Selective gene silencing in activated leukocytes by targeting siRNAs to the integrin lymphocyte function-associated antigen-1

• DOI: 10.1073/pnas.0608491104
• Publication Date: 2007-03-01T11:29:21Z
• Authors: Dan Peer; Pengcheng Zhu; Christopher V. Ca...; Judy Lieberman; Motomu Shimaoka
• Keywords: 0301 basic medicine; 570; Dose-Response Relationship, Drug; Receptors, CCR5; Recombinant Fusion Proteins; T-Lymphocytes; 610; Antigens, Nuclear; Mice, SCID; Lymphocyte Function-Associated Antigen-1; 3. Good health; DNA-Binding Proteins; Mice; 03 medical and health sciences; Cell Adhesion; Animals; Humans; Gene Silencing; RNA, Small Interfering; K562 Cells; Ku Autoantigen; Cell Proliferation

Silencing gene expression by RNAi is a powerful method for exploring gene function and validating drug targets and potentially for therapy. Lymphocytes and other primary blood cells are resistant to lipid-based transfectionin vitroand are difficult to targetin vivo. We show here that antibody-protamine fusion proteins targeting the human integrin lymphocyte function-associated antigen-1 (LFA-1) efficiently deliver siRNAs and specifically induce silencing in primary lymphocytes, monocytes, and dendritic cells. Moreover, a fusion protein constructed from an antibody that preferentially recognizes activation-dependent conformational changes in LFA-1 selectively targets activated leukocytes and can be used to suppress gene expression and cell proliferation only in activated lymphocytes. The siRNA-fusion protein complexes do not cause lymphocyte activation or induce IFN responses. K562 cells expressing latent WT or constitutively activated LFA-1 engrafted in the lungs of SCID mice are selectively targeted by intravenously injected fusion protein–siRNA complexes, demonstrating the potentialin vivoapplicability of LFA-1-directed siRNA delivery.