Phosphodiesterase 10A Protein Research Articles

Chorea-related mutations in PDE10A result in aberrant compartmentalization and functionality of the enzyme

A robust body of evidence supports the concept that phosphodiesterase 10A (PDE10A) activity in the basal ganglia orchestrates the control of coordinated movement in human subjects. Although human mutations in the PDE10A gene manifest in hyperkinetic movement disorders that phenocopy many features of early Huntington's disease, characterization of the maladapted molecular mechanisms and aberrant signaling processes that underpin these conditions remains scarce. Recessive mutations in the GAF-A domain have been shown to impair PDE10A function due to the loss of striatal PDE10A protein levels, but here we show that this paucity is caused by irregular intracellular trafficking and increased PDE10A degradation in the cytosolic compartment. In contrast to GAF-A mutants, dominant mutations in the GAF-B domain of PDE10A induce PDE10A misfolding, a common pathological phenotype in many neurodegenerative diseases. These data demonstrate that the function of striatal PDE10A is compromised in disorders where disease-associated mutations trigger a reduction in the fidelity of PDE compartmentalization.

Sex differences in the long-term effects of past stress on alcohol self-administration, glucocorticoid sensitivity and phosphodiesterase 10A expression

Stress responses differ by sex, and females are more susceptible to developing mental illnesses because of past stress, including alcohol use disorder. Investigation of neuroadaptations governing the interaction between past stress and future alcohol intake remains understudied in females. A history of footshock stress previously was shown to increase alcohol self-administration under relapse-like conditions in male rats, associated with elevated phosphodiesterase 10A (PDE10A) mRNA expression in the dorsomedial prefrontal cortex and basolateral amygdala. To identify sex differences in long-term stress effects, male and female Wistar rats were exposed to light-cued footshock stress prior to alcohol self-administration training. While past stress did not alter acquisition or extinction, reacquisition self-administration was oppositely impacted by past stress. Stress history slightly increased reacquisition self-administration in males, but reduced alcohol self-administration in females, relative to same-sex controls. Control females self-administered less alcohol following glucocorticoid receptor inhibition by mifepristone, which did not significantly alter alcohol consumption in the other groups. PDE10A expression in synaptically enriched fractions also differed by sex and stress history in a brain region-specific manner. Females expressed more synaptic PDE10A than males in basolateral amygdala and dorsolateral striatum, regardless of stress history, whereas dorsomedial prefrontal cortex PDE10A protein levels matched group differences in reacquisition drinking, but also were expressed at much lower levels than all other regions examined. Together, these data show stress history differentially impacts alcohol self-administration and PDE10A expression by sex, with control females consuming alcohol in a glucocorticoid receptor-sensitive fashion that may relate to sex differences in PDE10A expression.

Fragment-Based Discovery of Pyrimido[1,2-b]indazole PDE10A Inhibitors.

In this study, we report the identification of potent pyrimidoindazoles as phosphodiesterase10A (PDE10A) inhibitors by using the method of fragment-based drug discovery (FBDD). The pyrazolopyridine derivative 2 was found to be a fragment hit compound which could occupy a part of the binding site of PDE10A enzyme by using the method of the X-ray co-crystal structure analysis. On the basis of the crystal structure of compound 2 and PDE10A protein, a number of compounds were synthesized and evaluated, by means of structure-activity relationship (SAR) studies, which culminated in the discovery of a novel pyrimidoindazole derivative 13 having good physicochemical properties.

Abstract 5174: Phosphodiesterase 10A inhibition as a novel approach to suppress β-catenin signaling in ovarian cancer cells

