A role for intracellular and extracellular DEK in regulating hematopoiesis

PURPOSE OF REVIEW: Hematopoietic stem/progenitor cell fate decision during hematopoiesis is regulated by intracellular and extracellular signals such as transcription factors, growth factors, and cell-to-cell interactions. In this review, we explore the function of DEK, a nuclear phosphoprotein, on gene regulation. We also examine how DEK is secreted and internalized by cells, and discuss how both endogenous and extracellular DEK regulates hematopoiesis. Finally, we explore what currently is known about the regulation of DEK during inflammation. RECENT FINDINGS: DEK negatively regulates the proliferation of early myeloid progenitor cells but has a positive effect on the differentiation of mature myeloid cells. Inflammation regulates intracellular DEK concentrations with inflammatory stimuli enhancing DEK expression. Inflammation-induced nuclear factor-kappa B activation is regulated by DEK, resulting in changes in the production of other inflammatory molecules such as IL-8. Inflammatory stimuli in turn regulates DEK secretion by cells of hematopoietic origin. However, how inflammation-induced expression and secretion of DEK regulates hematopoiesis remains unknown. SUMMARY: Understanding how DEK regulates hematopoiesis under both homeostatic and inflammatory conditions may lead to a better understanding of the biology of HSCs and HPCs. Furthering our knowledge of the regulation of hematopoiesis will ultimately lead to new therapeutics that may increase the efficacy of hematopoietic stem cell transplantation

Mild Heat Treatment Primes Human CD34(+) Cord Blood Cells for Migration Toward SDF-1α and Enhances Engraftment in an NSG Mouse Model

Simple efforts are needed to enhance cord blood (CB) transplantation. We hypothesized that short-term exposure of CD34(+) CB cells to 39.5°C would enhance their response to stromal-derived factor-1 (SDF-1), by increasing lipid raft aggregation and CXCR4 expression, thus leading to enhanced engraftment. Mild hyperthermia (39.5°C) significantly increased the percent of CD34(+) CB that migrated toward SDF-1. This was associated with increased expression of CXCR4 on the cells. Mechanistically, mild heating increased the percent of CD34(+) cells with aggregated lipid rafts and enhanced colocalization of CXCR4 within lipid raft domains. Using methyl-β-cyclodextrin (MβCD), an agent that blocks lipid raft aggregation, it was determined that this enhancement in chemotaxis was dependent upon lipid raft aggregation. Colocalization of Rac1, a GTPase crucial for cell migration and adhesion, with CXCR4 to the lipid raft was essential for the effects of heat on chemotaxis, as determined with an inhibitor of Rac1 activation, NSC23766. Application-wise, mild heat treatment significantly increased the percent chimerism as well as homing and engraftment of CD34(+) CB cells in sublethally irradiated non-obese diabetic severe combined immunodeficiency IL-2 receptor gamma chain d (NSG) mice. Mild heating may be a simple and inexpensive means to enhance engraftment following CB transplantation in patients

Mad2 Haploinsufficiency Protects Hematopoietic Progenitor Cells Subjected to Cell Cycle Stress In Vivo and to Inhibition of Redox Function of Ape1/Ref-1 In Vitro

Objective Cell-cycle checkpoints guarantee movement through the cell cycle. Mitotic arrest deficiency 2 (Mad2), a mitotic checkpoint protein, appears crucial for generating the wait anaphase signal to prevent onset of anaphase. We evaluated effects of Mad2 haploinsufficiency on hematopoietic stem (HSC) and progenitor (HPC) function in response to stress. Materials and Methods We studied effects of Mad2+/− on in vivo recovery of bone marrow HPC from cytotoxic effects and also effects of cytostatic agents on HPC growth in vitro using Mad2+/− mice. Results Mad2+/− HPCs were protected from cytotoxic effects in vivo of a cell-cycle−specific agent, Ara-C, events consistent with Mad2+/− HPCs being in a slow or noncycling state, but not from recovery of functional HPC after treatment with non-cycle−specific cyclophosphamide or sublethal irradiation. There were no differences in phenotyped HSCs in Mad2+/− & Mad2+/+ mice, information confirmed by no changes in short- or long-term repopulating HSC assay. To better understand Mad2+/− HPC function, E3330, a cytostatic agent, was used to assess redox function of Ape1/Ref-1; colony growth was examined under 5% and 20% O2 tension. Mad2+/− HPCs were less responsive to E3330 than Mad2+/+ HPCs, and E3330 was more effective under lowered O2 tension. Mad2+/− HPCs were not enhanced at lowered oxygen, as were Mad2+/+ HPCs. Conclusions Our studies have unexpectedly found that Mad2 haploinsufficiency is protective in the presence of a cycle-specific DNA synthesis agent in vivo, and Ape1/Ref-1 inhibitor in vitro

