Detection of DNA fragmentation and apoptotic proteins, and quantification of uncoupling protein expression by real-time RT-PCR in adipose tissue

DNA analysis of cattle parasitic protozoan Tritrichomonas foetus after photodynamic therapy

Photodynamic therapy (PDT) is a modality of therapy that involves the activation of photosensitive substances and the generation of cytotoxic oxygen species and free radicals to promote the selective destruction of target tissues. This study analyzed the application of PDT to Tritrichomonas foetus, a scourged and etiological agent of bovine trichomoniasis, a sexually transmitted infectious disease. As it is an amitochondrial and aerotolerant protozoan, it produces energy under low O₂ tension via hydrogenosome. T. foetus from an axenic culture was incubated with photosensitizer tetrasulfonated aluminium phthalocyanine and then irradiated with a laser source (InGaAIP) at a density of 4.5Jcm^-2. The DNA integrity of the control and treated group parasites was analyzed by conventional gel electrophoresis and comet assay techniques. In previous results, morphological changes characterized by apoptotic cell death were observed after T. foetus was submitted to PDT treatment. In the treated groups, T. foetus DNA showed a higher concentration of small fragments, about 200pb, in gel electrophoresis after PDT. In the comet assay, the DNA tail percentage was significantly higher in the treated groups. These results demonstrate that PDT leads to DNA fragmentation with changes in nuclear morphology and apoptotic features.

The use of adipose tissue-conditioned media to demonstrate the differential effects of fat depots on insulin-stimulated glucose uptake in a skeletal muscle cell line

SUMMARY

We aimed to study the depot-specific effect of adipose tissue on insulin sensitivity of skeletal muscle in vitro. Adipose tissue-conditioned medium (CM) was generated from visceral and subcutaneous fat from obese subjects. CM from visceral as compared to subcutaneous fat had higher concentrations of interleukin (IL)-6 (15-fold; P < 0.05) and IL-8 (8-fold; P < 0.05). CM from visceral fat (1:128 dilution) reduced insulin-stimulated glucose uptake in L6 myotubes by 19% (P < 0.05), an effect mediated by a nuclear factor kappa B (NFκB)/mammalian target of rapamycin complex 1 (mTORC1)-dependent pathway and partially reversed by neutralizing IL-6. IL-6 at a concentration comparable to that in CM from visceral fat reduced insulin-stimulated glucose uptake by 53% (P < 0.05), an effect abolished by inhibiting NFκB or mTORC1. We demonstrated the utility of the CM-myotube system and identified IL-6 as a major cytokine mediating visceral fat-induced muscle insulin resistance.:

Comparison of three detergent-free protein extraction protocols for white adipose tissue

A comparative study of three detergent-free protein extraction protocols--a differential centrifugal fractionation, a delipidation protocol based on the Bligh and Dyer method, and the trifluoroethanol addition as cosolvent to an aqueous buffer--was performed on white adipose tissue. The performance of the protocols directly compatible with liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) was evaluated based on the total protein extraction yield and the protein recovery from different functional and cellular compartments. The most suitable method for the extraction of white adipose tissue proteins from a wide range of cellular and structural compartments was the delipidation protocol based on the Bligh and Dyer method.

Involvement of various molecular events in cellular injury induced by smokeless tobacco

