Expression profile of heat shock response factors during hookworm larval activation and parasitic development.
Expression profile of heat shock response factors during hookworm larval activation and parasitic development.
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DOI：
10.1016/j.molbiopara.2015.08.003
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发表时间：
2015-07
影响因子：
1.5
通讯作者：
Hawdon JM
中科院分区：
文献类型：
--
作者：
Gelmedin V;Delaney A;Jennelle L;Hawdon JM
当生物体暴露于温度升高时，它们经历由转录因子热休克因子1（HSF-1）调节的热休克反应（HSR）。热休克反应包括由HSF-1与热休克基因启动子中的反应元件结合引发的基因表达的快速变化。热休克蛋白作为分子伴侣在高温和其他应激期间保护蛋白质。在感染期间，钩虫感染性第三期幼虫（L3）经历从环境温度到宿主温度的温度转变。这种升高的温度是恢复进食和激活L3所必需的，但这种升高是否引发热休克反应尚不清楚。为了研究热休克在钩虫L3激活和寄生虫发育中的作用，我们确定并表征了钩虫钩虫中热休克反应的几个组分的表达谱。我们克隆了编码hsp 70家族成员（HSP-hsp-1）和hsp 90家族成员（HSP-daf-21）的DNA。暴露于42 °C的热休克1小时导致两种基因的显著上调，在22 °C下1小时衰减后缓慢恢复到接近基线水平。两个基因都没有响应宿主温度（37 °C）而上调。相反，hsf-1的水平在热休克期间保持不变，但在37°C孵育时增加。在激活过程中，hsp-1和daf-21都在早期下调，尽管daf-21水平在未激活的对照幼虫中在孵育12小时后显著增加，而在激活的幼虫中在孵育24小时后略有增加。测试了热休克反应调节剂雷公藤红素和KNK 437在热休克和活化期间对基因表达的影响。雷公藤红素，一种促进热休克基因表达的HSP 90抑制剂，在热休克过程中轻微上调HSP-1和DAF-21的表达。KNK 437是一种热休克蛋白表达抑制剂，在相似的条件下略微下调了这两个基因。这两种调节剂抑制激活相关的喂养，但都没有在16小时激活L3的HSP-1水平的影响。雷公藤红素和KNK 437均阻止在活化期间在未活化的对照幼虫中观察到的daf-21和hsf-1的上调，并显著下调活化幼虫中HSF-1负调节因子hsb-1的表达。在发育中的A. ceylanicum幼虫从感染的宿主中回收，发现与活化的L3的表达谱显著不同，表明在体外活化期间的摄食与寄生虫发育不同。我们的研究结果表明，一个经典的热休克反应是不诱导在主机温度和抑制幼虫恢复和寄生虫在主机中的发展，但部分热休克反应诱导后，在主机温度下延长孵育的情况下，一个发展的信号，可能是保护免受热应激。
When organisms are exposed to an increase in temperature, they undergo a heat shock response (HSR) regulated by the transcription factor heat shock factor 1 (HSF-1). The heat shock response includes the rapid changes in gene expression initiated by binding of HSF-1 to response elements in the promoters of heat shock genes. Heat shock proteins function as molecular chaperones to protect proteins during periods of elevated temperature and other stress. During infection, hookworm infective third stage larvae (L3) undergo a temperature shift from ambient to host temperature. This increased temperature is required for the resumption of feeding and activation of L3, but whether this increase initiates a heat shock response is unknown. To investigate the role of the heat shock in hookworm L3 activation and parasitic development, we identified and characterized the expression profile of several components of the heat shock response in the hookworm Ancylostoma caninum. We cloned DNAs encoding an hsp70 family member (Aca-hsp-1) and an hsp90 family member (Aca-daf-21). Exposure to a heat shock of 42 °C for one hour caused significant up-regulation of both genes, which slowly returned to near baseline levels following one hour attenuation at 22 °C. Neither gene was up-regulated in response to host temperature (37 °C). Conversely, levels of hsf-1 remained unchanged during heat shock, but increased in response to incubation at 37°C. During activation, both hsp-1 and daf-21 are down regulated early, although daf-21 levels increase significantly in non-activated control larvae after 12 hours, and slightly in activated larvae by 24 hours incubation. The heat shock response modulators celastrol and KNK437 were tested for their effects on gene expression during heat shock and activation. Pre-incubation with celastrol, an HSP90 inhibitor that promotes heat shock gene expression, slightly up-regulated expression of both hsp-1 and daf-21 during heat shock. KNK437, an inhibitor of heat shock protein expression, slightly down regulated both genes under similar conditions. Both modulators inhibited activation-associated feeding, but neither had an effect on hsp-1 levels in activated L3 at 16 hours. Both celastrol and KNK437 prevent the up-regulation of daf-21 and hsf-1 seen in non-activated control larvae during activation, and significantly down regulated expression of the HSF-1 negative regulator Aca-hsb-1 in activated larvae. Expression levels of heat shock response factors were examined in developing A. ceylanicum larvae recovered from infected hosts and found to differ significantly from the expression profile of activated L3, suggesting that feeding during in vitro activation is regulated differently than parasitic development. Our results indicate that a classical heat shock response is not induced at host temperature and is suppressed during larval recovery and parasitic development in the host, but a partial heat shock response is induced after extended incubation at host temperature in the absence of a developmental signal, possibly to protect against heat stress.