P&F Projects 2022




Guo Abstract Type A P&F 2023


Proliferation followed by differentiation of the granulocyte and macrophage progenitors (GMPs) sustains the rapid cellular turnover of the myeloid lineages. Their essentiality is highlighted by the side effects of many chemotherapy drugs designed to target the proliferating cancer cells. This highly proliferative state, however, is transient for a given GMP cell, which exits from the proliferative state upon differentiation. My lab previously found that GMPs divide every 6-8 hours at their peak proliferative state, and this state lasts for ~1-2 days, at least in vitro, when cell cycle slows upon differentiation. These proliferative progenitors possess enormous regenerative potential; agents that can tap into this regenerative power without transformation would provide ample therapeutic opportunities. In our search for such agents, we discovered a small molecule to yield orders of magnitude more expansion without impairing subsequent differentiation. While experiments are being planned to test its effect in vivo, we propose to identify the molecular target(s) for this small molecule compound. We have teamed up with renowned Yale experts in medicinal chemistry and target identification, Dr. Craig Crews, and have obtained critical evidence to support that this compound may act by metabolic reprogramming. Therefore, we seek the CCEH Type A support from the University of Utah Metabolomics Core to test our hypothesis. Overall, the experiments in this proposal could unveil a novel class of chemical agents with pharmacologic potential for hematopoietic regeneration.




Scalf Abstract Type B P&F 2022


Proliferation followed by differentiation of the granulocyte and macrophage progenitors (GMPs) sustains the rapid cellular turnover of the myeloid lineages. Their essentiality is highlighted by the side effects of many chemotherapy drugs designed to target the proliferating cancer cells. This highly proliferative state, however, is transient for a given GMP cell, which exits from the proliferative state upon differentiation. My lab previously found that GMPs divide every 6-8 hours at their peak proliferative state, and this state lasts for ~1-2 days, at least in vitro, when cell cycle slows upon differentiation. These proliferative progenitors possess enormous regenerative potential; agents that can tap into this regenerative power without transformation would provide ample therapeutic opportunities. In our search for such agents, I discovered a small molecule to display such activity, yielding orders of magnitude more expansion without impairing subsequent differentiation. My proposal is to identify the molecular target(s) for the small molecule and to test whether it can promote hematopoietic recovery following injury in vivo. We have teamed up with renowned Yale experts in medicinal chemistry and target identification, Dr. Craig Crews, and have obtained critical evidence to support feasibility using a targeted proteomic approach to unveil the molecular target(s)/mechanism for the small molecule. In a second aim as supported by encouraging preliminary results, I will administer the small molecule to mice post irradiation and 5’ fluorouracil to test whether it promotes hematopoietic/myeloid recovery post injury. Overall, the experiments in this proposal could unveil a novel class of chemical agents with pharmacologic potential for hematopoietic regeneration.




Klein Abstract Type B P&F 2022


This collaborative proposal targets fatty acid oxidation (FAO) to expand human hematopoietic stem cells (HSCs) in chemically defined culture conditions. Independent research paths in the Tong and Klein labs have converged on the unexpected finding that FAO activation enhances HSC function during ex vivo expansion. The Tong lab has found that genetic disruption of the adaptor protein LNK, which expands long-term HSCs >10-fold, activates a metabolic program that increases FAO and reduces oxidative stress. Independently, a high throughput screen in the Klein lab identified drugs that induce FAO through activation of PPARa as potent enhancers of ex vivo HSC expansion. Here we propose to test the hypothesis that FAO activation is required for HSC expansion and that PPARa agonists can be used for therapeutic HSC expansion ex vivo. Investigation of metabolic regulators of hematopoiesis is a new area of research for both the Tong and Klein labs that could have substantial therapeutic impact. The significance of this proposal includes: 1. The ability to expand human HSCs in umbilical cord blood units will substantially increase the number of available HLA matches for patients needing HSC transplant, notably patients with myelodysplastia, advanced myeloproliferative disorders, and bone marrow failure. 2. Gene editing techniques for the treatment of inherited blood disorders are limited by the loss of long term (LT)-HSCs during ex vivo manipulations; our low cytokine culture conditions maintain LT-HSCs ex vivo without loss of reconstituting activity, providing an ideal platform for therapeutic gene editing. At a basic science level, our preliminary data and published work from others identify a role for FAO in the maintenance of LT-HSCs. However, the mechanisms by which FAO enhances HSC function have not been explored. Furthermore, while PPARa agonists are widely used clinically to treat hyperlipidemia (e.g. gemfibrozil/lopid), these drugs have not previously been applied to therapeutic HSC expansion. Our data are too preliminary for an R01 submission; these high risk/high gain experiments will require transplantation studies in mice and additional metabolic analyses to support a collaborative R01 submission to the NIDDK in the future.




