OBJECTIVE:To identify a new genetic cause of distal hereditary motor neuropathy (dHMN), which is also known as a variant of Charcot-Marie-Tooth disease (CMT), in a Chinese family. METHODS:We investigated a Chinese family with dHMN clinically, electrophysiologically, and genetically. We screened for the mutations of 28 CMT or related pathogenic genes using an originally designed microarray resequencing DNA chip. RESULTS:Investigation of the family history revealed an autosomal dominant transmission pattern. The clinical features of the family included mild weakness and wasting of the distal muscles of the lower limb and foot deformity, without clinical sensory involvement. Electrophysiologic studies revealed motor neuropathy. MRI of the lower limbs showed accentuated fatty infiltration of the gastrocnemius and vastus lateralis muscles. All 4 affected family members had a heterozygous missense mutation c.2677G>A (p.D893N) of alanyl-tRNA synthetase (AARS), which was not found in the 4 unaffected members and control subjects. CONCLUSION:An AARS mutation caused dHMN in a Chinese family. AARS mutations result in not only a CMT phenotype but also a dHMN phenotype.

RNA interference holds the promise to knock down expression of every cancer gene. Both academic laboratories and pharmaceutical companies have committed heavily on manpower and financial resources to develop small interfering RNA (siRNA) cancer therapeutics over the last decade. Although significant advances have been made in the design of siRNA therapeutics and mechanism of action on cancer cell killing, there are still many hurdles to overcome including effective delivery of therapeutics in vivo. Nanotechnology has had an important role in the development of delivery vectors so far. This article summarizes current nanovectors for siRNA delivery, discusses technical challenges in overcoming biological barriers, and introduces the multistage vector system for tumor-specific delivery.Cancer Gene Therapy advance online publication, 4 May 2012; doi:10.1038/cgt.2012.22.

During the past four decades, there has been an increase in the incidence rate of male reproductive disorders in some, but not all, Western countries. The observed increase in the prevalence of male reproductive disorders is suspected to be ascribable to environmental factors as the increase has been too rapid to be explained by genetics alone. To study the association between complex chemical exposures of humans and congenital cryptorchidism, the most common malformation of the male genitalia, we measured 121 environmental chemicals with suspected or known endocrine disrupting properties in 130 breast milk samples from Danish and Finnish mothers. Half the newborns were healthy controls, whereas the other half was boys with congenital cryptorchidism. The measured chemicals included polychlorinated biphenyls (PCBs), polybrominated diphenyl-ethers, dioxins (OCDD/PCDFs), phthalates, polybrominated biphenyls and organochlorine pesticides. Computational analysis of the data was performed using logistic regression and three multivariate machine learning classifiers. Furthermore, we performed systems biology analysis to explore the chemical influence on a molecular level. After correction for multiple testing, exposure to nine chemicals was significantly different between the cases and controls in the Danish cohort, but not in the Finnish cohort. The multivariate analysis indicated that Danish samples exhibited a stronger correlation between chemical exposure patterns in breast milk and cryptorchidism than Finnish samples. Moreover, PCBs were indicated as having a protective effect within the Danish cohort, which was supported by molecular data recovered through systems biology. Our results lend further support to the hypothesis that the mixture of environmental chemicals may contribute to observed adverse trends in male reproductive health.

Breast cancer accounted for 15 per cent of total cancer deaths in female patients in 2010. Although significant progress has been made in treating early-stage breast cancer patients, there is still no effective therapy targeting late-stage metastatic breast cancers except for the conventional chemotherapy interventions. Until effective therapy for later-stage cancers emerges, the identification of biomarkers for the early detection of tumour metastasis continues to hold the key to successful management of breast cancer therapy. Our study concentrated on the low molecular weight (LMW) region of the serum protein and the information it contains for identifying biomarkers that could reflect the ongoing physiological state of all tissues. Owing to technical difficulties in harvesting LMW species, studying these proteins/peptides has been challenging until now. In our study, we have recently developed nanoporous chip-based technologies to separate small proteins/peptides from the large proteins in serum. We used nanoporous silica chips, with a highly periodic nanostructure and uniform pore size distribution, to isolate LMW proteins and peptides from the serum of nude mice with MDA-MB-231 human breast cancer lung metastasis. By matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and biostatistical analysis, we were able to identify protein signatures unique to different stages of cancer development. The approach and results reported in this study possess a significant potential for the discovery of proteomic biomarkers that may significantly enhance personalized medicine targeted at metastatic breast cancer.

X-ray micro-CT is an important imaging tool for biomedical researchers. Our group recently proposed a hybrid true-color micro-CT system to improve contrast resolution with lower system cost and radiation dose. The system incorporates an energy-resolved photon-counting true-color detector into a conventional micro-CT configuration, and can be used for material decomposition. In this paper, we demonstrate an interior color-CT image reconstruction algorithm developed for this hybrid true-color micro-CT system. A compressive sensing-based statistical interior tomography method is employed to reconstruct each channel in the local spectral imaging chain, where the reconstructed global gray-scale image from the conventional imaging chain served as the initial guess. Principal component analysis was used to map the spectral reconstructions into the color space. The proposed algorithm was evaluated by numerical simulations, physical phantom experiments and animal studies. The results confirm the merits of the proposed algorithm, and demonstrate the feasibility of the hybrid true-color micro-CT system. Additionally, a color diffusion phenomenon was observed whereby high quality true-color images are produced not only inside the region of interest (ROI), but also in neighboring regions. It appears harnessing this phenomena could potentially reduce the color detector size for a given ROI, further reducing system cost and radiation dose.

