Dopamine D1 receptor modulation in nucleus accumbens lowers voluntary wheel running in rats bred to run high distances
PHYSIOLOGY & BEHAVIOR
Authors: Roberts, Michael D.; Gilpin, Leigh; Parker, Kyle E.; Childs, Thomas E.; Will, Matthew J.; Booth, Frank W.
Abstract
Dopamine signaling in the nucleus accumbens (NAc) has been postulated to influence reward development towards drugs of abuse and exercise. Herein, we used generation 4-5 rats that were selectively bred to voluntary run high (HVR) versus low (LVR) distances in order to examine if dopamine-like 1 (01) receptor modulation in the NAc differentially affects nightly voluntary wheel running between these lines. A subset of generation 5-6 HVR and LVR rats were also used to study the mRNA expression of key genes related to reward and addiction in the NAc (i.e., DRD1, DRD5. DRD2, Nr4a2, FosB, and BDNF). In a crossover fashion, a D1-like agonist SKF 82958 (2 mu g per side) or D1-like full antagonist SCH 23390 (4 mu g per side) was bilaterally injected into the NAc of HVR and LVR female Wistar rats prior to their high running nights. Notably, during hours 2-4 (between 2000 and 2300) of the dark cycle there was a significant decrement in running distances in the HVR rats treated with the 01 agonist (p=0.025) and antagonist (p=0.017) whereas the running distances in LVR rats were not affected. Interestingly, HVR and LVR rats possessed similar NAc concentrations of the studied mRNAs. These data suggest that: a) animals predisposed to run high distances on a nightly basis may quickly develop a rewarding response to exercise due to an optimal D1-like receptor signaling pathway in the NAc that can be perturbed by either activation or blocking, b) D1-like agonist or antagonist injections do not increase running distances in rats that are bred to run low nightly distances, and c) running differences between HVR and LVR animals are seemingly not due to the expression of the studied mRNAs. Given the societal prevalence of obesity and extraneous physical inactivity, future studies should be performed in order to further determine the culprit for the low running phenotype observed in LVR animals. (C) 2011 Elsevier Inc. All rights reserved.
Analysis of the role of mutations in the KMT2D histone lysine methyltransferase in bladder cancer
FEBS OPEN BIO
Authors: Ding, Beichen; Yan, Libin; Zhang, Yucong; Wang, Zhize; Zhang, Yangjun; Xia, Ding; Ye, Zhangqun; Xu, Hua
Abstract
Histone lysine methyltransferases (HMT) comprise a subclass of epigenetic regulators; dysregulation of these enzymes affects gene expression, which may lead to tumorigenesis. Here, we performed an integrated analysis of 50 HMTs in bladder cancer and found intrinsic links between copy number alterations, mutations, gene expression levels, and clinical outcomes. Through integrative analysis, we identified six HMT genes (PRDM9, ASH1L,SETD3, SETD5, WHSC1L1, and KMT2D) that may play a key role in the development and progression of bladder cancer. Of these six HMTs, histone lysine N-methyltransferase 2D (KMT2D) exhibited the highest mutation rate in bladder cancer. Our comparison of the mRNA and miRNA expression profiles of mutated and wild-type KMT2D suggested that two signaling pathways (FOX1-miR-1224-5p-DLK1 and HIF/GATA5-miR-133a-3p-DRD5) may mediate the tumor suppressive effect of the KMT2D mutation. In summary, our findings indicate that mutations in HMT genes, especially KMT2D mutation, may play a role in the development of bladder cancer.