Death receptor 6 (DR6), also known as tumor necrosis factor receptor superfamily member 21 (TNFRSF21), is a

cell surface receptor Cell surface receptors (membrane receptors, transmembrane receptors) are receptors that are embedded in the plasma membrane of cells. They act in cell signaling by receiving (binding to) extracellular molecules. They are specialized integral m ...

of the

tumor necrosis factor receptor The tumor necrosis factor receptor superfamily (TNFRSF) is a protein superfamily of cytokine receptors characterized by the ability to bind tumor necrosis factors (TNFs) via an extracellular cysteine-rich domain. With the exception of nerve grow ...

superfamily which activates the

JNK c-Jun N-terminal kinases (JNKs), were originally identified as kinases that bind and phosphorylate c-Jun on Ser-63 and Ser-73 within its transcriptional activation domain. They belong to the mitogen-activated protein kinase family, and ar ...

and

NF-κB Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) is a protein complex that controls transcription of DNA, cytokine production and cell survival. NF-κB is found in almost all animal cell types and is involved in cellular ...

pathways. It is mostly expressed in the

thymus The thymus is a specialized primary lymphoid organ of the immune system. Within the thymus, thymus cell lymphocytes or ''T cells'' mature. T cells are critical to the adaptive immune system, where the body adapts to specific foreign invaders. ...

spleen The spleen is an organ found in almost all vertebrates. Similar in structure to a large lymph node, it acts primarily as a blood filter. The word spleen comes .

and

white blood cells White blood cells, also called leukocytes or leucocytes, are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. All white blood cells are produced and derived from mult ...

. The Gene for DR6 is 78,450 bases long and is found on the 6th chromosome. This is transcribed into a 655 amino acid chain weighing 71.8 kDa. Post transcriptional modifications of this protein include glycosylation on the asparagines at the 82, 141, 252, 257, 278, and 289 amino acid locations.

Function

The protein encoded by this gene is a member of the

TNF-receptor The tumor necrosis factor receptor superfamily (TNFRSF) is a protein superfamily of cytokine receptors characterized by the ability to bind tumor necrosis factors (TNFs) via an extracellular cysteine-rich domain. With the exception of nerve growth ...

superfamily. This receptor has been shown to activate

and MAPK8/

, and induce cell apoptosis. Through its

death domain Death is the irreversible cessation of all biological functions that sustain an organism. For organisms with a brain, death can also be defined as the irreversible cessation of functioning of the whole brain, including brainstem, and brain ...

, this receptor interacts with

TRADD Tumor necrosis factor receptor type 1-associated DEATH domain protein is a protein that in humans is encoded by the ''TRADD'' gene. TRADD is an adaptor protein. Function The protein encoded by this gene is a death domain containing adaptor m ...

protein, which is known to serve as an adaptor that mediates signal transduction of TNF-receptors. Knockout studies in mice suggested that this gene plays a role in

T helper cell The T helper cells (Th cells), also known as CD4+ cells or CD4-positive cells, are a type of T cell that play an important role in the adaptive immune system. They aid the activity of other immune cells by releasing cytokines. They are consider ...

activation, and may be involved in inflammation and immune regulation. The DR6 is an alpha-helical integral membrane receptor protein that shows evidence that it has something to do with the inhibition of blood vessels forming on tumors which would allow them to grow larger. Death receptor 6 gets a chemical message and starts a signaling pathway that causes apoptosis, also known as cell death, to occur. It is also expressed in endothelial cells. Tumor cells can induce, through exposition of amyloid precursor protein (APP), DR6-mediated endothelial cell

necroptosis Necroptosis is a programmed form of necrosis, or inflammatory cell death. Conventionally, necrosis is associated with unprogrammed cell death resulting from cellular damage or infiltration by pathogens, in contrast to orderly, programmed cell dea ...

allowing tumors metastasis.

Clinical significance

The free serum levels of this DR6 are heightened with anti-cell death factors in patients that have later stage ovarian cancer. DR6 is also thought to be involved in neurodegeneration in the brain that causes Alzheimer's disease as well as signal transduction in stress response and cellular survival. DR6 induces apoptosis when it is over expressed, however the manner in which the death signal is intracellularly transduced is currently unknown. It has been determined that Bax translocation is necessary for the apoptosis triggered by DR6, but through an unknown pathway instead of the traditional pathways of intrinsic versus extrinsic. APP (

amyloid precursor protein Amyloid-beta precursor protein (APP) is an integral membrane protein expressed in many tissues and concentrated in the synapses of neurons. It functions as a cell surface receptor and has been implicated as a regulator of synapse format ...

) is the natural ligand of DR6 and is first cleaved into

Aβ Amyloid beta (Aβ or Abeta) denotes peptides of 36–43 amino acids that are the main component of the amyloid plaques found in the brains of people with Alzheimer's disease. The peptides derive from the amyloid precursor protein (APP), which ...

and N-APP. N-APP is the fragment that interacts with DR6 to trigger axonal degradation in Alzheimer's patients. This pathway is essentially "hi-jacked" in the aging brain.

Function

Clinical significance

References

Further reading