Tbx15 Knockout ST2 Cell Line

The Tbx15 Knockout ST2 Cell Line is a CRISPR/Cas9-engineered ST2 cell line featuring targeted disruption of the Tbx15 gene, enabling loss-of-function studies in a well-characterized bone marrow stromal background. This stable, proliferative model provides a renewable source of Tbx15-null cells that retain the parental line’s differentiation potential for detailed mechanistic analyses.

The ST2 parental line originates from the bone marrow of BC8 mice (BALB/c substrain) and displays properties of mesenchymal stromal cells. It supports hematopoietic progenitor co-culture and, under defined conditions, undergoes osteoblast differentiation with mineralization or adipogenic conversion with lipid droplet formation. The BALB/c genetic background ensures reproducibility for investigating skeletal biology, adipogenesis, and metabolic regulatory networks.

Tbx15 encodes a T-box transcription factor that orchestrates mesodermal lineage allocation. It functions downstream of BMP2/BMPR1A/SMAD1/5/8 and Wnt3a/Frizzled/??-catenin cascades, integrating pro-osteogenic signals. Tbx15 physically interacts with TLE/Groucho corepressors and SMAD1/5/8 to directly upregulate Runx2 and Osterix (Sp7), the master drivers of osteoblast commitment, while simultaneously repressing the adipogenic regulator PPAR??. This dual activity promotes bone formation and suppresses fat cell development. Tbx15 also modulates UCP1 expression in brown/beige adipocytes, influencing thermogenic capacity.

In the ST2 context, Tbx15 knockout is predicted to skew differentiation toward adipogenesis at the expense of osteogenesis, recapitulating features of marrow fat infiltration and bone loss associated with aging and metabolic disease. This cell line therefore provides a genetically defined tool to dissect the BMP/Wnt?CTbx15?CRunx2/Osterix regulatory axis and its roles in conditions such as Cousin syndrome, obesity-related skeletal fragility, and type 2 diabetes-induced bone changes.

Typical research applications include alkaline phosphatase activity assays and alizarin red staining to assess mineralization capacity, Oil Red O staining for adipocyte formation, RT-qPCR profiling of Tbx15, Runx2, and Osterix expression, and western blot detection of Runx2, PPAR??, and UCP1. Luciferase reporter assays enable direct examination of Runx2 or Osterix promoter activity. The model is also suitable for co-culture with hematopoietic cells to evaluate stromal support function and for pharmacological rescue experiments using BMP2 or Wnt3a to probe signaling redundancy. For further information, please contact Ascent Research.