OCT4 induces long-lived dedifferentiated kidney progenitors poised to redifferentiate in 3D kidney spheroids.

Upscaling of kidney epithelial cells is crucial for renal regenerative medicine. Nonetheless, the adult kidney lacks a distinct stem cell hierarchy, limiting the ability to long-term propagate clonal populations of primary cells that retain renal identity. Toward this goal, we tested the paradigm of shifting the balance between differentiation and stemness in the kidney by introducing a single pluripotency factor, OCT4. Here we show that ectopic expression of OCT4 in human adult kidney epithelial cells (hKEpC) induces the cells to dedifferentiate, stably proliferate, and clonally emerge over many generations. Control hKEpC dedifferentiate, assume fibroblastic morphology, and completely lose clonogenic capacity. Analysis of gene expression and histone methylation patterns revealed that OCT4 represses the HNF1B gene module, which is critical for kidney epithelial differentiation, and concomitantly activates stemness-related pathways. OCT4-hKEpC can be long-term expanded in the dedifferentiated state that is primed for renal differentiation. Thus, when expanded OCT4-hKEpC are grown as kidney spheroids (OCT4-kSPH), they reactivate the HNF1B gene signature, redifferentiate, and efficiently generate renal structures in vivo. Hence, changes occurring in the cellular state of hKEpC following OCT4 induction, long-term propagation, and 3D aggregation afford rapid scale-up technology of primary renal tissue-forming cells.

Resting and Exercise Energy Metabolism After Liver Transplantation for Nonalcoholic Steatohepatitis.

BACKGROUND: Nonalcoholic steatohepatitis (NASH) is a leading indication for liver transplantation (LT). We hypothesized that weight gain after LT may be exacerbated by reduced metabolic rates due to the LT procedure, particularly during exercise. We aimed to compare resting and exercise energy expenditure between patients transplanted for NASH and nontransplant nonalcoholic fatty liver disease (NAFLD) subjects. METHODS: NASH LT recipients (>1-year post, n = 14) and NAFLD controls (n = 13) underwent analysis of body composition, resting energy expenditure (REE), and exercise energy expenditure (VO2max), the latter using a ramped-Bruce protocol assessed by expired gas analysis and peak heart rate. RESULTS: Participants were mean 61.5 ± 7.9 years, 48.1% men, and 66.7% white. Baseline comorbidities were similar between groups. Among men, mean REE adjusted for total (17.7 vs 18.8, P = 0.87) and lean body mass (23.5 vs 26.9, P = 0.26), as well as VO2 (20.1 vs 23.9, P = 0.29), was lower in NASH LT recipients compared with NAFLD controls, respectively, although not statistically significant. However, female NASH LT recipients had significantly lower mean REE than NAFLD controls when adjusted for total (14.2 vs 18.9, P = 0.01) and lean body mass (19.3 vs 26.5, P = 0.002), as well as significantly lower VO2max (14.4 vs 20.6, P = 0.017). CONCLUSIONS: NASH LT recipients, particularly women, have lower REE and exercise energy expenditure compared with nontransplant NAFLD patients. More aggressive diet and exercise programs for post-LT NASH recipients to account for reduced resting and exercise metabolic rates may attenuate weight gain in this vulnerable population.

The linker histone H1.0 generates epigenetic and functional intratumor heterogeneity.

Tumors comprise functionally diverse subpopulations of cells with distinct proliferative potential. Here, we show that dynamic epigenetic states defined by the linker histone H1.0 determine which cells within a tumor can sustain the long-term cancer growth. Numerous cancer types exhibit high inter- and intratumor heterogeneity of H1.0, with H1.0 levels correlating with tumor differentiation status, patient survival, and, at the single-cell level, cancer stem cell markers. Silencing of H1.0 promotes maintenance of self-renewing cells by inducing derepression of megabase-sized gene domains harboring downstream effectors of oncogenic pathways. Self-renewing epigenetic states are not stable, and reexpression of H1.0 in subsets of tumor cells establishes transcriptional programs that restrict cancer cells' long-term proliferative potential and drive their differentiation. Our results uncover epigenetic determinants of tumor-maintaining cells.

