Identification of a signal sequence necessary for the unconventional secretion of Engrailed homeoprotein
Identification of a signal sequence necessary for the unconventional secretion of Engrailed homeoprotein
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DOI：
10.1016/s0960-9822(07)00346-6
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发表时间：
1998-07-16
期刊：
影响因子：
9.2
通讯作者：
Prochiantz, A
中科院分区：
文献类型：
--
作者：
Joliot, A;Maizel, A;Prochiantz, A
背景：Engrailed-land Engrailed-2是与离散结构的形态发生有关的同源蛋白转录因子。嵌入蛋白在大鼠胚胎中脑-后脑细胞细胞核中表达，并参与中脑-后脑区域的定形。我们之前已经发现内源性和外源性表达的Engrailed蛋白也与信号转导和分泌相关的膜区有关。在总膜组分中，Engrailed蛋白的一小部分（约5%）能抵抗蛋白酶K蛋白水解，这表明Engrailed蛋白可以进入管腔室。再加上我们发现同质结构域和同质蛋白可以被活细胞内化，这些观察结果表明Engrailed可能作为多肽信使。为了研究这种可能性，我们研究了Engrailed是否可以被分泌。结果：在COS细胞中嵌入的表达可以在相邻的原代神经元中恢复，这依赖于其同源域的短序列，与“经典”分泌信号不同。该序列与内化所需的序列重叠，并且在同型蛋白中高度保守，是分泌所需的“非常规”序列的第一个例子。只有不到5%的细胞内Engrailed蛋白被分泌，其分泌量与进入膜室之间存在相关性，在膜室中，Engrailed蛋白受到蛋白酶K的保护。结论：我们的研究结果支持Engrailed蛋白和其他同型蛋白可能作为细胞间多肽信使的说法。
Background: Engrailed-land Engrailed-2 are homeoproteins - transcription factors implicated in the morphogenesis of discrete structures. Engrailed proteins have a role in patterning the midbrain-hindbrain region and are expressed in the nuclei of rat embryo midbrain-hindbrain cells. We have previously found that both endogenous and exogenously expressed Engrailed proteins also associate with membrane regions implicated in signal transduction and secretion. Within total membrane fractions, a small proportion of Engrailed - about 5% - is protected against proteinase K proteolysis, suggesting that Engrailed has access to a luminal compartment. Together with our finding that homeodomains and homeoproteins can be internalized by live cells, these observations suggest that Engrailed might act as a polypeptidic messenger. In order to investigate this possibility, we looked to see if Engrailed could be secreted.Results: Engrailed expressed in COS cells can be recovered in abutting primary neurons and this is dependent on a short sequence in its homeodomain distinct from 'classical' secretion signals. This sequence, which overlaps with the sequence necessary for Engrailed internalization and which is highly conserved among homeoproteins, is the first example of an 'unconventional' sequence necessary for secretion. Less than 5% of total intracellular Engrailed is secreted and there is a correlation between secretion and access to the membrane compartment where the protein is protected against proteinase K,Conclusions: Our results lend weight to the proposal that Engrailed, and possibly other homeoproteins, might act as intercellular polypeptidic messengers.