Tyrosine-protein phosphatase non-receptor type 11 (PTPN11) also known as protein-tyrosine phosphatase 1D (PTP-1D), Src homology region 2 domain-containing phosphatase-2 (SHP-2), or protein-tyrosine phosphatase 2C (PTP-2C) is an enzyme that in humans is encoded by the PTPN11 gene. PTPN11 is a protein tyrosine phosphatase (PTP) Shp2. [5] [6]
PTPN11 is a member of the protein tyrosine phosphatase (PTP) family. PTPs are known to be signaling molecules that regulate a variety of cellular processes including cell growth, differentiation, mitotic cycle, and oncogenic transformation. This PTP contains two tandem Src homology-2 domains, which function as phospho-tyrosine binding domains and mediate the interaction of this PTP with its substrates. This PTP is widely expressed in most tissues and plays a regulatory role in various cell signaling events that are important for a diversity of cell functions, such as mitogenic activation, metabolic control, transcription regulation, and cell migration. Mutations in this gene are a cause of Noonan syndrome as well as acute myeloid leukemia. [7]
This phosphatase, along with its paralogue, Shp1, possesses a domain structure that consists of two tandem SH2 domains in its N-terminus followed by a protein tyrosine phosphatase (PTP) domain. In the inactive state, the N-terminal SH2 domain binds the PTP domain and blocks access of potential substrates to the active site. Thus, Shp2 is auto-inhibited.
Upon binding to target phospho-tyrosyl residues, the N-terminal SH2 domain is released from the PTP domain, catalytically activating the enzyme by relieving this auto-inhibition.
Missense mutations in the PTPN11 locus are associated with both Noonan syndrome and Leopard syndrome. At least 79 disease-causing mutations in this gene have been discovered. [8]
It has also been associated with Metachondromatosis. [9]
In the case of Noonan syndrome, mutations are broadly distributed throughout the coding region of the gene but all appear to result in hyper-activated, or unregulated mutant forms of the protein. Most of these mutations disrupt the binding interface between the N-SH2 domain and catalytic core necessary for the enzyme to maintain its auto-inhibited conformation. [10]
The mutations that cause Leopard syndrome are restricted regions affecting the catalytic core of the enzyme producing catalytically impaired Shp2 variants. [11] It is currently unclear how mutations that give rise to mutant variants of Shp2 with biochemically opposite characteristics result in similar human genetic syndromes.
Patients with a subset of Noonan syndrome PTPN11 mutations also have a higher prevalence of juvenile myelomonocytic leukemias (JMML). Activating Shp2 mutations have also been detected in neuroblastoma, melanoma, acute myeloid leukemia, breast cancer, lung cancer, colorectal cancer. [12] Recently, a relatively high prevalence of PTPN11 mutations (24%) were detected by next-generation sequencing in a cohort of NPM1-mutated acute myeloid leukemia patients, [13] although the prognostic significance of such associations has not been clarified. These data suggests that Shp2 may be a proto-oncogene. However, it has been reported that PTPN11/Shp2 can act as either tumor promoter or suppressor. [14] In aged mouse model, hepatocyte-specific deletion of PTPN11/Shp2 promotes inflammatory signaling through the STAT3 pathway and hepatic inflammation/necrosis, resulting in regenerative hyperplasia and spontaneous development of tumors. Decreased PTPN11/Shp2 expression was detected in a subfraction of human hepatocellular carcinoma (HCC) specimens. [14] The bacterium Helicobacter pylori has been associated with gastric cancer, and this is thought to be mediated in part by the interaction of its virulence factor CagA with SHP2. [15]
PTPN11 has been shown to interact with
CagA is a protein and virulence factor inserted by Helicobacter pylori into gastric epithelia. Once activated by SRC phosphorylation, CagA binds to SHP2, allosterically activating it. This leads to morphological changes, abnormal mitogenic signals and sustained activity can result in apoptosis of the host cell. Epidemiological studies have shown roles of cagA- positive H. pylori in the development of atrophic gastritis, peptic ulcer disease and gastric carcinoma. [71]
The JAK-STAT signaling pathway is a chain of interactions between proteins in a cell, and is involved in processes such as immunity, cell division, cell death, and tumour formation. The pathway communicates information from chemical signals outside of a cell to the cell nucleus, resulting in the activation of genes through the process of transcription. There are three key parts of JAK-STAT signalling: Janus kinases (JAKs), signal transducer and activator of transcription proteins (STATs), and receptors. Disrupted JAK-STAT signalling may lead to a variety of diseases, such as skin conditions, cancers, and disorders affecting the immune system.