Karnik Abstract Type A P&F 2022


Bone marrow (BM) is the primary site of hematopoiesis in mammals and where hematopoietic stem cells (HSCs) reside. As the age advances, the BM architecture changes and the hematopoietic potential of HSCs declines. The pathways involved with this decline in HSC regenerative potential are not fully understood. However, we know that from previous studies by our group and others on dissociated bone marrow, the cells of the hematopoietic niche (HN) such as osteomacs (OMs), megakaryocytes (MKs), and osteoblasts (OBs) are involved in maintaining the HSC function. These studies use established techniques such as flow cytometry and immunofluorescence which use dissociated BM either to quantify the cells of the HN or the tissue to visualize up to three cell markers at a time. However, it is important to understand the spatial relationships of the cells of the HN with each other in an unperturbed BM to better comprehend the interactions of these cells in the BM niche and how they change as the age advances. A multiplex high-resolution imaging technology, CODEX, that can visualize up to 60 markers simultaneously can overcome the limitations of traditional techniques to visualize the entire niche. We propose to use the CODEX to image the HN to study the spatial relationships between the cells of HN in young and old mice to better understand the HN architectural landscape and to develop the methodology for CODEX use so it can become a research and investigative tool for other hematology investigators. Plotting the architectural landscape of the BM of both young and old mice will enhance our understanding of the relationship between these cells in the BM niche and to help us develop the methodology and protocols of the CODEX so it can become a research and investigative tool for non-malignant hematology investigators.




Leibold Abstract Type A P&F 2022


Due to its presence in proteins involved in hemoglobin synthesis, DNA synthesis and mitochondrial respiration, eukaryotic cells require iron for growth and proliferation.  Regulation of cellular iron content is crucial: excess cellular iron catalyzes the generation of reactive oxygen species  that damage DNA and proteins, while cellular iron deficiency causes cell cycle arrest and cell death. Dysregulation of iron homeostasis caused by iron deficiency or iron excess leads to hematological, neurodegenerative and metabolic disorders. Vertebrate iron metabolism is controlled post-transcriptionally by iron-regulatory protein 2 (Irp2). Irp2 binds to iron-responsive elements (IREs) in the mRNAs of proteins involved in iron uptake (transferrin receptor 1), sequestration (ferritin) and export (ferroportin), and regulates the translation or stability of these mRNAs. Our previous work show that Irp2 is regulated by iron-dependent proteolysis by the FBXL5 SCF-ubiquitin ligase. We also discovered a novel iron-independent mechanism for regulating Irp2 RNA-binding activity during the cell cycle. Irp2 is phosphorylated at S157 by Cdk1/cyclin B during G2/M and dephosphorylated by Cdc14A during mitotic exit. Irp2-S157 phosphorylation blocks its interaction with RNA to increase ferritin synthesis and decrease TfR1 mRNA stability during mitosis. The significance of  S157 phosphorylation was investigated in mice where Ser157 was mutated to Ala157 (Irp2A/A)). Irp2A/A mice display anemia, defective erythroid terminal differentiation and dysregulated systemic iron metabolism. Our overall objective is to determine the role of Irp2-S157 phosphorylation in hematopoiesis. Our goal here is characterize the anemia in WT and Irp2A/A mice. For these studies, we propose to utilize the University of Utah Center for Iron & Heme Disorders Core for quantification of iron and heme content in tissue samples from WT and Irp2A/A mice.




Mayday Abstract Type B P&F 2022


RNA binding motif protein 15 (RBM15) is a key regulator of N6-methyladenosine (m6A) epitranscriptome modification and is essential for recruitment of the m6A writer protein complex to target RNAs. It has been shown that RBM15 is important for hematopoietic stem cell (HSC) maintenance and quiescence, but its role in the fate specification of hematopoietic progenitor cells (HPCs) remains poorly understood. RBM15 is part of the recurrent t(1;22) translocation associated with infantile acute megakaryoblastic leukemia; therefore, investigation into its role in megakaryocyte differentiation and maturation is warranted. Understanding the mechanistic role of RBM15 in the process of megakaryocyte maturation will not only provide potential avenues of investigation for treatment of AMKL but will also shed light on the role of this protein and the m6A epitranscriptome in megakaryopoiesis. This proposal aims to understand the transcriptomic targets of RBM15 (Aim 1) and the m6A epitranscriptomic modifications regulated by RBM15 (Aim 2) in a model of megakaryopoiesis. Using enhanced crosslinking and immunoprecipitation sequencing techniques, we will characterize these targets at single nucleotide resolution. Comparison to RNA-seq will provide insight into the consequences of RBM15 binding and modification on target transcripts. By determining the exact nucleotide bound by RBM15 and the exact adenosine modified nearby, we will gain detailed insight into the epitranscriptome dynamics involved in hematopoietic differentiation. Completion of this project will illuminate the transcriptome and epitranscriptome interactions of RBM15 and will provide candidate genes that may be critical for downstream mechanistic effects driving megakaryopoiesis. By filling gaps in the field, this work will lay the foundation for further investigation of the epitranscriptome in hematopoietic fate decision.




