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Prasad H, Mandal S, Mathew JKK, Cherukunnath A, Duddu AS, Banerjee M, Ramani H, Bhat R, Jolly MK, Visweswariah SS. An Endosomal Acid-Regulatory Feedback System Rewires Cytosolic cAMP Metabolism and Drives Tumor Progression. Mol Cancer Res 2024; 22:465-481. [PMID: 38319300 DOI: 10.1158/1541-7786.mcr-23-0606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Revised: 01/02/2024] [Accepted: 02/02/2024] [Indexed: 02/07/2024]
Abstract
Although suppressed cAMP levels have been linked to cancer for nearly five decades, the molecular basis remains uncertain. Here, we identify endosomal pH as a novel regulator of cytosolic cAMP homeostasis and a promoter of transformed phenotypic traits in colorectal cancer. Combining experiments and computational analysis, we show that the Na+/H+ exchanger NHE9 contributes to proton leak and causes luminal alkalinization, which induces resting [Ca2+], and in consequence, represses cAMP levels, creating a feedback loop that echoes nutrient deprivation or hypoxia. Higher NHE9 expression in cancer epithelia is associated with a hybrid epithelial-mesenchymal (E/M) state, poor prognosis, tumor budding, and invasive growth in vitro and in vivo. These findings point to NHE9-mediated cAMP suppression as a pseudostarvation-induced invasion state and potential therapeutic vulnerability in colorectal cancer. Our observations lay the groundwork for future research into the complexities of endosome-driven metabolic reprogramming and phenotype switching and the biology of cancer progression. IMPLICATIONS Endosomal pH regulator NHE9 actively controls cytosolic Ca2+ levels to downregulate the adenylate cyclase-cAMP system, enabling colorectal cancer cells to acquire hybrid E/M characteristics and promoting metastatic progression.
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Affiliation(s)
- Hari Prasad
- Department of Developmental Biology and Genetics, Indian Institute of Science, Bengaluru, Karnataka, India
| | - Susmita Mandal
- Department of Bioengineering, Indian Institute of Science, Bengaluru, Karnataka, India
| | | | - Aparna Cherukunnath
- Department of Developmental Biology and Genetics, Indian Institute of Science, Bengaluru, Karnataka, India
| | | | - Mallar Banerjee
- Department of Developmental Biology and Genetics, Indian Institute of Science, Bengaluru, Karnataka, India
| | - Harini Ramani
- Department of Developmental Biology and Genetics, Indian Institute of Science, Bengaluru, Karnataka, India
| | - Ramray Bhat
- Department of Developmental Biology and Genetics, Indian Institute of Science, Bengaluru, Karnataka, India
- Department of Bioengineering, Indian Institute of Science, Bengaluru, Karnataka, India
| | - Mohit Kumar Jolly
- Department of Bioengineering, Indian Institute of Science, Bengaluru, Karnataka, India
| | - Sandhya S Visweswariah
- Department of Developmental Biology and Genetics, Indian Institute of Science, Bengaluru, Karnataka, India
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Gao AYL, Lourdin-De Filippis E, Orlowski J, McKinney RA. Roles of Endomembrane Alkali Cation/Proton Exchangers in Synaptic Function and Neurodevelopmental Disorders. Front Physiol 2022; 13:892196. [PMID: 35547574 PMCID: PMC9081726 DOI: 10.3389/fphys.2022.892196] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 03/30/2022] [Indexed: 12/25/2022] Open
Abstract
Endomembrane alkali cation (Na+, K+)/proton (H+) exchangers (eNHEs) are increasingly associated with neurological disorders. These eNHEs play integral roles in regulating the luminal pH, processing, and trafficking of cargo along the secretory (Golgi and post-Golgi vesicles) and endocytic (early, recycling, and late endosomes) pathways, essential regulatory processes vital for neuronal development and plasticity. Given the complex morphology and compartmentalization of multipolar neurons, the contribution of eNHEs in maintaining optimal pH homeostasis and cargo trafficking is especially significant during periods of structural and functional development and remodeling. While the importance of eNHEs has been demonstrated in a variety of non-neuronal cell types, their involvement in neuronal function is less well understood. In this review, we will discuss their emerging roles in excitatory synaptic function, particularly as it pertains to cellular learning and remodeling. We will also explore their connections to neurodevelopmental conditions, including intellectual disability, autism, and attention deficit hyperactivity disorders.
