In this project we propose to study the mechanism and control of myofibrillar and mitochondrial assembly and degradation during the transition of the myocardium between two steady states. The proteins which turnover with heterogeneous rates will be studied. The main objectives are: 1. To determine whether the rate of synthesis (Rs) or the fractional rate turnover (kp) change during various phases of growth. Considering the heterogeneous nature of the turnover of proteins one of the rates necessarily must be changing during growth in order to maintain a constant ratio of individual proteins within the organelle. 2. To characterize myosin HC under conditions leading to altered ATPase activity. The putative isoenzymes will be characterized with respect to amino acid sequence (limited fragmentation) and immunological properties. The Rs and kp of separated HC will be measured during transition from one isoenzyme pattern to another one. 3. To determine whether the relative fractional rates of turnover of structural proteins and those of the soluble proteins are changed during accelerated degradation. Proteins will be evaluated with respect to molecular weight, isoelectric point, and carbohydrate content. 4. The role of calcium-activated neutral protease (CaAp) in the turnover of myofibrils will be reexamined. The cellular origin of CaAp will be determined by immunofluorescence. Turnover of myosin HC and alpha-actinin will be determined in cultured heart cells after calcium influx is enhanced by an ionophore. The stability of the double hexagonal lattice of myofilaments will be examined after alpha-actinin removal. 5. To study the involvement of lysosomal proteases in the degradation of myofibrils. Attempts will be made to detect myosin or its high molecular-weight degradation products in the lysosomal fraction prepared from muscle.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL016637-12
Application #
3335240
Study Section
Biochemistry Study Section (BIO)
Project Start
1977-05-01
Project End
1990-04-30
Budget Start
1986-05-01
Budget End
1987-04-30
Support Year
12
Fiscal Year
1986
Total Cost
Indirect Cost
Name
University of Chicago
Department
Type
Schools of Medicine
DUNS #
225410919
City
Chicago
State
IL
Country
United States
Zip Code
60637
Toyofuku, T; Hoffman, J R; Zak, R et al. (1992) Expression of alpha-cardiac and alpha-skeletal actin mRNAs in relation to innervation in regenerating and non-regenerating rat skeletal muscles. Dev Dyn 193:332-9
Wiesner, R J; Zak, R (1991) Quantitative approaches for studying gene expression. Am J Physiol 260:L179-88
Hood, D A (1990) Co-ordinate expression of cytochrome c oxidase subunit III and VIc mRNAs in rat tissues. Biochem J 269:503-6
Zak, R; Camoretti-Mercado, B; Gupta, M et al. (1990) Myofibrillar proteins in the developing heart. Ann N Y Acad Sci 588:216-24
Maier, A; Zak, R (1990) Presence in chicken tibialis anterior and extensor digitorum longus muscle spindles of reactive and unreactive intrafusal fibers after incubation with monoclonal antibodies against myosin heavy chains. Am J Anat 187:338-46
Maier, A; Zak, R (1990) Arrangement of cytoskeletal filaments at the equator of chicken intrafusal muscle fibers. Histochemistry 93:423-8
Gregory, P; Gagnon, J; Essig, D A et al. (1990) Differential regulation of actin and myosin isoenzyme synthesis in functionally overloaded skeletal muscle. Biochem J 265:525-32
Stewart, A F; Kennedy, J M; Bandman, E et al. (1989) A myosin isoform repressed in hypertrophied ALD muscle of the chicken reappears during regeneration following cold injury. Dev Biol 135:367-75
Reid, S K; Kennedy, J M; Shimizu, N et al. (1989) Regulation of expression of avian slow myosin heavy-chain isoforms. Biochem J 260:449-54
Gagnon, J; Kurowski, T T; Zak, R (1989) Synthesis and assembly of native myosin on muscle polyribosomes. FEBS Lett 250:549-55

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