| Summary: | 碩士 === 國立陽明大學 === 微生物及免疫學研究所 === 94 === CASK interacting nucleosome assembly protein (CINAP) modulates gene expression and its abundance in cultured neurons is regulated by synaptic activity. Here, we investigate whether CINAP protein levels are also regulated by synaptic stimuli in vivo. The temporal and spatial expression profiles of CINAP were examined. CINAP was widely expressed in different regions of adult mouse brain, including the cerebral cortex, hippocampus, striatum,
hypothalamus, and cerebellum. The hypothalamus is known to respond to several physiological responses, including osmotic homeostasis and feeding behaviors. Two
paradigms, salt loading and food deprivation were therefore used to observe the CINAP expression in the paraventricular nucleus (PVN) of hypothalamus. In the salt loading
paradigm, changes in osmolarity are achieved through oral administration of hypertonic saline. Compared with control mice, mice treated with hypertonic saline expressed higher
CINAP protein levels in the PVN, supporting a role of CINAP in neural response in vivo.Using confocal microscopic analysis, a significant amount of CINAP was found in the
nuclei of neurons, demonstrating that systematic dministration of salt water not only regulates protein stability of CINAP but also modulates subcellular distribution of CINAP in PVN. For the second paradigm, food deprivation for 24 hr, a significant increase of CINAP
in nuclei in the PVN was observed compared with the control group. In contrast, total protein levels of CINAP in PVN had no significant difference between these two groups of
animals. Since PVN receives synaptic input conveyed from the arcuate nucleus (ARC), a region to receive leptin signal secreted by adipose tissue, leptin was i.p. injected to the starved mice to investigate if subcellular distribution of CINAP in PVN is indirectly controlled by leptin signal. Indeed, leptin injection reduced the nuclear CINAP levels in PVN. Consistent with this observation, the number of neurons with CINAP in their nuclei was increased in ob/ob mice compared with wild type littermates. When the leptin level in ob/ob mice was restored by i.p injection of leptin, the number of neurons with nuclear CINAP was decreased. In conclusion, using salt loading and food deprivation paradigms, we demonstrate that CINAP is regulated through changes in both protein levels and subcellular distribution in PVN in the response to synaptic stimulation. In vivo transfection and establishment of
genetic mouse models will then be performed to explore the role of CINAP in neuronal response in vivo.
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