Manipulation of Signal Gradient and Transcription Factors Recapitulates: Multiple Hypothalamic Identities.

During development, the hypothalamus emerges from the ventral diencephalon and is regionalized into several distinct functional domains. Each domain is characterized by a different combination of transcription factors, including Nkx2.1, Nkx2.2, Pax6, and Rx, which are expressed in the presumptive hypothalamus and its surrounding regions, and play critical roles in defining each area. Here, we recapitulated the molecular networks formed by the gradient of Sonic Hedgehog (Shh) and the aforementioned transcription factors. Using combinatorial experimental systems of directed neural differentiation of mouse embryonic stem (ES) cells, as well as a reporter mouse line and gene overexpression in chick embryos, we deciphered the regulation of transcription factors by different Shh signal intensities. We then used CRISPR/Cas9 mutagenesis to demonstrate the mutual repression between Nkx2.1 and Nkx2.2 in a cell-autonomous manner; however, they induce each other in a non-cell-autonomous manner. Moreover, Rx resides upstream of all these transcription factors and determines the location of the hypothalamic region. Our findings suggest that Shh signaling and its downstream transcription network are required for hypothalamic regionalization and establishment.

Oral Administration of Incense Resin (Styrax benzoin) Extract Enhances Spatial Learning, Memory, and Dendrite Complexity of Mice

Abstract Hippocampus is a part of the brain that has a major role in spatial learning and memory which can be affected by herbal extracts. Incense resin (Styrax benzoin) has been used by local communities to improve intelligence. However, there is no scientific evidence of the functions of Styrax benzoin for regulating hippocampal function. The aim of this study was intended to analyze and investigate the effect of incense resin on learning, memory, and dendrite complexity of mice. Three months old male Deutch Democratic Yokohama (DDY) mice were injected orally with graded doses of 100, 150, and 200 mg/kg of incense resin aqueous extract daily for 30 days. Spatial learning and memory performance levels were tested with Y-maze alternation, novel object recognition, and Morris water maze. The branches and maximum dendritic span in the dentate gyrus were observed by the Golgi-Cox staining. Overall, our results showed that incense resin extract increased learning and memory ability, and the number of dendrite branching in the dentate gyrus.

Xenopus XsalF: anterior neuroectodermal specification by attenuating cellular responsiveness to Wnt signaling.

Here we show that XsalF, a frog homolog of the Drosophila homeotic selector spalt, plays an essential role for the forebrain/midbrain determination in Xenopus. XsalF overexpression expands the domain of forebrain/midbrain genes and suppresses midbrain/hindbrain boundary (MHB) markers and anterior hindbrain genes. Loss-of-function studies show that XsalF is essential for the expression of the forebrain/midbrain genes and for the repression of the caudal genes. Interestingly, XsalF functions by antagonizing canonical Wnt signaling, which promotes caudalization of neural tissues. XsalF is required for anterior-specific expressions of GSK3beta and Tcf3, genes encoding antagonistic effectors of Wnt signaling. Loss-of-function phenotypes of GSK3beta and Tcf3 mimic those of XsalF while injections of GSK3beta and Tcf3 rescue loss-of-function phenotypes of XsalF. These findings suggest that the forebrain/midbrain-specific gene XsalF negatively controls cellular responsiveness to posteriorizing Wnt signals by regulating region-specific GSK3beta and Tcf3 expression.