A versatile transcription factor: Multiple roles of orthopedia a (otpa) beyond its restricted localization in dopaminergic systems of developing and adult zebrafish (Danio rerio) brains

Abstract

Many transcription factors boost neural development and differentiation in specific directions and serve for identifying similar or homologous structures across species.The expression of Orthopedia (Otp) is critical for the development of certain cell groups along the vertebrate neuraxis, for example, the medial amygdala or hypothalamic neurosecretory neurons. Therefore, the primary focus of the present study is the distribution of Orthopedia a (Otpa) in the larval and adult zebrafish (Danio rerio) brain.Since Otpa is also critical for the development of zebrafish basal diencephalic dopaminergic cells, colocalization of Otpa with the catecholamine synthesizing enzyme tyrosine hydroxylase (TH) is studied. Cellular colocalization of Otpa and dopamine is only seen in magnocellular neurons of the periventricular posterior tubercular nucleus and in the posterior tuberal nucleus. Otpa-positive cells occur in many additional structures along the zebrafish neuraxis, from the secondary prosencephalon down to the hindbrain. Furthermore, Otpa expression is studied in shh-GFP and islet1-GFP transgenic zebrafish.Otpa-positive cells only express shh in dopaminergic magnocellular periventricular posterior tubercular cells, and only colocalize with islet1-GFP in the ventral zone and prerecess caudal periventricular hypothalamic zone and the perilemniscal nucleus.The scarcity of cellular colocalization of Otpa in islet1-GFP cells indicates that the Shh-islet1 neurogenetic pathway is not active in most Otpa-expressing domains. Our analysis reveals detailed correspondences between mouse and zebrafish forebrain territories including the zebrafish intermediate nucleus of the ventral telencephalon and the mouse medial amygdala. The zebrafish preoptic Otpa-positive domain represents the neuropeptidergic supraopto-paraventricular region of all tetrapods. Otpa domains in the zebrafish basal plate hypothalamus suggest that the ventral periventricular hypothalamic zone corresponds to the otp-expressing basal hypothalamic tuberal field in the mouse. Furthermore, the mouse otp domain in the mammillary hypothalamusThis is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Genoarchitectonics of the larval zebrafish diencephalon

“…The pax7a domain in PTa extends to all levels of cytologically defined th1-positive cell groups (i.e., TPp/PVO/PTN). However, as mentioned, th1 cells of PTN continue more caudally (see Figure 9b,i) to y-level 497, and otpa accompanies these cells in the atlas (which is expected because of its exclusive co-localization with th1 in PTN/TPp dopamine cells; Eugenin von Bernhardi et al, 2022). However, the weakness of signal strength (even at maximal intensification) for pax7a and otpa expression in deep brain parts precludes a final decision on the true caudal extent of PTa.…”

“…In PTa, but not in prethalamus, otpa is cellularly co-expressed with dopaminergic cell markers (TPp and PTN), the only CNS dopamine cells that do so in the zebrafish brain (Eugenin von Bernhardi et al, 2022). Of note, otpa-positive cells are also present in the telencephalon (Vi, the teleostean medial amygdala; Biechl et al, 2017), preoptic region (Figure 9o: note preoptic recess, PoR; see also Affaticati et al, 2015), and various domains in basal hypothalamus (Figure 9o) and brainstem (see for details in Eugenin von Bernhardi et al, 2022). The LIM/homeodomain gene islet1 extends from its prethalamic domain into the PTa to the level of TPp.…”

An atlas and database of neuropeptide gene expression in the adult zebrafish forebrain

“…; https://doi.org/10.1101/2023.03. 29.534505 doi: bioRxiv preprint were made publicly available as a database. Based on these data, we performed detailed neuroanatomical analyses of the hypothalamus.…”

“…; https://doi.org/10.1101/2023.03. 29.534505 doi: bioRxiv preprint 139. Zhou, W., Li, S., Liu, Y., Qi, X., Chen, H., Cheng, C. H., Liu, X., Zhang, Y., & Lin, H. (2012).…”

“…; https://doi.org/10.1101/2023.03. 29.534505 doi: bioRxiv preprint many transgenic zebrafish have been produced using the enhancer/promoter regions of various neuropeptide genes (Liu et al, 2003;Levitas-Djerbi et al, 2015;Förster et al, 2017;Koide et al, 2018;Shainer et al, 2019;Song et al, 2021). By closely examining the expression patterns of neuropeptides and neurotransmitters, we found that some of the hypothalamic nuclei described in the zebrafish reference brain atlas (Wullimann et al, 1996) contained multiple subregions with different expression patterns of neuropeptides, which we defined as subnuclei.…”