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PubMed1985

Role of N-acetyl-D-galactosamine residue on B151K12-derived T cell-replacing factor (B151-TRF) molecule in B cell-receptor binding and -stimulating activity.

The role of sugar moiety on T cell-replacing factor molecule derived from a monoclonal T cell hybridoma B151K12 (B151-TRF) was analyzed with respect to the interaction with receptor on B cells. The induction of B cell differentiation into Ig-secreting cells by B151-TRF was specifically inhibited by addition of N-acetyl-D-galactosamine (GalNAc) to culture. Such inhibition appeared to be attributed to the interference of GalNAc in the interaction of TRF with its receptor, because absorption of TRF activity with B cells was notably inhibited by the presence of GalNAc. To substantiate this point further, we established binding assay of B151-TRF molecule to the receptor on B cells by using 125I-labeled TRF fraction enriched by reversed-phase high-performance liquid chromatography and gel filtration. The results revealed that the binding of 125I-TRF molecule to the B cells was almost completely blocked by GalNAc. Moreover, the existence of GalNAc residue(s) on B151-TRF molecule was evidenced by the facts that 1) the TRF activity was eluted from lectin gels with specificity for GalNAc as revealed by the functional assay, and 2) the 125I-TRF molecule specifically bound to such lectin gels. Thus, the GalNAc residue(s) on B151-TRF molecule plays an important role in binding of TRF molecule to the receptor and in the stimulation of B cells. The molecular properties of B cell-stimulatory B151-TRF and its mode of interaction with corresponding receptor on B cells were discussed in the context of B151-TRF as a glycosylated lymphokine molecule and B151-TRF receptor as a carbohydrate-binding protein (animal lectin).

Absorption↗
PubMed2026

tRF-3021a, a tRNA-Ala-TGC derived 3' fragment, promotes glioblastoma cell invasion, suppresses apoptosis, and is required for normal levels of protein synthesis.

UNLABELLED: tRNA-derived fragments (tRFs) are relatively recently discovered class of small RNAs implicated in gene-regulatory processes in diverse biological contexts but there have been very few reports of a clear phenotypic role of these small RNAs in cancer progression. By analyzing small RNA-seq data from The Cancer Genome Atlas (TCGA), we found that high expression of three 3' tRFs (tRF-3a), tRF-3009a, tRF-3021a or tRF-3030a, is significantly associated with poor overall survival in low-grade glioma (LGG). In glioblastoma cells, tRF-3009a, tRF-3021a and tRF-3030a enhance cell invasion and migration but tRF-3021a was uniquely required for cell proliferation and suppression of apoptosis. Interestingly, tRF-3021a knockdown decreases global protein synthesis prior to and independent of apoptosis. These data indicate that tRF-3021a supports glioma cell survival and particularly protein synthesis while promoting cellular invasion and migration. Given its association with poor outcome in LGG patients, tRF-3021a represents a promising biomarker and potential therapeutic target in gliomas and these results provide a foundation for future studies to define its molecular interactors and downstream pathways controlling protein synthesis and apoptosis in cancer cells. IMPLICATION: tRF-3021a promotes malignant glioma phenotypes, sustains global protein synthesis and prevents spontaneous apoptosis, motivating efforts to evaluate it as a biomarker and therapeutic target.

Journal Article↗
PubMed1986

Evidence for existence of two distinct TNP-Ficoll-responsive B cell subpopulations preferentially reactive either to a T cell-replacing factor (B151-TRF) or to a signal from accessory cells.

The ability of B cells to respond to TNP-Ficoll has been shown to correlate with their ability to respond to T cell-replacing factor (TRF). The present study analyzed the relationship of TNP-Ficoll-responsive B cells to a TRF-responsive B cell subpopulation. The B cells from normal, unprimed mice responded to TNP-Ficoll in the presence of accessory cells. Such responses were notably augmented by the addition of TRF derived from a monoclonal T cell hybridoma, B151K12(B151-TRF). Interestingly, B cells of mutant X-linked immunodeficient DBA/2Ha which failed to respond to B151-TRF gave anti-TNP PFC responses to TNP-Ficoll comparable to those of normal mice, depending on the presence of accessory cells. However, under this condition, the addition of B151-TRF did not augment the TNP-Ficoll responses. One explanation of the augmentation of TNP-Ficoll response by TRF for the B cells from nondefective mice was that two distinct B cell subpopulations exist which differ in their respective activation requirement for TRF and accessory cells. To examine this possibility, syngeneic accessory cells were pulsed with TNP-Ficoll and were assayed for their ability to activate normal B cells in the presence or absence of B151-TRF. The results revealed that TNP-Ficoll-pulsed accessory cells were able to induce primary anti-TNP PFC responses in normal B cells to the same magnitude as soluble TNP-Ficoll. However, these B cell responses induced by the TNP-Ficoll-pulsed accessory cells were not augmented by the addition of B151-TRF to the culture. These results support the notion that two distinct TNP-Ficoll-responsive B cell subpopulations exist; one requires accessory cell-B cell interaction to be activated by TNP-Ficoll but fails to respond to TRF, and the other can be activated by TRF in a totally accessory cell-independent manner.

