Novel globular C1q domain-containing protein (PmC1qDC-1) participates in shell formation and responses to pathogen-associated molecular patterns stimulation in Pinctada fucata martensii

Abstract

The C1q protein, which contains the globular C1q (gC1q) domain, is involved in the innate immune response, and is found abundantly in the shell, and it participates in the shell formation. In this study, a novel gC1q domain-containing gene was identified from Pinctada fucata martensii (P. f. martensii) and designated as PmC1qDC-1. The full-length sequence of PmC1qDC-1 was 902 bp with a 534 bp open reading frame (ORF), encoding a polypeptide of 177 amino acids. Quantitative real-time PCR (qRT-PCR) result showed that PmC1qDC-1 was widely expressed in all tested tissues, including shell formation-associated tissue and immune-related tissue. PmC1qDC-1 expression was significantly high in the blastula and gastrula and especially among the juvenile stage, which is the most important stage of dissoconch shell formation. PmC1qDC-1 expression was located in the outer epithelial cells of mantle pallial and mantle edge and irregular crystal tablets were observed in the nacre upon knockdown of PmC1qDC-1 expression at mantle pallial. Moreover, the recombined protein PmC1qDC-1 increased the rate of calcium carbonate precipitation. Besides, PmC1qDC-1 expression was significantly up-regulated in the mantle pallial at 6 h and was significantly up-regulated in the mantle edge at 12 h and 24 h after shell notching. The expression level of PmC1qDC-1 in mantle edge was significantly up-regulated at 48 h after LPS stimulation and was significantly up-regulated at 12 h, 24 h and 48 h after poly I:C stimulation. Moreover, PmC1qDC-1 expression was significantly up-regulated in hemocytes at 6 h after lipopolysaccharide (LPS) and poly I:C challenge. These findings suggest that PmC1qDC-1 plays a crucial role both in the shell formation and the innate immune response in pearl oysters, providing new clues for understanding the shell formation and defense mechanism in mollusk.

Land snails can trap trematode cercariae in their shell: Encapsulation as a general response against parasites?

“…[4,8,10,16,19]) and cephalopods [11,12,18]. Moreover, genes involved in bivalve shell growth and biomineralisation are upregulated after immune challenge [26]. While to our knowledge, trematodes had not been implicated in shell-encapsulation mechanisms in gastropods, aquatic or terrestrial, until the present study, a pearl-like formation had been observed in the land snail Canistrum ovoideum (family Bradybaenidae) that could be of a pathological origin [2].…”

A Novel C1q Domain-Containing Protein Isolated from the Mollusk Modiolus kurilensis Recognizing Glycans Enriched with Acidic Galactans and Mannans

“…It is currently known that C1qDC proteins in the bivalve can be expressed in in all organs [8,16,17,20,37], especially in hepatopancreas [9,11,19,33], hemocytes [12,13,40], mantle [12,18] and gills [19]. However, transcription in hemocytes invariably increased upon immune stimulation.…”

“…Presumably, the abundance of C1qDC proteins allows covering the protective needs of the bivalve against various pathogens due to the potential structural diversity of PAMPs. Many bivalve C1qDC proteins are soluble, secreting PRRs that agglutinate and opsonize foreign agents by PAMPs recognizing [8][9][10][11][12], but several studies also have shown that they are involved in embryogenesis [9,10,13], shell formation [14][15][16] and interaction with predators [14]. Until recent years, some bivalve C1qDC proteins are classified either as lectins [8,[17][18][19] or as lectin-like proteins, which emphasizes their probable origin as lectins with subsequent diversification [2,7,20].…”

First Insights into the Repertoire of Secretory Lectins in Rotifers

“…For example, thanks to the carbohydrate-binding properties demonstrated in several metazoan phyla [68,69], C1qDC proteins should be regarded as PRRs involved in immune recognition. This role has been investigated in detail in Mollusca [70,71], where C1qDC proteins are associated with massive gene family expansions [34,35,72]. In bivalves, such expansions involve C1qDC proteins that either have a very simple architecture (signal peptide + C1q domain) or contain an additional N-terminal coiled-coil region.…”