The Chaperone Protein Cct5 is Essential for Hematopoietic Stem Cell Maintenance.

Proper proteostasis is indispensable for the long-term maintenance of hematopoietic stem and progenitor cells (HSPCs). The TRiC/CCT (chaperonin-containing TCP-1) complex, a key constituent of cellular machinery facilitating accurate protein folding, has remained enigmatic in its specific function within HSPCs. Here we show that conditional knockout (KO) of Cct5 significantly impairs the maintenance of murine HSPCs. Primary and secondary transplantation experiments unequivocally demonstrate the incapacity of Cct5 KO HSPCs to reconstitute both myeloid and lymphoid lineage cells in recipient mice, highlighting the pivotal role of the TRiC/CCT complex in governing these cellular lineages. Furthermore, leveraging an integrated approach that merges a Protein-Protein Interaction (PPI) database with RNA sequencing (RNA-seq) data of HSPCs, our analysis reveals intricate interactions between Cct5 and vital transcription factors crucial for HSC homeostasis. Notably, Cct5 engages with MYC, PIAS1, TP53, ESR1, HOXA1, and JUN, intricately regulating the transcriptional landscape governing autophagy, myeloid differentiation, and cytoskeleton organization within HSPCs. Our study unveils the profound significance of TRiC/CCT complex-mediated proteostasis in orchestrating the maintenance and functionality of HSPCs.

Aspartyl-tRNA synthetase 2 orchestrates iron-sulfur metabolism in hematopoietic stem cells via fine-tuning alternative RNA splicing.

Aspartyl-tRNA synthetase 2 (Dars2) is involved in the regulation of mitochondrial protein synthesis and tissue-specific mitochondrial unfolded protein response (UPRmt). The role of Dars2 in the self-renewal and differentiation of hematopoietic stem cells (HSCs) is unknown. Here, we show that knockout (KO) of Dars2 significantly impairs the maintenance of hematopoietic stem and progenitor cells (HSPCs) without involving its tRNA synthetase activity. Dars2 KO results in significantly reduced expression of Srsf2/3/6 and impairs multiple events of mRNA alternative splicing (AS). Dars2 directly localizes to Srsf3-labeled spliceosomes in HSPCs and regulates the stability of Srsf3. Dars2-deficient HSPCs exhibit aberrant AS of mTOR and Slc22a17. Dars2 KO greatly suppresses the levels of labile ferrous iron and iron-sulfur cluster-containing proteins, which dampens mitochondrial metabolic activity and DNA damage repair pathways in HSPCs. Our study reveals that Dars2 plays a crucial role in the iron-sulfur metabolism and maintenance of HSPCs by modulating RNA splicing.

Ex Vivo Expansion and Homing of Human Cord Blood Hematopoietic Stem Cells.

Cord blood (CB) has been proven to be an alternative source of haematopoietic stem cells (HSCs) for clinical transplantation and has multiple advantages, including but not limited to greater HLA compatibility, lower incidence of graft-versus-host disease (GvHD), higher survival rates and lower relapse rates among patients with minimal residual disease. However, the limited number of HSCs in a single CB unit limits the wider use of CB in clinical treatment. Many efforts have been made to enhance the efficacy of CB HSC transplantation, particularly by ex vivo expansion or enhancing the homing efficiency of HSCs. In this chapter, we will document the major advances regarding human HSC ex vivo expansion and homing and will also discuss the possibility of clinical translation of such laboratory work.

ADGRG1 enriches for functional human hematopoietic stem cells following ex vivo expansion-induced mitochondrial oxidative stress.

