Lysosomal Enzymes and their Receptors in Invertebrates: An Evolutionary Perspective

Abstract

Lysosomal biogenesis is an important process in eukaryotic cells to maintain cellular homeostasis. The key components that are involved in the biogenesis such as the lysosomal enzymes, their modifications and the mannose 6-phosphate receptors have been well studied and their evolutionary conservation across mammalian and non-mammalian vertebrates is clearly established. Invertebrate lysosomal biogenesis pathway on the other hand is not well studied. Although, details on mannose 6-phosphate receptors and enzymes involved in lysosomal enzyme modifications were reported earlier, a clear cut pathway has not been established. Recent research on the invertebrate species involving biogenesis of lysosomal enzymes suggests a possible conserved pathway in invertebrates. This review presents certain observations based on these processes that include biochemical, immunological and functional studies. Major conclusions include conservation of MPR-dependent pathway in higher invertebrates and recent evidence suggests that MPR-independent pathway might have been more prominent among lower invertebrates. The possible components of MPR-independent pathway that may play a role in lysosomal enzyme targeting are also discussed here.

Proteomic analysis of scallop hepatopancreatic extract provides insights into marine polysaccharide digestion

“…Both of these GO categories were dominated by glycoside hydrolases, sulfatases, proteinases and components of the proteasome, previously reported as lysosomal enzymes17 (Table 1). …”

Transcriptome Analysis of the Hepatopancreas in the Pacific White Shrimp (Litopenaeus vannamei) under Acute Ammonia Stress

“…vannamei [ 53 , 54 ]. It was reported that mannose-6-phosphate receptor involved in the immunological function in invertebrates [ 55 ]. Integrins are a family of adhesion receptors which regulate cell proliferation, differentiation, leukocyte migration, and complement receptor-dependent phagocytosis, and integrins β play an important role for the balanced activation of immune defense responses especially during the encounter of infections in L .…”

Proteolytic Characterization and Lysosomal Localization of Echinoderm Cathepsin D

“…The co-localization of both CIMPR and cathepsin D indicated that internalization and lysosomal transport was mediated by the receptor. In addition to the mannose 6-phoshate receptors, sortilin may play a role in lysosomal transport of this enzyme which needs to be validated with additional experiments [4,7]. However, previous reports of both the mannose 6-phosphate receptors in invertebrates such as echinoderms and mollusks indicates the lysosomal biogenesis in these organisms follows mannose 6-phosphate dependent pathways which is found to be evolutionarily conserved in higher vertebrates including mammals [21].…”

“…Both pathways act in synergy and one often complements in the absence of the other for the efficient lysosomal transport of cathepsin D. Both the receptors have been identified in mammals and putative homologs of the receptors responsible for the transport of lysosomal enzymes have been identified in echinoderms and mollusks [12]. Recent studies have reported the properties of lysosomal enzymes and their possible receptor-mediated lysosomal transport in invertebrates [7]. As the starfish cathepsin D has been affinity purified and preliminarily characterized [10], the present study was undertaken to gain new insights into two important properties of the enzyme (i) comparing its proteolytic activity against mammalian proteins and (ii) to study the MPR mediated lysosomal localization of the purified enzyme in mammalian cells.…”