KIBRA: A New Gateway to Learning and Memory?

The genetic locus encoding KIBRA, a member of the WWC family of proteins, has recently been shown to be associated with human memory performance through genome-wide single nucleotide polymorphism screening. Gene expression analysis and a variety of functional studies have further indicated that such a role is biologically plausible for KIBRA. Here, we review the existing literature, illustrate connections between the different lines of evidence, and derive models based on KIBRA's function(s) in the brain that can be further tested experimentally

Distinctive phosphoinositide- and Ca²⁺-binding properties of normal and cognitive performance–linked variant forms of KIBRA C2 domain

Kidney- and brain-expressed protein (KIBRA), a multifunctional scaffold protein with around 20 known binding partners, is involved in memory and cognition, organ size control via the Hippo pathway, cell polarity, and membrane trafficking. KIBRA includes tandem N-terminal WW domains, a C2 domain, and motifs for binding atypical PKC and PDZ domains. A naturally occurring human KIBRA variant involving residue changes at positions 734 (Met-to-Ile) and 735 (Ser-to-Ala) within the C2 domain affects cognitive performance. We have elucidated 3D structures and calcium- and phosphoinositide-binding properties of human KIBRA C2 domain. Both WT and variant C2 adopt a canonical type I topology C2 domain fold. Neither Ca²⁺ nor any other metal ion was bound to WT or variant KIBRA C2 in crystal structures, and Ca²⁺ titration produced no significant reproducible changes in NMR spectra. NMR and X-ray diffraction data indicate that KIBRA C2 binds phosphoinositides via an atypical site involving β-strands 5, 2, 1, and 8. Molecular dynamics simulations indicate that KIBRA C2 interacts with membranes via primary and secondary sites on the same domain face as the experimentally identified phosphoinositide-binding site. Our results indicate that KIBRA C2 domain association with membranes is calcium-independent and involves distinctive C2 domain–membrane relative orientations.

An aPKC-Exocyst Complex Controls Paxillin Phosphorylation and Migration through Localised JNK1 Activation

The exocyst/aPKC complex controls the spatiotemporal activation of the kinases JNK and ERK at the leading edge of migrating cells and thereby controls the dynamic behaviour of the adhesion protein paxillin during cell migration

The RNA Polymerase Dictates ORF1 Requirement and Timing of LINE and SINE Retrotransposition

Mobile elements comprise close to one half of the mass of the human genome. Only LINE-1 (L1), an autonomous non-Long Terminal Repeat (LTR) retrotransposon, and its non-autonomous partners—such as the retropseudogenes, SVA, and the SINE, Alu—are currently active human retroelements. Experimental evidence shows that Alu retrotransposition depends on L1 ORF2 protein, which has led to the presumption that LINEs and SINEs share the same basic insertional mechanism. Our data demonstrate clear differences in the time required to generate insertions between marked Alu and L1 elements. In our tissue culture system, the process of L1 insertion requires close to 48 hours. In contrast to the RNA pol II-driven L1, we find that pol III transcribed elements (Alu, the rodent SINE B2, and the 7SL, U6 and hY sequences) can generate inserts within 24 hours or less. Our analyses demonstrate that the observed retrotransposition timing does not dictate insertion rate and is independent of the type of reporter cassette utilized. The additional time requirement by L1 cannot be directly attributed to differences in transcription, transcript length, splicing processes, ORF2 protein production, or the ability of functional ORF2p to reach the nucleus. However, the insertion rate of a marked Alu transcript drastically drops when driven by an RNA pol II promoter (CMV) and the retrotransposition timing parallels that of L1. Furthermore, the “pol II Alu transcript” behaves like the processed pseudogenes in our retrotransposition assay, requiring supplementation with L1 ORF1p in addition to ORF2p. We postulate that the observed differences in retrotransposition kinetics of these elements are dictated by the type of RNA polymerase generating the transcript. We present a model that highlights the critical differences of LINE and SINE transcripts that likely define their retrotransposition timing

LGR5 Is a Negative Regulator of Tumourigenicity, Antagonizes Wnt Signalling and Regulates Cell Adhesion in Colorectal Cancer Cell Lines

