Protease-Resistant Prions Selectively Decrease Shadoo Protein

The central event in prion diseases is the conformational conversion of the cellular prion protein (PrPC) into PrPSc, a partially protease-resistant and infectious conformer. However, the mechanism by which PrPSc causes neuronal dysfunction remains poorly understood. Levels of Shadoo (Sho), a protein that resembles the flexibly disordered N-terminal domain of PrPC, were found to be reduced in the brains of mice infected with the RML strain of prions [1], implying that Sho levels may reflect the presence of PrPSc in the brain. To test this hypothesis, we examined levels of Sho during prion infection using a variety of experimental systems. Sho protein levels were decreased in the brains of mice, hamsters, voles, and sheep infected with different natural and experimental prion strains. Furthermore, Sho levels were decreased in the brains of prion-infected, transgenic mice overexpressing Sho and in infected neuroblastoma cells. Time-course experiments revealed that Sho levels were inversely proportional to levels of protease-resistant PrPSc. Membrane anchoring and the N-terminal domain of PrP both influenced the inverse relationship between Sho and PrPSc. Although increased Sho levels had no discernible effect on prion replication in mice, we conclude that Sho is the first non-PrP marker specific for prion disease. Additional studies using this paradigm may provide insight into the cellular pathways and systems subverted by PrPSc during prion disease

Exacerbation of experimental autoimmune encephalomyelitis in prion protein (PrPc)-null mice: evidence for a critical role of the central nervous system

<p>Abstract</p> <p>Background</p> <p>The cellular prion protein (PrPc) is a host-encoded glycoprotein whose transconformation into PrP scrapie (PrPSc) initiates prion diseases. The role of PrPc in health is still obscure, but many candidate functions have been attributed to the protein, both in the immune and the nervous systems. Recent data show that experimental autoimmune encephalomyelitis (EAE) is worsened in mice lacking PrPc. Disease exacerbation has been attributed to T cells that would differentiate into more aggressive effectors when deprived of PrPc. However, alternative interpretations such as reduced resistance of neurons to autoimmune insult and exacerbated gliosis leading to neuronal deficits were not considered.</p> <p>Method</p> <p>To better discriminate the contribution of immune cells versus neural cells, reciprocal bone marrow chimeras with differential expression of PrPc in the lymphoid or in the central nervous system (CNS) were generated. Mice were subsequently challenged with MOG_35-55peptide and clinical disease as well as histopathology were compared in both groups. Furthermore, to test directly the T cell hypothesis, we compared the encephalitogenicity of adoptively transferred PrPc-deficient versus PrPc-sufficient, anti-MOG T cells.</p> <p>Results</p> <p>First, EAE exacerbation in PrPc-deficient mice was confirmed. Irradiation exacerbated EAE in all the chimeras and controls, but disease was more severe in mice with a PrPc-deleted CNS and a normal immune system than in the reciprocal construction. Moreover, there was no indication that anti-MOG responses were different in PrPc-sufficient and PrPc-deficient mice. Paradoxically, PrPc-deficient anti-MOG 2D2 T cells were less pathogenic than PrPc-expressing 2D2 T cells.</p> <p>Conclusions</p> <p>In view of the present data, it can be concluded that the origin of EAE exacerbation in PrPc-ablated mice resides in the absence of the prion protein in the CNS. Furthermore, the absence of PrPc on both neural and immune cells does not synergize for disease worsening. These conclusions highlight the critical role of PrPc in maintaining the integrity of the CNS in situations of stress, especially during a neuroinflammatory insult.</p

Protocol for augmented shoot organogenesis in selected variety of soybean [<i>Glycine</i><i style="mso-bidi-font-style: normal"> max</i> L. (Merr.)]

