Novel peptide-based inhibitor for targeted inhibition of T cell function.

Novel immunosuppressants are sought to overcome the side effects of currently used drugs. T cells play a central role in the functioning of the immune system; hence, drugs that specifically inhibit T cell function are expected to be better immunosuppressants with fewer side effects than the ones currently used. Peptides that interfere with crucial protein-protein interactions (PPIs) have been shown to influence cell physiology and have therapeutic potential. In this study, we designed a peptide, GVITAA, which specifically inhibits the function of lymphocyte-specific protein kinase (LCK), a signaling molecule that is mainly expressed in T cells and is responsible for positively regulating T cell function. Aspartate Histidine -Histidine Cysteine (DHHC21) -LCK is an important PPI present in T cells; DHHC21 interacts with LCK and targets the kinase to membrane rafts by adding a palmitoyl group. GVITAA is a ten amino acid peptide that interferes with the DHHC21-LCK interaction, prevents the membrane localization of LCK, and inhibits LCK-mediated initiation of complex signal transduction pathways required for T cell activation. In this study, we present evidence that the GVITAA peptide when conjugated with a cell-penetrating peptide-human immunodeficiency virus transactivator of transcription (TAT) and incubated with mouse T cells specifically inhibits LCK-mediated T cell receptor signaling, cytokine secretion, and T cell proliferation. This peptide does not affect other non-T cell functions and is non-toxic. A similar strategy was also tested and demonstrated in human peripheral T cells.

Differential expression of NF-κB heterodimer RelA/p50 in human urothelial carcinoma.

BACKGROUND: Urothelial carcinoma (UC) is the fifth most common malignancy that accounts for 5% of all cancers. Diagnostic markers that predict UC progressions are inadequate. NF-κB contributes towards disease progression upon constitutive activation in many solid tumors. The nuclear localization of NF-κB indicates increased transcriptional activity while cytoplasmic localization indicates the inactive protein repository that can be utilized readily by a malignant cell. This study delineates the nuclear and cytoplasmic differential expression of NF-κB heterodimers in UC progression. METHODS: The involvement of the NF-κB proteins in UC was analyzed in silico using cytoscape. The expression of NF-κB heterodimers was analyzed by immunohistochemistry. RESULTS: PINA4MS app in cytoscape revealed over expression of RelA and suppression of NF-κB1 (p50 precursor) in UC whereas the expression of NF-κB target proteins remained unhindered. Immunohistochemical localization showed nuclear RelA/p50 in low grade UC whereas in high grade only RelA expression was observed. Conversely, cytoplasmic expression of RelA/p50 remained extensive across high and low grade UC tissues (p < 0.005). RelA nuclear and cytoplasmic expression (p < 0.005) was directly proportional to the disease progression. In our study, some of the high-grade UC tissues with squamous differentiation and muscle invasion had extensive nuclear p50 localization. The phenomenon of RelA/p50 expression seen increased in low-grade UC than high grade UC might be due to their interaction with other members of NF-κB family of proteins. Thus, NF-κB RelA/p50 differential expression may play a unique role in UC pathogenesis and can serve as a biomarker for diagnosis.