ADCY8

Membrane adenylyl cyclase AC8 is regulated by G proteins and calmodulin (CaM), mediating the crosstalk between the cAMP pathway and Ca²⁺ signalling. Despite the importance of AC8 in physiology, the structural basis of its regulation by G proteins and CaM is not well defined. Here, we report the 3.5 Å resolution cryo-EM structure of the bovine AC8 bound to the stimulatory Gαs protein in the presence of Ca²⁺/CaM. The structure reveals the architecture of the ordered AC8 domains bound to Gαs and the small molecule activator forskolin. The extracellular surface of AC8 features a negatively charged pocket, a potential site for unknown interactors. Despite the well-resolved forskolin density, the captured state of AC8 does not favour tight nucleotide binding. The structural proteomics approaches, limited proteolysis and crosslinking mass spectrometry (LiP-MS and XL-MS), allowed us to identify the contact sites between AC8 and its regulators, CaM, Gαs, and Gβγ, as well as to infer the conformational changes induced by these interactions. Our results provide a framework for understanding the role of flexible regions in the mechanism of AC regulation.

We examined the 12-month maintenance effects of a previously successful integrated model of diabetes care at improving glycemic management and psychological well-being among Latino adults with type 2 diabetes (T2D). A randomized controlled trial (2015-19) compared an integrated care intervention (ICI) with usual care among 456 adults with T2D. The ICI included integrated medical and behavioral care and health education over 6 months. Assessments were completed at baseline, 3, 6, 9, and 12 months. Most participants were female (63.7%) with a mean age of 55.7 years. In multilevel models, significant Group × Time (quadratic) interaction effects were found for HbA1c [Bint = 0.10, 95% confidence interval (CI) 0.02, 0.17, P < .01] and anxiety symptoms (Bint = 0.20, 95% CI 0.05, 0.35, P < .009), but not depression symptoms (Bint = 0.15, 95% CI -0.01, 0.31, P < .07). Analyses of instantaneous rate of change in the ICI group showed significant decreases at 3 and 6 months for both HbAc1 (B = -0.31 at 3 months; B = -0.12 at 6 months) and anxiety symptoms (B = -0.92 at 3 months; B = -0.46 at 6 months), and no significant instantaneous changes at 9 or 12 months, suggesting that initial improvements were largely maintained. The usual care group showed a small decrease in anxiety symptoms at 6 months (B = -0.17), but no other significant changes at any time-point for anxiety or HbA1c (all Ps > .05). This culturally tailored integrated care model shows potential in producing and sustaining positive effects on clinical and psychological outcomes above standard care.

The upregulation of Orai1 and subsequent store-operated Ca²⁺ entry (SOCE) has been associated with adverse cardiac remodeling and heart failure (HF). However, the mechanism underlying Orai1 upregulation and its role in myocardial infarction remains unclear. Our study investigated the role of Orai1 in activating adenylyl cyclase 8 (AC8) and cAMP response element-binding protein (CREB), as well as its contribution to cardiac dysfunction induced by ischemia and reperfusion (I/R). We found that I/R evoked an increase in the expression of Orai1 and AC8 in rats' hearts, resulting in a substantial rise in diastolic Ca²⁺ concentration ([Ca²⁺]_i), and reduced ventricular contractions. The expression of Orai1 and AC8 was also increased in ventricular biopsies of post-ischemic HF patients. Mechanistically, we demonstrate that I/R activation of Orai1 stimulated AC8, which produced cAMP and phosphorylated CREB. Subsequently, p-CREB activated the ORAI1 promoter, resulting in Orai1 upregulation and SOCE exacerbation. Intramyocardial administration of AAV9 carrying AC8 shRNA decreased the expression of AC8, Orai1 and CREB, which restored diastolic [Ca²⁺]_i and improved cardiac contraction. Therefore, our data suggests that the axis composed by Orai1/AC8/CREB plays a critical role in I/R-induced cardiac dysfunction, representing a potential new therapeutic target to limit the progression of the disease towards HF.