South Korean researchers have uncovered a sophisticated molecular mechanism in the kidneys that regulates water reabsorption, helping the body maintain hydration and guard against dehydration.
A research team led by Professor Jeong Hyun-joon of the Biomedical Research Institute at Kyungpook National University Hospital and Professor Kwon Tae-hwan of the Kyungpook National University School of Medicine announced on Sept. 18 that they identified the precise process by which antidiuretic hormone selectively activates specific genes within kidney cells.
The study was published in the prestigious international journal Proceedings of the National Academy of Sciences of the United States of America (PNAS).
Antidiuretic hormone instructs the kidneys to reabsorb water whenever body fluid levels drop. Acting on principal cells in the kidney's collecting ducts—the final passageway before urine is excreted—the hormone increases water permeability and concentrates urine to preserve the body's fluid balance.
The research team focused on the gene-regulatory pathway triggered inside these cells when antidiuretic hormone acts on the kidneys. They discovered that upon receiving the hormonal signal, key intracellular proteins—including TRIM28 and CDK9—assemble around the protein beta-catenin (CTNNB1) to form a unified gene-regulation complex.
This protein complex controls the activity of RNA polymerase II, the enzymatic machinery responsible for transcribing genetic blueprints. Serving as the master scaffold, beta-catenin connects multiple proteins and alters chromatin structure, ensuring that only specific genes responsive to antidiuretic hormone—such as the aquaporin-2 (AQP2) water channel gene—are selectively activated.
By identifying this molecular operating principle, the study clearly demonstrates how the kidneys conserve water at the cellular level when fluid intake decreases or sweating increases. Beyond describing a simple hormonal response, the discovery provides a fundamental framework for how kidney cells switch targeted genes on and off.
The findings are expected to serve as vital foundational data for developing novel therapeutics for kidney disorders caused by impaired water regulation, including diabetes insipidus, a condition characterized by excessive urine production.
The study was supported by the Ministry of Health and Welfare and the Korea Health Industry Development Institute’s regional medical research capacity enhancement program, the Ministry of Science and ICT and the Ministry of Education’s Mid-Career Researcher Support Program, the Basic Medical Science Research Center, the Next-Generation Scholar Support Program, and the BK21 FOUR program. Dr. Jang Hyo-joo participated as the lead author, with Research Professor Park Ui-jeong serving as co-author.
