ER Stress Inhibits Liver Fatty Acid Oxidation while Unmitigated Stress Leads to Anorexia-Induced Lipolysis and Both Liver and Kidney Steatosis

The unfolded protein response (UPR), induced by endoplasmic reticulum (ER) stress, regulates the expression of factors that restore protein folding homeostasis. However, in the liver and kidney, ER stress also leads to lipid accumulation, accompanied at least in the liver by transcriptional suppression of metabolic genes. The mechanisms of this accumulation, including which pathways contribute to the phenotype in each organ, are unclear. We combined gene expression profiling, biochemical assays, and untargeted lipidomics to understand the basis of stress-dependent lipid accumulation, taking advantage of enhanced hepatic and renal steatosis in mice lacking the ER stress sensor ATF6α. We found that impaired fatty acid oxidation contributed to the early development of steatosis in the liver but not the kidney, while anorexia-induced lipolysis promoted late triglyceride and free fatty acid accumulation in both organs. These findings provide evidence for both direct and indirect regulation of peripheral metabolism by ER stress

Lack of NF1 expression in a sporadic schwannoma from a patient without neurofibromatosis

The neurofibromatosis type 1 (NF1) gene encodes a tumor suppressor protein, neurofibromin, which is expressed at high levels in Schwann cells and other adult tissues. Loss of NF1 expression has been reported in Schwann cell tumors (neurofibrosarcomas) from patients with NF1 and its loss is associated with increased proliferation of these cells. In this report, we describe downregulation of NF1 expression in a single spinal schwannoma from an individual without clinical features of neurofibromatosis type 1 or 2. Barely detectable expression of NF1 RNA was found in this tumor by in situ hybridization using an NF1 -specific riboprobe as well as by Northern blot and reverse-transcribed (RT)-PCR analysis. In Schwann cells cultured from this schwannoma, abundant expression of NF1 RNA could be detected by Northern blot and RT-PCR analysis. These results suggest that, in some tumors, expression of NF1 may be downregulated by factors produced within the tumor and may represent a novel mechanism for inactivating these growth suppressing genes and allowing for increased cell proliferation in tumors.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45383/1/11060_2005_Article_BF01057754.pd

Micromechanical Properties of Injection-Molded Starch–Wood Particle Composites

The micromechanical properties of injection molded starch–wood particle composites were investigated as a function of particle content and humidity conditions. The composite materials were characterized by scanning electron microscopy and X-ray diffraction methods. The microhardness of the composites was shown to increase notably with the concentration of the wood particles. In addition,creep behavior under the indenter and temperature dependence were evaluated in terms of the independent contribution of the starch matrix and the wood microparticles to the hardness value. The influence of drying time on the density and weight uptake of the injection-molded composites was highlighted. The results revealed the role of the mechanism of water evaporation, showing that the dependence of water uptake and temperature was greater for the starch–wood composites than for the pure starch sample. Experiments performed during the drying process at 70°C indicated that the wood in the starch composites did not prevent water loss from the samples.Peer reviewe

NGF effects on developing forebrain cholinergic neurons are regionally specific

Nerve growth factor (NGF) has been shown to have an effect on neurons in the central nervous system (CNS). A number of observations suggest that NGF acts as a trophic factor for cholinergic neurons of the basal forebrain and the caudate-putamen. We sought to further characterize the CNS actions of NGF by examining its effect on choline acetyltransferase (ChAT) activity in the cell bodies and fibers of developing neurons of the septum and caudate-putamen. ChAT activity was increased after even a single NGF injection. Interestingly, the magnitude of the effect of multiple NGF injections suggested that repeated treatments may augment NGF actions on these neurons. The time-course of the response to NGF was followed after a single injection on postnatal day (PD) 2. NGF treatment produced long-lasting increases in ChAT activity in septum, hippocampus and caudate-putamen. The response in cell body regions (septum, caudate-putamen) was characterized by an initial lag period of approximately 24 hr, a rapid rise to maximum values, a plateau phase and a return to baseline. The response in hippocampus was delayed by 48 hr relative to that in septum, indicating that NGF actions on ChAT were first registered in septal cell bodies. Finally, developmental events were shown to have a regionally specific influence on the response of neurons to NGF. For though the septal response to a single NGF injection was undiminished well into the third postnatal week, little or no response was detected in caudate-putamen at that time. In highlighting the potency and regional specificity of NGF effects, these observations provide additional, support for the hypothesis that NGF is a trophic factor for CNS cholinergic neurons.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45403/1/11064_2004_Article_BF00970927.pd

Nerve growth factor increases choline acetyltransferase activity in developing basal forebrain neurons

Nerve growth factor (NGF) is a neuronotrophic protein. Its effects on developing peripheral sensory and sympathetic neurons have been extensively characterized, but it is not clear whether NGF plays a role during the development of central nervous system neurons. To address this point, we examined the effect of NGF on the activity of neurotransmitter enzymes in several brain regions. Intracerebroventricular injections of highly purified mouse NGF had a marked effect on the activity of choline acetyltransferase (ChAT), a selective marker of cholinergic neurons. NGF elicited prominent increases in ChAT activity in the basal forebrain of neonatal rats, including the septum and a region which contains neurons of the nucleus basalis and substantia innominata. NGF also increased ChAT activity in the hippocampus and neocortex, terminal regions for the fibers of basal forebrain cholinergic neurons. In analogy with the response of developing peripheral neurons, the NGF effect was shown to be selective for basal forebrain cholinergic cells and to be dose-dependent. Furthermore, septal neurons closely resembled sympathetic neurons in the time course of their response to NGF. These observations suggest that endogenous NGF does play a role in the development of basal forebrain cholinergic neurons.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26109/1/0000185.pd

Brain delivery of biologics using a cross-species reactive transferrin receptor 1 VNAR shuttle.

Transferrin receptor 1 (TfR1) mediated transcytosis is an attractive strategy to enhance brain uptake of protein drugs, but translation remains a challenge. Here, a single domain shark antibody VNAR fragment (TXB2) with similar affinity to murine and human TfR1 was used to shuttle protein cargo into the brain. TXB2 was fused to a human IgG1 Fc domain (hFc) or to the amyloid-β (Aβ) antibody bapineuzumab (Bapi). TXB2-hFc displayed 20-fold higher brain concentrations compared with a control VNAR-hFc at 18 hours post-injection in wt mice. At the same time point, brain concentrations of Bapi-TXB2 was threefold higher than Bapi. In transgenic mice overexpressing human Aβ, the brain-to-blood concentration ratio increased with time due to interaction with intracerebral Aβ deposits. The relatively stable threefold difference between Bapi-TXB2 and Bapi was observed for up to 6 days after injection. PET imaging and ex vivo autoradiography revealed more parenchymal distribution of Bapi-TXB2 compared with Bapi. In conclusion, the TXB2 VNAR shuttle markedly increased brain uptake of protein cargo and increased brain concentrations of the Aβ binding antibody Bapi

Sources of Human Schwann Cells and the Influence of Donor Age

We evaluated several tissues as possible sources for culturing human Schwann cells. The average cell yield (total cell number/mg of nerve fascicle) obtained from adult autopsy cases and transplant organ donors was similar (2 x 104 and 2.9 x 104, respectively), but significantly higher yields were obtained from dorsal roots of pediatric patients undergoing selective dorsal rhizotomy (6.1 x 104). Fresh tissue was not essential since cells isolated from 0 to 20 h postmortem were equally viable. However, we found evidence that donor age affects the intrinsic growth rate of Schwann cells and perineurial fibroblasts in culture.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31199/1/0000101.pd