JAK2 V617F Mutation in Adult T Cell Leukemia-Lymphoma.

Adult T cell Leukemia/lymphoma (ATL) is a mature T-cell neoplasm that has strong association with the human T-lymphotropic virus type 1 (HTLV-I) infection. This infection is endemic in our region (north eastern Iran). It has been highlighted that Janus Kinase family proteins and specially JAK2 mutations have a pivotal role in the development of many types of hematological malignancies and in particular myeloproliferative neoplasms. So far, the underlying molecular mechanisms leading to the ATL are not well understood. Therefore, in this study it was hypothesized that JAK2 (V617F) mutation may be present in samples from patients with ATL. This case control study was performed in north-eastern Iran. Using polymerase chain reaction, JAK2 (V617F) mutation was performed in 20 DNA samples from ATL patients and 20 HTLV-1 asymptomatic carriers (control group). The results of ATL subjects and the control group were compared by using SPSS software. In the case group 13 (65 %) and 7 patients (35 %) were male and female respectively, with the age range between 40 and 80 years. Only one patients has JAK2 mutation and this mutation was absent in 95 % of ATL patients as well as the HTLV-1 asymptomatic carriers. The results of our study demonstrated that JAK2 V617F mutation is not a common phenomenon in ATL. However, further studies are required to investigate the possible dysregulation of JAK signaling in ATL.

Role of Janus-Kinases in Major Depressive Disorder.

BACKGROUND/AIMS: Major depressive disorder is a severe, common and often chronic disease with a significant mortality due to suicide. The pathogenesis of major depression is still unknown. It is assumed that a reduction of neurogenesis in the hippocampus plays an important role in the development of major depressive disorder. However, the mechanisms that control proliferation of neuronal stem cells in the hippocampus require definition. Here, we investigated the role of Janus-Kinase 3 (Jak-3) for stress-induced inhibition of neurogenesis and the induction of major depression symptoms in mice. METHODS: Stress was induced by the application of glucocorticosterone. Brain sections were stained with phospho-specific antibodies and analysed by confocal microscopy to measure phosphorylation of Jak-3 specifically in the hippocampus. Jak-3 inhibitors and the antidepressant amitriptyline were applied to counteract stress. The effects of the inhibitors were determined by a set of behavioural tests and analysis of Jak-3 phosphorylation in brain sections. Acid sphingomyelinase-deficient mice were employed to test whether Jak3 is downstream of ceramide. RESULTS: The data show that stress reduces neurogenesis, which is restored by simultaneous application of Jak-3 inhibitors. Inhibition of neurogenesis correlated with an anxious-depressive behaviour that was also normalized upon application of a Jak-3-inhibitor. Confocal microscopy data revealed that stress triggers a phosphorylation and thereby activation of Jak-3 in the hippocampus. Amitriptyline, a commonly used antidepressant that blocks the acid sphingomyelinase, or acid sphingomyelinase-deficiency reduced stress-induced phosphorylation of Jak-3. CONCLUSION: Our data show that Jak-3 is activated by stress at least partially via the acid sphingomyelinase and is involved in the mediation of stress-induced major depression.