NPEPPS | |||||||||||||||||||||||||||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Identifiers | |||||||||||||||||||||||||||||||||||||||||||||||||||
Aliases | NPEPPS , AAP-S, MP100, PSA, aminopeptidase puromycin sensitive | ||||||||||||||||||||||||||||||||||||||||||||||||||
External IDs | OMIM: 606793 MGI: 1101358 HomoloGene: 36199 GeneCards: NPEPPS | ||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||
Wikidata | |||||||||||||||||||||||||||||||||||||||||||||||||||
|
Puromycin-sensitive amino peptidase also known as cytosol alanyl aminopeptidase or alanine aminopeptidase (AAP) (EC 3.4.11.14) is an enzyme that in humans is encoded by the NPEPPS gene. [5] [6] [7] It is used as a biomarker to detect damage to the kidneys, and that may be used to help diagnose certain kidney disorders. It is found at high levels in the urine when there are kidney problems. [8]
This gene encodes the puromycin-sensitive aminopeptidase, a zinc metallopeptidase which hydrolyzes amino acids from the N-terminus of its substrate. The protein has been localized to both the cytoplasm and to cellular membranes. This enzyme degrades enkephalins in the brain, and studies in mouse suggest that it is involved in proteolytic events regulating the cell cycle. [7] It has been identified as a novel modifier of TAU-induced neurodegeneration with neuroprotective effects via direct proteolysis of TAU protein. [9] [10] The loss of NPEPPS function exacerbates neurodegeneration. [11]
The NPEPPS gene is located at chromosome 17q21, consisting of 25 exons and spanning 40 kb.
NPEPPS is a ubiquitous, 100 kDa, Zn2+ metallopeptidase highly expressed in the brain. [12] Two isozymes have been found and they are expressed differently in the nervous system. [13] Glu 309 is one of the active site glutamates, and its mutation could convert the enzyme into an inactive binding protein. [14]
NPEPPS has been proposed to function in a variety of processes, including metabolism of neuropeptidase, regulation of the cell cycle, and hydrolysis of proteasomal products to amino acids. [15] [16] [17] NPEPPS is a major protease to digest SOD1, similar to its role in TAU-induced neurodegeneration. [10] [18] NPEPPS is also reported to play a role in creating and destroying MHC class I-presented peptides and in limiting MHC class I Ag presentation in dendritic cells. [19]
NPEPPS is induced in neurons expressing mutant huntingtin and is critical in preventing the accumulation of polyglutamine in normal cells. It has been reported as the major peptidase digesting polyglutamine sequences in neurodegenerative diseases, such as Huntington's disease. [20] It has been shown that elevation of NPEPPS activity in vivo could effectively block accumulation of hyperphosphorylated TAU protein and thus slow down the disease progression, suggesting increasing NPEPPS activity may be a feasible therapeutic approach to eliminate accumulation of toxic substrates, which are involved in neurodegenerative diseases. [21]
Puromycin is an antibiotic protein synthesis inhibitor which causes premature chain termination during translation.
Choline acetyltransferase is a transferase enzyme responsible for the synthesis of the neurotransmitter acetylcholine. ChAT catalyzes the transfer of an acetyl group from the coenzyme acetyl-CoA to choline, yielding acetylcholine (ACh). ChAT is found in high concentration in cholinergic neurons, both in the central nervous system (CNS) and peripheral nervous system (PNS). As with most nerve terminal proteins, ChAT is produced in the body of the neuron and is transported to the nerve terminal, where its concentration is highest. Presence of ChAT in a nerve cell classifies this cell as a "cholinergic" neuron. In humans, the choline acetyltransferase enzyme is encoded by the CHAT gene.
Tauopathy belongs to a class of neurodegenerative diseases involving the aggregation of tau protein into neurofibrillary or gliofibrillary tangles in the human brain. Tangles are formed by hyperphosphorylation of the microtubule protein known as tau, causing the protein to dissociate from microtubules and form insoluble aggregates. The mechanism of tangle formation is not well understood, and whether tangles are a primary cause of Alzheimer's disease or play a peripheral role is unknown.
A neurodegenerative disease is caused by the progressive loss of structure or function of neurons, in the process known as neurodegeneration. Such neuronal damage may ultimately involve cell death. Neurodegenerative diseases include amyotrophic lateral sclerosis, multiple sclerosis, Parkinson's disease, Alzheimer's disease, Huntington's disease, multiple system atrophy, tauopathies, and prion diseases. Neurodegeneration can be found in the brain at many different levels of neuronal circuitry, ranging from molecular to systemic. Because there is no known way to reverse the progressive degeneration of neurons, these diseases are considered to be incurable; however research has shown that the two major contributing factors to neurodegeneration are oxidative stress and inflammation. Biomedical research has revealed many similarities between these diseases at the subcellular level, including atypical protein assemblies and induced cell death. These similarities suggest that therapeutic advances against one neurodegenerative disease might ameliorate other diseases as well.
ADAMs are a family of single-pass transmembrane and secreted metalloendopeptidases. All ADAMs are characterized by a particular domain organization featuring a pro-domain, a metalloprotease, a disintegrin, a cysteine-rich, an epidermal-growth factor like and a transmembrane domain, as well as a C-terminal cytoplasmic tail. Nonetheless, not all human ADAMs have a functional protease domain, which indicates that their biological function mainly depends on protein–protein interactions. Those ADAMs which are active proteases are classified as sheddases because they cut off or shed extracellular portions of transmembrane proteins. For example, ADAM10 can cut off part of the HER2 receptor, thereby activating it. ADAM genes are found in animals, choanoflagellates, fungi and some groups of green algae. Most green algae and all land plants likely lost ADAM proteins.
