Humanin (HN) is an anti-apoptotic peptide that suppresses neuronal cell death induced by Alzheimer's disease, prion protein fragments, and serum deprivation. Recently, we demonstrated that Gly14-HN (HNG), a variant of HN in which the 14th amino acid serine is replaced with glycine, can decrease apoptotic neuronal death and reduce infarct volume in a focal cerebral ischemia/reperfusion mouse model. In this study, we postulate that the mechanism of HNG's neuroprotective effect is mediated by the PI3K/Akt pathway. Oxygen-glucose deprivation (OGD) was performed in cultured mouse primary cortical neurons for 60 min. The effect of HNG and PI3K/Akt inhibitors on OGD-induced cell death was examined at 24 h after reperfusion. HNG increased cell viability after OGD in primary cortical neurons, whereas the PI3K/Akt inhibitors wortmannin and Akti-1/2 attenuated the protective effect of HNG. HNG rapidly increased Akt phosphorylation, an effect that was inhibited by wortmannin and Akti-1/2. Mouse brains were injected intraventricularly with HNG before being subjected to middle cerebral artery occlusion (MCAO). HNG treatment significantly elevated p-Akt levels after cerebral I/R injury and decreased infarct volume. The protective effect of HNG on infarct size was attenuated by wortmannin and Akti-1/2. Taken as a whole, these results suggest that PI3K/Akt activation mediates HNG's protective effect against hypoxia/ischemia reperfusion injury.

Although human congenital cerebellar malformations are common, their molecular and developmental basis is still poorly understood. Recently, cilia-related gene deficiencies have been implicated in several congenital disorders that exhibit cerebellar abnormalities such as Joubert syndrome, Meckel-Gruber syndrome, Bardet-Biedl syndrome, and Orofaciodigital syndrome. The association of cilia gene mutations with these syndromes suggests that cilia may be important for cerebellar development, but the nature of cilia involvement has not been elucidated. To assess the importance of cilia-related proteins during cerebellar development, we studied the effects of CNS-specific inactivation of two mouse genes whose protein products are critical for cilia formation and maintenance, IFT88, (also known as polaris or Tg737), which encodes intraflagellar transport 88 homolog, and Kif3a, which encodes kinesin family member 3a. We showed that loss of either of these genes caused severe cerebellar hypoplasia and foliation abnormalities, primarily attributable to a failure of expansion of the neonatal granule cell progenitor population. In addition, granule cell progenitor proliferation was sensitive to partial loss of IFT function in a hypomorphic mutant of IFT88 (IFT88orpk), an effect that was modified by genetic background. IFT88 and Kif3a were not required for the specification and differentiation of most other cerebellar cell types, including Purkinje cells. Together, our observations constitute the first demonstration that cilia proteins are essential for normal cerebellar development and suggest that granule cell proliferation defects may be central to the cerebellar pathology in human cilia-related disorders.

Effects of substance P (SP) and selective tachykinin agonists on neurotransmission at guinea-pig intracardiac ganglia were studied in vitro. Voltage responses of neurons to superfused tachykinins and nerve stimulation were measured using intracellular microelectrodes. Predominant effects of SP (1 μM) were to cause slow depolarization and enable synaptic transmission at low intensities of nerve stimulation. Augmented response to nerve stimulation occurred with 29 of 40 intracardiac neurons (approx. 73%). SP inhibited synaptic transmission at 23% of intracardiac neurons but also caused slow depolarization. Activation of NK3 receptors with 100 nM [MePhe 7]neurokinin B caused slow depolarization, enhanced the response of many intracardiac neurons to low intensity nerve stimulation or local application of acetylcholine, and triggered action potentials independent of other stimuli in 6 of 42 neurons. The NK1 agonist [Sar 9,Met(O2)11]SP had similar actions but was less effective and did not trigger action potentials independently. Neither selective agonist inhibited cholinergic neurotransmission. We conclude that SP can function as a positive or negative neuromodulator at intracardiac ganglion cells, which could be either efferent neurons or interneurons. Potentiation occurs primarily through NK3 receptors and may enable neuronal responses with less preganglionic nerve activity. Inhibition of neurotransmission by SP is most likely explained by the known blocking action of this peptide at ganglionic nicotine receptors.