CaMKK2 Knockout Bone Marrow Cells Collected/Processed in Low Oxygen (Physioxia) Suggests CaMKK2 as a Hematopoietic Stem to Progenitor Differentiation Fate Determinant

Little is known about a regulatory role of CaMKK2 for hematopoietic stem (HSC) and progenitor (HPC) cell function. To assess this, we used Camkk2−/− and wild type (WT) control mouse bone marrow (BM) cells. BM cells were collected/processed and compared under hypoxia (3% oxygen; physioxia) vs. ambient air (~21% oxygen). Subjecting cells collected to ambient air, even for a few minutes, causes a stress that we termed Extra Physiological Shock/Stress (EPHOSS) that causes differentiation of HSCs and HPCs. We consider physioxia collection/processing a more relevant way to assess HSC/HPC numbers and function, as the cells remain in an oxygen tension closer physiologic conditions. Camkk2−/− cells collected/processed at 3% oxygen had positive and negative effects respectively on HSCs (by engraftment using competitive transplantation with congenic donor and competitor cells and lethally irradiated congenic recipient mice), and HPCs (by colony forming assays of CFU-GM, BFU-E, and CFU-GEMM) compared to WT cells processed in ambient air. Thus, with cells collected/processed under physioxia, and therefore never exposed and naïve to ambient air conditions, CaMKK2 not only appears to act as an HSC to HPC differentiation fate determinant, but as we found for other intracellular mediators, the Camkk−/− mouse BM cells were relatively resistant to effects of EPHOSS. This information is of potential use for modulation of WT BM HSCs and HPCs for future clinical advantage. Graphical Abstract: [Figure not available: see fulltext.]

Further Evidence for Cancer as a Cell-Wall- Deficient Mycobacterial Disease

In 2014, Buehring reported that Bovine Leukemic Virus (BLV), a common oncogenic retrovirus of cattle, was present in some humans, primarily localized to the breast epithelium ― the very cell type from which most breast malignancies arise. By 2015, there appeared data (Buehring, 2015) supporting that as many as 37% of human breast cancer cases could be attributable to BLV exposure. But if recent estimates suggest over 83% of U.S. dairy operations are currently positive for BLV, they also show that approximately 68% are positive for cell-wall-deficient Mycobacterium avium subspecies paratuberculosis (MAP). Although tubercular lung infection has been said to cause 11 times the incidence of lung cancer as normal control subjects, it is its cell-wall-deficient (CWD) forms (also called L-forms) that have recently repeatedly been found through genetic analysis and appropriate stains in such cancer tissue ― suggesting that CWD tuberculosis or atypical tuberculosis " is likely to be involved in the occurrence or development of lung carcinoma ". A similar relationship between tubercular L-forms and the genesis of the very breast cancer addressed in the aforementioned BLV viral trials. This is not a coincidence. L-forms (CWD forms) predominate and are crucial to the survival of mycobacteria in vivo and they have been documented by fluorescence microscopy in all intracellular macrophage-grown M. tuberculosis observed. From its origin, the very concept of the " BLV leukemic virus" has been on shaky, unstable ground. In 1969, veterinarians Janice and Lyle Miller from the University of Wisconsin-Madison spotted C-shaped " virus-like " particles in cattle lymposarcoma insisting that these were similar to other C-type viruses " regarded as the cause of leukemia in other species. " But by 1978, scientists at Downstate reported atypical mycobacterial forms, including its preferred filterable virus-sized " L " or cell-wall-deficient (CWD) forms in not only leukemia but all other malignancies ― all having, as their common denominator the continuous presence of mycobacterial C-shaped forms. Tracing back to techniques similar to Miller and Millers original BLV study we found in the very lyophilized antigens present in commercial kits for the diagnosis of BLV (AgBLV), these very same CWD (cell-wall-deficient) mycobacteria and mycobacterial DNA in all BLV samples ― which when introduced into guinea pigs stimulated the same antibody as occurred when mycobacteria-infected internal organ homogenates themselves were injected into other guinea pigs. It is therefore assumed that the Bovine Leukemic Virus (BLV) is being mistaken for viral-like forms of cell-wall-deficient (CWD) atypical tubercular mycobacteria. Since latent tubercular infection, as well as the administration of BCG and tuberculin also results in persistent CWD forms, their possible role in carcinogenesis is also considered

