Fu Kai-Yun, Chen Feng, Jin Lin, Li Guo-Qing
Xinjiang Key Laboratory of Agricultural Biosafety, Institute of Plant Protection, Xinjiang Academy of Agricultural Sciences, Urumqi, Xinjiang, China.
Key Laboratory of Intergraded Management of Harmful Crop Vermin of China North-western Oasis, Ministry of Agriculture, Urumqi, China.
Arch Insect Biochem Physiol. 2025 Jan;118(1):e70025. doi: 10.1002/arch.70025.
The activin cascade is activated when a pair of extracellular ligand (Myoglianin, Myo; Activin β, Actβ; Dawdle, Daw) binds to two pairs of transforming growth factor β (TGF) serine-threonine receptor kinases, TGF-β type I (Baboon, Babo) and II receptors. However, the roles of activin way have not well been explored in non-Drosophilid insects. In the present paper, we compared the functions of Activin β (Actβ) ligand and receptor isoform BaboB in post-embryonic development in a defoliating ladybird Henosepilachna vigintioctopunctata. RNA interference (RNAi) for Hvactβ but not Hvbabob upregulated juvenile hormone signal, reduced ecdysone pathway and impaired larval-pupal transformation. The arresting Hvactβ RNAi larvae formed pupa-specific black markings below the larval exuviae. Thus, the impairment of metamorphosis may be caused by failing to complete ecdysis behavior due to nonfunctional muscles. Consistently, larval body sizes were smaller and adult appendages were shorter in the Hvactβ RNAi larvae, in contrast to those in the Hvbabob depleted beetles. Conversely, knockdown of Hvbabob but not Hvactβ changed the pigmentation of adult elytra. Our results suggest that Actβ exerts regulative roles in JH production, ecdysteroidogenesis and organ remodeling, thus contributing to modulate the larva-pupa-adult transformation, through a BaboB independent way in H. vigintioctopunctata.
当一对细胞外配体（肌生成抑制素，Myo；激活素β，Actβ；迟缓蛋白，Daw）与两对转化生长因子β（TGF）丝氨酸 - 苏氨酸受体激酶，即TGF-β I型受体（狒狒蛋白，Babo）和II型受体结合时，激活素级联反应被激活。然而，激活素途径在非果蝇类昆虫中的作用尚未得到充分研究。在本文中，我们比较了激活素β（Actβ）配体和受体异构体BaboB在食叶瓢虫茄二十八星瓢虫胚胎后发育中的功能。对Hvactβ而非Hvbabob进行RNA干扰（RNAi）会上调保幼激素信号，降低蜕皮激素途径并损害幼虫 - 蛹的转变。被阻滞的Hvactβ RNAi幼虫在幼虫蜕皮下形成蛹特异性黑色斑纹。因此，变态的损害可能是由于肌肉无功能导致未能完成蜕皮行为所致。一致地，与Hvbabob缺失的甲虫相比，Hvactβ RNAi幼虫的幼虫体型较小，成虫附肢较短。相反，敲低Hvbabob而非Hvactβ会改变成虫鞘翅的色素沉着。我们的结果表明，Actβ在保幼激素产生、蜕皮甾体生成和器官重塑中发挥调节作用，从而通过一种不依赖于BaboB的方式促进调节茄二十八星瓢虫幼虫 - 蛹 - 成虫的转变。
