RESUMEN
In the majority of myeloproliferative neoplasms (MPNs) patients, a point mutation, V617F has been found in Janus kinase 2 (JAK2) gene, and this JAK2 mutant provoked aberrant signaling pathway. In the current study, we found that suppressor of cytokine signaling proteins 3 (SOCS3) possessed the tumor suppressive activity against the JAK2 V617F mutant-provoked cellular transformation. The knockdown of SOCS3 increased the expression level of the JAK2 V617F mutant, which enhanced the activation of signaling mediators, including signal transducer and activator of transcription 3 and 5 (STAT3, STAT5) and extracellular signal-regulated kinase (ERK), and also increased of the proliferation rate and tumorigenesis activity of Ba/F3 cells expressing the JAK2 V617F mutant and erythropoietin receptor (EpoR). In contrast, the enforced expression of SOCS3 significantly inhibited the JAK2 V617F mutant-induced activation of downstream signaling molecules, cell proliferation, and tumorigenesis by down-regulating the expression level of the JAK2 V617F mutant. SOCS3 interacted with the JAK2V617F mutant through its SH2 domain and was phosphorylated at Tyr-204 and Tyr-221 in its SOCS box by the JAK2V617F mutant. SOCS3 mutants carrying a mutation in the SH2 domain (R71E) and a substitution at Tyr-221 (Y221F) failed to exert inhibitory effects on JAK2V617F mutant-induced cellular transformation and tumorigenesis. Collectively, these results imply that SOCS3 plays a negative role in the JAK2 V617F mutant-induced oncogenic signaling pathway through its SH2 domain and the phosphorylation of Tyr-221 in its SOCS box.
Asunto(s)
Transformación Celular Neoplásica/metabolismo , Neoplasias Hematológicas/metabolismo , Janus Quinasa 2/metabolismo , Mutación Missense , Trastornos Mieloproliferativos/metabolismo , Proteína 3 Supresora de la Señalización de Citocinas/metabolismo , Sustitución de Aminoácidos , Animales , Línea Celular , Transformación Celular Neoplásica/genética , Transformación Celular Neoplásica/patología , Neoplasias Hematológicas/genética , Neoplasias Hematológicas/patología , Janus Quinasa 2/genética , Ratones , Trastornos Mieloproliferativos/genética , Trastornos Mieloproliferativos/patología , Fosforilación/genética , Proteína 3 Supresora de la Señalización de Citocinas/genéticaRESUMEN
We investigated whether pre- and postnatal low-dose exposure to diesel exhaust (DE) affects male reproductive function in mice. The DE concentration is less than that indicated as the environmental quality standard for suspended particulate matter (SPM) in Japan. ICR mice were exposed prenatally to low-dose diesel exhaust (0.17 mg of DE particles/m³) through the airway for 8 h/day in an exposure chamber from gestational day 2 until the examination. In the DE-exposed groups, normal sperm morphology in the epididymis was reduced (p < 0.01), and seminiferous tubules showed degenerative changes in which the number of Sertoli cells was decreased (p < 0.01). Those changes were observed at 6 and 12 weeks of age. Furthermore, ultrastructural studies revealed an increase in damaged mitochondria in Sertoli cells (p < 0.001) and variform spermatozoa. These results indicate that pre- and postnatal exposure of low-dose DE is detrimental to Sertoli cell function and may cause abnormal spermatozoa.