Localization and Regulation of the N Terminal Splice Variant of PGC-1α in Adult Skeletal Muscle Fibers

The transcriptional coactivator peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) regulates expression of genes for metabolism and muscle fiber type. Recently, a novel splice variant of PGC-1α (NT-PGC-1α, amino acids 1–270) was cloned and found to be expressed in muscle. Here we use Flag-tagged NT-PGC-1α to examine the subcellular localization and regulation of NT-PGC-1α in skeletal muscle fibers. Flag-NT-PGC-1α is located predominantly in the myoplasm. Nuclear NT-PGC-1α can be increased by activation of protein kinase A. Activation of p38 MAPK by muscle activity or of AMPK had no effect on the subcellular distribution of NT-PGC-1α. Inhibition of CRM1-mediated export only caused relatively slow nuclear accumulation of NT-PGC-1α, indicating that nuclear export of NT-PGC-1α may be mediated by both CRM1-dependent and -independent pathways. Together these results suggest that the regulation of NT-PGC-1α in muscle fibers may be very different from that of the full-length PGC-1α, which is exclusively nuclear

FedSpeed: Larger Local Interval, Less Communication Round, and Higher Generalization Accuracy

Federated learning is an emerging distributed machine learning framework which jointly trains a global model via a large number of local devices with data privacy protections. Its performance suffers from the non-vanishing biases introduced by the local inconsistent optimal and the rugged client-drifts by the local over-fitting. In this paper, we propose a novel and practical method, FedSpeed, to alleviate the negative impacts posed by these problems. Concretely, FedSpeed applies the prox-correction term on the current local updates to efficiently reduce the biases introduced by the prox-term, a necessary regularizer to maintain the strong local consistency. Furthermore, FedSpeed merges the vanilla stochastic gradient with a perturbation computed from an extra gradient ascent step in the neighborhood, thereby alleviating the issue of local over-fitting. Our theoretical analysis indicates that the convergence rate is related to both the communication rounds $T$ and local intervals $K$ with a upper bound $\small \mathcal{O}(1/T)$ if setting a proper local interval. Moreover, we conduct extensive experiments on the real-world dataset to demonstrate the efficiency of our proposed FedSpeed, which performs significantly faster and achieves the state-of-the-art (SOTA) performance on the general FL experimental settings than several baselines. Our code is available at \url{https://github.com/woodenchild95/FL-Simulator.git}.Comment: ICLR 202

Smyd1b_tv1, a Key Regulator of Sarcomere Assembly, Is Localized on the M-Line of Skeletal Muscle Fibers

12 páginas, 7 figurasBackground Smyd1b is a member of the Smyd family that plays a key role in sarcomere assembly during myofibrillogenesis. Smyd1b encodes two alternatively spliced isoforms, smyd1b_tv1 and smyd1b_tv2, that are expressed in skeletal and cardiac muscles and play a vital role in myofibrillogenesis in skeletal muscles of zebrafish embryos. Methodology/Principal Findings To better understand Smyd1b function in myofibrillogenesis, we analyzed the subcellular localization of Smyd1b_tv1 and Smyd1b_tv2 in transgenic zebrafish expressing a myc-tagged Smyd1b_tv1 or Smyd1b_tv2. The results showed a dynamic change of their subcellular localization during muscle cell differentiation. Smyd1b_tv1 and Smyd1b_tv2 were primarily localized in the cytosol of myoblasts and myotubes at early stage zebrafish embryos. However, in mature myofibers, Smyd1b_tv1, and to a small degree of Smyd1b_tv2, exhibited a sarcomeric localization. Double staining with sarcomeric markers revealed that Smyd1b_tv1was localized on the M-lines. The sarcomeric localization was confirmed in zebrafish embryos expressing the Smyd1b_tv1-GFP or Smyd1b_tv2-GFP fusion proteins. Compared with Smyd1b_tv1, Smyd1b_tv2, however, showed a weak sarcomeric localization. Smyd1b_tv1 differs from Smyd1b_tv2 by a 13 amino acid insertion encoded by exon 5, suggesting that some residues within the 13 aa insertion may be critical for the strong sarcomeric localization of Smyd1b_tv1. Sequence comparison with Smyd1b_tv1 orthologs from other vertebrates revealed several highly conserved residues (Phe223, His224 and Gln226) and two potential phosphorylation sites (Thr221 and Ser225) within the 13 aa insertion. To determine whether these residues are involved in the increased sarcomeric localization of Smyd1b_tv1, we mutated these residues into alanine. Substitution of Phe223 or Ser225 with alanine significantly reduced the sarcomeric localization of Smyd1b_tv1. In contrast, other substitutions had no effect. Moreover, replacing Ser225 with threonine (S225T) retained the strong sarcomeric localization of Smyd1b_tv1. Conclusion/Significance Together, these data indicate that Phe223 and Ser225 are required for the M-line localization of Smyd1b_tv1.This research was supported by research grant No IS-8713-08 from the Israel Binational Agricultural Research and Development Fund, the United States (BARD), and an intercenter collaboration grant (Du-Fang) from University of Maryland Biotechnology Institute. (http://www.bard-isus.com/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewe

