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Age-related abnormalities in phosphodiesterase 11A (PDE11A), which degrades 3',5'-cAMP/cGMP and is enriched in the ventral hippocampus (VHIPP), drive age-related cognitive decline (ARCD) of social memories. Age-related PDE11A4 ectopically accumulates within the membrane compartment and in filamentous structures termed ghost axons. Previous studies show that expressing an isolated PDE11A4-GAF-B binding domain disrupts homodimerization and reverses aging-like PDE11A4 accumulations in vitro. Here, we show that in vivo lentiviral expression of the isolated PDE11A4-GAFB domain in hippocampal CA1 of aged mice reverses age-related PDE11A4 accumulations and ARCD of social transmission of food preference memory (STFP). It also improves 7-day remote long-term memory for social odor recognition without affecting non-social odor recognition. In vitro studies show that disrupting homodimerization does not alter the catalytic activity of PDE11A4 but may reverse age-related decreases in cGMP by relocating PDE11A4 from a cGMP-rich to a cAMP-rich pool independently of other intramolecular relocation signals (PDE11A4-pS162). Altogether, these data suggest that a biologic designed to disrupt PDE11A4 homodimerization may hold therapeutic potential for age-related PDE11A4 proteinopathies., Competing Interests: Disclosure statement The authors report no competing interests., (Copyright © 2023 Elsevier Inc. All rights reserved.)

In humans, associative memories are more susceptible to age-related cognitive decline (ARCD) than are recognition memories. Reduced cAMP/cGMP signaling in the hippocampus may contribute to ARCD. Here, we found that both aging and traumatic brain injury-associated dementia increased the expression of the cAMP/cGMP-degrading enzyme phosphodiesterase 11A (PDE11A) in the human hippocampus. Further, age-related increases in hippocampal PDE11A4 mRNA and protein were conserved in mice, as was the increased vulnerability of associative versus recognition memories to ARCD. Interestingly, mouse PDE11A4 protein in the aged ventral hippocampus (VHIPP) ectopically accumulated in the membrane fraction and filamentous structures we term "ghost axons." These age-related increases in expression were driven by reduced exoribonuclease-mediated degradation of PDE11A mRNA and increased PDE11A4-pS117/pS124, the latter of which also drove the punctate accumulation of PDE11A4. In contrast, PDE11A4-pS162 caused dispersal. Importantly, preventing age-related increases in PDE11 expression via genetic deletion protected mice from ARCD of short-term and remote long-term associative memory (aLTM) in the social transmission of food preference assay, albeit at the expense of recent aLTM. Further, mimicking age-related overexpression of PDE11A4 in CA1 of old KO mice caused aging-like impairments in CREB function and remote social-but not non-social-LTMs. RNA sequencing and phosphoproteomic analyses of VHIPP identified cGMP-PKG-as opposed to cAMP-PKA-as well as circadian entrainment, glutamatergic/cholinergic synapses, calcium signaling, oxytocin, and retrograde endocannabinoid signaling as mechanisms by which PDE11A deletion protects against ARCD. Together, these data suggest that PDE11A4 proteinopathies acutely impair signaling in the aged brain and contribute to ARCD of social memories., (© 2022 The Authors. Aging Cell published by Anatomical Society and John Wiley & Sons Ltd.)

Although the physical and mental benefits of friendships are clear, the neurobiological mechanisms driving mutual social preferences are not well understood. Studies in humans suggest friends are more genetically similar, particularly for targets within the 3',5'-cyclic adenosine monophosphate (cAMP) cascade. Unfortunately, human studies can not provide conclusive evidence for such a biological driver of friendship given that other genetically related factors tend to co-segregate with friendship (e.g., geographical proximity). As such, here we use mice under controlled conditions to test the hypothesis that homophily in the cAMP-degrading enzyme phosphodiesterase 11A4 (PDE11A4) can dictate mutual social preference. Using C57BL/6J and BALB/cJ mice in two different behavioral assays, we showed that mice with two intact alleles of Pde11a prefer to interact with Pde11 wild-type (WT) mice of the same genetic background over knockout (KO) mice or novel objects; whereas, Pde11 KO mice prefer to interact with Pde11 KO mice over WT mice or novel objects. This mutual social preference was seen in both adult and adolescent mice, and social preference could be eliminated or artificially elicited by strengthening or weakening PDE11A homodimerization, respectively. Stereotactic delivery of an isolated PDE11A GAF-B domain to the mouse hippocampus revealed the membrane-associated pool of PDE11A-cAMP-CREB signaling specifically within the CA1 subfield of hippocampus is most critical for regulating social preference. Our study here not only identifies PDE11A homophily as a key driver of mutual social preference across the lifespan, it offers a paradigm in which other mechanisms can be identified in a controlled fashion., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited.)

