Physiological and pathological functions of E3 ubiquitin ligases Smurfs

E3泛素连接酶Smurfs的生理和病理功能

基本信息

批准号：
8763379
负责人：
YING E Zhang
金额：
$ 70.04万
依托单位：
DIVISION OF BASIC SCIENCES - NCI
依托单位国家：
美国
项目类别：
财政年份：
资助国家：
美国
起止时间：
至
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/8763379
关键词：
Address Adult Age-Related Bone Loss Alleles Attenuated Biological Breast Cancer Cell Cell Cycle Progression Cell Nucleus Cell physiology Cytoplasm DNA Repair DNA biosynthesis Embryo Embryonic Development Enzymes Epigenetic Process Epithelial Excision Family Genome Stability Homeostasis In Vitro Inflammatory Response Knock-out Knockout Mice Literature Malignant Neoplasms Modification Mono-S Mus Mutation Neoplasm Metastasis Nude Mice Null Lymphocytes Osteoblasts Osteoporosis Pathway interactions Physiological Play Process Proteasome Inhibitor Proteins Regulation Reporting Research Role Signal Transduction Staging Substrate Specificity System Therapeutic Uses Tissues Transforming Growth Factor beta Tumor Suppressor Proteins Ubiquitin Ubiquitin-Activating Enzymes Ubiquitination Work base bone cell motility chromatin remodeling gamma-Glutamyl Hydrolase histone modification in vivo malignant breast neoplasm member migration mouse model multicatalytic endopeptidase complex novel overexpression protein degradation recombinase success tumor tumor progression tumorigenesis ubiquitin-protein ligase

项目摘要

Smad ubiquitin regulatory factors (Smurfs) are members of the HECT family of E3 ubiquitin ligases. Two Smurfs, Smurf1 and Smurf2, were identified based on their activities to modulate TGF-beta/BMP signaling by promoting ubiquitin modification on Smads; however, subsequent studies have expanded the repertoire of Smurf substrates to include proteins such as RhoA, Runx2 and MEKK2 outside the TGF-beta/BMP pathway. To address the physiological function of Smurfs, we have generated mice lacking either Smurf1 or Smurf2. We found that these two paralogous E3 ubiquitin ligases have both common and unique functions during embryogenesis and in maintaining adult physiological homeostasis. Our earlier work on characterizing Smurf1 knockout mice revealed a novel mechanism in regulating osteoblast function and bone homeostasis, suggesting that targeting Smurf1 may prove to be an effective strategy for treating age-related bone losses in osteoporosis. Our more recent work on characterizing Smurf2 knockout mice clarified contradictory reports in the literature about Smurf regulation of TGF-beta signaling by showing that Smurf2 indeed has an inhibitory role, but it does so by attenuating Smad3 activity through mono-ubiquitination rather than promoting its degradation as previously reported. Because loss of both Smurfs leads to embryonic lethality, we have created a conditional Smurf2 knockout allele, which enabled us to investigate physiological functions of Smurfs by completely removal of all Smurf activities in desired tissues using tissue-specific expression of cre recombinase and obtain conditional Smurf null cells from late stages embryos or adult tissues. Our study of Smurf2 knockout mice also led to an unexpected discovery of a previously unrecognized function of Smurf2 as a tumor suppressor that normally maintains genomic stability by controlling epigenetic landscape of histone modifications. We found that Smurf2 interacts with a group of proteins that regulate DNA replication, chromatin remodeling and histone modification. We are currently validating these findings using in vitro and in vivo approaches and to investigate the biological relevance of these interactions in genomic stability and tumorigenesis. Consistent with the tumor suppresser function of Smurf2, we found that Smurf2 expression is decreased in the nucleus but increased in the cytoplasm of breast cancer cells. Smurf1 expression is also upregulated in the cytoplasm of the breast cancer cells. Overexpression of Smurf1 and Smurf2 promotes metastasis in nude mouse models and induces epithelial-to-mesenmchymal transition, migration, and invasion of breast cancer cells, suggesting that Smurfs play important roles in breast cancer progression. We are currently studying the mechanism underpinning the role of Smurf1 and Smurf2 promoting breast cancer cell migration and invasion.

Smad泛素调节因子（蓝精灵）是E3泛素连接酶家族的成员。根据它们的活动，通过促进SMADS上的泛素修饰来调节TGF-beta/bmp信号传导的活动，以调节TGF-beta/bmp信号传导，确定了两个蓝精灵。但是，随后的研究将SMURF底物的曲目扩展到了TGF-BETA/BMP途径之外的蛋白质，例如RhoA，Runx2和Mekk2。为了解决蓝精灵的生理功能，我们产生了缺乏蓝精神或蓝精神的小鼠。我们发现，这两个副E3泛素连接酶在胚胎发生和维持成人生理稳态时具有常见和独特的功能。我们较早的表征SMURF1敲除小鼠的工作揭示了调节成骨细胞功能和骨稳态方面的一种新型机制，这表明靶向SMURF1可能被证明是治疗骨质疏松症中与年龄相关的骨骼损失的有效策略。我们在描述Smurf2敲除小鼠的最新研究中阐明了文献中有关TGF-beta信号调节的矛盾报告，这表明SMURF2确实具有抑制性作用，但通过单次泛素化而不是促进其降级来减弱SMAD3活性，但它可以减弱SMAD3的活性。由于两种蓝精灵的丧失都会导致胚胎致死性，因此我们创建了一个有条件的蓝精灵敲除等位基因，这使我们能够通过使用CRE重组酶的组织特异性表达在所需的组织中完全清除所有蓝精灵活性来研究蓝精灵的生理功能，并获得有条件的SMURF SMURF NULL细胞，并从后期或成人植物中获得有条件的SMURF Null belles embryos。我们对SMURF2敲除小鼠的研究还导致了先前未识别的SMURF2作为肿瘤抑制剂的意外发现，通常通过控制组蛋白修饰的表观遗传景观来维持基因组稳定性。我们发现SMURF2与调节DNA复制，染色质重塑和组蛋白修饰的一组蛋白质相互作用。我们目前正在使用体外和体内方法验证这些发现，并研究这些相互作用在基因组稳定性和肿瘤发生中的生物学相关性。与SMURF2的肿瘤抑制剂功能一致，我们发现细胞核中的Smurf2表达降低，但在乳腺癌细胞的细胞质中增加。 SMURF1表达在乳腺癌细胞的细胞质中也被上调。 Smurf1和Smurf2的过表达促进了裸小鼠模型中的转移，并诱导上皮到中性 - 肾小管转变，迁移和乳腺癌细胞的入侵，这表明蓝精灵在乳腺癌进展中起着重要作用。我们目前正在研究SMURF1和SMURF2作用的机制，促进乳腺癌细胞迁移和侵袭。