A cell-cycle-dependent GARP-like transcriptional repressor regulates the initiation of differentiation in Giardia lamblia.
A cell-cycle-dependent GARP-like transcriptional repressor regulates the initiation of differentiation in Giardia lamblia.
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DOI：
10.1073/pnas.2204402119
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发表时间：
2022-05-31
影响因子：
11.1
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中科院分区：
文献类型：
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生命周期阶段之间的过渡是寄生性病原体的一个共同特征，必须优化其调节以平衡感染的持续性和传播。早期转录因子（TF）调节分化的承诺是完全未知的贾第鞭毛虫。在这项工作中，我们确定了Golden 2，ARR-B，Psr-1-like protein 1（GARP）-like protein 4（GLP 4），一种以前未表征的GARP样TF，作为一种早期作用的转录抑制因子，抑制G1+S细胞进入包囊化途径。因此，GLP 4是控制增殖生长和终末分化成感染性囊肿之间平衡的关键调节因子。分化的转录调控是寄生病原体适应环境变化和调节传播的关键。在包囊刺激，蓝氏贾第鞭毛虫转移的细胞周期的分布向G2期，并诱导表达的囊壁蛋白（CWP）在2至4小时内，表明关键的调节步骤发生在第一个4小时的包囊。然而，转录因子（TF）在包囊形成中的作用主要是在以后的时间点研究的。转铁蛋白如何启动成囊并将其与细胞周期联系起来仍然是个谜。在这里，我们系统地筛选了六个假定的早期上调转录因子的核定位，建立了他们的动态表达谱，并确定其功能作用，在调节成囊。我们发现了一个关键的阻遏物，Golden 2，ARR-B，Psr-1样蛋白1（GARP）样蛋白4（GLP 4），在包囊形成刺激30分钟后迅速增加，并下调包囊形成特异性标志物，包括CWP和包囊N-乙酰半乳糖胺途径中的酶。GLP 4的消耗增加了囊肿的产生。重要的是，我们观察到G2+M细胞表现出更高水平的CWP 1，这是由成髓细胞增多症结构域蛋白2（MYB 2）激活引起的，MYB 2是一种以前与贾第虫包囊有关的TF。GLP 4上调发生在G1+S细胞中，表明在细胞周期的G1+S期抑制MYB 2和包囊形成特异性基因中的作用。此外，我们证明了GLP 4的缺失上调MYB 2并促进成囊，而GLP 4的过表达下调MYB 2并抑制成囊。总之，这些结果表明，贾第虫采用剂量依赖性转录反应，涉及细胞周期调控的阻遏物GLP 4协调MYB 2和进入成囊途径。
Transition between life cycle stages is a common feature among parasitic pathogens, and its regulation must be optimized to balance persistence of infection with transmission. The early transcription factors (TFs) regulating commitment to differentiate are totally unknown in Giardia. In this work, we identified Golden2, ARR-B, Psr-1–like protein 1 (GARP)–like protein 4 (GLP4), a previously uncharacterized GARP-like TF, as an early-acting transcriptional repressor that inhibits G1+S cells from entering the encystation pathway. GLP4 is therefore a key regulator controlling the balance between proliferative growth and terminal differentiation into infective cysts. Transcriptional regulation of differentiation is critical for parasitic pathogens to adapt to environmental changes and regulate transmission. In response to encystation stimuli, Giardia lamblia shifts the distribution of the cell cycle toward G2 and induces the expression of cyst wall proteins (CWPs) within 2 to 4 h, indicating that key regulatory steps occur within the first 4 h of encystation. However, the role of transcription factors (TFs) in encystation has primarily been investigated at later time points. How TFs initiate encystation and link it to the cell cycle remains enigmatic. Here, we systematically screened six putative early up-regulated TFs for nuclear localization, established their dynamic expression profiles, and determined their functional role in regulating encystation. We found a critical repressor, Golden2, ARR-B, Psr-1–like protein 1 (GARP)–like protein 4 (GLP4), that increases rapidly after 30 min of encystation stimuli and down-regulates encystation-specific markers, including CWPs and enzymes in the cyst N-acetylgalactosamine pathway. Depletion of GLP4 increases cyst production. Importantly, we observe that G2+M cells exhibit higher levels of CWP1, resulting from the activation of myeloblastosis domain protein 2 (MYB2), a TF previously linked to encystation in Giardia. GLP4 up-regulation occurs in G1+S cells, suggesting a role in repressing MYB2 and encystation-specific genes in the G1+S phase of the cell cycle. Furthermore, we demonstrate that depletion of GLP4 up-regulates MYB2 and promotes encystation while overexpression of GLP4 down-regulates MYB2 and represses encystation. Together, these results suggest that Giardia employs a dose-dependent transcriptional response that involves the cell-cycle–regulated repressor GLP4 to orchestrate MYB2 and entry into the encystation pathway.
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影响因子：
3.8
作者：
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