The bed nucleus of the stria terminalis (BNST) is known to play a critical role in mediating the behavioural and autonomic responses to stressors. The oval nucleus of the BNST (BNSTov) contains cell bodies that synthesise the stress hormone corticotropin-releasing factor (CRF). Although afferent fibres originating from the BNSTov have been shown to innervate several key structures of the neuroendocrine and central autonomic system, the question remains as to whether some of these fibres are CRF-positive. To directly address this question, we injected a 'floxed' anterograde tracer (rAAV5/EF1a-DIO-mCherry) into the BNSTov of CRFp3.0CreGFP transgenic mice, which express a green fluorescent protein (GFP) under the control of the CRF promoter. Serial sections were then analysed for the presence of double-labelled fibres in potential projection sites. To determine whether CRF neurons in the rat BNSTov send comparable projections, we infused rat BNSTov with an adeno-associated viral vector (AAV) in which the human synapsin promoter drives enhanced GFP expression. We then used CRF immunoreactivity to examine double-labelled fluorescent fibres and axon terminals in projection sites from brain sections of the AAV-infused rats. We have observed several terminal fields in the mouse and rat brain with double-labelled fibres in the Dorsal raphe nucleus (DRD), the paraventricular nucleus of the hypothalamus and, to a lesser extent, in the ventral tegmental area. We found double-labelled terminal boutons in the nucleus accumbens shell, prelimbic cortex and posterior basolateral nucleus of the amygdala. The most intense double-labelling was found in midbrain, including substantia nigra pars compacta, red nucleus, periaqueductal grey and pontine nuclei, as well as DRD. The results of the present study indicate that CRF neurons are the output neurons of the BNSTov and they send projections not only to the centres of neuroendocrine and autonomic regulation, but also regions modulating reward and motivation, vigilance and motor function, as well as affective behaviour.
Cotranslational degradation of polypeptide nascent chains plays a critical role in quality control of protein synthesis and the rescue of stalled ribosomes. In eukaryotes, ribosome stalling triggers release of 60S subunits with attached nascent polypeptides, which undergo ubiquitination by the E3 ligase Ltn1 and proteasomal degradation facilitated by the ATPase Cdc48. However, the identity of factors acting upstream in this process is less clear. Here, we examined how the canonical release factors Sup45-Sup35 (eRF1-eRF3) and their paralogs Dom34-Hbs1 affect the total population of ubiquitinated nascent chains associated with yeast ribosomes. We found that the availability of the functional release factor complex Sup45-Sup35 strongly influences the amount of ubiquitinated polypeptides associated with 60S ribosomal subunits, while Dom34-Hbs1 generate 60S-associated peptidyl-tRNAs that constitute a relatively minor fraction of Ltn1 substrates. These results uncover two separate pathways that target nascent polypeptides for Ltn1-Cdc48-mediated degradation and suggest that in addition to canonical termination on stop codons, eukaryotic release factors contribute to cotranslational protein quality control.
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Juan A. Contreras-Vite;
Silvia Cruz-Rangel;
José J. De Jesus-Perez;
Iván A. Arechiga Figueroa;
Aldo A. Rodriguez-Menchaca;
Patricia Perez-Cornejo;
Harrison Hartzell Jr.;
Jorge Arreola
TMEM16A (ANO1), the pore-forming subunit of calcium-activated chloride channels, regulates several physiological and pathophysiological processes such as smooth muscle contraction, cardiac and neuronal excitability, salivary secretion, tumour growth and cancer progression. Gating of TMEM16A is complex because it involves the interplay between increases in intracellular calcium concentration ([Ca 2+ ] i ), membrane depolarization, extracellular Cl − or permeant anions and intracellular protons. Our goal here was to understand how these variables regulate TMEM16A gating and to explain four observations. (a) TMEM16A is activated by voltage in the absence of intracellular Ca 2+ . (b) The Cl − conductance is decreased after reducing extracellular Cl − concentration ([Cl − ] o ). (c) I Cl is regulated by physiological concentrations of [Cl − ] o . (d) In cells dialyzed with 0.2 μM [Ca 2+ ] i , Cl − has a bimodal effect: at [Cl − ] o < 30 mM TMEM16A current activates with a monoexponential time course, but above 30 mM, [Cl − ] o I Cl activation displays fast and slow kinetics. To explain the contribution of V m , Ca 2+ and Cl − to gating, we developed a 12-state Markov chain model. This model explains TMEM16A activation as a sequential, direct, and V m -dependent binding of two Ca 2+ ions coupled to a V m -dependent binding of an external Cl − ion, with V m -dependent transitions between states. Our model predicts that extracellular Cl − does not alter the apparent Ca 2+ affinity of TMEM16A, which we corroborated experimentally. Rather, extracellular Cl − acts by stabilizing the open configuration induced by Ca 2+ and by contributing to the V m dependence of activation.
