Adenylyl cyclase 7 and neuropsychiatric disorders: A new target for depression?

Functional and pathological roles of adenylyl cyclases in various diseases

Adenylyl cyclases (ADCYs) produce the second messengers cAMP, which is crucial for a number of cellular activities. There are ten isoforms in the mammalian ADCY family including nine transmembrane adenylyl cyclases (tmAC) and one soluble adenylyl cyclase (sAC/ADCY10). There have been numerous studies demonstrating the importance of ADCYs in the development of a wide range of diseases, including cardiovascular disease, neurological disease, liver disease, and tumors. The classification, structure and regulation of ADCYs are discussed in this overview, which is followed by an analysis of how ADCYs are involved in various disorders and how they are used as a therapeutic tool. Our objective is to get a more thorough understanding of ADCYs to aid future study and provide novel ideas for the treatment of particular diseases.

ADCY7 mRNA Is a Novel Biomarker in HPV Infection and Cervical High-Grade Squamous Lesions or Higher

The effect of cervical cancer immunotherapy is limited. Combination therapy will be a new direction for cervical cancer. Thus, it is essential to discover a novel and available predictive biomarker to stratify patients who may benefit from immunotherapy for cervical cancer. In this study, 563 participants were enrolled. Adenylate cyclase 7 (ADCY7) mRNA was detected by real-time quantitative PCR (qPCR) with cervical cytology specimens. The relationship between ADCY7 and cervical intraepithelial neoplasia in grade 2 and higher (CIN2+) was analyzed, and the optimal cut-off values of the relative expression of ADCY7 mRNA to predict CIN2+ were calculated. In addition, the clinical significance of ADCY7 in cervical cancer was determined by the Kaplan–Meier Cox regression based on the TCGA database. The mean ADCY7 mRNA expression increased significantly with cervical lesion development, especially compared with CIN2+ (p < 0.05). Moreover, the expression of ADCY7 increased significantly in high-risk human papillomavirus (HR-HPV) infection but not in HPV-A5/6 species. The area under the receiver operating characteristic curve (AUC) of ADCY7 was 0.897, and an optimal cut-off was 0.435. Furthermore, ADCY7 had the highest OR (OR= 8.589; 95% CI (2.281–22.339)) for detecting CIN 2+, followed by HPV genotyping, TCT, and age (OR = 4.487, OR = 2.071, and OR = 1.345; 95% CI (1.156–10.518), (0.370–8.137), and (0.171–4.694), respectively). Moreover, this study indicated that higher ADCY7 levels could be a suitable predictor for poor prognosis in cervical cancer due to immune cell infiltration. A new auxiliary predictor of CIN2+ in cervical cytology specimens is ADCY7 ≥ 0.435. Furthermore, it may be a promising prognosis predictor and potential immunotherapy target for the combined treatment of cervical cancer and possibly further block HR-HPV persistent infection.

Gαs, adenylyl cyclase, and their relationship to the diagnosis and treatment of depression

The relationship between depression, its etiology and therapy, and the cAMP signaling system have been studies for decades. This review will focus on cAMP, G proteins and adenylyl cyclase and depression or antidepressant action. Both human and animal studies are compared and contrasted. It is concluded that there is some synteny in the findings that cAMP signaling is attenuated in depression and that this is reversed by successful antidepressant therapy. The G protein that activates adenylyl cyclase, Gα_s, appears to have diminished access to adenylyl cyclase in depression, and this is rectified by successful antidepressant treatment. Unfortunately, attempts to link specific isoforms of adenylyl cyclase to depression or antidepressant action suffer from discontinuity between human and animal studies.

The role of the type 7 adenylyl cyclase isoform in alcohol use disorder and depression

The translation of extracellular signals to intracellular responses involves a number of signal transduction molecules. A major component of this signal transducing function is adenylyl cyclase, which produces the intracellular "second messenger," cyclic AMP. What was initially considered as a single enzyme for cyclic AMP generation is now known to be a family of nine membrane-bound enzymes, and one cytosolic enzyme. Each member of the adenylyl cyclase family is distinguished by factors that modulate its catalytic activity, by the cell, tissue, and organ distribution of the family members, and by the physiological/behavioral functions that are subserved by particular family members. This review focuses on the Type 7 adenylyl cyclase (AC7) in terms of its catalytic characteristics and its relationship to alcohol use disorder (AUD, alcoholism), and major depressive disorder (MDD). AC7 may be part of the inherited system predisposing an individual to AUD and/or MDD in a sex-specific manner, or this enzyme may change in its expression or activity in response to the progression of disease or in response to treatment. The areas of brain expressing AC7 are related to responses to stress and evidence is available that CRF1 receptors are coupled to AC7 in the amygdala and pituitary. Interestingly, AC7 is the major form of the cyclase contained in bone marrow-derived cells of the immune system and platelets, and in microglia. AC7 is thus, poised to play an integral role in both peripheral and brain immune function thought to be etiologically involved in both AUD and MDD. Both platelet and lymphocyte adenylyl cyclase activity have been proposed as markers for AUD and MDD, as well as prognostic markers of positive response to medication for MDD. We finish with consideration of paths to medication development that may selectively modulate AC7 activity as treatments for MDD and AUD.