Ataxin-1 is a DNA-binding protein which in humans is encoded by the ATXN1 gene.
Superoxide dismutase [Cu-Zn] also known as superoxide dismutase 1 or hSod1 is an enzyme that in humans is encoded by the SOD1 gene, located on chromosome 21. SOD1 is one of three human superoxide dismutases. It is implicated in apoptosis, familial amyotrophic lateral sclerosis and Parkinson's disease.
Ubiquitin is a protein that in humans is encoded by the UBB gene.
Type 1 tumor necrosis factor receptor shedding aminopeptidase regulator, also known as endoplasmic reticulum aminopeptidase 1 (ARTS-1), is a protein which in humans is encoded by the ARTS-1 gene.
Polyglutamine-binding protein 1 (PQBP1) is a protein that in humans is encoded by the PQBP1 gene.
POU domain, class 3, transcription factor 2 is a protein that in humans is encoded by the POU3F2 gene.
Dipeptidyl aminopeptidase-like protein 6 is a protein that in humans is encoded by the DPP6 gene.
Pitrilysin metallopeptidase 1 also known as presequence protease, mitochondrial (PreP) and metalloprotease 1 (MTP-1) is an enzyme that in humans is encoded by the PITRM1 gene. It is also sometimes called metalloprotease 1 (MP1).PreP facilitates proteostasis by utilizing an ~13300-A(3) catalytic chamber to degrade toxic peptides, including mitochondrial presequences and β-amyloid. Deficiency of PreP is found associated with Alzheimer’s disease. Reduced levels of PreP via RNAi mediated knockdown have been shown to lead to defective maturation of the protein Frataxin.
Junctophilin-3 is a protein in humans that is encoded by the JPH3 gene. The gene is approximately 97 kilobases long and is located at position 16q24.2. Junctophilin proteins are associated with the formation of junctional membrane complexes, linking the plasma membrane with the endoplasmic reticulum in excitable cells. Junctophilin-3 is specific to the brain and has an active role in neurons involved in motor coordination and memory.
Disintegrin and metalloproteinase domain-containing protein 23 is a non-catalytic protein that in humans is encoded by the ADAM23 gene. It is a member of the ADAM family of extracellular matrix metalloproteinases.
Cyclin-dependent kinase 5 is a protein, and more specifically an enzyme, that is encoded by the Cdk5 gene. It was discovered 15 years ago, and it is saliently expressed in post-mitotic central nervous system neurons (CNS).
Neurofilament light polypeptide, also known as neurofilament light chain, abbreviated to NF-L or Nfl and with the HGNC name NEFL is a member of the intermediate filament protein family. This protein family consists of over 50 human proteins divided into 5 major classes, the Class I and II keratins, Class III vimentin, GFAP, desmin and the others, the Class IV neurofilaments and the Class V nuclear lamins. There are four major neurofilament subunits, NF-L, NF-M, NF-H and α-internexin. These form heteropolymers which assemble to produce 10nm neurofilaments which are only expressed in neurons where they are major structural proteins, particularly concentrated in large projection axons. Axons are particularly sensitive to mechanical and metabolic compromise and as a result axonal degeneration is a significant problem in many neurological disorders. The detection of neurofilament subunits in CSF and blood has therefore become widely used as a biomarker of ongoing axonal compromise. The NF-L protein is encoded by the NEFL gene. Neurofilament light chain is a biomarker that can be measured with immunoassays in cerebrospinal fluid and plasma and reflects axonal damage in a wide variety of neurological disorders. It is a useful marker for disease monitoring in amyotrophic lateral sclerosis, multiple sclerosis, Alzheimer's disease, and more recently Huntington's disease. It is also promising marker for follow-up of patients with brain tumors. Higher levels of blood or CSF NF-L have been associated with increased mortality, as would be expected as release of this protein reflects ongoing axonal loss. Recent work performed as a collaboration between EnCor Biotechnology Inc. and the University of Florida showed that the NF-L antibodies employed in the most widely used NF-L assays are specific for cleaved forms of NF-L generated by proteolysis induced by cell death. Methods used in different studies for NfL measurement are sandwich enzyme-linked immunosorbent assay (ELISA), electrochemiluminescence, and high-sensitive single molecule array (SIMOA).
Copper chaperone for superoxide dismutase is a metalloprotein that is responsible for the delivery of Cu to superoxide dismutase (SOD1). CCS is a 54kDa protein that is present in mammals and most eukaryotes including yeast. The structure of CCS is composed of three distinct domains that are necessary for its function. Although CCS is important for many organisms, there are CCS independent pathways for SOD1, and many species lack CCS all together, such as C. elegans. In humans the protein is encoded by the CCS gene.
Oxytocinase is a type of enzyme that metabolizes the endogenous neuropeptide, oxytocin. The most well-characterized oxytocinase is leucyl/cystinyl aminopeptidase, which is also an enkephalinase. Other oxytocinases are also known. During pregnancy, oxytocinase plays a role in balancing concentration of oxytocin by degrading the oxytocin produced by the fetus, as production of oxytocin increases with growth of fetus. One study found that concentration level of oxytocinase increased progressively with gestational age until labor, which indicates that pregnancy development can be statistically evaluated by comparing oxytocinase levels.
Michelle Gray is an American neuroscientist and assistant professor of neurology and neurobiology at the University of Alabama Birmingham. Gray is a researcher in the study of the biological basis of Huntington's disease (HD). In her postdoctoral work, she developed a transgenic mouse line, BACHD, that is now used worldwide in the study of HD. Gray's research now focuses on the role of glial cells in HD. In 2020 Gray was named one of the 100 Inspiring Black Scientists in America by Cell Press. She is also a member of the Hereditary Disease Foundation’s scientific board.