Insectivorous Bats Digest Chitin in the Stomach Using Acidic Mammalian Chitinase

Strobel, Sara; Roswag, Anna; Becker, Nina I.; Trenczek, Tina; Encarnação, Jorge A.

doi:10.1371/journal.pone.0072770

Cited by 56 publications

(52 citation statements)

References 30 publications

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“…Indeed, a prominent role for AMCase in the stomach and duodenum is expected because its chitinolytic activity is greatest at low pH. AMCase functions as a true chitinase in the stomach, as previously suggested 28 ; therefore, it is quickly transported into the duodenum, where it may aid in the disruption, release, and/or processing of parasite-associated chitinous antigens that are critical for the initiation of protective type 2 responses in the gut. We found no evidence that the defective type 2 responses observed during nematode infection were T cell intrinsic.…”

Section: Discussionmentioning

confidence: 73%

Acidic chitinase primes the protective immune response to gastrointestinal nematodes

et al. 2016

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Acidic mammalian chitinase (AMCase) is known to be induced by allergens and helminths, yet its role in immunity is unclear. Using AMCase-deficient mice, we show that AMCase deficiency reduced the number of group 2 innate lymphoid cells during allergen challenge but was not required for establishment of type 2 inflammation in the lung in response to allergens or helminths. In contrast, AMCase-deficient mice showed a profound defect in type 2 immunity following infection with the chitin-containing gastrointestinal nematodes Nippostrongylus brasiliensis and Heligmosomoides polygyrus bakeri. The impaired immunity was associated with reduced mucus production and decreased intestinal expression of the signature type 2 response genes Il13, Chil3, Retnlb, and Clca1. CD103+ dendritic cells, which regulate T cell homing, were also reduced in mesenteric lymph nodes of infected AMCase-deficient mice. Thus, AMCase functions as a critical initiator of protective type 2 responses to intestinal nematodes but is largely dispensable for allergic responses in the lung.

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Section: Discussionmentioning

confidence: 73%

Acidic chitinase primes the protective immune response to gastrointestinal nematodes

et al. 2016

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“…Wild mice eat chitin containing foods such as insects, whereas laboratory mice are fed artificial diets containing dried brewers’ yeast, which also contains chitin in the cell wall. AMCase has also been found in insectivorous bats, which eat arthropods containing chitin38. Bat AMCase is synthesized in the stomach chief cells and it is most active at bat stomach environment (highest between pH 5.0 and pH 6.0)38.…”

Section: Discussionmentioning

confidence: 99%

Acidic mammalian chitinase is a proteases-resistant glycosidase in mouse digestive system

Ohno

Kimura

Miyazaki

et al. 2016

Sci Rep

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Chitinases are enzymes that hydrolyze chitin, a polymer of β-1, 4-linked N-acetyl-D-glucosamine (GlcNAc). Chitin has long been considered as a source of dietary fiber that is not digested in the mammalian digestive system. Here, we provide evidence that acidic mammalian chitinase (AMCase) can function as a major digestive enzyme that constitutively degrades chitin substrates and produces (GlcNAc)2 fragments in the mouse gastrointestinal environment. AMCase was resistant to endogenous pepsin C digestion and remained active in the mouse stomach extract at pH 2.0. The AMCase mRNA levels were much higher than those of four major gastric proteins and two housekeeping genes and comparable to the level of pepsinogen C in the mouse stomach tissues. Furthermore, AMCase was expressed in the gastric pepsinogen-synthesizing chief cells. The enzyme was also stable and active in the presence of trypsin and chymotrypsin at pH 7.6, where pepsin C was completely degraded. Mouse AMCase degraded polymeric colloidal and crystalline chitin substrates in the gastrointestinal environments in presence of the proteolytic enzymes. Thus, AMCase can function as a protease-resistant major glycosidase under the conditions of stomach and intestine and degrade chitin substrates to produce (GlcNAc)2, a source of carbon, nitrogen and energy.

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“…Chitin can be digested only with chitinase and acidic mammalian chitinase ( AMCase ); AMCase is widely found in the digestive organs of animals (Eurich et al, 2009; Krykbaev et al, 2010; Strobel et al, 2013). The origin of the digestive processes might be closely related to the activity of AMCase , which determines the beginning of chitin.…”

Section: Discussionmentioning

confidence: 99%

“…Chitin is a linear polymer of N-acetyl-beta-glucosaminidase subunits linked by a beta-1, 4 glycosidic bond and is one of the constituents of insect exoskeletons and the peritrophic membranes of ants (Kawashima et al, 2016). The internal degradation of chitin particles is mainly catalyzed by chitinase (Strobel et al, 2013). …”

Section: Introductionmentioning

confidence: 99%

Transcriptomic analysis identifies genes and pathways related to myrmecophagy in the Malayan pangolin (Manis javanica)

Ma¹,

Li²,

Jiang³

et al. 2017

PeerJ

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The Malayan pangolin (Manis javanica) is an unusual, scale-covered, toothless mammal that specializes in myrmecophagy. Due to their threatened status and continuing decline in the wild, concerted efforts have been made to conserve and rescue this species in captivity in China. Maintaining this species in captivity is a significant challenge, partly because little is known of the molecular mechanisms of its digestive system. Here, the first large-scale sequencing analyses of the salivary gland, liver and small intestine transcriptomes of an adult M. javanica genome were performed, and the results were compared with published liver transcriptome profiles for a pregnant M. javanica female. A total of 24,452 transcripts were obtained, among which 22,538 were annotated on the basis of seven databases. In addition, 3,373 new genes were predicted, of which 1,459 were annotated. Several pathways were found to be involved in myrmecophagy, including olfactory transduction, amino sugar and nucleotide sugar metabolism, lipid metabolism, and terpenoid and polyketide metabolism pathways. Many of the annotated transcripts were involved in digestive functions: 997 transcripts were related to sensory perception, 129 were related to digestive enzyme gene families, and 199 were related to molecular transporters. One transcript for an acidic mammalian chitinase was found in the annotated data, and this might be closely related to the unique digestive function of pangolins. These pathways and transcripts are involved in specialization processes related to myrmecophagy (a form of insectivory) and carbohydrate, protein and lipid digestive pathways, probably reflecting adaptations to myrmecophagy. Our study is the first to investigate the molecular mechanisms underlying myrmecophagy in M. javanica, and we hope that our results may play a role in the conservation of this species.

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Insectivorous Bats Digest Chitin in the Stomach Using Acidic Mammalian Chitinase

Cited by 56 publications

References 30 publications

Acidic chitinase primes the protective immune response to gastrointestinal nematodes

Acidic chitinase primes the protective immune response to gastrointestinal nematodes

Acidic mammalian chitinase is a proteases-resistant glycosidase in mouse digestive system

Transcriptomic analysis identifies genes and pathways related to myrmecophagy in the Malayan pangolin (Manis javanica)

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