The Role of Hsf1 in Hematopoietic Stem Cell Aging

Hsf1在造血干细胞衰老中的作用

• 批准号: 10749675
• 负责人: Fanny Jiahua Zhou
• 金额: $ 4万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10749675
• 关键词: Age; Aging; Anemia; Binding; Binding Sites; Biogenesis; Biological Assay; Blood; Blood Cells; Blood Coagulation Disorders; Bone marrow failure; Cell Nucleus; Cell Survival; Cells; Cellular Stress; ChIP-seq; Cytoplasm; DNA Sequence Alteration; Data; Elderly; Elements; Exhibits; Fellowship; Gene Expression; Genes; Genetic Complementation Test; Genetic Transcription; Health; Heat Losses; Heat shock proteins; Heat-Shock Response; Hematologic Neoplasms; Hematopoiesis; Hematopoietic; Hematopoietic System; Hematopoietic stem cells; Human; Immune; Immunity; Impairment; Incidence; Inflammation; Knockout Mice; Laboratory Finding; Life; Lymphoid; Molecular Chaperones; Mus; Myelogenous; Older Population; Outcome Study; Oxidative Stress; Pathway interactions; Process; Protein Biosynthesis; Protein Disulfide Isomerase; Proteins; Proteome; Regenerative capacity; Regulation; Role; Stress; Testing; Transplantation; Up-Regulation; activation-induced cytidine deaminase; adaptive immunity; age related; aged; experience; fitness; heat shock transcription factor; heat-shock factor 1; hematopoietic stem cell aging; hematopoietic stem cell self-renewal; immune function; improved; insight; middle age; misfolded protein; multicatalytic endopeptidase complex; new therapeutic target; preservation; prevent; progenitor; programs; promoter; protein aggregation; protein folding; proteostasis; proteotoxicity; reconstitution; regeneration function; regenerative cell; response; self-renewal; single-cell RNA sequencing; stem cell aging; stem cell function; therapeutic target; trafficking; transcription factor; transcriptome sequencing; transglutaminase 2; young adult

PROJECT SUMMARY Hematopoietic stem cells (HSCs) regenerate all blood and immune cells throughout life. Aging HSCs exhibit diminished regenerative function, reduced lymphoid potential, and clonal outgrowth that is associated with compromised immunity as well as an increased incidence of anemia, bone marrow failure, and hematological malignancies in older adults. The regulation of protein homeostasis (proteostasis) has recently emerged as a fundamental process required to promote HSC self-renewal. Loss of proteostasis is considered one of the hallmarks of aging, but to what extent it contributes to stem cell aging is largely unknown. An essential pathway in maintaining proteostasis is the Heat Shock Response, which is regulated by the master transcription factor Heat shock factor 1 (Hsf1). Hsf1 induces expression of heat shock proteins that aid in proper protein folding, trafficking, and degradation. At steady state, Hsf1 is typically sequestered in the cytoplasm, but translocates into the nucleus in response to cellular and proteotoxic stress. Previously, we demonstrated that HSCs undergo cellular stress when cultured ex vivo and Hsf1 activation can alleviate this stress to maintain HSC regenerative activity. Hsf1 is highly expressed in young and old adult HSCs but is specifically activated during aging in middle- aged and old adult HSCs. Aging is a notably stressful process associated with the accumulation of genetic mutations, inflammation, and oxidative stress. Based on these preliminary results, the central hypothesis of this proposal is that Hsf1 activation promotes HSC function and proteostasis during aging. To test this hypothesis, Aim 1 will examine the role of Hsf1 in aging HSC function and proteostasis using conditional Hsf1 knockout mice. HSC function will be assessed in competitive transplantation assays and proteostasis will be assessed by quantifying protein synthesis, proteasome activity, misfolded protein, unfolded protein, and protein aggregate abundance. I expect that there will be less reconstitution in aged Hsf1-deficient HSCs and more protein synthesis, misfolded and unfolded proteins, and aggregates. While Hsf1 activation is hypothesized to be important for HSC function during aging, the mechanism underlying heterochronic Hsf1 activation is unknown. Preliminary RNA-sequencing results revealed that Transglutaminase 2 (Tgm2), involved in Hsf1 activation, is significantly upregulated in old adult HSCs. Thus, Aim 2 will examine if age-related Hsf1 activation depends on Tgm2 upregulation. Hsf1 activation, HSC function, and proteostasis will be assessed in conditional Tgm2 knockout mice. I expect that loss of Tgm2 in aging HSCs will disrupt proteostasis and exhibit an associated decline in fitness and function due to a decrease in Hsf1 activation. Collectively, these studies will provide deeper insights into mechanisms that regulate proteostasis during stem cell aging. These findings will uncover new therapeutic targets to promote HSC fitness during aging.

项目摘要 造血干细胞（HSC）在整个生命过程中再生所有血液和免疫细胞。老化HSC表现出 再生功能减弱，淋巴潜能降低，克隆生长与 免疫力受损以及贫血、骨髓衰竭和血液学异常的发生率增加。 老年人的恶性肿瘤蛋白质稳态（proteostasis）的调节最近已经成为一种新的研究领域。 促进HSC自我更新所需的基本过程。蛋白质稳态的丧失被认为是 它是衰老的标志，但在多大程度上有助于干细胞衰老在很大程度上是未知的。一个重要的途径 维持蛋白质稳态的是热休克反应，它由主转录因子调节 热休克因子1（Hsf1）。Hsf1诱导热休克蛋白的表达，帮助正确的蛋白质折叠， 贩运和退化。在稳定状态下，Hsf1通常被隔离在细胞质中，但易位到细胞质中。 细胞核对细胞和蛋白毒性应激的反应。以前，我们证明了HSC经历 体外培养时细胞应激和Hsf1的激活可以缓解这种应激，维持HSC的再生 活动Hsf1在年轻和年老的成体HSC中高度表达，但在中年HSC中在衰老过程中特异性激活。 老年和老年成体HSC。衰老是一个与遗传物质积累相关的显着压力过程 突变、炎症和氧化应激。根据这些初步结果，本研究的中心假设 推测Hsf1激活促进衰老过程中HSC功能和蛋白质稳态。为了验证这个假设， 目的1利用条件性Hsf1基因敲除小鼠研究Hsf1在衰老HSC功能和蛋白稳态中的作用。 将在竞争性移植测定中评估HSC功能，并将通过以下方法评估蛋白质稳态： 定量蛋白质合成、蛋白酶体活性、错误折叠蛋白质、未折叠蛋白质和蛋白质聚集体 丰饶。我预计，在年老的Hsf1缺陷的HSC中， 合成、错误折叠和未折叠蛋白质以及聚集体。虽然Hsf1激活被假设为 尽管Hsf1在衰老过程中对HSC功能很重要，但异时Hsf1激活的机制尚不清楚。 初步的RNA测序结果显示，与Hsf1激活有关的转氨酶2（Tgm2）， 在年老的成体HSC中显著上调。因此，目标2将检查与年龄相关的Hsf1激活是否依赖于 Tgm2上调。将在条件性Tgm 2中评估Hsf1活化、HSC功能和蛋白质稳态。 敲除小鼠我预期老化HSC中Tgm2的缺失将破坏蛋白质稳态，并表现出相关的 由于Hsf1激活减少，健康和功能下降。总的来说，这些研究将提供更深入的 对干细胞衰老过程中蛋白质稳态调节机制的深入了解。这些发现将揭示新的 治疗目标，以促进衰老过程中HSC的适应性。