Construction of a cDNA Library from the Testis and Sequence Analysis of the Ubiquitin Gene from Rana nigromaculata

A full-length cDNA library from the testis of dark-spotted frogs （ Rana nigromaculata ） was constructed with the SMART （switching mechanism at 5＇ end of RNA transcript） technique. Total RNA was extracted from the testis and reverse transcripted into full-length cDNA using PowerScript reverse transcriptase. The first-strand cDNA was amplified using long-distance PCR （LD-PCR）. After Sfi Ⅰ digestion and fractionation, cDNA （ 〉 500 bp） was ligated to λ TriplEx2 vector and packaged with GigapackⅢ Gold Packaging Extract. The titers of optimal primary libraries were 2.0×10^6 pfu/mL and 2.4 × 10^6 pfu/mL and the tlters of the amplified libraries were 0.48 × 10^9 pfu/mL and 3.0 × 10^9 pfu/ mL, respectively. The percentages of recombinant clones of primary libraries and amplified libraries were all over 90%. The libraries were converted into pTriplEx2 plasmids in E. coli BM 25.8 strain. The insert sizes were measured by PCR which showed most fragments were over 500 bp and the average length was 1.0 kb approximately. A positive clone of 1 171 bp was sequenced and named RnUb based on sequence similarity with the known ubiquitin genes in Gen- Bank. This sequence was a full-length cDNA with complete coding sequences, which indicated that the library built a base for screening the full-length cDNA. These data showed that this library attained to the requirements of a standard cDNA library. This library provided a useful resource for the functional genomic research of Rana nigromaculata.

Effect of acupuncture in intervening heroin-induced brain damage via regulating ubiquitin-proteasome pathway

Objective：To observe the effect of acupuncture in regulating ubiquitin-proteasome pathway （UPP）,and discuss the action of acupuncture in intervening heroin-induced brain damage.Methods：Thirty male Sprague-Dawley （SD） rats were divided into a control group,a model group and an acupuncture group by using the random number table.Rats in the model and acupuncture groups received intramuscular heroin injection for successive 8 d at a progressively increased dose.Afterwards,the injection was suspended for 5 d for withdrawal.The heroin relapse rat model was established by repeating the drug addiction and withdrawal process for 3 times.The control group followed the step of the model establishment,but was given intramuscular injection of normal saline at the stage of addiction and no intervention at the stage of withdrawal;the model group was given intramuscular heroin injection at a progressively increased dose at the addiction stage and no intervention at the withdrawal stage;the acupuncture group was dealt in the same way as the model group at the addiction stage,but received acupuncture at Baihui （GV 20） and Dazhui （GV 14） at the withdrawal stage,with the needles retained for 30 min each time,1 session a day,for successive 5 d.On the 39th day,brain tissues were extracted from the hippocampus and ventral tegmental area （VTA） of the three groups of rats.The apoptosis of brain nerve cells was detected by using terminal deoxynucleotidyl transferase-mediated nick and labeling （TUNEL）.The mRNA and protein expressions of ubiquitin （Ub）,ubiquitin protein ligase （E3） and 26S were examined by immunohistochemistry and quantitative real-time polymerase chain reaction （RT-qPCR）.Results：Compared with the model group,rat＇s hippocampus and VTA in the acupuncture group showed significantly fewer cells positively stained by TUNEL staining （P〈0.01）,and its mRNA and protein expressions of Ub,E3,26S were significantly lower （P〈0.01）.Conclusion：Reducing nerve cell apoptosis and regulating the mRNA and protein expressions of Ub,E3 and 26S in rat＇s hippocampus and VTA are possibly one of the action mechanisms of acupuncture in intervening heroin-induced brain damage.

Regulation of inflammasomes by ubiquitination

Inflammasomes are multi-protein complexes that regulate the innate immune response by facilitating the release of inflammatory cytokines in response to pathogen exposure or cellular damage. Pro-inflammatory inflammasome signaling is vital to host defense and helps initiate the process of tissue repair following an insult to the host, but can be injurious, when excessive or chronic. As such, inflammasome activity is tightly regulated. Here we discuss one critical mechanism of inflammasome regulation, ubiquitination, that functions as a universal modulator of protein stability and trafficking. Recent studies have provided important insights into the regulation of inflammasome activation by protein ubiquitination. We review the molecular regulation of inflammasome function, specifically, as it relates to ubiquitination, and discuss the implications for the development of theraoeutics to soecificallv target aberrant inflammasome signaling.

Phosphorylation of Rictor at Thr1135 impairs the Rictor/Cullin-1 complex to ubiquitinate SGK1

The Rictor/mTOR complex plays a pivotal role in a variety of cellular functions including cellular metabolism,cell proliferation and survival by phosphorylating Akt at Ser473 to fully activate the Akt kinase.However,its upstream regulatory pathways as well as whether it has additional function(s)remain largely unknown.We recently reported that Rictor contains a novel ubiquitin E3 ligase activity by forming a novel complex with Cullin-1,but not with other Cullin family members.Furthermore,we identified SGK1 as its downstream target.Interestingly,Rictor,but not Raptor or mTOR,promotes SGK1 ubiquitination.As a result,SGK1 expression is elevated in Rictor^(–/–)MEFs.We further defined that as a feedback mechanism,Rictor can be phosphorylated by multiple AGC family kinases including Akt,S6K and SGK1.Phosphorylation of Rictor at the Thr1135 site did not affect its kinase activity towards phosphorylating its conventional substrates including Akt and SGK1.On the other hand,it disrupted the interaction between Rictor and Cullin-1.Consequently,T1135E Rictor was defective in promoting SGK1 ubiquitination and destruction.This finding further expands our knowledge of Rictor’s function.Furthermore,our work also illustrates that Rictor E3 ligase activity could be governed by specific signaling kinase cascades,and that misregulation of this process might contribute to SGK overexpression which is frequently observed in various types of cancers.

Highlights of the 2nd International Symposium on Tribbles and Diseases: tribbles tremble in therapeutics for immunity, metabolism, fundamental cell biology and cancer

The Tribbles(TRIB) family of pseudokinase proteins has been shown to play key roles in cell cycle, metabolic diseases, chronic inflammatory disease, and cancer development. A better understanding of the mechanisms of TRIB pseudokinases could provide new insights for disease development and help promote TRIB proteins as novel therapeutic targets for drug discovery. At the 2 nd International Symposium on Tribbles and Diseases held on May 7–9, 2018 in Beijing, China, a group of leading Tribbles scientists reported their findings and ongoing studies about the effects of the different TRIB proteins in the areas of immunity, metabolism, fundamental cell biology and cancer. Here, we summarize important and insightful overviews from 4 keynote lectures, 13 plenary lectures and 8 short talks that took place during this meeting. These findings may offer new insights for the understanding of the roles of TRIB pseudokinases in the development of various diseases.