A Disintegrin and Metalloprotease 10 in neuronal maturation and gliogenesis during cortex development

Regulation of Alpha-Secretase ADAM10 In vitro and In vivo: Genetic, Epigenetic, and Protein-Based Mechanisms

ADAM10 (A Disintegrin and Metalloproteinase 10) has been identified as the major physiological alpha-secretase in neurons, responsible for cleaving APP in a non-amyloidogenic manner. This cleavage results in the production of a neuroprotective APP-derived fragment, APPs-alpha, and an attenuated production of neurotoxic A-beta peptides. An increase in ADAM10 activity shifts the balance of APP processing toward APPs-alpha and protects the brain from amyloid deposition and disease. Thus, increasing ADAM10 activity has been proposed an attractive target for the treatment of neurodegenerative diseases and it appears to be timely to investigate the physiological mechanisms regulating ADAM10 expression. Therefore, in this article, we will (1) review reports on the physiological regulation of ADAM10 at the transcriptional level, by epigenetic factors, miRNAs and/or protein interactions, (2) describe conditions, which change ADAM10 expression in vitro and in vivo, (3) report how neuronal ADAM10 expression may be regulated in humans, and (4) discuss how this knowledge on the physiological and pathophysiological regulation of ADAM10 may help to preserve or restore brain function.

MAZ mediates the cross-talk between CT-1 and NOTCH1 signaling during gliogenesis

Neurons and glia cells are differentiated from neural stem/progenitor cells (NSCs/NPCs) during brain development. Concomitant activation of JAK/STAT and NOTCH1 signaling is required for gliogenesis, a process to generate glia cells to ensure proper brain functions. NOTCH1 signaling is down-regulated during neurogenesis and up-regulated during gliogenesis. However, the underlying mechanism remains elusive. We report here that cardiotrophin-1 (CT-1) activates NOTCH1 signaling through the up-regulation of ADAM10, a rate-limiting factor of NOTCH1 signaling activation. We found that a transcriptional factor, Myc-associated zinc finger protein (MAZ), plays an important role in ADAM10 transcription in response to CT-1 in NPCs. MAZ knockdown inhibits CT-1 stimulated gliogenesis and it can be rescued by over-expressing human NICD. Our results provide a link between NOTCH1 activation and neuronal secreted CT-1, suggesting that CT-1 plays an important role in ensuring the coordinated activation of NOTCH1 signaling during gliogenesis.

Effect of Acupuncture on the Notch Signaling Pathway in Rats with Brain Injury

OBJECTIVE

To observe the effect of acupuncture on the Notch signaling pathway in rats with traumatic brain injury and to explore the pathogenesis of acupuncture intervention on traumatic brain injury.

METHODS

Feeney's freefall epidural impact method was used to establish a traumatic brain injury model in rats; the rats were randomly divided into a normal group, sham operation group, model group and acupuncture group. Acupuncture was performed in the Baihui (DU 20), Shuigou (DU 26), Fengfu (DU 16), Yamen (DU 15) and Hegu (LI 4) acupoints in the rat, and Yamen was punctured via Fengfu. Then, the rats in each group were randomly divided into three subgroups, namely the day 3 subgroup, day 7 subgroup and day 14 subgroup according to treatment duration. The modified neurological severity scores (mNss) method was used to perform neurobehavioral scoring for evaluating the degree of injury in the rats. The hematoxylin-eosin (HE) staining method was used to observe the pathological change in the brain tissue of rats in each group. Real-time fluorescent quantitative polymerase chain reaction (Q-PCR) technology was used to detect changes in the Notch1, Hes1 and Hes5 gene expression levels in the cortex on the injured side. Western blot was used to detect the protein expression changes.

RESULTS

One day after modeling, the mNss scores in the model group and in the acupuncture group were significantly higher than those in the normal and sham operation groups (P<0.01) ; there was no statistically significant difference between the normal group and the sham operation group. The scores decreased with increased treatment time, and the scores in the acupuncture group decreased more significantly than those in the model group (P<0.01). The pathological examination by the HE staining method demonstrated that the brain tissue of the rats in the acupuncture and model groups relatively significantly changed. The Notch1 gene expression level in the acupuncture group was significantly higher than the level in all of the other groups (P<0.01) ; the Hes1 and Hes5 gene expression levels were also higher in the acupuncture group. The expression changes of the Notch1 and Hes1 protein were consistent with that of mRNA. In each experimental group, the mNss score and the pathological results by the HE staining method were consistent with the mRNA results.

CONCLUSION

Acupuncture could significantly promote high expression levels of Notch1, Hes1 and Hes5 in the brain tissue of traumatic brain injury rats. Therefore, acupuncture might be an important intervention for inducing endogenous stem cell proliferation and for promoting nerve repair.

The Roles of the Stem Cell-Controlling Sox2 Transcription Factor: from Neuroectoderm Development to Alzheimer's Disease?

Sox2 is a component of the core transcriptional regulatory network which maintains the totipotency of the cells during embryonic preimplantation period, the pluripotency of embryonic stem cells, and the multipotency of neural stem cells. This maintenance is controlled by internal loops between Sox2 and other transcription factors of the core such as Oct4, Nanog, Dax1, and Klf4, downstream proteins of extracellular ligands, epigenetic modifiers, and miRNAs. As Sox2 plays an important role in the balance between stem cells maintenance and commitment to differentiated lineages throughout the lifetime, it is supposed that Sox2 could regulate stem cells aging processes. In this review, we provide an update concerning the involvement of Sox2 in neurogenesis during normal aging and discuss its possible role in Alzheimer's disease.