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Mark C. Walters;
Laura M. De Castro;
Keith M. Sullivan;
Lakshmanan Krishnamurti;
Naynesh Kamani;
Christopher Bredeson;
Donna Neuberg;
Kathryn L. Hassell;
Stephanie Farnia;
Andrew Campbell;
Effie Petersdorf
Although a number of published trials exist of HLA-identical sibling hematopoietic cell transplantation (HCT) for sickle cell disease (SCD) that span 2 decades, when and for whom this therapy should be pursued is a subject of debate. Assessments of the risks of transplant-related complications that include infertility and debilitating graft-versus-host disease and long-term quality of life after successful HCT are difficult to perform without prospective trials in transplant and nontransplant cohorts. However, it is possible to assess the risk of mortality and to compare published rates of survival in individuals with SCD treated and not treated by HCT. In this brief review, projections about mortality risk based on recent published reports are reviewed and summarized. The published data show overall survival and event-free survival rates of 95% and 92%, respectively, in children treated by HLA-identical sibling HCT. The overall survival rates in the Center for International Blood and Marrow Transplant Research (N = 412) and European Blood and Marrow Transplant (N = 487) registries were 91% and 95%, respectively. These results provide broad support for the therapeutic value of HLA-identical sibling HCT for children with SCD and serve as the basis for a strong recommendation in favor of the option of HCT when a suitable donor is available. The experience of HLA-identical sibling HCT in adults with SCD is limited but appears to be similar to results in children. These preliminary observations, however, warrant further investigation.
The environmental factors that lead to the reactivation of human T cell leukemia virus type-1 (HTLV-I) in latently infected T cells in vivo remain unknown. It has been previously shown that heat shock (HS) is a potent inducer of HTLV-I viral protein expression in long-term cultured cell lines. However, the precise HTLV-I protein(s) and mechanisms by which HS induces its effect remain ill-defined. We initiated these studies by first monitoring the levels of the trans-activator (Tax) protein induced by exposure of the HTLV-I infected cell line to HS. HS treatment at 43 °C for 30 min for 24 h led to marked increases in the level of Tax antigen expression in all HTLV-I-infected T cell lines tested including a number of HTLV-I-naturally infected T cell lines. HS also increased the expression of functional HTLV-I envelope gp46 antigen, as shown by increased syncytium formation activity. Interestingly, the enhancing effect of HS was partially inhibited by the addition of the heat shock protein 70 (HSP70)-inhibitor pifithlin-µ (PFT). In contrast, the HSP 70-inducer zerumbone (ZER) enhanced Tax expression in the absence of HS. These data suggest that HSP 70 is at least partially involved in HS-mediated stimulation of Tax expression. As expected, HS resulted in enhanced expression of the Tax-inducible host antigens, such as CD83 and OX40. Finally, we confirmed that HS enhanced the levels of Tax and gp46 antigen expression in primary human CD4+ T cells isolated from HTLV-I-infected humanized NOD/SCID/γc null (NOG) mice and HTLV-I carriers. In summary, the data presented herein indicate that HS is one of the environmental factors involved in the reactivation of HTLV-I in vivo via enhanced Tax expression, which may favor HTLV-I expansion in vivo.
We developed quantitative assays to test the hypothesis that the N-DRC is required for integrity of the ciliary axoneme. We examined reactivated motility of demembranated drc cells, commonly termed “reactivated cell models.” ATP-induced reactivation of wild-type cells resulted in the forward swimming of ∼90% of cell models. ATP-induced reactivation failed in a subset of drc cell models, despite forward motility in live drc cells. Dark-field light microscopic observations of drc cell models revealed various degrees of axonemal splaying. In contrast, >98% of axonemes from wild-type reactivated cell models remained intact. The sup-pf4 and drc3 mutants, unlike other drc mutants, retain most of the N-DRC linker that interconnects outer doublet microtubules. Reactivated sup-pf4 and drc3 cell models displayed nearly wild-type levels of forward motility. Thus, the N-DRC linker is required for axonemal integrity. We also examined reactivated motility and axoneme integrity in mutants defective in tubulin polyglutamylation. ATP-induced reactivation resulted in forward swimming of >75% of tpg cell models. Analysis of double mutants defective in tubulin polyglutamylation and different regions of the N-DRC indicate B-tubule polyglutamylation and the distal lobe of the linker region are both important for axonemal integrity and normal N-DRC function.
