Functional significance of Siglec-6, a novel leptin receptor, in human placental

描述(申请人提供)：先兆子痫(PE)是一种妊娠特有的疾病，每年在全球范围内导致50-76,000名产妇死亡。美国15%的早产是由PE引起的，占新生儿发病率和死亡率的很大比例。可归因于私募股权投资的直接美国医疗保健成本估计为每年70亿美元。PE的发病机制被认为始于妊娠早期，细胞滋养细胞(CTB)的间质和血管内侵袭受损进入母体组织。我们最近研究了胎盘基板(CTB侵袭区)在合并PE的妊娠中的基因表达谱，确定了55个在PE中与对照组相比差异表达的基因，包括40多个新的靶点。我们的长期目标是确定这些差异表达的基因是否在CTB生物学中发挥关键作用，特别是它们在间质和血管内侵袭中的作用以及它们在PE早期阶段的作用。对于这一建议，我们集中在两个差异表达的基因-瘦素和Siglec-6(唾液酸结合Ig类似凝集素6)-在滋养层侵袭中的作用。Siglec-6最初被克隆为瘦素结合蛋白(OB-BP1)，其胞内尾部含有一个保守的免疫受体酪氨酸抑制基序(ITIM)和一个类似于ITIM的基序，提示Siglec-6具有潜在的信号转导功能。虽然所有研究的灵长类动物的B淋巴细胞都表达Siglec-6，但只有人类胎盘表达Siglec-6，这很有趣，因为PE是一种人类特有的疾病，依赖于胎盘。有趣的是，典型的瘦素受体(OBR)在我们的PE微阵列数据中没有差异表达，这表明Siglec-6可能是PE中关键的瘦素受体。此外，我们已经证实瘦素在体外可以促进人CTB的侵袭，而Siglec-6的表达可以在CTB细胞系中消除这一影响。这些观察结果导致了我们的总体假设，即Siglec-6的过度表达通过作为一种抑制瘦素受体的功能来削弱CTB的侵袭，在PE的发病机制中发挥作用。在这个提案中，我们将通过回答以下问题来验证Siglec-6过表达通过改变OBR信号来抑制瘦素促进CTB分化和侵袭的假设：目的1.Siglec-6是否抑制Leptin促进人CTB侵袭？目的2：Siglec-6的表达是否影响了OBR信号通路对人类CTB侵袭的影响？目的3：在CTB的分化和侵袭过程中，Siglec-6的表达改变了OBR信号的哪些下游靶点？发现PE相关分子Leptin和Siglec-6如何调控CTB侵袭，将决定它们在早期PE发病机制中的潜在作用。最终，了解调控滋养层侵入的复杂途径将提供所需的洞察力，以开发针对这一严重妊娠疾病的原因而不是后果的新的预防、诊断和/或治疗策略，从而改善每年患有PE的800万母婴夫妇的健康。 与公共卫生相关：先兆子痫是一种影响4%至8%的孕妇的疾病，是全球孕妇死亡的主要原因。患有子痫前期(PE)的妇女在怀孕后半段会出现肿胀和高血压，可能会发展为中风、心脏病发作、肝功能障碍或癫痫。对于婴儿来说，PE可能会导致发育障碍或死产。那些存活下来的婴儿成年后患疾病的风险增加，包括糖尿病和心脏病。

DESCRIPTION (provided by applicant): Preeclampsia (PE) is a pregnancy-specific disease that accounts for significant morbidity and 50-76,000 maternal deaths annually worldwide. Fifteen percent of all US preterm births result from PE, accounting for significant neonatal morbidity and mortality. The immediate US health care costs attributable to PE are estimated at $7 billion per year. PE pathogenesis is thought to begin in the first half of pregnancy with impaired interstitial and endovascular invasion of cytotrophoblasts (CTBs) into the maternal tissue. We recently examined the gene expression profile of the placental basal plate, the region of CTB invasion, in pregnancies complicated by PE, identifying 55 genes that are differentially expressed in PE compared to controls including over 40 novel targets. Our long-range goal is to determine whether these differentially expressed genes play key roles in CTB biology, specifically their role in interstitial and endovascular invasion and their contribution to the early stages of PE. For this proposal, we focus the roles of on two of the differentially expressed genes- leptin and Siglec-6 (sialic acid binding Ig like lectin 6) - in trophoblast invasion. Siglec-6 was originally cloned as a leptin binding protein (OB-BP1) with an intracellular tail containing a conserved immunoreceptor tyrosine-based inhibitory motif (ITIM) and an ITIM-like motif, suggesting that Siglec-6 has signaling potential. While the B lymphocytes of all studied primates express Siglec-6, only human placenta expresses Siglec-6, which is intriguing given PE is a human-specific disease dependent upon the placenta. Interestingly, the canonical leptin receptors (ObR) were not differentially expressed in our PE microarray data suggesting that Siglec-6 may serve as the critical leptin receptor in PE. Additionally, we have established that leptin can promote human CTB invasion in vitro and that Siglec-6 expression can abrogate this effect in CTB cell lines. These observations lead to our overall hypothesis that overexpression of Siglec-6 plays a role in PE pathogenesis by functioning as an inhibitory leptin receptor to impair CTB invasion. In this proposal we will test the hypothesis that Siglec-6 overexpression inhibits leptin promotion of CTB differentiation and invasion by altering ObR signaling by answering the following questions: Aim 1. Does Siglec-6 inhibit leptin promotion of human CTB invasion? Aim 2: Are the ObR signaling pathways critical for human CTB invasion modified by Siglec-6 expression? Aim 3: What downstream targets of ObR signaling are altered by Siglec-6 expression during CTB differentiation and invasion? Discovering how the PE-associated molecules leptin and Siglec-6 regulate CTB invasion will determine their potential role in early PE pathogenesis. Ultimately, understanding the complex pathways that regulate trophoblast invasion will provide the insights needed to develop novel preventative, diagnostic and/or treatment strategies geared at the cause rather than the consequences of this serious pregnancy disease, thereby improving the health of the 8 million woman-infant pairs annually afflicted by PE. PUBLIC HEALTH RELEVANCE: Preeclampsia is a disorder that affects four to eight percent of pregnancies and is a leading cause of death among pregnant women worldwide. Women with preeclampsia (PE) experience swelling and high blood pressure in the second half of pregnancy that can progress to stroke, heart attack, liver dysfunction, or seizure. For the baby, PE can cause growth failure or stillbirth. Those babies that do survive have an increased risk of disorders as adults including diabetes and heart disease.