IMAGINAL CELL-SPECIFIC ACCUMULATION OF THE MULTICATALYTIC PROTEINASE COMPLEX (PROTEASOME) DURING POSTEMBRYONIC DEVELOPMENT IN THE TOBACCO HORNWORM, MANDUCA-SEXTA

The multicatalytic proteinase complex is a multi-subunit, high molecul ar weight proteinase present in the nucleus and cytoplasm of eukaryoti c cells. This catalytic complex is involved in diverse cellular functi ons as part of the ubiquitin proteolysis system, including nonlysosoma l proteolysis, antigen presentation, cell cycle progression, and cell proliferation, and in the programmed death of intersegmental muscles a fter adult eclosion in the tobacco hornworm moth, Manduca sexta. We ha ve investigated the distribution of the multicatalytic proteinase comp lex in the central nervous system of this moth. At all stages of post- embryonic development, most cell types exhibited consistent, low level s of cytoplasmic and nuclear immunoreactivity for the multicatalytic p roteinase complex. High levels of cell-specific accumulation of the co mplex were, however, demonstrated in abdominal neurosecretory cells an d in imaginal cells in the larval brain, the larval segmental ganglia, and the developing wing discs. Imaginal cells exhibited intense immun oreactivity for the multicatalytic proteinase complex only until the o nset of terminal differentiation. Intersegmental muscles undergoing pr ogrammed cell death exhibited intense cytoplasmic immunoreactivity for the multicatalytic proteinase, while persisting flight muscles and dy ing neurons were characterized by basal levels of staining. These stai ning patterns suggest that the multicatalytic proteinase of Manduca se xta serves multiple functions and Is associated with the period of dev elopmental arrest displayed by imaginal cells prior to metamorphosis. (C) 1996 Wiley-Liss, Inc.