Matrix metalloproteinases (MMPs) are the major proteinases that process or degrade numerous extracellular matrix (ECM) components and are evolutionarily conserved from nematodes to humans. During molting in insects, the old cuticle is removed and replaced by a new counterpart. Although the regulatory mechanisms of hormones and nutrients in molting have been well studied, very little is known about the roles of ECM-modifying enzymes in this process. Here, we found that MMPs are necessary for imaginal molting of the American cockroach, Periplaneta americana. Inhibition of Mmp activity via inhibitor treatment led to the failure of eclosion and wing expansion. Five Mmps genes were identified from the P. americana genome, and PaMmp2 played the dominant roles during molting. Further microscopic investigations showed that newly formed adult cuticles were attenuated and that then chitin content was reduced upon Mmp inhibition. Transcriptomic analysis of the integument demonstrated that multiple signaling and metabolic pathways were changed. Microscopic investigation of the wings showed that epithelial cells were restrained together because they were incapable of degrading the ECM upon Mmp inhibition. Transcriptomic analysis of the wing identified dozens of possible genes functioned in wing expansion. This is the first study to show the essential roles of Mmps in the nymph-adult transition of hemimetabolous insects.

基质金属蛋白酶 (MMP) 是处理或降解大量细胞外基质 (ECM) 成分的主要蛋白酶，并且在从线虫到人类的进化上都是保守的。在昆虫蜕皮期间，旧的角质层被去除并被新的对应物取代。尽管激素和营养物质在蜕皮过程中的调节机制已经得到了很好的研究，但对 ECM 修饰酶在这一过程中的作用知之甚少。在这里，我们发现 MMPs 对于美洲蟑螂Periplaneta americana 的成虫蜕皮是必要的。通过抑制剂处理抑制 Mmp 活性导致羽化和翅膀扩张失败。从美洲假单胞菌基因组中鉴定出五个 Mmps 基因，PaMmp2在蜕皮过程中起主导作用。进一步的显微镜研究表明，新形成的成年角质层减弱，然后在 Mmp 抑制后几丁质含量降低。对外皮的转录组学分析表明，多种信号传导和代谢途径发生了改变。机翼的显微研究表明上皮细胞被限制在一起，因为它们在 Mmp 抑制时不能降解 ECM。机翼的转录组学分析确定了数十种可能在机翼扩张中起作用的基因。这是第一项显示 Mmps 在半代谢昆虫的若虫-成虫转变中的重要作用的研究。