Cancers claim millions of lives each year. Early detection that can enable a higher chance of cure is of paramount importance to cancer patients. However, diagnostic tools for many forms of tumors have been lacking. Over the last few years, studies of chimeric RNAs as biomarkers have emerged. Numerous reports using bioinformatics and screening methodologies have described more than 30,000 expressed sequence tags (EST) or cDNA sequences as putative chimeric RNAs. While cancer cells have been well known to contain fusion genes derived from chromosomal translocations, rearrangements or deletions, recent studies suggest that trans-splicing in cells may be another source of chimeric RNA production. Unlike cis-splicing, trans-splicing takes place between two pre-mRNA molecules, which are in most cases derived from two different genes, generating a chimeric non-co-linear RNA. It is possible that trans-splicing occurs in normal cells at high frequencies but the resulting chimeric RNAs exist only at low levels. However the levels of certain RNA chimeras may be elevated in cancers, leading to the formation of fusion genes. In light of the fact that chimeric RNAs have been shown to be overrepresented in various tumors, studies of the mechanisms that produce chimeric RNAs and identification of signature RNA chimeras as biomarkers present an opportunity for the development of diagnoses for early tumor detection.[BMB reports 2012; 45(3): 133-140].

Alternative splicing plays an important role in the control of apoptosis. A number of genes related to apoptosis undergo alternative splicing. Among them, the apoptotic regulator Bcl-x produces two major isoforms, Bcl-xL and Bcl-xS, through the alternative splicing of exon 2 in its pre-mRNA. These isoforms have antagonistic function in apoptotic pathway; Bcl-xL is pro-apoptotic, while Bcl-xS is anti-apoptotic. The balanced ratio of two isoforms is important for cell survival. However, regulatory mechanisms of Bcl-x splicing remain poorly understood. Using a mini-gene system, we have found that a 105nt exonic region (E3b) located within exon 3 affects exon 2 splicing in the Bcl-x gene. Further deletion and mutagenesis studies demonstrate that this 105nt sequence contains various functional elements which promote skipping of exon 2b. One of these elements forms a stem-loop structure that stimulates skipping of exon 2b. Furthermore our results prove that the stem-loop structure functions as an enhancer in general pre-mRNA splicing. We conclude that we have identified a cis-regulatory element in exon 3 that affects splicing of exon 2 in the Bcl-x gene. This element could be potentially targeted to alter the ratio of Bcl-xL and Bcl-xS for treatment of tumors through an apoptotic pathway.

The central dogma of DNA-RNA-protein was established more than 40 years ago. However, important biological processes have been identified since the central dogma was developed. For example, methylation is important in the regulation of transcription. In contrast, proteins, are more complex due to modifications such as phosphorylation, glycosylation, ubiquitination, or cleavage. RNA is the mediator between DNA and protein, but it can also be modulated at several levels. Among the most profound discoveries of RNA regulation is RNA splicing. It has been estimated that 80% of pre-mRNA undergo alternative splicing, which exponentially increases biological information flow in cellular processes. However, an increased number of regulated steps inevitably accompanies an increased number of errors. Abnormal splicing is often found in cells, resulting in protein dysfunction that causes disease. Splicing of the survival motor neuron (SMN) gene has been extensively studied during the last two decades. Accumulating knowledge on SMN splicing has led to speculation and search for spinal muscular atrophy (SMA) treatment by stimulating the inclusion of exon 7 into SMN mRNA. This mini-review summaries the latest progress on SMN splicing research as a potential treatment for SMA disease.

REV3Lp, the catalytic subunit of DNA polymerase zeta, is the major participant in translesion DNA synthesis. Recent evidence suggests that REV3L has an important role in the maintenance of genome stability despite its mutagenic characteristics. Such a function makes it a cancer susceptibility candidate gene. To investigate association between REV3L polymorphisms and lung cancer risk in a Chinese population, we first genotyped 15 common polymorphisms of the REV3L gene and found that three single nucleotide polymorphisms (rs465646, rs459809 and rs1002481) were significantly associated with lung cancer risk. One of the strongest associations observed was for the 3'-terminal untranslated region (3'UTR) 460 T>C polymorphism (rs465646)(adjusted odds ratio (OR)=0.69 for TC/CC; P=0.007, compared with TT). Similar results were obtained in a subsequent replication study (adjusted OR=0.72; P=0.016). Combined data from the two studies of 1072 lung cancer patients and 1064 cancer-free controls generated an even stronger association (adjusted OR=0.71; P=3.04 × 10(-4)). This 3'UTR 460 T>C variant was predicted to modulate the binding of several micro RNAs. Surface plasmon resonance analysis and luciferase assays showed that the T allele demonstrated a stronger binding affinity for miR-25 and miR-32, resulting in significantly weaker reporter expression levels. Additional experiments revealed that miR-25/32 could downregulate endogenous REV3L. Furthermore, the tumor-suppressing role of REV3L was confirmed by the foci formation assay. These results support our hypothesis that the REV3L rs465646 variant modifies lung cancer susceptibility in Chinese Han population by affecting miRNA-mediated gene regulation.Oncogene advance online publication, 20 February 2012; doi:10.1038/onc.2012.32.