Shank2 associates with and regulates Na+/H+ exchanger 3

Na+/H+ exchanger 3 (NHE3) plays a pivotal role in transepithelial Na+ and HCO3(-) absorption across a wide range of epithelia in the digestive and renal-genitourinary systems. Accumulating evidence suggests that PDZ-based adaptor proteins play an important role in regulating the trafficking and activity of NHE3. A search for NHE3-binding modular proteins using yeast two-hybrid assays led us to the PDZ-based adaptor Shank2. The interaction between Shank2 and NHE3 was further confirmed by immunoprecipitation and surface plasmon resonance studies. When expressed in PS120/NHE3 cells, Shank2 increased the membrane expression and basal activity of NHE3 and attenuated the cAMP-dependent inhibition of NHE3 activity. Furthermore, knock-down of native Shank2 expression in Caco-2 epithelial cells by RNA interference decreased NHE3 protein expression as well as activity but amplified the inhibitory effect of cAMP on NHE3. These results indicate that Shank2 is a novel NHE3 interacting protein that is involved in the fine regulation of transepithelial salt and water transport through affecting NHE3 expression and activity.     

A survey of overweight,body shape perception and eating attitude of Korean female university students

[Purpose]

We obtained basic data on a proper weight loss training program by considering the relationship between body mass index (BMI), the perception of appearance, and eating attitudes of Korean female university students.

[Methods]

The survey and anthropometry for the perception of appearance and eating attitudes were conducted targeting 657 female university students located in Seoul, Busan, Ulsan, Daejeon, Chungcheongnam-do, and Gangwon-do South Korea who were not specializing in physical education.

[Results]

The underweight group accounted for 21.16% of the population, the normal weight group comprised 69.71%, the overweight group was 6.09%, and the obese group accounted for 3.04%. The satisfaction rate of appearance was 56.16%, the dissatisfaction rate was 43.84%, and normal-weight students who were dissatisfied with their own appearance comprised 48.5%. The More obese students were more dissatisfied with their appearance. As a result of investigating eating attitudes, 37.75% of all subjects had a risk for an eating disorder, and 38.6% were normal weight but showed a risk for an eating disorder. More obese (BMI) subjects were at higher risk for an eating disorder.

[Conclusion]

The BMIs of the Korean female university students were lower than those of European and American Caucasian women students, but the dissatisfaction of Korean female university students with their appearances was greater than that of European and American students, indicating that more Korean female university students were suffering from an eating disorder. It is predicted that the incidence of eating disorders, such as anorexia and bulimia, will rise in Korean women if there is no accurate understanding and measure to identify the high risk group for an eating disorder.     

Genetic enhancement of behavioral itch responses in mice lacking phosphoinositide 3-kinase-γ (PI3Kγ)

Protein interacting with C Kinase 1 (PICK1), a PDZ domain-containing scaffolding protein, interacts with multiple different proteins in the mammalian nervous system and is believed to play important roles in diverse physiological and pathological conditions. In this study, we report that PICK1 is expressed in neurons of the dorsal root ganglion (DRG) and spinal cord dorsal horn, two major pain-related regions. PICK1 was present in approximately 29.7% of DRG neurons, most of which were small-less than 750 μm² in cross-sectional area. Some of these PICK1-positive cells co-labeled with isolectin B4 or calcitonin-gene-related peptide. In the dorsal horn, PICK1 immunoreactivity was concentrated in the superficial dorsal horn, where it was prominent in the postsynaptic density, axons, and dendrites. Targeted disruption of PICK1 gene did not affect basal paw withdrawal responses to acute noxious thermal and mechanical stimuli or locomotor reflex activity, but it completely blocked the induction of peripheral nerve injury-induced mechanical and thermal pain hypersensitivities. PICK1 appears to be required for peripheral nerve injury-induced neuropathic pain development and to be a potential biochemical target for treating this disorder.     

Serum amyloid A1 is involved in amyloid plaque aggregation and memory decline in amyloid beta abundant condition

Transgenic Research - Alzheimer's disease (AD) is a neurodegenerative disorder, characterized by cognitive impairment, progressive neurodegeneration, and amyloid-β (Aβ) lesion. In the...     

Activity of TSC2 is inhibited by AKT-mediated phosphorylation and membrane partitioning

Loss of tuberin, the product of TSC2 gene, increases mammalian target of rapamycin (mTOR) signaling, promoting cell growth and tumor development. However, in cells expressing tuberin, it is not known how repression of mTOR signaling is relieved to activate this pathway in response to growth factors and how hamartin participates in this process. We show that hamartin colocalizes with hypophosphorylated tuberin at the membrane, where tuberin exerts its GTPase-activating protein (GAP) activity to repress Rheb signaling. In response to growth signals, tuberin is phosphorylated by AKT and translocates to the cytosol, relieving Rheb repression. Phosphorylation of tuberin at serines 939 and 981 does not alter its intrinsic GAP activity toward Rheb but partitions tuberin to the cytosol, where it is bound by 14-3-3 proteins. Thus, tuberin bound by 14-3-3 in response to AKT phosphorylation is sequestered away from its membrane-bound activation partner (hamartin) and its target GTPase (Rheb) to relieve the growth inhibitory effects of this tumor suppressor.     

