Soluble adenylyl cyclase contributes to imiquimod-mediated inflammation and is a potential therapeutic target in psoriasis.

Cyclic AMP (cAMP) has a key role in psoriasis pathogenesis, as indicated by the therapeutic efficacy of phosphodiesterase inhibitors that prevent the degradation of cAMP. However, whether soluble adenylate cyclase (sAC) (encoded by the ADCY10 gene), which is an important source for cAMP, is involved in Th17 cell-mediated inflammation or could be an alternative therapeutic target in psoriasis is unknown. We have utilized the imiquimod model of murine psoriasiform dermatitis to address this question. Adcy10-/- mice had reduced erythema, scaling and swelling in the skin and reduced CD4+ IL17+ cell numbers in the draining lymph nodes, compared with wild-type mice after induction of psoriasiform dermatitis with imiquimod. Keratinocyte-specific knock out of Adcy10 had no effect on imiquimod-induced ear swelling suggesting keratinocyte sAC has no role in imiquimod-induced inflammation. During Th17 polarization in vitro, naive T cells from Adcy10-/- mice exhibited reduced IL17 secretion and IL-17+ T-cell proliferation suggesting that differentiation into Th17 cells is suppressed without sAC activity. Interestingly, loss of sAC did not impact the expression of Th17 lineage-defining transcription factors (such as Rorc and cMaf) but rather was required for CREB-dependent gene expression, which is known to support Th17 cell gene expression. Finally, topical application of small molecule sAC inhibitors (sACi) reduced imiquimod-induced psoriasiform dermatitis and Il17 gene expression in the skin. Collectively, these findings demonstrate that sAC is important for psoriasiform dermatitis in mouse skin. sACi may provide an alternative class of topical therapeutics for Th17-mediated skin diseases.

A nuclear cAMP microdomain suppresses tumor growth by Hippo pathway inactivation.

Cyclic AMP (cAMP) signaling is localized to multiple spatially distinct microdomains, but the role of cAMP microdomains in cancer cell biology is poorly understood. Here, we present a tunable genetic system that allows us to activate cAMP signaling in specific microdomains. We uncover a nuclear cAMP microdomain that activates a tumor-suppressive pathway in a broad range of cancers by inhibiting YAP, a key effector protein of the Hippo pathway, inside the nucleus. We show that nuclear cAMP induces a LATS-dependent pathway leading to phosphorylation of nuclear YAP solely at serine 397 and export of YAP from the nucleus with no change in YAP protein stability. Thus, nuclear cAMP inhibition of nuclear YAP is distinct from other known mechanisms of Hippo regulation. Pharmacologic targeting of specific cAMP microdomains remains an untapped therapeutic approach for cancer; thus, drugs directed at the nuclear cAMP microdomain may provide avenues for the treatment of cancer.

Cyclic adenosine monophosphate (cAMP) signaling in melanocyte pigmentation and melanomagenesis.

The second messenger cyclic adenosine monophosphate (cAMP) regulates numerous functions in both benign melanocytes and melanoma cells. cAMP is generated from two distinct sources, transmembrane and soluble adenylyl cyclases (tmAC and sAC, respectively), and is degraded by a family of proteins called phosphodiesterases (PDEs). cAMP signaling can be regulated in many different ways and can lead to varied effects in melanocytes. It was recently revealed that distinct cAMP signaling pathways regulate pigmentation by either altering pigment gene expression or the pH of melanosomes. In the context of melanoma, many studies report seemingly contradictory roles for cAMP in tumorigenesis. For example, cAMP signaling has been implicated in both cancer promotion and suppression, as well as both therapy resistance and sensitization. This conundrum in the field may be explained by the fact that cAMP signals in discrete microdomains and each microdomain can mediate differential cellular functions. Here, we review the role of cAMP signaling microdomains in benign melanocyte biology, focusing on pigmentation, and in melanomagenesis.

Single-cell profiling reveals an endothelium-mediated immunomodulatory pathway in the eye choroid.