Animals↗
PubMed1985

Purification and physicochemical characterization of murine T cell replacing factor (TRF).

Murine T cell replacing factor (TRF) was purified from a cellfree supernatant of a T cell hybridoma (B151K12) that constitutively produces TRF. Two assay systems for TRF activity were employed: 1) induction of anti-DNP IgG PFC responses in cultures of splenic B cells from DNP-KLH-primed BALB/c mice, and 2) induction of IgM PFC in chronic B cell leukemic cells (BCL1). The purification scheme consisted of ammonium sulfate precipitation, DEAE-cellulose chromatography, Blue-Sepharose chromatography, hydroxylapatite chromatography, gel permeation with fast protein liquid chromatography (FPLC), and disc polyacrylamide gel electrophoresis. Overall, TRF was purified approximately 34,000-fold with a maximum 3.8% recovery of activity, and the specific activity of the purified TRF was approximately 9.6 X 10(4) U/mg. The TRF that is active in these systems is distinct from the other lymphokines such as IL 1, IL 2, BCGFI (now known as BSFp1), and gamma-interferon. The TRF is extremely hydrophobic, with an apparent m.w. of 50,000 to 60,000 on gel permeation chromatography and 18,000 on SDS-PAGE under reducing conditions. Highly purified B151-TRF abrogated the activity by treatment with trypsin but not with RNase. Moreover, it bound to lima bean agglutinin-Sepharose specific for N-acetylgalactosamine residues, indicating that B151-TRF is a glycosylated glycoprotein containing N-acetylgalactosamine residues. The role of N-acetylgalactosamine residues on TRF activity was additionally substantiated by the fact that the addition of appropriate amounts of N-acetylgalactosamine in the assay systems for TRF preferentially induced a profound suppression for TRF-mediated PFC responses.

Adjuvants, Immunologic↗
PubMed1985

BCGFII activity on activated B cells of a purified murine T cell-replacing factor (TRF) from a T cell hybridoma (B151K12).

Experiments were performed to examine a growth-promoting activity on B cells or B leukemic cells of T cell-replacing factor (TRF) produced by a murine T cell hybridoma (B151K12) which constitutively produces TRF. The cellfree supernatant (CFS) from B151K12 cells (B151-CFS) could induce terminal differentiation of pre-activated B cells or in vivo passaged chronic B leukemia cells, BCL1, into immunoglobulin-secreting cells, while it did not exert a nominal lymphokine activity such as BCGFI (now known as BSFpl), IL 2, or gamma-interferon. However, it promoted [3H]thymidine uptake of dextran sulfate (DXS)-stimulated normal B cells and in vivo passaged BCL1 cells, suggesting that it also has BCGFII activity. We tried extensively to purify and to separate the TRF active molecule from the BCGFII active molecule by using many types of purification procedures. The purification scheme consisted of ammonium sulfate precipitation, DEAE-cellulose chromatography, Blue-Sepharose chromatography, hydroxylapatite chromatography, and gel permeation with fast protein liquid chromatography (FPLC). It was revealed that the BCGFII active molecule was hardly separable from the TRF during the entire purification procedure. The TRF as well as BCGFII active materials were glycoprotein with an apparent m.w. of 50 to 60 Kd on gel permeation chromatography and 18 Kd on SDS-PAGE under reducing conditions. The BCGFII active materials were hardly separable from the TRF active one, even after a reverse-phase FPLC, in which both BCGFII and TRF activities were recovered in the fractions eluted at 44 to 48% acetonitrile in 0.1% trifluoroacetic acid (TFA). Furthermore, the absorption of TRF and BCGFII active materials by using BCL1 cells removed not only TRF but also BCGFII activity. Moreover, B cell-specific monoclonal antibody (9T1), which can preferentially block TRF-dependent plaque-forming cell responses, also inhibited the expression of BCGFII activity to BCL1 cells. Taking all of the results together, we conclude that the TRF from B151K12 cells promotes growth of appropriately activated, such as DXS-stimulated normal cells and BCL1 tumor cells. These results suggest that B151-TRF may act on B cells as B cell growth and differentiation factors.