Prasada Rao Jarajapu Abstract Type B P&F 2022


Diabetes increases risk for cardiovascular diseases. Chronic inflammation and oxidative stress appear to be underlying mechanisms of diabetic dysfunction in cardiovascular tissues. Systemic inflammation is due to myelopoietic bias in the stem/progenitor cells and the resulting increased generation of pro-inflammatory monocyte-macrophages. TERT is a subunit of telomerase that is responsible for telomere maintenance and chromosomal stability. Independent of telomerase, TERT regulates hematopoiesis and mitochondrial functions. Our preliminary studies discovered that diabetic CD34+ hematopoietic stem/progenitor cells (HSPCs) express one or more deletion variants of TERT, őĪ-, ő≤- or őĪő≤-variants, while nondiabetic cells do not. Deletion variants of TERT are known to oppose full-length TERT function. The presence of variants correlated with decreased telomerase activity and elevated mitochondrial reactive oxygen species (mitoROS) in diabetic CD34+ cells compared to the nondiabetic. Furthermore, we found that silencing of TGFÔĀĘ1 blocked TERT-splicing that accompanied decreased mitoROS and reversed myelopoiesis. This pilot proposal tests the hypothesis that splice variants of TERT mediate increased myelopoiesis and mitochondrial oxidative stress in diabetic CD34+ HSPCs. Splice variants will be silenced by using morpholino-oligonucleotide sequences complementary to specific intron-exon or exon-intron boundaries of the TERT pre-mRNA sequence of TERT, which block the alternate splice sites őĪ- (intron 5/exon 6) and ő≤- (intron 6/exon 7). We will test the impact of this molecular modification on myelopoietic potential in ex vivo and in vivo. A novel mouse model NSGS mouse that support myelopoietic differentiation of human CD34+ cells will be used. Beneficial effects of the TERT variants‚Äô knockdown on mitochondrial functions including oxidative stress, metabolism - glycolysis and oxidative phosphorylation, and mitoDNA damage will be evaluated. This pilot study will enhance our understanding of TERT physiology in diabetic HSPC




Xiao Abstract Type B P&F 2022


Iron is an essential micronutrient required for many biological processes, including erythropoiesis, but excess iron is toxic due to its ability to generate reactive oxygen species. Aberrant regulation of the master iron hormone hepcidin is a major underlying cause of most iron disorders including anemia of chronic disease, iron refractory iron deficiency anemia, beta-thalassemia, and hemochromatosis. Hepcidin functions by binding and inducing degradation of the sole iron exporter ferroportin to reduce iron influx into the circulation from dietary sources and body stores. Liver hepcidin expression is regulated by several different signals that indicate whether the body needs more or less iron, including serum and tissue iron levels, erythropoietic drive, and inflammation. Previous studies have discovered that the bone morphogenetic protein (BMP)-SMAD signaling pathway is a central regulator of hepcidin transcription in response to most of its known signals. However, there are many facets of hepcidin regulation that are still not understood, including how hepcidin is regulated by homeostatic iron regulator HFE. Mutations in HFE are the most common cause of hereditary hemochromatosis, an autosomal recessive iron overload disorder with a prevalence of 1 in 300 individuals in the United States. Although HFE mutations were linked to hereditary hemochromatosis over 20 years ago, the precise mechanisms of action of HFE in hepcidin regulation are still unclear. The current working model is that HFE deficiency leads to impaired SMAD signaling responses to BMP ligands. In the current proposal, preliminary data will be presented using a novel mouse model demonstrating that HFE also regulates hepcidin through a SMAD-independent pathway. Herein, I propose to perform bulk RNA sequencing (Seq) and single cell RNA-seq in this mouse model as a discovery approach to identify the unknown SMAD-independent signaling pathway(s) governing hepcidin regulation by HFE. This work holds the promise to shift the paradigm in understanding the mechanism of action of HFE and to discover a novel signaling pathway governing hepcidin and iron homeostasis regulation that may ultimately identify new therapeutic targets for treating iron disorders.





Belot Abstract Type B P&F 2022


Heme, an iron-containing organic ring, is a vital cofactor responsible for diverse biological functions and is the major source of bioavailable iron in the human diet. The current dogma states that mammalian heme levels within cells are controlled by balance between heme biosynthesis and heme catabolism. In the past few years, the Hamza lab has led the field by contributing to the discovery of eukaryotic heme transporters and heme trafficking pathways. Our overarching, paradigm-shifting hypothesis is that cellular heme levels are not only maintained by internal heme synthesis (cell-autonomous), but also by distally located proteins which signal systemic heme requirements to a heme trafficking network (cell-nonautonomous). Although emerging evidence supports the existence of a cell-nonautonomous heme communication system in mammals, this concept has remained unexplored. Our recent preliminary studies have revealed an unexpected and novel finding that adult mice under heme depletion and acute need for red blood cells production upregulate erythroid HRG1 expression. This strongly suggests that heme homeostasis during erythropoiesis involves previously unappreciated mechanism(s). Thus, the overall goal of the proposed studies is to use stress erythropoiesis condition (chronic phlebotomies) in different mouse model (WT, HRG1 KO, HRG1EpoR/EpoR mice) to elucidate whether HRG1 heme importer could participate in hemoglobinization of red blood cells.  We plan to (a) elucidate the role of HRG1 in erythroid progenitors, and (b) identify the heme-responsive cell-nonautonomous pathway using RNA-seq in WT and HRG1-KO mice.