Smokeless tobacco (ST) consumption is implicated in the pathogenesis of oral diseases, including cancer. However, its pathological effect in other organs is not well understood. In the present study, the effect of aqueous extract of smokeless tobacco (AEST) prepared from "gutkha" (a form of ST) on the xenobiotic drug-metabolizing enzymes, histopathological changes, and damage to the genetic material in lung, liver, and kidney of rats was evaluated. Animals were orally administered AEST at a low dose (L-AEST, 96 mg/kg body wt/day) for 2 (L-AEST(2)) and 28 weeks (L-AEST(28)) and at a high dose (H-AEST, 960 mg/kg body wt/day) for 2 weeks (H-AEST(2)). Real-time PCR and immunohistological studies showed that administration of L-AEST(2) did not induce the expression of phase I cytochrome P450s (CYP1A1, 1A2, and 2E1) and phase II mu-glutathione-s-transferase (GST-mu) drug-metabolizing enzymes in lung, liver, and kidney. Although H-AEST(2) administration significantly induced both gene and protein expression of CYP1A1, 1A2, and 2E1 in all of the above organs, it mildly expressed the phase II detoxifying enzyme, GST-mu, in type I and type II epithelial cells of lung and in proximal tubular cells of kidney. L-AEST(28) enhanced the gene and protein expression of CYP1A1, 1A2, and 2E1 in lung, liver, and kidney in a differential manner and induced the expression of GST-mu in lung and kidney. L-AEST(28) induced the micronuclei formation in the peripheral blood mononuclear cells, TNF-alpha in plasma, and myeloperoxidase activity in the organs. L-AEST(28) significantly enhanced Bax, p53, and NF-kappaB and decreased Bcl-2 gene expressions differentially in an organ-specific manner. The differential changes in these organs due to AEST might be due to their different physiological functions and variable sensitivities toward the metabolites of AEST, which create a microenvironment favorable for AEST-induced pathogenesis. This study broadens the insight into the different molecular mechanisms in various organs, which appear to be deregulated due to AEST. Understanding these processes may help in clinical treatment planning strategies for tobacco-related diseases.

Ciliary neurotrophic factor infused intracerebroventricularly shows reduced catabolic effects when linked to the TAT protein transduction domain

Ciliary neurotrophic factor (CNTF) regulates the differentiation and survival of a wide spectrum of developing and adult neurons, including motor neuron loss after injury. We recently described a cell-penetrant recombinant human CNTF (rhCNTF) molecule, formed by fusion with the human immunodeficiency virus-1 transactivator of transcription (TAT) protein transduction domain (TAT-CNTF) that, upon subcutaneous administration, retains full neurotrophic activity without cytokine-like side-effects. Although the CNTF receptor is present in hypothalamic nuclei, which are involved in the control of energy, rhCNTF but not TAT-CNTF stimulates signal transducers and activators of transcription 3 phosphorylation in the rat hypothalamus after subcutaneous administration. This could be due limited TAT-CNTF distribution in the hypothalamus and/or altered intracellular signaling by the fusion protein. To explore these possibilities, we examined the effect of intracerebroventricular administration of TAT-CNTF in male adult rats. TAT-CNTF-induced weight loss, although the effect was smaller than that seen with either rhCNTF or leptin (which exerts CNTF-like effects via its receptor). In contrast to rhCNTF and leptin, TAT-CNTF neither induced morphological changes in adipose tissues nor increased uncoupling protein 1 expression in brown adipose tissue, a characteristic feature of rhCNTF and leptin. Acute intracerebroventricular administration of TAT-CNTF induced a less robust phosphorylation of signal transducers and activators of transcription 3 in the hypothalamus, compared with rhCNTF. The data show that fusion of a protein transduction domain may change rhCNTF CNS distribution, while further strengthening the utility of cell-penetrating peptide technology to neurotrophic factor biology beyond the neuroscience field.

Gender-specific effects of HIV protease inhibitors on body mass in mice

Protease inhibitors, as part of highly active anti-retroviral therapy (HAART), have significantly increased the lifespan of human immunodeficiency virus (HIV) infected patients. Several deleterious side effects including dyslipidemia and lipodystrophy, however, have been observed with HAART. Women are at a higher risk of developing adipose tissue alterations and these alterations have different characteristics as compared to men. We have previously demonstrated that in mice the HIV protease inhibitor, ritonavir, caused a reduction in weight gain in females, but had no effect on male mice. In the present study, we examined the potential causes of this difference in weight gain. Low-density lipoprotein receptor (LDL-R) null mice or wild-type C57BL/6 mice, were administered 15 mug/ml ritonavir or vehicle (0.01% ethanol) in the drinking water for 6 weeks. The percent of total body weight gained during the treatment period was measured and confirmed that female LDL-R gained significantly less weight with ritonavir treatment than males. In wild type mice, however, there was no effect of ritonavir treatment in either sex. Despite the weight loss in LDL-R null mice, ritonavir increased food intake, but no difference was observed in gonadal fat weight. Serum leptin levels were significantly lower in females. Ritonavir further suppressed leptin levels in (p < 0.05). Ritonavir did not alter serum adiponectin levels in either gender. To determine the source of these differences, female mice were ovariectomized remove the gonadal sex hormones. Ovariectomy prevented the weight loss induced by ritonavir (p < 0.05). Furthermore, leptin levels were no longer suppressed by ritonavir (p < 0.05). This study demonstrates that gonadal factors in females influence the hormonal control of weight gain changes induced by HIV protease inhibitors in an environment of elevated cholesterol.

