CD34

1. 본문

CD34 is a transmembrane phosphoglycoprotein that is found on the surface of various cell types, especially on early hematopoietic (blood-forming) and vascular-associated progenitor cells. Here's a breakdown of what CD34 is and its significance:
What it is:

• Protein Structure: CD34 is a 110 kDa glycosylated transmembrane protein, meaning it's a protein embedded in the cell membrane with attached sugar molecules (glycosylation). It's a single-pass type I membrane protein, indicating its orientation within the cell membrane. It has a mucin-like structure that is heavily glycosylated.
• Gene: The CD34 protein is encoded by the *CD34* gene.
• Family: CD34 belongs to a family of sialomucin proteins.

• Hematopoietic Stem/Progenitor Cells: CD34 is most known as a marker for hematopoietic stem cells (HSCs), which are the precursors to all blood cells. It's present on the most primitive stem cells and its expression gradually decreases as these cells differentiate into more mature blood cell types.
• Endothelial Cells: It is expressed on the endothelial cells of blood vessels (capillaries).
• Bone Marrow Stromal Cells: Found on bone marrow stromal cells, which provide support for blood cell development.
• Embryonic Fibroblasts: Expressed in embryonic fibroblasts.
• Some Nerve Tissue It is also present in some nerve tissue.
• Kidney The kidney is one of the most densely vascular organs and CD34 is used as a marker for the capillaries and blood vessels.

• Cell Adhesion: CD34 is primarily considered an adhesion molecule. It helps cells stick to other cells or to the extracellular matrix. It's known to bind to L-selectin and E-selectin, playing a role in lymphocyte homing (the movement of lymphocytes to specific locations). It may mediate the attachment of hematopoietic stem cells to the bone marrow.
• Possible Role in Early Hematopoiesis: It may play a role in the early stages of blood cell formation. It could act as a scaffold, presenting carbohydrates to selectins for cell binding.
• Other functions: It has also been shown to block the adhesion of other cells such as mast cells, eosinophils and dendritic cells.

• Stem Cell Identification: CD34 is widely used as a marker to identify and isolate hematopoietic stem cells for research and clinical applications, such as bone marrow transplantation.
• CD34 Test: CD34 cell count is used to assess bone marrow's ability to recover.
• Vascular Marker: It serves as a marker for blood vessels and capillaries, helping to visualize them in tissues.
• Neoangiogenesis Marker: CD34 can be a sensitive, albeit non-specific, indicator of neoangiogenesis, which is the formation of new blood vessels.
• Disease Association: The *CD34* gene and the CD34 protein are associated with certain diseases, such as Dermatofibrosarcoma Protuberans.