Absorption↗
PubMed1981

Presence of TRF immunoreactivity in marginal islet cells in rat pancreas.

Isolated rat pancreatic islet extracts were submitted to reverse phase high pressure chromatography (HPLC) and assayed for thyrotrophin releasing factor (TRF), glucagon and insulin in radioimmunoassays (RIA). Our anti-TRF serum was prepared by immunizing rabbits with TRF conjugated to bovine thyroglobulin (bTG) by bisdiazobenzidine. Anti-glucagon and antiinsulin were from a commercial source (Novo, Denmark). The concentrations of TRF, glucagon and insulin were 0.05 +/- 0.02, 0.06 +/- 0.02 and 1.0 +/- 0.2 pmol/islet, respectively. Formalin-fixed pancreatic sections were stained for TRF, glucagon and insulin by peroxidase, antiperoxidase (PAP) complex method. When the adjacent sections were stained for glucagon or insulin, it was observed that TRF and glucagon-specific peroxidase reactions were confined to the marginal islet cells, but insulin reactions to the central cells. The TRF-specific peroxidase reaction was clearly reduced when the anti-TRF serum was unchanged when the antiserum was pre-incubated with synthetic TRF. The present HPLC results suggest that the islets contained TRF. Immunocytochemical studies show that the TRF-immunoreactive material, either synthesized or bound, is localized in the marginal islet cells.

Animals↗
PubMed2003

Variation between observed and true Terminal Restriction Fragment length is dependent on true TRF length and purine content.

Terminal Restriction Fragment (TRF) pattern analysis has become a widely used and informative tool for studying microbial communities. Variation between sequence-determined or true TRF length and observed TRF length (TRF drift) has been previously reported and can significantly affect identification of bacterial species using TRF lengths predicted from sequence databases. In this study TRF drift was determined for 21 bacterial species using an ABI 310 Genetic Analyzer. TRF drift was positively correlated with true TRF length and negatively correlated with TRF purine content. This implies that subtle differences in molecular weight, whether from purine content or dye label, can significantly affect the observed TRF length.

Bacteria↗
PubMed1988

T cell-replacing factor (TRF)/interleukin 5 (IL-5): molecular and functional properties.

TRF has originally been defined as a T-cell-derived lymphokine that triggers activated B cells for a terminal differentiation into Ig-secreting cells. HPLC-purified TRF from Sup of a murine TRF-producing B151 cell is an acidic glycoprotein, exerts BCGF II activity and induces expression of IL-2 receptors. It does not show IL-1, IL-2, IL-3, BSF-1/IL-4, or IFN gamma activity. We prepared monoclonal TB13 and NC17 antibodies against HPLC-purified B151-TRF which are specific for and can inhibit TRF as well as BCFG II activity of B151-TRF. Moreover, TB13 as well as NC17 antibody can immunoprecipitate the 46 Kd molecule from B151 Sup which exerts TRF as well as BCGF II activity. Complementary DNA (pSP6K-mTRF23) encoding for murine TRF/IL-5 was cloned and its entire nucleotide sequences were determined. The murine TRF/IL-5 cDNA encodes 133 amino acids including N-terminal strongly hydrophobic regions. Secreted recombinant TRF/IL-5 (apparent m.w. of 46 Kd) has 113 amino acid residues and also comprises homodimers of a molecule with an apparent m.w. of 25 to 30 Kd. TRF/IL-5 mRNA is constitutively expressed in constitutively TRF-producing B151 and is inducible in some T cell lines upon stimulation with PMA or Con A. TRF/IL-5 mRNA is also expressed in Tbc-primed T cells upon the stimulation with PPD, whereas its expression is not effectively induced in non-primed spleen cells by stimulation with Con A or PMA plus calcium ionophore. The translation product of murine TRF/IL-5 cDNA triggers resting as well as activated (DNP-primed or LPS-stimulated) murine B cells for terminal differentiation into Ig-secreting cells (IgM, IgG1, or IgA) accompanied by increased mRNA expression for secreted forms of relevant Ig heavy chain (mu, gamma, or alpha). Among these, increases in the level of mu, and alpha-specific mRNA for the secreted form of IgM and IgA, respectively, are prominent. Moreover, TRF/IL-5 induces maturation of resting B cells into IgM-secreting cells. TRF/IL-5 promotes growth of activated B cells as well as BCL1 cells. TRF/IL-5 is, therefore, a growth as well as a differentiation inducing factor for B cells. Moreover, it induces functional IL-2 receptors on resting as well as activated B cells, besides TRF and BCGF II activities.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1987