Injections of leptin into rat ventromedial hypothalamus increase adipocyte apoptosis in peripheral fat and in bone marrow

The accumulation of fat cells (adipocytes) in bone marrow is now thought to be a factor contributing to age-related bone loss. Women with osteoporosis have higher numbers of marrow adipocytes than women with healthy bone, and bone formation rate is inversely correlated with adipocyte number in bone tissue biopsies from both men and women. Adipogenic differentiation of bone marrow stromal cells increases with age, but the factors regulating populations of mature adipocytes are not well understood. Leptin is thought to regulate adipose tissue mass via its receptors in the ventromedial hypothalamus (VMH). We have therefore tested the hypothesis that stimulation of leptin receptors in the VMH regulates adipocyte number in bone marrow. Results indicate that unilateral twice-daily injections of leptin into the rat VMH for only 4 or 5 days cause a significant reduction in the number of adipocytes in peripheral fat pads and bone marrow and indeed eliminate adipocytes almost entirely from bone marrow of the proximal tibia. Osteoblast surface is not affected with leptin treatment. Apoptosis assays performed on bone marrow samples from control and treated rats have revealed a significant increase in protein concentration of the apoptosis marker caspase-3 with leptin treatment. We conclude that stimulation of leptin receptors in the VMH significantly decreases the adipocyte population in bone marrow, primarily through apoptosis of marrow adipocytes. Elimination of marrow adipocytes via this central pathway may represent a useful strategy for the treatment and prevention of osteoporosis.

Genistein decreases food intake, body weight, and fat pad weight and causes adipose tissue apoptosis in ovariectomized female mice

Genistein, an isoflavone in soybean products, has estrogenic activity and is used as a natural substitute for estrogen replacement therapy in postmenopausal women. Genistein was also shown to decrease fat pad weight in female mice. The primary objective of this study was to determine the effect of genistein on adipose tissue apoptosis in vitro and in vivo. 3T3-L1 preadipocytes and mature adipocytes were treated with 0, 1, 10, 100, and 400 micromol/L genistein and then assayed for apoptosis, whereas only mature adipocytes were assayed for viability. Mature adipocytes treated with genistein demonstrated a dose-related increase in apoptosis. Ovariectomized female mice (9 mo old) were given 0, 150, or 1,500 mg/kg genistein in the semipurified phytoestrogen-free casein-based diet for 3 wk (n=10). After mice were killed, body composition was determined by dual-energy X-ray absorptiometry analysis, and parametrial (PM), inguinal (ING), and retroperitoneal (RP) fat pads were weighed and assayed for apoptosis (% DNA fragmentation). Genistein (1500 mg/kg) reduced food intake (FI) by 14% (P<0.01) and body weight (BW) by 9% (P<0.01). Body composition was not significantly affected, but PM and ING weights were decreased 22% (P<0.05) and 19% (P<0.07), respectively, by 1,500 mg/kg genistein. Apoptosis in ING fat was increased 290% (P<0.05) by 1,500 mg/kg genistein. These findings show that oral genistein treatment can reduce BW, mobilize body fat, and induce apoptosis of adipose tissue in ovariectomized female mice. Thus, genistein may be useful in treating or preventing increased adiposity after menopause.

Sensitivity of ob/ob mice to leptin-induced adipose tissue apoptosis

OBJECTIVE

ob/ob mice have increased sensitivity to many of leptin's effects. The primary objective of this experiment was to determine whether ob/ob mice demonstrated increased sensitivity to leptin-induced adipose tissue apoptosis.

