The PTK-STAT signaling pathway has essential roles in T-cell activation in response to antigen stimulation

Interferon regulatory factor 8 integrates T-cell receptor and cytokine-signaling pathways and drives effector differentiation of CD8 T cells

We recently demonstrated that differentiation of cytotoxic T cells requires cooperation between T-cell receptor (TCR)/costimulation and γc-cytokines. Here we demonstrate that the transcription factor IFN regulatory factor 8 (IRF8) is expressed in CD8 T cells by the combination of these two signals. More importantly, depletion of IRF8 in these cells abrogated the differentiation of naive CD8 T cells into effector cells in an experimental graft-vs.-host disease mouse model. We also show that IRF8 seems to not operate upstream of other critical factors such as T-bet and eomesodermin, which have been implicated in effector maturation. Collectively, our work shows that IRF8 integrates the TCR/costimulation and γc-cytokine-signaling pathways and mediates the transition of naive CD8 T cells to effector cells, thus identifying IRF8 as one of the molecular regulators of CD8 T-cell differentiation.

Molecular cloning and characterization of the STAT gene in Hyphantria cunea haemocytes

A new insect member of the signal transducer and activator of transcription (STAT) family of transcription factors, Hyphantria cunea STAT (HcSTAT), was cloned from the lepidopteran H. cunea. The domain involved in DNA interaction and the Src homology 2 (SH2) domain were well conserved. During all developmental stages, the gene was expressed at a low level in the haemocytes, fat body cells, midgut, epidermis and Malpighian tubules. The haemocytes and Malpighian tubules showed transcriptional activation of HcSTAT upon Gram-negative and Gram-positive bacterial challenges. These challenges increased the induction and nuclear translocation of the HcSTAT protein that recognizes a STAT target site in H. cunea haemocytes. In vivo treatment with sodium orthovanadate translocated HcSTAT to the haemocyte nucleus. This study shows the involvement of the haemocyte Janus kinase/STAT pathway after microbial infection in lepidopteran insects.

A new hypothalamic polypeptide is a regulator of myelopoiesis

The effect of hypothalamic proline-rich polypeptide (PRP) against Pseudomonas aeruginosa infection in BALB/c mice with leukopenia was investigated. Mice were treated with cyclophosphamide (CPA) and were then injected with PRP 24 h after CPA treatment. The lethal doses of P. aeruginosa were injected to mice when the number of peripheral blood leukocytes reached a nadir on day 5 after CPA administration. The administration of PRP significantly increased the survival of infected mice, and had a pronounced protective effect during the period of development of the infection. The number of bacteria in internal organs of PRP-treated mice was significantly lower than that in control mice. In PRP-treated mice, the neutrophil levels in peripheral blood started to increase 7 days after CPA administration and were consistently higher, and they were more mature than those in controls. Our results may indicate the ability of PRP to stimulate recovery of myelopoiesis and enhance mature neutrophil function.