The Contribution of Y Chromosome Genes to Spontaneous Differentiation of Human Embryonic Stem Cells into Embryoid Bodies In Vitro
Authors: Simin Nafian Dehkordi, Farzaneh Khani, Seyedeh Nafiseh Hassani, Hossein Baharvand, Hamid Reza Soleimanpour-Lichaei, Ghasem Hosseini Salekdeh
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Objective: Sexual dimorphism in mammals can be described as subsequent transcriptional differences from their
distinct sex chromosome complements. Following X inactivation in females, the Y chromosome is the major genetic
difference between sexes. In this study, we used a male embryonic stem cell line (Royan H6) to identify the potential
role of the male-specific region of the Y chromosome (MSY) during spontaneous differentiation into embryoid bodies
(EBs) as a model of early embryonic development.
Materials and Methods: In this experimental study, RH6 cells were cultured on inactivated feeder layers and Matrigel. In a
dynamic suspension system, aggregates were generated in the same size and were spontaneously differentiated into EBs.
During differentiation, expression patterns of specific markers for three germ layers were compared with MSY genes.
Results: Spontaneous differentiation was determined by downregulation of pluripotent markers and upregulation of
fourteen differentiation markers. Upregulation of the ectoderm markers was observed on days 4 and 16, whereas
mesoderm markers were upregulated on the 8th day and endodermic markers on days 12-16. Mesoderm markers
correlated with 8 MSY genes namely DDX3Y, RPS4Y1, KDM5D, TBL1Y, BCORP1, PRY, DAZ, and AMELY, which
were classified as a mesoderm cluster. Endoderm markers were co-expressed with 7 MSY genes, i.e. ZFY, TSPY,
PRORY, VCY, EIF1AY, USP9Y, and RPKY, which were grouped as an endoderm cluster. Finally, the ectoderm markers
correlated with TXLNGY, NLGN4Y, PCDH11Y, TMSB4Y, UTY, RBMY1, and HSFY genes of the MSY, which were
categorized as an ectoderm cluster. In contrast, 2 MSY genes, SRY and TGIF2LY, were more highly expressed in RH6
cells compared to EBs.
Conclusion: We found a significant correlation between spontaneous differentiation and upregulation of specific MSY
genes. The expression alterations of MSY genes implied the potential responsibility of their gene co-expression clusters
for EB differentiation. We suggest that these genes may play important roles in early embryonic development.