RESEARCH METHODS AND PROCEDURES

Fifteen-week-old female ob/ob and Ob/? mice received 0 (saline), 2.5, or 10 microg/d leptin for 14 days through subcutaneous (sc) osmotic minipumps. Food intake (FI), body temperature, physical activity, and body weight were measured daily. Body composition and weights and adipose tissue apoptosis (percentage DNA fragmentation) of inguinal, parametrial, and retroperitoneal fat pads were determined at the end of the study.

RESULTS

FI decreases were more pronounced in ob/ob. Leptin (10 microg/d) decreased total FI 71% in ob/ob and 34% in Ob/? (p < 0.05). Body weight was decreased by both doses of leptin in ob/ob (p < 0.01) but was unchanged in Ob/?. Leptin increased body temperature in ob/ob but not in Ob/?. Physical activity was increased 400% by 10 microg/d leptin in ob/ob (p < 0.01) but decreased 13% in Ob/? (p < 0.01). Body fat content of ob/ob was reduced by both leptin doses, whereas only 10 microg/d leptin decreased body fat in Ob/?. Fat pad weights were decreased similarly by leptin in both genotypes. However, apoptosis was increased by leptin in all three fat pads in ob/ob, whereas Ob/? showed significant increases only in retroperitoneal.

DISCUSSION

ob/ob mice had greater overall sensitivity to leptin. Although ob/ob mice appeared to be more sensitive than Ob/? mice to leptin-induced adipose tissue apoptosis, there were differences among adipose depots in responsiveness to leptin-induced apoptosis.

Apoptosis of human carcinoma cells in the presence of inhibitors of glycosphingolipid biosynthesis: I. Treatment of Colo-205 and SKBR3 cells with isomers of PDMP and PPMP

Apoptosis, or programmed cell death, plays an important role in many physiological and diseased conditions. Induction of apoptosis in cancer cells by anti-cancer drugs and biosynthetic inhibitors of cells surface glycolipids in the human colon carcinoma cells (Colo-205) are of interest in recent years. In our present studies, we have employed different stereoisomers of PPMP and PDMP (inhibit GlcT-glycosyltransferase (GlcT-GLT)) to initiate apoptosis in Colo-205 cells grown in culture in the presence of (3)H-TdR and (3)H/or (14)C-L-Serine. Our analysis showed that the above reagents (between 1 to 20 microM) initiated apoptosis with induction of Caspase-3 activities and phenotypic morphological changes in a dose-dependent manner. We have observed an increase of radioactive ceramide formation in the presence of a low concentration (1-4 microM) of these reagents in these cell lines. However, high concentrations (4-20 microM) inhibited incorporation of radioactive serine in the higher glycolipids. Colo-205 cells were treated with L-threo-PPMP (0-20 microM) and activities of different GSL: GLTs were estimated in total Golgi-pellets. The cells contained high activity of GalT-4 (UDP-Gal: LcOse3Cer beta 1-4galactosyltransferase), whereas negligible activity of GalT-3 (UDP-Gal: GM2 beta 1-3galactosyltransferase) or GM2-synthase activity of the ganglioside pathway was detected. Previously, GLTs involved in the biosynthetic pathway of SA-Le(x) formation had been detected in these colon carcinoma (or Colo-205) cells (Basu M et al. Glycobiology 1, 527-35 (1991)). However, during progression of apoptosis in Colo-205 cells with increasing concentrations of L-PPMP, the GalT-4 activity was decreased significantly. These changes in the specific activity of GalT-4 in the total Golgi-membranes could be the resultant of decreased gene expression of the enzyme.

CART peptide: central mediator of leptin-induced adipose tissue apoptosis?