HP1 is involved in regulating the global impact of DNA methylation on alternative splicing.

The global impact of DNA methylation on alternative splicing is largely unknown. Using a genome-wide approach in wild-type and methylation-deficient embryonic stem cells, we found that DNA methylation can either enhance or silence exon recognition and affects the splicing of more than 20% of alternative exons. These exons are characterized by distinct genetic and epigenetic signatures. Alternative splicing regulation of a subset of these exons can be explained by heterochromatin protein 1 (HP1), which silences or enhances exon recognition in a position-dependent manner. We constructed an experimental system using site-specific targeting of a methylated/unmethylated gene and demonstrate a direct causal relationship between DNA methylation and alternative splicing. HP1 regulates this gene's alternative splicing in a methylation-dependent manner by recruiting splicing factors to its methylated form. Our results demonstrate DNA methylation's significant global influence on mRNA splicing and identify a specific mechanism of splicing regulation mediated by HP1.

Growth and asymmetry of soil microfungal colonies from "Evolution Canyon," Lower Nahal Oren, Mount Carmel, Israel.

BACKGROUND: Fluctuating asymmetry is a contentious indicator of stress in populations of animals and plants. Nevertheless, it is a measure of developmental noise, typically obtained by measuring asymmetry across an individual organism's left-right axis of symmetry. These individual, signed asymmetries are symmetrically distributed around a mean of zero. Fluctuating asymmetry, however, has rarely been studied in microorganisms, and never in fungi. OBJECTIVE AND METHODS: We examined colony growth and random phenotypic variation of five soil microfungal species isolated from the opposing slopes of "Evolution Canyon," Mount Carmel, Israel. This canyon provides an opportunity to study diverse taxa inhabiting a single microsite, under different kinds and intensities of abiotic and biotic stress. The south-facing "African" slope of "Evolution Canyon" is xeric, warm, and tropical. It is only 200 m, on average, from the north-facing "European" slope, which is mesic, cool, and temperate. Five fungal species inhabiting both the south-facing "African" slope, and the north-facing "European" slope of the canyon were grown under controlled laboratory conditions, where we measured the fluctuating radial asymmetry and sizes of their colonies. RESULTS: Different species displayed different amounts of radial asymmetry (and colony size). Moreover, there were highly significant slope by species interactions for size, and marginally significant ones for fluctuating asymmetry. There were no universal differences (i.e., across all species) in radial asymmetry and colony size between strains from "African" and "European" slopes, but colonies of Clonostachys rosea from the "African" slope were more asymmetric than those from the "European" slope. CONCLUSIONS AND SIGNIFICANCE: Our study suggests that fluctuating radial asymmetry has potential as an indicator of random phenotypic variation and stress in soil microfungi. Interaction of slope and species for both growth rate and asymmetry of microfungi in a common environment is evidence of genetic differences between the "African" and "European" slopes of "Evolution Canyon."

Amygdala volumes in childhood absence epilepsy.

Abnormal amygdala volumes in pediatric mood-anxiety disorders and attention deficit hyperactivity disorder (ADHD), as well as high rates of these diagnoses in childhood absence epilepsy (CAE), prompted this study of amygdala volume in CAE. Twenty-six children with CAE and 23 normal children, aged 6.6-15.8 years, underwent MRI at 1.5 T. The tissue imaged with MRI was segmented, and amygdala volumes were obtained by manual tracings. There were no significant amygdala volume differences between the CAE and normal groups. Within the CAE group, however, the children with ADHD had significantly smaller amygdala volumes than the subjects with CAE with no psychopathology and those with mood/anxiety diagnoses. There was also a significant relationship between higher seizure frequency and greater amygdala asymmetry in the epilepsy group. Given ongoing development of the amygdala during late childhood and adolescence, despite the lack of significant group differences in amygdala volumes, the association of amygdala volume abnormalities with ADHD and seizure frequency implies a possible impact of the disorder on amygdala development and CAE-associated comorbidities, such as ADHD.