Longistatin, a Plasminogen Activator, Is Key to the Availability of Blood-Meals for Ixodid Ticks

PLoS Pathogens

Takeharu Miyoshi¹  Anisuzzaman²  Naotoshi Tsuji²  Takeshi Hatta³  M. Khyrul Islam³  Kozo Fujisaki³  M. Abdul Alim³  Kayoko Yamaji³  Yasunobu Matsumoto³ 

[1] Animal Functional Genomics Laboratory, Department of Primary Industries, Attwood, Victoria, Australia;Department of Global Agricultural Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan;National Institute of Animal Health, National Agricultural and Food Research Organization, Tsukuba, Japan

关键词: Fibrin;    Gene pool;    Fibrinogen;    Ticks;    Blood;    Plasmins;    Salivary gl;    s;    Blood plasma;   

DOI  :  10.1371/journal.ppat.1001312

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Ixodid ticks are notorious blood-sucking ectoparasites and are completely dependent on blood-meals from hosts. In addition to the direct severe effects on health and productivity, ixodid ticks transmit various deadly diseases to humans and animals. Unlike rapidly feeding vessel-feeder hematophagous insects, the hard ticks feed on hosts for a long time (5−10 days or more), making a large blood pool beneath the skin. Tick's salivary glands produce a vast array of bio-molecules that modulate their complex and persistent feeding processes. However, the specific molecule that functions in the development and maintenance of a blood pool is yet to be identified. Recently, we have reported on longistatin, a 17.8-kDa protein with two functional EF-hand Ca++-binding domains, from the salivary glands of the disease vector, Haemaphysalis longicornis, that has been shown to be linked to blood-feeding processes. Here, we show that longistatin plays vital roles in the formation of a blood pool and in the acquisition of blood-meals. Data clearly revealed that post-transcriptional silencing of the longistatin-specific gene disrupted ticks' unique ability to create a blood pool, and they consequently failed to feed and replete on blood-meals from hosts. Longistatin completely hydrolyzed α, β and γ chains of fibrinogen and delayed fibrin clot formation. Longistatin was able to bind with fibrin meshwork, and activated fibrin clot-bound plasminogen into its active form plasmin, as comparable to that of tissue-type plasminogen activator (t-PA), and induced lysis of fibrin clot and platelet-rich thrombi. Plasminogen activation potentiality of longistatin was increased up to 4 times by soluble fibrin. Taken together, our results suggest that longistatin may exert potent functions both as a plasminogen activator and as an anticoagulant in the complex scenario of blood pool formation; the latter is critical to the feeding success and survival of ixodid ticks.

【 授权许可】

CC BY