Biology subjects

Jentsch, T. J.

Publications and source records attributed to Jentsch, T. J..

4 recordsLinked to original sources

bioRxiv2025

Structural basis of ClC-3 inhibition by TMEM9 and PI(3,5)P2

The trafficking and activity of endosomes relies on the exchange of chloride ions and protons by members of the CLC family of chloride channels and transporters, whose mutations are associated with numerous diseases. Despite their critical roles, the mechanisms by which CLC transporters are regulated are poorly understood. Here, we show that two related accessory {beta}-subunits, TMEM9 and TMEM9B, directly interact with ClC-3, -4 and -5. Cryo-EM structures reveal that TMEM9 inhibits ClC-3 by sealing the cytosolic entrance to the Cl- ion pathway. Unexpectedly, we find that PI(3,5)P2 stabilizes the interaction between TMEM9 and ClC-3 and is required for proper regulation of ClC-3 by TMEM9. Collectively, our findings reveal that TMEM9 and PI(3,5)P2 collaborate to regulate endosomal ion homeostasis by modulating the activity of ClC-3.

cell biology↗

bioRxiv2024

Renal proximal tubules are sensitive to metabolic acidosis

Patients suffering from distal renal tubular acidosis (dRTA) are sometimes diagnosed with proximal tubule dysfunction with leaks of phosphate, uric acid, amino acids, and low-molecular-weight proteins, also known as Fanconi-like syndrome. The underlying molecular basis is largely elusive. We previously reported on Atp6v0a4 knockout (KO) mice, which exhibit severe metabolic acidosis in combination with proximal tubule dysfunction as evidenced by phosphaturia and proteinuria. Here, we show that Rab7, a key regulator of endo-lysosomal trafficking and lysosomal biogenesis, is strongly diminished in proximal tubules of Atp6v0a4 KO mice, while the number of abnormal Ist1-labelled Lamp1-positive vesicles is increased. This is accompanied by the accumulation of autophagosomes, autolysosomes and autophagic substrates. Importantly, correction of metabolic acidosis with bicarbonate therapy resolves proximal tubule dysfunction and trafficking defects in Atp6v0a4 KO mice. Acid-challenged wildtype mice also show trafficking defects with Rab7-downregulation and an increase in Ist1-labeled Lamp1-positive vesicles and develop proximal tubule damage in the long-term. Similar acidosis-induced alterations also occur in human kidney organoids. Altogether, our data provide insights, why patients suffering from severe dRTA may develop a Fanconi-like syndrome, which may contribute to the progression of chronic kidney failure. Translational StatementPatients with renal acidosis caused by impaired proton secretion in the collecting duct (distal renal tubular acidosis - dRTA) sometimes show unexplained symptoms of proximal tubule dysfunction such as proteinuria and phosphaturia. Here, we show that proximal tubules are particularly sensitive to acidosis as evidenced by impaired trafficking, lysosomal damage and accumulation of autophagic substrates. We also show that early treatment of dRTA by alkali supplementation can prevent proximal tubule dysfunction. Because metabolic acidosis represents a well-known risk factor for the progression of chronic kidney disease (CKD), our findings highlight the potential clinical importance of early alkali supplementation to delay disease progression.

molecular biology↗

bioRxiv2023

KCNQ5 controls perivascular adipose tissue-mediated vasodilation

BackgroundSmall arteries exhibit resting tone, a partially contracted state that maintains arterial blood pressure. In arterial smooth muscle cells (SMCs), potassium channels control contraction and relaxation. Perivascular adipose tissue (PVAT) has been shown to exert anticontractile effects on the blood vessels. However, the mechanisms by which PVAT signals small arteries, and their relevance, remain largely unknown. We aimed to uncover key molecular components in adipose-vascular coupling. MethodsA wide-spectrum of genetic mouse models targeting Kcnq3, Kcnq4 and Kcnq5 genes (Kcnq3-/-, Kcnq4-/-, Kcnq5-/-, Kcnq5dn/dn, Kcnq4-/-/Kcnq5dn/dn, Kcnq4-/-/Kcnq5-/-), telemetry blood pressure measurements, targeted lipidomics, and RNA-Seq profiling, wire-myography, patch-clamp, and sharp-electrode membrane potential measurements were used. ResultsWe show that PVAT causes SMC KCNQ5 (KV7.5) channels to hyperpolarize the membrane potential. This effect relaxes small arteries and regulates blood pressure. Oxygenation of polyunsaturated fats generates oxylipins, a superclass of lipid mediators. We identified numerous oxylipins released by PVAT that potentiate vasodilatory action in small arteries by opening SMC KCNQ5 channels. ConclusionsOur results reveal a key molecular function of KCNQ5 channels in adipose-vascular coupling, translating PVAT signals, particularly oxylipins, to the central physiological function of vasoregulation. This novel pathway opens new therapeutic perspectives.

physiology↗

bioRxiv2019

Identification of TMEM206 proteins as pore of ASOR acid-sensitive chloride channels

Acid-sensing ion channels have important functions in physiology and pathology, but the molecular composition of acid-activated anion channels had remained unclear. We now used a genome-wide siRNA screen to molecularly identify the widely expressed acid-sensitive outwardly-rectifying ASOR chloride channel. ASOR is formed by TMEM206 proteins which display two transmembrane domains (TMs) and are expressed at the plasma membrane. Ion permeation-changing mutations along the length of TM2 and at the end of TM1 suggest that these segments line ASORs pore. While not belonging to a gene family, TMEM206 has orthologs in probably all vertebrates. Currents from evolutionarily distant orthologs share activation by protons, a feature essential for ASORs role in acid-induced cell death. TMEM206 defines a novel class of ion channels. Its identification will help to understand its physiological roles and the diverse ways by which anion-selective pores can be formed.

physiology↗