Laboratory of Gene Regulation and Development, National Institute of Child Health and Human Development, Bethesda, Maryland, United States of America.
PLoS One. 2009 Dec 24;4(12):e8462. doi: 10.1371/journal.pone.0008462.
SUMO proteins are small ubiquitin-related modifiers. All SUMOs are synthesized as propeptides that are post-translationally cleaved prior to conjugation. After processing, SUMOs become covalently conjugated to cellular targets through a pathway that is similar to ubiquitination. Ubiquitin like protein proteases/Sentrin specific proteases (Ulp/SENPs) mediate both processing and deconjugation of SUMOs. The action of Ulp/SENPs makes SUMOylation a highly dynamic post-translational modification. To investigate how Ulp/SENPs are regulated in a developmental context, we isolated and characterized all Ulp/SENPs in Xenopus laevis. Xenopus possess homologues of mammalian SENP3, 5, 6 and 7. All of these enzymes reacted with HA-tagged vinyl sulfone derivatives of SUMO-2 (HA-SU2-VS) but not SUMO-1 (HA-SU1-VS), suggesting that they act primarily on SUMO-2 and -3. In contrast, Xenopus possess a single member of the SENP1/SENP2 subfamily of Ulp/SENPs, most closely related to mammalian SENP1. Xenopus SENP1 reacted with HA-SU1-VS and HA-SU2-VS, suggesting that it acts on all SUMO paralogues. We analyzed the mRNA and protein levels for each of the Ulp/SENPs through development; we found that they show distinct patterns of expression that may involve both transcriptional and post-transcriptional regulation. Finally, we have characterized the developmental function of the most abundant Ulp/SENP found within Xenopus eggs, SENP3. Depletion of SENP3 using morpholino antisense oligonucleotides (morpholinos) caused accumulation of high molecular weight SUMO-2/3 conjugated species, defects in developing embryos and changes in the expression of some genes regulated by the transforming growth factor beta (TGF-beta) pathway. These findings collectively indicate that SUMO proteases are both highly regulated and essential for normal development.
SUMO 蛋白是小泛素相关修饰物。所有 SUMO 都是作为前体蛋白合成的，在连接前经过翻译后切割。加工后，SUMO 通过与泛素化相似的途径共价连接到细胞靶标上。泛素样蛋白蛋白酶/剪接特异性蛋白酶（Ulp/SENPs）介导 SUMO 的加工和去连接。Ulp/SENPs 的作用使 SUMO 化成为一种高度动态的翻译后修饰。为了研究 Ulp/SENPs 在发育背景下是如何被调节的，我们在非洲爪蟾中分离和鉴定了所有的 Ulp/SENPs。非洲爪蟾拥有哺乳动物 SENP3、5、6 和 7 的同源物。所有这些酶都与 SUMO-2（HA-SU2-VS）的 HA 标记乙烯砜衍生物反应，但不与 SUMO-1（HA-SU1-VS）反应，表明它们主要作用于 SUMO-2 和 -3。相比之下，非洲爪蟾拥有 Ulp/SENPs 的 SENP1/SENP2 亚家族的单个成员，与哺乳动物 SENP1 最密切相关。非洲爪蟾 SENP1 与 HA-SU1-VS 和 HA-SU2-VS 反应，表明它作用于所有 SUMO 同源物。我们通过发育过程分析了每个 Ulp/SENP 的 mRNA 和蛋白质水平；我们发现它们表现出不同的表达模式，可能涉及转录和转录后调节。最后，我们对在非洲爪蟾卵中发现的最丰富的 Ulp/SENP SENP3 的发育功能进行了表征。使用反义寡核苷酸（morpholinos）耗尽 SENP3 会导致高分子量 SUMO-2/3 连接物的积累、胚胎发育缺陷以及转化生长因子β（TGF-β）途径调节的一些基因表达的变化。这些发现共同表明，SUMO 蛋白酶既高度调节，又是正常发育所必需的。