Yukako Hattori, Tadao Usui, Daisuke Satoh, Sanefumi Moriyama, Kohei Shimono, Takehiko Itoh, Katsuhiko Shirahige, Tadashi Uemura, Sensory-Neuron Subtype-Specific Transcriptional Programs Controlling Dendrite Morphogenesis: Genome-wide Analysis of Abrupt and Knot/Collier, Developmental Cell, Volume 27, Issue 5, 9 December 2013, Pages 530-544, ISSN 1534-5807 / 京都大学 / 0048 / 新制・課程博士 / 博士(生命科学) / 甲第18418号 / 生博第298号 / 新制||生||39(附属図書館) / 31276 / 京都大学大学院生命科学研究科統合生命科学専攻 / (主査)教授 上村 匡, 教授 西田 栄介, 教授 荒木 崇 / 学位規則第4条第1項該当 / Doctor of Philosophy in Life Sciences / Kyoto University / DFAM

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Stress plays a significant role in neural development and brain function. To better understand the mechanisms underlying the impact of stress on brain development and neuroendocrine function, this study focuses on the phenylethanolamine-N-methyltransferase (Pnmt) enzyme as a key mediator of stress hormone signaling. Pnmt is activated as part of a positive feedback mechanism during stress to convert norepinephrine to epinephrine and amplify the sympathetic response. Most of our knowledge about Pnmt is derived from its role in the systemic production of epinephrine from adrenal chromaffin cells, but it is also known to be expressed in the central nervous system, including the brainstem, retina, hypothalamus, and cerebellum. Given the importance of the central nervous system in modulating stress responses, this project sought to investigate cellular Pnmt expression in the central nervous system using a genetic-marking strategy with a Pnmt-Cre-recombinase knock-in driver strain (Pnmt+/Cre) and a β-galactosidase (βGal) reporter strain (R26R+/βGal) in parallel with Pnmt-specific immunofluorescent histochemical staining to identify Pnmt+ cells in the adult mouse cerebellum, hypothalamus, and cerebral cortex. The results show extensive patterns of active and historical Pnmt protein expression throughout the cerebellum and hypothalamus, with significant neuropeptide Y co-expression in the hypothalamus and considerable historical Pnmt expression throughout the cerebral cortex. To quantify baseline Pnmt mRNA levels across embryonic and postnatal neural development and elucidate differential Pnmt isoform expression through tissue-specific regulation in the developing brain, quantitative polymerase chain reaction (qPCR) was performed in the brainstem, cerebellum, and cerebral cortex with isoform-specific primers. Initial results show a developmental, tissue-specific Pnmt isoform shift between embryonic and postnatal neural development by an intron-retention alternative splicing mechanism. Ultimately, these findings provide an anatomical "blueprint" for investigating the role of central nervous system Pnmt expression in health and disease, and emphasize the role of Pnmt in early neural development, illustrating how stress impacts the formation of neural connections during formative periods of brain maturation.

This study demonstrates the direct delivery of plasmid gene constructs into spinal motor neurons utilizing retrograde axoplasmic transport. The plasmid vectors contained the Lac Z gene under the control of both the Rous sarcoma virus (RSV) and Simian virus (SV)40 promoters. β-Galactosidase expression was observed in α and γ motor neurons by histochemical staining following direct injection into the sciatic nerve or gastrocnemius muscle. The presence of LacZ gene constructs was confirmed by the polymerase chain reaction (PCR). The ability to introduce gene constructs into motor neurons allows for the study of gene regulation and permits the development of gene therapy strategies for motor neuron diseases including the spinal muscular atrophies (SMA) and amyotrophic lateral sclerosis (ALS).

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