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Familial neurohypophyseal diabetes insipidus (FNDI) is a degenerative disease of vasopressin (AVP) neurons. Studies in mouse in vivo models indicate that accumulation of mutant AVP prehormone is associated with FNDI pathology. However, studying human FNDI pathology in vivo is technically challenging. Therefore, an in vitro human model needs to be developed. When exogenous signals are minimized in the early phase of differentiation in vitro, mouse embryonic stem cells (ESCs) differentiate into AVP neurons, whereas human ESCs/induced pluripotent stem cells (iPSCs) die. Human ES/iPSCs are generally more similar to mouse epiblast stem cells compared to mouse ESCs, which are termed as primed and naive, respectively. In this study, we converted human FNDI-specific iPSCs from primed to naive cells, and found improved cell survival under minimal exogenous signals and differentiation into rostral hypothalamic organoids. Overall, this method provides a simple and straightforward differentiation direction, which may improve the efficiency of hypothalamic differentiation.

Tanycytes have recently been accepted as neural stem/progenitor cells in the postnatal hypothalamus. Persistent retina and anterior neural fold homeobox (Rax) expression is characteristic of tanycytes in contrast to its transient expression of whole hypothalamic precursors. In this study, we found that Rax^+ residual cells in the maturation phase of hypothalamic differentiation in mouse embryonic stem cell (mESC) cultures had similar characteristics to ventral tanycytes. They expressed typical neural stem/progenitor cell markers, including Sox2, vimentin, and nestin, and differentiated into mature neurons and glial cells. Quantitative RT-PCR analysis showed that Rax^+ residual cells expressed Fgf-10, Fgf-18, and Lhx2, which are expressed by ventral tanycytes. They highly expressed tanycyte-specific genes Dio2 and Gpr50 compared with Rax^+ early hypothalamic progenitor cells. Therefore, Rax^+ residual cells in the maturation phase of hypothalamic differentiation were considered to be more differentiated and similar to late progenitor cells and tanycytes. They self-renewed and formed neurospheres when cultured with exogenous FGF-2. Additionally, these Rax^+ neurospheres differentiated into three neuronal lineages (neurons, astrocytes, and oligodendrocytes), including neuropeptide Y^+ neuron, that are reported to be differentiated from ventral tanycytes toward the arcuate nuclei. Thus, Rax^+ residual cells were multipotent neural stem/progenitor cells. Rax^+ neurospheres were stably passaged and retained high Sox2 expression even after multiple passages. These results suggest the successful induction of Rax^+ tanycyte-like cells from mESCs [induced tanycyte-like (iTan) cells]. These hypothalamic neural stem/progenitor cells may have potential in regenerative medicine and as a research tool., ファイル公開日: 2020/07/01

High differentiation efficiency is one of the most important factors in developing an in vitro model from pluripotent stem cells. In this report, we improved the handling technique applied to mouse-induced pluripotent stem (iPS) cells, resulting in better differentiation into hypothalamic vasopressin (AVP) neurons. We modified the culture procedure to make the maintenance of iPS cells in an undifferentiated state much easier. Three-dimensional floating culture was demonstrated to be effective for mouse iPS cells. We also improved the differentiation method with regards to embryology, resulting in a greater number of bigger colonies of AVP neurons differentiating from mouse iPS cells. Fgf8, which was not used in the original differentiation method, increased iPS differentiation into AVP neurons. These refinements will be useful as a valuable tool for the modeling of degenerative disease in AVP neurons in vitro using disease-specific iPS cells in future studies. Keywords: AVP neuron, Hypothalamus, Mouse iPS cells, Differentiation, Maintenance

Summary Misfolded or unfolded proteins in the ER are said to be degraded only after translocation or isolation from the ER. Here, we describe a mechanism by which mutant proteins are degraded within the ER. Aggregates of mutant arginine vasopressin (AVP) precursor were confined to ER-associated compartments (ERACs) connected to the ER in AVP neurons of a mouse model of familial neurohypophysial diabetes insipidus. The ERACs were enclosed by membranes, an ER chaperone and marker protein of phagophores and autophagosomes were expressed around the aggregates, and lysosomes fused with the ERACs. Moreover, lysosome-related molecules were present within the ERACs, and aggregate degradation within the ERACs was dependent on autophagic-lysosomal activity. Thus, we demonstrate that protein aggregates can be degraded by autophagic-lysosomal machinery within specialized compartments of the ER., Graphical Abstract, Highlights • Mutant AVP precursors are confined to ERACs connected to the ER of FNDI AVP neurons • Lysosomes fuse with ERACs surrounded by phagophore-like membranes • Lysosome-related molecules are localized within ERACs • Rapamycin reduces and chloroquine increases protein aggregate accumulation in ERACs, neuroscience; cell biology; technical aspects of cell biology

Arginine-vasopressin (AVP) neurons exist in the hypothalamus, a major region of the diencephalon, and play an essential role in water balance. Here, we established the differentiation method for AVP-secreting neurons from human embryonic stem cells (hESCs) by recapitulating in vitro the in vivo embryonic developmental processes of AVP neurons. At first, the differentiation efficiency was improved. That was achieved through the optimization of the culture condition for obtaining dorsal hypothalamic progenitors. Secondly, the induced AVP neurons were identified by immunohistochemistry and these neurons secreted AVP after potassium chloride stimulation. Additionally, other hypothalamic neuropeptides were also detected, such as oxytocin, corticotropin-releasing hormone, thyrotropin-releasing hormone, pro-opiomelanocortin, agouti-related peptide, orexin, and melanin-concentrating hormone. This is the first report describing the generation of secretory AVP neurons derived from hESCs. This method will be applicable to research using disease models and, potentially, for regenerative medicine of the hypothalamus.