Receptor Protein Tyrosine Phosphatase Research Articles

An in-line method for high-throughput screening of protein tyrosine phosphatase receptor type O inhibitors by capillary electrophoresis based on electrophoretically mediated microanalysis

Protein tyrosine phosphatase receptor type O (PTPRO) plays an important role in inflammation-related pathways and has become an emerging drug target. In this study, we developed an in-line capillary electrophoresis (CE) method for the investigation of the enzymatic activity of PTPRO, which was based on electrophoretically mediated microanalysis (EMMA). After a thorough method validation of the optimized conditions, this protocol was successfully employed to determine the kinetics of PTPRO as well as the half-maximal inhibitory concentration (IC50) of two typical PTPRO inhibitors. The final results were consistent with the values obtained through classical ultraviolet–visible (UV–vis) spectrophotometry. Our new method exhibited improved accuracy and reduced consumption, avoiding the disadvantages of traditional methods. This work provides a new strategy for PTPRO enzyme kinetic studies as well as inhibitory activity determination through capillary electrophoresis for the first time.

Protein tyrosine phosphatase receptor kappa regulates glycolysis, lipid metabolism and promotes hepatocyte reprogramming in obesity

Protein tyrosine phosphatase receptor kappa regulates glycolysis, lipid metabolism and promotes hepatocyte reprogramming in obesity

PTPRC Inhibits Ferroptosis of Osteosarcoma Cells via Blocking TFEB/FTH1 Signaling.

Protein tyrosine phosphatase receptor type C (PTPRC) is reported to function as an oncogenic role in various cancer. However, the studies on the roles of PTPRC in osteosarcoma (OS) are limited. This study aimed to explore the potentials of PTPRC in OS. mRNA levels were detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Protein expression was detected by western blot. Lysosome biogenesis was determined using immunofluorescence. The binding sites of transcription factor EB (TFEB) on the promoter of ferritin heavy chain 1 (FTH1) were predicted by the online dataset JASPAR and confirmed by luciferase and chromatin immunoprecipitation (ChIP) assays. Cell death was determined using propidium iodide (PI) and TdT-mediated dUTP nick-end labeling (TUNEL) staining. The results showed that PTPRC was significantly overexpressed in OS tissues and cells. PTPRC knockdown promoted the phosphorylation and nuclear translocation of TFEB. Moreover, PTPRC knockdown markedly promoted lysosome biogenesis and the accumulation of ferrous ion (Fe2+), whereas decreased the release of glutathione (GSH). Besides, PTPRC knockdown significantly promoted autophagy and downregulated mRNA expression of FTH1 and ferritin light chain (FTL). Additionally, TFEB transcriptionally inactivated FTH1. PTPRC knockdown significantly promoted the ferroptosis of OS cells, which was markedly alleviated by TFEB shRNA. Taken together, PTPRC knockdown-mediated TFEB phosphorylation and translocation dramatically promoted lysosome biogenesis, ferritinophagy, as well as the ferroptosis of OS cells via regulating FTH1/FTL signaling. Therefore, PTPRC/TFEB/FTH1 signaling may be a potential target for OS.

Integrated bioinformatics analysis and network pharmacology to explore the potential mechanism of Patrinia heterophylla Bunge against acute promyelocytic leukemia.

Current treatment with arsenic trioxide and all-trans retinoic acid has greatly improved the therapeutic efficacy and prognosis of acute promyelocytic leukemia (APL), but may cause numerous adverse effects. Patrinia heterophylla Bunge (PHEB), commonly known as "Mu-Tou-Hui" in China, is effective in treating leukemia. However, no studies have reported the use of PHEB for APL treatment. In this study, we aimed to investigate the potential anticancer mechanism of PHEB against APL. Public databases were used to search for bioactive compounds in PHEB, their potential targets, differentially expressed genes associated with APL, and therapeutic targets for APL. The core targets and signaling pathways of PHEB against APL were identified by the protein-protein interaction network, Kaplan-Meier curves, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathway enrichment, and compound-target-pathway network analysis. Molecular docking was performed to predict the binding activity between the most active compounds and the key targets. Quercetin and 2 other active components of PHEB may exert anti-APL effects through proteoglycans in cancer, estrogen signaling, and acute myeloid leukemia pathways. We also identified 6 core targets of the bioactive compounds of PHEB, including protein tyrosine phosphatase receptor type C, proto-oncogene tyrosine-protein kinase Src, mitogen-activated protein kinase phosphatase 3 (MAPK3), matrix metalloproteinase-9, vascular endothelial growth factor receptor-2, and myeloperoxidase, most of which were validated to improve the 5-year survival of patients. Molecular docking results showed that the active compound bound well to key targets. The results not only predict the active ingredients and potential molecular mechanisms of PHEB against APL, but also help to guide further investigation into the anti-APL application of PHEB.