BACKGROUND: LGR5 (Leucine-rich repeat-containing G-protein coupled receptor 5) is the most established marker for intestinal stem cells. Mouse models show that LGR5+ cells are the cells of origin of intestinal cancer, and LGR5 expression is elevated in human colorectal cancers, however very little is known about LGR5 function or its contribution to the stem cell phenotype and to colorectal cancer. PRINCIPAL FINDINGS: We have modulated the expression of LGR5 by RNAi (inhibitory RNAs) or overexpression in colorectal cancer cell lines. Paradoxically, ablation of LGR5 induces increased invasion and anchorage-independent growth, and enhances tumourigenicity in xenografts experiments. Conversely, overexpression of LGR5 augments cell adhesion, reduces clonogenicity and attenuates tumourigenicity. Expression profiling revealed enhanced wnt signalling and upregulation of EMT genes upon knockdown of LGR5, with opposite changes in LGR5 overexpressing cells. These findings suggest that LGR5 is important in restricting stem cells to their niche, and that loss of LGR5 concomitant with activated wnt signalling may contribute to the invasive phenotype of colorectal carcinomas

Effects of Anacetrapib in Patients with Atherosclerotic Vascular Disease

BACKGROUND: Patients with atherosclerotic vascular disease remain at high risk for cardiovascular events despite effective statin-based treatment of low-density lipoprotein (LDL) cholesterol levels. The inhibition of cholesteryl ester transfer protein (CETP) by anacetrapib reduces LDL cholesterol levels and increases high-density lipoprotein (HDL) cholesterol levels. However, trials of other CETP inhibitors have shown neutral or adverse effects on cardiovascular outcomes. METHODS: We conducted a randomized, double-blind, placebo-controlled trial involving 30,449 adults with atherosclerotic vascular disease who were receiving intensive atorvastatin therapy and who had a mean LDL cholesterol level of 61 mg per deciliter (1.58 mmol per liter), a mean non-HDL cholesterol level of 92 mg per deciliter (2.38 mmol per liter), and a mean HDL cholesterol level of 40 mg per deciliter (1.03 mmol per liter). The patients were assigned to receive either 100 mg of anacetrapib once daily (15,225 patients) or matching placebo (15,224 patients). The primary outcome was the first major coronary event, a composite of coronary death, myocardial infarction, or coronary revascularization. RESULTS: During the median follow-up period of 4.1 years, the primary outcome occurred in significantly fewer patients in the anacetrapib group than in the placebo group (1640 of 15,225 patients [10.8%] vs. 1803 of 15,224 patients [11.8%]; rate ratio, 0.91; 95% confidence interval, 0.85 to 0.97; P=0.004). The relative difference in risk was similar across multiple prespecified subgroups. At the trial midpoint, the mean level of HDL cholesterol was higher by 43 mg per deciliter (1.12 mmol per liter) in the anacetrapib group than in the placebo group (a relative difference of 104%), and the mean level of non-HDL cholesterol was lower by 17 mg per deciliter (0.44 mmol per liter), a relative difference of -18%. There were no significant between-group differences in the risk of death, cancer, or other serious adverse events. CONCLUSIONS: Among patients with atherosclerotic vascular disease who were receiving intensive statin therapy, the use of anacetrapib resulted in a lower incidence of major coronary events than the use of placebo. (Funded by Merck and others; Current Controlled Trials number, ISRCTN48678192 ; ClinicalTrials.gov number, NCT01252953 ; and EudraCT number, 2010-023467-18 .)

FRMPD1 activates the Hippo pathway via interaction with WWC3 to suppress the proliferation and invasiveness of lung cancer cells

Xuezhu Rong,1 Qiang Han,1 Xuyong Lin,1 Joachim Kremerskothen,2 Enhua Wang11Department of Pathology, College of Basic Medical Sciences and First Affiliated Hospital, China Medical University, Shenyang, People’s Republic of China; 2Internal Medicine D, Department of Nephrology, Hypertension and Rheumatology, University Hospital Muenster, Muenster, GermanyPurpose: The expression of FERM-domain-containing protein-1 (FRMPD1)/FERM and PDZ domain-containing protein-2 (FRMD2) in malignant tumors, including lung cancer, and its underlying molecular mechanism have not been reported yet.Materials and methods: Immunohistochemistry was performed to analyze the expression of FRMPD1 in lung cancer tissues, and statistical analysis was applied to analyze the relationship between FRMPD1 expression and clinicopathological factors. The biological effects of FRMPD1 on lung cancer cell proliferation and invasion were determined by functional experiments both in vivo and in vitro. Immunoblotting, RT-qPCR, dual-luciferase assay, and immunofluorescence were performed to demonstrate whether FRMPD1 stimulates Hippo signaling. Co-immunoprecipitation assays were used to clarify the underlying role of FRMPD1 in Hippo pathway activation via interaction with WW and C2 domain containing protein-3 (WWC3).Results: We found that FRMPD1 expression in lung cancer specimens was lower than that in normal bronchial epithelium and normal submucosal glands. FRMPD1 expression had a negative correlation with age, Tumor-Node-Metastasis (TNM) stage, lymph node metastasis, as well as poor prognosis. Moreover, ectopic expression of FRMPD1 significantly inhibited the proliferation and invasion of lung cancer cells, and inhibition of FRMPD1 expression led to opposite effects. Mechanistically, we found that FRMPD1 interacted with the C-terminal PDZ binding motif of WWC3 via its PSD95/DLG/ZO1 (PDZ) domain and promoted the phosphorylation of large tumor suppressor-1 (LATS1), thus inhibiting the nuclear translocation of yes-associated protein (YAP).Conclusion: FRMPD1 could activate the Hippo pathway and ultimately inhibit the malignant behavior of lung cancer cells through its interaction with WWC3. This work will provide an important experimental basis for the discovery of novel biomarkers of lung cancer and the development of targeted drugs.Keywords: FRMPD1, Hippo pathway, LATS1, NSCLC, WWC