729-734<span style="mso-bidi-font-size:9.0pt;letter-spacing: -.1pt" lang="EN-GB">Development of a reproducible, versatile and efficient in vitro plant regeneration system is highly warranted for Indian soybean varieties for their mass multiplication in view of their commercial significance. Accordingly a protocol for direct shoot organogenesis in soybean variety JS 335 has been developed. Using cotyledonary node explants significant organogenic responses, mean shoot number and shoot length were observed when these were incubated on MS medium supplemented with 0.89 µM Benzyladenine (BA) and 5 <span style="mso-bidi-font-size:9.0pt;mso-fareast-font-family: TimesNewRoman;letter-spacing:-.1pt" lang="EN-GB">μ<span style="mso-bidi-font-size: 9.0pt;letter-spacing:-.1pt" lang="EN-GB">g/L triacontanol (TRIA) where in 9.3 ± 0.5 shoots were obtained. TRIA at 5 <span style="mso-bidi-font-size: 9.0pt;mso-fareast-font-family:TimesNewRoman;letter-spacing:-.1pt" lang="EN-GB">μg /L able to produce 6.8 ± 0.5 shoot buds in presence of 0.98 µ<i style="mso-bidi-font-style: normal">M IBA and 0.89 µM BA. Highest mean shoot buds (14.0 ± 0.5 and 9.0 ± 0.5) and mean shoot length (4.6 ± 0.3 and 10.0 ± 0.7) were obtained when cotyledonary node and shoot tip explants were cultured on MS medium containing 0.14 µM gibberellic acid (GA3), 0.89 µM BA and 5<span style="mso-bidi-font-size:9.0pt;mso-fareast-font-family: TimesNewRoman;letter-spacing:-.1pt" lang="EN-GB"> μ<span style="mso-bidi-font-size: 9.0pt;letter-spacing:-.1pt" lang="EN-GB">g/L TRIA. Moreover, TRIA supported highest mean root number (6.3±0.5) and root length (21.5 ± 0.57 cm). Field survival of in vitro derived plants of TRIA treatment was 70% and the overall growth and seed yield was also significantly better than control plants. This protocol may be used for improving the in vitro regeneration of soybean variety JS 335 for transformation studies. </span

Variation in in vitro Morphogenic Response to Growth Regulators in Soybean Genotypes from India and Bulgaria

Soybean (Glycinae max (L.) Merrill.) is receiving great global importance due to its nutraceutical value but its cultivation suffers the problems of biotic/abiotic stress. To improve soybean germplasm biotechnological approach can be applied. The objectives of the experiments were to study the possibilities for establishment of in vitro cultures which can be used for genetic manipulations and modelling of stress. In vitro morphogeneic response of two Indian (Hardee and JS 335), one Bulgarian (Daniela) and one american (Hodson) soybean cultivars were studied using plant growth regulators. Using cotyledonary nodes as explants, high organogenic response was observed for cv Daniela and cv Hodson on media containig BAP and IBA. TDZ induced multiple shoot buds in all the cultivars, with varying degree of response and it was found to be genotype specific. A maximum of 8 shoot buds were obtained from cotyledonary node explants in presence of TDZ (0.5 mg/l) for the cv. Hardee. A negative correlation was observed between bud number and size for the Bulgarian cultivars. The results indicate the stimulating effect of TDZ on organogenesis and the interaction of genotype and culture media, which can be utilized for crop improvement using tissue culture techniques

Metabolic control of adult neural stem cell self-renewal by the mitochondrial protease YME1L

The transition between quiescence and activation in neural stem and progenitor cells (NSPCs) is coupled with reversible changes in energy metabolism with key implications for lifelong NSPC self-renewal and neurogenesis. How this metabolic plasticity is ensured between NSPC activity states is unclear. We find that a state-specific rewiring of the mitochondrial proteome by the i-AAA peptidase YME1L is required to preserve NSPC self-renewal. YME1L controls the abundance of numerous mitochondrial substrates in quiescent NSPCs, and its deletion activates a differentiation program characterized by broad metabolic changes causing the irreversible shift away from a fatty-acid-oxidation-dependent state. Conditional Yme1l deletion in adult NSPCs in vivo results in defective self-renewal and premature differentiation, ultimately leading to NSPC pool depletion. Our results disclose an important role for YME1L in coordinating the switch between metabolic states of NSPCs and suggest that NSPC fate is regulated by compartmentalized changes in protein network dynamics