast and prostate cancer cell lines. These results identify SPAK, a member of a key cell signalling pathway, as an androgen-responsive gene in LNCaP cells. We hypothesize that SPAK may mediate androgen action in the normal and cancerous prostate gland.
 ...
PMID:Androgens induce expression of SPAK, a STE20/SPS1-related kinase, in LNCaP human prostate cancer cells. 1151 53