Abstract: SA-PO0274
Sulfate Transporter SLC26A1 Is Crucial for Musculoskeletal Health
Session Information
- Bone and Mineral Metabolism: Basic Research
November 08, 2025 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Bone and Mineral Metabolism
- 501 Bone and Mineral Metabolism: Basic
Authors
- Pitzken, Felix, Charite - Universitatsmedizin Berlin, Berlin, BE, Germany
- Fretz, Jackie A., Yale School of Medicine, New Haven, Connecticut, United States
- Jiang, Zhirong, Yale School of Medicine, New Haven, Connecticut, United States
- Zimmermann, Amelie Audrey, Charite - Universitatsmedizin Berlin, Berlin, BE, Germany
- Westendorf, Jennifer J, Mayo Clinic Minnesota, Rochester, Minnesota, United States
- Aronson, Peter S., Yale School of Medicine, New Haven, Connecticut, United States
- Knauf, Felix, Mayo Clinic Minnesota, Rochester, Minnesota, United States
Group or Team Name
- Knauf Lab.
Background
Sulfate contributes to glycosaminoglycan structure and signaling. SLC26A1 mediates renal sulfate reabsorption in the proximal tubule. Mutations in humans are associated with severe hyposulfatemia due to renal sulfate wasting, reduced spine length, increased fracture risk, and decreased bone mineralization. We generated a mouse deficient for Slc26a1 to mimic the observations in humans.
Methods
To delete Slc26a1, we used CRISPR/Cas9 and confirmed deletion with PCR and immunoblotting. Plasma and urine sulfate levels were measured by turbidimetry. Bone structure, density, and distal-femur and L5 vertebral body mineralization were assessed with micro-computed tomography (µCT) and calcein-based bone histomorphometry. Safranin O staining and dimethylmethylene blue (DMMB) were used to analyze skeletal proteoglycan (PG) sulfation.
Results
Slc26a1-null exhibited marked reduction in plasma sulfate associated with greatly increased fractional excretion of sulfate, confirming renal sulfate wasting. Bone histomorphometry showed impaired turnover, with double-labeled surfaces reduced by 51% in males and 44% in females (p < 0.01). Mineral apposition rate declined by 26% in females (p < 0.01) and 15% in males (n.s.), while bone formation rate was reduced by 38% in males (p < 0.001) and 33% in females (p < 0.01). Osteoblasts decreased 25% in males, (p < 0.01), with unchanged osteoclasts, female data pending. Safranin O staining confirmed reduced PG sulfation in KO mice. Saturation decreased 21% in males (p = 0.038) and 31% in females (p = 0.055, n.s.) in the growth plate, and 48% in males (p = 0.042) and 31% in females (p = 0.031) in bone, indicating defective sulfate incorporation. The DMMB assay showed a 36% reduction in cartilage PG sulfation (p < 0.05). µCT analysis revealed disturbed L5 trabecular architecture in males only, with vertebral connectivity density reduced by 24% (p < 0.01), and trabecular number by 7% (p < 0.01). Similarly, in the femur, bone volume was reduced by 13% (p < 0.05), connectivity density by 23% (p < 0.01), and apparent trabecular density by 17% (p < 0.01).
Conclusion
The Slc26a1-null mouse model links renal sulfate homeostasis to skeletal integrity. Our findings demonstrate the impact of the defective transporter on proteoglycan composition, cartilage structure, and bone mineralization.
Funding
- NIDDK Support