Understanding the contribution of Adgrb1 to oligodendrocyte function Restricted; Files Only
Ettigi, Nihar (Spring 2025)
Abstract
Phagocytosis is a mechanism by which excess synapses and apoptotic cells in the brain are removed. Although microglia are typically considered the primary brain cell type that engages in phagocytosis, astrocytes have been shown to phagocytose as well, particularly in the context of removing apoptotic cells. Research from our lab demonstrated that the phagocytic G-protein coupled receptor, Adgrb1/Bai1, is involved in astrocytic phagocytosis of apoptotic cells. To determine what other astrocytic functions Adgrb1/Bai1 is involved in, and how a lack of Adgrb1/Bai1 may affect astrocyte gene expression, RNA-sequencing was performed on astrocytes that were isolated from mutant mice lacking full length Adgrb1. RNA-sequencing analysis identified 131 differentially expressed genes (DEGs) when astrocytes from mutant and wildtype littermates were compared. Unexpectedly, 59 DEGs were found to be highly expressed in oligodendrocytes and almost all of these genes (58/59) were downregulated. Therefore, we hypothesized that Adgrb1 is also involved in oligodendrocyte function. The goal of the study was to ascertain whether oligodendrocyte function is altered in Adgrb1 homozygous knockout mice. Since oligodendrocytes are known to play an important role in myelin formation, electron microscopy was conducted to investigate hippocampal myelin structure. After finding a significant difference in the structure of myelin in Adgrb1 lacking mice compared to wildtype littermates, immunohistochemistry (IHC) and western blot experiments were performed to investigate whether protein levels of the common myelin markers, Myelin Basic Protein (MBP) and Myelin Oligodendrocyte Glycoprotein (MOG) were altered. MBP is a cell adhesion protein involved in binding myelin sheaths together, whereas MOG is a cell surface protein expressed on the membrane of oligodendrocytes. Our data revealed no difference in MBP and MOG levels between the two genotypes by western blot and no difference in MBP levels in IHC. Taken together, the data in this study suggests that Adgrb1 contributes to the ability of oligodendrocytes to generate the myelin sheath, but further research will be required to fully understand the underlying mechanism. Altered myelin function may also contribute to the neurological phenotypes observed in homozygous Adgrb1 knockout mice.
Table of Contents
Introduction…………………………………………………………………………………………………. 2
Materials and Methods………………………………………………………………………………… 9
Results………………………………………………………………………………………………………….. 13
Figures and Tables
Figure 1…………………………………………….…………………………………………………………… 4
Figure 2…………………………………………….…………………………………………………………… 6
Figure 3…………………………………………….…………………………………………………………… 14
Figure 4…………………………………………….…………………………………………………………… 18
Figure 5…………………………………………….…………………………………………………………… 21
Figure 6…………………………………………….…………………………………………………………… 22
Figure 7…………………………………………….……………………………………………………….….. 24
Table 1…………………………………………….……………………………………………………………. 15
Table 2…………………………………………….……………………………………………………………. 19
Table 3…………………………………………….……………………………………………………………. 19
Table 4…………………………………………….……………………………………………………………. 19
Discussion……………………………………………………………………………………………………. 24
Conclusions…………….…………………………………………………………………………………… 29
Future Directions…………………………………………………………………………………………. 29
Limitations…………………………………………………………………………….…………………….. 31
References………………………………………………………………………………….……………….. 33
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File download under embargo until 22 May 2027 | 2025-04-10 16:55:18 -0400 | File download under embargo until 22 May 2027 |
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