The heterogeneity of human hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs) under stress conditions such as ex vivo expansion is poorly understood. Here, we report that the frequencies of SCID-repopulating cells were greatly decreased in cord blood (CB) CD34+ HSCs and HPCs upon ex vivo culturing. Transcriptomic analysis and metabolic profiling demonstrated that mitochondrial oxidative stress of human CB HSCs and HPCs notably increased, along with loss of stemness. Limiting dilution analysis revealed that functional human HSCs were enriched in cell populations with low levels of mitochondrial ROS (mitoROS) during ex vivo culturing. Using single-cell RNA-Seq analysis of the mitoROS low cell population, we demonstrated that functional HSCs were substantially enriched in the adhesion GPCR G1-positive (ADGRG1+) population of CD34+CD133+ CB cells upon ex vivo expansion stress. Gene set enrichment analysis revealed that HSC signature genes including MSI2 and MLLT3 were enriched in CD34+CD133+ADGRG1+ CB HSCs. Our study reveals that ADGRG1 enriches for functional human HSCs under oxidative stress during ex vivo culturing, which can be a reliable target for drug screening of agonists of HSC expansion.

Effect of silicone oil heat treatment on the chemical composition, cellulose crystalline structure and contact angle of Chinese parasol wood.

The effect of silicone oil heat treatment (SOTH) on the chemical composition, cellulose crystalline structure, thermal degradation and contact angle of Chinese parasol wood were examined in this study. Samples were heated at 150°C, 180°C and 210°C for 2h and 8h, after SOHT chemical composition, fourier transformed infrared (FTIR), thermogravimetric analysis (TGA) and X-ray diffraction (XRD) of the treated samples were evaluated. Results showed that the chemical components of the wood were affected after SOHT particularly when treated at 210°C for 8h. Changes in the chemical components was due to the degradation of biopolymer components of the wood during SOHT. The crystallinity index of cellulose and contact angle of the SOHT samples was increased. The findings demonstrate the potential of SOHT for modification of wood. Thus an economical and eco-friendly approach to thermally modified wood was achieved in this study.

Dexmedetomidine attenuates hypoxemia during palliative reconstruction of the right ventricular outflow tract in pediatric patients.

The objective of this study was to investigate whether the α agonist dexmedetomidine has the ability to attenuate hypoxemia in pediatric patients undergoing palliative pulmonary artery reconstruction.From January 2009 to January 2013, a total of 25 pediatric patients with Tetralogy of Fallot, pulmonary atresia (ventricular septal defect), or persistent truncus arteriosus (I) were enrolled in our study. Due to hypoplastic pulmonary arteries, all patients received palliative pulmonary artery reconstruction. During the perioperative period, they were allocated to receive either dexmedetomidine (bolus dose of 0.3 µg/kg followed by an infusion of 0.2-0.3 µg/kg/h, n = 15) or control drug (n = 10) intravenously. Any desaturation was recorded. Heart rate, mean arterial pressure, pulse oximetry, and arterial blood gas parameters were measured during the perioperative period.There were no significant differences between the groups in hemodynamic variables. The arterial oxygen saturation and arterial blood gas parameters increased in the dexmedetomidine groups (P < 0.05).These findings suggest that the injection of dexmedetomidine can attenuate hypoxemia during palliative pulmonary artery reconstruction in pediatric patients.

No association of functional variant in pri-miR-218 and risk of congenital heart disease in a Chinese population.

BACKGROUND: MiR-218 plays an important role in heart development in zebrafish. pri-miR-218 rs11134527 variant is associated with cervical cancer carcinogenesis. Therefore, we hypothesized that single nucleotide polymorphism (SNPs) in pri-miR-218 might influence susceptibility to sporadic congenital heart disease (CHD). METHODS AND RESULTS: We conducted a case-control study of CHD in a Chinese population to test our hypothesis by sequencing and genotyping pri-miR-218 in 1116 CHD cases and 1219 non-CHD controls. We identified one SNP rs11134527 located in pri-miR-218 sequence. Logistic regression analyses showed that there was no significant association in genotype and allele frequencies of pri-miR-218 rs11134527 A/G polymorphism between CHD cases in overall or various subtypes and the control group. However, real-time PCR analysis showed that rs11134527 allele G significantly increased mature miR-218 expression. In vitro binding assays further revealed that the rs11134527 variant affects miR-218-mediated regulation of Robo1. CONCLUSIONS: This is the first study to investigate the relationship between miR-218 and CHD cases. Our results demonstrate that the functional variant rs11134527 in pri-miR-218 has no major role in genetic susceptibility to sporadic CHD, at least in the population studied here.