Biology subjects

Paulson, R. F.

Publications and source records attributed to Paulson, R. F..

4 recordsLinked to original sources

bioRxiv2023

Itaconate promotes the differentiation of murine stress erythroid progenitors by increasing Nrf2 activity.

Steady state erythropoiesis produces new erythrocytes at a constant rate to replace senescent erythrocytes removed in the spleen and liver. Inflammation caused by infection or tissue damage skews bone marrow hematopoiesis, increasing myelopoiesis at the expense of steady state erythropoiesis. To compensate for the loss of production, stress erythropoiesis is induced. Stress erythropoiesis is highly conserved between mouse and human but utilizes a different strategy than steady state erythropoiesis. Inflammatory signals promote the proliferation of immature stress erythroid progenitors (SEPS), which in response to erythropoietin and other signals transition to stress erythroid progenitors committed to differentiation. Here we show that TNF dependent signaling increases ROS in SEPs during the proliferation stage, however, blocking ROS production impairs their later differentiation. In addition to TNF, nitric oxide dependent signaling drives the proliferation of stress erythroid progenitors and production of nitric oxide must be decreased so that the progenitor cells can differentiate. As progenitor cells transition to differentiation, increased production of the anti-inflammatory metabolite itaconate activates Nfe2l2 or Nrf2, which inhibits Nos2 expression, leading to decreased nitric oxide production. Mutation of Irg1, the enzyme that catalyzes the production of itaconate, causes a delayed recovery from inflammatory anemia induced by heat killed Brucella abortus. Loss of itaconate-dependent activation of Nrf2 is rescued in vivo by IL-10, which leads to activation of Nrf2 and differentiation. These data show that the differentiation of stress erythroid progenitors relies on a switch to an anti-inflammatory metabolism and increased expression of pro-resolving cytokines. Key points1. The transition to differentiation of stress erythroid progenitors requires anti-inflammatory signals. 2. The anti-inflammatory metabolite itaconate and IL-10 increase Nrf2 activity to promote the differentiation of stress erythroid progenitors.

developmental biology↗

bioRxiv2023

Nitric oxide regulates metabolism in murine stress erythroid progenitors to promote recovery during inflammatory anemia.

Inflammation skews bone marrow hematopoiesis increasing the production of myeloid effector cells at the expense of steady-state erythropoiesis. A compensatory stress erythropoiesis response is induced to maintain homeostasis until inflammation is resolved. In contrast to steady-state erythroid progenitors, stress erythroid progenitors (SEPs) utilize signals induced by inflammatory stimuli. However, the mechanistic basis for this is not clear. Here we reveal a nitric oxide (NO)-dependent regulatory network underlying two stages of stress erythropoiesis, namely proliferation, and the transition to differentiation. In the proliferative stage, immature SEPs and cells in the niche increased expression of inducible nitric oxide synthase (Nos2 or iNOS) to generate NO. Increased NO rewires SEP metabolism to increase anabolic pathways, which drive the biosynthesis of nucleotides, amino acids and other intermediates needed for cell division. This NO-dependent metabolism promotes cell proliferation while also inhibiting erythroid differentiation leading to the amplification of a large population of non-committed progenitors. The transition of these progenitors to differentiation is mediated by the activation of nuclear factor erythroid 2-related factor 2 (Nfe2l2 or Nrf2). Nrf2 acts as an anti-inflammatory regulator that decreases NO production, which removes the NO-dependent erythroid inhibition and allows for differentiation. These data provide a paradigm for how alterations in metabolism allow inflammatory signals to amplify immature progenitors prior to differentiation. Key pointsO_LINitric-oxide (NO) dependent signaling favors an anabolic metabolism that promotes proliferation and inhibits differentiation. C_LIO_LIActivation of Nfe2l2 (Nrf2) decreases NO production allowing erythroid differentiation. C_LI

developmental biology↗

bioRxiv2022

Intra-peritoneal transplantation for efficient and easy generation of experimental acute myeloid leukemia in mice

