2022 Vol. 13, No. 2

PD0325901(MEK1/2 inhibitor) in 2i/L medium causes rapid loss of DNA methylation at the paternal differentially DNA methylation regions (DMRs) in androgenetic haploid ESCs (AG-haESCs), probably due to inhibition of Dnmts. Meanwhile, H3K4me3 deposition at paternal DMRs prevents de novo methylation of DMRs. Replacement of PD0325901 with SRC inhibitor (CGP77675, termed a2i/L), however, enables long-term maintenance of DNA methylation at paternal DMRs in AG-haESCs generated through a two-step protocol based on a2i/L (TSa2i/L). CGP77675 enhances the protein level of DNA methylation-related genes and promotes H3K9me3 deposition at paternal DMRs. Moreover, AGhaESCs with hypermethylated H19-DMR sustain enhanced cell proliferation, further promoting paternal-DMR methylation maintenance. Together, TSa2i/L ensures epigenetic integrity of paternal DMRs in AG-haESCs that can be efficiently used as sperm replacement.

“Always learn today, stand ready to act tomorrow”—Po Tien: A pioneer of Virology in China
Xin Zhang, Huan Liu
2022, 13(2): 79-81. doi: 10.1007/s13238-021-00870-7
Genomic instability as a major mechanism for acquired resistance to EGFR tyrosine kinase inhibitors in cancer
Bing Liu, Daniela Duenas, Li Zheng, Karen Reckamp, Binghui Shen
2022, 13(2): 82-89. doi: 10.1007/s13238-021-00855-6
Nuclear cGAS: sequestration and beyond
Juli Bai, Feng Liu
2022, 13(2): 90-101. doi: 10.1007/s13238-021-00869-0
The cyclic GMP-AMP (cGAMP) synthase (cGAS) has been identified as a cytosolic double stranded DNA sensor that plays a pivotal role in the type I interferon and inflammation responses via the STING-dependent signaling pathway. In the past several years, a growing body of evidence has revealed that cGAS is also localized in the nucleus where it is associated with distinct nuclear substructures such as nucleosomes, DNA replication forks, the double-stranded breaks, and centromeres, suggesting that cGAS may have other functions in addition to its role in DNA sensing. However, while the innate immune function of cGAS is well established, the non-canonical nuclear function of cGAS remains poorly understood. Here, we review our current understanding of the complex nature of nuclear cGAS and point to open questions on the novel roles and the mechanisms of action of this protein as a key regulator of cell nuclear function, beyond its well-established role in dsDNA sensing and innate immune response.
Research Articles
Epigenetic integrity of paternal imprints enhances the developmental potential of androgenetic haploid embryonic stem cells
Hongling Zhang, Yuanyuan Li, Yongjian Ma, Chongping Lai, Qian Yu, Guangyong Shi, Jinsong Li
2022, 13(2): 102-119. doi: 10.1007/s13238-021-00890-3
The use of two inhibitors of Mek1/2 and Gsk3β (2i) promotes the generation of mouse diploid and haploid embryonic stem cells (ESCs) from the inner cell mass of biparental and uniparental blastocysts, respectively. However, a system enabling long-term maintenance of imprints in ESCs has proven challenging. Here, we report that the use of a two-step a2i (alternative two inhibitors of Src and Gsk3β, TSa2i) derivation/culture protocol results in the establishment of androgenetic haploid ESCs (AG-haESCs) with stable DNA methylation at paternal DMRs (differentially DNA methylated regions) up to passage 60 that can efficiently support generating mice upon oocyte injection. We also show coexistence of H3K9me3 marks and ZFP57 bindings with intact DMR methylations. Furthermore, we demonstrate that TSa2itreated AG-haESCs are a heterogeneous cell population regarding paternal DMR methylation. Strikingly, AGhaESCs with late passages display increased paternalDMR methylations and improved developmental potential compared to early-passage cells, in part through the enhanced proliferation of H19-DMR hypermethylated cells. Together, we establish AG-haESCs that can longterm maintain paternal imprints.
The two-stage interaction of Ebola virus VP40 with nucleoprotein results in a switch from viral RNA synthesis to virion assembly/budding
Linjuan Wu, Dongning Jin, Dan Wang, Xuping Jing, Peng Gong, Yali Qin, Mingzhou Chen
2022, 13(2): 120-140. doi: 10.1007/s13238-020-00764-0
Ebola virus (EBOV) is an enveloped negative-sense RNA virus and a member of the filovirus family. Nucleoprotein (NP) expression alone leads to the formation of inclusion bodies (IBs), which are critical for viral RNA synthesis. The matrix protein, VP40, not only plays a critical role in virus assembly/budding, but also can regulate transcription and replication of the viral genome. However, the molecular mechanism by which VP40 regulates viral RNA synthesis and virion assembly/budding is unknown. Here, we show that within IBs the N-terminus of NP recruits VP40 and is required for VLP-containing NP release. Furthermore, we find four point mutations (L692A, P697A, P698A and W699A) within the C-terminal hydrophobic core of NP result in a stronger VP40-NP interaction within IBs, sequestering VP40 within IBs, reducing VP40-VLP egress, abolishing the incorporation of NC-like structures into VP40-VLP, and inhibiting viral RNA synthesis, suggesting that the interaction of N-terminus of NP with VP40 induces a conformational change in the C-terminus of NP. Consequently, the C-terminal hydrophobic core of NP is exposed and binds VP40, thereby inhibiting RNA synthesis and initiating virion assembly/budding.
Cell-cycle length of medial ganglionic eminence progenitors contributes to interneuron fate
Ni Zong, Min Wang, Yinghui Fu, Dan Shen, Yong-Chun Yu
2022, 13(2): 141-147. doi: 10.1007/s13238-021-00851-w
Maternal heterozygous mutation in CHEK1 leads to mitotic arrest in human zygotes
Beili Chen, Jianying Guo, Ting Wang, Qianhui Lee, Jia Ming, Fangfang Ding, Haitao Li, Zhiguo Zhang, Lin Li, Yunxia Cao, Jie Na
2022, 13(2): 148-154. doi: 10.1007/s13238-021-00844-9
Correction to: A world renowned psychophysiologist: Kaoliang Chow
Lei Zhang, Lijun Wang, Benyu Guo, Yanyan Qian, Qingming Liu
2022, 13(2): 155-155. doi: 10.1007/s13238-021-00886-z