ALBERT

Description: Author(s): K. A. Ross, L. R. Yaraskavitch, M. Laver, J. S. Gardner, J. A. Quilliam, S. Meng, J. B. Kycia, D. K. Singh, Th. Proffen, H. A. Dabkowska, and B. D. Gaulin [Phys. Rev. B 84, 174442] Published Wed Nov 30, 2011

Description: Despite studies that have investigated the interactions of double-stranded RNA-binding proteins like Staufen with RNA in vitro , how they achieve target specificity in vivo remains uncertain. We performed RNA co-immunoprecipitations followed by microarray analysis to identify Staufen-associated mRNAs in early Drosophila embryos. Analysis of the localization and functions of these transcripts revealed a number of potentially novel roles for Staufen. Using computational methods, we identified two sequence features that distinguish Staufen’s target transcripts from non-targets. First, these Drosophila transcripts, as well as those human transcripts bound by human Staufen1 and 2, have 3' untranslated regions (UTRs) that are 3–4-fold longer than unbound transcripts. Second, the 3'UTRs of Staufen-bound transcripts are highly enriched for three types of secondary structures. These structures map with high precision to previously identified Staufen-binding regions in Drosophila bicoid and human ARF1 3'UTRs. Our results provide the first systematic genome-wide analysis showing how a double-stranded RNA-binding protein achieves target specificity.

Description: The origin of marrow stromal cells post allogeneic bone marrow transplantation (BMT) was studied. Two groups of patients receiving HLA- identical marrow grafts from sex mismatched siblings were included in the study: the first group (eight patients) received conventional marrow grafts and the second group (ten patients) received stromal cell and T cell depleted grafts. All patients showed hematopoietic engraftment with donor cells. Marrow aspirates obtained from these patients were used to establish stromal layers in long-term marrow cultures (LTMC) for 4 to 6 weeks. In both groups, karyotype analysis of nonhematopoietic cultured stromal cells showed host origin even as late as day 760 posttransplantation. Immunofluorescence methods using monoclonal antibodies against components of fibroblasts, macrophages, and endothelial cells, showed that the composition of stromal layers was similar to those obtained from normal controls. Our data indicate that marrow stromal progenitors capable of proliferation are nontransplantable and do not originate from a hematopoietic-stromal common progenitor.

Description: The origin of marrow stromal cells post allogeneic bone marrow transplantation (BMT) was studied. Two groups of patients receiving HLA- identical marrow grafts from sex mismatched siblings were included in the study: the first group (eight patients) received conventional marrow grafts and the second group (ten patients) received stromal cell and T cell depleted grafts. All patients showed hematopoietic engraftment with donor cells. Marrow aspirates obtained from these patients were used to establish stromal layers in long-term marrow cultures (LTMC) for 4 to 6 weeks. In both groups, karyotype analysis of nonhematopoietic cultured stromal cells showed host origin even as late as day 760 posttransplantation. Immunofluorescence methods using monoclonal antibodies against components of fibroblasts, macrophages, and endothelial cells, showed that the composition of stromal layers was similar to those obtained from normal controls. Our data indicate that marrow stromal progenitors capable of proliferation are nontransplantable and do not originate from a hematopoietic-stromal common progenitor.

Description: The effects of recombinant human interleukin-1 rhIL-1 beta (rhIL-1b) on hematopoietic recovery following chemotherapy in a primate model were investigated. Cynomolgus monkeys received 1 microgram/kg/day rhIL-1b intravenously for 2, 7, and 14 days following 5-Fluorouracil (5-FU) treatment (75 mg/kg x 2 days). Compared with controls, a significantly shortened time to achieve an absolute neutrophil (ANC) count over 500/microL was observed in animals receiving 2- and 7-day courses of rhIL-1b (17 v 30 days), while animals receiving a 14-day course of rhIL- 1b achieved an ANC over 500/microL by 23 days. Concomitantly, a marked increase in granulocyte-macrophage colonies (CFU-GM) was observed at 14 days following 5-FU in animals receiving 2- and 7-day rhIL-1b courses. In animals receiving a 14-day rhIL-1b course, a significant increase in CFU-GM relative to control was not seen until 21 days post 5-FU. Utilizing a serum-free colony assay system, a 50% inhibition of normal marrow CFU-GM growth was observed with the addition of sera obtained on day 9 post 5-FU from animals receiving rhIL-1b for 14 days. Sera obtained at any time from animals receiving 2- and 7-day rhIL-1b treatment did not show any growth inhibition. Addition of antibodies to TNFa to the coculture assay abrogated the CFU-GM growth inhibition. TNFa levels in sera with the inhibitory activity was relatively high (918 pg/mL). Our data indicate that rhIL-1b enhances hematopoietic recovery following 5-FU if administered for short periods of time (less than 7 days), whereas prolonged administration has a counterproductive effect that is due in part to the induction of TNFa production.

