TrkB agonist antibody pretreatment enhances neuronal survival and long-term sensory motor function following hypoxic ischemic injury in neonatal rats

Perinatal hypoxic ischemia (H-I) causes brain damage and long-term neurological impairments, leading to motor dysfunctions and cerebral palsy. Many studies have demonstrated that the TrkB-ERK1/2 signaling pathway plays a key role in mediating the protective effect of brain-derived neurotrophic factor (BDNF) following perinatal H-I brain injury in experimental animals. In the present study, we explored the neuroprotective effects of the TrkB-specific agonist monoclonal antibody 29D7 on H-I brain injury in neonatal rats. First, we found that intracerebroventricular (icv) administration of 29D7 in normal P7 rats markedly increased the levels of phosphorylated ERK1/2 and phosphorylated AKT in neurons up to 24 h. Second, P7 rats received icv administration of 29D7 and subjected to H-I injury induced by unilateral carotid artery ligation and exposure to hypoxia (8% oxygen). We found that 29D7, to a similar extent to BDNF, significantly inhibited activation of caspase-3, a biochemical hallmark of apoptosis, following H-I injury. Third, we found that this 29D7-mediated neuroprotective action persisted at least up to 5 weeks post-H-I injury as assessed by brain tissue loss, implicating long-term neurotrophic effects rather than an acute delay of cell death. Moreover, the long-term neuroprotective effect of 29D7 was tightly correlated with sensorimotor functional recovery as assessed by a tape-removal test, while 29D7 did not significantly improve rotarod performance. Taken together, these findings demonstrate that pretreatment with the TrkB-selective agonist 29D7 significantly increases neuronal survival and behavioral recovery following neonatal hypoxic-ischemic brain injury

Cross-Regulation between Oncogenic BRAFV600E Kinase and the MST1 Pathway in Papillary Thyroid Carcinoma

BACKGROUND:The BRAF(V600E) mutation leading to constitutive signaling of MEK-ERK pathways causes papillary thyroid cancer (PTC). Ras association domain family 1A (RASSF1A), which is an important regulator of MST1 tumor suppressor pathways, is inactivated by hypermethylation of its promoter region in 20 to 32% of PTC. However, in PTC without RASSF1A methylation, the regulatory mechanisms of RASSF1A-MST1 pathways remain to be elucidated, and the functional cooperation or cross regulation between BRAF(V600E) and MST1,which activates Foxo3,has not been investigated. METHODOLOGY/PRINCIPAL FINDINGS:The negative regulators of the cell cycle, p21 and p27, are strongly induced by transcriptional activation of FoxO3 in BRAF(V600E) positive thyroid cancer cells. The FoxO3 transactivation is augmented by RASSF1A and the MST1 signaling pathway. Interestingly, introduction of BRAF(V600E)markedly abolished FoxO3 transactivation and resulted in the suppression of p21 and p27 expression. The suppression of FoxO3 transactivation by BRAF(V600E)is strongly increased by coexpression of MST1 but it is not observed in the cells in which MST1, but not MST2,is silenced. Mechanistically, BRAF(V600E)was able to bind to the C-terminal region of MST1 and resulted in the suppression of MST1 kinase activities. The induction of the G1-checkpoint CDK inhibitors, p21 and p27,by the RASSF1A-MST1-FoxO3 pathway facilitates cellular apoptosis, whereas addition of BRAF(V600E) inhibits the apoptotic processes through the inactivation of MST1. Transgenic induction of BRAF(V600E)in the thyroid gland results in cancers resembling human papillary thyroid cancers. The development of BRAF(V600E)transgenic mice with the MST1 knockout background showed that these mice had abundant foci of poorly differentiated carcinomas and large areas without follicular architecture or colloid formation. CONCLUSIONS/SIGNIFICANCE:The results of this study revealed that the oncogenic effect of BRAF(V600E) is associated with the inhibition of MST1 tumor suppressor pathways, and that the activity of RASSF1A-MST1-FoxO3 pathways determines the phenotypes of BRAF(V600E) tumors

Structure of the [beta] subunit of translation initiation factor 2 from the Archaeon Methanococcus jannaschii by NMR : a representative of the eIF2[beta]/eIF5 family of proteins

texteIF2b is one of the three subunits of eukaryotic initiation factor 2 (eIF2), a protein which recruits the initiator Met-tRNA and GTP to the 40S ribosomal subunit as part of the 43S pre-initiation complex. The three dimensional structure of aIF2b from Methanococcus jannaschii, an archaeal homologue of eIF2, was determined using multidimensional NMR methods. The aIF2b was found to consist of two independent structural domains. The N-terminal domain contains a four-stranded antiparallel b sheet and two a helices on one side of the sheet. The folding topology was found to be similar to that of the DNA-binding domain of a yeast heat shock transcription factor and a domain within the ribosomal protein S4, although there is no significant homology at the level of primary sequence. The C-terminal domain of aIF2b contains a 'zinc ribbon' motif of three antiparallel b strands, with four conserved cysteines arranged as two CXXC units separated by 17 residues. The role of zinc in the C-terminal domain was investigated with a synthetic peptide that corresponds to the last 50 amino acid residues (residues 94-143) of aIF2b. The N- and Cterminal domains of aIF2b are connected by a helical linker, and were found to be independent of each other. Conserved residues on the surface of each domain that are likely candidates for direct interaction with other components of the translational apparatus were identified. The significant primary sequence homology between archaeal aIF2b and the eukaryotic initiation factors eIF2b and eIF5 allows structural features to be predicted for these latter two proteins from this first structural model of aIF2b.Pharmac

Neurotrophic Effect of a Novel TrkB Agonist on Retinal Ganglion Cells

The authors demonstrated that TrkB monoclonal antibody strongly promotes postnatal retinal ganglion cell (RGC) survival and neurite growth in vitro as well as injured adult RGCs in vivo. In addition, they demonstrated the potential for antibody-mediated TrkB agonism as a potential therapeutic approach for RGCs

Low-Power Small-Area Inverter-Based DSM for MEMS Microphone

A delta-sigma modulator (DSM) is proposed for the direct connection to micro-electro-mechanical systems (MEMS) microphone. To reduce power, both the DAC reference voltage (VREF) and the DSM supply voltage (VDD) are reduced to 700 mV by limiting the maximum linear acoustic input range to 110 dB SPL (sound pressure level). For the low VDD operation, the switched capacitor (SC) integrators of DSM employ CMOS inverters as amplifiers. A unity-gain buffer compensates the pole error of the SC integrator; it reduces chip area by replacing the auto-zero capacitor of conventional inverter-based SC integrator. Compared to the conventional integrator, the integrator of this brief reduces the pole error from 0.3x0025; to 0.06x0025;, reduces the chip area and the power by 32.4x0025; and 24.8x0025;, respectively. The 3(rd) order DSM in a 65 nm CMOS process was measured to have Walden-figure of merit (FoMw) 89.3fJ/step, dynamic range (DR) 90.1 dB, signal-to-noise ratio (SNR) 87.2 dB, signal-to-noise and distortion ratio (SNDR) 86.4 dB, and power 122 uW at 10 MHz clock frequency (Fs).11Nsciescopu