Table_2_Loss of Function of the Neural Cell Adhesion Molecule NrCAM Regulates Differentiation, Proliferation and Neurogenesis in Early Postnatal Hypothalamic Tanycytes.csv

Hypothalamic tanycytes are neural stem and progenitor cells, but little is known of how they are regulated. Here we provide evidence that the cell adhesion molecule, NrCAM, regulates tanycytes in the adult niche. NrCAM is strongly expressed in adult mouse tanycytes. Immunohistochemical and in situ hybridization analysis revealed that NrCAM loss of function leads to both a reduced number of tanycytes and reduced expression of tanycyte-specific cell markers, along with a small reduction in tyrosine hydroxylase-positive arcuate neurons. Similar analyses of NrCAM mutants at E16 identify few changes in gene expression or cell composition, indicating that NrCAM regulates tanycytes, rather than early embryonic hypothalamic development. Neurosphere and organotypic assays support the idea that NrCAM governs cellular homeostasis. Single-cell RNA sequencing (scRNA-Seq) shows that tanycyte-specific genes, including a number that are implicated in thyroid hormone metabolism, show reduced expression in the mutant mouse. However, the mild tanycyte depletion and loss of markers observed in NrCAM-deficient mice were associated with only a subtle metabolic phenotype.

下丘脑的tanycytes为神经干细胞和祖细胞，然而关于其调控机制的了解尚显不足。本研究提供了证据表明，细胞粘附分子NrCAM调控了成年生境中的tanycytes。在成年小鼠的tanycytes中，NrCAM的表达极为强烈。通过免疫组化和原位杂交分析发现，NrCAM功能丧失导致tanycytes数量减少以及tanycyte特异性细胞标记物表达降低，同时酪氨酸羟化酶阳性的弓状核神经元也出现了轻微的减少。对E16期的NrCAM突变体进行的类似分析表明，在基因表达或细胞组成上几乎没有变化，这表明NrCAM调控tanycytes，而非早期胚胎下丘脑发育。神经球和器官型分析支持了NrCAM维持细胞稳态的观点。单细胞RNA测序(scRNA-Seq)结果显示，包括与甲状腺激素代谢相关的多个基因在内的tanycyte特异性基因在突变小鼠中的表达降低。然而，NrCAM缺陷小鼠中观察到的tanycyte轻度耗竭和标记物丧失仅与微妙的代谢表型相关。