Description: Folylpolyglutamate synthetase (FPGS) is responsible for the metabolism of natural folates and a broad range of folate antagonists to polyglutamate derivatives. Recent studies indicated increased accumulation of methotrexate (MTX) polyglutamates (MTX-PG) in blast cells as a predictor of favorable treatment outcome in childhood acute lymphoblastic leukemia (ALL). We determined the expression of FPGS activity in blasts from children with ALL at diagnosis and after treatment with MTX as a single agent, before conventional remission induction therapy. The levels of enzyme activity in ALL blasts at diagnosis (median of 689 pmol/h/mg protein) were significantly higher (P = .003) than those found in acute nonlymphoblastic leukemia (ANLL) blasts (median of 181 pmol/h/mg protein). Comparable lineage differences in normal lymphoid versus nonlymphoid cells suggest a lineage-specific control of FPGS expression, FPGS activity increased in ALL blasts after in vivo exposure to MTX. The median increase in FPGS activity was significantly higher (P = .003) in B-lineage ALL (188%) than in T-lineage ALL (37%). Likewise, the percentage of intracellular long chain MTX-PG (Glu3–6) was significantly higher (P = .02) in B- lineage ALL (92%) than in T-lineage ALL (65%), consistent with higher FPGS activity in B-lineage blasts. This finding could explain, at least in part, the superior outcome in children with B-lineage ALL treated with antimetabolite therapy.

Description: We describe the effects of in vitro irradiation on the proliferative capacity and hematopoietic supportive function of human marrow stromal cells. To assess the effects on the proliferative capacity of stromal progenitors and differentiated fibroblasts, marrow cell suspensions and trypsin-dispersed marrow fibroblasts were treated with a single dose of gamma radiation at 100 rad/min. Fibroblastic progenitors (CFU-F) showed an exponential decrease in colony formation with increasing doses of irradiation, with a Do slightly higher than that of granulomonopoietic progenitors (CFU-GM); Do values for CFU-F and CFU-GM were 130 and 115, respectively. However, although the CFU-F survival curve exhibited a shoulder (n = 1.3), the CFU-GM curve did not (n = 1.0), indicating that only fibroblastic progenitors have the potential to repair irradiation- induced damage. Passaged marrow fibroblast colony-forming cells also showed a shouldered exponential survival curve with a Do of 110 and n value of 1.4. Marrow stromal progenitors giving rise to adherent layers in long-term marrow cultures also demonstrated a highly radiosensitive proliferative capacity. Stromal layers derived from irradiated marrow suspensions failed to establish adherent layers after relatively low doses of irradiation (over 240 rad) in a dose-response manner. To assess any functional damage in stromal progenitors surviving irradiation, stromal layers derived from marrow suspensions irradiated up to 240 rad were cocultured with freshly isolated autologous hematopoietic cells and assayed for their capacity to support prolonged CFU-GM production. Confluent stromal layers derived from irradiated marrow suspensions sustained CFU-GM production as well as controls. To study the effects of irradiation on the hematopoietic supportive capacity of established marrow-derived stromal layers, 4 to 6-week-old adherent layers were irradiated as described and cocultured with autologous marrow cells enriched for colony-forming cells. Stromal layers irradiated up to 1,320 rad sustained prolonged CFU-GM production, indicating that the hematopoietic supportive function remained intact at this dose of irradiation. In conclusion, we demonstrated that the proliferative capacity of human marrow stromal progenitors, as well as that of their differentiated descendants, is quite sensitive to in vitro radiation, while the hematopoietic supportive function of differentiated stromal cells is relatively resistant to the effects of radiation.