ACGH Analysis Reveals Novel Mutations Associated with Congenital Diaphragmatic Hernia Plus (CDH+).

Congenital diaphragmatic hernia (CDH) is a major birth anomaly that often occurs with additional non-hernia-related malformations, and is then referred to as CDH+. While the impact of genetic alterations does not play a major role in isolated CDH, patients with CDH+ display mutations that are usually determined via array-based comparative genomic hybridization (aCGH). We analyzed 43 patients with CDH+ between 2012 and 2021 to identify novel specific mutations via aCGH associated with CDH+ and its outcome. Deletions (n = 32) and duplications (n = 29) classified as either pathological or variants of unknown significance (VUS) could be detected. We determined a heterozygous deletion of approximately 3.75 Mb located at 8p23.1 involving several genes including GATA4, NEIL2, SOX7, and MSRA, which was consequently evaluated as pathological. Another heterozygous deletion within the region of 9p23 (9,972,017-10,034,230 kb) encompassing the Protein Tyrosine Phosphatase Receptor Type Delta gene (PTPRD) was identified in 2 patients. This work expands the knowledge of genetic alterations associated with CDH+ and proposes two novel candidate genes discovered via aCGH.

Identification of immune microenvironment changes, immune-related pathways and genes in male androgenetic alopecia.

Although androgenetic alopecia (AGA) is classified as a non-inflammatory alopecia, histological evidence of microinflammation has long been recognized. However, changes in the immune microenvironment, immune-related pathways and the expression of immune-related genes (IRGs) involved in AGA remain unclear. The microarray gene expression data (GSE36169) from patients with male AGA were analyzed. gene set enrichment analysis (GSEA) among statistically changed genes was done. Kyoto Encyclopedia of Genes and Genomes and Gene Ontology analyses among differentially expressed genes were performed. differentially expressed genes were screened to identify IRGs based on the ImmPort database. The cytohubba-MCC plugin of Cytoscape was applied to screen hub immune genes. The infiltration levels of 28 immune cells were quantified adopting single-sample GSEA (ssGSEA) algorithm. The microarray gene expression data (GSE90594) of male AGA was analyzed to validate hub IRGs genes and differential infiltrated immune cells. The ssGSEA revealed γδT cell, central memory CD8+ T cell, mast cell, immature B cell, activated CD8+ T cell, effector memory CD4+ T cell, eosinophil and neutrophil were significantly increased infiltration in the bald scalp. GSEA showed statistically changed genes were most enriched in immune related pathways, including innate immune system, adaptive immune system, cytokine signaling, interferon-γ signaling, interferon signaling and interleukins signaling. The 4 hub IRGs, including matrix metallopeptidase 9, protein tyrosine phosphatase receptor type C, bone morphogenetic protein 2, and thrombospondin 1, were enriched in the pathways of allograft rejection, coagulation and interferon-γ response. In summary, we proposed that the increase in γδ T cells, central memory CD8+ T cells, activated CD8+ T cell as well as the infiltration of mast cells contributed to immune microenvironment changes in male AGA. The 4 hub IRGs may be involved in the development and progression of hair loss in male AGA through interferon-γ signal pathways.

Promoting the activity of a receptor tyrosine phosphatase with a novel pH-responsive transmembrane agonist inhibits cancer-associated phenotypes.

