Selenoprotein-Mediated Redox Regulation Shapes the Cell Fate of HSCs and Mature lineages [bulkRNA-seq]
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ABSTRACT: The maintenance of cellular redox balance is crucial for cell survival and homeostasis and is disrupted with aging. Selenoproteins, comprising essential antioxidant enzymes, raise intriguing questions about their involvement in hematopoietic aging and potential reversibility. First, we observed a notable mRNA downregulation of key antioxidant selenoproteins in aged human hematopoietic stem cells (HSCs). Therefore, we employed tRNAsec gene (Trsp) knockout (KO) mouse model to simulate disrupted selenoprotein synthesis, revealing the insights into the protective roles of selenoproteins in preserving HSC stemness and facilitating B cell maturation, despite negligible effects on myeloid cells. Notably, Trsp KO exhibited B lymphocytopenia and reduced HSCs’ self-renewal capacity, reminiscent of aged phenotypes, along with the upregulation of aging-related genes in both HSCs and Pre-B cells. While Trsp KO activated an antioxidant response transcription factor NRF2 across all hematopoietic cells, we delineated a lineage-dependent phenotype driven by lipid peroxidation, which was exacerbated with aging yet ameliorated by ferroptosis inhibitors such as vitamin E. Interestingly, the myeloid genes were ectopically expressed in Pre-B cells of Trsp KO mice and the KO Pre-B/Pro-B cells displayed differentiation toward CD11b+ fraction in the transplant model, suggesting that disrupted selenoprotein synthesis induces the potential of B to myeloid switch. Collectively, our findings underscore the critical role of selenoprotein-mediated redox regulation in maintaining balanced hematopoiesis and highlight the preventive potential of selenoproteins against aging-related hematopoietic alterations.
Project description:The maintenance of cellular redox balance is crucial for cell survival and homeostasis and is disrupted with aging. Selenoproteins, comprising essential antioxidant enzymes, raise intriguing questions about their involvement in hematopoietic aging and potential reversibility. First, we observed a notable mRNA downregulation of key antioxidant selenoproteins in aged human hematopoietic stem cells (HSCs). Therefore, we employed tRNAsec gene (Trsp) knockout (KO) mouse model to simulate disrupted selenoprotein synthesis, revealing the insights into the protective roles of selenoproteins in preserving HSC stemness and facilitating B cell maturation, despite negligible effects on myeloid cells. Notably, Trsp KO exhibited B lymphocytopenia and reduced HSCs’ self-renewal capacity, reminiscent of aged phenotypes, along with the upregulation of aging-related genes in both HSCs and Pre-B cells. While Trsp KO activated an antioxidant response transcription factor NRF2 across all hematopoietic cells, we delineated a lineage-dependent phenotype driven by lipid peroxidation, which was exacerbated with aging yet ameliorated by ferroptosis inhibitors such as vitamin E. Interestingly, the myeloid genes were ectopically expressed in Pre-B cells of Trsp KO mice and the KO Pre-B/Pro-B cells displayed differentiation toward CD11b+ fraction in the transplant model, suggesting that disrupted selenoprotein synthesis induces the potential of B to myeloid switch. Collectively, our findings underscore the critical role of selenoprotein-mediated redox regulation in maintaining balanced hematopoiesis and highlight the preventive potential of selenoproteins against aging-related hematopoietic alterations.
Project description:Comparative analysis of gene expression in the liver of the Trsp-knockout mice (Trspfl/fl-AlbCre+/+) and A34 (Trspfl/fl-AlbCre+/+-A34t/t), G37L (Trspfl/fl-AlbCre+/+-G37t/t; 2 copies), G37H (Trspfl/fl-AlbCre+/+-G37t/t; 16 copies) transgenic mice with gene expression of wild type mice (Trsp+/+-AlbCre+/+). Sec (selenocysteine) is biosynthesized on its tRNA and incorporated into selenium-containing proteins (selenoproteins) as the 21st amino acid residue. Selenoprotein synthesis is dependent on Sec tRNA and the expression of this class of proteins can be modulated by altering Sec tRNA expression. The gene encoding Sec tRNA (Trsp) is a single-copy gene and its targeted removal in liver demonstrated that selenoproteins are essential for proper function wherein their absence leads to necrosis and hepatocellular degeneration. In the present study, we found that the complete loss of selenoproteins in liver was compensated for by an enhanced expression of several phase II response genes and their corresponding gene products. The replacement of selenoprotein synthesis in mice carrying mutant Trsp transgenes, wherein housekeeping, but not stress-related selenoproteins are expressed, led to normal expression of phase II response genes. Thus the present study provides evidence for a functional link between housekeeping selenoproteins and phase II enzymes. Trsp vs DTrsp; Trsp vs A34; Trsp vs G37L; Trsp vs G37H. Biological replicates from littermates. One replicate per array.
