Signal peptides and growth factor signaling

信号序列将新翻译的蛋白质定位于细胞内外的特定位置，以及 因此，在细胞生物学中扮演着关键的角色。除了其经典的目标函数外，许多非 近年来已经报道了特定信号肽的典型功能，主要是在低等生物中， 而且在真核细胞中也是如此。然而，关于信号序列的生物学仍有许多需要了解的地方， 它们已成为药物开发的新焦点。血管内皮细胞生长因子(VEGF)是 原型性生长因子在血管生成中的作用，这是发育、生长、成体动态平衡和 对损伤的反应，这在包括缺血相关的一系列疾病中都是失调的 心血管疾病、糖尿病视网膜病变和恶性肿瘤。血管内皮生长因子的作用主要是由其介导的 与血管内皮生长因子受体(VEGFR)-2的高亲和力结合，触发几个下游信号的激活 小路。这是一个严格控制的过程，有多层监管，以确保信号得到精细调谐。 血管内皮细胞和平滑肌细胞衍生的神经粘蛋白样蛋白(DCBLD2)是一种完整的膜蛋白 具有异常长的两个子域的组织信号序列。我们已将DCBLD2确定为 血管内皮生长因子信号调节因子与发育和缺血血管生成。DCBLD2与VEGFR合作- 2，通过调节VEGFR-2-VE-钙粘蛋白-蛋白酪氨酸磷酸酶复合体来调节血管内皮生长因子信号转导 队形。在寻找参与其与VEGFR-2相互作用的DCBLD2结构域(S)时，我们意外地发现 DCBLD2信号序列与VEGFR-2之间的功能相互作用。DCBLD2信号序列 在培养物中表达或添加含有其疏水C-末端部分的合成肽 细胞促进血管内皮细胞生长因子信号转导。这导致我们假设DCBLD2信号序列调节 血管内皮生长因子(以及可能的其他生长因子)信号转导和调节血管生成，也提高了 其他类似结构的信号序列可能在生长因子信号转导中发挥调节作用。 在这里，我们试图扩大这些观察的范围，以定义和确定， DCBLD2信号序列对血管内皮生长因子及相关信号通路的后靶向作用。为此， 我们的具体目的是研究DCBLD2信号序列在血管内皮生长因子信号中的非规范功能 外源性DCBLD2信号序列相关肽对血管内皮细胞生长因子的影响 信号和血管生成。所提出的实验建立了一种新的信号后定向函数 生长因子信号转导中的序列，为信号序列的未来发展奠定了基础 以治疗为基础的疗法，不仅针对血管生成，还可能针对其他疾病。

Signal sequences target newly translated proteins to specific locations within and outside the cell, and accordingly, play a key role in cell biology. Beyond their classical targeting functions, a number of non- canonical functions of specific signal peptides have been reported in recent years, mostly in lower organisms, but also in eucaryotic cells. However, much remains to be learned regarding the biology of signal sequences, which have emerged as a new focus for drug development. Vascular endothelial growth factor (VEGF) is the prototypic growth factor in angiogenesis, a key process during development, growth, adult homeostasis, and response to injury, which is dysregulated in a broad spectrum of diseases, including ischemia-related cardiovascular diseases, diabetic retinopathy and malignancy. The VEGF effects are primarily mediated by its high affinity binding to VEGF receptor (VEGFR)-2 which triggers activation of several downstream signaling pathways. This is a tightly controlled process with multiple layers of regulation to ensure a finely tuned signal. Endothelial and smooth muscle cell-derived neuropilin-like protein (DCBLD2) is an integral membrane protein with an unusually long, two-subdomain organization signal sequence. We have identified DCBLD2 as a regulator of VEGF signaling and developmental and ischemic angiogenesis. DCBLD2 associates with VEGFR- 2 and regulates VEGF signaling by modulating VEGFR-2-VE-cadherin-protein tyrosine phosphatase complex formation. In search of DCBLD2 domain(s) involved in its interaction with VEGFR-2, unexpectedly we identified a functional interaction between the DCBLD2 signal sequence and VEGFR-2. DCBLD2 signal sequence expression, or addition of a synthetic peptide encompassing its hydrophobic, C-terminal moiety to cultured cells promoted VEGF signal transduction. This led us to hypothesize that DCBLD2 signal sequence regulates VEGF (and possibly other growth factors’) signal transduction and modulates angiogenesis, also raising the possibility that other similarly structured signal sequences may play a regulatory role in growth factor signaling. Here, we seek to expand the scope of these observations to define, and determine the mechanism of action of, the post-targeting functions of DCBLD2 signal sequence on VEGF and related signaling pathways. To this end, our specific aims are to investigate non-canonical functions of DCBLD2 signal sequence in VEGF signal transduction and evaluate the effects of exogenous DCBLD2 signal sequence-related peptides on VEGF signaling and angiogenesis. The proposed experiments establish a novel post-targeting function for signal sequences in growth factor signal transduction and set the stage for future development of signal sequence- based therapeutics, not only for angiogenesis, but potentially other disorders.