Background The control of food intake depends, in part, of the action and signaling of hormones, such as insulin in hypothalamic neurons. In obesity, inflammatory cytokines activate protein phosphatases, such as protein tyrosine phosphatase 1B (PTP1B). PTP1B interacts with the insulin receptor (IR) and the insulin receptor substrate (IRS1), inhibiting them in hypothalamus. Other brain regions, ...

Protein kinases are an important class of substrate of the protein phosphatases. We have examined the mechanism of dephosphorylation of the activation segments of the insulin receptor kinase and cyclin-dependent kinase 2 by their respective phosphatases, namely the tyrosine specific phosphatase PTP1B and the dual specificity phosphatase KAP. These studies reveal that PTP1B and KAP utilize contr...

Expression of wild-type protein tyrosine phosphatase (PTP) 1B may act either as a tumor suppressor by dysregulation of protein tyrosine kinases or a tumor promoter through Src dephosphorylation at Y527 in human breast cancer cells. To explore whether mutated PTP1B is involved in human carcinogenesis, we have sequenced PTP1B cDNAs from human tumors and found splice mutations in ~20% of colon and...

Protein tyrosine phosphatases (PTPases) are important targets for the treatment of insulin resistance in patients with type II diabetes and as antibacterial agents. As a result, there is a growing interest in the development of potent and specific inhibitors for these enzymes. This paper describes a series of inhibitors that contain two or three alpha-ketocarboxylic acid groups that are designe...

Redox regulation of protein tyrosine phosphatase 1B (PTP1B) involves oxidative conversion of the active site cysteine thiolate into an electrophilic sulfenyl amide residue. Reduction of the sulfenyl amide by biological thiols regenerates the native cysteine residue. Here we explored fundamental chemical reactions that may enable covalent capture of the sulfenyl amide residue in oxidized PTP1B. ...

Rho GTPases are signal transduction effectors that control cell motility, cell attachment, and cell shape by the control of actin polymerization and tyrosine phosphorylation. To identify cellular targets regulated by Rho GTPases, we screened global protein responses to Rac1, Cdc42, and RhoA activation by two-dimensional gel electrophoresis and mass spectrometry. A total of 22 targets were ident...

Glomerular podocytes are critical for the barrier function of the glomerulus in the kidney and their dysfunction causes protein leakage into the urine (proteinuria). Nephrin is a key podocyte protein, which regulates the actin cytoskeleton via tyrosine phosphorylation of its cytoplasmic domain. Here we report that two protein tyrosine phosphatases, PTP1B and PTP-PEST negatively regulate nephrin...

Protein tyrosine phosphatase 1B (PTP1B) and T-cell protein (TC-PTP) play non-redundant negative regulatory roles in activation, tumor antigen presentation, insulin leptin signaling, are potential targets for several therapeutic applications. Here, we report the development of a highly potent selective small molecule degrader DU-14 both PTP1B TC-PTP. mediated TC-PTP degradation requires target p...

As a therapeutic target, protein tyrosine phosphatase 1B (PTP1B) has received considerable attention for the treatment of diabetes mellitus. A QSAR study using substituted monocyclic and polycyclic thiophene derivatives, recently reported as potent PTP1B inhibitors, was carried out. More than 60 physicochemical descriptors were calculated which underwent rational selection before their use in d...

We used a substrate-trapping technique to search for substrates of protein tyrosine phosphatase (PTP) 1B. A catalytically inactive form of this enzyme forms a stable, phosphotyrosine-dependent complex with epidermal growth factor receptor (EGFR) both in vitro and in cells. PTP1B also interacts with activated platelet-derived growth factor receptor (PDGFR) but not with colony-stimulating factor ...