The Clinical and Biological Effects of Receptor Expression-Enhancing Protein 6 in Tongue Squamous Cell Carcinoma.

There are currently no effective biomarkers for the diagnosis and treatment of tongue squamous cell carcinoma (TSCC), which causes a poor 5-year overall survival rate. Thus, it is crucial to identify more effective diagnostic/prognostic biomarkers and therapeutic targets for TSCC patients. The receptor expression-enhancing protein 6 (REEP6), a transmembrane endoplasmic reticulum resident protein, controls the expression or transport of a subset of proteins or receptors. Although it was reported that REEP6 plays a role in lung and colon cancers, its clinical impact and biological role in TSCC are still unknown. The present study aimed to identify a novel effective biomarker and therapeutic target for TSCC patients. Expression levels of REEP6 in specimens from TSCC patients were determined with immunohistochemistry. Gene knockdown was used to evaluate the effects of REEP6 in cancer malignancy (colony/tumorsphere formation, cell cycle regulation, migration, drug resistance and cancer stemness) of TSCC cells. The clinical impact of REEP6 expression and gene co-expression on prognosis were analyzed in oral cancer patients including TSCC patients from The Cancer Genome Atlas database. Tumor tissues had higher levels of REEP6 compared to normal tissues in TSCC patients. Higher REEP6 expression was related to shorter disease-free survival (DFS) in oral cancer patients with poorly differentiated tumor cells. REEP6-knocked-down TSCC cells showed diminished colony/tumorsphere formation, and they also caused G1 arrest and decreased migration, drug resistance and cancer stemness. A high co-expression of REEP6/epithelial-mesenchymal transition or cancer stemness markers also resulted in poor DFS in oral cancer patients. Thus, REEP6 is involved in the malignancy of TSCC and might serve as a potential diagnostic/prognostic biomarker and therapeutic target for TSCC patients.

Cardiac fibrosis in mouse expressing DsRed tetramers involves chronic autophagy and proteasome degradation insufficiency.

Proteinopathy in the heart which often manifests excessive misfolded/aggregated proteins in cardiac myocytes can result in severe fibrosis and heart failure. Here we developed a mouse model, which transgenically express tetrameric DsRed, a red fluorescent protein (RFP), in an attempt to mimic the pathological mechanisms ofcardiac fibrosis. Whilst DsRed is expressed and forms aggregation in most mouse organs, certain pathological defects are specifically recapitulated in cardiac muscle cells including mitochondria damages, aggresome-like residual bodies, excessive ubiquitinated proteins, and the induction of autophagy. The proteinopathy and cellular injuries caused by DsRed aggregates may be due to impaired or overburdened ubiquitin-proteasome system and autophagy-lysosome systems. We further identified that DsRed can be ubiquitinated and associated with MuRF1, a muscle-specific E3 ligase. Concomitantly, an activation of NF-κB signaling and a strong TIMP1 induction were noted, suggesting that RFP-induced fibrosis was augmented by a skewed balance between TIMP1 and MMPs. Taken together, our study highlights the molecular consequences of uncontrolled protein aggregation leading to congestive heart failure, and provides novel insights into fibrosis formation that can be exploited for improved therapy.

Neonatal Death and Heart Failure in Mouse with Transgenic HSP60 Expression.

Mitochondrial heat shock proteins, such as HSP60, are chaperones responsible for the folding, transport, and quality control of mitochondrial matrix proteins and are essential for maintaining life. Both prosurvival and proapoptotic roles have been proposed for HSP60, and HSP60 is reportedly involved in the initiation of autoimmune, metabolic, and cardiovascular diseases. The role of HSP60 in pathogenesis of these diseases remains unclear, partly because of the lack of mouse models expressing HSP60. In this study we generated HSP60 conditional transgenic mice suitable for investigating in vivo outcomes by expressing HSP60 at the targeted organ in disease models. Ubiquitous HSP60 induction in the embryonic stage caused neonatal death in mice at postnatal day 1. A high incidence of atrial septal defects was observed in HSP60-expressing mice, with increased apoptosis and myocyte degeneration that possibly contributed to massive hemorrhage and sponge-like cardiac muscles. Our results showed that neonatal heart failure through HSP60 induction likely involves developmental defects and excessive apoptosis. The conditional HSP60 mouse model is useful for studying crucial biological questions concerning HSP60.

Suppression subtractive hybridization-mediated transcriptome analysis from multiple tissues of aspen (Populus tremuloides) altered in phenylpropanoid metabolism.

A PCR-based suppression subtractive hybridization (SSH) technique was used to identify differentially expressed genes in developing tissues of control and transgenic aspen (Populus tremuloides Michx.) with down-regulated 4CL1 (4-coumarate:coenzyme A ligase) expression and enhanced growth. A total of 11,308 expressed sequence tags (ESTs) representing 5,028 non-redundant transcripts encoding 4,224 unique proteins was obtained from shoot apex, young stem, young leaf and root tip SSH libraries. Putative functions can be assigned to 60% of these transcripts. Approximately 14% of the ESTs are not represented among the 111,000 entries already present in Populus EST databases. In general, ESTs of the metabolism class occurred at a higher frequency in control- than transgenic-enriched libraries of all tissues, whereas protein synthesis and protein fate ESTs were over-represented in meristematic tissues of transgenics where 4CL1 was relatively strongly suppressed. Among all tissues, leaves yielded the highest percentage of ESTs with either unknown protein function or insignificant similarity to other protein/DNA/EST sequences in existing databases. Of particular interest was a large number of ESTs (16%) associated with signal transduction in transgenic leaves. Among these were several leucine-rich-repeat receptor-like protein kinases with markedly elevated expression in transgenic leaves. We also identified homologs of transposable elements that were up-regulated in transgenic tissues, providing the first experimental data for active expression of DNA mobile elements in long-lived tree species.

Differential expression of two distinct phenylalanine ammonia-lyase genes in condensed tannin-accumulating and lignifying cells of quaking aspen.

Lignins, along with condensed tannins (CTs) and salicylate-derived phenolic glycosides, constitute potentially large phenylpropanoid carbon sinks in tissues of quaking aspen (Populus tremuloides Michx.). Metabolic commitment to each of these sinks varies during development and adaptation, and depends on L-phenylalanine ammonia-lyase (PAL), an enzyme catalyzing the deamination of L-phenylalanine to initiate phenylpropanoid metabolism. In Populus spp., PAL is encoded by multiple genes whose expression has been associated with lignification in primary and secondary tissues. We now report cloning two differentially expressed PAL cDNAs that exhibit distinct spatial associations with CT and lignin biosynthesis in developing shoot and root tissues of aspen. PtPAL1 was expressed in certain CT-accumulating, non-lignifying cells of stems, leaves, and roots, and the pattern of PtPAL1 expression varied coordinately with that of CT accumulation along the primary to secondary growth transition in stems. PtPAL2 was expressed in heavily lignified structural cells of shoots, but was also expressed in non-lignifying cells of root tips. Evidence of a role for Pt4CL2, encoding 4-coumarate:coenzyme A ligase, in determining CT sink strength was gained from cellular co-expression analysis with PAL1 and CTs, and from experiments in which leaf wounding increased PAL1 and 4CL2 expression as well as the relative allocation of carbon to CT with respect to phenolic glycoside, the dominant phenolic sink in aspen leaves. Leaf wounding also increased PAL2 and lignin pathway gene expression, but to a smaller extent. The absence of PAL2 in most CT-accumulating cells provides in situ support for the idea that PAL isoforms function in specific metabolic milieus.