Project description:Comparative analysis of gene expression in the liver of the Trsp-knockout mice (Trspfl/fl-AlbCre+/+) and A34 (Trspfl/fl-AlbCre+/+-A34t/t), G37L (Trspfl/fl-AlbCre+/+-G37t/t; 2 copies), G37H (Trspfl/fl-AlbCre+/+-G37t/t; 16 copies) transgenic mice with gene expression of wild type mice (Trsp+/+-AlbCre+/+). Sec (selenocysteine) is biosynthesized on its tRNA and incorporated into selenium-containing proteins (selenoproteins) as the 21st amino acid residue. Selenoprotein synthesis is dependent on Sec tRNA and the expression of this class of proteins can be modulated by altering Sec tRNA expression. The gene encoding Sec tRNA (Trsp) is a single-copy gene and its targeted removal in liver demonstrated that selenoproteins are essential for proper function wherein their absence leads to necrosis and hepatocellular degeneration. In the present study, we found that the complete loss of selenoproteins in liver was compensated for by an enhanced expression of several phase II response genes and their corresponding gene products. The replacement of selenoprotein synthesis in mice carrying mutant Trsp transgenes, wherein housekeeping, but not stress-related selenoproteins are expressed, led to normal expression of phase II response genes. Thus the present study provides evidence for a functional link between housekeeping selenoproteins and phase II enzymes.
Project description:Comparative analysis of gene expression in bone marrow-derived macrophages (BMDM) from trsp knockout mice (Trspfl/fl-LysM-Cre+/-) and Control (Trspfl/fl-LysM-Cre-/-) mice. Selenium, a micronutrient whose deficiency in the diet causes immune dysfunction and inflammatory disorders, exerts its physiological effects partly in the form of selenium-containing proteins (selenoproteins). Incorporation of selenium into the amino acid selenocysteine (Sec), and subsequently into selenoproteins, is mediated by Sec tRNA[Ser]Sec. To identify macrophage-specific selenoprotein function, we generated mice with the Sec tRNA[Ser]Sec gene specifically deleted in myeloid cells. These mutant mice were devoid of the selenoproteome in macrophages, yet exhibited largely normal inflammatory responses. However, selenoprotein deficiency led to aberrant expression of extracellular matrix-related genes, and diminished migration of macrophages in a protein gel matrix. Therefore, selenium status may affect immune defense and tissue homeostasis through its effect on selenoprotein expression and the trafficking of tissue macrophages. We have generated mice in which we have selectively removed the selenocysteine tRNA gene (trsp) in macrophages under the control of LysM-Cre promoter. Microarray analysis was performed on RNA samples taken from bone marrow-derived macrophages in knockout and control mice. 1. Control unstimulated 2. Knockout unstimulated 3. Control lipopolysaccharide (LPS) stimulated (4h) 4. Knockout LPS stimulated (4h). Three replicates for each condition. Thus, a total of 12 samples.
Project description:Comparative analysis of gene expression in bone marrow-derived macrophages (BMDM) from trsp knockout mice (Trspfl/fl-LysM-Cre+/-) and Control (Trspfl/fl-LysM-Cre-/-) mice. Selenium, a micronutrient whose deficiency in the diet causes immune dysfunction and inflammatory disorders, exerts its physiological effects partly in the form of selenium-containing proteins (selenoproteins). Incorporation of selenium into the amino acid selenocysteine (Sec), and subsequently into selenoproteins, is mediated by Sec tRNA[Ser]Sec. To identify macrophage-specific selenoprotein function, we generated mice with the Sec tRNA[Ser]Sec gene specifically deleted in myeloid cells. These mutant mice were devoid of the selenoproteome in macrophages, yet exhibited largely normal inflammatory responses. However, selenoprotein deficiency led to aberrant expression of extracellular matrix-related genes, and diminished migration of macrophages in a protein gel matrix. Therefore, selenium status may affect immune defense and tissue homeostasis through its effect on selenoprotein expression and the trafficking of tissue macrophages.
