title: JAK protein kinase inhibitors.
abstract: In humans, the Janus protein tyrosine kinase family (JAKs) contains four members: JAK1, JAK2, JAK3 and TYK2. JAKs phosphorylate signal transducers and activators of transcription (STATs) simultaneously with other phosphorylations required for activation, and there are several cellular mechanisms in place to inhibit JAK/STAT signaling. That one might be able to modulate selected JAK/STAT-mediated cellular signals by inhibiting JAK kinase activity to effect a positive therapeutic outcome is a tantalizing prospect, as yet incompletely realized. While current data suggest no therapeutic use for JAK1 and TYK2 inhibition, JAK2 inhibition seems a promising but not definitively tested mechanism for treatment of leukemia. More promising, however, are data indicating a possible therapeutic use of JAK3 inhibition. The restriction of the JAK3-deficient phenotype to the hematopoietic system and the resulting profound immune suppression suggest that JAK3 could be a target for immunosuppressive therapies used to prevent organ transplant rejection.
authors.affiliation: Department of Immunology and Rheumatology, Merck Research Laboratories, Rahway, New Jersey 07065, USA. Jed_thompson@merck.com
authors.forename: James E
authors.initials: JE
authors.lastname: Thompson
mesh_terms: D000818:Animals; D015195:Drug Design; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005544:Forecasting; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D053613:Janus Kinase 1; D053614:Janus Kinase 2; D053616:Janus Kinase 3; D008352:Mannich Bases / Q000494:pharmacology; D010880:Piperidines; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D011743:Pyrimidines / Q000494:pharmacology; D011758:Pyrroles / Q000494:pharmacology; D011799:Quinazolines / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D053634:TYK2 Kinase
chemical_list: D004791:Enzyme Inhibitors; D008352:Mannich Bases; C503557:NC 1153; D010880:Piperidines; D011518:Proto-Oncogene Proteins; D011743:Pyrimidines; D011758:Pyrroles; D011799:Quinazolines; C116180:WHI P131; C479163:tofacitinib; D011505:Protein-Tyrosine Kinases; C507904:JAK1 protein, human; C507924:JAK2 protein, human; C507933:JAK3 protein, human; D053613:Janus Kinase 1; D053614:Janus Kinase 2; D053616:Janus Kinase 3; D053634:TYK2 Kinase; C070139:TYK2 protein, human