Ifitm基因是一群可被干擾素刺激表現的基因，目前已知這些基因參與細胞對病毒的防禦，然而其生化特性及這些基因參與的其他生物功能並不清楚。將這些基因敲除後小鼠會產生過度攝食的行為並會造成肥胖，同時在下視丘中黑皮質素的前驅物POMC的表現量顯著降低，此發現表明破壞Ifitm基因可導致下視丘功能被破壞。然而由於代謝的調控並非只由下視丘控制，Ifitm基因是否直接參與下視丘的功能並不清楚。本研究卽是在探討Ifitm基因是否在下視丘的功能中扮演重要的角色。我們首先透過與下視丘功能有關的行為分析測試是否有其他下視丘功能被破壞的證據。我們發現在IFITM基因剔除公鼠，3-6個月開始出現過度攝食的行為與體重明顯增加；然而IFITM基因剔除母鼠在18個月後才出現同樣的表現型。IFITM基因剔除公鼠，在OFT與FST的行為測試中行動力下降，IFITM基因剔除母鼠卻有較多的活動；在公鼠與母鼠中焦慮均顯著增加。我們進一步測試這些剔除鼠的下視丘組織及神經胜肽的表現，在組織分析中並沒有發現組織結構異常。在神經胜肽的分析中IFITM基因剔除鼠的CRF的表現量增加，與IFITM基因剔除鼠的焦慮行為顯示相同趨勢。POMC表現的減少與CRF表現的上升顯示下視丘的功能紊亂。我們同時發現IFITM基因剔除鼠中微膠細胞數增加，以及位於下視丘的細胞本體的體積增加。另外IFITM基因剔除鼠中的細胞激素TNF-α與IL-1β在周邊血清中的增加表明此剔除鼠的下視丘產生發炎。本研究發現剔除IFITM基因會造成多項下視丘功能受到影響，並發現此突變鼠有下視丘發炎的現象。此下視丘發炎是否為下視丘功能破壞的主因，及IFITM基因剔除鼠的下視丘功能異常的細胞分子機制將會進一步被分析。 / Ifitm genes are a group of interferon-inducible genes, best known for their antiviral roles. Their biological functions other than cellular antivirus and the biochemical properties of these proteins are not well-understand. Previously age-dependent hyperphagia and obesity were reported in IfitmDel mutant mice, in which 5 Ifitm genes were deleted. The levels of pro-opiomelanocortin (POMC) in hypothalamus of these mice were significantly reduced, suggesting that the hyperphagia phenotype of IfitmDel mutants is caused by defective central melanocortin signaling. In this study, we examine whether the hypothalamic dysfunctions are developed in these mutants. Whether hypothalamus associated behaviors are disrupted in IfitmDel mutants was first examined. We discovered that the hyperphagia and obesity phenotype in IfitmDel mutants are gender-dependent. These phenotypes in male mutants are detectable starting from 4-6 months of age, but not detected until one-year old in female mutants. Male mutants reveal the trends of decreased activities, while female mutants exhibit increased locomotor activity. Both gender develop anxiety-like phenotype. The behavioral abnormalities support the hypothesis of hypothalamic dysfunctions. As the Ifitm genes are expressed in various stage during development, the anatomy and the functions of the hypothalamus of these mutants were further tested. The histological analyses show no anatomical defects, neuron count differences and morphological alterations of neurons in IfitmDel mutant brains of both genders. These results indicate that these proteins are rather crucial for maintaining normal physiology in the developed central nervous system (CNS). The expression levels of neuropeptides related to stress response and anxiety or depression status, such as corticotrophin releasing factor (CRF), are altered in mutant hypothalamus. In contrast, Cell count and cell body size of microglia, whereas sera levels of pro-inflammatory cytokines, including TNF-α and IL-1β are elevated in IfitmDel mice, indicating hypothalamic inflammation and microglial activation phenotypes. The cellular mechanisms underlying the hypothalamic dysfunctions and the causative relationship of the hypothalamic inflammation with these phenotypes shall be further explored in the future studies.
| Identifer | oai:union.ndltd.org:CHENGCHI/G1027540041 |
| Creators | 林万焜, Lin, Wan-Kun |
| Publisher | 國立政治大學 |
| Source Sets | National Chengchi University Libraries |
| Language | 英文 |
| Detected Language | English |
| Type | text |
| Rights | Copyright © nccu library on behalf of the copyright holders |
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