Lithium Causes G2 Arrest of Renal Principal Cells

• Published in: Journal of the American Society of Nephrology 2014-03, Vol.25 (3), p.501-510
• Main Authors: DE GROOT, Theun, ALSADY, Mohammad, JAKLOFSKY, Marcel, OTTE-HÖLLER, Irene, BAUMGARTEN, Ruben, GILES, Rachel H, DEEN, Peter M. T
• Format: Article
• Language: English
• Subjects: Animals; Antimanic Agents - adverse effects; Basic Research; Biological and medical sciences; Cell Proliferation - drug effects; Checkpoint Kinase 1; Diabetes Insipidus, Nephrogenic - chemically induced; Diabetes Insipidus, Nephrogenic - enzymology; Female; G2 Phase Cell Cycle Checkpoints - drug effects; Lithium - adverse effects; Male; Medical sciences; Mice; Mice, Inbred C57BL; Nephrology. Urinary tract diseases; Protein Kinases - metabolism
• ISSN: 1046-6673; 1533-3450
• DOI: 10.1681/ASN.2013090988

Vasopressin-regulated expression and insertion of aquaporin-2 channels in the luminal membrane of renal principal cells is essential for urine concentration. Lithium affects urine concentrating ability, and approximately 20% of patients treated with lithium develop nephrogenic diabetes insipidus (NDI), a disorder characterized by polyuria and polydipsia. Lithium-induced NDI is caused by aquaporin-2 downregulation and a reduced ratio of principal/intercalated cells, yet lithium induces principal cell proliferation. Here, we studied how lithium-induced principal cell proliferation can lead to a reduced ratio of principal/intercalated cells using two-dimensional and three-dimensional polarized cultures of mouse renal collecting duct cells and mice treated with clinically relevant lithium concentrations. DNA image cytometry and immunoblotting revealed that lithium initiated proliferation of mouse renal collecting duct cells but also increased the G2/S ratio, indicating G2/M phase arrest. In mice, treatment with lithium for 4, 7, 10, or 13 days led to features of NDI and an increase in the number of principal cells expressing PCNA in the papilla. Remarkably, 30%-40% of the PCNA-positive principal cells also expressed pHistone-H3, a late G2/M phase marker detected in approximately 20% of cells during undisturbed proliferation. Our data reveal that lithium treatment initiates proliferation of renal principal cells but that a significant percentage of these cells are arrested in the late G2 phase, which explains the reduced principal/intercalated cell ratio and may identify the molecular pathway underlying the development of lithium-induced renal fibrosis.