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Affiliation(s)
- Andy Y L Gao
- Integrated Program in Neuroscience, McGill University, Montreal, QC, Canada.,Department of Pharmacology & Therapeutics, McGill University, Montreal, QC, Canada
| | | | - John Orlowski
- Department of Physiology, McGill University, Montreal, QC, Canada
| | - R Anne McKinney
- Department of Pharmacology & Therapeutics, McGill University, Montreal, QC, Canada
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Ren W, Lou H, Ren X, Wen G, Wu X, Xia X, Wang S, Yu X, Yan L, Zhang G, Yao J, Lu Y, Wu X. Ketamine promotes the amyloidogenic pathway by regulating endosomal pH. Toxicology 2022; 471:153163. [PMID: 35378374 DOI: 10.1016/j.tox.2022.153163] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 03/21/2022] [Accepted: 03/22/2022] [Indexed: 10/18/2022]
Abstract
Ketamine is an anesthetic and addictive drug that can cause cognitive dysfunction and neuroinflammation. Studies have shown that carboxy-terminal fragment derived from β-secretase (CTF-β) and amyloid beta (Aβ), the amyloidogenic products of amyloid precursor protein (APP), can also induce neuroinflammation and impair cognitive function. However, it remains unclear whether ketamine regulates the amyloidogenic pathway. In the endosome, APP is cleaved by beta-site amyloid precursor protein cleaving enzyme 1 (BACE1), whose activity is influenced by pH. Endosomal acidification is mainly regulated by sodium hydrogen exchanger 6 (NHE6), which leaks protons out of endosomes, and vacuolar proton translocating ATPases (V-ATPase), which pump protons into endosomes. Therefore, we hypothesized that ketamine lowers the endosomal pH by reducing the endosomal NHE6 protein level, and this hyperacidification promotes the amyloidogenic pathway. We set up C57BL/6 J mouse models using 10, 20, 40, 80, and 100 mg/kg ketamine administration and SH-SY5Y cell models using 1, 10, 100, and 1000 μM ketamine administration to investigate its effects on the amyloidogenic pathway at different doses. Western blotting results showed that 100 mg/kg ketamine treatment in vivo and 1000 μM ketamine treatment in vitro increased endosomal BACE1 and CTF-β protein levels and reduced endosomal NHE6 and APP protein levels. The endosomal accumulation of BACE1 caused by ketamine administration was also observed using confocal imaging. Moreover, flow cytometry indicated that ketamine treatment lowered the endosomal pH value of SH-SY5Y cells. Later, cells were pretreated with monensin to restore the endosomal pH. Monensin did not affect amyloidogenic-related proteins or NHE6 directly; therefore, ketamine-promoted endosomal amyloidogenic processing and BACE1 accumulation were depleted by restoring endosomal acidity through monensin pretreatment. Finally, knockdown of NHE6 promoted the amyloidogenic pathway similarly and prevented further enhancement by ketamine. These results indicated that the effects of ketamine on the amyloidogenic pathway were dependent on the reduction of NHE6 and endosomal pH.
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Affiliation(s)
- Weishu Ren
- School of Forensic Medicine, China Medical University, Shenyang, China
| | - Haoyang Lou
- School of Forensic Medicine, China Medical University, Shenyang, China
| | - Xinghua Ren
- School of Forensic Medicine, China Medical University, Shenyang, China
| | - Gehua Wen
- School of Forensic Medicine, China Medical University, Shenyang, China
| | - Xue Wu
- School of Forensic Medicine, China Medical University, Shenyang, China
| | - Xi Xia
- School of Forensic Medicine, China Medical University, Shenyang, China
| | - Shuying Wang
- Department of Anesthesiology, the First Affiliated Hospital, China Medical University, Shenyang, China
| | - Xiaojin Yu
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Lei Yan
- School of Forensic Medicine, China Medical University, Shenyang, China
| | - Guohua Zhang
- School of Forensic Medicine, China Medical University, Shenyang, China
| | - Jun Yao
- School of Forensic Medicine, China Medical University, Shenyang, China.
| | - Yan Lu
- Key Laboratory of Health Ministry in Congenital Malformation, Affiliated Shengjing Hospital of China Medical University, Shenyang, China.
| | - Xu Wu
- School of Forensic Medicine, China Medical University, Shenyang, China.
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Prasad H. Protons to Patients: targeting endosomal Na + /H + exchangers against COVID-19 and other viral diseases. FEBS J 2021; 288:5071-5088. [PMID: 34490733 PMCID: PMC8646450 DOI: 10.1111/febs.16163] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 08/10/2021] [Accepted: 08/23/2021] [Indexed: 12/15/2022]
Abstract
While there is undeniable evidence to link endosomal acid‐base homeostasis to viral pathogenesis, the lack of druggable molecular targets has hindered translation from bench to bedside. The recent identification of variants in the interferon‐inducible endosomal Na+/H+ exchanger 9 associated with severe coronavirus disease‐19 (COVID‐19) has brought a shift in the way we envision aberrant endosomal acidification. Is it linked to an increased susceptibility to viral infection or a propensity to develop critical illness? This review summarizes the genetic and cellular evidence linking endosomal Na+/H+ exchangers and viral diseases to suggest how they can act as a broad‐spectrum modulator of viral infection and downstream pathophysiology. The review also presents novel insights supporting the complex role of endosomal acid‐base homeostasis in viral pathogenesis and discusses the potential causes for negative outcomes of clinical trials utilizing alkalinizing drugs as therapies for COVID‐19. These findings lead to a pathogenic model of viral disease that predicts that nonspecific targeting of endosomal pH might fail, even if administered early on, and suggests that endosomal Na+/H+ exchangers may regulate key host antiviral defence mechanisms and mediators that act to drive inflammatory organ injury.
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Affiliation(s)
- Hari Prasad
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bengaluru, India
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