calcimycin and acetylleucyl-leucyl-norleucinal

During adipocyte differentiation, the cells experience dramatic alterations in morphology, motility and cell-ECM contact. Focal adhesion kinase (pp125FAK), a widely expressed non-receptor tyrosine kinase in integrin signaling, has been reported to participate in these events in various cells. Utilizing 3T3-L1 cells and primary rat preadipocytes, we explored the role of FAK in adipocyte differentiation. Gradual cleavage of FAK was demonstrated during adipcoyte differentiation, both in vitro and in vivo. This cleavage of FAK was mediated by calpain. Inhibition of calpain activity resulted in the rescue of FAK degradation, accompanied with the disturbance of final maturation of adipocyte. Our study revealed that FAK participated in adipocyte differentiation, and its cleavage by calpain was required to fulfill the final maturation of adipocytes.

Topics: 3T3-L1 Cells; Adipocytes; Adipose Tissue; Animals; Blotting, Western; Calcimycin; Calpain; Cell Differentiation; Cell Nucleus; Cells, Cultured; Chromones; Cysteine Proteinase Inhibitors; Enzyme Inhibitors; Focal Adhesion Protein-Tyrosine Kinases; Ionophores; Leupeptins; Mice; Microscopy, Confocal; Morpholines; Peptide Fragments; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Rats; Signal Transduction; Time Factors

Extensive necrotic death of MSN neuroblastoma cells could be induced after incubation with the calcium ionophore, A23187. The reaction was concentration-dependent and time course-dependent. Levels of the 66 kd/alpha-internexin neurofilament protein (NF-66) and the cognate heat shock protein 70 (Hsc 70) decreased during the Ca2+-activated cell death. Addition of the calcium chelator, ethylene glycol-bis(beta-aminoethyl ether) N,N,N',N'-tetraacetic acid (EGTA) restored the normal level of NF-66 and partially that of the Hsc 70. Use of either calpain I or calpain II inhibitor could alleviate the reduction of 66 kd protein during the ionophore treatment whereas only calpain I inhibitor treatment was effective in restoring the normal level of the Hsc 70. Neither of these calpain inhibitors could block the ionophore triggered cell death. EGTA was toxic to cells in a wide range of concentration suggesting a calcium-independent activation of cell death mechanism.

Topics: Calcimycin; Calpain; Carrier Proteins; Cell Death; HSC70 Heat-Shock Proteins; HSP70 Heat-Shock Proteins; Humans; Intermediate Filament Proteins; Leupeptins; Nerve Tissue Proteins; Neuroblastoma; Neurofibrils; Oligopeptides; Tumor Cells, Cultured