Abstract Canonical Wnt/β-catenin signaling is known to be associated with platinum resistance in ovarian cancer in which inhibitors hold promise for the treatment of refractory disease. Phosphodiesterase 10A (PDE10A) is a dual cyclic AMP and cyclic GMP phosphodiesterase isozyme recently implicated in colon cancer. PDE10A inhibition in colon cancer cells by siRNA or small molecule inhibitors increased cGMP levels and activated PKG to inhibit β-catenin signaling. A novel PDE10 inhibitor, ADT-061, was identified by screening a library of indene derivatives, and showed strong antineoplastic activity in the Apc+/min-FCCC mouse (Lee K et al., unpublished data). Cyclic GMP and phosphodiesterases participate in the ovarian follicular development, although little is known about PDE10A expression in ovaries, especially with regard to a potential role in ovarian tumorigenesis. PDE10A protein was found to be expressed in various established ovarian cancer cell lines at higher levels than immortalized or primary ovarian surface epithelial cell lines. Pf-2545920, a known PDE10A inhibitor, and ADT-061 inhibited the growth of multiple ovarian tumor cell lines with IC50s around 20µM and 0.5µM, respectively. Both compounds induced apoptosis after 24h treatment, as measured by PI/Annexin-V staining and PARP cleavage. Pf-2545920 and ADT-061 induced phosphorylation of VASP at Ser157 and Ser239 in various ovarian cancer cell lines, indicating activation of cyclic AMP and cyclic GMP signaling, respectively. Treatment also decreased levels of β-catenin and downstream targets of TCF-dependent transcription, including c-MYC, survivin and cyclin-D1. Homozygous knockout PDE10A clones of OV-90 ovarian cancer cells obtained using CRISPR/Cas9 showed decreased clonogenic potential, decreased Pf-2545920-mediated VASP phosphorylation and β-catenin, c-MYC and survivin expression. Ongoing efforts are focused on the development of more potent ADT-061 analogs. These observations support further study of a role of PDE10 in ovarian tumorigenesis and the development of ADT-061 or analogs for the treatment of refractory ovarian cancer as well as the prevention of malignant recurrence. Citation Format: Luciana Madeira Da Silva, Elaine Gavin, Kevin J. Lee, Veronica Ramírez-Alcántara, Kristy L. Berry, Holly T. Taylor, Alla Musiyenko, Ileana V. Aragon, Adam B. Keeton, Jennifer Scalici, Rodney P. Rocconi, Gary A. Piazza. Phosphodiesterase 10A inhibition as a novel approach to suppress β-catenin signaling in ovarian cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5174. doi:10.1158/1538-7445.AM2017-5174

PET imaging shows loss of striatal PDE10A in patients with Huntington disease

Phosphodiesterase 10A (PDE10A) belongs to a family of enzymes that hydrolyze cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate.(1) PDE10A is highly enriched in striatal medium spiny neurons (MSNs), where it regulates intracellular signaling.(1) PDE10A has been proposed as a therapeutic target for Huntington disease (HD), a disorder that preferentially affects MSNs, based on the observation that pharmacologic inhibition of PDE10A in transgenic HD mice significantly improved behavioral and neuropathologic abnormalities.(2) However, earlier work had shown that striatal PDE10A levels in HD mice already decline to minimal levels before onset of motor symptoms,(3) possibly because mutant huntingtin represses PDE10A transcription. Also, postmortem analysis of striatum of 3 patients with HD revealed strong reduction of PDE10A levels.(3) Depletion of PDE10A in HD striatum would at first sight seem hard to reconcile with a beneficial effect of PDE10A inhibitors in HD. However, a recent study reported a dramatic increase, rather than decrease, of PDE10A protein in MSNs of HD mice.(4) In light of these conflicting results and the strong interest in development of PDE10A inhibitors for clinical use in HD, it is important to determine whether PDE10A levels are affected in the striatum of patients with HD in vivo.

PDE10A and PDE10A-dependent cAMP catabolism are dysregulated oppositely in striatum and nucleus accumbens after lesion of midbrain dopamine neurons in rat: A key step in parkinsonism physiopathology

Loss of dopamine neurons in experimental parkinsonism results in altered cyclic nucleotide cAMP and cGMP levels throughout the basal ganglia. Our objective was to examine whether expression of phosphodiesterase 10A (PDE10A), an isozyme presenting a unique distribution in basal ganglia, is altered after unilateral injection of 6-hydroxydopamine in the medial forebrain bundle, eliminating all midbrain dopaminergic neurons, such that cyclic nucleotide catabolism and steady state could be affected. Our study demonstrates that PDE10A mRNA levels were decreased in striatal neurons 10weeks after 6-hydroxydopamine midbrain lesion. Such changes occurred in the striatum ipsilateral to lesion and were paralleled by decreased PDE10A protein levels and activity in striatal neurons and in striato-pallidal and striato-nigral projections. However, PDE10A protein and activity were increased while PDE10A mRNA was unchanged in the nucleus accumbens ipsilateral to the 6-hydroxydopamine midbrain lesion. Accordingly, cAMP levels were down-regulated in the nucleus accumbens, and up-regulated in the striatum ipsilateral to the lesion, but they were not significantly changed in substantia nigra and globus pallidus. Unlike cAMP, cGMP levels were decreased in all dopamine-deafferented regions. The opposite variations of cAMP steady state in striatum and nucleus accumbens are concordant and likely dependent, at least in part, on the down-regulation of PDE10A expression and activity in the former and its up-regulation in the latter. On the other hand, the down-regulation of cGMP steady state in the striato-nigral and striato-pallidal complex is not consistent with and is likely independent from the concomitant down-regulation of PDE10A. Therefore, dopamine loss inversely regulates PDE10A gene expression in the striatum and PDE10A post-transcription in the nucleus accumbens, therein differentially modulating PDE10A-dependent cAMP catabolism.

