Fibril treatment changes protein interactions of tau and α-synuclein in human neurons.

In several neurodegenerative disorders, the neuronal proteins tau and α-synuclein adopt aggregation-prone conformations capable of replicating within and between cells. To better understand how these conformational changes drive neuropathology, we compared the interactomes of tau and α-synuclein in the presence or the absence of recombinant fibril seeds. Human embryonic stem cells with an inducible neurogenin-2 transgene were differentiated into glutamatergic neurons expressing (1) WT 0N4R tau, (2) mutant (P301L) 0N4R tau, (3) WT α-synuclein, or (4) mutant (A53T) α-synuclein, each genetically fused to a promiscuous biotin ligase (BioID2). Neurons expressing unfused BioID2 served as controls. After treatment with fibrils or PBS, interacting proteins were labeled with biotin in situ and quantified using mass spectrometry via tandem mass tag labeling. By comparing interactions in mutant versus WT neurons and in fibril- versus PBS-treated neurons, we observed changes in protein interactions that are likely relevant to disease progression. We identified 45 shared interactors, suggesting that tau and α-synuclein function within some of the same pathways. Potential loci of shared interactions include microtubules, Wnt signaling complexes, and RNA granules. Following fibril treatment, physiological interactions decreased, whereas other interactions, including those between tau and 14-3-3 η, increased. We confirmed that 14-3-3 proteins, which are known to colocalize with protein aggregates during neurodegeneration, can promote or inhibit tau aggregation in vitro depending on the specific combination of 14-3-3 isoform and tau sequence.

Ex vivo gene therapy using patient iPSC-derived NSCs reverses pathology in the brain of a homologous mouse model.

Neural stem cell (NSC) transplantation is a promising strategy for delivering therapeutic proteins in the brain. We evaluated a complete process of ex vivo gene therapy using human induced pluripotent stem cell (iPSC)-derived NSC transplants in a well-characterized mouse model of a human lysosomal storage disease, Sly disease. Human Sly disease fibroblasts were reprogrammed into iPSCs, differentiated into a stable and expandable population of NSCs, genetically corrected with a transposon vector, and assessed for engraftment in NOD/SCID mice. Following neonatal intraventricular transplantation, the NSCs engraft along the rostrocaudal axis of the CNS primarily within white matter tracts and survive for at least 4 months. Genetically corrected iPSC-NSCs transplanted post-symptomatically into the striatum of adult Sly disease mice reversed neuropathology in a zone surrounding the grafts, while control mock-corrected grafts did not. The results demonstrate the potential for ex vivo gene therapy in the brain using human NSCs from autologous, non-neural tissues.

Overexpression of corticotropin-releasing factor in Barrington's nucleus neurons by adeno-associated viral transduction: effects on bladder function and behavior.

The stress-related neuropeptide, corticotropin-releasing factor (CRF), is prominent in neurons of the pontine micturition center, Barrington's nucleus. These neurons co-innervate spinal preganglionic neurons that control the bladder, and locus coeruleus (LC) neurons that provide norepinephrine innervation throughout the brain. Adeno-associated viral (AAV) vector-mediated transfer of CRF cDNA was used to increase CRF expression in Barrington's nucleus neurons and investigate the impact of a gain of function in Barrington's nucleus spinal and LC projections. AAV transfer of the reverse CRF cDNA sequence served as the control. Bladder urodynamics and behavior were assessed 4 weeks after vector injection into Barrington's nucleus. Rats with bilateral injections of AAV-CRF cDNA into Barrington's nucleus had immunohistochemical evidence of CRF overexpression in neurons and transport to the spinal cord and LC. The bladder : body weight ratio was greater and micturition pressure was less in these rats compared with controls, consistent with an inhibitory influence on bladder function. Other indices of urodynamic function were not altered. CRF innervation of the LC was increased in rats with bilateral Barrington's nucleus injections of AAV-CRF cDNA, and this was associated with increased burying behavior, an endpoint of LC activation by CRF. The results provide immunohistochemical evidence for viral vector-induced CRF overexpression in Barrington's nucleus neurons and underscore the ability of AAV vector-mediated transfer to increase CRF function in selective circuits. The findings support an inhibitory influence of CRF in Barrington's nucleus regulation of the bladder and an excitatory influence on the brain norepinephrine system that translates to behavioral activation.

Transcytosis-blocking abs elicited by an oligomeric immunogen based on the membrane proximal region of HIV-1 gp41 target non-neutralizing epitopes.

CTB-MPR(649-684), a translational fusion protein consisting of cholera toxin B subunit (CTB) and residues 649 684 of gp41 membrane proximal region (MPR), is a candidate vaccine aimed at blocking early steps of HIV-1 mucosal transmission. Bacterially produced CTB MPR(649-684) was purified to homogeneity by two affinity chromatography steps. Similar to gp41 and derivatives thereof, the MPR domain can specifically and reversibly self-associate. The affinities of the broadly-neutralizing monoclonal Abs 4E10 and 2F5 to CTB MPR(649-684) were equivalent to their nanomolar affinities toward an MPR peptide. The fusion protein's affinity to GM1 ganglioside was comparable to that of native CTB. Rabbits immunized with CTB-MPR(649-684) raised only a modest level of anti-MPR(649-684) Abs. However, a prime-boost immunization with CTB-MPR(649-684) and a second MPR(649-684)-based immunogen elicited a more productive anti-MPR(649-684) antibody response. These Abs strongly blocked the epithelial transcytosis of a primary subtype B HIV-1 isolate in a human tight epithelial model, expanding our previously reported results using a clade D virus. The Abs recognized epitopes at the N-terminal portion of the MPR peptide, away from the 2F5 and 4E10 epitopes and were not effective in neutralizing infection of CD4+ cells. These results indicate distinct vulnerabilities of two separate interactions of HIV-1 with human cells - Abs against the C-terminal portion of the MPR can neutralize CD4+-dependent infection, while Abs targeting the MPR's N-terminal portion can effectively block galactosyl ceramide dependent transcytosis. We propose that Abs induced by MPR(649-684)-based immunogens may provide broad protective value independent of infection neutralization.

Translational control of recombinant human acetylcholinesterase accumulation in plants.

BACKGROUND: Codon usage differences are known to regulate the levels of gene expression in a species-specific manner, with the primary factors often cited to be mRNA processing and accumulation. We have challenged this conclusion by expressing the human acetylcholinesterase coding sequence in transgenic plants in its native GC-rich sequence and compared to a matched sequence with (dicotyledonous) plant-optimized codon usage and a lower GC content. RESULTS: We demonstrate a 5 to 10 fold increase in accumulation levels of the "synaptic" splice variant of human acetylcholinesterase in Nicotiana benthamiana plants expressing the optimized gene as compared to the native human sequence. Both transient expression assays and stable transformants demonstrated conspicuously increased accumulation levels. Importantly, we find that the increase is not a result of increased levels of acetylcholinesterase mRNA, but rather its facilitated translation, possibly due to the reduced energy required to unfold the sequence-optimized mRNA. CONCLUSION: Our findings demonstrate that codon usage differences may regulate gene expression at different levels and anticipate translational control of acetylcholinesterase gene expression in its native mammalian host as well.