摘要: Despite the regenerative and self-repair capabilities of bone tissues, significant bone loss can result in substantial bone defects. This study was aimed at investigating the role and underlying mechanisms of the mechanosensitive protein PDZ and LIM Domain 5 (PDLIM5) in the osteogenic differentiation of human adipose-derived stem cells (hASCs) under cyclic tensile stress conditions relevant to bone tissue repair. Utilising proteomics and single-cell RNA sequencing, we identified PDLIM5 and serpin E2 as key genes associated with the osteogenic differentiation of stem cells. To evaluate the expression levels of these genes and related proteins, we utilised western blotting, immunofluorescence and alkaline phosphatase (ALP) staining. Furthermore, lentiviral transfection, Cell Counting Kit-8 (CCK-8) assays, transwell migration assays, wound healing assays and protein-protein interaction analyses were conducted to evaluate changes in osteogenic differentiation under both chemical and physical stimuli, as well as to explore the relationship between serine protease inhibitor E2 (serpin E2) and its downstream effector, PDLIM5. The interactions among serpin E2, integrin beta 3 and PDLIM5 were confirmed through Haematoxylin and Eosin (H&E) staining, immunohistochemistry and immunofluorescence staining of bone tissues and primary adipose-derived stem cells isolated from integrin beta 3 knockout mice. Our findings indicate that PDLIM5 modulates the osteogenic differentiation of hASCs via a signalling pathway involving serpin E2, integrin beta 3 and lamin A.

摘要: The E3 ubiquitin ligase RNF187, also known as RING domain AP1 coactivator-1, is a member of the RING finger family. RNF187 is indispensable for the proliferation and migration of GC-1 cells derived from mouse spermatogonia and GC-2 cells derived from spermatocytes. However, it remains unclear whether RNF187 plays a crucial role in the self-renewal and migration of human spermatogonial stem cells (SSCs). In this study, we observed a positive correlation between RNF187 expression and the proliferation and migration of human SSCs. Through co-immunoprecipitation and mass spectrometry analyses, we identified WD repeat-containing protein 77 (WDR77) as an interacting partner of RNF187. Specifically, RNF187 recognises the K118 site of WDR77 through lysine 48-linked polyubiquitination, subsequently mediating its degradation via the ubiquitin-proteasome system (UPS). Further studies have revealed that decreased expression of WDR77 diminishes the symmetric dimethylation at H4R3 (H4R3me2s) catalysed by its interacting protein, the arginine methyltransferase PRMT5. This, in turn, relieves the transcriptional repression of early growth response protein 1 (EGR1), a positive regulator for human SSC maintenance. In conclusion, this study has unveiled a pivotal role for RNF187 in the proliferation and migration of human SSCs. This may provide a promising strategy for addressing non-obstructive azoospermia (NOA) caused by SSC dysfunction.

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摘要: Human induced pluripotent stem cells (hiPSCs) represent a promising cell source for generating functional cells suitable for clinical therapeutic applications, particularly in the context of autologous cell therapies. However, the production of hiPSCs through genetic manipulation, especially involving oncogenes, may raise safety concerns. Furthermore, the complexity and high costs associated with hiPSCs generation have hindered their broad clinical use. In this study, we utilised a recently developed chemical reprogramming method in conjunction with a guided differentiation protocol, introducing a chemically defined strategy for generating functional human retinal pigment epithelium (RPE) cells from adipose tissue, bypassing conventional hiPSCs generation challenges. By utilising small molecule-based chemical cocktails, we reprogrammed somatic adipose cells into human chemically induced pluripotent stem cells (hCiPSCs) in a safer and more streamlined manner, entirely free from gene manipulation. Subsequent differentiation of hCiPSCs into functional RPE cells demonstrated their capability for secretion and phagocytosis, emphasising their vital role in maintaining retinal homeostasis and underscoring their therapeutic potential. Our findings highlight the transformative potential of hCiPSCs as a safer, more efficient option for personalised cell therapies, with applications extending beyond ocular disease to a wide range of medical conditions.

摘要: Lactate has been widely recognised as an energy source and metabolic by-product, but increasing evidence supports its critical role as a signalling molecule or epigenetic substrate. During early embryogenesis, lactate production increases during the transition from early to late blastocyst, coinciding with the differentiation of inner mass cell (ICM) into epiblast (EPI) and primitive endoderm (PrE), termed the second cell fate decision. However, the role of this hallmark metabolic change in the second cell fate segregation remains unknown. Herein, using in vitro and in vivo models, we found lactate production is preferentially increased in PrE cells and is essential for ICM differentiation into PrE. Mechanically, increased lactate in PrE precursor cells and FGF signalling in EPI precursor cells reciprocally activate each other and synergise to prompt PrE specification, forming an intercellular positive feedback loop essential for this lineage commitment. Additionally, lactate enhanced histone lactylation levels during differentiation into PrE fate. Thus, our findings construct a complex multilayer model in which intracellular metabolite in PrE cooperates with intercellular growth factor signalling from EPI to regulate early embryonic lineage commitment. Highlighting the multifaceted lactate's function, our findings also advance the current knowledge that bridges epigenetic reprogramming and metabolic remodelling during early embryonic development.