Normal human breast epithelial cells were transfected with expression vectors containing the p53 gene mutated at either codon 143, 175, 248 or 273, or by infection with a recombinant retroviral vector containing the p53 gene mutated at codons 143, 175, 248, or 273. The breast epithelial cells were monitored for extension of in vitro lifespan and immortalization. Expression of some, but not all, p53 mutants resulted in an extension of in vitro lifespan.
Retroviral infection of hTERT, the catalytic component of telomerase, into BJ fibroblasts (population doubling 28) resulted in reconstitution of telomerase activity, telomere maintenance, and extension of in vitro lifespan. The hTERT-infected cells also exhibited increased growth rate and colony forming efficiency relative to controls, while remaining contact-inhibited and maintaining a p53-mediated damage response following gamma-irradiation.
Telomere shortening in normal human cells causes replicative senescence, a p53-dependent growth arrest state, which is thought to represent an innate defence against tumour progression. However, although it has been postulated that critical telomere loss generates a 'DNA damage' signal, the signalling pathway(s) that alerts cells to short dysfunctional telomeres remains only partially defined.
Proceedings of the National Academy of Sciences of the United States of America
Tissue engineering holds the promise of replacing damaged or diseased tissues and organs. The use of autologous donor cells is often not feasible because of the limited replicative lifespan of cells, particularly those derived from elderly patients. Proliferative arrest can be overcome by the ectopic expression of telomerase via human telomerase reverse transcriptase (hTERT) gene transfection. To study the efficacy and safety of this potentially valuable technology, we used differentiated vascular smooth muscle cells (SMC) and vascular tissue engineering as a model system.
The telomerase ribonucleoprotein is a promising target for cancer therapy, as it is highly active in many human malignancies. A novel telomerase targeting approach combines short interfering RNA (siRNA) knockdown of endogenous human telomerase RNA (hTer) with expression of a mutant-template hTer (MT-hTer). Such combination MT-hTer/siRNA constructs induce a rapid DNA damage response, telomere uncapping, and inhibition of cell proliferation in a variety of human cancer cell lines.
Retroviral vectors are versatile gene transfer vehicles widely used in basic research and gene therapy. Mutation of retroviral integrase converts these vectors into transient, integration-deficient gene delivery vehicles associated with a high degree of biosafety. We explored the option to use integration-deficient retroviral vectors to achieve transient ectopic expression of transcription factors, which is considered an important tool for induced cell fate conversion.
Yakugaku Zasshi: Journal of the Pharmaceutical Society of Japan
The chemical constituents of medicinal plants which have been used in Ayurvedic and Tibetan system of medicines in Nepal were examined. From 21 species consisting of 13 genera of the plants, 121 new compounds, whose structures are shown in Charts (1 to 13), were isolated mainly in our laboratory. Some of the compounds and their related ones showed several biological activities.
Prenatal transplantation of genetically engineered mesenchymal stem cells (MSCs) might benefit prevention or treatment of early-onset genetic disorders due to the cells' intrinsic regenerative potential plus the acquired advantage from therapeutic transgene expression. However, a thorough assessment of the safety, accessibility, and behavior of these MSCs in the fetal environment using appropriate animal models is required before we can advance toward a clinical application.