WT1 regulates HOXB9 gene expression in a bidirectional way

Area of Science:

• Molecular Biology
• Developmental Biology
• Cancer Biology

Background:

• The homeoboxB9 (HOXB9) gene is crucial for embryonic anterior-posterior axis specification and is implicated in various cancers.
• The Wilms tumor transcription factor WT1 plays a significant role in kidney development and oncogenesis.

Purpose of the Study:

• To investigate the regulatory relationship between WT1 and HOXB9.
• To elucidate the mechanisms by which WT1 influences HOXB9 expression.
• To determine the potential relevance of this interaction in kidney development and cancer.

Main Methods:

• Gene silencing and overexpression studies in various cell lines (786-0, M15, U2OS, HEK293).
• CRISPR/Cas9-mediated gene deletion.
• Reporter gene assays to assess promoter activity.
• Electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP) to confirm protein-DNA binding.
• Co-transfection experiments with BASP1.

Main Results:

• WT1 exhibits bidirectional regulation of HOXB9.
• HOXB9 is activated upon WT1 silencing in WT1-expressing cells.
• HOXB9 is upregulated by WT1 overexpression in WT1-null cells.
• WT1 directly binds to the HOXB9 promoter.
• The co-repressor BASP1 is involved in WT1-mediated repression of HOXB9.
• HOXB9 and WT1 show non-overlapping expression patterns in embryonic kidneys.

Conclusions:

• HOXB9 is identified as a novel downstream target of WT1.
• WT1's effect on HOXB9 expression is context-dependent, either stimulating or repressing transcription.
• BASP1 mediates the inhibitory function of WT1 on HOXB9.
• The WT1-HOXB9 regulatory axis may be significant in kidney development and cancer progression.