Xuepeng Wang, Baskar Ramdas, Ramesh Kumar, Ji Zhang, Reuben Kapur
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引用次数: 0
Abstract
Ex vivo expansion of hematopoietic stem cells (HSCs) is limited by mitochondrial stress-induced loss of stemness. To identify protective mechanisms resembling the hypoxic bone marrow niche, we performed single-cell transcriptomics on hypoxia-collected HSCs, revealing significant downregulation of Rho-associated kinase 1 (ROCK1). This observation suggested ROCK1 as a potential regulator of HSC homeostasis. We tested this by genetically or pharmacologically inhibiting ROCK1 with shRNA or Y27632, which reduced mitochondrial reactive oxygen species, mitochondrial mass, and membrane potential while promoting expansion of phenotypic HSCs (Lin⁻CD34⁺CD38⁻CD45RA⁻CD49f⁺CD90⁺). Mechanistically, ROCK1 inhibition attenuated DRP1-mediated mitochondrial fission by decreasing p-DRP1(Ser616) and increasing p-DRP1(Ser637), thereby reducing mitochondrial fragmentation. Additionally, ROCK1 inhibition elevated BCL2 expression and reduced active Caspase-3 levels, indicating suppressed apoptosis. Limiting dilution transplants demonstrated a fourfold increase in functional HSC frequency following ROCK1 inhibition, with enhanced long-term engraftment in secondary recipients. Our findings identify ROCK1 as a critical regulator of mitochondrial dynamics in HSCs and provide a mechanistic basis for targeting ROCK1 to enhance functional HSC expansion, offering a promising strategy to improve outcomes in HSC transplantation by mimicking hypoxic niche signals ex vivo.
期刊介绍:
Title: Leukemia
Journal Overview:
Publishes high-quality, peer-reviewed research
Covers all aspects of research and treatment of leukemia and allied diseases
Includes studies of normal hemopoiesis due to comparative relevance
Topics of Interest:
Oncogenes
Growth factors
Stem cells
Leukemia genomics
Cell cycle
Signal transduction
Molecular targets for therapy
And more
Content Types:
Original research articles
Reviews
Letters
Correspondence
Comments elaborating on significant advances and covering topical issues