Alternative Splicing and Nonsense-Mediated RNA Decay Contribute to the Regulation of SHOX Expression

The human SHOX gene is composed of seven exons and encodes a paired-related homeodomain transcription factor. SHOX mutations or deletions have been associated with different short stature syndromes implying a role in growth and bone formation. During development, SHOX is expressed in a highly specific spatiotemporal expression pattern, the underlying regulatory mechanisms of which remain largely unknown. We have analysed SHOX expression in diverse embryonic, fetal and adult human tissues and detected expression in many tissues that were not known to express SHOX before, e.g. distinct brain regions. By using RT-PCR and comparing the results with RNA-Seq data, we have identified four novel exons (exon 2a, 7-1, 7-2 and 7-3) contributing to different SHOX isoforms, and also established an expression profile for the emerging new SHOX isoforms. Interestingly, we found the exon 7 variants to be exclusively expressed in fetal neural tissues, which could argue for a specific role of these variants during brain development. A bioinformatical analysis of the three novel 3′UTR exons yielded insights into the putative role of the different 3′UTRs as targets for miRNA binding. Functional analysis revealed that inclusion of exon 2a leads to nonsense-mediated RNA decay altering SHOX expression in a tissue and time specific manner. In conclusion, SHOX expression is regulated by different mechanisms and alternative splicing coupled with nonsense-mediated RNA decay constitutes a further component that can be used to fine tune the SHOX expression level

Chromatin organisation and cancer prognosis: a pan-cancer study

Background: Chromatin organisation affects gene expression and regional mutation frequencies and contributes to carcinogenesis. Aberrant organisation of DNA has been correlated with cancer prognosis in analyses of the chromatin component of tumour cell nuclei using image texture analysis. As yet, the methodology has not been sufficiently validated to permit its clinical application. We aimed to define and validate a novel prognostic biomarker for the automatic detection of heterogeneous chromatin organisation. Methods Machine learning algorithms analysed the chromatin organisation in 461 000 images of tumour cell nuclei stained for DNA from 390 patients (discovery cohort) treated for stage I or II colorectal cancer at the Aker University Hospital (Oslo, Norway). The resulting marker of chromatin heterogeneity, termed Nucleotyping, was subsequently independently validated in six patient cohorts: 442 patients with stage I or II colorectal cancer in the Gloucester Colorectal Cancer Study (UK); 391 patients with stage II colorectal cancer in the QUASAR 2 trial; 246 patients with stage I ovarian carcinoma; 354 patients with uterine sarcoma; 307 patients with prostate carcinoma; and 791 patients with endometrial carcinoma. The primary outcome was cancer-specific survival. Findings: In all patient cohorts, patients with chromatin heterogeneous tumours had worse cancer-specific survival than patients with chromatin homogeneous tumours (univariable analysis hazard ratio [HR] 1·7, 95% CI 1·2–2·5, in the discovery cohort; 1·8, 1·0–3·0, in the Gloucester validation cohort; 2·2, 1·1–4·5, in the QUASAR 2 validation cohort; 3·1, 1·9–5·0, in the ovarian carcinoma cohort; 2·5, 1·8–3·4, in the uterine sarcoma cohort; 2·3, 1·2–4·6, in the prostate carcinoma cohort; and 4·3, 2·8–6·8, in the endometrial carcinoma cohort). After adjusting for established prognostic patient characteristics in multivariable analyses, Nucleotyping was prognostic in all cohorts except for the prostate carcinoma cohort (HR 1·7, 95% CI 1·1–2·5, in the discovery cohort; 1·9, 1·1–3·2, in the Gloucester validation cohort; 2·6, 1·2–5·6, in the QUASAR 2 cohort; 1·8, 1·1–3·0, for ovarian carcinoma; 1·6, 1·0–2·4, for uterine sarcoma; 1·43, 0·68–2·99, for prostate carcinoma; and 1·9, 1·1–3·1, for endometrial carcinoma). Chromatin heterogeneity was a significant predictor of cancer-specific survival in microsatellite unstable (HR 2·9, 95% CI 1·0–8·4) and microsatellite stable (1·8, 1·2–2·7) stage II colorectal cancer, but microsatellite instability was not a significant predictor of outcome in chromatin homogeneous (1·3, 0·7–2·4) or chromatin heterogeneous (0·8, 0·3–2·0) stage II colorectal cancer. Interpretation: The consistent prognostic prediction of Nucleotyping in different biological and technical circumstances suggests that the marker of chromatin heterogeneity can be reliably assessed in routine clinical practice and could be used to objectively assist decision making in a range of clinical settings. An immediate application would be to identify high-risk patients with stage II colorectal cancer who might have greater absolute benefit from adjuvant chemotherapy. Clinical trials are warranted to evaluate the survival benefit and cost-effectiveness of using Nucleotyping to guide treatment decisions in multiple clinical settings

Dynamic control over catalytic function using responsive bisthiourea catalysts

Two novel bisthiourea molecular motor-based catalysts were designed and their dynamic control of activity and stereoselectivity in the Henry reaction using heat and light as external stimuli was investigated. Enantioselective organocatalysis studies established that a basic functional group is not required within the catalyst core to effect efficient dual stereocontrol, illustrating novel stimuli responsive organocatalysts