Diagnostic Utility of IDH1/2 Mutations to Distinguish Dedifferentiated Chondrosarcoma from Undifferentiated Pleomorphic Sarcoma of Bone

Histologically it is nearly impossible to distinguish the dedifferentiated component of dedifferentiated chondrosarcoma from undifferentiated pleomorphic sarcoma of bone when the low-grade cartilaginous component is absent. Previous studies have revealed that isocitrate dehydrogenase 1 (IDH1) and IDH2 mutations are present in a significant number of cartilaginous tumors including the majority of conventional chondrosarcoma and dedifferentiated chondrosarcomas. These mutations have not been studied in undifferentiated pleomorphic sarcomas of bone. We sought to investigate whether an IDH1 or IDH2 mutation signature could be used as a clinically diagnostic marker for the distinction of dedifferentiated component of chondrosarcoma from undifferentiated pleomorphic sarcoma of bone. Sixty-eight bone tumor cases, including 31 conventional chondrosarcomas, 23 dedifferentiated chondrosarcomas, and 14 undifferentiated pleomorphic sarcomas of bone, were collected for IDH1/2 mutation analysis either using the Qiagen IDH1/2 RGQ PCR Kit or using whole exome sequencing. IDH1/2 mutations were detected in 87% (20/23) of dedifferentiated chondrosarcomas and 30% (6/20) of conventional chondrosarcomas. No mutations were detected in the IDH1/2 codon 132 or codon 172 among 14 UPS of bone. Identification of IDH1 or IDH2 mutations supports the diagnosis of dedifferentiated chondrosarcoma rather than undifferentiated pleomorphic sarcoma of bone while also providing some insight into the pathogenesis of these two lesions

Prognostic value of E-cadherin and β-catenin in triple-negative breast cancer

© American Society for Clinical Pathology, 2016. All rights reserved. Objectives: To analyze the expression of E-cadherin and β-catenin in triple-negative breast cancer (TNBC) to assess their prognostic significance. Methods: The expression of E-cadherin and β-catenin was examined semiquantitatively and correlated with other pathologic factors and survival outcomes. Results: Of 72 consecutive TNBCs, 56% showed reduced membranous expression of E-cadherin or β-catenin, with a strong correlation to each other. Of the clinicopathologic factors analyzed, tumor size and nodal status were significantly associated with overall survival and disease-specific survival, while the latter remained an independent factor by multivariate analysis. Reduced E-cadherin and β-catenin were both significantly associated with a poor overall survival and disease-specific survival by univariate and multivariate analyses. Conclusions: E-cadherin and β-catenin expression provides discriminative prognostic power independent of conventional pathologic factors, thus further reinforcing the important role of cell adhesion molecules in the process of tumor metastasis, especially in TNBC

Prognostic outcomes in advanced breast cancer: the metastasis-free interval is important

© 2017 Elsevier Inc. Metastatic breast cancer is a heterogeneous disease with a diverse clinical course. There have been limited studies regarding prognostic outcomes in patients with de novo metastatic breast cancer versus those with metastatic recurrence, with controversial observations. In this study, we sought to examine the difference in survival outcomes among patients with advanced breast cancer stratified based on metastasis-free interval (MFI) and to further explore the role of systemic therapy in these patient groups. Of 569 consecutive patients with stage IV breast cancer between 1998 and 2013, 201 had de novo metastatic disease (metastasis at diagnosis) and 368 developed metastatic recurrence, including 168 with an MFI ≤ 24 months and 200 with an MFI \u3e 24 months. In the 492 patients who received systemic therapy, de novo metastasis was an independent favorable prognostic factor for overall survival after metastasis when compared with metastatic recurrence irrespective of MFI. Compared with the patients with metastatic recurrence with an MFI ≤ 24 months, those with an MFI \u3e 24 months had a superior survival outcome, although it did not reach statistical significance by multivariate analysis. In contrast, de novo metastatic breast cancer was associated with a worse prognosis when compared with recurring metastasis in the patients who did not receive systemic treatment. These findings provide more insight into the natural history of advanced breast cancer, thus necessitating further investigation into the molecular mechanism of drug resistance

Effect of N on hot deformation behavior of high-Mn austenitic steel

The present study dealt with the hot compression deformation behavior of Fe−18.5Mn–7Cr−0.6C and Fe−18.5Mn–7Cr−0.6C−0.21 N high-Mn austenitic steels within a temperature range of 900–1200 °C, a strain rate range of 0.01–5 s−1, and a true strain of 0.7. The accurate constitutive equations were established according to their flow curves, and the deformation microstructures were also analyzed. The results revealed that the dominant softening mechanism for the two test steels without substantial peak stress (higher Zenger-Holloman parameter values) could also be dynamic recrystallization (DRX) rather than dynamic recovery (DRV). The addition of N enhanced the strain rate sensitivity of high-Mn austenitic steel at low temperatures and high strain rates. Furthermore, the addition of N increased the high temperature strength and hot deformation activation energy (Q) of high-Mn austenitic steel. Moreover, the addition of N could also increase the DRX volume fraction and refine the DRX grain size of high-Mn austenitic steel