PDE4C (phosphodiesterase 4C; HGNC:8782, NCBI Gene ID 5143) is a human locus mapped to chromosome band 19p13.11 that encodes cAMP-specific 3-prime,5-prime-cyclic phosphodiesterase 4C isoforms PDE4C1–PDE4C3 (712 aa; EC 3.1.4.53). PDE4C acts in renal primary cilium AKAP9-PKD1/PKD2-PDE4C local cAMP degradation (suppressing renal cystogenesis) & top pan-tissue Horvath/Weidner DNA-methylation aging clock locus, together with PDE4A (Paralog on Chromosome 19p13.2), PDE4B (Immune & Striatal Paralog Gene), and PDE4D (Hippocampal & Cardiac Paralog Gene). Encodes cAMP-specific phosphodiesterase 4C, which localizes to renal primary cilia to restrain cystogenesis and harbors the most reproducible CpG methylation biomarker of human chronological aging.
Renal primary cilium AKAP9-PKD1/PKD2-PDE4C local cAMP degradation (suppressing renal cystogenesis) & top pan-tissue Horvath/Weidner DNA-methylation aging clock locus
Clinical / Therapeutic Role
Ciliary loss accelerates autosomal dominant polycystic kidney disease (ADPKD); CpG site cg17861230 in PDE4C is the single strongest single-locus predictor of chronological human age
Gene Structure & Expression
Genomic Organization & Cytogenetic Locus: 16-exon gene on chromosome 19p13.11 containing a prominent CpG island across exon 1 / intron 1 that undergoes linear, clock-like hypermethylation from birth to centenarian age across virtually all human nucleated blood and solid tissues.
Cellular & Tissue Expression Profile: Showcases the most tissue-restricted expression profile of the four PDE4 family members: concentrated in the primary cilia of renal tubular epithelial cells, pulmonary airway epithelium, testicular spermatogenic cells, and pancreatic islet beta cells, with minimal expression in circulating leukocytes or brainstem emetic centers.
Molecular Function & Pathways
Biochemical & Physiological Mechanism: In renal tubular epithelial cells, the hepatocyte nuclear factor-1beta (HNF1B) transcriptionally activates PDE4C, and the encoded enzyme is targeted to the primary cilium by the A-kinase anchoring protein AKAP9 (AKAP450), where it forms a macromolecular signaling complex with polycystin-1 (PKD1) and polycystin-2 (PKD2); by continuously hydrolyzing ciliary cAMP, PDE4C prevents PKA-driven chloride fluid secretion (via CFTR) and B-Raf-ERK cell proliferation that drive renal cyst expansion.
Clinical & Therapeutic Significance
Human Genetic Variants & Disease Phenotypes: Loss of PKD1, PKD2, or HNF1B disrupts ciliary PDE4C localization, causing the pathogenic cAMP surge that drives Autosomal Dominant Polycystic Kidney Disease (ADPKD); independently, in human epigenomics and forensic medicine, the CpG dinucleotide cg17861230 in PDE4C alone correlates with chronological age at R2 > 0.85 across blood, saliva, and somatic tissues (Weidner 3-CpG and Horvath epigenetic clocks).
Therapeutic & Clinical Pharmacology: Allosteric activators of long PDE4 isoforms (such as MR-L2 and compound 3144, which mimic PKA phosphorylation of UCR1) lower renal cAMP and inhibit cyst growth in preclinical polycystic kidney disease models.