Knockdown of NYGGF4 (PID1) rescues insulin resistance and mitochondrial dysfunction induced by FCCP in 3T3-L1 adipocytes

Regional differences in progenitor metabolism shape brain growth during development

Mammals have particularly large forebrains compared with other brain parts, yet the developmental mechanisms underlying this regional expansion remain poorly understood. Here, we provide a single-cell-resolution birthdate atlas of the mouse brain (www.neurobirth.org), which reveals that while hindbrain neurogenesis is transient and restricted to early development, forebrain neurogenesis is temporally sustained through reduced consumptive divisions of ventricular zone progenitors. This atlas additionally reveals region-specific patterns of direct and indirect neurogenesis. Using single-cell RNA sequencing, we identify evolutionarily conserved cell-cycle programs and metabolism-related molecular pathways that control regional temporal windows of proliferation. We identify the late neocortex-enriched mitochondrial protein FAM210B as a key regulator using in vivo gain- and loss-of-function experiments. FAM210B elongates mitochondria and increases lactate production, which promotes progenitor self-replicative divisions and, ultimately, the larger clonal size of their progeny. Together, these findings indicate that spatiotemporal heterogeneity in mitochondrial function regulates regional progenitor cycling behavior and associated clonal neuronal production during brain development.

Genome-Wide Association Analysis Reveals Novel Loci Related with Visual Score Traits in Nellore Cattle Raised in Pasture-Based Systems

Body conformation traits assessed based on visual scores are widely used in Zebu cattle breeding programs. The aim of this study was to identify genomic regions and biological pathways associated with body conformation (CONF), finishing precocity (PREC), and muscling (MUSC) in Nellore cattle. The measurements based on visual scores were collected in 20,807 animals raised in pasture-based systems in Brazil. In addition, 2775 animals were genotyped using a 35 K SNP chip, which contained 31,737 single nucleotide polymorphisms after quality control. Single-step GWAS was performed using the BLUPF90 software while candidate genes were identified based on the Ensembl Genes 69. PANTHER and REVIGO platforms were used to identify key biological pathways and STRING to create gene networks. Novel candidate genes were revealed associated with CONF, including ALDH9A1, RXRG, RAB2A, and CYP7A1, involved in lipid metabolism. The genes associated with PREC were ELOVL5, PID1, DNER, TRIP12, and PLCB4, which are related to the synthesis of long-chain fatty acids, lipid metabolism, and muscle differentiation. For MUSC, the most important genes associated with muscle development were SEMA6A, TIAM2, UNC5A, and UIMC1. The polymorphisms identified in this study can be incorporated in commercial genotyping panels to improve the accuracy of genomic evaluations for visual scores in beef cattle.

GM13133 is a negative regulator in mouse white adipocytes differentiation and drives the characteristics of brown adipocytes

Obesity is tightly associated with the disturbance of white adipose tissue storing excess energy. Thermogenic adipocytes (brown and beige) exert a critical role of oxidizing nutrients at the high rates through non-shivering thermogenesis. The recruitment of brown characteristics in white adipocytes, termed browning, has been considered as a promising strategy for treating obesity and associated metabolic complications. Recently, long noncoding RNAs play a crucial role in regulating tissue development and participating in disease pathogenesis, yet their effects on the conversion of white into brown-like adipocytes and thermogenic function were not totally understood. Here, we identified a mouse brown adipose specific expressed lncRNA, termed GM13133. Moreover, a considerable amount of GM13133 is expressed in adipocytes and actively modulated by cold, β₃ -adrenergic agonist and cAMP stimuli, implying a potential role in the conversion from white to brown adipocytes. Overexpression of GM13133 did not affect the proliferation of mouse white pre-adipocytes, but inhibited white adipocyte differentiation by decreasing lipid accumulation. The forced expression of GM13133 also significantly drove the conversion of white into brown-like adipocytes with the enhanced mitochondrial biogenesis and the induced expression of brown adipocytes specific markers. A global mRNA analysis further indicated the possible regulatory role of cAMP signaling pathway in GM13133 mediated white-to-brown adipocytes conversion. Our results identified a lncRNA-mediated modulation in primary mouse white adipocyte differentiation and indicate the functional significance of GM13133 in promoting browning of white adipocytes and maintenance of thermogenesis, further providing a potential strategy to treating obesity.

PID1 increases chemotherapy-induced apoptosis in medulloblastoma and glioblastoma cells in a manner that involves NFκB

Phosphotyrosine Interaction Domain containing 1 (PID1; NYGGF4) inhibits growth of medulloblastoma, glioblastoma and atypical teratoid rhabdoid tumor cell lines. PID1 tumor mRNA levels are highly correlated with longer survival in medulloblastoma and glioma patients, suggesting their tumors may have been more sensitive to therapy. We hypothesized that PID1 sensitizes brain tumors to therapy. We found that PID1 increased the apoptosis induced by cisplatin and etoposide in medulloblastoma and glioblastoma cell lines. PID1 siRNA diminished cisplatin-induced apoptosis, suggesting that PID1 is required for cisplatin-induced apoptosis. Etoposide and cisplatin increased NFκB promoter reporter activity and etoposide induced nuclear translocation of NFκB. Etoposide also increased PID1 promoter reporter activity, PID1 mRNA, and PID1 protein, which were diminished by NFκB inhibitors JSH-23 and Bay117082. However, while cisplatin increased PID1 mRNA, it decreased PID1 protein. This decrease in PID1 protein was mitigated by the proteasome inhibitor, bortezomib, suggesting that cisplatin induced proteasome dependent degradation of PID1. These data demonstrate for the first time that etoposide- and cisplatin-induced apoptosis in medulloblastoma and glioblastoma cell lines is mediated in part by PID1, involves NFκB, and may be regulated by proteasomal degradation. This suggests that PID1 may contribute to responsiveness to chemotherapy.