Physiological roles of mammalian transmembrane adenylyl cyclase isoforms

Adenylyl cyclases (ACs) catalyze the conversion of ATP to the ubiquitous second messenger cAMP. Mammals possess nine isoforms of transmembrane ACs, dubbed AC1-9, that serve as major effector enzymes of G protein-coupled receptors (GPCRs). The transmembrane ACs display varying expression patterns across tissues, giving the potential for them to have a wide array of physiological roles. Cells express multiple AC isoforms, implying that ACs have redundant functions. Furthermore, all transmembrane ACs are activated by Gαs, so it was long assumed that all ACs are activated by Gαs-coupled GPCRs. AC isoforms partition to different microdomains of the plasma membrane and form prearranged signaling complexes with specific GPCRs that contribute to cAMP signaling compartments. This compartmentation allows for a diversity of cellular and physiological responses by enabling unique signaling events to be triggered by different pools of cAMP. Isoform-specific pharmacological activators or inhibitors are lacking for most ACs, making knockdown and overexpression the primary tools for examining the physiological roles of a given isoform. Much progress has been made in understanding the physiological effects mediated through individual transmembrane ACs. GPCR-AC-cAMP signaling pathways play significant roles in regulating functions of every cell and tissue, so understanding each AC isoform's role holds potential for uncovering new approaches for treating a vast array of pathophysiological conditions.

Expression and functions of adenylyl cyclases in the CNS

Adenylyl cyclases (ADCYs), by generating second messenger cAMP, play important roles in various cellular processes. Their expression, regulation and functions in the CNS, however, remain largely unknown. In this review, we first introduce the classification and structure of ADCYs, followed by a discussion of the regulation of mammalian ADCYs (ADCY1-10). Next, the expression and function of each mammalian ADCY isoform are summarized in a region/cell-specific manner. Furthermore, the effects of GPCR-ADCY signaling on blood-brain barrier (BBB) integrity are reviewed. Last, current challenges and future directions are discussed. We aim to provide a succinct review on ADCYs to foster new research in the future.

An osteoarthritis subtype characterized by synovial lipid metabolism disorder and fibroblast-like synoviocyte dysfunction

Background

The heterogeneity of osteoarthritis (OA) significantly limits the effectiveness of pharmacological treatments in an unselected patient population. In this context, the identification of OA subtypes is meaningful for the development of therapies that target specific types of OA pathogenesis.

Methods

Expression array profiles of 70 OA and 36 control synovial samples were extracted from the GEO database. Unsupervised consensus clustering was performed based on the most variable genes to identify OA subclusters. Next, Joint samples from OA patients were obtained. We divided the OA patient into two subpopulations according to synovial ADCY7 levels. Synovium and cartilage samples from different OA subpopulations were evaluated. In addition, we established a high-fat diet (HFD)-induced rat OA model. We evaluated OA progression, lipid metabolism, synovitis and fibroblast-like synoviocytes (FLS) function in this HFD-induced OA model.

Results

70 OA patients were categorized into three distinct subclusters. We noted that one subcluster was characterized by synovial lipid metabolism disorder GO terms. We further identified the most noticeable KEGG pathway “Regulation of lipolysis in adipocytes” in this subcluster as well as the most significantly differentially expressed gene, ADCY7. We found that the ADCY7 high expressing group (32.6%) exhibited features of synovial inflammatory lipolysis epithelial-mesenchymal transition (EMT) tendency, as well as faster join space narrowing. The HFD induced OA-like degeneration in rat joints. We observed similar synovial inflammatory lipolysis and EMT in FLS, characterized by higher proliferative and invasive activity and elevated proinflammatory and procatabolic properties. ADCY7 was highly expressed in the synovium of the HFD-OA model rats and the inhibition of ADCY7 effectively attenuated these HFD-induced degenerative changes as well as synovial inflammatory lipolysis and FLS dysfunction. In HFD-FLSs, ADCY7 promoted the phosphorylation of PKA as well as its downstream lipid droplet-associated protein PLIN1 and hormone-sensitive lipase (HSL). The inhibition of PKA largely alleviated ADCY7-mediated HFD-FLS dysfunction.