ObjectiveThere is an unmet need for novel therapies to treat acute myeloid leukemia (AML) and the associated relapse that involves leukemia stem cells (LSCs). An experimental AML rodent model to test therapies based on successfully transplanting these cells via retro-orbital injections in recipient mice is fraught with challenges. The aim of this study was to develop an easy, reliable, and consistent method to generate a robust murine model of AML using an intra-peritoneal route. MethodsBone marrow cells were transduced with a retrovirus expressing human MLL-AF9 fusion oncoprotein. Efficiency of lineage negative (Lin-) and Lin-Sca-1+c-Kit+ (LSK) populations as donor LSCs in the development of primary AML was tested. We developed a new method to generate AML by intra-peritoneal injection and discuss the pros and cons of intra-peritoneal and retro-orbital injections in serial transplantations. ResultsBoth Lin- and LSK cells transduced with human MLL-AF9 virus engrafted well in the bone marrow and spleen of recipients, leading to a full-blown AML. Intra-peritoneal injection of donor cells established AML in recipients upon serial transplantation.Infiltration of AML cells was detected in the blood, bone marrow, spleen, and liver of recipients by flow cytometry, qPCR, and histological analyses. ConclusionsO_LIIntra-peritoneal injection is an efficient method of AML induction using serial transplantation of donor cells. C_LIO_LIDelayed homing to bone marrow, seen in intra-peritoneal injection that impedes the progression of AML, can be easily overcome by increasing the number of transplanted donor cells. C_LIO_LIIncreasing the number of transplanted donor cells can also help shorten the duration of onset of AML. C_LIO_LISorting of LSK population within donor cells is not necessary in the generation of MLL-AF9-induced primary AML given that Lin- population are equally efficient as LSK donor cells in primary transplantation of AML in mice. C_LI

cancer biology↗

bioRxiv2018

The role of Selenoprotein N in the differentiation of erythroid progenitors during stress erythropoiesis

Low serum Se is independently associated with anemia in elderly population, dialysis patients, sickle-cells patients, and hypothyroidism patients. Previous work from our laboratory showed that dietary Se deficiency in mice showed mild anemia indicating activation of stress-erythropoietic mechanisms. Unlike steady state erythropoiesis that is primarily responsible for homeostasis to produce new erythrocytes at a constant rate, stress erythropoiesis predominates when the bone marrow cannot generate sufficient erythrocytes. During such a process, short-term reconstituting hematopoietic stem cells (CD34+Kit+Sca1+Linneg) migrate to the spleen leading to the proliferation and differentiation of stress-erythroid progenitors (SEPs). These cells lead to stress burst forming unit-erythroid cells (BFU-E) followed by terminal differentiation to erythrocytes. Recent studies demonstrate deficits in selenoproteins block the expansion and development of stress BFU-E with defects in terminal differentiation. Analysis of selenoprotein expression showed that selenoprotein W (SelenoW) was highly expressed in developing SEPs. CRISPR-Cas9 knockout of SelenoW blocked the proliferation of immature SEPs in murine and human stress erythropoiesis cultures demonstrating a central role for SelenoW in stress erythropoiesis. Using the two-culture system to generate SEPs, selenoprotein N (SelenoN) expression increased as the progenitors transition from self-renewing \"stem cell like\" progenitors to form committed erythroid progenitors. SelenoN-/- mice showed significantly slower erythroid recovery following phenylhydrazine (PHZ)-induced acute hemolytic anemia. As in the muscle satellite cells where SelenoN regulates cellular Ca2+ signaling, SelenoN may also regulate Ca2+ signaling in SEPs to modulate pathways of differentiation. In summary, these data suggest that multiple selenoproteins, including SelenoN and SelenoW, coordinately regulate stress erythropoiesis.

developmental biology↗