A mitogen-activated protein 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 proinflammatory cytokines. They regulate cell functions including proliferation, gene expression, differentiation, mitosis, cell survival, and apoptosis.
Mitogen Activated Protein (MAP) kinase kinase kinase is a serine/threonine-specific protein kinase which acts upon MAP kinase kinase. Subsequently, MAP kinase kinase activates MAP kinase. Several types of MAPKKK can exist but are mainly characterized by the MAP kinases they activate. MAPKKKs are stimulated by a large range of stimuli, primarily environmental and intracellular stressors. MAPKKK is responsible for various cell functions such as cell proliferation, cell differentiation, and apoptosis. The duration and intensity of signals determine which pathway ensues. Additionally, the use of protein scaffolds helps to place the MAPKKK in close proximity with its substrate to allow for a reaction. Lastly, because MAPKKK is involved in a series of several pathways, it has been used as a therapeutic target for cancer, amyloidosis, and neurodegenerative diseases. In humans, there are at least 19 genes which encode MAP kinase kinase 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 differentiation, apoptosis and autophagy. Persistent activation of the p38 MAPK pathway in muscle satellite cells due to ageing, impairs muscle regeneration.
Mitogen-activated protein kinase kinase is a dual-specificity kinase enzyme which phosphorylates mitogen-activated protein kinase (MAPK).
Apoptosis signal-regulating kinase 1 (ASK1) also known as mitogen-activated protein kinase 5 (MAP3K5) is a member of MAP kinase family and as such a part of mitogen-activated protein kinase pathway. It activates c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinases in a Raf-independent fashion in response to an array of stresses such as oxidative stress, endoplasmic reticulum stress and calcium influx. ASK1 has been found to be involved in cancer, diabetes, rheumatoid arthritis, cardiovascular and neurodegenerative diseases.
Mitogen-activated protein kinase 14, also called p38-α, is an enzyme that in humans is encoded by the MAPK14 gene.
Mitogen-activated protein kinase kinase kinase 7 (MAP3K7), also known as TAK1, is an enzyme that in humans is encoded by the MAP3K7 gene.
Dual specificity protein phosphatase 1 is an enzyme that in humans is encoded by the DUSP1 gene.
Nuclear factor of activated T-cells 5, also known as NFAT5 and sometimes TonEBP, is a human gene that encodes a transcription factor that regulates the expression of genes involved in the osmotic stress.
Mitogen-activated protein kinase kinase kinase 4 is an enzyme that in humans is encoded by the MAP3K4 gene.
Ribosomal protein S6 kinase alpha-4 is an enzyme that in humans is encoded by the RPS6KA4 gene.
Dual specificity protein phosphatase 10 is an enzyme that in humans is encoded by the DUSP10 gene.
Mitogen-activated protein kinase 11 is an enzyme that in humans is encoded by the MAPK11 gene.
Losmapimod (GW856553X) is an investigational drug being developed by Fulcrum Therapeutics for the treatment of facioscapulohumeral muscular dystrophy (FSHD); a phase III clinical trial is pending approval. Losmapimod selectively inhibits enzymes p38α/β mitogen-activated protein kinases (MAPKs), which are modulators of DUX4 expression and mediators of inflammation.
MAPK phosphatases (MKPs) are the largest class of phosphatases involved in down-regulating Mitogen-activated protein kinases (MAPK) signaling. MAPK signalling pathways regulate multiple features of development and homeostasis. This can involve gene regulation, cell proliferation, programmed cell death and stress responses. MAPK phosphatases are therefore important regulator components of these pathways.
Mitogen-activated protein kinase 13, also known as stress-activated protein kinase 4 (SAPK4), is an enzyme that in humans is encoded by the MAPK13 gene.
Celastrol (tripterine) is a chemical compound isolated from the root extracts of Tripterygium wilfordii and Tripterygium regelii. Celastrol is a pentacyclic nortriterpen quinone and belongs to the family of quinone methides. In mice, celastrol is an NR4A1 agonist that alleviates inflammation and induces autophagy. Also in mice, celastrol increase expression of IL1R1, which is the receptor for the cytokine interleukin-1 (IL-1). IL1R1 knock-out mice exposed to celastrol exhibit no leptin-sensitizing or anti-obesity effect.
The interleukin-1 receptor (IL-1R) associated kinase (IRAK) family plays a crucial role in the protective response to pathogens introduced into the human body by inducing acute inflammation followed by additional adaptive immune responses. IRAKs are essential components of the Interleukin-1 receptor signaling pathway and some Toll-like receptor signaling pathways. Toll-like receptors (TLRs) detect microorganisms by recognizing specific pathogen-associated molecular patterns (PAMPs) and IL-1R family members respond the interleukin-1 (IL-1) family cytokines. These receptors initiate an intracellular signaling cascade through adaptor proteins, primarily, MyD88. This is followed by the activation of IRAKs. TLRs and IL-1R members have a highly conserved amino acid sequence in their cytoplasmic domain called the Toll/Interleukin-1 (TIR) domain. The elicitation of different TLRs/IL-1Rs results in similar signaling cascades due to their homologous TIR motif leading to the activation of mitogen-activated protein kinases (MAPKs) and the IκB kinase (IKK) complex, which initiates a nuclear factor-κB (NF-κB) and AP-1-dependent transcriptional response of pro-inflammatory genes. Understanding the key players and their roles in the TLR/IL-1R pathway is important because the presence of mutations causing the abnormal regulation of Toll/IL-1R signaling leading to a variety of acute inflammatory and autoimmune diseases.
Candidalysin is a cytolytic 31-amino acid α-helical amphipathic peptide toxin secreted by the opportunistic pathogen Candida albicans. This toxin is a fungal example of a classical virulence factor. Hyphal morphogenesis in C. albicans is associated with damage to host epithelial cells; during this process Candidalysin is released and intercalates in host membranes. Candidalysin promotes damage of oral epithelial cells and induces lactate dehydrogenase release and calcium ion influx. It is unique in the fact that it is the first peptide toxin to be identified in any human fungal pathogen.
PH-797804 is a drug which acts as a selective inhibitor of the enzyme p38 mitogen-activated protein kinase. It has antiinflammatory effects and has been researched for the treatment of inflammatory lung conditions such as chronic obstructive pulmonary disease and COVID-19. While it has not been adopted for clinical use, it remains widely used in research.
