Identification of novel lumbricin homologues in Eisenia andrei earthworms

Abstract

Lumbricin and its orthologue antimicrobial peptides were typically isolated from annelids. In this report, mRNA for lumbricin and -serendipitously- a novel lumbricin-related mRNA sequence were identified in Eisenia andrei earthworms. The determined mRNA sequences of E. andrei lumbricin and lumbricin-related peptide consist of 477 and 575 nucleotides. The precursors of proline-rich E. andrei lumbricin and the related peptide contain 63 and 59 amino acids, respectively. Phylogenetic analysis indicated close relationship with other annelid lumbricins. Highest expression of both mRNAs appeared in the proximal part of the intestine (pharynx, gizzard), while other tested organs had moderate (body wall, midgut, ovary, metanephridium, seminal vesicles, ventral nerve cord) or low (coelomocytes) levels. During ontogenesis their expression revealed continuous increase in embryos. Following 48 h of in vivo Gram-positive bacteria challenge both mRNAs were significantly elevated in coelomocytes, while Gram-negative bacteria or zymosan stimulation had no detectable effects.

Bacterial Engulfment Mechanism Is Strongly Conserved in Evolution Between Earthworm and Human Immune Cells

“…Earthworms, living in a microbe-rich environment, are constantly exposed to bacteria; their immune homeostasis is governed by several cellular and humoral components (23)(24)(25). Recent publications are more focused on the variations of immune-related genes upon microbial challenge in earthworms (26,27). However, the different cellular engulfment routes to eliminate microbes by coelomocytes are rather unknown in earthworms, similarly to other invertebrate models.…”

Injury-Induced Innate Immune Response During Segment Regeneration of the Earthworm, Eisenia andrei

“…Regenerating E. andrei revealed markedly lower expression of evolutionarily conserved lysozyme compared to intact earthworms (Figure 9a,b), however, oneweek posterior blastema (Figure 9b) showed an elevated lysozyme mRNA level. Recently, we identified and characterized the proline-rich lumbricin and its close-relative molecule (LuRP) in E. andrei earthworms [58]. The medicinal leech microbial challenge enhanced lumbricin and neuromacin expression, which most probably promoted neuronal regeneration [30].…”

Worms’ Antimicrobial Peptides

“…Lumbricins are proline-rich AMPs characterized in oligochaete earthworms Lumbricus rubellus (lumbricin-1), Pheretima tschiliensis (PP-1), P. guillelmi (lumbricin-PG), and Eiseinia andrei (Lumbr and LuRP), and in the leech H. medicinalis (Hm-lumbricin) [42,43,128,129,130], but also found in polychaetes such as the Pompeii worm A. pompejana (AT & DJ, pers. obs.)…”

“…Lumbricin-1 exhibits antibacterial activity towards a broad spectrum of Gram-positive and Gram-negative bacteria and fungi (Table 3) [42,43,128,129,130], but their MOA is still unknown. PP-1 is synthesized in the mucus of the epidermis; the two lumbricins from E. andrei have been detected in the intestine and in other tissues (body wall, gut, ovary, etc.)…”

“…[43,128,131,132]. Interestingly, Hm-lumbricin gene expression is rapidly enhanced by bacterial challenge [43], whereas Lumbr and LuRP are slowly induced (after 48 h) following the infection [129]. By contrast, lumbricin-1 (present only in adult worms) is not inducible when the animal is subjected to a bacterial challenge [42].…”