IUBMB Life, 54: 339–343, 2002 Copyright c  2002 IUBMB 1521-6543/02 $12.00 + .00 DOI: 10.1080/15216540290114694 Review Article Insect Inhibitors of Metalloproteinases Andreas Vilcinskas and Marianne Wedde Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany Summary Two types of peptidic metalloproteinase inhibitors have recently been identified in insects. A homologue of vertebrate tissue in- hibitors of metalloproteinases (TIMPs) was found in the fruitfly Drosophila melanogaster which may contributes to regulation of a corresponding matrix metalloproteinase (MMP). The first mem- ber of MMPs from insects which shares similarity with vertebrate MMPs has also been cloned and characterized from Drosophila, suggesting conserved evolution of both MMPs and TIMPs. The first insect inhibitor of metalloproteinases (IMPI), which was iden- tified in larvae of the greater wax moth, Galleria mellonella, shares no sequence similarity with known vertebrate or invertebrate pro- teins and represents the first non-TIMP-like inhibitor of metallo- proteinases reported to date. In contrast to TIMPs, the IMPI is not active against MMPs but inhibits microbial metalloproteinases such as bacterial thermolysin. Insects may recognize such toxic metalloproteinases associated with invading pathogens by particu- lar peptidic fragments that result from their nonregulated activity within the hemolymph. Metalloproteinases induce expression of the IMPI along with other antimicrobial proteins in course of humoral immune response of G. mellonella, thereby mediating regulation of metalloproteinase activity released within the hemolymph and inhibition of pathogen development as well. IUBMB Life, 54: 339–343, 2002 Keywords Drosophila melanogaster; Galleria mellonella; immu- nity; insects; metalloproteinases; proteinase regulation; tissue inhibitors of metalloproteinases. INTRODUCTION Insects exhibit the highest evolutionary success regarding species diversity and have been established as powerful models in molecular biology and biochemistry. Particularly, the fruit- fly Drosophila melanogaster represents an outstanding tool in Received 12 September 2002; accepted 24 October 2002. Address correspondence to Andreas Vilcinskas, Institute of Bio- chemistry and Biology, University of Potsdam, Lennestr. 7a, D-14471 Potsdam, Germany. Fax: +49 331 977 4861; E-mail: vilcinsk@ rz-unipotsdam.de Abbreviations: TIMP, tissue inhibitor of matrix metalloproteinase; MMP, matrix metalloproteinase; IMPI, insect metalloproteinase inhibitor. comparative molecular analysis of genes and gene function. The number of homologous genes and signaling pathways, first iden- tified in Drosophila and then vertebrates or vice versa, is rapidly growing. The tremendous progress in the research of evolution- ary conserved molecules and mechanisms was initiated by and profited from the principle of mutual elucidation. Consequently, comparative molecular biology and biochemistry between in- sects and vertebrates has become a productive research field. This review focuses on two recently discovered insect metallo- proteinase inhibitors. The first section addresses the identification of the first TIMP and MMP member in insects. The determined sequence of both genes found in Drosophila exhibit homology with vertebrate MMPs and TIMPs. The second section reviews the research on the insect metalloproteinase inhibitor (IMPI), which has been identified in larvae of the greater wax moth, Galleria mellonella. The latter represents the first inhibitor of metalloproteinases reported from insects and the first non-TIMP-like peptidic in- hibitor of metalloproteinases known to date. In the last section we will introduce a novel mechanism mediating recognition and inhibition of nonregulated endogenous or microbial metallopro- teinases in the hemolymph of insects and its transferability to vertebrate models. Tissue Inhibitor of Matrix Metalloproteinases from Drosophila Tissue inhibitors of metalloproteinases (TIMPs) from verte- brates attracted great attention during past decade due to their multifaceted roles associated with the regulation of matrix met- alloproteinases. The latter are essential for extracellular matrix degradation during development and morphogenesis. Particu- larly, they mediate resorption and remodeling of the extracellular matrix (1–3). Imbalanced MMP activity accompanies a variety of pathologic developments or diseases such as tumor progres- sion and metastasis formation. Twenty-five members of MMPs and 4 TIMPs have so far been reported from vertebrates (4, 5). Regarding the tremendous amount of publications dealing with vertebrate MMPs and TIMPs, which appeared during past decades and have been extensively reviewed, it is surprising that 339