This article may be too technical for most readers to understand.(February 2015) |
Sca-1 stands for "Stem cells antigen-1" (official gene symbol: Ly6a). It consist of 18-kDa mouse glycosyl phosphatidylinositol-anchored cell surface protein (GPI-AP) of the LY6 gene family. [1] It is the common biological marker used to identify hematopoietic stem cell (HSC) along with other markers.
Oct-4, also known as POU5F1, is a protein that in humans is encoded by the POU5F1 gene. Oct-4 is a homeodomain transcription factor of the POU family. It is critically involved in the self-renewal of undifferentiated embryonic stem cells. As such, it is frequently used as a marker for undifferentiated cells. Oct-4 expression must be closely regulated; too much or too little will cause differentiation of the cells.
CD34 is a transmembrane phosphoglycoprotein protein encoded by the CD34 gene in humans, mice, rats and other species.
Homeobox protein NANOG(hNanog) is a transcriptional factor that helps embryonic stem cells (ESCs) maintain pluripotency by suppressing cell determination factors. hNanog is encoded in humans by the NANOG gene. Several types of cancer are associated with NANOG.
Platelet endothelial cell adhesion molecule (PECAM-1) also known as cluster of differentiation 31 (CD31) is a protein that in humans is encoded by the PECAM1 gene found on chromosome17q23.3. PECAM-1 plays a key role in removing aged neutrophils from the body.
The CD44 antigen is a cell-surface glycoprotein involved in cell–cell interactions, cell adhesion and migration. In humans, the CD44 antigen is encoded by the CD44 gene on chromosome 11. CD44 has been referred to as HCAM, Pgp-1, Hermes antigen, lymphocyte homing receptor, ECM-III, and HUTCH-1.
Endothelial stem cells (ESCs) are one of three types of stem cells found in bone marrow. They are multipotent, which describes the ability to give rise to many cell types, whereas a pluripotent stem cell can give rise to all types. ESCs have the characteristic properties of a stem cell: self-renewal and differentiation. These parent stem cells, ESCs, give rise to progenitor cells, which are intermediate stem cells that lose potency. Progenitor stem cells are committed to differentiating along a particular cell developmental pathway. ESCs will eventually produce endothelial cells (ECs), which create the thin-walled endothelium that lines the inner surface of blood vessels and lymphatic vessels. The lymphatic vessels include things such as arteries and veins. Endothelial cells can be found throughout the whole vascular system and they also play a vital role in the movement of white blood cells
Thy-1 or CD90 is a 25–37 kDa heavily N-glycosylated, glycophosphatidylinositol (GPI) anchored conserved cell surface protein with a single V-like immunoglobulin domain, originally discovered as a thymocyte antigen. Thy-1 can be used as a marker for a variety of stem cells and for the axonal processes of mature neurons. Structural study of Thy-1 led to the foundation of the Immunoglobulin superfamily, of which it is the smallest member, and led to some of the initial biochemical description and characterization of a vertebrate GPI anchor and also the first demonstration of tissue specific differential glycosylation.
Proto-oncogene c-KIT is the gene encoding the receptor tyrosine kinase protein known as tyrosine-protein kinase KIT, CD117 or mast/stem cell growth factor receptor (SCFR). Multiple transcript variants encoding different isoforms have been found for this gene. KIT was first described by the German biochemist Axel Ullrich in 1987 as the cellular homolog of the feline sarcoma viral oncogene v-kit.
CD133 antigen, also known as prominin-1, is a glycoprotein that in humans is encoded by the PROM1 gene. It is a member of pentaspan transmembrane glycoproteins, which specifically localize to cellular protrusions. When embedded in the cell membrane, the membrane topology of prominin-1 is such that the N-terminus extends into the extracellular space and the C-terminus resides in the intracellular compartment. The protein consists of five transmembrane segments, with the first and second segments and the third and fourth segments connected by intracellular loops while the second and third as well as fourth and fifth transmembrane segments are connected by extracellular loops. While the precise function of CD133 remains unknown, it has been proposed that it acts as an organizer of cell membrane topology.
Integrin α4β1 is an integrin dimer. It is composed of CD49d and CD29. The alpha 4 subunit is 155 kDa, and the beta 1 subunit is 150 kDa.
Cluster of differentiation antigen 135 (CD135) also known as fms like tyrosine kinase 3, receptor-type tyrosine-protein kinase FLT3, or fetal liver kinase-2 (Flk2) is a protein that in humans is encoded by the FLT3 gene. FLT3 is a cytokine receptor which belongs to the receptor tyrosine kinase class III. CD135 is the receptor for the cytokine Flt3 ligand (FLT3L).
Stem cell factor is a cytokine that binds to the c-KIT receptor (CD117). SCF can exist both as a transmembrane protein and a soluble protein. This cytokine plays an important role in hematopoiesis, spermatogenesis, and melanogenesis.
Insulin gene enhancer protein ISL-1 is a protein that in humans is encoded by the ISL1 gene.
Guanine nucleotide-binding protein-like 3, also known as nucleostemin, is a protein that in humans is encoded by the GNL3 gene. It is found within the nucleolus that binds p53. Nucleostemin regulates the cell cycle and affects cell differentiation, decreasing in amount as this differentiation progresses. It is a marker for many stem cells and cancer cells.
CD226, PTA1 or DNAM-1 is a ~65 kDa immunoglobulin-like transmembrane glycoprotein expressed on the surface of natural killer cells, NK T cell, B cells, dendritic cells, hematopoietic precursor cells, platelets, monocytes and T cells.
CUB domain-containing protein 1 (CDCP1) is a protein that in humans is encoded by the CDCP1 gene. CDCP1 has also been designated as CD318 and Trask. Alternatively spliced transcript variants encoding distinct isoforms have been reported.
Rex1 (Zfp-42) is a known marker of pluripotency, and is usually found in undifferentiated embryonic stem cells. In addition to being a marker for pluripotency, its regulation is also critical in maintaining a pluripotent state. As the cells begin to differentiate, Rex1 is severely and abruptly downregulated.
Stem cell markers are genes and their protein products used by scientists to isolate and identify stem cells. Stem cells can also be identified by functional assays. Below is a list of genes/protein products that can be used to identify various types of stem cells, or functional assays that do the same. The initial version of the list below was obtained by mining the PubMed database as described in
A neuronal lineage marker is an endogenous tag that is expressed in different cells along neurogenesis and differentiated cells such as neurons. It allows detection and identification of cells by using different techniques. A neuronal lineage marker can be either DNA, mRNA or RNA expressed in a cell of interest. It can also be a protein tag, as a partial protein, a protein or an epitope that discriminates between different cell types or different states of a common cell. An ideal marker is specific to a given cell type in normal conditions and/or during injury. Cell markers are very valuable tools for examining the function of cells in normal conditions as well as during disease. The discovery of various proteins specific to certain cells led to the production of cell-type-specific antibodies that have been used to identify cells.
Since haematopoietic stem cells cannot be isolated as a pure population, it is not possible to identify them under a microscope. Therefore, there are many techniques to isolate haematopoietic stem cells (HSCs). HSCs can be identified or isolated by the use of flow cytometry where the combination of several different cell surface markers is used to separate the rare HSCs from the surrounding blood cells. HSCs lack expression of mature blood cell markers and are thus, called Lin-. Lack of expression of lineage markers is used in combination with detection of several positive cell-surface markers to isolate HSCs. In addition, HSCs are characterized by their small size and low staining with vital dyes such as rhodamine 123 or Hoechst 33342.