Cdc2-like kinase 2 in the hypothalamus is necessary to maintain energy homeostasis.

OBJECTIVE: To investigate whether the Cdc2-like kinase 2 (CLK2) is expressed in hypothalamic neurons and if it is, whether the hypothalamic CLK2 has a role in the regulation of energy balance. SUBJECTS: Swiss mice on chow or high-fat diet (HFD) and db/db mice on chow diet were used to address the role of CLK2 in the hypothalamus. RESULTS: Hypothalamic CLK2Thr343 phosphorylation, which induces CLK2 activity, is regulated in vivo by refeeding, insulin and leptin, in a PI3K (phosphoinositide 3-kinase)-dependent manner. The reduction of CLK2 expression in the hypothalamus, by chronic pharmacological inhibition with TG003 or by chronic knockdown with small interfering RNA was sufficient to abolish the anorexigenic effect of insulin and leptin, to increase body weight, fat mass, food intake and to decrease energy expenditure in mice on chow. In contrast, CLK2Thr343 phosphorylation in the hypothalamus in response to insulin, leptin or refeeding was impaired in mice on HFD or in db/db mice. Chronic CLK2 inhibition in the hypothalamus was associated with a slight increase in the fasting blood glucose levels, reduction in PEPCK (phosphoenolpyruvate carboxykinase) expression in the liver and enhanced glucose production from pyruvate, suggesting a regulation of hepatic glucose production. Further, overexpressing CLK2 in the mediobasal hypothalami of mice on HFD or in db/db mice by adenovirus partially reversed the obese phenotype. CONCLUSIONS: Thus, our results suggest that protein CLK2 integrates some important hypothalamic pathways, and may be a promising molecule for new therapeutic approaches for obesity and diabetes.

Pioglitazone treatment increases food intake and decreases energy expenditure partially via hypothalamic adiponectin/adipoR1/AMPK pathway.

INTRODUCTION: Thiazolidinediones (TZDs) enhanced body weight (BW) partially by increased adipogenesis and hyperphagia. Neuronal PPARγ knockout mice on high-fat diet (HFD) are leaner because of enhanced leptin response, although it could be secondary to their leanness. Thus, it still is an open question how TZDs may alter energy balance. Multiple factors regulate food intake (FI) and energy expenditure (EE), including anorexigenic hormones as insulin and leptin. Nonetheless, elevated hypothalamic AMPK activity increases FI and TZDs increase AMPK activity in muscle cells. Thus, the aim of the present study was to investigate whether Pioglitazone (PIO) treatment alters hypothalamic insulin and leptin action/signaling, AMPK phosphorylation, and whether these alterations may be implicated in the regulation of FI and EE. METHODS: Swiss mice on HFD (2 months) received PIO (25 mg kg(-1) per day-gavage) or vehicle for 14 days. AMPK and AdipoR1 were inhibited via Intracerebroventricular injections using Compound C (CompC) and small interference RNA (siRNA), respectively. Western blot, real-time PCR and CLAMS were done. RESULTS: PIO treatment increased BW, adiposity, FI, NPY mRNA and decreased POMC mRNA expression and EE in HFD mice. Despite higher adiposity, PIO treatment improved insulin sensitivity, glucose tolerance, decreased insulin and increased adiponectin serum levels. This result was associated with, improved insulin and leptin action/signaling, decreased α2AMPK(Ser491) phosphorylation and elevated Acetyl-CoA carboxylase and AMPK(Thr172) phosphorylation in hypothalamus. The inhibition of hypothalamic AMPK with CompC was associated with decreased adiposity, FI, NPY mRNA and EE in PIO-treated mice. The reduced expression of hypothalamic AdipoR1 with siRNA concomitantly with PIO treatment reverted PIO induced obesity development, suggesting that adiponectin may be involved in this effect. CONCLUSIONS: These results demonstrated that PIO, despite improving insulin/leptin action in hypothalamus, increases FI and decreases EE, partially, by activating hypothalamic adiponectin/AdipoR1/AMPK axis. Suggesting a novel mechanism in the hypothalamus by which TZDs increase BW.

Malignant mesothelioma following treatment for Hodgkin's disease.

PURPOSE: Asbestos exposure is the major known risk factor for mesothelioma, but several case reports have suggested a link between radiation therapy and subsequent development of malignant mesothelioma. This report explores a possible association between radiation therapy for Hodgkin's disease and mesothelioma. PATIENTS AND METHODS: Four cases of malignant mesothelioma were observed following Hodgkin's disease at the Mesothelioma Clinic of the Dana-Farber Cancer Institute. A fifth such patient was found after a review of the literature. RESULTS: In all five cases, the mesothelioma arose in the field of prior radiotherapy. No history of asbestos exposure was elicited by careful questioning or by review of chest radiographs. Examination of lung tissue in one patient showed 250 ferruginous bodies per gram of lung tissue, consistent with no significant prior exposure. The mean interval between radiation treatment for Hodgkin's disease and development of mesothelioma was 15 years, which emphasizes the need for continued follow-up and evaluation of these patients and supports a causal relationship. CONCLUSION: Mesothelioma may need to be added to the list of second malignancies that arise following radiation therapy for Hodgkin's disease. Further support is given to a causal link between radiation exposure and mesothelioma.

Incidence, presentation and promising new treatments for malignant mesothelioma.

It is predicted that up to 80,000 cases of mesothelioma will occur in the next 20 years, and thus it is increasingly important to better understand this disease. There is much controversy over the best treatment, which ranges from supportive care alone to aggressive debulking surgery combined with radiation and chemotherapy. This article summarizes the results with these various regimens to date, and discusses promising new options for therapy that may ultimately lead to increased survival.

Role of the intrinsic transglutaminase in the Ca2+-mediated crosslinking of erythrocyte proteins.

Transamidase (i.e., "transglutaminase") activity of human erythrocytes, lysed by a single freezing and thawing to 37 degrees, was measured by a method of incorporating [14C]putrescine into N,N'-dimethylcasein. In the absence of added calcium ions, virtually no enzyme activity could be detected. An increase in concentration of the cation to about 0.5 mM, however, turned on the enzyme to appreciable levels of activity. Simultaneously, Ca2+ produced formation of high molecular weight, nondisulfied bonded protein polymers either directly in the lysate or in fresh cells when the cation was added together with the A23187 ionophore. The polymers could be readily identified in the isolated cell ghosts by means of disc gel electrophoresis. If the Ca2+-promoted formation of polymers was allowed to take place in the presence of 14C-putrescine, then this tracer became incorporated into the polymeric material. The incorporation indicated that polymerization occurred through gamma-glutamyl-epsilon-lysine bridtes. It is suggested that the intrinsic transamidase mediates protein crosslinking of the erythrocyte membrane whenever there is an increase in intracellular Ca2+ concentration. The presence of suitable transglutaminase substrates, e.g. histamine, inhibited crosslinking when the cells were incubated with Ca2+ and ionophore.