Ames hypopituitary dwarf mice demonstrate imbalanced myelopoiesis between bone marrow and spleen

Ames hypopituitary dwarf mice are deficient in growth hormone, thyroid-stimulating hormone, and prolactin. The phenotype of these mice demonstrates irregularities in the immune system with skewing of the normal cytokine milieu towards a more anti-inflammatory environment. However, the hematopoietic stem and progenitor cell composition of the bone marrow (BM) and spleen in Ames dwarf mice has not been well characterized. We found that there was a significant decrease in overall cell count when comparing the BM and spleen of 4-5 month old dwarf mice to their littermate controls. Upon adjusting counts to differences in body weight between the dwarf and control mice, the number of granulocyte-macrophage progenitors, confirmed by immunophenotyping and colony-formation assay was increased in the BM. In contrast, the numbers of all myeloid progenitor populations in the spleen were greatly reduced, as confirmed by colony-formation assays. This suggests that there is a shift of myelopoiesis from the spleen to the BM of Ames dwarf mice; however, this shift does not appear to involve erythropoiesis. The reasons for this unusual shift in spleen to marrow hematopoiesis in Ames dwarf mice are yet to be determined but may relate to the decreased hormone levels in these mice

Glucose-independent Acetate Metabolism Promotes Melanoma Cell Survival and Tumor Growth

Tumors rely on multiple nutrients to meet cellular bioenergetics and macromolecular synthesis demands of rapidly dividing cells. Although the role of glucose and glutamine in cancer metabolism is well understood, the relative contribution of acetate metabolism remains to be clarified. We show that glutamine supplementation is not sufficient to prevent loss of cell viability in a subset of glucose-deprived melanoma cells, but synergizes with acetate to support cell survival. Glucose-deprived melanoma cells depend on both oxidative phosphorylation and acetate metabolism for cell survival. Acetate supplementation significantly contributed to maintenance of ATP levels in glucose-starved cells. Unlike acetate, short chain fatty acids such as butyrate and propionate failed to prevent loss of cell viability from glucose deprivation. In vivo studies revealed that in addition to nucleo-cytoplasmic acetate assimilating enzyme ACSS2, mitochondrial ACSS1 was critical for melanoma tumor growth in mice. Our data indicate that acetate metabolism may be a potential therapeutic target for BRAF mutant melanoma

Enhanced Collection of Phenotypic and Engrafting Human Cord Blood Hematopoietic Stem Cells at 4°C

The number of hematopoietic stem cells (HSCs) collected in cord blood (CB) at the birth of a baby is a limiting factor for efficacious use of CB in hematopoietic cell transplantation (HCT). We now demonstrate that collecting and processing of human CB at 4°C within minutes of the baby's birth results in significantly enhanced numbers of rigorously defined phenotypic HSC and self-renewing NSG immune-deficient mouse engrafting and SCID-repopulating cells. This was associated with decreased numbers of hematopoietic progenitor cells (HPC), as noted previously for hypoxia collected/processed cells blocking ambient air induced differentiation of HSC to HPC. We have thus defined a simple, cost-effective, means to collect increased numbers of CB HSC, of potential use for clinical CB HCT