Role of T cell-replacing factor (TRF) in the murine B cell differentiation: induction of increased levels of expression of secreted type IgM mRNA.

T cell-replacing factor (TRF) is known to play a critical role in the regulation of B cell growth and differentiation. In this study, the role of TRF in the expression of mRNA for both IgM and IgG1 class was investigated. The TRF was purified from cellfree supernatants from a T cell hybridoma, B151K12. RNA was isolated from chronic B cell leukemia (BCL1) cells, DNP-KLH-primed B cells, or normal B cells cultured with or without LPS, and LPS plus TRF or LPS plus BSF-1. The steady state level of isotype-specific mRNA was assessed by Northern blot analysis with a mu-specific or a gamma 1-specific probe. It was demonstrated that BCL1 and purified B cells cocultured with TRF expresses increased levels (twofold and fourfold, respectively) of secreted forms of mu mRNA. Purified B cells from DNP-KLH-primed mice also expressed increased levels (twofold to fourfold) of mu as well as gamma 1 mRNA for secreted form by stimulation with TRF. Total expression of mu mRNA, however, was approximately threefold higher than that of gamma 1 mRNA. The stimulation of normal B cells with LPS plus TRF induced an increase in the levels of mu mRNA and gamma 1 mRNA expression, fourfold and threefold, respectively. However, the levels of gamma 1 mRNA expression was one-third of that induced in B cells stimulated with LPS plus BSF-1. These results indicate that TRF preferentially induces increased levels of secreted type of mu mRNA and induces less gamma 1 mRNA than BSF-1. The differential role of TRF from BSF-1 in the expression of Ig mRNA will be discussed.

Animals↗
PubMedDate not supplied

Intensification of central catecholaminergin and serotonergic processes by the hypothalamic factors MIF and TRF and by angiotensin II.

The present work deals with the action of MIF (melanocyte stimulating hormone release-inhibiting factor), TRF (thyrotropin releasing factor), and angiotensin II on the behavioral effects of L-DOPA and of D, L-5-hydroxytrytophan (5-HTP) in mice. The influence of MIF and TRF on the antagonistic effect of L-DOPA of harmine tremors in rabbits was also studied. MIF and TRF, injected i.p., intensify the effects of L-DOPA in mice. The minimal dose of MIF required to induce a +3 response is 0.1 microgram/kg; TRF is active at 500 micrograms/kg. When MIF or TRF are injected into the brain, potentiation of L-DOPA is obtained with exceedingly small quantities of MIF (0.1 pg); the effective dose of TRF is 1 microgram. The behavioral effects of 5-HTP are potentiated by TRF only, at doses of 0.1 microgram/kg, i.p. When TRF is administered intracerebrally, the active dose per mouse is 0.1 ng. Harmine (5 mg/kg i.v.) induced, in the rabbit, sustained whole body tremors; if L-DOPA (5 mg/kg) is administered i.v. at the peak of the harmine effect, tremors subside. When the rabbit is pretreated with MIF administered i.p. 1 -2 hr before harmine, in doses devoid of an antitumor effect per se (10 micrograms/kg), the L-DOPA antagonism appears at lower dose. Also dopamine (5-10 mg/kg i,v.) proved effective in abating harmine tremors; previous treatment with MIF (50 micrograms/kg) potentiated the antagonistic effect of dopamine. According to the prevailing theories on the mechanism of neurotransmission, some hypotheses will be discussed to explain the observed potentiation: impaired uptake, impaired degradation, interference with the turnover of the boiamines, supersensitivity of the receptors.

5-Hydroxytryptophan↗