Effect of cadmium exposure on the globin protein expression in 4th instar larvae of Chironomus riparius Mg. (Diptera: Chironomidae): An ecotoxicoproteomics approach

In order to identify Chironomus hemoglobin (Hb) as a biomarker of ecotoxicity monitoring; herein, the effects of cadmium chloride (Cd) on Hb parameters were investigated in the 4th instar larvae of Chironomus riparius. The expressions of globin mRNA and hemolymph protein, using ecotoxicoproteomic approach, were investigated. Conventional ecotoxicity tests were also conducted to validate the ecotoxicological relevance of the response of Chironomus Hb as a biomarker. The proteomic analysis indicated that exposure to Cd lead alteration in the expression of hemolymph protein, with the total expressions of 12 hemolymph protein spots decreasing in response to treatment, with that of two increasing in response to Cd exposure. In addition, all of the spots differentially expressed in response to Cd treatment were identified as globin proteins. The decreased total Hb content observed in the hemolymph of larvae exposed to Cd suggested that the decreased expression of selected globin proteins in response to Cd exposure impacted on Hb synthesis. The overall results suggested that Hb could be a target molecule for exposure to Cd in C. riparius, with a proteomic approach appearing to be an ideal tool for the discovery of biomarkers in ecotoxicological research.     

MutY is down-regulated by oxidative stress in E. coli

In Escherichia coli, MutM (8-oxoG DNA glycosylase/lyase or Fpg protein), MutY (adenine DNA glycosylase) and MutT (8-oxodGTPase) function cooperatively to prevent mutation due to 7, 8-dihydro-8-oxoguanine (8-oxoG), a highly mutagenic oxidative DNA adduct. MutM activity has been demonstrated to be induced by oxidative stress. Its regulation is under the negative control of the global regulatory genes, fur, fnr and arcA. However, interestingly the presence of MutY increases the mutation frequency in mutT- background because of MutY removes adenine (A) from 8-oxoG:A which arises from the misincorporation of 8-oxoG against A during DNA replication. Accordingly we hypothesized that the response of MutY to oxidative stress is opposite to that of MutM and compared the regulation of MutY activity with MutM under various oxidative stimuli. Unlike MutM, MutY activity was reduced by oxidative stress. Its activity was reduced to 30% of that of the control when E. coli was treated with paraquat (0.5 mM) or H

2

O

2

(0.1 mM) and induced under anaerobic conditions to more than twice that observed under aerobic conditions. The reduced mRNA level of MutY coincided with its reduced activity by paraquat treatment. Also, the increased activity of MutY in anaerobic conditions was reduced further in E. coli strains with mutations in fur, fnr and arcA and the maximum reduction in activity was when all mutations were present in combination, indicating that MutY is under the positive control of these regulatory genes. Therefore, the down-regulation of MutY suggests that there has been complementary mechanism for its mutagenic activity under special conditions. Moreover, the efficacy of anti-mutagenic action should be enhanced by the reciprocal co-regulation of MutM.     

In vitro evidence for the recognition of 8-oxoGTP by Ras, a small GTP-binding protein

Oxygen radicals attack guanine bases in DNA but they also attack cytoplasmic GTP forming 8-oxoGTP. The presence of 8-oxoGTP in cytoplasm is evidenced by the fact that cells contain MutT/MTH1 which hydrolyze 8-oxoGTP into 8-oxoGMP. In this study, the interaction between 8-oxoGTP and Ras, a small GTP-binding protein, was tested in vitro, and the action of 8-oxoGTP was compared to that of GTP. When purified Ras was treated with 8-oxoGTPgammaS, Ras was activated, as indicated by the enhanced binding of Ras with Raf-1. GTPgammaS also activated Ras but 8-oxoGTPgammaS had a much more potent effect. In lysates of human embryo kidney 293 cells, 8-oxoGTPgammaS activated not only Ras but also the downstream effectors of the Ras-ERK pathway, i.e., Raf-1 and ERK1/2. In contrast to Ras, other small GTP-binding proteins, Rac1 and Cdc42, were inactivated by 8-oxoGTPgammaS, whereas both of these proteins were activated by GTPgammaS, indicating that the biological natures of 8-oxoGTP and GTP differ. These results suggest the possibility that 8-oxoGTP is not a simple by-product but a functional molecule transmitting an oxidative signal to small GTP-binding proteins like Ras.     

Pro-IL-16 regulation in activated murine CD4+ lymphocytes

Prior DNA microarray studies suggested that IL-16 mRNA levels decrease following T cell activation, a property unique among cytokines. We examined pro-IL-16 mRNA and protein expression in resting and anti-CD3 mAb-activated primary murine CD4(+) T cells. Consistent with the microarray reports, pro-IL-16 mRNA levels fell within 4 h of activation, and this response is inhibited by cyclosporin A. Total cellular pro-IL-16 protein also fell, reaching a nadir at 48 h. Pro-IL-16 comprises a C-terminal cytokine domain and an N-terminal prodomain that are cleaved by caspase-3. Pro-IL-16 expressed in transfected tumor cells was previously shown to translocate to the nucleus and to promote G(0)/G(1) arrest by stabilizing the cyclin-dependent kinase inhibitor p27(Kip1). In the present study, we observed increased S-phase kinase-associated protein 2 mRNA expression in IL-16 null mice, but basal expression and activation-dependent regulation of p27(Kip1) were no different from wild-type mice. Stimulation with anti-CD3 mAb induced transiently greater thymidine incorporation in IL-16-deficient CD4(+) T cells than wild-type controls, but there was no difference in cell survival or in the CFSE dilution profiles. Analysis of CD4(+) T cell proliferation in vivo using BrdU labeling similarly failed to identify a hyperproliferative phenotype in T cells lacking IL-16. These data demonstrate that pro-IL-16 mRNA and protein expression are dynamically regulated during CD4(+) T cell activation by a calcineurin-dependent mechanism, and that pro-IL-16 might influence T cell cycle regulation, although not in a dominant manner.