Collette Jantzen C, Choubey Lisha, Smith Karen Müller
Department of Biology, University of Louisiana at Lafayette, Lafayette, LA, United States of America.
PeerJ. 2017 Jun 29;5:e3519. doi: 10.7717/peerj.3519. eCollection 2017.
Fibroblast growth factors (FGFs) and their receptors (FGFRs) are involved in the development and function of multiple organs and organ systems, including the central nervous system (CNS). FGF signaling via FGFR1, one of the three FGFRs expressed in the CNS, stimulates proliferation of stem cells during prenatal and postnatal neurogenesis and participates in regulating cell-type ratios in many developing regions of the brain. Anomalies in FGFR1 signaling have been implicated in certain neuropsychiatric disorders. expression has been shown, via hybridization, to vary spatially and temporally throughout embryonic and postnatal development of the brain. However, hybridization lacks sufficient resolution to identify which cell-types directly participate in FGF signaling. Furthermore, because antibodies raised against FGFR1 commonly cross-react with other members of the FGFR family, immunocytochemistry is not alone sufficient to accurately document expression. Here, we elucidate the identity of expressing cells in both the embryonic and perinatal mouse brain.
To do this, we utilized a BAC line () obtained from the GENSAT project. The line expresses EGFP under the control of a Fgfr1 promoter, thereby causing cells endogenously expressing to also present a positive GFP signal. Through simple immunostaining using GFP antibodies and cell-type specific antibodies, we were able to accurately determine the cell-type of expressing cells.
This technique revealed expression in proliferative zones containing BLBP+ radial glial stem cells, such as the cortical and hippocampal ventricular zones, and cerebellar anlage of E14.5 mice, in addition to DCX+ neuroblasts. Furthermore, our data reveal expression in proliferative zones containing BLBP+ cells of the anterior midline, hippocampus, cortex, hypothalamus, and cerebellum of P0.5 mice, in addition to the early-formed GFAP+ astrocytes of the anterior midline.
Understanding when during development and where is expressed is critical to improving our understanding of its function during neurodevelopment as well as in the mature CNS. This information may one day provide an avenue of discovery towards understanding the involvement of aberrant FGF signaling in neuropsychiatric disorders.
成纤维细胞生长因子（FGFs）及其受体（FGFRs）参与包括中枢神经系统（CNS）在内的多个器官和器官系统的发育与功能。通过FGFR1的FGF信号传导，FGFR1是中枢神经系统中表达的三种FGFR之一，在产前和产后神经发生过程中刺激干细胞增殖，并参与调节大脑许多发育区域的细胞类型比例。FGFR1信号传导异常与某些神经精神疾病有关。通过原位杂交已表明，在大脑的胚胎期和出生后发育过程中，其表达在空间和时间上有所变化。然而，原位杂交缺乏足够的分辨率来识别哪些细胞类型直接参与FGF信号传导。此外，由于针对FGFR1产生的抗体通常与FGFR家族的其他成员发生交叉反应，因此免疫细胞化学本身不足以准确记录FGFR1的表达。在这里，我们阐明了胚胎期和围产期小鼠大脑中表达FGFR1的细胞的身份。
为此，我们利用了从GENSAT项目获得的一个BAC品系（BAC-Fgfr1-EGFP）。该BAC品系在Fgfr1启动子的控制下表达EGFP，从而使内源性表达FGFR1的细胞也呈现阳性GFP信号。通过使用GFP抗体和细胞类型特异性抗体进行简单的免疫染色，我们能够准确确定表达FGFR1的细胞的细胞类型。
这项技术揭示了在含有BLBP+放射状胶质干细胞的增殖区中FGFR1的表达，例如E14.5小鼠的皮质和海马室管膜区以及小脑原基，此外还有DCX+神经母细胞。此外，我们的数据揭示了在P0.5小鼠的前中线、海马、皮质、下丘脑和小脑中含有BLBP+细胞的增殖区中FGFR1的表达，以及前中线早期形成的GFAP+星形胶质细胞中的FGFR1表达。
了解FGFR1在发育过程中的何时何地表达对于提高我们对其在神经发育以及成熟中枢神经系统中的功能的理解至关重要。这些信息也许有一天会为理解异常FGF信号传导在神经精神疾病中的作用提供一条发现途径。
