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Cytoskeleton not only controls cell morphology but also regulates cell growth, migration, differentiation, and gene expression, events which are fundamental to embryogenesis, carcinogenesis, and wound healing. We have recently reported that reorganization of cytoskeleton induces expression of mRNA for transforming growth factor-beta 1 (TGF-beta 1), collagenase, and tissue inhibitor of metalloproteinase-I (TIMP-I) in dermal fibroblasts. In this report we have examined the role of gene transcription in this induction. As judged by nuclear run-on assay, trypsin, EGTA (ethylene glycol-bis (beta-aminoethyl ether) N, N, N', N', tetra-acetic acid), or cytochalasin C (Chs) increased the rate of transcription of the TGF-beta 1 gene by 2.0, 2.7, and 1.6 fold, respectively, and of the collagenase gene by 5.3, 6.2, and 3.3 fold. The rate of transcription of the TIMP-I gene was increased by trypsin (4.3 fold) or EGTA (3.8 fold) but unaffected by Chs. Cytochalasin induced an increase in the rate of transcription of procollagen I (alpha 1), procollagen I (alpha 2), and fibronectin genes by 1.4, 1.5, and 1.9 fold respectively, while trypsinization or EGTA treatment had no or little effects on these gene. Since transcription of the TGF-beta 1 gene is believed to be largely governed by the activating protein 1 (AP1) complex, we also examined the expression of mRNA for c-fos and c-jun protoon-coproteins. Trypsinization induced rapid (within 30 min) and transient expression of c-fos mRNA. A 2.4 fold increase in c-jun mRNA was apparent after 4 hr and persisted for at least 24 hr. Actinomycin D (Act D) suppressed the induction of TGF-beta 1 mRNA by Chs but had less effect on the TGF-beta 1 mRNA in trypsinized cells which had been replated for 4 hr, suggesting that the half life of TGF-beta 1 mRNA is reduced in cells with a disassembled cytoskeleton. Simultaneous treatment with Chs and cycloheximide (Cxm) resulted in a superinduction of TGF-beta 1 mRNA by 88 +/- 23% (n = 4, P < 0.05), which was abrogated by preexposure to Act D. In contrast, the induction of collagenase mRNA by Chs was totally blocked by Cxm, indicating that the Cxm-mediated superinduction is selective and that protein synthesis is required for induction of this mRNA. Our results suggest that the activities of genes for proteins involved in the structure (Type I collagen and fibronectin), turnover (collagenase and TIMP-1) and regulation (TGF-beta 1) of extracellular matrix (ECM), are all governed at least in part by the status of the cytoskeleton. Since the cytoskeleton is reorganized during cell division, migration, and differentiation, these results may have implications for the regulation of ECM during such processes as embryogenesis, carcinogenesis, and wound healing.

Type-1 diabetes (T1D) is a metabolic disorder associated with massive reduction in mass of adipose tissue. Measuring cell diameter, an index of fat metabolism, we determined depot-specific alterations in weight of adipose tissue, fat cell diameter and size heterogeneity and distribution at 5 depots in streptozotocin (STZ)-induced diabetic rats. T1D was induced by a single injection of STZ. Seven days after the injection, fat depots were isolated, weighted, washed and maintained in tissue culture medium. Using a microscope equipped with calibrated micrometer, cell diameter as well as size distribution pattern and heterogeneity of adipocytes were determined in fresh tissue slices of subcutaneous (SC), proximal epididymal (PE), distal epididymal (DE), perirenal (PR) and retroperitoneal (RP) fat depots. The T1D induced marked reductions in fat mass and mean of fat cell diameter at all depots. The most affected depot was the SC. With the exception of PE, adipocytes at all depots showed significant increases in size heterogeneity. The effect of the diabetes on mean fat cell diameter and size heterogeneity was minimal at PE depot. Depots with similar cell size distribution pattern exhibited similar fat mass reduction. However, the DE depot with a unique cell size distribution pattern showed a fat mass reduction similar to that of PE and PR depots. These data indicate that T1D induces a massive fat mass reduction in a reasonably depot-specific manner and that the fat depots close to survival organs are less vulnerable to fat mobilization. Moreover, peculiar disagreement between cell size distribution and heterogeneity as well as the level of fat mass reduction at DE and PE depots suggests that not only cell size and heterogeneity but also local factors may play roles in depot-specific fat mobilization.

of chronic diseases including obesity, metabolic syndrome, familial combined hyperlipidemia, tuberculosis, Crohn's disease, cancer-related chachexia, and diabetes; type-1 diabetes (T1D) in particular [ 4 , 6 , 7 ]. It is now accepted that positive correlation exists between the degree of lipolysis and the extent of disease-associated complications and that untreated lipolysis might account for risk of morbidity and mortality from the above mentioned diseases [ 7 ]. In T1D, insulin defi ciency and metabolic stressinduced elevation of catecholamines are known to be responsible for the activated lipolysis [ 6 ]. Not only insulin but also CP is defi cient in patients with T1D. Currently available information support the notion that co-replacement of insulin and CP in patients with T1D results in prevention or signifi cant amelioration of diabetes-induced abnormalities [ 8 ]. Several in vitro studies on biological actions and cell membrane binding kinetics have confi rmed that CP possesses physiological activities on its own [ 1 ]. In fact, CP can bind to its proposed pertussis toxin-sensitive G-protein-Affi liations Affi liation addresses are listed at the end of the article Affi liations

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