What is the function of STAT?
STAT proteins are latent cytoplasmic transcription factors activated by various extracellular signaling proteins. On activation, STAT proteins can up-regulate the transcription of various target genes and result in uncontrolled cellular proliferation, anti-apoptotic responses, and angiogenesis.
How does STAT activate transcription?
Once STAT reaches the nucleus, it binds to a consensus DNA-recognition motif called gamma-activated sites (GAS) in the promoter region of cytokine-inducible genes and activates transcription.
What is STAT in JAK-STAT pathway?
The JAK-STAT system consists of three main components: (1) a receptor (green), which penetrates the cell membrane; (2) Janus kinase (JAK) (yellow), which is bound to the receptor, and; (3) Signal Transducer and Activator of Transcription (STAT) (blue), which carries the signal into the nucleus and DNA.
What is the STAT gene?
The STAT3 gene is part of a family known as the STAT genes. These genes provide instructions for making proteins that are part of essential chemical signaling pathways within cells. In the immune system, the STAT3 protein transmits signals for the maturation of immune system cells, especially T cells and B cells.
How many JAKs are there?
four
JAKs are a family of proteins that belong to a category of intracellular non-receptor tyrosine kinases. In mammals, the JAK family contains four members: JAK1, JAK2, JAK3, and TYK2.
Which cells use Jak stat?
JAK/STAT signaling is essential for numerous developmental and homeostatic processes, including hematopoiesis, immune cell development, stem cell maintenance, organismal growth, and mammary gland development (Ghoreschi et al. 2009). Figure 1.
Are STATs transcription factors?
Stats (for signal transducers and activators of transcription) are a family of transcription factors that regulate cell growth and differentiation. Their activity is latent until phosphorylation by receptor-associated kinases.
What does STAT bind to?
Once inside the nucleus, the active STAT dimers bind to the promoters of genes containing the consensus recognition motif (GAS motif-ttcnnngaa) and activate transcription of these genes. STATs can bind DNA as dimers or as N-domain-mediated tetramers.
Which cytokines activate JAK-stat?
Granulocyte Colony Stimulating Factor (G-CSF) and Granulocyte/Macrophage Colony Stimulating Factor (GM-CSF) are among other cytokines that have been linked to JAK/STAT pathway activation. G-CSFR is reported to mainly activate JAK2 and STAT3, and is expressed in several normal and malignant tissue (95).
Which cells use Jak-stat?
What is a STAT dimer?
Upon activation by tyrosine kinases, members of the STAT family of transcription factors form stable dimers that are able to rapidly translocate to the nucleus and bind DNA. Similarly, the Stat1 and Stat3 found in the cytoplasm of unstimulated cells also exhibit a dimeric structure.
What type of receptor is Jak-stat?
cytokine receptors
JAKs are associated with cytokine receptors, which are activated upon stimulation and they phosphorylate STAT proteins, enabling them to be transported to the nucleus. Several regulators, such as PTPs, SOCS and PIAS families have been described to modulate the function of the JAK-STAT pathway.
What is the role of STAT3 in transduction?
Moreover, STAT3 mediates important signal transduction cascades elicited by intracellular proteins such as activated Ras or tyrosine kinase oncoproteins (e.g., Src) [9–14]. Many early studies foreshadowed the multiple and distinct biological roles for STAT3 that are appreciated today.
Why does STAT3 form homodimers?
STAT3 forms homodimers by reciprocal SH2 domain-phosphotyrosine interactions between 2 monomers; this was identified as a key activating mechanism leading to stimulation of STAT3 transcriptional function. STAT3 also undergoes serine phosphorylation at position 727 (S727), a modification that enhances transcriptional activity [15–18].
What is the primary amino acid sequence of STAT3?
The primary amino acid sequence of STAT3 revealed a conserved Src homology 2 (SH2) domain and a C-terminal tyrosine residue (Y705 in mice) that becomes phosphorylated by Jak kinases upon cytokine stimulation, protein tyrosine kinase receptor signaling or intracellular protein tyrosine kinase activation [5, 9].
