Individual variation in fetal hemoglobin (HbF, ␣2␥2) response underlies the remarkable diversity in phenotypic severity of sickle cell disease and ␤ thalassemia. HbF levels and HbF-associated quantitative traits (e.g., F cell levels) are highly heritable. We have previously mapped a major quantitative trait locus (QTL) controlling F cell levels in an extended Asian-Indian kindred with ␤ thalassemia to a 1.5-Mb interval on chromosome 6q23, but the causative gene(s) are not known. The QTL encompasses several genes including HBS1L, a member of the GTP-binding protein family that is expressed in erythroid progenitor cells. In this high-resolution association study, we have identified multiple genetic variants within and 5 to HBS1L at 6q23 that are strongly associated with F cell levels in families of Northern European ancestry (P ‫؍‬ 10 ؊75 ). The region accounts for 17.6% of the F cell variance in northern Europeans. Although mRNA levels of HBS1L and MYB in erythroid precursors grown in vitro are positively correlated, only HBS1L expression correlates with high F cell alleles. The results support a key role for the HBS1L-related genetic variants in HbF control and illustrate the biological complexity of the mechanism of 6q QTL as a modifier of fetal hemoglobin levels in the ␤ hemoglobinopathies.

Limited microRNAs (miRNAs, miRs) have been reported to be necessary for exercise-induced cardiac growth and essential for protection against pathological cardiac remodeling. Here we determined members of the miR-17-92 cluster and their passenger miRNAs expressions in two distinct murine exercise models and found that miR-17-3p was increased in both. miR-17-3p promoted cardiomyocyte hypertrophy, proliferation, and survival. TIMP-3 was identified as a direct target gene of miR-17-3p whereas PTEN was indirectly inhibited by miR-17-3p. Inhibition of miR-17-3p in vivo attenuated exercise-induced cardiac growth including cardiomyocyte hypertrophy and expression of markers of myocyte proliferation. Importantly, mice injected with miR-17-3p agomir were protected from adverse remodeling after cardiac ischemia/reperfusion injury. Collectively, these data suggest that miR-17-3p contributes to exercise-induced cardiac growth and protects against adverse ventricular remodeling. miR-17-3p may represent a novel therapeutic target to promote functional recovery after cardiac ischemia/reperfusion.

The histone variants H3.3 and H2A.Z have recently emerged as two of the most important features in transcriptional regulation, the molecular mechanism of which still remains poorly understood. In this study, we investigated the regulation of H3.3 and H2A.Z on chromatin dynamics during transcriptional activation. Our in vitro biophysical and biochemical investigation showed that H2A.Z promoted chromatin compaction and repressed transcriptional activity. Surprisingly, with only four to five amino acid differences from the canonical H3, H3.3 greatly impaired higher-ordered chromatin folding and promoted gene activation, although it has no significant effect on the stability of mononucleosomes. We further demonstrated that H3.3 actively marks enhancers and determines the transcriptional potential of retinoid acid (RA)-regulated genes via creating an open chromatin signature that enables the binding of RAR/RXR. Additionally, the H3.3-dependent recruitment of H2A.Z on promoter regions resulted in compaction of chromatin to poise transcription, while RA induction results in the incorporation of H3.3 on promoter regions to activate transcription via counteracting H2A.Zmediated chromatin compaction. Our results provide key insights into the mechanism of how histone variants H3.3 and H2A.Z function together to regulate gene transcription via the modulation of chromatin dynamics over the enhancer and promoter regions.

The purpose of this study was to conduct a comprehensive study of the clinical correlation between the alpha-fetoprotein (AFP) level at diagnosis and pathological grades, progression, and survival of patients with hepatocellular carcinoma (HCC). A total of 78,743 patients in Surveillance, Epidemiology, and End Results Program (SEER)-registered HCC was analyzed. The AFP test results for patients with HCC were mainly recorded as AFP-negative and AFP-positive. Logistic regression analysis revealed that the AFP level at diagnosis was an independent risk factor of pathological grade (odds ratio [OR], 2.559; 95% confidence interval [CI], 2.075–3.157; P < 0.001), TNM-7 stage (OR, 2.794; CI, 2.407–3.242; P < 0.001), and tumor size (OR, 1.748; 95% CI, 1.574–1.941; P < 0.001). Multivariable Cox regression analyses identified AFP level as an independent predictor of survival risk of patients with HCC who did not undergo surgery (hazard ratio [HR], 1.660; 95% CI, 1.534–1.797; P < 0.001), and those who underwent surgery (HR, 1.534; 95% CI, 1.348–1.745; P < 0.001). The AFP level at diagnosis was an independent risk predictor associated with pathological grade, progression, and survival. Further, surgery may not significantly reverse the adverse effects of AFP-positive compared with AFP-negative.