title: The adaptor protein NTAL enhances proximal signaling and potentiates corticosteroid-induced apoptosis in T-ALL.
abstract: The biology of T-cell acute lymphoblastic leukemia (ALL) is characterized by functional pre-T-cell receptor (TCR) signaling. Non-T-cell activation linker (NTAL) is a nonenzymatic transmembrane adaptor molecule that is involved in the proximal signaling of lymphocytes. In our previous work, we found an association between high NTAL expression in T-cell ALL blasts and a favorable response to initial glucocorticoid treatment. In the present study, we confirm our previous observation in an experimental model. In addition, the molecular mechanism of the contribution of NTAL to malignant T-cell ALL blast signaling and to methylprednisolone-induced cell death is analyzed. In the in vitro experiments, we used the T-cell ALL Jurkat cell line (Jurkat/wt) and derived Jurkat cell line with stable NTAL expression (Jurkat/NTAL(+)). Cell signaling and cell death after methylprednisolone treatment and after TCR stimulation were analyzed using flow cytometry, Western blot, and quantitative polymerase chain reaction. Jurkat/NTAL(+) cells are significantly more sensitive to both methylprednisolone treatment and TCR-induced stimulation. In addition, after TCR stimulation, Jurkat/NTAL(+) cells show a higher level of intracellular extracellular signal-regulated kinase 1/2 (ERK) phosphorylation and increased expression of the CD69 activation marker on the cell surface than the Jurkat/wt cells. The ERK inhibitor U0126 almost completely abrogates TCR-induced cell death and, importantly, reverses the sensitizing effect of the NTAL protein on methylprednisolone-induced cell death. In conclusion, NTAL acts as a tumor suppressor that enhances the proximal signaling of leukemic blasts. The key downstream molecule responsible for the biological effect of TCR signaling is ERK. Higher ERK phosphorylation leads to enhanced cell death after TCR stimulation and increases cell sensitivity to methylprednisolone-induced cell death.
authors.affiliation: CLIP-Childhood Leukemia Investigation Prague, Prague, Czech Republic. karel.svojgr@lfmotol.cuni.cz
authors.forename: Karel
authors.initials: K
authors.lastname: Svojgr
authors.forename: Tomas
authors.initials: T
authors.lastname: Kalina
authors.forename: Veronika
authors.initials: V
authors.lastname: Kanderova
authors.forename: Tereza
authors.initials: T
authors.lastname: Skopcova
authors.forename: Tomas
authors.initials: T
authors.lastname: Brdicka
authors.forename: Jan
authors.initials: J
authors.lastname: Zuna
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000502:physiology*; D015703:Antigens, CD / Q000378:metabolism; D000945:Antigens, Differentiation, T-Lymphocyte / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D002070:Butadienes / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D019169:Jurkat Cells / Q000187:drug effects / Q000201:enzymology; D037181:Lectins, C-Type / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008775:Methylprednisolone / Q000494:pharmacology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*; D009570:Nitriles / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D054218:Precursor T-Cell Lymphoblastic Leukemia-Lymphoma / Q000378:metabolism* / Q000473:pathology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D011948:Receptors, Antigen, T-Cell / Q000187:drug effects; D000099192:CD69 Antigens
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D002070:Butadienes; D037181:Lectins, C-Type; D008775:Methylprednisolone; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D009363:Neoplasm Proteins; D009570:Nitriles; D047428:Protein Kinase Inhibitors; D011948:Receptors, Antigen, T-Cell; D000099192:CD69 Antigens; C419196:LAT2 protein, human; C113580:U 0126; C535150:MAPK1 protein, human