Cell signaling by receptor protein tyrosine kinases (RTKs) is tightly controlled by the counterbalancing actions of receptor protein tyrosine phosphatases (RPTPs). Due to their role in attenuating the signal-initiating potency of RTKs, RPTPs have long been viewed as therapeutic targets. However, the development of activators of RPTPs has remained limited. We previously reported that the homodimerization of a representative member of the RPTP family (protein tyrosine phosphatase receptor J or PTPRJ) is regulated by specific transmembrane (TM) residues. Disrupting this interaction by single point mutations promotes PTPRJ access to its RTK substrates (e.g., EGFR and FLT3), reduces RTK's phosphorylation and downstream signaling, and ultimately antagonizes RTK-driven cell phenotypes. Here, we designed and tested a series of first-in-class pH-responsive TM peptide agonists of PTPRJ that are soluble in aqueous solution but insert as a helical TM domain in lipid membranes when the pH is lowered to match that of the acidic microenvironment of tumors. The most promising peptide reduced EGFR's phosphorylation and inhibited cancer cell EGFR-driven migration and proliferation, similar to the PTPRJ's TM point mutations. Developing tumor-selective and TM-targeting peptide binders of critical RPTPs could afford a potentially transformative approach to studying RPTP's selectivity mechanism without requiring less specific inhibitors and represent a novel class of therapeutics against RTK-driven cancers.

Pleiotrophin ameliorates age-induced adult hippocampal neurogenesis decline and cognitive dysfunction

Cognitive impairment has been associated with an age-related decline in adult hippocampal neurogenesis (AHN). The molecular basis of declining neurogenesis in the aging hippocampus remains to be elucidated. Here, we show that pleiotrophin (PTN) expression is decreased with aging in neural stem and progenitor cells (NSPCs). Mice lacking PTN exhibit impaired AHN accompanied by poor learning and memory. Mechanistically, we find that PTN engages with protein tyrosine phosphatase receptor type Z1 (PTPRZ1) to promote NSPC proliferation and differentiation by activating AKT signaling. PTN overexpression or pharmacological activation of AKT signaling in aging mice restores AHN and alleviates relevant memory deficits. Importantly, we also find that PTN overexpression improves impaired neurogenesis in senescence-accelerated mouse prone 8 (SAMP8) mice. We further confirm that PTN is required for enriched environment-induced increases in AHN. These results corroborate the significance of AHN in aging and reveal a possible therapeutic intervention by targeting PTN.

Effectiveness of exercise and pramipexole in the treatment of restless leg syndrome: Implications on the dopaminergic system and PTPRD

ObjectiveDopaminergic dysfunction, iron reduction and variations in the PTPRD gene (protein tyrosine phosphatase receptor type delta) may be associated with restless leg syndrome (RLS). Here, we evaluate the effect of pramipexole (PPX) and exercise on genes and proteins associated with RLS and on sleep patterns in spontaneously hypertensive rats (SHR). MethodsAnimals were distributed into 4 groups: 1) Control (CTRL); 2) Exercise (EX); 3) Exercise and pramipexole (EX + PPX); and 4) Pramipexole (PPX). PPX treatment was performed daily (0.125 mg/kg), while exercise was conducted over 5 sessions per week, both for 4 weeks. ResultsEX + PPX increased the protein levels of PTPRD, reduced the protein levels of the enzyme tyrosine hydroxylase (TH) and improved sleep parameters in both cycles; on the other hand, the use of PPX reduced mRNA and protein levels of PTPRD and TH but improved the sleep pattern in the light cycle. However, in the dark cycle, pramipexole caused the worsening of symptoms. ConclusionsWe suggest that the improvement in sleep pattern by EX + PPX may be associated with the increased protein levels of PTPRD and that EX + PPX can reverse the negative effects of PPX.