Silencing miR-106b improves palmitic acid-induced mitochondrial dysfunction and insulin resistance in skeletal myocytes

MicroRNA‑106b (miR‑106b) is reported to correlate closely with skeletal muscle insulin resistance. In the current study the effect of miR‑106b on palmitic acid (PA)‑induced mitochondrial dysfunction and insulin resistance was investigated in C2C12 myotubes via the silencing of miR‑106b. MiR‑106b expression was increased under PA treatment, while miR‑106b loss of function improved insulin sensitivity by upregulating its target mitofusin‑2 (Mfn2) in C2C12 myocytes. Furthermore, miR‑106b loss of function partly improved mitochondrial morphological lesions and increased the levels of mitochondial DNA and intracellular adenosine triphosphate that had been impaired by PA exposure in C2C12 myocytes. MiR‑106b loss of function attenuated the levels of intracellular reactive oxygen species (ROS), and upregulated the expression levels of the estrogen‑related receptor (ERR)‑α/peroxisome proliferative activated receptor γ coactivator (PGC)‑1α/Mfn2 axis under PA exposure. In addition, miR‑106b negatively regulated skeletal muscle mitochondrial function and insulin sensitivity under PA‑induced insulin resistance by targeting Mfn2, which may be associated with reduced ROS and upregulation of the ERR‑α/PGC‑1α/Mfn2 axis.

PID1 (NYGGF4), a new growth-inhibitory gene in embryonal brain tumors and gliomas

PURPOSE

We present here the first report of PID1 (Phosphotyrosine Interaction Domain containing 1; NYGGF4) in cancer. PID1 was identified in 2006 as a gene that modulates insulin signaling and mitochondrial function in adipocytes and muscle cells.

EXPERIMENTAL DESIGN AND RESULTS

Using four independent medulloblastoma datasets, we show that mean PID1 mRNA levels were lower in unfavorable medulloblastomas (groups 3 and 4, and anaplastic histology) compared with favorable medulloblastomas (SHH and WNT groups, and desmoplastic/nodular histology) and with fetal cerebellum. In two large independent glioma datasets, PID1 mRNA was lower in glioblastomas (GBM), the most malignant gliomas, compared with other astrocytomas, oligodendrogliomas and nontumor brains. Neural and proneural GBM subtypes had higher PID1 mRNA compared with classical and mesenchymal GBM. Importantly, overall survival and radiation-free progression-free survival were longer in medulloblastoma patients whose tumors had higher PID1 mRNA (univariate and multivariate analyses). Higher PID1 mRNA also correlated with longer overall survival in patients with glioma and GBM. In cell culture, overexpression of PID1 inhibited colony formation in medulloblastoma, atypical teratoid rhabdoid tumor (ATRT), and GBM cell lines. Increasing PID1 also increased cell death and apoptosis, inhibited proliferation, induced mitochondrial depolaization, and decreased serum-mediated phosphorylation of AKT and ERK in medulloblastoma, ATRT, and/or GBM cell lines, whereas siRNA to PID1 diminished mitochondrial depolarization.

CONCLUSIONS

These data are the first to link PID1 to cancer and suggest that PID1 may have a tumor inhibitory function in these pediatric and adult brain tumors.

Differential regulation of γ-glutamyltransferase and glutamate cysteine ligase expression after mitochondrial uncoupling: γ-glutamyltransferase is regulated in an Nrf2- and NFκB-independent manner

The enzymes γ-glutamyltransferase (GGT) and glutamate cysteine ligase (GCL) have important roles in glutathione (GSH) homeostasis, and both are frequently upregulated after acute oxidative stress. Mitochondria are major producers of ROS, and incubating the colorectal adenocarcinoma cell line HT-29 cells with mitochondrial uncouplers significantly increased endogenous ROS as well as mRNA for both GGT and GCLC (the catalytic subunit of GCL). However, no elevation in GGT protein or activity was detected, in contrast to the increased levels of GCLC protein found. The uncouplers initiated endoplasmic reticulum (ER) stress, as demonstrated by highly increased levels of CHOP and GRP78 mRNA. Using inhibitors of proteasomes and ER-associated degradation (ERAD) together with a mitochondrial uncoupler, increased GGT protein and activity levels were obtained indicating that GGT may be a substrate for ERAD. Uncoupling increased the mRNA levels of the two redox-regulated transcription factors Nrf2 and NFκB. Using siRNA to suppress Nrf2 and NFκB expression, downregulation of GCLC expression both at the basal level and after mitochondrial uncoupling was achieved. In contrast, the expression level of GGT was not affected by this treatment. These data strongly indicate a discrepancy between the regulation of GCLC and of GGT following the oxidative stress situation due to mitochondrial uncoupling. Both the enzymes are considered to be part of the cellular antioxidant system; however, the role of GGT as a consistent oxidative response parameter needs to be reevaluated.