Intranuclear interactomic inhibition of FoxP3 suppresses functions of Treg cells.

Regulatory T cells (Treg cells) are crucial for the maintenance of immunological tolerance, and it has been reported that Treg cells are enriched within the tumor micro-environment for immune evasion due to their immunosuppressive functions. To inhibit Treg cells functions, FoxP3, a lineage-specific transcription factor responsible for the differentiation and functions of Treg cells, was functionally targeted by a nucleus-transducible (nt) form of various FoxP3 functional subdomains. These nt modified domains can be delivered into the nucleus effectively and work as interactomic inhibitors via disruption of the endogenous FoxP3-mediated transcription complex. Among these domains, nt-FoxP3-FKH (Forkhead DNA binding domain) is most effective at restoring NFAT activity suppressed by FoxP3, and inhibiting the binding of endogenous FKH-containing proteins to FKH DNA binding sequences without influencing the viability and activation of T cells. The suppressive functions of TGF-ß-induced iTreg cells and thymus-derived tTreg cells were substantially blocked by nt-FoxP3-FKH, accompanied with down-regulation of CTLA-4 surface expression and IL-10 secretion of Treg cells. In addition, nt-FoxP3-FKH upregulated the expression of IL-2 and IFN-γ in Treg cells. Therefore, nt-FoxP3-FKH has the potential to be a novel therapeutic agent to modulate the immune-evasive tumor environment created by Treg cells without the need for genetic modifications.

Amelioration of neurodegenerative diseases by cell death-induced cytoplasmic delivery of humanin.

Inhibition of the early intracellular event that triggers neurodegenerative cascades and reversal of neuronal cell death are essential for effective treatment of Alzheimer's disease (AD). In this study, a novel therapeutic for AD, a transducible humanin with an extended caspase-3 cleavage sequence (tHN-C3), was developed and showed multiple mechanisms of therapeutic action. These included targeted delivery of anti-apoptotic protein humanin through the blood-brain barrier (BBB) to neuronal cells, specific inhibition of caspase-3 activation to inhibit the early triggering of AD progression, and delivery of humanin into the cytoplasm of neuronal cells undergoing apoptosis where it exerts its anti-apoptotic functions effectively. The tHN-C3 prevented neuronal cell death induced by H2O2, or soluble Aß42, via Bax binding. In animal models of AD induced by amyloid beta, in Tg2576 mice, and in the rat middle cerebral artery occlusion model of stroke, tHN-C3 effectively prevented neuronal cell death, inflammatory cell infiltration into the brain, and improved cognitive memory. The therapeutic effectiveness of tHN-C3 was comparable to that of Aricept, a clinically approved drug for AD treatment. Therefore, tHN-C3 may be a new remedy with multiple therapeutic functions targeting the early and late stages of neurodegeneration in AD and other brain injuries.