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

Abstract

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.

Longistatin in tick saliva blocks advanced glycation end-product receptor activation

“…Longistatin degrades fibrinogen and activates plasminogen, and has been shown to be very closely linked with the blood-feeding processes of ticks. In our previous communications, we have also shown that, at the biting site of longistatin-knockdown ticks, there was massive infiltration of inflammatory cells (4,21), indicating that longistatin is capable of modulating inflammatory responses of hosts. However, in our previous work, the mechanism by which longistatin prevents inflammatory responses of hosts during biting of ticks was not clearly understood.…”

“…The most robust expression was detected at the peak feeding period (96-120 hours), which is known as the rapid feeding phase (Figure 8). In the rapid feeding phase, ticks cause severe tissue damage at the site of attachment on hosts (4,5). Additionally, since RAGE also has NF-κB-binding sites and longistatin prevented NF-κB translocation, we then studied the effect of tick biting on the expression of RAGE itself.…”

“…Observations reveal that the development of a blood pool is a prerequisite to the feeding biology of ticks. Extensive tissue damage and development of a blood pool are common features in tick feeding (4,5). In fact, a blood pool can be regarded as a common niche in which a highly organized molecular interaction takes place among host, vector, and invading pathogen, and each axis wants to win to survive.…”

“…Longistatin in tick saliva blocks advanced glycation end-product receptor activation Anisuzzaman 4 Yasunobu Matsumoto, 5 Yasuhiko Yamamoto, 6 Hiroshi Yamamoto, 6 Kozo Fujisaki, 1 and Naotoshi Tsuji 2+ -dependent manner. To study the RAGE-binding ability of longistatin, purified, recombinant longistatin (rlongistatin, 0-384 nM) was reacted with immobilized commercially available RAGE.…”

RNA Interference – A Powerful Functional Analysis Tool for Studying Tick Biology and its Control

“…Longistatin [79] and acidic chitinases [80] have been found to be important in the formation of blood pool and tick cement cone, respectively. The attachment site of longistatin-silenced H. longicornis ticks did not show pathological changes, such as hemorrhagic lesions corresponding to the blood pool, while the attachment site of ticks simultaneously silenced acidic chitinases exhibited blood leakage and these ticks can be easily removed.…”