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James A Byrne

Publications and source records attributed to James A Byrne.

3 recordsLinked to original sources
PubMed2006

Transcriptional profiling of rhesus monkey embryonic stem cells.

Embryonic stem cells (ESCs) may be able to cure or alleviate the symptoms of various degenerative diseases. However, unresolved issues regarding survival, functionality, and tumor formation mean a prudent approach should be adopted towards advancing ESCs into human clinical trials. The rhesus monkey provides an ideal model organism for developing strategies to prevent immune rejection and test the feasibility, safety, and efficacy of ESC-based medical treatments. Transcriptional profiling of rhesus monkey ESCs provides a foundation for pre-clinical ESC research in this species. In the present study, we used microarray technology, immunocytochemistry, reverse transcription polymerase chain reaction (RT-PCR) and quantitative real-time PCR (qPCR) to characterize and transcriptionally profile rhesus monkey ESCs. We identified 367 stemness gene candidates that were highly (>85%) conserved across five different ESC lines. Rhesus monkey ESC lines maintained a pluripotent undifferentiated state over a wide range of POU5F1 (also known as OCT4) expression levels, and comparisons between rhesus monkey, mouse, and human stemness genes revealed five mammalian stemness genes: CCNB1, GDF3, LEFTB, POU5F1, and NANOG. These five mammalian genes are strongly expressed in rhesus monkey, mouse, and human ESCs, albeit only in the undifferentiated state, and represent the core key mammalian stemness factors.

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PubMed2003

Nuclei of adult mammalian somatic cells are directly reprogrammed to oct-4 stem cell gene expression by amphibian oocytes.

Nuclear reprogramming by the transplantation of somatic cell nuclei to eggs (in second meiotic metaphase) is always followed by a phase of chromosome replication and cell division before new gene expression is seen. To help understand the mechanism of nuclear reprogramming, we have asked whether the nuclei of normal, nontransformed, nondividing, and terminally differentiated mammalian cells can be directly reprogrammed, without DNA replication, by Xenopus oocytes. We find that nuclei of adult mouse thymocytes and of adult human blood lymphocytes, injected into Xenopus oocytes, are induced to extinguish a differentiation marker and to strongly express oct-4, the most diagnostic mammalian stem cell/pluripotency marker. In the course of 2 days at 18 degrees C, the mammalian oct-4 transcripts are spliced to mature mRNA. We conclude that normal mammalian nuclei can be directly reprogrammed by the nucleus (germinal vesicle) of amphibian oocytes to express oct-4 at a rate comparable to that of oct-4 in mouse ES cells. To our knowledge, this is the first demonstration of a stem cell marker being induced in a differentiated adult human cell nucleus. This is an early step toward the long-term aim of developing a procedure for reprogramming readily accessible human adult cells for cell replacement therapy.

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