Brain-specific glycosylation enzyme GnT-IX maintains levels of protein tyrosine phosphatase receptor PTPRZ, thereby mediating glioma growth

Gliomas are the most prevalent primary tumor of the CNS. Despite advances in imaging technologies, neurosurgical techniques, and radiotherapy, a cure for high-grade glioma remains elusive. Several groups have reported that protein tyrosine phosphatase receptor Z (PTPRZ) is highly expressed in glioblastoma, and that targeting PTPRZ attenuates tumor growth in mice. PTPRZ is modified with diverse glycan, including the PTPRZ-unique human natural killer-1 (HNK-1) capped O-Man core M2 glycans. However, the regulation and function of these unique glycans are unclear. Using CRISPR genome-editing technology we first demonstrated that disruption of the PTPRZ gene in human glioma LN-229 cells resulted in profoundly reduced tumor growth in xenografted mice, confirming the potential of PTPRZ as a therapeutic target for glioma. Furthermore, multiple glycan analyses revealed that PTPRZ derived from glioma patients and from xenografted glioma expressed abundant levels of HNK-1 capped O-Man glycans via extrinsic signals. Finally, since deficiency of O-Man core M2 branching enzyme N-acetylglucosaminyltransferase IX (GnT-IX) was reported to reduce PTPRZ protein levels, we disrupted the GnT-IX gene in LN-229 cells and found a significant reduction of glioma growth both in vitro and in the xenograft model. These results suggest that the PTPR glycosylation enzyme GnT-IX may represent a promising therapeutic target for glioma.

Advancing therapeutics using antibody-induced dimerization of receptor tyrosine phosphatases.

Receptor protein tyrosine phosphatases (RPTPs) are involved in a broad list of cellular, developmental, and physiological functions. Altering their expression leads to significant changes in protein phosphorylation linked to a growing list of human diseases, including cancers and neurological disorders. In this issue of Genes & Development, Qian and colleagues (pp. 743-759) present the identification of a monoclonal antibody targeting PTPRD extracellular domain-inducing dimerization and inhibition of the phosphatase activities, causing the proteolysis of dimeric PTPRD by a mechanism involving intracellular degradation pathways. Their study supports the potential of modulating PTPRD via its extracellular domains. This opens a new framework in the clinical manipulation of PTPRD and its closely related family members.

Manipulating PTPRD function with ectodomain antibodies.

Protein tyrosine phosphatases (PTPs) are critical regulators of signal transduction but have yet to be exploited fully for drug development. Receptor protein tyrosine phosphatase δ (RPTPδ/PTPRD) has been shown to elicit tumor-promoting functions, including elevating SRC activity and promoting metastasis in certain cell contexts. Dimerization has been implicated in the inhibition of receptor protein tyrosine phosphatases (RPTPs). We have generated antibodies targeting PTPRD ectodomains with the goal of manipulating their dimerization status ectopically, thereby regulating intracellular signaling. We have validated antibody binding to endogenous PTPRD in a metastatic breast cancer cell line, CAL51, and demonstrated that a monoclonal antibody, RD-43, inhibited phosphatase activity and induced the degradation of PTPRD. Similar effects were observed following chemically induced dimerization of its phosphatase domain. Mechanistically, RD-43 triggered the formation of PTPRD dimers in which the phosphatase activity was impaired. Subsequently, the mAb-PTPRD dimer complex was degraded through lysosomal and proteasomal pathways, independently of secretase cleavage. Consequently, treatment with RD-43 inhibited SRC signaling and suppressed PTPRD-dependent cell invasion. Together, these findings demonstrate that manipulating RPTP function via antibodies to the extracellular segments has therapeutic potential.

Small molecule antagonists of PTPmu identified by artificial intelligence-based computational screening block glioma cell migration and growth.

PTPmu (PTPμ) is a member of the receptor protein tyrosine phosphatase IIb family that participates in both homophilic cell-cell adhesion and signaling. PTPmu is proteolytically downregulated in glioblastoma generating extracellular and intracellular fragments that have oncogenic activity. The intracellular fragments, in particular, are known to accumulate in the cytoplasm and nucleus where they interact with inappropriate binding partners/substrates generating signals required for glioma cell migration and growth. Thus, interfering with these fragments is an attractive therapeutic strategy. To develop agents that target these fragments, we used the AI-based AtomNetⓇ model, a drug design and discovery tool, to virtually screen molecular libraries for compounds able to target a binding pocket bordered by the wedge domain, a known regulatory motif located within the juxtamembrane portion of the protein. Seventy-four high-scoring and chemically diverse virtual hits were then screened in multiple cell-based assays for effects on glioma cell motility (scratch assays) and growth in 3D culture (sphere assays), and PTPmu-dependent adhesion (Sf9 aggregation). We identified three inhibitors (247678835, 247682206, 247678791) that affected the motility of multiple glioma cell lines (LN229, U87MG, and Gli36delta5), the growth of LN229 and Gli36 spheres, and PTPmu-dependent Sf9 aggregation. Compound 247678791 was further shown to suppress PTPmu enzymatic activity in an in vitro phosphatase assay, and 247678835 was able to inhibit the growth of human glioma tumors in mice. We propose that these three compounds are PTPmu-targeting agents with therapeutic potential for treating glioblastoma.