CWD Tuberculosis Found in Spongiform Disease Formerly Attributed to Prions: Its Implication towards Mad Cow Disease, Scrapie and Alzheimer's

The TSE'S or transmissible spongiform enchephalopathies, include bovine spongiform encephalopathy (also called BSE or " mad cow disease "), Creutzfeldt– Jakob disease (CJD) in humans, and " scrapie " in sheep or goats (caprine spongiform encephalopathy). They remain a mystery, their cause still hotly debated. Current mad cow diagnosis lies solely in the detection of late appearing " prions " , an acronym for hypothesized, geneless, misfolded proteins, somehow claimed to cause the disease. Yet laboratory preparations of prions contain other things, which could include unidentified bacteria or viruses. And the only real evidence that prion originator Stanley Prusiner had in his original paper that the disease agent behind " Scrapie " in sheep and goats was devoid of DNA or RNA– was based upon the fact that he couldn't find any. Furthermore, the rigors of prion purification alone, might, in and of themselves, have killed any causative microorganism and Heino Dringer, who did pioneer work on their nature, candidly predicts " it will turn out that the prion concept is wrong. " Roels and Walravens as well as Hartly traced Mad Cow to Mycobacterium bovis. Moreover, epidemiologic maps of the origins and peak incidence of Mad Cow in the UK, suggestively match those of England's areas of highest bovine tuberculosis, the Southwest. The neurotaxic potential of bovine tuberculosis has for some time been well known. By 1911 Alois Alzheimer called attention to " a characteristic condition of the cortical tissue which Fischer referred to as 'spongy cortical wasting " in Alzheimer's disease (AD). But behind AD, Fischer suspected a microbe called Streptothrix which was constantly being mistaken and confused for tuberculosis. Our present investigation of the TSEs clearly shows cell-wall-deficient (CWD) tubercular mycobacteria present, verified by molecular analysis, ELISA, PCR and microscopy to cause spongiform encephalopathy

HUMAN ADIPOSE-DERIVED STEM CELLS ATTENUATE CIGARETTE SMOKE INDUCED BONE MARROW HYPOPLASIA VIA SECRETION OF ANTI-INFLAMMATORY CYTOKINE TSG-6

poster abstractIntroduction We have previously observed bone marrow (BM) hypo-plasia in a murine model of chronic smoking, which was ameliorated by mu-rine adipose-derived stromal cells (ASC). This study was designed to test the hypothesis that ASC exert their marrow protective effects through key paracrine factors. Methods Mice (NSG or C57BL/6) were exposed to ciga-rette smoke (CS) for 1 day to 6 months. Human ASC or ASC conditioned media were administered through intravenous (i.v.) or intraperitoneal (i.p.) injections. Secretion of TSG-6 from ASC in response to TNF alpha and IL-1 beta were measured by ELISA. Expression of TSG-6 in ASC was knocked down by siRNA. BM hematopoietic progenitors were quantified by colony forming-unit assays. Possible engrafted human ASC in mouse BM were ex-amined by anti-human nuclei staining. Results The myelossupressive effect of cigarette smoking occurred acutely (1 day: 65.6% of nonsmoking control, NSC, p0.05) or ASC conditioned media (105.7% NSC, p>0.05). Inflammatory cytokines (TNF alpha and IL-1 beta) elevated in smokers (Kuschner et al, 1996; de Maat et al, 2002) demonstrated strong cross-species stimulatory effects on secretions of an anti-inflammatory cytokine, TSG-6 from ASC (TNF alpha: 8.7 +/- 1.3 fold, IL-1 beta: 8.2 +/- 1.1 fold). Knocking down TSG-6 (>90%) abolished the marrow-protective effect of ASC. No human cells were detected in recipient mouse bone marrow. Conclusions The pro-tective effects of ASC against smoking-induced myelosuppression are medi-ated by trophic factors rather than cell engraftment or differentiation. TSG-6 appears to play a significant role in the modulatory pathway: smoke--inflammatory cytokine release--TSG6 secretion from ASC--bone marrow protection