Name: INI-1 (BAF47/SNF5) Antibody (Clone 25/BAF47)
Description and applications: SWI/SNF complexes facilitate gene activation and transcription factor binding by altering repressive chromatin structures in an ATP-dependent manner. In mammals, SWI/SNF complexes are present in mutliple forms that include 9-12 BRG1-associated factors (BAFs) per complex. These BAF proteins range in molecular weight from 47 to 250 kDa. BAF47/SNF5 (SMARCB1/Ini1) complexes with BRG1- and BRM-containing SWI/SNF complexes. BAF47/SNF5 mRNA is widely expressed in cell lines and tissues, and BAF47/SNF5 gene is mutated in many human tumors. The latter is indicative of a tumor suppressor role for BAF47/SNF5. In addition, mice deficient for BAF47 die early in embryogenesis, while BAF47/SNF5 heterozygous mice display a variety of tumors in the soft tissues of the head and neck. BAF47/SNF5 also binds the HIV-1 integrase and stimulates integrase-mediated DNA joining activity. Thus, BAF47/SNF5 is a component of SWI/SNF complexes that may be critical for normal development and tumor suppression, but may also be a protein utilized for viral DNA integration into host DNA. Expression in normal tissues is ubiquitous. In tumor tissue loss of protein expression SMARCB1 / INI1 gene was first observed in all malignant rhabdoid tumors of childhood of different location (soft tissue, kidney and CNS) and in medullary carcinomas of the kidney. Also loss of expression is observed in 50% of synovial sarcomas, some myxoid chondrosarcoma and myoepithelial carcinomas, almost all epithelioid sarcoma (proximal and conventional variants) and 50% of malignant tumors of peripheral nerves sheat, all presenting rhabdoid morphology. Loss of immunohistochemistry expression is also observed in cases of poorly differentiated chordoma. The antibody is useful in differentiating rhabdoid tumors of other tumors with similar morphology as desmoplastic round cell tumor, rhabdomyosarcoma and Wilms tumor do not show loss of expression of INI1. The antibody also is useful in confirming the diagnosis of medullary carcinoma and discard possible renal pelvis urothelial carcinoma or other carcinomas of the kidney showing expression for INI1. Maintained staining in most carcinomas, epithelioid angiosarcoma, mesotheliomas, melanomas and other tumors or lesions reagents (granulomas) of epithelioid morphology make this useful antibody in the diagnosis of epithelioid sarcoma.
Composition: anti-human INI-1 mouse monoclonal antibody purified from serum and prepared in 10mM PBS, pH 7.4, with 0.2% BSA and 0.09% sodium azide.
Immunogen: mouse BAF47 aminoacids 257-359.