GENETIC POLYMORPHISMS OF SERINE RACEMASE AND PROTEIN TYROSINE PHOSPHATASE RECEPTOR TYPE D ASSOCIATED WITH TYPE 2 DIABETES IN MALAY SUBJECTS

Background and objectives: Serine racemase (SRR) and protein tyrosine phosphatase receptor type D (PTPRD) were suggested as Type 2 diabetes mellitus (T2DM) candidate genes by a genome-wide association study (GWAS) in the Chinese population. Association of SRR and PTPRD with T2DM have been reported among East Asian Populations. The association of SRR and PTPRD genetic polymorphisms with T2DM still needs to be studied in Southeast Asian Populations. Materials and Methods: This study aimed to evaluate the association of SRR and PTPRD genetic polymorphisms with T2DM in Malay subjects. The single nucleotide polymorphisms (SNPs) of SRR (rs4523957, rs391300, and rs8081273) and PTPRD (rs17584499 and rs649891) were genotyped in 440 T2DM and 398 normal Malay subjects. Results: The recessive genetic model showed that SRR genotype GG of rs4523957 and genotype TT of rs391300 are risk factors for T2DM (OR=1.42; 1.45, p=0.022; 0.020, respectively), whereas the dominant and additive genetic models showed that PTPRD SNPs rs17584499 were protective for T2DM (OR=0.76; 0.77, p=0.033; 0.031, respectively). Conclusion: This study replicated the association of SRR rs4523957, rs391300, and PTPRD rs17584499 genetic polymorphisms with T2DM in Malay, while more investigation in different populations is required to confirm this finding. Peer Review History: Received: 9 March 2023; Revised: 23 April; Accepted: 26 June 2023, Available online: 15 July 2023 Academic Editor: Dr. Amany Mohamed Alboghdadly, Ibn Sina National College for Medical Studies in Jeddah, Saudi Arabia, amanyalboghdadly@gmail.com Received file: Reviewer's Comments: Average Peer review marks at initial stage: 5.0/10 Average Peer review marks at publication stage: 7.0/10 Reviewers: Rola Jadallah, Arab American University, Palestine, rola@aauj.edu Dr. Dennis Amaechi, MrsFoluBabade Mini Estate , Flat 5 by Old Soldiers Quarter, Sabongari/Bwari, Abuja- Federal Capital Territory, Nigeria. amaechitoexcel@yahoo.com

Role of protein tyrosine phosphatase receptor type M in epithelial ovarian cancer progression

BackgroundEpithelial ovarian cancer (EOC) is often diagnosed at advanced stages with low survival rates. Protein tyrosine phosphatase receptor type M (PTPRM) is involved in cancer development and progression; however, its role in EOC remains unclear. In this study,we aimed to detect PTPRM expression in ovarian epithelial tumors, analyze its relationship with the clinicopathological features and survival prognosis of patients with EOC, and provide a theoretical basis for new targets for EOC treatment. Fifty-seven patients with EOC treated at our hospital between January 2012–January 2014 were included; along with 18 borderline and 30 benign epithelial ovarian tumors and 15 normal ovarian and uterine tube tissue samples from patients surgically treated at our hospital during the same period. PTPRM expression was immunohistochemically detected, and we analyzed its relationship with clinicopathological features and prognosis. Associations between PTPRM expression and survival prognosis of patients with EOC were analyzed using the Gene Expression Profiling Interactive Analysis (GEPIA) and Kaplan–Meier Plotter databases.ResultsPTPRM had the highest expression rates in normal ovarian and uterine tube tissues, followed by benign and borderline epithelial ovarian tumors; the lowest positive expression rate was observed in EOC tumors. PTPRM expression differed significantly among groups (P < 0.05). The positive PTPRM expression rate significantly decreased with age, progressing clinical stage, and tumor recurrence, and the larger the mass diameter, the higher the positive PTPRM expression rate. PTPRM expression was significantly lower in ovarian cancer compared with that in normal tissues in the GEPIA database (P < 0.05). The overall survival (OS) and disease-free survival(DFS) rates were higher in the PTPRM high-expression group, with statistically significant (P < 0.05) and insignificant (P > 0.05) differences, respectively. The OS rate of the high-expression group compared with the low-expression group in the Kaplan–Meier Plotter database was higher, although without statistical significance (P > 0.05), and progression-free survival(PFS) was higher with statistical significance (P < 0.05).ConclusionPTPRM expression was low in patients with EOC, and the PTPRM positive-expression rate significantly decreased with progressing stages of EOC and tumor recurrence, suggesting that PTPRM acts as a tumor suppressor in EOC progression. Negative PTPRM expression may predict poor clinical outcomes in patients with EOC.

