Stem Cells

Caspase 9 (also termed ICE-LAP6, Mch6, Apaf-3) is a member of cysteine protease family of caspases and is encoded by the CASP9 gene in humans. Caspase-9 is involved in mitochondrial apoptosis pathway and is an initiator caspase.

SOX2 is a transcription factor that is expressed by self-renewing and multipotent stem cells of the embryonic neuroepithelium. Sox-2 was found to be expressed by dividing neural progenitor cells. Constitutive expression of SOX2 has also been shown to inhibit neuronal differentiation and results in the maintenance of progenitor characteristics.

Extracellular Signal-Regulated Kinases (ERK) also known as the Mitogen-activated Protein Kinase (MAPK), MAPK/ERK proteins are a family of protein-serine/threonine kinases that are activated via the phosphorylation of tyrosine. MAPK/ERK are activated by diverse mechanisms.

Transforming growth factor beta (TGF beta) signaling along with its family members have been implicated in development and maintenance of various organs. Stem cells are important contributors to this process and are characterized by their ability to self-renew and to generate differentiated cells of a particular tissue. Stem cells can be classified into embryonic and somatic stem cells.

The jumonji (JMJ) gene, obtained by a gene trap strategy, is essential for embryogenesis and is suggested to play important roles in cell growth during development. The amino acid sequence of the JMJ protein includes a nuclear localization signal and a DNA binding motif called the AT-rich interactive domain (ARID). Unlike the other members of the JARID family of proteins, JARID2 has a long N-terminal moiety devoid of characterized domains.

Jumonji domain-containing protein 3 (JMJD3), identified as H3K27me3 demethylase, controls the expression of key regulators and markers of neurogenesis, and is required for commitment to the neural lineage. Nevertheless, the precise molecular targets of JMJD3 remain largely uncharacterized. The regulation of JMJD3 appears to be highly gene- and context- specific, suggesting interplay with specific molecules to promote fine-tuning more than the on/off alternation of methylation status.

Beclin 1 is the mammalian orthologue of the yeast Apg6/Vps30 gene. Beclin 1 can complement the defect in autophagy present in apg6 yeast strains and stimulate autophagy when overexpressed in mammalian cells (1) and can bind to Bcl2, an important regulator of apoptosis (2) suggesting a role in two fundamentally important cellular pathways: autophagy and apoptosis.

The polycomb group (PcG) protein, enhancer of zeste homolog 2 (EZH2) is a methyl-transferase that plays a key role in transcriptional gene repression. EZH2 is frequently overexpressed in several malignant tumors, and is often associated with advanced disease stage in many solid tumors.

EGF (epidermal growth factor) stimulates differentiation, proliferation and cell growth by binding to its receptor, EGFR. EGF was first discovered in the mouse submandibular gland in 1986 by Stanley Cohen of Vanderbilt University, leading to a Nobel Prize in Physiology and Medicine. Since then, EGF has been found in many tissues of the human body (including urine, saliva, plasma, milk, macrophages and platelets) and has been the subject of intense study in many areas of clinical research due to its many abilities.

Nucleolin is a multifunctional phosphoprotein ubiquitously distributed in the nucleolus, nucleus and cytoplasm of the cell. Nucleolin has a bipartite nuclear localization signal sequence and is conserved across the species. Nucleolin levels are expressed in abundance in exponentially growing cells and it regulates various aspects of DNA and RNA metabolism, chromatin structure, rDNA transcription, rRNA maturation, cytokinesis, nucleogenesis, cell proliferation and growth (1).