Project description:The CRISPR (clustered regulatory interspaced short palindromic repeats)/ Cas9 (CRISPR-associated protein 9) system-based precise genome editing has revolutionized biomedical studies. As the CRISPR/Cas9 system has been also recently considered to permanently cure genetic diseases via human germline genome editing, a careful risk assessment of this genome engineering tool is required in human early development. Here we perform comprehensive analysis to evaluate the potential impact of Cas9 in human early embryogenesis. We find that even in the absence of synthetic guide RNA, Cas9 can be still guided by endogenous RNAs, and cut the genome of human embryonic cells at low frequency, and the resulting DNA damage induces the intrinsic immune response. Moreover, Cas9 interferes with the spliceosome, and with the suppressor machinery (e.g. L1TD1, APOBEC3G and PIWIL4) of LINE-1 (L1) retrotransposition. Even the transient presence of Cas9 in human embryonic cells induces robust de novo L1 retrotransposition that exacerbates DNA damage, and results in compromised neurodevelopment. Besides the ethical issues, these inevitable and detrimental Cas9-associated impacts on human embryonic development raise such serious safety concerns as to question the clinical use of human germline genome editing.
Project description:The CRISPR (clustered regulatory interspaced short palindromic repeats)/ Cas9 (CRISPR-associated protein 9) system-based precise genome editing has revolutionized biomedical studies. As the CRISPR/Cas9 system has been also recently considered to permanently cure genetic diseases via human germline genome editing, a careful risk assessment of this genome engineering tool is required in human early development. Here we perform comprehensive analysis to evaluate the potential impact of Cas9 in human early embryogenesis. We find that even in the absence of synthetic guide RNA, Cas9 can be still guided by endogenous RNAs, and cut the genome of human embryonic cells at low frequency, and the resulting DNA damage induces the intrinsic immune response. Moreover, Cas9 interferes with the spliceosome, and with the suppressor machinery (e.g. L1TD1, APOBEC3G and PIWIL4) of LINE-1 (L1) retrotransposition. Even the transient presence of Cas9 in human embryonic cells induces robust de novo L1 retrotransposition that exacerbates DNA damage, and results in compromised neurodevelopment. Besides the ethical issues, these inevitable and detrimental Cas9-associated impacts on human embryonic development raise such serious safety concerns as to question the clinical use of human germline genome editing.
Project description:The CRISPR (clustered regulatory interspaced short palindromic repeats)/ Cas9 (CRISPR-associated protein 9) system-based precise genome editing has revolutionized biomedical studies. As the CRISPR/Cas9 system has been also recently considered to permanently cure genetic diseases via human germline genome editing, a careful risk assessment of this genome engineering tool is required in human early development. Here we perform comprehensive analysis to evaluate the potential impact of Cas9 in human early embryogenesis. We find that even in the absence of synthetic guide RNA, Cas9 can be still guided by endogenous RNAs, and cut the genome of human embryonic cells at low frequency, and the resulting DNA damage induces the intrinsic immune response. Moreover, Cas9 interferes with the spliceosome, and with the suppressor machinery (e.g. L1TD1, APOBEC3G and PIWIL4) of LINE-1 (L1) retrotransposition. Even the transient presence of Cas9 in human embryonic cells induces robust de novo L1 retrotransposition that exacerbates DNA damage, and results in compromised neurodevelopment. Besides the ethical issues, these inevitable and detrimental Cas9-associated impacts on human embryonic development raise such serious safety concerns as to question the clinical use of human germline genome editing.
Project description:RNA binding proteins (RBPs) interact with RNA targets to control an array of processes, including RNA splicing, stability, transport, and translation1-3. Dysfunctional RNA-RBP interactions contribute to pathogenesis of a plethora of human diseases1,4,5, underscoring the need for a greater understanding of the nature and dynamics of RNA-protein assemblies. The capacity to study native RNA-dependent protein assemblies in living cells, however, has been limited. To address this, non-isotopic ligation-based ultraviolet crosslinking immunoprecipitation6 was combined with mass spectrometry (irCLIP-RNP) to identify RNA-dependent associated proteins (RDAPs) co-bound to RNA with specific RBPs of interest. irCLIP-RNP defined landscapes of complex and multimeric protein assemblies on RNA, uncovering previously unknown patterns of RBP associations on RNA. This included cell-type-selective patterned relationships between RDAPs and primary RBPs, such as cell context-dependent reciprocal impacts of HNRNPU and NONO on each other’s RDAP landscapes. irCLIP-RNP also defined dynamic RDAP remodeling patterns in response to epidermal growth factor (EGF) and uncovered EGF-induced recruitment of UPF1 adjacent to HNRNPC to effect splicing surveillance of mRNAs that mediate cell proliferation. The development of sequential immunoprecipitation irCLIP (RE-irCLIP) supported the same-RNA-molecule co-localization of irCLIP-RNP-identified associations. Thus, irCLIP-RNP and RE-irCLIP provide a framework to identify and characterize dynamic RNA-protein assemblies in living cells.