Phosphodiesterase 10A in the Rat Pineal Gland: Localization, Daily and Seasonal Regulation of Expression and Influence on Signal Transduction

The cyclic nucleotide phosphodiesterase 10A (PDE10A) is highly expressed in striatal spiny projection neurons and represents a therapeutic target for the treatment of psychotic symptoms. As reported previously [J Biol Chem 2009; 284:7606–7622], in this study PDE10A was seen to be additionally expressed in the pineal gland where the levels of PDE10A transcript display daily changes. As with the transcript, the amount of PDE10A protein was found to be under daily and seasonal regulation. The observed cyclicity in the amount of PDE10A mRNA persists under constant darkness, is blocked by constant light and is modulated by the lighting regime. It therefore appears to be driven by the master clock in the suprachiasmatic nucleus (SCN). Since adrenergic agonists and dibutyryl-cAMP induce PDE10A mRNA, the in vitro clock-dependent control of Pde10a appears to be mediated via a norepinephrine → β-adrenoceptor → cAMP/protein kinase A signaling pathway. With regard to the physiological role of PDE10A in the pineal gland, the specific PDE10A inhibitor papaverine was seen to enhance the adrenergic stimulation of the second messenger cAMP and cGMP. This indicates that PDE10A downregulates adrenergic cAMP and cGMP signaling by decreasing the half-life of both nucleotides. Consistent with its effect on cAMP, PDE10A inhibition also amplifies adrenergic induction of the cAMP-inducible gene arylalkylamine N-acetyltransferase (Aanat) which codes the rate-limiting enzyme in pineal melatonin formation. The findings of this study suggest that Pde10a expression is under circadian and seasonal regulation and plays a modulatory role in pineal signal transduction and gene expression.

Phosphodiesterase10A: Abundance and circadian regulation in the retina and photoreceptor of the rat

Phosphodiesterase10A (PDE10A) is a dual specific cyclic nucleotide phosphodiesterase that is specifically enriched in striatum and which has gained attention as a therapeutic target for psychiatric disorders. The present study shows that PDE10A is also highly expressed in retinal neurons including photoreceptors. The levels of PDE10A transcript and protein display daily rhythms which could be seen in preparations of the whole retina. Corresponding changes in PDE10A mRNA were seen in photoreceptors isolated using laser microdissection. This suggests that the expressional control of the photoreceptor Pde10a gene contributes to the observed cyclicity in the amount of retinal PDE10A. The daily rhythmicity in the retinal PDE10A mRNA amount is retained under constant darkness but can be blocked by constant light or modulated by the lighting regime. It therefore appears to be driven by the endogenous retinal clock system which itself is entrained by light. The findings presented place PDE10A in the context of the visual system and suggest a role of PDE10A in the adaptation of cyclic nucleotide signaling to daily changes in light intensity in retinal neurons including photoreceptors.

Phosphodiesterase 10A inhibition is associated with locomotor and cognitive deficits and increased anxiety in mice

