Steroid hormones in Acari, their functions and synthesis

Ogihara, Mari H.; Taylor, DeMar; Kataoka, Hiroshi

doi:10.1007/s13355-019-00631-3

Cited by 10 publications

(6 citation statements)

References 155 publications

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Section: Resultsmentioning

confidence: 99%

“…Ticks develop into adults through an incomplete metamorphosis, a process that is accomplished by molting or shedding of the exoskeleton ( 46 ). Arthropod molting is regulated by ecdysteroids, such as 20-hydroxyecdysone (20E) and ponasterone A, which are synthesized from dietary cholesterol ( 46 , 47 ). Because CD36 facilitates the transport of lipids, including cholesterol into mammalian cells, we posited that crq silencing would disrupt the molting process in I. scapularis .…”

Section: Resultsmentioning

confidence: 99%

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Croquemort elicits activation of the immune deficiency pathway in ticks

O’Neal

Singh

Rolandelli

et al. 2023

Proc. Natl. Acad. Sci. U.S.A.

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The immune deficiency (IMD) pathway directs host defense in arthropods upon bacterial infection. In Pancrustacea, peptidoglycan recognition proteins sense microbial moieties and initiate nuclear factor-κB-driven immune responses. Proteins that elicit the IMD pathway in non-insect arthropods remain elusive. Here, we show that an Ixodes scapularis homolog of croquemort (Crq), a CD36-like protein, promotes activation of the tick IMD pathway. Crq exhibits plasma membrane localization and binds the lipid agonist 1-palmitoyl-2-oleoyl- sn -glycero-3-phosphoglycerol. Crq regulates the IMD and jun N-terminal kinase signaling cascades and limits the acquisition of the Lyme disease spirochete B. burgdorferi . Additionally, nymphs silenced for crq display impaired feeding and delayed molting to adulthood due to a deficiency in ecdysteroid synthesis. Collectively, we establish a distinct mechanism for arthropod immunity outside of insects and crustaceans.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Croquemort elicits activation of the immune deficiency pathway in ticks

O’Neal

Singh

Rolandelli

et al. 2023

Proc. Natl. Acad. Sci. U.S.A.

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“…We also uncovered hemocytes specialized towards cellular proliferation. These hemocytes expressed genes involved in ecdysteroid biosynthesis, which is essential for regulating molting and development ( 7, 41 ). Metabolic hemocytes were enriched in solute transport, lipid and protein metabolism, histamine binding and detoxification genes.…”

Section: Discussionmentioning

confidence: 99%

“…We observed defects in tick molting when hemocyte subtypes and astakine and hemocytin levels were altered. As opposed to insects, Acari rely solely on the synthesis of ecdysteroids derived from cholesterol for molting ( 7, 41 ). Our results suggest the involvement of hemocytes in ecdysteroid synthesis and transport as homologs of most genes related to lipid metabolism were altered after a blood meal.…”

Section: Discussionmentioning

confidence: 99%

Tick hemocytes have pleiotropic roles in microbial infection and arthropod fitness

Rolandelli,

Laukaitis-Yousey,

Bogale

et al. 2023

Preprint

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Uncovering the complexity of systems in non-model organisms is critical for understanding arthropod immunology. Prior efforts have mostly focused on Dipteran insects, which only account for a subset of existing arthropod species in nature. Here, we describe immune cells or hemocytes from the clinically relevant tickIxodes scapularisusing bulk and single cell RNA sequencing combined with depletion via clodronate liposomes, RNA interference, Clustered Regularly Interspaced Short Palindromic Repeats activation (CRISPRa) and RNA-fluorescencein situhybridization (FISH). We observe molecular alterations in hemocytes upon tick infestation of mammals and infection with either the Lyme disease spirocheteBorrelia burgdorferior the rickettsial agentAnaplasma phagocytophilum. We predict distinct hemocyte lineages and reveal clusters exhibiting defined signatures for immunity, metabolism, and proliferation during hematophagy. Furthermore, we perform a mechanistic characterization of twoI. scapularishemocyte markers:hemocytinandastakine. Depletion of phagocytic hemocytes affectshemocytinandastakinelevels, which impacts blood feeding and molting behavior of ticks. Hemocytin specifically affects the c-Jun N-terminal kinase (JNK) signaling pathway, whereas astakine alters hemocyte proliferation inI. scapularis. Altogether, we uncover the heterogeneity and pleiotropic roles of hemocytes in ticks and provide a valuable resource for comparative biology in arthropods.

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“…Vg is later taken up by the oocytes as vitellin (Vn) to serve as a nutritional reserve for embryos. The regulatory pathways of vitellogenesis are well studied in insects (reviewed by Tufail et al ., 2014; Roy et al ., 2018) and have been described in some detail in ticks (reviewed by Rees, 2004; Roe et al ., 2013; Ogihara et al ., 2019).…”

Section: Introductionmentioning

confidence: 99%

Production of the yolk protein precursor vitellogenin is mediated by target of rapamycin (TOR) in the soft tick Ornithodoros moubata (Acari: Argasidae)

et al. 2022

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Initiation of vitellogenesis by blood feeding is essential for egg maturation in ticks. Nutrients derived from the blood meal are utilized by female ticks to synthesize the yolk protein precursor vitellogenin (Vg). Engorged Ornithodoros moubata ticks can synthesize Vg whether mated or virgin, thus O. moubata is an excellent model for studying the relative roles of blood feeding and mating in tick vitellogenesis. Injection of rapamycin into engorged O. moubata resulted in a reduction of ovarian growth and yolk accumulation in the oocytes of mated females. OmVg expression in the midgut and fat body and protein concentrations in the hemolymph significantly decreased in mated ticks after injection with rapamycin, indicating that inhibition of the nutrient‐sensing target of rapamycin (TOR) pathway disrupts egg maturation at the levels of Vg expression and synthesis. These results suggest that the TOR‐signaling pathway induces vitellogenesis in response to nutritional stimulation after a blood meal in O. moubata and is functionally independent of the mating‐induced pathway.

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Steroid hormones in Acari, their functions and synthesis

Cited by 10 publications

References 155 publications

Croquemort elicits activation of the immune deficiency pathway in ticks

Croquemort elicits activation of the immune deficiency pathway in ticks

Tick hemocytes have pleiotropic roles in microbial infection and arthropod fitness

Production of the yolk protein precursor vitellogenin is mediated by target of rapamycin (TOR) in the soft tick Ornithodoros moubata (Acari: Argasidae)

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