Apoptosis signal-regulating kinase 1 (ASK1) also known as mitogen-activated protein kinase kinase kinase 5 (MAP3K5) is a member of MAP kinase family and as such a part of

mitogen-activated protein kinase A mitogen-activated protein kinase (MAPK or MAP kinase) is a type of serine/threonine-specific protein kinases involved in directing cellular responses to a diverse array of stimuli, such as mitogens, osmotic stress, heat shock and proinflamma ...

pathway. It activates c-Jun N-terminal kinase (JNK) and

p38 mitogen-activated protein kinases p38 mitogen-activated protein kinases are a class of mitogen-activated protein kinases (MAPKs) that are responsive to stress stimuli, such as cytokines, ultraviolet irradiation, heat shock, and osmotic shock, and are involved in cell diffe ...

in a Raf-independent fashion in response to an array of stresses such as

oxidative stress Oxidative stress reflects an imbalance between the systemic manifestation of reactive oxygen species and a biological system's ability to readily detoxify the reactive intermediates or to repair the resulting damage. Disturbances in the normal ...

, endoplasmic reticulum stress and calcium influx. ASK1 has been found to be involved in cancer, diabetes,

rheumatoid arthritis Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects synovial joint, joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and h ...

, cardiovascular and neurodegenerative diseases. ''MAP3K5'' gene coding for the protein is located on chromosome 6 at locus 6q22.33. and the transcribed protein contains 1,374 amino acids with 11 kinase subdomains. Northern blot analysis shows that MAP3K5 transcript is abundant in human heart and pancreas.

Mechanism of activation

Under nonstress conditions ASK1 is oligomerized (a requirement for its activation) through its C-terminal

coiled-coil A coiled coil is a structural motif in proteins in which two to seven alpha-helices are coiled together like the strands of a rope. ( Dimers and trimers are the most common types.) They have been found in roughly 5-10% of proteins and have a v ...

domain (CCC), but remains in an inactive form by the suppressive effect of reduced thioredoxin ( Trx) and calcium and integrin binding protein 1 (

CIB1 Calcium and integrin-binding protein 1 is a protein that in humans is encoded by the ''CIB1'' gene and is located in Chromosome 15. The protein encoded by this gene is a member of the calcium-binding protein family. The specific function of this ...

). Trx inhibits ASK1 kinase activity by direct binding to its N-terminal coiled-coil domain (NCC). Trx and CIB1 regulate ASK1 activation in a redox- or calcium- sensitive manner, respectively. Both appear to compete with TNF-α receptor-associated factor 2 (TRAF2), an ASK1 activator.

TRAF2 TNF receptor-associated factor 2 is a protein that in humans is encoded by the ''TRAF2'' gene. Function The protein encoded by this gene is a member of the TNF receptor associated factor (TRAF) protein family. TRAF proteins associate with, a ...

and

TRAF6 TRAF6 is a TRAF human protein. Function The protein encoded by this gene is a member of the TNF receptor associated factor (TRAF) protein family. TRAF proteins are associated with, and mediate signal transduction from members of the TNF rece ...

are then recruited to ASK1 to form a larger molecular mass complex. Subsequently, ASK1 forms homo-oligomeric interactions not only through the CCC, but also the NCC, which leads to full activation of ASK1 through autophosphorylation at threonine 845. ASK1 gene transcription can be induced by inflammatory cytokines such as IL-1 and TNF-α through the activation of the NF-kb protein RelA. Interestingly,

TNF-α Tumor necrosis factor (TNF), formerly known as TNF-α, is a chemical messenger produced by the immune system that induces inflammation. TNF is produced primarily by activated macrophages, and induces inflammation by binding to its receptors o ...

is also able to stabilize the ASK1 protein through deubiquitination. Thus, unlike other members of the mitogen-activated protein kinase family, the regulation of ASK1 expression is transcriptional as well as post-transcriptional.

Interactions

ASK1 has been shown to interact with: *

C-Raf RAF proto-oncogene serine/threonine-protein kinase, also known as proto-oncogene c-RAF or simply c-Raf or even Raf-1, is an enzyme that in humans is genetic code, encoded by the ''RAF1'' gene. The c-Raf protein is part of the MAPK/ERK pathway, E ...

, *

CDC25A M-phase inducer phosphatase 1 also known as dual specificity phosphatase Cdc25A is a protein that in humans is encoded by the cell division cycle 25 homolog A (CDC25A) gene. Function CDC25A is a member of the CDC25 family of dual-specificity ...

, * DAXX, * DUSP19, *

EIF2AK2 Protein kinase RNA-activated also known as protein kinase R (PKR), interferon-induced, double-stranded RNA-activated protein kinase, or eukaryotic translation initiation factor 2-alpha kinase 2 (EIF2AK2) is an enzyme that in humans is encoded by ...

, * GADD45B, *

HSPA1A Heat shock 70 kDa protein 1, also termed Hsp72, is a protein that in humans is encoded by the ''HSPA1A'' gene. As a member of the heat shock protein 70 family and a chaperone protein, it facilitates the proper folding of newly translated and m ...

, *

MAP2K6 Dual specificity mitogen-activated protein kinase kinase 6 also known as MAP kinase kinase 6 (MAPKK 6) or MAPK/ERK kinase 6 is an enzyme that in humans is encoded by the ''MAP2K6'' gene, on chromosome 17. Function MAPKK 6 is a member of the ...

, *

MAP3K7 Mitogen-activated protein kinase kinase kinase 7 (MAP3K7), also known as TAK1, is an enzyme that in humans is encoded by the ''MAP3K7'' gene. Structure TAK1 is an evolutionarily conserved kinase in the MAP3 K family and clusters with the tyro ...

and *

MAPK8IP3 C-jun-amino-terminal kinase-interacting protein 3 is an enzyme that in humans is encoded by the ''MAPK8IP3'' gene. The protein encoded by this gene shares similarity with the product of Drosophila syd gene, required for the functional interaction ...

, *

PDCD6 Programmed cell death protein 6 is a protein that in humans is encoded by the ''PDCD6'' gene. This gene encodes a calcium-binding protein belonging to the penta-EF-hand protein family. Calcium binding is important for homodimerization and for con ...

, * PPP5C, * RB1CC1, *

, *

TRAF5 TNF receptor-associated factor 5 is a protein that in humans is encoded by the ''TRAF5'' gene. Function The scaffold protein encoded by this gene is a member of the tumor necrosis factor receptor-associated factor (TRAF) protein family and co ...

, and *

References

External links

* *

Mechanism of activation

Interactions

References

External links

Further reading