Protein–protein interactions between tenascin-R and RPTPζ/phosphacan are critical to maintain the architecture of perineuronal nets

Neural plasticity, the ability to alter the structure and function of neural circuits, varies throughout the age of an individual. The end of the hyperplastic period in the central nervous system coincides with the appearance of honeycomb-like structures called perineuronal nets (PNNs) that surround a subset of neurons. PNNs are a condensed form of neural extracellular matrix that include the glycosaminoglycan hyaluronan and extracellular matrix proteins such as aggrecan and tenascin-R (TNR). PNNs are key regulators of developmental neural plasticity and cognitive functions, yet our current understanding of the molecular interactions that help assemble them remains limited. Disruption of Ptprz1, the gene encoding the receptor protein tyrosine phosphatase RPTPζ, altered the appearance of nets from a reticulated structure to puncta on the surface of cortical neuron bodies in adult mice. The structural alterations mirror those found in Tnr-/- mice, and TNR is absent from the net structures that form in dissociated cultures of Ptprz1-/- cortical neurons. These findings raised the possibility that TNR and RPTPζ cooperate to promote the assembly of PNNs. Here, we show that TNR associates with the RPTPζ ectodomain and provide a structural basis for these interactions. Furthermore, we show that RPTPζ forms an identical complex with tenascin-C, a homolog of TNR that also regulates neural plasticity. Finally, we demonstrate that mutating residues at the RPTPζ-TNR interface impairs the formation of PNNs in dissociated neuronal cultures. Overall, this work sets the stage for analyzing the roles of protein-protein interactions that underpin the formation of nets.

Genetic deletion or tyrosine phosphatase inhibition of PTPRZ1 activates c-Met to up-regulate angiogenesis and lung adenocarcinoma growth.

Protein tyrosine phosphatase receptor zeta 1 (PTPRZ1) is a transmembrane tyrosine phosphatase (TP) expressed in endothelial cells and required for stimulation of cell migration by vascular endothelial growth factor A165 (VEGFA165 ) and pleiotrophin (PTN). It is also over or under-expressed in various tumor types. In this study, we used genetically engineered Ptprz1-/- and Ptprz1+/+ mice to study mechanistic aspects of PTPRZ1 involvement in angiogenesis and investigate its role in lung adenocarcinoma (LUAD) growth. Ptprz1-/- lung microvascular endothelial cells (LMVEC) have increased angiogenic features compared with Ptprz1+/+ LMVEC, in line with the increased lung angiogenesis and the enhanced chemically induced LUAD growth in Ptprz1-/- compared with Ptprz1+/+ mice. In LUAD cells isolated from the lungs of urethane-treated mice, PTPRZ1 TP inhibition also enhanced proliferation and migration. Expression of beta 3 (β3 ) integrin is decreased in Ptprz1-/- LMVEC, linked to enhanced VEGF receptor 2 (VEGFR2), c-Met tyrosine kinase (TK) and Akt kinase activities. However, only c-Met and Akt seem responsible for the enhanced endothelial cell activation in vitro and LUAD growth and angiogenesis in vivo in Ptprz1-/- mice. A selective PTPRZ1 TP inhibitor, VEGFA165 and PTN also activate c-Met and Akt in a PTPRZ1-dependent manner in endothelial cells, and their stimulatory effects are abolished by the c-Met TK inhibitor (TKI) crizotinib. Altogether, our data suggest that low PTPRZ1 expression is linked to worse LUAD prognosis and response to c-Met TKIs and uncover for the first time the role of PTPRZ1 in mediating c-Met activation by VEGFA and PTN.

