Isolation and sequence polymorphism of a rat retinoblastoma (RB) cDNA

Inhibition of retinoblastoma mRNA degradation through Poly (A) involved in the neuroprotective effect of berberine against cerebral ischemia

Berberine is one kind of isoquinoline alkaloid with anti-apoptotic effects on the neurons suffering ischemia. To address the explanation for these activities, the berberine-induced cell cycle arrest during neurons suffering ischemia/reperfusion had been studied in the present study. According to the in vitro neurons with oxygen-glucose deprivation and in vivo ICR mice with cerebral ischemia/reperfusion, it was found that berberine could protect the mRNA of retinoblastoma (Rb) from degradation through its function on the poly(A) tail. The prolonged half-life of retinoblastoma 1 (gene of Rb, RB1) mRNA level secures the protein level of retinoblastoma, which facilitates cell cycle arrest of neurons in the process of ischemia/reperfusion and subsequently avoids cells entering in the apoptotic process. The poly(A) tail of RB1 mRNA, as a newly identified target of berberine, could help people focus on the interaction between berberine and mRNA to further understand the biological activities and functions of berberine.

Molecular genetic characterisation of intracerebrally transplanted brain tumours

The aim of the present study was the characterisation of genetic alterations in two different experimental gliomas, induced in rats from the inbred strain BDIX by transplacental ethylnitrosourea with subsequent serial transplantation. The genes investigated have been shown previously to be altered during human glial tumour progression and include the gene for the epidermal growth factor receptor (EGFR), the genes for the cell cycle regulators cyclin dependent kinase 4 (CDK4), cyclinD1 (cycD1), the p16 gene (MTS1/INK4) and the retinoblastoma gene (RB). Using a semi-quantitative PCR-based screening method no gross alterations could be detected in these genes, demonstrating that nitrosourea-induced glial tumours of rats do not harbour those genetic changes which typically arise in human malignant gliomas. Thus, the use of this tumour model for gene therapy trials is questionable.

Stage-specific expression and phosphorylation of retinoblastoma protein (pRb) in the rat seminiferous epithelium

To assess the potential role of retinoblastoma protein (pRb) in the regulation of cell cycle during spermatogenesis, the expression of retinoblastoma (Rb) mRNA and protein, as well as the phosphorylation states of pRb, in the rat seminiferous epithelial cycle, were studied. Two transcripts, 5.4 kb and 3.4 kb long, were detected in total RNA from the adult rat testis and only the 5.4 kb transcript was detected in poly (A)+-RNA from 8, 14 and 23-day old rat testes by Northern hybridization. Polysome analysis revealed that only a small portion of both Rb transcripts could be efficiently translated. By in situ hybridization, Rb mRNA was localized to germ cells from stage V pachytene spermatocytes to step 13 spermatids along the epithelial cycle. pRb immunoreactivity was detected in Sertoli cells and spermatogonia at all stages, as well as in the elongated steps 14-19 spermatids by immunohistochemistry. The amount of pRb and the phosphorylation status varied in a stage-specific manner in Western blots. These results show that pRb is expressed in the rat seminiferous epithelium in a cyclic fashion and suggest that it is involved in the regulation of proliferation of spermatogonia and maintenance of the differentiation status of Sertoli cells and spermatids.

Cloning and characterization of the rat p130, a member of the retinoblastoma gene family

A cDNA clone encoding rat p130, a member of the retinoblastoma (Rb) gene family, was isolated based on the sequence homology of the E1A-binding domain. The 4.87 kb cDNA contained an 1135-amino acid open reading frame with high homologies to the human and mouse p130 and a partial homology to the pRb protein. p130 showed difference in distribution of potential phosphorylation sites from pRb in the N-terminal and the B pocket regions. p130 mRNA was detected in most rat tissues. The p130 gene was mapped to rat chromosome 19p11-13 by fluorescence in situ hybridization.