Genetic regulation analysis reveals involvement of tumor necrosis factor and alpha-induced protein 3 in stress response in mice
GENE
Authors: Xu, Jian; Dai, Aihua; Chen, Qi; Liu, Xiaorong; Zhang, Yu; Wang, Hongmei; Li, Haizhen; Chen, Ying; Cao, Maohong
Abstract
In order to study whether Tnfaip3 is related to stress response and further to find it's genetic regulation, we use C57BL/6J (B6) and DBA/2 (D2) mice to built the model of chronic unpredictable mild stress. RT-PCR, Western blotting and immunohistochemistry were used for studying the expression variation of Tnfaip3 in hippocampus tissue of B6 and D2 mice after being stressed. We found that the expression of Tnfaip3 was more remarkably in-creased in chronic unpredictable stress models than that in untreated mice (P < 0.05). It is indicated that Tnfaip3 might take part in the process of stress response. The expression of Tnfaip3 is regulated by a cis-acting quantitative trait locus (cis-eQTL). We identified 5 genes are controlled by Tnfaip3 and the expression of 64 genes highly associated with Tnfaip3, 9 of those have formerly been participate in stress related pathways. In order to estimate the relationship between Tnfaip3 and its downstream genes or network members, we transfected SH-SY5Y cells with Tnfaip3 siRNA leading to down-regulation of Tnfaip3 mRNA. We confirmed a significant influence of Tnfaip3 depletion on the expression of Tsc22d3, Pex7, Rap2a, Slc2a3, and Gap43. These validated downstream genes and members of Tnfaip3 gene network provide us new insight into the biological mechanisms of Tnfaip3 in chronic unpredictable stress. (c) 2015 Elsevier B.V. All rights reserved.
PRENYL GROUP IDENTIFICATION OF RAP2 PROTEINS - A RAS SUPERFAMILY MEMBER OTHER THAN RAS THAT IS FARNESYLATED
BIOCHEMICAL JOURNAL
Authors: FARRELL, FX; YAMAMOTO, K; LAPETINA, EG
Abstract
Rap proteins comprise a subset of the large family of ras-related proteins. They contain the C-terminal tetrapeptide sequence motif Cys-Ali-Ali-Xaa (Ali is an aliphatic amino acid and X is any amino acid), which has been found to be the site of membrane attachment via isoprenylation for ras, nuclear lamins and the gamma subunits of the heterotrimeric G-proteins. To investigate the isoprenylation of rap2a and rap2b, human cDNAs coding for these proteins were expressed in COS cells incubated in the presence of [H-3]mevalonolactone. Both proteins incorporated a product of [H-3]mevalonolactone, as judged by Western blot analysis. To identify the specific isoprenoid attached to each protein, the cDNAs were transcribed in vitro and the rap2 specific RNA was translated in a rabbit reticulocyte lysate system in the presence of [H-3]mevalonolactone. The translation isoprenoid groups were analysed by h.p.l.c. Rap2b, which terminates in Cys-Val-Ile-Leu, is geranylgeranylated as predicted while rap2a, which terminates in Cys-Asn-Ile-Gln, incorporated farnesyl. A mutant construct generated by site-directed mutagenesis of rap2a cDNA yielding a protein terminating in leucine instead of glutamine incorporated geranylgeranyl, lending further support to the notion that isoprenoid specificity is governed by the terminal amino acid. In addition, when the CAAX motif cysteine at position 180 of rap2a was replaced by a serine residue no isoprenoid incorporation was observed. Thus rap2a and rap2b, despite showing 90% sequence identity, incorporate different isoprenoid groups. Thus glutamine is a signal for farnesylation, and rap2a is the first non-ras member of the ras superfamily that is farnesylated.