Bone metastasis is a major cause of prostate cancer (PCa) morbidity and mortality. Despite some success in transiently controlling clinical symptoms with docetaxel-based therapy, PCa patients become docetaxel-resistant and inevitably progress with no cure. We synthesized an acyl-tyrosine bisphosphonate amide derivative, BKM1644, with the intent of targeting bone metastatic PCa and enhancing docetaxel's efficacy. BKM1644 exhibits potent anti-cancer activity in the NCI-60 panel and effectively inhibits the proliferation of metastatic, castration-resistant PCa (mCRPC) cells, with IC50 ranging between 2.1 μM and 6.3 μM. Significantly, BKM1644 sensitizes mCRPC cells to docetaxel treatment. Mice with pre-established C4-2 tumors in the tibia show a marked decrease in serum prostate-specific antigen (control: 173.72 ± 37.52 ng/ml, combined treatment: 64.45 ± 22.19 ng/ml; p < 0.0001) and much improved bone architecture after treatment with the combined regimen. Mechanistic studies found that docetaxel temporarily but significantly increases survivin, an anti-apoptotic protein whose overexpression has been correlated with PCa bone metastasis and therapeutic resistance. Intriguingly, BKM1644 effectively inhibits survivin expression, which may antagonize docetaxel-induced survivin in bone metastatic PCa cells. Signal transducer and activator of transcription 3 (Stat3) may be involved in the suppression of survivin transcription by BKM1644, as confirmed by a survivin reporter assay. Collectively, these data indicate that BKM1644 could be a promising small-molecule agent to improve docetaxel efficacy and retard the bone metastatic growth of PCa.
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Reinhold Munker;
Ruta Brazauskas;
Hai Lin Wang;
Marcos de Lima;
Hanna Khoury;
Robert Gale;
Richard Maziarz;
Brenda Sandmaier;
Daniel Weisdorf;
Wael Saber
Acute biphenotypic leukemias or mixed phenotype acute leukemias (MPAL) are rare and considered high risk. The optimal treatment and the role of allogeneic hematopoietic stem cell transplantation (alloHCT) are unclear. Most prior case series include only modest numbers of patients who underwent transplantation. We analyzed the outcome of 95 carefully characterized alloHCT patients with MPAL reported to the Center for International Blood and Marrow Transplant Research between 1996 and 2012. The median age was 20 years (range, 1 to 68). Among the 95 patients, 78 were in first complete remission (CR1) and 17 were in second complete remission (CR2). Three-year overall survival (OS) of 67% (95% confidence interval [CI], 57 to 76), leukemia-free survival of 56% (95% CI, 46 to 66), relapse incidence of 29% (95% CI, 20 to 38), and nonrelapse mortality of 15% (95% CI, 9 to 23) were encouraging. OS was best in younger patients (<20 years), but no significant differences were observed between those 20 to 40 years of age and those who were 40 years or older. A matched-pair analysis showed similar outcomes comparing MPAL cases to 375 acute myelogenous leukemia or 359 acute lymphoblastic leukemia cases. MPAL patients had more acute and a trend for more chronic graft-versus-host disease. No difference was observed between patients who underwent transplantation in CR1 versus those who underwent transplantation in CR2. AlloHCT is a promising treatment option for pediatric and adult patients with MPAL with encouraging long-term survival.
Pluripotent stem cell aggregates offer an attractive approach to emulate embryonic morphogenesis and skeletal development. Calcium phosphate (CaP) based biomaterials have been shown to promote bone healing due to their osteoconductive and potential osteoinductive properties. In this study, we hypothesized that incorporation of CaP-coated hydroxyapatite mineral particles (MPs) within murine embryonic stem cell (ESC) aggregates could promote osteo-chondrogenic differentiation. Our results demonstrated that MP alone dose-dependently promoted the gene expression of chondrogenic and early osteogenic markers. In combination with soluble osteoinductive cues, MPs enhanced the hypertrophic and osteogenic phenotype, and mineralization of ESC aggregates. Additionally, MPs dose-dependently reduced ESC pluripotency and thereby decreased the size of teratomas derived from MP-incorporated ESC aggregates in vivo.
Our data suggested a novel yet simple means of using mineral particles to control stem cell fate and create an osteochondral niche for skeletal tissue engineering applications. Statement of Significance Directing stem cell differentiation and morphogenesis via biomaterials represents a novel strategy to promote cell fates and tissue formation. Our study demonstrates the ability of calcium phosphate-based mineral particles to promote osteochondrogenic differentiation of embryonic stem cell aggregates as well as modulate teratoma formation in vivo. This hybrid biomaterial-ESC aggregate approach serves as an enabling platform to evaluate the ability of biomaterials to regulate stem cell fate and regenerate functional skeletal tissues for clinical applications.
Fragile X mental retardation protein (FMRP) is a multifunctional RNA-binding protein with crucial roles in neuronal development and function. Efforts aimed at elucidating how FMRP target mRNAs are selected have produced divergent sets of target mRNA and putative FMRP-bound motifs, and a clear understanding of FMRP's binding determinants has been lacking. To clarify FMRP's binding to its target mRNAs, we produced a shared dataset of FMRP consensus binding sequences (FCBS), which were reproducibly identified in two published FMRP CLIP sequencing datasets. This comparative dataset revealed that of the various sequence and structural motifs that have been proposed to specify FMRP binding, the short sequence motifs TGGA and GAC were corroborated, and a novel TAY motif was identified. In addition, the distribution of the FCBS set demonstrates that FMRP preferentially binds to the coding region of its targets but also revealed binding along 3′ UTRs in a subset of target mRNAs. Beyond probing these putative motifs, the FCBS dataset of reproducibly identified FMRP binding sites is a valuable tool for investigating FMRP targets and function.