Markers of Sternness

Examples

OCT—4, SSEAs, CD133, ABCG2, and Nestin are several commonly used sternness markers. OCT—4 is one of the most commonly used markers for identifying embryonic stem cells. OCT-4 is required for embryonic stem cell self—renewal, to generate more stem cells, and for multiple lineage differentiation, to generate different cells in the body. Several other genes are also related to this property, such as Sox2 and Naong. Stage—specific embryonic [Page 312]antigens (SSEAs) are molecules that regulate cell—cell communication and interaction with intra—cellular structures. There are several SSEA proteins expressed in different tissue at various stages of development in embryonic stem cells and adult stem cells. CD133 is a sugar—attached protein that is expressed on the surface of blood stem cells and several tissue—specific stem cells such as neuron, breast, prostate, and colon stem cells. Recent studies suggest that CD 133 is also expressed in cancer stem cells. ABCG2 (ATP—binding cassette super—family G member 2) is a membrane transporter that is responsible for Hoechst—exclusion side—population stem cells by transporting Hoechst dye out of the stem cell membrane. Nestin is expressed predominantly in neuron stem cells, but its expression is absent in mature neuron.

Identification and Application

Stem cell markers are gene expression products that are uniquely related to stem cells. They are typically proteins or carbohydrates that are specifically expressed in stem cells. These markers are relatively spécifie and are usually expressed at a low level or are not expressed at all in terminal differentiated cells. However, most of the stem cell markers are not expressed exclusively in stem cells: Some of the stem cell markers are also expressed on many other differentiated cells in various tissues, and in tumor stem cells at different levels.

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