利用秀丽隐杆线虫模型研究CT14在发育中的功能

doi:10.3969/j.issn.1674-8115.2024.07.008

摘要/Abstract

摘要：

目的·使用模式生物秀丽隐杆线虫（简称线虫）研究癌-睾丸抗原14（cancer-testis antigen 14，CT14）对其胚胎及幼虫发育的影响，探索CT14在发育中的潜在功能和作用机制。方法·利用显微注射构建可诱导表达人源CT14（HsCT14）、缺失CT14特异性中间序列（CT14-specific intermediate region，CIR）的截短突变体HsCT14_?CIR及绿色荧光蛋白对照的转基因线虫品系，观察并比较全长和截短突变体CT14表达后对线虫虫卵的胚胎发育及幼虫发育过程的影响。构建可诱导表达食蟹猕猴（Macaca fascicularis）和倭狐猴（Microcebus murinus）CT14的线虫品系，比较异源表达不同灵长类种属来源的CT14对线虫虫卵孵化率及幼虫成虫率的影响。通过Smart-seq转录组测序技术分析CT14表达引起的线虫胚胎的基因表达差异，并采用京都基因与基因组百科全书（Kyoto Encyclopedia of Genes and Genomes，KEGG）通路富集分析和基因集富集分析（Gene Set Enrichment Analysis，GSEA），进一步探索线虫胚胎中受CT14影响的相关生物学过程及通路。结果·HsCT14及其截短突变体HsCT14_?CIR的诱导表达显著降低了线虫虫卵孵化率，其中HsCT14的表达对孵化率的影响较大。微分干涉对比（differential interference contrast，DIC）显微技术观察显示，表达HsCT14的线虫胚胎在发育的comma期表现出明显的形态学异常。HsCT14及其截短突变体HsCT14_?CIR表达后的线虫幼虫成虫率显著低于绿色荧光蛋白对照组，并出现生长阻滞现象，其中HsCT14的表达对成虫率的影响较大。食蟹猕猴CT14（MfCT14）的表达对线虫虫卵孵化率及幼虫成虫率的影响与人源HsCT14相似，而倭狐猴CT14（MmCT14）的表达对上述指标的影响显著低于HsCT14和MfCT14。Smart-seq转录组测序结果显示，CT14的表达可能影响线虫胚胎的多个生物学过程，涉及ATP依赖的染色质重塑过程和DNA复制通路等。结论·CT14的异源表达显著干扰线虫的胚胎发育和幼虫发育，CIR起了关键的增强作用。推测CT14可能通过影响染色质重塑等多个通路的基因表达，在发育生物学中发挥重要调节作用。

关键词: 癌-睾丸抗原, 癌-睾丸抗原14, 秀丽隐杆线虫, 胚胎发育, 幼虫发育

Abstract:

Objective ·To investigate the effects of the cancer-testis antigen 14 (CT14) on embryonic and larval development in nematodes by using the model organism Caenorhabditis elegans (C. elegans), aiming to uncover its potential functions and mechanisms during development. Methods ·Transgenic C. elegans strains were constructed by using microinjection for the inducible expression of human CT14 (HsCT14), a truncated mutant of CT14 (HsCT14_?CIR) lacking CT14-specific intermediate region (CIR), and a green fluorescent protein (GFP) control. The impacts of full-length and truncated mutant CT14 on nematode embryonic and larval development were analyzed and compared. Additionally, transgenic C. elegans strains with inducible expression of CT14 from various primates, including the crab-eating macaque (Macaca fascicularis) and mouse lemur (Microcebus murinus), were also constructed to assess the effects on egg hatching and larval-to-adult transformation rates. The differential gene expression in nematode embryos induced by CT14 was analyzed by Smart-seq transcriptome sequencing, with further insights gained through KEGG (Kyoto Encyclopedia of Genes and Genomes) and GSEA (Gene Set Enrichment Analysis), to explore the involved biological processes and pathways. Results ·The induced expression of HsCT14 and its truncated mutant HsCT14_?CIR significantly reduced the hatching rate of nematode eggs, with a more pronounced effect observed in HsCT14-expressing strains. Differential interference contrast (DIC) microscopy imaging revealed significant morphological abnormalities in embryos expressing HsCT14 during the comma stage. Nematodes expressing HsCT14 or HsCT14_?CIR exhibited developmental arrest in larvae and substantially lower larval-to-adult transformation rates compared to the GFP control. The impact was more pronounced in nematodes expressing HsCT14 than those with HsCT14_?CIR. The expression of Macaca fascicularis CT14 (MfCT14) exhibited significant effects on the hatching rate and adult transformation rate, similar to that of HsCT14, while the expression of Microcebus murinus CT14 (MmCT14) displayed significantly reduced impact compared to HsCT14 and MfCT14. Smart-seq results indicated that CT14 expression affected various biological processes in nematode embryos, related to ATP-dependent chromatin remodeling and DNA replication. Conclusion ·Ectopic expression of the cancer-testis antigen CT14 significantly disrupts both embryonic and larval developments in C. elegans, with the CIR sequence substantially enhancing this effect. It suggests that CT14 may play an important regulatory role in biological development by affecting gene expression in multiple pathways, including chromatin remodeling.

Key words: cancer-testis antigen, cancer-testis antigen 14 (CT14), Caenorhabditis elegans, embryonic development, larval development

中图分类号:

R714.51

杨舒雯, 陈娟, 杨琴, 雷鸣, 黄晨辉. 利用秀丽隐杆线虫模型研究CT14在发育中的功能[J]. 上海交通大学学报（医学版）, 2024, 44(7): 871-882.

