The insect immune protein hemolin is expressed during oogenesis and embryogenesis

Abstract

Hemolin is the most abundant bacteria-induced proteins in Hyalophora cecropia hemolymph. Its structural features, both at the protein and gene level, ascribe this molecule to the immunoglobulin gene superfamily (IgSF) with particular homology to neural cell adhesion molecules. An increasing number of evidence suggest a role in immune recognition and in cell adhesion events. Hemolin is also developmentally regulated as suggested by changes in its concentration during larval and pupal ecdysis (Trenczek, T., 1998. Endogenous defense mechanisms of insects. Zoology 101, 298-315; Lanz-Mendoza, H., Faye, I., 1999. Physiological aspects of the immunoglobulin superfamily in invertebrates. Dev. Comp. Immunol. 23, 359-374). In the present study the expression of hemolin was investigated in oogenesis and in early embryogenesis. Our results reveal that hemolin is expressed in follicles and in epidermal and neural tissues of embryos.

EST-based profiling and comparison of gene expression in the silkworm fat body during metamorphosis

“…5; Table 2), and these observations were not in agreement with previous reports that hemolin was abundantly expressed in larva (Lanz-Mendoza et al, 1996). Therefore, it is reasonable to suggest that hemolin plays a broader role from pupa to adult, perhaps also being involved in the normal development of oocytes and embryos, as that has been investigated previously in other insects (Bettencourt et al, 2000(Bettencourt et al, , 2002. Stan encodes the protocadherin-like wing polarity protein and participates in the fz (frizzled) signaling pathway responsible for controlling wing tissue polarity (Usui et al, 1999), which also initiates prehair morphogenesis and regulates tissue polarity and formation of normal dendrite fields (Chae et al, 1999).…”

Losac, the First Hemolin that Exhibits Procogulant Activity through Selective Factor X Proteolytic Activation

“…Due to its adhesion properties, some hemolins have been involved in the cell adhesion mechanism (37). Some studies reveal that hemolins are present in neural tissues in several phases of embryonic development (24), and their expression correlates with hormones that regulate moulting and metamorphosis of lepidopters (19,45). It seems clear that hemolins are multifunctional proteins with roles in defense (cellular and humoral) and in development (22).…”

“…Hemolin is a bacteria-inducible immunoglobulinlike protein whose role in insect immunity has been better studied. In the last 2 decades, independent studies have demonstrated that hemolin proteins are multifunctional molecules involved in a diverse range of cell interaction and are able to (a) bind lipopolysaccharides and be up-regulated in hemolymph during infections (15)(16)(17); (b) be up-regulated during metamorphosis (18,19); (c) promote opsonin-like effects, such as increased cell adhesion and phagocytosis (20,21); (d) agglutinate bacterial cells (17,22); (e) bind to hemocytes and inhibit their aggregation (15,20,22,23); and (f) regulate embryonic development (24,25).…”

Binding of hemolin to bacterial lipopolysaccharide and lipoteichoic acid. An immunoglobulin superfamily member from insects as a pattern-recognition receptor

“…A hemolinlike cDNA was also cloned from the fall webworm, Hyphantria cunea [9]. Hemolin is synthesized mainly in fat body in response to microbial challenge [4,8], but it is also synthesized in the absence of infection in embryos [10] and in fat body and midgut during metamorphosis [3,11,12]. Hemolin expressed at different developmental stages of M. sexta differs in carbohydrate content.…”