Description: The effects of recombinant human interleukin-1 rhIL-1 beta (rhIL-1b) on hematopoietic recovery following chemotherapy in a primate model were investigated. Cynomolgus monkeys received 1 microgram/kg/day rhIL-1b intravenously for 2, 7, and 14 days following 5-Fluorouracil (5-FU) treatment (75 mg/kg x 2 days). Compared with controls, a significantly shortened time to achieve an absolute neutrophil (ANC) count over 500/microL was observed in animals receiving 2- and 7-day courses of rhIL-1b (17 v 30 days), while animals receiving a 14-day course of rhIL- 1b achieved an ANC over 500/microL by 23 days. Concomitantly, a marked increase in granulocyte-macrophage colonies (CFU-GM) was observed at 14 days following 5-FU in animals receiving 2- and 7-day rhIL-1b courses. In animals receiving a 14-day rhIL-1b course, a significant increase in CFU-GM relative to control was not seen until 21 days post 5-FU. Utilizing a serum-free colony assay system, a 50% inhibition of normal marrow CFU-GM growth was observed with the addition of sera obtained on day 9 post 5-FU from animals receiving rhIL-1b for 14 days. Sera obtained at any time from animals receiving 2- and 7-day rhIL-1b treatment did not show any growth inhibition. Addition of antibodies to TNFa to the coculture assay abrogated the CFU-GM growth inhibition. TNFa levels in sera with the inhibitory activity was relatively high (918 pg/mL). Our data indicate that rhIL-1b enhances hematopoietic recovery following 5-FU if administered for short periods of time (less than 7 days), whereas prolonged administration has a counterproductive effect that is due in part to the induction of TNFa production.

Description: We describe the effects of in vitro irradiation on the proliferative capacity and hematopoietic supportive function of human marrow stromal cells. To assess the effects on the proliferative capacity of stromal progenitors and differentiated fibroblasts, marrow cell suspensions and trypsin-dispersed marrow fibroblasts were treated with a single dose of gamma radiation at 100 rad/min. Fibroblastic progenitors (CFU-F) showed an exponential decrease in colony formation with increasing doses of irradiation, with a Do slightly higher than that of granulomonopoietic progenitors (CFU-GM); Do values for CFU-F and CFU-GM were 130 and 115, respectively. However, although the CFU-F survival curve exhibited a shoulder (n = 1.3), the CFU-GM curve did not (n = 1.0), indicating that only fibroblastic progenitors have the potential to repair irradiation- induced damage. Passaged marrow fibroblast colony-forming cells also showed a shouldered exponential survival curve with a Do of 110 and n value of 1.4. Marrow stromal progenitors giving rise to adherent layers in long-term marrow cultures also demonstrated a highly radiosensitive proliferative capacity. Stromal layers derived from irradiated marrow suspensions failed to establish adherent layers after relatively low doses of irradiation (over 240 rad) in a dose-response manner. To assess any functional damage in stromal progenitors surviving irradiation, stromal layers derived from marrow suspensions irradiated up to 240 rad were cocultured with freshly isolated autologous hematopoietic cells and assayed for their capacity to support prolonged CFU-GM production. Confluent stromal layers derived from irradiated marrow suspensions sustained CFU-GM production as well as controls. To study the effects of irradiation on the hematopoietic supportive capacity of established marrow-derived stromal layers, 4 to 6-week-old adherent layers were irradiated as described and cocultured with autologous marrow cells enriched for colony-forming cells. Stromal layers irradiated up to 1,320 rad sustained prolonged CFU-GM production, indicating that the hematopoietic supportive function remained intact at this dose of irradiation. In conclusion, we demonstrated that the proliferative capacity of human marrow stromal progenitors, as well as that of their differentiated descendants, is quite sensitive to in vitro radiation, while the hematopoietic supportive function of differentiated stromal cells is relatively resistant to the effects of radiation.