YANG Shuwen, CHEN Juan, YANG Qin, LEI Ming, HUANG Chenhui. Study on the developmental function of CT14 using the model organism Caenorhabditis elegans[J]. Journal of Shanghai Jiao Tong University (Medical Science), 2024, 44(7): 871-882.

图/表 7

表1 qPCR引物序列

Tab 1 Sequences of primers for qPCR

Gene	Forward sequence (5′→3′)	Reverse sequence (5′→3′)
CT14	GTCACCTGAGAAAGGTGAAGCAC	GTCACCTGAGAAAGGTGAAGCAC
GFP	CTGTTCCATGGCCAACACTTG	CTGTTCCATGGCCAACACTTG
Act-1	CCAGGAATTGCTGATCGTATG	GGAGAGGGAAGCGAGGATAG

图1 转基因线虫中CT14的诱导表达Note： A. Schematic diagram of the structure of HsCT14 gene and protein. Illustration of the HsCT14 gene highlights its N-terminal, C-terminal, and the CIR sequences. B. The Tet/Q hybrid system for robust control of transgene expression in C. elegans. Downstream gene expression was initiated in the presence of Dox. Prpl-28—promoter of rpl-28; rTetR—reverse Tet repressor; QFAD—the QF activation domain; mKate—a red fluorescent marker protein; TetR—Tet repressor; pes-10—the minimal promoter from pes-10; P2A—P2A peptide. C. Transgenic strains only produced the red fluorescent protein mKate in the absence of Dox. Upon induction with 0.1 ng/μL Dox, GFP was expressed. Scale bar: 2 000 μm. D. Enlarged views of HsCT14 transgenic strains under Dox+ and Dox－ conditions. Scale bar: 500 μm. E. Quantitative PCR (qPCR) analysis to examine mRNA expression levels of HsCT14 and GFP in transgenic strains. The values for HsCT14 (Dox－) were set as 1. F. Immunofluorescence staining of CT14 (red) in transgenic strains under Dox+ and Dox－ conditions. DNA was stained with DAPI (blue). ①P=0.000, compared with the HsCT14 (Dox－) group. Scale bar: 30 μm.

Fig 1 Inducible expression of CT14 in transgenic C. elegans strains

图2 转基因线虫的虫卵孵化表型Note： A. Construction of target protein expression for three transgenic strains: HsCT14, HsCT14?CIR, and GFP. B. Statistical analysis of the hatching rates of wild type (N2) and transgenic strains under Dox+ and Dox－ conditions. n: N2=250, HsCT14 (Dox－)=230, HsCT14 (Dox+)=542, HsCT14?CIR (Dox+)=589, GFP (Dox+)=827. C. Examination of egg hatching after 24 h of Dox induction. ①P=0.000, compared with the GFP (Dox+) group.

Fig 2 Hatching phenotype of transgenic nematodes

图3 转基因线虫的胚胎发育形态Note： A. Examination of embryonic development and morphological changes in transgenic nematode strains by using DIC microscopy. Scale bar: 30 μm. B. Statistical analysis of the proportion of transgenic nematode embryos that exhibited morphological changes following the induction of target protein expression with Dox. ①P=0.000, compared with the GFP (Dox+) group.

Fig 3 Morphological characterization of embryonic development in transgenic nematodes

图4 CT14的异源表达阻滞线虫幼虫的发育Note： A. Developmental progression of both wild type and transgenic C. elegans larvae, starting from the L1 stage, within 48 h of induction with 0.1 ng/μL Dox. B. Statistical analysis of the proportion of adult individuals after 48 h of culture under 0.1 ng/μL Dox induction (n=100). ①P=0.000, compared with the HsCT14 (Dox－) group; ②P=0.000, compared with the HsCT14 (Dox+) group.

Fig 4 Inhibitory effects of ectopic CT14 expression on nematode larval development

图5 不同灵长类CT14表达对虫卵孵化及幼虫发育的影响Note： A. Domain composition of CT14 homologs in HsCT14, MfCT14 and MmCT14. B. Statistical analysis of the hatching rates of transgenic C.elegans eggs induced to express HsCT14, MfCT14 and MmCT14 in the presence of 0.1 ng/μL Dox. n: HsCT14=507, MfCT14=773, MmCT14=727. C. Statistical analysis showing the proportion of adult individuals that developed from the L1 larval stage within 48 h under 0.1 ng/μL Dox induction. n=100 for each group. ①P=0.001, ③P=0.002, compared with the MmCT14 group; ②P=0.000, ④P=0.005, compared with the HsCT14 group.

Fig 5 Impacts of the expression of CT14 homologs from different primates on egg hatching and larval developmentin C.elegans

图6 线虫胚胎中CT14的异源表达对基因表达调控、DNA复制以及TGF-β通路的影响Note： A. Volcano plot showing differential gene expression between HsCT14-expressing and non-induced embryos. Upregulated genes are indicated in red, downregulated genes in blue, and genes with no significant expression changes are in gray. B. Heatmap illustrating the alterations in gene expression associated with HsCT14 induction, focusing on genes linked to the metabolic pathway, chromatin remodeling processes, TGF-β signaling pathway, and DNA replication processes. C. KEGG pathway-based enrichment analysis of downregulated differentially expressed genes in C. elegans embryos expressing HsCT14. D. KEGG analysis of upregulated differentially expressed genes in C. elegans embryos expressing HsCT14. E. GSEA highlighting the downregulation of genes involved in chromatin remodeling in C. elegans embryos expressing HsCT14. F. GSEA highlighting the downregulation of the DNA replication pathway in C. elegans embryos expressing HsCT14.

Fig 6 Effects of ectopic expression of CT14 on the regulation of gene expression, the TGF-β pathway and DNA replication in C. elegans embryos

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