The BC200 RNA gene and its neural expression are conserved in Anthropoidea (Primates)

The gene encoding BC200 RNA arose from a monomeric Alu element. Subsequently, the RNA had been recruited or exapted into a function of the nervous system. Here we confirm the presence of the BC200 gene in several primate species among the Anthropoidea. The period following the divergence of New World monkeys and Old World monkeys from their common ancestor is characterized by a significantly higher substitution rate in the examined 5' flanking region than in the BC200 RNA coding region itself. Furthermore, the conservation of CpG dimers in the RNA coding region (200 bp) is drastically increased compared to the 5' flanking region (~400 bp) over all 12 species examined. Finally, the brain-specific expression pattern of BC200 RNA and its presence as a ribonucleoprotein particle (RNP) are conserved in Old World and New World monkeys. Our studies indicate that the gene encoding BC200 RNA was created at least 35-55 million years ago and its presence, mode of expression, and association with protein(s) as an RNP are under selective pressure

WWC3 inhibits epithelial–mesenchymal transition of lung cancer by activating Hippo-YAP signaling

Qiang Han,1 Joachim Kremerskothen,2 Xuyong Lin,1 Xiupeng Zhang,1 Xuezhu Rong,1 Di Zhang,1 Enhua Wang1 1Department of Pathology, College of Basic Medical Sciences, First Affiliated Hospital of China Medical University, Shenyang, People’s Republic of China; 2Internal Medicine D, Department of Nephrology, Hypertension and Rheumatology, University Hospital Muenster, Muenster, Germany Background: Though we recently reported that the WWC3 inhibits the invasiveness and metastasis of lung cancer by activating the Hippo pathway, the impact and underlying mechanisms of this process still remain unclear. Methods: To identify the role of WWC3 in epithelial-mesenchymal transition of lung cancer, we performed immunohistochemistry to detect the expression levels of WWC3 and EMT-related biomarker, and analyzed their correlations in a cohort of 127 patients with NSCLC. Wound healing assay and cell invasion assay were applied to explore cell invasive ability change after WWC3 knockdown. qRT-PCR and immunoblotting were performed to assess mRNA and protein levels of EMT-related biomarkers and the main molecules changes of Hippo signaling caused by WWC3. Immunoprecipition was to examine WWC3 and LATS1 interaction. Results: WWC3 knockdown drives a pronounced shift from the epithelial to the mesenchymal phenotype in lung cancer cells. In addition, WWC3 ectopic expression in lung cancer cells attenuates mesenchymal markers and increases the epithelial markers expressions; however, WWC3-ΔWW plasmid abrogated these effects. WWC3 silencing by shRNA exerts the opposite effect. Furthermore, WWC3 levels were inversely correlated with the levels of EMT inducers (Snail and Slug) in lung cancer cells and specimens. Immunoblotting revealed that WWC3 wild-type upregulates large tumor suppressor (LATS1) and yes-associated protein (YAP) phosphorylation through its WW domain, hence activating Hippo pathway. Knockdown of YAP and LATS1, as well as the as the Verteporfin (VP) usage, could reverse this effect caused by WWC3 silencing. Conclusion: These findings suggest that WWC3 works as a tumor suppressor to inhibit EMT process and confer its candidacy as a potential therapeutic target in lung cancer. Keywords: WWC3, epithelial–mesenchymal transition, Hippo pathway, YAP, nonsmall-cell lung cance