SMAD5 Monoclonal Antibody

Definition and Biological Context

SMAD5 is a receptor-regulated SMAD (R-SMAD) protein activated by BMP type 1 receptors. It forms complexes with SMAD4 to regulate gene expression, influencing processes such as hematopoiesis, osteogenesis, and cancer progression . Monoclonal antibodies targeting SMAD5 enable precise detection in experimental workflows like Western blot (WB), immunohistochemistry (IHC), and immunofluorescence (IF) .

Key Monoclonal Antibodies and Their Properties

The table below summarizes commercially available SMAD5 monoclonal antibodies and their specifications:

Oncogenic Regulation and miR-155 Interaction

• SMAD5 is a direct target of microRNA-155 (miR-155) in diffuse large B-cell lymphoma (DLBCL). Overexpression of miR-155 reduces SMAD5 levels, leading to resistance against BMP- and TGF-β1-induced cytostatic effects. This disruption impairs p21 expression, accelerating tumor growth .

• Stable SMAD5 knockdown in DLBCL cell lines recapitulates miR-155’s oncogenic effects, confirming SMAD5’s tumor-suppressive role .

BMP/TGF-β Signaling Crosstalk

• SMAD5 mediates BMP-induced transcriptional activation of ID1, ID2, and BMP6 but is also activated by TGF-β1 in DLBCL. This dual signaling role highlights its importance in balancing cell proliferation and differentiation .

Western Blot Performance

• MA5-15793 detects SMAD5 in human and rat lysates at ~52 kDa, aligning with its predicted molecular weight .

• Antibody 67052-1-Ig shows consistent reactivity in HEK-293, MCF-7, and NIH/3T3 cells .

Immunohistochemical Applications

• Clone AFB-19 (MAB20575) demonstrates strong staining in formalin-fixed paraffin-embedded human pancreas and cancer tissues .

Clinical and Mechanistic Implications

SMAD5 monoclonal antibodies have revealed its involvement in:

• Cancer Pathogenesis: Loss of SMAD5 correlates with defective cell cycle regulation and enhanced tumor aggressiveness in DLBCL .

• Metabolic Regulation: Non-phosphorylated SMAD5 promotes glycolysis by interacting with hexokinase 1, linking metabolic reprogramming to BMP signaling .

Limitations and Considerations

• Cross-reactivity with SMAD1/8/9 is observed in some antibodies (e.g., ab92698), necessitating validation in target-specific assays .

• Optimal dilution ratios vary by application and cell type, requiring empirical testing .