SPECIFIC DEVELOPMENTAL-CHANGES IN THE REGULATORY SUBUNITS OF THE 26-SPROTEASOME IN INTERSEGMENTAL MUSCLES PRECEDING ECLOSION IN MANDUCA-SEXTA

Previously, we have shown extensive reprogramming of the ATPase regula tor of the 26X proteasome preceding the programmed destruction of inte rsegmental muscles (ISM) in the tobacco horn moth Manduca sexta (Dawso n et al., J. Biol. Chem., 270, 1850-1858, 1995). We now show that the extensive reprogramming of the regulatory components of the 26S protea some occurs only in ISM and not in flight muscles (FM), which undergo terminal differentiation at ecdysis. Unlike in ISM, the ATPase regulat ors, MS73, MSS1, TBP1 and mts2, remain at low levels in 268 proteasome s in FM from developmental Stage-0 to Stage-7. The non-ATPase regulato r subunit 5a, which binds to multiubiquitin chains, increased in ISM s imilarly to the ATPases but not in FM. The ecdysteroid agonist RH-5849 prevented these subunit increases in ISM. These findings show that re programming of 26 S proteasomes is involved in the specific eliminatio n of ISM during eclosion and does not occur in FM which are needed for adult moth flight. (C) 1996 Academic Press, Inc.