BMP4 sufficiency to induce choroid plexus epithelial fate from embryonic stem cell-derived neuroepithelial progenitors.

Choroid plexus epithelial cells (CPECs) have essential developmental and homeostatic roles related to the CSF and blood-CSF barrier they produce. Accordingly, CPEC dysfunction has been implicated in many neurological disorders, such as Alzheimer's disease, and transplant studies have provided proof-of-concept for CPEC-based therapies. However, such therapies have been hindered by the inability to expand or generate CPECs in culture. During development, CPECs differentiate from preneurogenic neuroepithelial cells and require bone morphogenetic protein (BMP) signaling, but whether BMPs suffice for CPEC induction is unknown. Here we provide evidence for BMP4 sufficiency to induce CPEC fate from neural progenitors derived from mouse embryonic stem cells (ESCs). CPEC specification by BMP4 was restricted to an early time period after neural induction in culture, with peak CPEC competency correlating to neuroepithelial cells rather than radial glia. In addition to molecular, cellular, and ultrastructural criteria, derived CPECs (dCPECs) had functions that were indistinguishable from primary CPECs, including self-assembly into secretory vesicles and integration into endogenous choroid plexus epithelium following intraventricular injection. We then used BMP4 to generate dCPECs from human ESC-derived neuroepithelial cells. These findings demonstrate BMP4 sufficiency to instruct CPEC fate, expand the repertoire of stem cell-derived neural derivatives in culture, and herald dCPEC-based therapeutic applications aimed at the unique interface between blood, CSF, and brain governed by CPECs.

Puromycin-sensitive aminopeptidase (PSA/NPEPPS) impedes development of neuropathology in hPSA/TAU(P301L) double-transgenic mice.

Accumulation of neurotoxic hyperphosphorylated TAU protein is a major pathological hallmark of Alzheimer disease and other neurodegenerative dementias collectively called tauopathies. Puromycin-sensitive aminopeptidase (PSA/NPEPPS) is a novel modifier of TAU-induced neurodegeneration with neuroprotective effects via direct proteolysis of TAU protein. Here, to examine the effects of PSA/NPEPPS overexpression in vivo in the mammalian system, we generated and crossed BAC-PSA/NPEPPS transgenic mice with the TAU(P301L) mouse model of neurodegeneration. PSA/NPEPPS activity in the brain and peripheral tissues of human PSA/NPEPPS (hPSA) mice was elevated by ∼2-3-fold with no noticeable deleterious physiological effects. Double-transgenic animals for hPSA and TAU(P301L) transgenes demonstrated a distinct trend for delayed paralysis and showed significantly improved motor neuron counts, no gliosis and markedly reduced levels of total and hyperphosphorylated TAU in the spinal cord, brain stem, cortex, hippocampus and cerebellum of adult and aged animals when compared with TAU(P301L) mice. Furthermore, endogenous TAU protein abundance in human neuroblastoma SH-SY5Y cells was significantly reduced or augmented by overexpression or knockdown of PSA/NPEPPS, respectively. This study demonstrated that without showing neurotoxic effects, elevation of PSA/NPEPPS activity in vivo effectively blocks accumulation of soluble hyperphosphorylated TAU protein and slows down the disease progression in the mammalian system. Our data suggest that increasing PSA/NPEPPS activity may be a feasible therapeutic approach to eliminate accumulation of unwanted toxic substrates such as TAU.

Integrative gene-tissue microarray-based approach for identification of human disease biomarkers: application to amyotrophic lateral sclerosis.

Advances in genomics and proteomics permit rapid identification of disease-relevant genes and proteins. Challenges include biological differences between animal models and human diseases, high discordance between DNA and protein expression data and a lack of experimental models to study human complex diseases. To overcome some of these limitations, we developed an integrative approach using animal models, postmortem human material and a combination of high-throughput microarray methods to identify novel molecular markers of amyotrophic lateral sclerosis (ALS). We used laser capture microdissection coupled with microarrays to identify early transcriptome changes occurring in spinal cord motor neurons or surrounding glial cells. Two models of familial motor neuron disease, SOD1(G93A) and TAU(P301L), transgenic mice were used at the presymptomatic stage. Identified gene expression changes were predominantly model-specific. However, several genes were regulated in both models. The relevance of identified genes as clinical biomarkers was tested in the peripheral blood transcriptome of presymptomatic SOD1(G93A) animals using custom-designed ALS microarray. To confirm the relevance of identified genes in human sporadic ALS (SALS), selected corresponding protein products were examined by high-throughput immunoassays using tissue microarrays constructed from human postmortem spinal cord tissues. Genes that were identified by these experiments and located within a linkage region associated with familial ALS/frontotemporal dementia were sequenced in several families. This large-scale gene and protein expression study pointing to distinct molecular mechanisms of TAU- and SOD1-induced motor neuron degeneration identified several new SALS-relevant proteins (CNGA3, CRB1, OTUB2, MMP14, SLK, DDX58, RSPO2) and putative blood biomarkers, including Nefh, Prph and Mgll.