HCMV infection downregulates nidogen 1 and myelin protein zero

人巨细胞病毒感染后导致出生缺陷的细胞动力学研究 先天性感染尚不清楚。每年有1%的新生儿先天性感染巨细胞病毒。五到 这些婴儿中有10%在出生时就有症状，表现出广泛的中枢和外周症状 神经系统(CNS和PNS)障碍，包括小头畸形、精神发育迟滞和感觉神经 听力损失(SNHL)。最严重的症状可能是神经前体细胞的裂解感染。 (Npc)，如组织培养中所见。感染的神经前体细胞和神经元分化不正确/异常可能 也会导致出生缺陷。宿主对巨细胞病毒感染的免疫反应可能影响脆弱的中枢神经系统 以及妊娠期间的三叉神经节组织。然而，SNHL在婴幼儿早期的发展 出生时没有症状是令人困惑的。每年受影响的数以千计的儿童和他们的家庭 迫切需要确定巨细胞病毒引起的出生缺陷的来源，以帮助预防和 治疗。我们的长期目标是将我们的体外组织培养结果转化为阐明人巨细胞病毒 细胞间的相互作用导致了巨细胞病毒引起的出生缺陷。我们在这项建议中的目标是 确定HCMV在两个1号染色体上的特异性相互作用，以及由此导致的下调 位于1q42的NID1(NID1)和位于1q23的髓鞘蛋白0(MPZ)促进中枢神经系统和 PNS。我们发现，在感染的临床组织样本中，这两种蛋白的表达都下调。NID1是 对于发育中的大脑来说，神经元迁移和神经网络的兴奋性和可塑性是必不可少的。我们 发现表达的NID1蛋白在感染后被主动降解。人巨细胞病毒被膜蛋白的表达 Pp71在两个位点诱导断裂，并下调NID1的表达。PP71与绝缘蛋白CTCF结合 在1q42断裂点和NID1启动子。感染A型流感病毒后，NID1蛋白水平也会降低 Pp71缺失病毒(AD169del71)，表明至少有一个额外的病毒蛋白调节NID1。巨细胞病毒 两种病毒蛋白通过两条途径靶向NID1提示NID1的S消除具有很强的选择性 对病毒有利。MPZ是三叉神经节的主要神经鞘蛋白。MPZ的突变是有因果关系的 与迟发性SNHL有关。MPZ的表达仅限于三叉神经节的雪旺细胞，这似乎 不太可能为病毒提供任何选择性优势，这是MPZ监管偏离目标的有力证据。 NID1和MPZ的缺陷可能会在发育过程中产生严重的后果。我们假设人类巨细胞病毒 特异性下调NID1，通过细胞外重塑促进感染细胞的扩散 感染血管中的基质以及1q42和1q23之间的序列相似性 导致与1q23基因座的脱靶相互作用，下调MPZ，可能导致SNHL。我们 将决定1)HCMV如何下调NID1，2)HCMV从这种下调中获得的好处，3) 如果MPZ以同样的方式受到监管，4)NID和MPZ下调监管的后果是什么？

The cellular dynamics responsible for induction of birth defects following Human Cytomegalovirus (HCMV) congenital infections are unclear. Annually, 1% of newborns are congenitally infected with HCMV. Five to 10% of these infants are symptomatic at birth, displaying a broad spectrum of central and peripheral nervous system (CNS and PNS) disorders including microcephaly, mental retardation, and sensorineural hearing loss (SNHL). The most severe manifestations may be due to lytic infection of neural progenitor cells (NPCs), as seen in tissue culture. The improper/abnormal differentiation of infected NPCs and neurons may also contribute to birth defects. The host immune response to HCMV infection may impact delicate CNS and PNS tissues during gestation. However, the development of SNHL during early childhood in infants asymptomatic at birth is perplexing. For the thousands of children and their families affected annually there is a critical need to determine the source of HCMV-induced birth defects to aid in their prevention and treatment. Our long term goal is to translate our in vitro tissue culture findings into elucidating HCMV's cellular interactions contributory to HCMV-induced birth defects. Our objective in this proposal is to determine if HCMV's specific interactions at two chromosome 1 loci, and the resulting downregulation of nidogen 1 (NID1) at 1q42 and myelin protein zero (MPZ) at 1q23, promote malfunctions in the CNS and PNS. We find expression of both proteins is downregulated in infected clinical tissue samples. NID1 is essential to the developing brain for neuronal migration and neural network excitability and plasticity. We find expressed NID1 protein is actively degraded post infection. Expression of the HCMV tegument protein pp71 induces breaks at both sites and downregulates NID1. pp71 and the insulator protein CTCF are bound at the 1q42 breaksite and the NID1 promoter. NID1 protein levels are also reduced after infection with a pp71 deletion virus (AD169del71), indicating at least one additional viral protein regulates NID1. HCMV targets NID1 with two viral proteins via two pathways suggesting NID1's elimination delivers strong selective advantage to the virus. MPZ is the principal nerve sheath protein of the PNS. Mutations in MPZ are causally linked to late onset SNHL. MPZ expression being limited solely to Schwann cells of the PNS, which seems unlikely could offer any selective advantage to the virus, is strong evidence that MPZ regulation is off-target. Deficiencies in NID1 and MPZ could have severe ramifications during development. We hypothesize HCMV specifically downregulates NID1 to promote dispersal of infected cells via remodeling of the extracellular matrix in infected blood vessels and that similarity in sequence shared between the 1q42 and1q23 sites leads to an off-target interaction with the 1q23 locus, downregulating MPZ, potentially leading to SNHL. We will determine 1) how HCMV downregulates NID1, 2) the benefit HCMV derives from this downregulation, 3) if MPZ is regulated in the same manner and 4) what are the ramifications of NID and MPZ downregulation?