Because of connections between CART peptide containing neurons and the sympathetic nervous system (SNS) and the possible role of the SNS in leptin-induced adipose apoptosis, CART may act as a downstream effector of leptin-induced adipose apoptosis. Male Sprague-Dawley rats received continuous intracerebroventricular (i.c.v.) infusion for 4 days of either artificial cerebrospinal fluid (aCSF, 12 microl/day), leptin (15 microg/day), or CART55-102 at 2.4 microg/day (CART2.4) or 9.6 microg/day (CART9.6). Food intake (FI) was decreased 10.8% for CART2.4, 41.9% for CART9.6 and 33.4% for leptin (p<0.05). CART9.6 and leptin reduced meal size and meal number. Body weight (BW) was reduced by CART9.6 (14.6%) and leptin (11.6%) (p<0.05), but not by CART2.4. CART9.6 and CART2.4, but not leptin, caused hypothermia, and CART9.6 inhibited physical activity (p<0.05). Epididymal, inguinal and retroperitoneal fat pad weights were reduced (p<0.05) by both CART treatments and leptin; CART9.6 also reduced gastrocnemius muscle weight (18.1%, p<0.05). Leptin, but not CART, increased serum free fatty acid concentrations by 31.1% (p<0.05) and increased adipose apoptosis by 48% (p<0.05). These data show that although leptin and CART55-102 have some similar actions, CART55-102 is probably not a mediator for leptin-induced adipose apoptosis in the brain.

Clonidine increases caspase-3 mRNA level and DNA fragmentation in the developing rat brainstem

The densities of alpha2-adrenergic receptors, labeled by 3H-clonidine or 3H-RX821002, reach a peak in the rat brainstem during the first week of its life. This enables the agonist of alpha2-adrenergic receptor clonidine, which is used as a component of anaesthetic solution in infants and children, to have specific effects in this structure of the developing brain. Clonidine was injected into the fetal brain (5 microg in 5 microl of saline) or subcutaneously to the pups (1, 10 microg in 50 microl of saline) 3 days before investigation. Clonidine increased the level of apoptotic enzyme caspase-3 mRNA expression, as measured by RT-PCR and enhanced the DNA fragmentation, as determined by gel electrophoresis, in the brainstem of the 21-day-old fetuses and 8-day-old rats. In the cortex of 8-day-old rat, the alpha2-adrenergic receptors are at a much lower level than the brainstem. Clonidine treatment had no evident effects on caspase-3 mRNA level and DNA fragmentation in the cortex of an 8-day-old rat. The data suggest that clonidine facilitates cell death in the developing brainstem. This drug effect provides a potential mechanism whereby clonidine during early life could induce long-lasting alterations in brain neurochemistry, autonomic functions and behavior.

beta-Adrenergic receptor agonists increase apoptosis of adipose tissue in mice

beta-Adrenergic receptor (beta-AR) agonists increase muscle mass and decrease body fat in rodents and livestock. With oral administration, however, the effects of beta1-AR and beta2-AR can be different, depending on the species tested. We tested the effects of clenbuterol, a beta2-AR agonist, and ractopamine, a beta1/beta2-AR agonist, on growth, adiposity and adipose tissue apoptosis in male and female mice by feeding diets containing control, 200 ppm clenbuterol, or 200 or 800 ppm ractopamine. Food intake (FI) was measured daily; body weight (BW) and temperatures (BT) were measured on days 0, 3, 7, 10, 14, 17, and 20. On day 21 mice were sacrificed, body composition was determined using PIXImus densitometry, and muscle and adipose tissues were collected. There were no treatment effects on BT, FI, BW, feed efficiency or body composition. Retroperitoneal (Rp) and epididymal/parametrial (Epi/Par) fat pad masses were reduced in both 800 ppm ractopamine (40+/-3mg and 207+/-20mg, respectively) and clenbuterol (35+/-7 mg and 211+/-22 mg) treated mice compared to control (66+/-8 mg and 319+/-30 mg, P<0.05). Brown adipose tissue (BAT) mass was greater (P<0.05) in clenbuterol treated mice compared to other treatments. Adipose tissue apoptosis (% DNA fragmentation) was increased in Epi/Par fat pads in clenbuterol (5.2+/-1.1%) and 800 ppm ractopamine (4.1+/-0.8%) treated mice compared to control (1.7+/-0.4%, P<0.05). These findings show that WAT apoptosis can be induced by activation of beta-AR in mice, although the mechanism is unknown.