Diurnal regulation of alternative splicing associated with thermotolerance in rice by two glycine-rich RNA-binding proteins.

Rice (Oryza sativa L.) production is threatened by global warming associated with extreme high temperatures, and rice heat sensitivity is differed when stress occurs between daytime and nighttime. However, the underlying molecular mechanism are largely unknown. We show here that two glycine-rich RNA binding proteins, OsGRP3 and OsGRP162, are required for thermotolerance in rice, especially at nighttime. The rhythmic expression of OsGRP3/OsGRP162 peaks at midnight, and at these coincident times, is increased by heat stress. This is largely dependent on the evening complex component OsELF3-2. We next found that the double mutant of OsGRP3/OsGRP162 is strikingly more sensitive to heat stress in terms of survival rate and seed setting rate when comparing to the wild-type plants. Interestingly, the defect in thermotolerance is more evident when heat stress occurred in nighttime than that in daytime. Upon heat stress, the double mutant of OsGRP3/OsGRP162 displays globally reduced expression of heat-stress responsive genes, and increases of mRNA alternative splicing dominated by exon-skipping. This study thus reveals the important role of OsGRP3/OsGRP162 in thermotolerance in rice, and unravels the mechanism on how OsGRP3/OsGRP162 regulate thermotolerance in a diurnal manner.

Rescuing the Golgi from heat damages by ATG8: restoration rather than clean-up.

High temperature stress poses significant adverse effects on crop yield and quality. Yet the molecular mechanisms underlying heat stress tolerance in plants/crops, especially regarding the organellar remodeling and homeostasis, are largely unknown. In a recent study, Zhou et al. reported that autophagy-related 8 (ATG8), a famous regulator involved in autophagy, plays a new role in Golgi restoration upon heat stress. Golgi apparatus is vacuolated following short-term acute heat stress, and ATG8 is translocated to the dilated Golgi membrane and interacts with CLATHRIN LIGHT CHAIN 2 (CLC2) to facilitate Golgi restoration, which is dependent on the ATG conjugation system, but not of the upstream autophagic initiators. These exciting findings broaden the fundamental role of ATG8, and elucidate the organelle-level restoration mechanism of Golgi upon heat stress in plants.

Timing to grow: roles of clock in thermomorphogenesis.

Plants coordinate their growth and developmental programs with changes in temperature. This process is termed thermomorphogenesis. The underlying molecular mechanisms have begun to emerge in these nonstressful responses to adjustments in prevailing temperature. The circadian clock is an internal timekeeper that ensures growth, development, and fitness across a wide range of environmental conditions and it responds to thermal changes. Here, we highlight how the circadian clock gates thermoresponsive hypocotyl growth in plants, with an emphasis on different action mode of evening complex (EC) in thermomorphogenesis. We also discuss the biochemical and molecular mechanisms of EC in transducing temperature signals to the key integrator PIF4. This provides future perspectives on unanswered questions on EC-associated thermomorphogenesis.

A novel five-gene signature predicts overall survival of patients with hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is one of the most common public health challenges, worldwide. Because of molecular complexity and tumor heterogeneity, there are no effective predictive models for prognosis of HCC. This underlines the unmet need for accurate prognostic models for HCC. Analysis of GSE14520 data from gene omnibus (GEO) database identified multiple differentially expressed mRNAs (DEMs) between HCC and normal tissues. After randomly stratifying the patients into the training and testing groups, we performed univariate, lasso, and multivariable Cox regression analyses to delineate the prognostic gene signature in training set. We then used Kaplan-Meier plot, time-dependent receiver operating characteristic (ROC), multivariable Cox regression analysis of clinical information, nomogram, and decision curve analysis (DCA) to evaluate the predictive and overall survival value of a novel five-gene signature (CNIH4, SOX4, SPP1, SORBS2, and CCL19) within and across sets, separately and combined. We also validated the prognostic value of the five-gene signature using The Cancer Genome Atlas-Liver Hepatocellular Carcinoma (TCGA-LIHC), GSE54236 and International Cancer Genome Consortium (ICGC) sets. Multivariable Cox regression analysis revealed that the five-gene signature and tumor node metastasis (TNM) stage were independent prognostic factors for overall survival of HCC patients in GSE14520 and TCGA-LIHC. Combining TNM stage clinical pathological parameters and nomogram greatly improved the prognosis prediction of HCC. Further gene set enrichment analysis (GSEA) revealed enrichment of KEGG pathways related to cell cycle in the high-risk group and histidine metabolism in the low-risk group. Finally, all these five mRNAs are overexpressed between 12 pairs of HCC and adjacent normal tissues by quantitative real-time PCR validation. In brief, a five-gene prognostic signature and a nomogram were identified and constructed, respectively, and further validated for their HCC prognostic value. The five-gene risk score together with TNM stage models could aid in rationalizing customized therapies in HCC patients.