CD133

CD133

CD133, also known as Prominin-1, is a transmembrane glycoprotein that is encoded by the PROM1 gene in humans. It is a well-known marker for identifying and isolating stem cells, particularly in the context of cancer research and regenerative medicine. CD133 is expressed on the surface of various stem and progenitor cells, including hematopoietic stem cells, neural stem cells, and cancer stem cells.

Structure and Function

CD133 is a pentaspan transmembrane protein, meaning it spans the cell membrane five times. It is characterized by its unique structure, which includes an extracellular N-terminus, five transmembrane domains, and two large extracellular loops. The protein is heavily glycosylated, which is important for its function and stability.

The primary function of CD133 is not fully understood, but it is believed to play a role in maintaining stem cell properties, such as self-renewal and differentiation. CD133 is also involved in the organization of plasma membrane protrusions and may participate in cell signaling pathways that regulate cell growth and survival.

Clinical Significance

CD133 is widely used as a marker to identify and isolate stem cells from various tissues. In cancer research, CD133 is often used to identify cancer stem cells, which are a subpopulation of cancer cells thought to be responsible for tumor initiation, progression, and resistance to therapy. The presence of CD133-positive cells in tumors has been associated with poor prognosis in several types of cancer, including glioblastoma, colorectal cancer, and liver cancer.

In regenerative medicine, CD133-positive cells have been explored for their potential to regenerate damaged tissues. For example, CD133-positive cells derived from bone marrow have been investigated for their ability to repair cardiac tissue after myocardial infarction.

Research and Applications

Research on CD133 has expanded our understanding of stem cell biology and cancer. Techniques such as flow cytometry and magnetic-activated cell sorting (MACS) are commonly used to isolate CD133-positive cells for further study. These cells are then used in various applications, including:

• Cancer Research: Studying the role of CD133-positive cancer stem cells in tumorigenesis and therapy resistance.
• Regenerative Medicine: Exploring the potential of CD133-positive stem cells in tissue engineering and regenerative therapies.
• Drug Development: Screening for compounds that target CD133-positive cells to develop more effective cancer treatments.

Controversies and Challenges

Despite its widespread use, the role of CD133 as a universal stem cell marker is debated. Some studies have shown that CD133 expression can be lost during cell differentiation, while others have reported CD133-negative cells with stem cell properties. Additionally, the expression of CD133 can vary between different types of tissues and tumors, complicating its use as a reliable marker.

Also see

• Stem cell marker
• Cancer stem cell
• Regenerative medicine
• Flow cytometry
• Glycoprotein

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