Homeostasis of the ER in Differentiating B-cells

B 细胞分化过程中 ER 的稳态

• 批准号: 7987892
• 负责人: JOSEPH W BREWER
• 金额: $ 31.92万
• 依托单位: UNIVERSITY OF SOUTH ALABAMA
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-06-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7987892
• 关键词: Address; Affect; Affinity; Anabolism; Antibodies; Antibody Formation; Antigens; Autoimmune Diseases; B-Lymphocytes; Biochemical; Biogenesis; Cell Culture System; Cell Line; Cell physiology; Cellular Membrane; Cues; Cytidine Diphosphate Choline; Disease; Drug Design; Endoplasmic Reticulum; Enzymes; Equilibrium; Fibroblasts; Frequencies; Genes; Goals; Haptens; Homeostasis; Immunoglobulin Class Switching; Immunoglobulin M; Immunoglobulin-Secreting Cells; In Vitro; Infection; Investigation; Knock-out; Knockout Mice; Lead; Lecithin; Life; Light; Link; Lipids; Liver; Lupus; Malignant Neoplasms; Measures; Mediating; Membrane; Memory B-Lymphocyte; Messenger RNA; Metabolic; Molecular; Molecular Chaperones; Morphology; Multiple Myeloma; Mus; Organelles; Pancreas; Pathway interactions; Pharmaceutical Preparations; Phospholipids; Post-Transcriptional Regulation; Process; Production; Proliferating; Protein Isoforms; Proteins; RNA Splicing; Reaction; Regulation; Research; Rough endoplasmic reticulum; Signal Pathway; Signal Transduction; Staging; Structure of germinal center of lymph node; System; Techniques; Work; differentiated B cell; fighting; in vivo; inhibitor/antagonist; lipid metabolism; mouse model; novel; programs; protein transport; public health relevance; research study; response; transcription factor; tumor progression

DESCRIPTION (provided by applicant): The long-term goal of this research program is to delineate mechanisms that regulate homeostasis of the endoplasmic reticulum (ER) in B-lymphocytes and to understand how these same mechanisms influence the fate of activated B-cells. A link exists between the supply of phosphatidylcholine (PtdCho), the most abundant phospholipid in cellular membranes, and unfolded protein response (UPR) signaling pathway. XBP1(S), a transcription factor generated by the UPR, is required for normal antibody production, maximal increases in total PtdCho and ER expansion in stimulated B-cells. Another UPR transcription factor, ATF61, also has the ability to induce PtdCho synthesis and ER expansion. Deletion of CCT1, the rate-limiting enzyme in PtdCho synthesis, markedly diminishes PtdCho production in activated B-cells. This correlates with accelerated induction of XBP1(S) and IgM secretion, but little production of other antibody isotypes. Therefore, we hypothesize that PtdCho supply can influence the fate of activated B-cells by interfacing with the UPR to promote PtdCho synthesis and drive differentiation of antibody-secreting B-cells. The project will focus on four specific aims and utilize gene knockout mouse models, cell culture systems and a combination of molecular, biochemical and cellular techniques. In aim 1, experiments will address the mechanism by which XBP1(S) up-regulates PtdCho supply in activated B-cells. In aim 2, studies will assess the contributions of ATF61 to the regulation of PtdCho synthesis and ER expansion in activated B-cells. In aim 3, experiments will address how a limited PtdCho supply at distinct stages of the B-cell response affects B-cell function and fate in vivo. In aim 4, the mechanism linking PtdCho supply to UPR activation will be explored. Experiments will assess how reduced levels of PtdCho affect ER function and protein transport in the secretory pathway. Antibody-mediated autoimmune disorders such as lupus and B-cell cancers like multiple myeloma are devastating diseases, underscoring the need to identify novel regulatory mechanisms in B-cells that might provide new targets for drug design. The UPR is also involved in many other physiologically significant processes including tumor progression and proper function of the pancreas and liver. Understanding how the UPR works in normal cellular processes is necessary for rational exploration of drugs to modulate this pathway in disease states. PUBLIC HEALTH RELEVANCE: Normal B-cells in the body help fight infection, but B-cells that malfunction can cause life- threatening diseases like cancer. In this research, processes that control B-cell function are being studied. The results may lead to new treatments for diseases caused by faulty B-cells.

描述（由申请人提供）：本研究计划的长期目标是描述调节B淋巴细胞内质网（ER）稳态的机制，并了解这些机制如何影响活化B细胞的命运。磷脂酰胆碱（PtdCho）是细胞膜中最丰富的磷脂，其供应与未折叠蛋白反应（UPR）信号通路之间存在联系。由UPR产生的转录因子XBP1（S）是正常抗体产生所需的，在刺激的B细胞中总PtdCho和ER扩增的最大增加。另一种UPR转录因子ATF61也具有诱导PtdCho合成和ER扩增的能力。缺失PtdCho合成中的限速酶CCT 1显著减少活化B细胞中的PtdCho产生。这与XBP1（S）和IgM分泌的加速诱导相关，但几乎不产生其他抗体同种型。因此，我们假设PtdCho供应可以通过与UPR相互作用以促进PtdCho合成并驱动抗体分泌B细胞的分化来影响活化B细胞的命运。该项目将侧重于四个具体目标，并利用基因敲除小鼠模型，细胞培养系统和分子，生物化学和细胞技术的组合。在目标1中，实验将解决XBP1（S）在活化的B细胞中上调PtdCho供应的机制。在目标2中，研究将评估ATF 61对活化B细胞中PtdCho合成和ER扩增的调节的贡献。在目标3中，实验将解决在B细胞应答的不同阶段有限的PtdCho供应如何影响体内B细胞功能和命运。在目标4中，将探索将PtdCho供应与UPR激活联系起来的机制。实验将评估PtdCho水平降低如何影响ER功能和分泌途径中的蛋白质转运。抗体介导的自身免疫性疾病，如狼疮和B细胞癌，如多发性骨髓瘤，是毁灭性的疾病，强调需要确定新的调节机制，在B细胞，可能提供新的药物设计的目标。UPR还参与许多其他生理学上重要的过程，包括肿瘤进展和胰腺和肝脏的正常功能。了解UPR如何在正常细胞过程中发挥作用，对于合理探索药物在疾病状态下调节这一途径是必要的。 公共卫生关系：体内正常的B细胞有助于抵抗感染，但B细胞发生故障可能导致危及生命的疾病，如癌症。在这项研究中，正在研究控制B细胞功能的过程。这些结果可能会导致由缺陷B细胞引起的疾病的新疗法。