Microarray Profile of Differentially Expressed Genes in a Monkey Model of Allergic Asthma
The new millennium promised the scientific world to usher in the era of the human genome .The area of stem cell biology has captured both the scientific and international news headlines. The fabulous ability of an embryo to diversify and of certain adult tissues to regenerate throughout life, is a direct result of specialized cells known as stem cells, which are nature’s gift to multicellular organisms. Stem cells are unique cells that have the capacity for self –renewal and are capable of forming many specialized cell types. These stem cells are present in many animal tissues and are important in tissue repair and homeostasis.
Pluripotent stem cells can give rise theoretically to every cell type in the animal body. The different types of mammalian pluripotent stem cells isolated so far are – Embryonal carcinoma cells, Embryonic stem cells, Embryonic germ cells and Adult stem cells besides those present in the placenta and umbilical cord of the fetus. These stem cells could be used to treat a wide variety of human diseases, especially those in which specialized cell types have been lost or disabled. But what is the reality? What genes are responsible for the important properties of the stem cells? How close are we to taking the stem cell-based treatments into the clinic?
In the present study by Ramalho-Satntos et al an effort has been made to answer all of the above questions .The transcriptional profiles of mouse embryonic, neural and hematopoietic stem cells were compared with the aim to define a genetic program for the stem cells .The differentiated cells from the lateral ventricles of the brain and main cell population of the bone marrow were used as controls. Do the various stem cells resemble each other or their differentiated counterparts?
Using the technique of DNA microarrays containing 12000 genes followed by analysis with Affymetrix MAS 4.0software and dChip, transcripts absent in differentiated cells but present in stem cells were identified .7786 genes, 63%of the array were reproducibly detected. Genes enriched in ESCs, NSCs and HSCs were functionally annotated .All previously known stem cell markers were detected in their respective stem cell population suggesting that each of the stem cells are distinct at the transcriptional level.
In addition to the above data, the study also demonstrates that there is a subset of genes (216) commonly enriched to all stem cells. These genes are most likely responsible for the attributes of “ stemness” of the stem cells. Also observed was that stem cells express a significantly high number of expressed sequence tags (genes whose functions are still unknown).
The current study has opened for exploration a vast new terrain of basic biology .The next few years will no doubt bring great advances in understanding stem cells at the molecular levels. Studies like these will help us to manipulate stem cells in vivo in a useful way.
References: -
1. Ramalho-Santos et al. “Stemness”: Transcriptional profiling of embryonic and adult stem cells. Science 298,597-600,2002.
Tags: biology, francis wodie, Indiana State University, wodie