Phosphodiesterase 10A (PDE10A) mRNA and protein levels decline in the striatum of R6/1 and R6/2 Huntington’s disease (HD) mice prior to motor symptom development. In human HD, PDE10A protein levels are significantly decreased in the caudate-putamen of patients with grade 3 HD compared to age-matched controls. To test whether the loss of PDE10A activity in the striatum was detrimental to normal brain function, we treated wild-type (WT) mice with chronic administration of papaverine, which is a specific inhibitor of PDE10A. At 7 weeks of age, mice were introduced to a weekly battery of motor tests, including assessment of weight, locomotion, gait, and coordination. Beginning at 8 weeks of age, mice received 0, 5, 10 or 20 mg/kg papaverine once daily until the completion of behavioral testing. Following 14 days of papaverine injections, mice were assessed for deficits in cognitive performance as measured in the Morris water maze (MWM). All behavioral tests occurred either immediately prior to or 30 min following a subcutaneous papaverine challenge dose. Twenty-four hours following completion of the 2–3 week MWM protocol, mice were given a dose of papaverine and 30 min later psychological function assessed in the Light–Dark (LD) Test. Chronic administration of papaverine for 42 days was associated with distinct motor perturbations, mild cognitive disturbance and anxiety-like behaviors. Subsequently, we assessed the effect of 14 days papaverine (i.e. sub-chronic) treatment on psychological function of WT and R6/1 HD mice. While sub-chronic papaverine induced anxiety-like behavior in WT mice, it appeared to have little effect on the behavior of R6/1 HD mice. Finally, a separate group of 6-week old WT and R6/2 HD mice were treated for 21 days with saline or 10 mg/kg fluoxetine, an agent with anxiolytic and anti-depressant effects, in order to compare the effects of papaverine and fluoxetine on anxiety-like behavior in the LD test. CREB and PDE10A protein levels in striatum and hippocampus were determined by western blot. While papaverine treatment reduced CREB protein levels in the hippocampus and striatum, fluoxetine increased CREB in the hippocampus. These data suggest that papaverine and fluoxetine may produce quite different effects on behavior; these behaviors may be linked to CREB expression in brain regions associated with motor and cognitive functions. PDE10A protein levels were decreased by both papaverine and fluoxetine. Chronic PDE10A inhibition produced a variety of behavioral and central neurochemical deficits and these effects were exacerbated by stress. The unique localization of PDE10A and its apparent role in basal ganglia function may underlie its role in psychiatric and neurological disorders involving the basal ganglia.

Phosphodiesterase 10A inhibitors as a novel therapeutic approach for schizophrenia

Phosphodiesterase 10A (PDE10A) is a recently identified member of the cyclic nucleotide phosphodiesterase family. PDE10A is notable in that it has a relatively restricted distribution: PDE10A mRNA and protein are expressed primarily in the dopaminoreceptive medium spiny neurons of the striatum. Potent and selective PDE10A inhibitors have recently been described in the scientific literature and their in vivo effects suggest the potential uses of PDE10A inhibitors in CNS disorders, particularly schizophrenia. This article provides a brief overview of the presently available scientific literature as well as recent meeting presentations.

Striatal phosphodiesterase mRNA and protein levels are reduced in Huntington′s disease transgenic mice prior to the onset of motor symptoms

Inheritance of a single copy of the gene encoding huntingtin ( HD) with an expanded polyglutamine-encoding CAG repeat leads to neuronal dysfunction, neurodegeneration and the development of the symptoms of Huntington's disease (HD). We have found that the steady-state mRNA levels of two members of the phosphodiesterase (PDE) multi-gene family decrease over time in the striatum of R6 transgenic HD mice relative to age-matched wild-type littermates. Phosphodiesterase 10A (PDE10A) mRNA and protein levels decline in the striatum of R6/1 and R6/2 HD mice prior to motor symptom development. The rate of reduction in PDE10A protein correlates with the rate of decline of the message and the decrease in PDE10A mRNA and protein is more rapid in R6/2 compared with R6/1 mice. Both PDE10A protein and mRNA, therefore, decline to minimum levels prior to the onset of overt physical symptoms in both strains of transgenic mice. Moreover, protein levels of PDE10A are decreased in the caudate-putamen of grade 3 HD patients compared with age-matched neuropathologically normal controls. Striatal PDE1B mRNA levels also decline in R6/1 and R6/2 HD mice; however, the decrease in striatal PDE10A levels (>60%) was greater than that observed for PDE1B and immediately preceded the onset of motor symptoms. In contrast, PDE4A mRNA levels are relatively low in the striatum and do not differ between age-matched wild-type and transgenic HD mice. This suggests that the regulation of PDE10A and PDE1B, but not PDE4A, mRNA levels is dependent on the relative expression of or number of CAG repeats within the human HD transgene. The loss of phosphodiesterase activity may lead to dysregulation of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) levels in the striatum, a region of the brain that contributes to the control of movement and cognition.