Phosphodiesterase 11A (PDE11A), an enzyme that degrades cyclic nucleotides (cAMP and cGMP), is the only PDE whose mRNA expression in brain is restricted to the hippocampal formation. Previously, we showed that chronic social isolation changes subsequent social behaviors in adult mice by reducing expression of PDE11A4 in the membrane fraction of the ventral hippocampus (VHIPP). Here we seek extend these findings by determining 1) if isolation-induced decreases in PDE11A4 require chronic social isolation or if they occur acutely and are sustained long-term, 2) if isolation-induced decreases occur uniquely in adults (i.e., not adolescents), and 3) how the loss of PDE11 signaling may increase neuroinflammation. Both acute and chronic social isolation decrease PDE11A4 expression in adult but not adolescent mice. This decrease in PDE11A4 is specific to the membrane compartment of the VHIPP, as it occurs neither in the soluble nor nuclear fractions of the VHIPP nor in any compartment of the dorsal HIPP. The effect of social isolation on membrane PDE11A4 is also selective in that PDE2A and PDE10A expression remain unchanged. Isolation-induced decreases in PDE11A4 expression appear to be functional as social isolation elicited changes in PDE11A-relevant signal transduction cascades (i.e., decreased pCamKIIα and pS6-235/236) and behavior (i.e., increased remote long-term memory for social odor recognition). Interestingly, we found that isolation-induced decreases in membrane PDE11A4 correlated with increased expression of interleukin-6 (IL-6) in the soluble fraction, suggesting pro-inflammatory signaling for this cytokine. This effect on IL-6 is consistent with the fact that PDE11A deletion increased microglia activation, although it left astrocytes unchanged. Together, these data suggest that isolation-induced decreases in PDE11A4 may alter subsequent social behavior via increased neuroinflammatory processes in adult mice., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Pilarzyk, Farmer, Porcher and Kelly.)

Systems consolidation is a process by which memories initially require the hippocampus for recent long-term memory (LTM) but then become increasingly independent of the hippocampus and more dependent on the cortex for remote LTM. Here, we study the role of phosphodiesterase 11A4 (PDE11A4) in systems consolidation. PDE11A4, which degrades cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), is preferentially expressed in neurons of CA1, the subiculum, and the adjacently connected amygdalohippocampal region. In male and female mice, deletion of PDE11A enhances remote LTM for social odor recognition and social transmission of food preference (STFP) despite eliminating or silencing recent LTM for those same social events. Measurement of a surrogate marker of neuronal activation (i.e., Arc mRNA) suggests the recent LTM deficits observed in Pde11 knockout mice correspond with decreased activation of ventral CA1 relative to wild-type littermates. In contrast, the enhanced remote LTM observed in Pde11a knockout mice corresponds with increased activation and altered functional connectivity of anterior cingulate cortex, frontal association cortex, parasubiculum, and the superficial layer of medial entorhinal cortex. The apparent increased neural activation observed in prefrontal cortex of Pde11a knockout mice during remote LTM retrieval may be related to an upregulation of the N-methyl-D-aspartate receptor subunits NR1 and NR2A. Viral restoration of PDE11A4 to vCA1 alone is sufficient to rescue both the LTM phenotypes and upregulation of NR1 exhibited by Pde11a knockout mice. Together, our findings suggest remote LTM can be decoupled from recent LTM, which may have relevance for cognitive deficits associated with aging, temporal lobe epilepsy, or transient global amnesia., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

3',5'-Cyclic nucleotide phosphodiesterases (PDEs) degrade 3',5' cyclic adenonosine monophosphate (cAMP) and 3',5' cyclic guanosine monophosphate (cGMP), with PDE9A having the highest affinity for cGMP. We show PDE9A6 and 3 novel PDE9 isoforms (PDE9X-100, PDE9X-120, and PDE9X-175) are reliably detected in the brain and lung of mice, whereas PDE9A2 and other isoforms are found elsewhere. PDE9A localizes to the membrane in all organs except the bladder, where it is cytosolic. Brain additionally shows PDE9 in the nuclear fraction. PDE9A mRNA expression/localization dramatically changes across neurodevelopment in a manner that is strikingly consistent between mice and humans (i.e., decreased expression in the hippocampus and cortex and inverted-U in the cerebellum). Study of the 4 PDE9 isoforms in the mouse brain from postnatal day 7 through 24 months similarly identifies dramatic effects of age on expression and subcellular compartmentalization that are isoform specific and brain region specific. Finally, PDE9A mRNA is elevated in the aged human hippocampus with dementia when there is a history of traumatic brain injury. Thus, brain PDE9 is localized to preferentially regulate nuclear- and membrane-proximal pools of cGMP, and its function likely changes across the life span., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background  Sparse data are available on the prevalence of right ventricular dysfunction and/or pulmonary arterial hypertension in patients scheduled for cardiac surgery in Germany as well as on the intensity and modalities used for diagnosis, perioperative monitoring, and treatment of these comorbidities. Methods  A postal survey including questions on the prevalence of preoperative right ventricular dysfunction and/or pulmonary arterial hypertension in patients undergoing cardiac surgery in 2009 was sent to 81 German heart centers. Total 47 of 81 (58%) heart centers returned the questionnaires. The centers reported data on 51,095 patients, and 49.8% of the procedures were isolated coronary artery bypass grafting. Results  Data on the prevalence of preoperative pulmonary hypertension and/or right ventricular dysfunction were not available in 54% and 64.6% of centers. In the remaining hospitals, 19.5% of patients presented right heart dysfunction and 10% pulmonary arterial hypertension. Preoperative echocardiography was performed in only 45.3% of the coronary artery bypass grafting cases. Preoperative pharmacologic treatment of pulmonary hypertension or right ventricular dysfunction with oral sildenafil, inhaled prostanoids, or nitric oxide was initiated in 71% and 95.7% of the centers, respectively. Intra- and postoperative treatment was most frequently accomplished with phosphodiesterase-III inhibitors. Conclusion  The prevalence of preoperative right heart dysfunction and pulmonary arterial hypertension in cardiac surgical patients in Germany seems to be substantial. However, in more than 50% of the patients, no preoperative data on right ventricular function and pulmonary arterial pressure are available. This may lead to underestimation of perioperative risk and inappropriate management of this high-risk population., Competing Interests: Conflict of interest: None declared., (Georg Thieme Verlag KG Stuttgart · New York.)