Mice lacking Ptprd exhibit deficits in goal-directed behavior and female-specific impairments in sensorimotor gating.

Protein Tyrosine Phosphatase receptor type D (PTPRD) is a member of the protein tyrosine phosphatase family that mediates cell adhesion and synaptic specification. Genetic studies have linked Ptprd to several neuropsychiatric phenotypes, including Restless Leg Syndrome (RLS), opioid abuse disorder, and antipsychotic-induced weight gain. Genome-wide association studies (GWAS) of either pediatric obsessive-compulsive traits, or Obsessive-Compulsive Disorder (OCD), have identified loci near PTPRD as genome-wide significant, or strongly suggestive for this trait. We assessed Ptprd wild-type (WT), heterozygous (HT), and knockout (KO) mice for behavioral dimensions that are altered in OCD, including anxiety and exploration (open field test, dig test), perseverative behavior (splash-induced grooming, spatial d), sensorimotor gating (prepulse inhibition), and home cage goal-directed behavior (nest building). No effect of genotype was observed in any measure of the open field test, dig test, or splash test. However, Ptprd KO mice of both sexes showed impairments in nest building behavior. Finally, female, but not male, Ptprd KO mice showed deficits in prepulse inhibition, an operational measure of sensorimotor gating that is reduced in female, but not male, OCD patients. Our results indicate that constitutive lack of Ptprd may contribute to the development of certain domains that are altered OCD, including goal-directed behavior, and reduced sensorimotor gating specifically in females.

Axonal growth inhibitors and their receptors in spinal cord injury: from biology to clinical translation.

Axonal growth inhibitors are released during traumatic injuries to the adult mammalian central nervous system, including after spinal cord injury. These molecules accumulate at the injury site and form a highly inhibitory environment for axonal regeneration. Among these inhibitory molecules, myelin-associated inhibitors, including neurite outgrowth inhibitor A, oligodendrocyte myelin glycoprotein, myelin-associated glycoprotein, chondroitin sulfate proteoglycans and repulsive guidance molecule A are of particular importance. Due to their inhibitory nature, they represent exciting molecular targets to study axonal inhibition and regeneration after central injuries. These molecules are mainly produced by neurons, oligodendrocytes, and astrocytes within the scar and in its immediate vicinity. They exert their effects by binding to specific receptors, localized in the membranes of neurons. Receptors for these inhibitory cues include Nogo receptor 1, leucine-rich repeat, and Ig domain containing 1 and p75 neurotrophin receptor/tumor necrosis factor receptor superfamily member 19 (that form a receptor complex that binds all myelin-associated inhibitors), and also paired immunoglobulin-like receptor B. Chondroitin sulfate proteoglycans and repulsive guidance molecule A bind to Nogo receptor 1, Nogo receptor 3, receptor protein tyrosine phosphatase σ and leucocyte common antigen related phosphatase, and neogenin, respectively. Once activated, these receptors initiate downstream signaling pathways, the most common amongst them being the RhoA/ROCK signaling pathway. These signaling cascades result in actin depolymerization, neurite outgrowth inhibition, and failure to regenerate after spinal cord injury. Currently, there are no approved pharmacological treatments to overcome spinal cord injuries other than physical rehabilitation and management of the array of symptoms brought on by spinal cord injuries. However, several novel therapies aiming to modulate these inhibitory proteins and/or their receptors are under investigation in ongoing clinical trials. Investigation has also been demonstrating that combinatorial therapies of growth inhibitors with other therapies, such as growth factors or stem-cell therapies, produce stronger results and their potential application in the clinics opens new venues in spinal cord injury treatment.

Protein tyrosine phosphatase receptors N and N2 regulate gonadotropin-releasing hormone neuron function

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)