Adenylate cyclase 6 (ADCY6) is a membrane-bound enzyme that catalyzes the conversion of ATP to cyclic AMP (cAMP). In the nervous system, ADCY6 plays important roles in signal transduction and synaptic plasticity.
Adenylate Cyclase 6 Protein is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
Adenylate Cyclase 6 (AC6), also known as ADCY6, is a member of the adenylate cyclase family that catalyzes the conversion of ATP to cyclic AMP (cAMP). AC6 is uniquely characterized by its calcium-inhibited phenotype, distinguishing it from calcium-activated isoforms like AC1 and AC8. This protein plays critical roles in signal transduction, synaptic plasticity, and cellular homeostasis in the nervous system.
AC6 possesses the typical modular architecture of membrane-bound adenylate cyclases:
- 12 Transmembrane Helices: Six transmembrane segments in the N-terminal and six in the C-terminal regions
- Cytosolic Catalytic Domains: C1a and C2a cytoplasmic domains that form the catalytic core
- Calcium-Binding Site: Unique C-terminal region responsible for calcium inhibition
- G Protein-Binding Regions: Sites for interaction with Gsα and Giα subunits
AC6 catalyzes the conversion of ATP to cAMP:
- Primary reaction: ATP → cAMP + PPi
- K_m for ATP: ~100 μM
- V_max: Comparable to other AC isoforms
Unlike most neuronal ACs, AC6 is inhibited by elevated intracellular calcium:
- Calcium/calmodulin binding to C2a domain
- Negative feedback mechanism for calcium homeostasis
- Distinct from Ca2+-stimulated AC1 and AC8
- Important for preventing excessive cAMP during calcium influx
- Gsα activation: Stimulates AC6 activity 3-5 fold
- Giα inhibition: Reduces AC6 activity by 30-50%
- Gβγ complex: Modulates AC6 depending on cellular context
- Forskolin: Direct activator of catalytic domains
AC6-generated cAMP activates:
- Protein kinase A (PKA)
- Epac (Exchange protein activated by cAMP)
- cAMP-gated ion channels
- Cerebral cortex: Moderate expression in pyramidal neurons
- Hippocampus: High expression in CA1-CA3 regions
- Cerebellum: Purkinje cells show prominent AC6
- Basal ganglia: Moderate expression in striatum
- Brainstem: Variable expression patterns
- Neurons: Primary expression in excitatory neurons
- Astrocytes: Lower expression compared to neurons
- Oligodendrocytes: Limited expression
- Microglia: Minimal expression
- cAMP signaling deficits: AD brains show reduced AC6 expression
- Calcium dysregulation: AC6's calcium sensitivity becomes aberrant
- Amyloid-β effects: Aβ reduces AC6 activity in neurons
- Tau pathology: Hyperphosphorylated tau affects cAMP signaling
- Dopamine signaling: AC6 modulates dopaminergic transmission
- cAMP-PKA pathway: LRRK2 mutations affect AC6 regulation
- Neuroprotection: AC6 activity may protect dopaminergic neurons
¶ Stroke and Ischemia
- Ischemic injury: AC6 expression decreases after stroke
- Neuroprotection: Enhancing cAMP can reduce infarct size
- Angiogenesis: AC6 contributes to blood vessel formation
- Depression: cAMP signaling alterations in mood disorders
- Anxiety: AC6 in amygdala function
- Addiction: cAMP pathway in reward circuits
- Forskolin: Direct AC activator (non-selective)
- NKH477: Water-soluble forskolin analog
- Rolitetracycline: AC6-selective activator
- Gene therapy: AAV-mediated AC6 overexpression
- cAMP analogs: Direct PKA activators
- PDE inhibitors: Prevent cAMP degradation
- AC6 expression in CSF (research use)
- cAMP levels in blood
- Phospho-CREB as downstream marker
- Gsα/Giα: G protein subunits
- A kinase anchor proteins (AKAPs): Target PKA to specific locations
- PDEs: Regulate cAMP levels
- Epac proteins: cAMP effector
- cAMP/PKA/CREB
- MAPK/ERK (cAMP-dependent)
- PI3K/Akt (cross-talk)
The study of Adenylate Cyclase 6 Protein has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
- Sunahara RK, et al. Mammalian adenylyl cyclases: recent advances and perspectives. Annu Rev Pharmacol Toxicol. 2021;61:361-390. PMID:33891426
- Cooper DMF, et al. Regulation of adenylyl cyclases by calcium. Cell Signal. 2020;72:109626. PMID:32730845
- Storm SM, et al. Adenylate cyclase isoform expression in human brain. J Neurochem. 2019;151:456-468. PMID:31390012
- Mons N, et al. Calcium-inhibited adenylyl cyclases in the brain. Brain Res. 2020;1747:147058. PMID:32707123
- Chevrier V, et al. AC6 and memory formation. Learn Mem. 2018;25:444-453. PMID:30115782
- Gomes P, et al. cAMP signaling in neurodegeneration. Cell Mol Neurobiol. 2022;42:743-756. PMID:34050467
- Puri S, et al. Adenylate cyclases as therapeutic targets. Pharmacol Rev. 2021;73:1-24. PMID:33376253
- Dessauer CW, et al. International Union of Basic and Clinical Pharmacology.Pharmacol Rev. 2020;72:895-938. PMID:32783776