Abstract: TH-PO0264
NHA2, a Sodium-Hydrogen (Na+/H+) Exchanger Linked to Hypertension and Diabetes, Is Essential for Golgi Homeostasis
Session Information
- Hypertension and CVD: Mechanisms
November 06, 2025 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Hypertension and CVD
- 1601 Hypertension and CVD: Basic
Authors
- Albano, Giuseppe, Universitat Bern, Bern, BE, Switzerland
- Ho, Tin Manh, Universitat Bern, Bern, BE, Switzerland
- Fuster, Daniel G., Bern University Hospital, Bern, BE, Switzerland
Group or Team Name
- Experimental Nephrology.
Background
NHA2, encoded by the SLC9B2 gene, is an orphan Na+/H+ exchanger (NHE) implicated in human hypertension and diabetes mellitus. Despite its clinical relevance, the molecular function of NHA2 remains poorly understood. Through an unbiased proteomic screen, we identified the cis-Golgi membrane protein GPP130 as a putative interacting partner of NHA2. We investigated the role of NHA2 in regulating GPP130 stability, Golgi structure, and cis-Golgi pH homeostasis.
Methods
Co-localization studies were performed to assess the subcellular distribution of NHA2 and GPP130. Western blotting and proteomic analysis were utilized to quantify GPP130 protein levels in NHA2-deficient cells. Golgi integrity was assessed through immunofluorescence microscopy, and pH-sensitive probes were employed to measure cis-Golgi acidification. Oligomerization of GPP130 was analyzed via crosslinking assays, and truncation mutagenesis was employed to identify key domains involved in GPP130 oligomerization.
Results
NHA2-deficient cells exhibited a substantial reduction in GPP130 protein levels, driven by enhanced lysosomal degradation. Both NHA2 and GPP130 localized to the cis-Golgi, and loss of NHA2 led to pronounced Golgi fragmentation. NHA2-deficient cells displayed abnormal acidification of the cis-Golgi, a phenotype reversed by the expression of wild-type NHA2, but not by a catalytically inactive mutant. Additionally, loss of NHA2 induced pH-dependent oligomerization of GPP130, targeting it for lysosomal degradation. Truncation analysis revealed that the luminal region spanning amino acids 36–87 of GPP130 is critical for its pH-dependent oligomerization.
Conclusion
Our findings establish NHA2 as a key regulator of cis-Golgi pH, GPP130 stability, and overall Golgi integrity. By controlling pH within the cis-Golgi compartment, NHA2 prevents the aberrant oligomerization and degradation of GPP130, thereby maintaining Golgi structure and function. These results elucidate a novel molecular mechanism linking NHA2 to Golgi homeostasis and provide insights into its potential role in hypertension and diabetes pathogenesis.