Project description:MTD project_description Inflammation and decreased stem cell function characterize organism aging, yet the relationship between these factors remains incompletely understood. This study shows that aged hematopoietic stem and progenitor cells exhibit increased ground-stage NF-κB activity, which enhances their responsiveness to undergo differentiation and loss of self-renewal in response to inflammation. The study identifies Rad21/cohesin as a critical mediator of NF-κB signals, by increasing chromatin accessibility of inter-/intra-genic and enhancer regions. Rad21/NF-κB are required for normal differentiation, but limit self-renewal of hematopoietic stem cells (HSCs) during aging and inflammation in an NF-κB dependent manner. HSCs from aged mice fail to downregulate Rad21/cohesin and inflammation/differentiation inducing signals in the resolution phase after acute inflammation. and The inhibition of cohesin/NF-κB is sufficient to revert the hypersensitivity of aged HSPCs to inflammation-induced differentiation. During aging, myeloid-biased HSCs with disrupted and naturally occurring reduced expression of Rad21/cohesin are increasingly selected over lymphoid-biased HSCs. Together, Rad21/cohesin mediated NF-κB signaling limits HSPC function during aging and selects for cohesin deficient HSCs with myeloid skewed differentiation.
Project description:Increasing evidence links metabolic activity and cell growth to decline in hematopoietic stem cell (HSC) function during aging. The Lin28b/Hmga2 pathway controls tissue development and in the hematopoietic system the postnatal downregulation of this pathway causes a decrease in self renewal of adult HSCs compared to fetal HSCs. Igf2bp2 is an RNA binding protein and a mediator of the Lin28b/Hmga2 pathway, which regulates metabolism and growth signaling by influencing RNA stability and translation of its target genes. It is currently unknown whether Lin28/Hmga2/Igf2bp2 signaling impacts on aging-associated impairments in HSC function and hematopoiesis. Here, we analyzed homozygous Igf2bp2 germline knockout mice and wildtype control animals to address this question. The study shows that Igf2bp2 deletion rescues aging phenotypes of the hematopoietic system, such as the expansion of HSC numbers in bone marrow and the biased increase of myeloid cells in peripheral blood. This rescue of hematopoietic aging coincides with reduced mitochondrial metabolism and glycolysis in Igf2bp2-/- HSCs compared to Igf2bp2+/+ HSCs. Conversely, Igf2bp2 overexpression activates protein synthesis pathways in HSCs and leads to a rapid loss of self renewal by enhancing myeloid skewed differentiation in an mTOR/PI3K-dependent manner. Together, these results show that Igf2bp2 regulates energy metabolism and growth signaling in HSCs and that the activity of this pathways influences self renewal, differentiation, and aging of HSCs.
Project description:Asrij deletion in mice causes loss of HSC quiescence, myeloid skewing, reduced p53 and increased DNA damage, features attributed to aged hematopoietic stem cells (HSCs). To identify the pathways and processes driving the observed HSC aging-like phenotypes upon asrij depletion and to compare the asrij KO transcriptome with aged wild type HSCs, we performed RNA-seq gene expression profiling of Lin- Sca-1+ c-Kit+ CD150+ CD48- stem cells isolated from asrij KO or asrij floxed (control) mouse bone marrow. Our results identify Asrij as a potential driver of aging-like alterations in HSCs and the RNA-seq based transcriptome could help identify additional aging biomarkers and develop strategies to rejuvenate aged HSCs or prevent premature HSC aging.
Project description:Loss of immune function and an increased incidence of myeloid leukemia are two of the most clinically significant consequences of aging of the hematopoietic system. To better understand the mechanisms underlying hematopoietic aging, we evaluated the cell intrinsic functional and molecular properties of highly purified long-term hematopoietic stem cells (LT-HSCs) from young and old mice. We found that LT-HSC aging was accompanied by cell autonomous changes, including increased stem cell self-renewal, differential capacity to generate committed myeloid and lymphoid progenitors, and diminished lymphoid potential. Expression profiling revealed that LT-HSC aging was accompanied by the systemic down-regulation of genes mediating lymphoid specification and function and up-regulation of genes involved in specifying myeloid fate and function. Moreover, LT-HSCs from old mice expressed elevated levels of many genes involved in leukemic transformation. These data support a model in which age-dependent alterations in gene expression at the stem cell level presage downstream developmental potential and thereby contribute to age-dependent immune decline, and perhaps also to the increased incidence of leukemia in the elderly.