Neural progenitor cells have the ability to give rise to neurons and glia in the embryonic, postnatal and adult brain. During development, the program regulating whether these cells divide and self-renew or exit the cell cycle and differentiate is tightly controlled, and imbalances to the normal trajectory of this process can lead to severe functional consequences. However, our understanding of the molecular regulation of these fundamental events remains limited. Moreover, processes underpinning development of the postnatal neurogenic niches within the cortex remain poorly defined. Here, we demonstrate that Nuclear factor one X (NFIX) is expressed by neural progenitor cells within the embryonic hippocampus, and that progenitor cell differentiation is delayed within Nfix(-/-) mice. Moreover, we reveal that the morphology of the dentate gyrus in postnatal Nfix(-/-) mice is abnormal, with fewer subgranular zone neural progenitor cells being generated in the absence of this transcription factor. Mechanistically, we demonstrate that the progenitor cell maintenance factor Sry-related HMG box 9 (SOX9) is upregulated in the hippocampus of Nfix(-/-) mice and demonstrate that NFIX can repress Sox9 promoter-driven transcription. Collectively, our findings demonstrate that NFIX plays a central role in hippocampal morphogenesis, regulating the formation of neuronal and glial populations within this structure.

Objective. To investigate the role of proteinaseactivated receptor 4 (PAR-4) in mediating joint inflammation and pain in mice.Methods. Knee joint blood flow, edema, and pain sensitivity (as induced by thermal and mechanical stimuli) were assessed in C57BL/6 mice following intraarticular injection of either the selective PAR-4 agonist AYPGKF-NH 2 or the inactive control peptide YAPGKF-NH 2 . The mechanism of action of AYPGKF-NH 2 was examined by pretreatment of each mouse with either the PAR-4 antagonist pepducin P4pal-10 or the bradykinin antagonist HOE 140. Finally, the role of PAR-4 in mediating joint inflammation was tested by pretreating mice with acutely inflamed knees with pepducin P4pal-10.Results. PAR-4 activation caused a long-lasting increase in joint blood flow and edema formation, which was not seen following injection of the control peptide. The PAR-4-activating peptide was also found to be pronociceptive in the joint, where it enhanced sensitivity to a noxious thermal stimulus and caused mechanical allodynia and hyperalgesia. The proinflammatory and pronociceptive effects of AYPGKF-NH 2 could be inhibited by pepducin P4pal-10 and HOE 140. Finally, pepducin P4pal-10 ameliorated the clinical and physiologic signs of acute joint inflammation.Conclusion. This study demonstrates that local activation of PAR-4 leads to proinflammatory changes in the knee joint that are dependent on the kallikreinkinin system. We also show for the first time that PARs are involved in the modulation of joint pain, with PAR-4 being pronociceptive in this tissue. Thus, blockade of articular PAR-4 may be a useful means of controlling joint inflammation and pain.

Key Points• Restricting transgenic antigen expression to differentiated antigen-presenting cells protects hematopoietic progenitors from immune attack.• Restricting transgenic antigen expression to differentiated antigen-presenting cells promotes tolerogenic outcomes.

CD4 1 T cells are important effectors of inflammation and tissue destruction in many diseases of immune dysregulation. As memory T cells develop early during the preclinical stages of autoimmune and inflammatory diseases, immunotherapeutic approaches to treatment of these diseases, once established, must include the means to terminate memory T-cell responses. Traditionally, it has been considered that, due to their terminally differentiated nature, memory T cells are resistant to tolerance induction, although emerging evidence indicates that some immunotherapeutic approaches can terminate memory T-cell responses. Here, we demonstrate that CD4 1 memory T-cell responses can be terminated when cognate antigen is transgenically expressed in steady-state DC. Transfer of in-vitrogenerated CD4 1 memory T cells establishes, in nontransgenic recipients, a stable and readily recalled memory response to cognate antigen. In contrast, upon transfer to mice expressing cognate antigen targeted to DC, memory CD4 1 T cells undergo a phase of limited proliferation followed by substantial deletion, and recall responses are effectively silenced. This finding is important in understanding how to effectively apply immunotherapy to ongoing T-cell-mediated autoimmune and inflammatory diseases.Key words: CD4 1 T cells . DC . Tolerance See accompanying Commentary by Kurts IntroductionNegative selection and peripheral tolerance mechanisms jointly serve to limit the development of autoaggressive self-reactive T-cell responses. However, in autoimmune-prone individuals these control mechanisms can fail and autoimmune disease ensues. As autoimmune diseases progress, intra-and intermolecular determinant spreading occurs [1] and populations of effector and memory T cells become established. Therefore, unlike strategies directed at preventing the development of autoimmune disease, where induction of tolerance in naïve T cells may be all that is required, therapies aimed at terminating ongoing autoimmune disease must be capable of inactivating established populations of memory or activated effector T cells.Although naïve T cells are highly dependent on the presence or absence of costimulatory signals to determine the outcome of activation, costimulation appears to play little role in controlling the responses of memory and effector T cells [2,3] and these cells are considered costimulation independent. Because of this, in contrast to naïve T cells which are readily deleted or inactivated in the absence of costimulation memory T cells are widely regarded as potentially resistant to tolerance induction. If this were indeed the case, then effector and memory T cells represent a significant hurdle to therapeutic strategies aimed at treating autoimmune diseases. However, we have recently shown that memory and effector CD8 1 T cells are susceptible to tolerance induction when cognate antigen is expressed in DC and other APC types [4]. 2016The relative roles of CD4 1 and CD8 1 T cells in disease progression differ depending on the autoimmune disease bu...

Within the adult mammalian brain, neurogenesis persists within two main discrete locations, the subventricular zone lining the lateral ventricles, and the hippocampal dentate gyrus. Neurogenesis within the adult dentate gyrus contributes to learning and memory, and deficiencies in neurogenesis have been linked to cognitive decline. Neural stem cells within the adult dentate gyrus reside within the subgranular zone (SGZ), and proteins intrinsic to stem cells, and factors within the niche microenvironment, are critical determinants for development and maintenance of this structure. Our understanding of the repertoire of these factors, however, remains limited. The deubiquitylating enzyme USP9X has recently emerged as a mediator of neural stem cell identity. Furthermore, mice lacking Usp9x exhibit a striking reduction in the overall size of the adult dentate gyrus. Here we reveal that the development of the postnatal SGZ is abnormal in mice lacking Usp9x. Usp9x conditional knockout mice exhibit a smaller hippocampus and shortened dentate gyrus blades from as early as P7. Moreover, the analysis of cellular populations within the dentate gyrus revealed reduced stem cell, neuroblast and neuronal numbers and abnormal neuroblast morphology. Collectively, these findings highlight the critical role played by USP9X in the normal morphological development of the postnatal dentate gyrus.