The activity and survival of retinal photoreceptors depend on support functions performed by the retinal pigment epithelium (RPE) and on oxygen and nutrients delivered by blood vessels in the underlying choroid. By combining single-cell and bulk RNA sequencing, we categorized mouse RPE/choroid cell types and characterized the tissue-specific transcriptomic features of choroidal endothelial cells. We found that choroidal endothelium adjacent to the RPE expresses high levels of Indian Hedgehog and identified its downstream target as stromal GLI1+ mesenchymal stem cell-like cells. In vivo genetic impairment of Hedgehog signaling induced significant loss of choroidal mast cells, as well as an altered inflammatory response and exacerbated visual function defects after retinal damage. Our studies reveal the cellular and molecular landscape of adult RPE/choroid and uncover a Hedgehog-regulated choroidal immunomodulatory signaling circuit. These results open new avenues for the study and treatment of retinal vascular diseases and choroid-related inflammatory blinding disorders.

Pyramidal cell-selective GluN1 knockout causes impairments in salience attribution and related EEG activity.

Schizophrenia is a disabling psychiatric disease characterized by symptoms including hallucinations, delusions, social withdrawal, loss of pleasure, and inappropriate affect. Although schizophrenia is marked by dysfunction in dopaminergic and glutamatergic signaling, it is not presently clear how these dysfunctions give rise to symptoms. The aberrant salience hypothesis of schizophrenia argues that abnormal attribution of motivational salience to stimuli is one of the main contributors to both positive and negative symptoms of schizophrenia. The proposed mechanisms for this hypothesis are overactive striatal dopaminergic and hypoactive glutamatergic signaling. The current study assessed salience attribution in mice (n = 72) using an oddball paradigm in which an infrequent stimulus either co-occurred with shock (conditioned group) or was presented alone (non-conditioned group). Behavioral response (freezing) and electroencephalogram (whole brain and amygdala) were used to assess salience attribution. Mice with pyramidal cell-selective knockout of ionotropic glutamate receptors (GluN1) were used to reproduce a prominent physiological change involved in schizophrenia. Non-conditioned knockout mice froze significantly more in response to the unpaired stimulus than non-conditioned wild-type mice, suggesting that this irrelevant cue acquired motivational salience for the knockouts. In accordance with this finding, low-frequency event-related spectral perturbation was significantly increased in non-conditioned knockout mice relative to both conditioned knockout and non-conditioned wild-type mice. These results suggest that pyramidal cell-selective GluN1 knockout leads to inappropriate attribution of salience for irrelevant stimuli as characterized by abnormalities in both behavior and brain circuitry functions.

EEG biomarkers of target engagement, therapeutic effect, and disease process.

Studies suggest that abnormalities in glutamate and GABA signaling contribute to deficits in schizophrenia and related conditions and that these neurochemical abnormalities produce changes in electroencephalographic (EEG) indices, including event-related potentials and event-related power within specific frequency ranges. Furthermore, clinical studies suggest that a subset of EEG biomarkers is associated with symptoms. This review addresses the relationship between EEG and behavior in preclinical models of N-methyl-d-aspartate (NMDA)-receptor hypofunction, as well as how these models can be used to screen therapies. Data from schizophrenia patients are juxtaposed with data from animal models, and EEG and behavioral data from mice with disruption of NMDA receptors in excitatory and/or inhibitory neurons are then compared to the pattern observed in schizophrenia. Also discussed are results following exposure to potential therapeutic agents, including GABAB agonists. Furthermore, evidence demonstrates that elevated resting gamma power is associated with deficits in social interactions. Consistent with elevated baseline noise, excitatory neurons from transgenic mice show increased intrinsic excitability in in vitro-slice patch-clamp studies across model systems. GABAB receptor agonists reduce this excitability, improve gamma-band responses, and reverse behavioral deficits in mice. Data suggest that baseline gamma power is associated with social function and GABAB agonists may be useful for schizophrenia. Translational EEG biomarkers reflect target engagement and can contribute to the design of more efficient drug trials, likely accelerating the development of new therapeutics for central nervous system disorders.