Conclusions

We described a synovial EMT and lipid metabolism disorder in the pathogenesis of OA. This novel mechanism may represent a currently undefined OA subtype. ADCY7 is a potential molecular marker of this pathomechanism.

The Translational potential of this article

Utilizing synovial samples from OA patients, we identified a subpopulation with high ADCY7 expression. This may represent a currently undefined OA subtype and explain the clinical phenomenon of more severe synovial inflammation in obese OA patients. In addition, we established an HFD-induced OA rat model and found an upregulation of ADCY7 in the synovium. We confirmed that the inhibition of ADCY7 could effectively attenuate HFD-induced degenerative changes as well as the inflammatory lipolysis and FLS dysfunction observed in the rat model. This suggests that ADCY7 and its downstream pathways are potential pharmacological targets for treating this lipid-metabolism-disorder-related OA mechanism.

A Pan-Cancer Analysis of the Prognostic Value and Expression of Adenylate Cyclase 7 (ADCY7) in Human Tumors

BACKGROUND

The role of adenylate cyclase 7 (ADCY7) in cancer is still unclear. This study analyzed the interrelationship between the expression and immune function of ADCY7.

METHODS

ADCY7 expression in multiple human cancers was analyzed using the databases of Genotype-Tissue Expression Project (GTEx), Cancer Cell Line Encyclopedia (CCLE), and The Cancer Genome Atlas (TCGA). Correlations among ADCY7 gene expression, mismatch repair (MMR) gene expression, and DNA methyltransferase (DNMT) expression were assessed using Spearman correlation analysis. Univariate survival analysis and Kaplan-Meier (KM) curve were used to examine the effect of ADCY7 expression on prognosis. The Tumor Immune Estimation Resource (TIMER) database was used to evaluate the relationship between ADCY7 gene expression and tumor immune invasion or immune checkpoint gene (ICG) expression.

RESULTS

ADCY7 was abnormally expressed in multiple human cancers and was correlated with MMR genes and DNMT expression. Univariate survival analysis and KM curve showed that ADCY7 expression influences the overall survival (OS) of six types of cancer, disease-specific survival (DSS) of eight, and progression-free interval (PFI) of three. The high expression of ADCY7 in OS, DSS, and PFI was strongly associated with poor outcomes in patients with breast cancer and lung squamous cell carcinoma. ADCY7 expression was strongly associated with immune cell infiltration and ICG expression.

CONCLUSION

The results of this study indicated that ADCY7 may be a prognostic biomarker of tumorigenesis. The study may also provide a new perspective on the role of ADCY7 in human cancers.

Cross-Talk Between the Adenylyl Cyclase/cAMP Pathway and Ca2+ Homeostasis

Cyclic AMP and Ca²⁺ are the first second or intracellular messengers identified, unveiling the cellular mechanisms activated by a plethora of extracellular signals, including hormones. Cyclic AMP generation is catalyzed by adenylyl cyclases (ACs), which convert ATP into cAMP and pyrophosphate. By the way, Ca²⁺, as energy, can neither be created nor be destroyed; Ca²⁺ can only be transported, from one compartment to another, or chelated by a variety of Ca²⁺-binding molecules. The fine regulation of cytosolic concentrations of cAMP and free Ca²⁺ is crucial in cell function and there is an intimate cross-talk between both messengers to fine-tune the cellular responses. Cancer is a multifactorial disease resulting from a combination of genetic and environmental factors. Frequent cases of cAMP and/or Ca²⁺ homeostasis remodeling have been described in cancer cells. In those tumoral cells, cAMP and Ca²⁺ signaling plays a crucial role in the development of hallmarks of cancer, including enhanced proliferation and migration, invasion, apoptosis resistance, or angiogenesis. This review summarizes the cross-talk between the ACs/cAMP and Ca²⁺ intracellular pathways with special attention to the functional and reciprocal regulation between Orai1 and AC8 in normal and cancer cells.

Biased Ligands at the Kappa Opioid Receptor: Fine-Tuning Receptor Pharmacology

The kappa opioid receptor (KOR) is a G protein-coupled receptor (GPCR) that can signal through multiple signaling pathways. KOR agonists are known to relieve pain and itch, as well as induce dysphoria, sedation, hallucinations, and diuresis. As is the case with many other GPCRs, specific signaling pathways downstream of the KOR have been linked to certain physiological responses induced by the receptor. Those studies motivated the search and discovery of a number of KOR ligands that preferentially activate one signaling pathway over another. Such compounds are termed functionally selective or biased ligands, and may present a way of inducing desired receptor effects with reduced adverse reactions. In this chapter, I review the molecular intricacies of KOR signaling and discuss the studies that have used biased signaling through the KOR as a way to selectively modulate in vivo physiology.