GRB2-associated-binding protein 2 also known as GAB2 is a protein that in humans is encoded by the GAB2 gene.
JAK1 is a human tyrosine kinase protein essential for signaling for certain type I and type II cytokines. It interacts with the common gamma chain (γc) of type I cytokine receptors, to elicit signals from the IL-2 receptor family, the IL-4 receptor family, the gp130 receptor family. It is also important for transducing a signal by type I (IFN-α/β) and type II (IFN-γ) interferons, and members of the IL-10 family via type II cytokine receptors. Jak1 plays a critical role in initiating responses to multiple major cytokine receptor families. Loss of Jak1 is lethal in neonatal mice, possibly due to difficulties suckling. Expression of JAK1 in cancer cells enables individual cells to contract, potentially allowing them to escape their tumor and metastasize to other parts of the body.
Phosphatidylinositol 3-kinase regulatory subunit alpha is an enzyme that in humans is encoded by the PIK3R1 gene.
Tyrosine-protein phosphatase non-receptor type 6, also known as Src homology region 2 domain-containing phosphatase-1 (SHP-1), is an enzyme that in humans is encoded by the PTPN6 gene.
Cbl is a mammalian gene encoding the protein CBL which is an E3 ubiquitin-protein ligase involved in cell signalling and protein ubiquitination. Mutations to this gene have been implicated in a number of human cancers, particularly acute myeloid leukaemia.
RAS p21 protein activator 1 or RasGAP, also known as RASA1, is a 120-kDa cytosolic human protein that provides two principal activities:
GRB2-associated-binding protein 1 is a protein that in humans is encoded by the GAB1 gene.
Protein tyrosine kinase 2 beta is an enzyme that in humans is encoded by the PTK2B gene.
Fibroblast growth factor receptor substrate 2 is a protein that in humans is encoded by the FRS2 gene.
Tyrosine-protein phosphatase non-receptor type 12 is an enzyme that in humans is encoded by the PTPN12 gene.
Receptor-type tyrosine-protein phosphatase alpha is an enzyme that in humans is encoded by the PTPRA gene.
Tyrosine-protein phosphatase non-receptor type 13 is an enzyme that in humans is encoded by the PTPN13 gene.
Receptor-type tyrosine-protein phosphatase F is an enzyme that, in humans, is encoded by the PTPRF gene.
Signal regulatory protein α (SIRPα) is a regulatory membrane glycoprotein from SIRP family expressed mainly by myeloid cells and also by stem cells or neurons.
Protein tyrosine phosphatase non-receptor type 7 is an enzyme that in humans is encoded by the PTPN7 gene.
Protein tyrosine phosphatase receptor-type R is an enzyme that in humans is encoded by the PTPRR gene.
Tyrosine-protein phosphatase non-receptor type 18 is an enzyme that in humans is encoded by the PTPN18 gene.
Tyrosine-protein phosphatase non-receptor type 21 is an enzyme that in humans is encoded by the PTPN21 gene.
A non-receptor tyrosine kinase (nRTK) is a cytosolic enzyme that is responsible for catalysing the transfer of a phosphate group from a nucleoside triphosphate donor, such as ATP, to tyrosine residues in proteins. Non-receptor tyrosine kinases are a subgroup of protein family tyrosine kinases, enzymes that can transfer the phosphate group from ATP to a tyrosine residue of a protein (phosphorylation). These enzymes regulate many cellular functions by switching on or switching off other enzymes in a cell.
and associates transiently with the SH2 domain-containing proteins p85 and SHP2