Evolution of the human-specific microRNA miR-941

MicroRNA-mediated gene regulation is important in many physiological processes. Here we explore the roles of a microRNA, miR-941, in human evolution. We find that miR-941 emerged de novo in the human lineage, between six and one million years ago, from an evolutionarily volatile tandem repeat sequence. Its copy-number remains polymorphic in humans and shows a trend for decreasing copy-number with migration out of Africa. Emergence of miR-941 was accompanied by accelerated loss of miR-941-binding sites, presumably to escape regulation. We further show that miR-941 is highly expressed in pluripotent cells, repressed upon differentiation and preferentially targets genes in hedgehog- and insulin-signalling pathways, thus suggesting roles in cellular differentiation. Human-specific effects of miR-941 regulation are detectable in the brain and affect genes involved in neurotransmitter signalling. Taken together, these results implicate miR-941 in human evolution, and provide an example of rapid regulatory evolution in the human linage

Modulating RNA structure and catalysis: lessons from small cleaving ribozymes

RNA is a key molecule in life, and comprehending its structure/function relationships is a crucial step towards a more complete understanding of molecular biology. Even though most of the information required for their correct folding is contained in their primary sequences, we are as yet unable to accurately predict both the folding pathways and active tertiary structures of RNA species. Ribozymes are interesting molecules to study when addressing these questions because any modifications in their structures are often reflected in their catalytic properties. The recent progress in the study of the structures, the folding pathways and the modulation of the small ribozymes derived from natural, self-cleaving, RNA motifs have significantly contributed to today’s knowledge in the field

Human Papillomavirus Infection and Risk of Breast Cancer in Iran: A Meta-Analysis

Background: Breast cancer is the most common malignancy and a leading cause of death in women. Viruses are known to be the risk factors for breast cancer. Objectives: This systematic review and meta-analysis aimed to evaluate the association between human papillomavirus (HPV) and the development of breast cancer in Iranian women. Methods: The international databases, including Web of Science, Embase, PubMed, Cochrane, and Scopus, were searched in this study. Furthermore, relevant studies published on the association between HPV and breast cancer were identified using the appropriate keywords. The data were analyzed in Stata software (version 14) using the random-effects model. Results: In total, 18 studies were found eligible to be included in this study. The total sample size was determined at 2466 cases with the mean ages of 47.25 and 39.9 years for experimental and control groups. The overall findings showed a significant relationship between developing breast cancer and HPV infection. The results also revealed that the HPV infection increased the risk of breast cancer in women 5.02 fold more than those without HPV infection (95 CI: 3.46-7.29, I2=65.2, P=0.003). In addition, the prevalence of HPV infection among women with breast cancer was estimated at 25.66 (95 CI: 17.34-34.95, I2=86, P=0.000). Conclusion: HPV infections, especially high-risk HPVs, are significantly frequent in breast cancer samples and should be considered an important risk factor for developing breast cancer