Translation factor mRNA granules direct protein synthetic capacity to regions of polarized growth
mRNA localization serves key functions in localized protein production, making it critical that the translation machinery itself is present at these locations. Here we show that translation factor mRNAs are localized to distinct granules within yeast cells. In contrast to many messenger RNP granules, such as processing bodies and stress granules, which contain translationally repressed mRNAs, these granules harbor translated mRNAs under active growth conditions. The granules require Pab1p for their integrity and are inherited by developing daughter cells in a She2p/She3p-dependent manner. These results point to a model whe...
Source: Journal of Cell Biology - May 5, 2019 Category: Cytology Authors: Pizzinga, M., Bates, C., Lui, J., Forte, G., Morales-Polanco, F., Linney, E., Knotkova, B., Wilson, B., Solari, C. A., Berchowitz, L. E., Portela, P., Ashe, M. P. Tags: RNA Biology, Genetics Articles Source Type: research
Cyclin B3 is required for metaphase to anaphase transition in oocyte meiosis I
In this study, we explored the role of cyclin B3 in female meiosis by generating Ccnb3 mutant mice via CRISPR/Cas9. Ccnb3 mutant oocytes characteristically arrested at metaphase I (MetI) with normal spindle assembly and lacked enough anaphase-promoting complex/cyclosome (APC/C) activity, which is spindle assembly checkpoint (SAC) independent, to initiate anaphase I (AnaI). Securin siRNA or CDK1 inhibitor supplements rescued the MetI arrest. Furthermore, CCNB3 directly interacts with CDK1 to exert kinase function. Besides, the MetI arrest oocytes had normal development after intracytoplasmic sperm injection (ICSI) or parthe...
Source: Journal of Cell Biology - May 5, 2019 Category: Cytology Authors: Li, Y., Wang, L., Zhang, L., He, Z., Feng, G., Sun, H., Wang, J., Li, Z., Liu, C., Han, J., Mao, J., Li, P., Yuan, X., Jiang, L., Zhang, Y., Zhou, Q., Li, W. Tags: Cell Cycle and Division, Development Articles Source Type: research
Live imaging of marked chromosome regions reveals their dynamic resolution and compaction in mitosis
When human cells enter mitosis, chromosomes undergo substantial changes in their organization to resolve sister chromatids and compact chromosomes. To comprehend the timing and coordination of these events, we need to evaluate the progression of both sister chromatid resolution and chromosome compaction in one assay. Here we achieved this by analyzing changes in configuration of marked chromosome regions over time, with high spatial and temporal resolution. This assay showed that sister chromatids cycle between nonresolved and partially resolved states with an interval of a few minutes during G2 phase before completing ful...
Source: Journal of Cell Biology - May 5, 2019 Category: Cytology Authors: Eykelenboom, J. K., Gierlinski, M., Yue, Z., Hegarat, N., Pollard, H., Fukagawa, T., Hochegger, H., Tanaka, T. U. Tags: Cell Cycle and Division, DNA Biology Articles Source Type: research
Single nucleosome imaging reveals loose genome chromatin networks via active RNA polymerase II
Although chromatin organization and dynamics play a critical role in gene transcription, how they interplay remains unclear. To approach this issue, we investigated genome-wide chromatin behavior under various transcriptional conditions in living human cells using single-nucleosome imaging. While transcription by RNA polymerase II (RNAPII) is generally thought to need more open and dynamic chromatin, surprisingly, we found that active RNAPII globally constrains chromatin movements. RNAPII inhibition or its rapid depletion released the chromatin constraints and increased chromatin dynamics. Perturbation experiments of P-TEF...
Source: Journal of Cell Biology - May 5, 2019 Category: Cytology Authors: Nagashima, R., Hibino, K., Ashwin, S. S., Babokhov, M., Fujishiro, S., Imai, R., Nozaki, T., Tamura, S., Tani, T., Kimura, H., Shribak, M., Kanemaki, M. T., Sasai, M., Maeshima, K. Tags: Chromatin or Epigenetics, DNA Biology, Biophysics Articles Source Type: research
COPII vesicles contribute to autophagosomal membranes
This study provides a definitive answer to a long-standing, fundamental question regarding the mechanisms of autophagosome formation by implicating COPII vesicles as a membrane source for autophagosomes. (Source: Journal of Cell Biology)
Source: Journal of Cell Biology - May 5, 2019 Category: Cytology Authors: Shima, T., Kirisako, H., Nakatogawa, H. Tags: Cell Death and Autophagy Reports Source Type: research
Extramitochondrial cardiolipin suggests a novel function of mitochondria in spermatogenesis
Mitochondria contain cardiolipin (CL), an organelle-specific phospholipid that carries four fatty acids with a strong preference for unsaturated chains. Unsaturation is essential for the stability and for the function of mitochondrial CL. Surprisingly, we found tetrapalmitoyl-CL (TPCL), a fully saturated species, in the testes of humans and mice. TPCL was absent from other mouse tissues but was the most abundant CL species in testicular germ cells. Most intriguingly, TPCL was not localized in mitochondria but was in other cellular membranes even though mitochondrial CL was the substrate from which TPCL was synthesized. Dur...
Source: Journal of Cell Biology - May 5, 2019 Category: Cytology Authors: Ren, M., Xu, Y., Erdjument-Bromage, H., Donelian, A., Phoon, C. K. L., Terada, N., Strathdee, D., Neubert, T. A., Schlame, M. Tags: Membrane and Lipid Biology, Development Reports Source Type: research
Yeast centrosome components form a noncanonical LINC complex at the nuclear envelope insertion site
Bipolar spindle formation in yeast requires insertion of centrosomes (known as spindle pole bodies [SPBs]) into fenestrated regions of the nuclear envelope (NE). Using structured illumination microscopy and bimolecular fluorescence complementation, we map protein distribution at SPB fenestrae and interrogate protein–protein interactions with high spatial resolution. We find that the Sad1-UNC-84 (SUN) protein Mps3 forms a ring-like structure around the SPB, similar to toroids seen for components of the SPB insertion network (SPIN). Mps3 and the SPIN component Mps2 (a Klarsicht-ANC-1-Syne-1 domain [KASH]–like pro...
Source: Journal of Cell Biology - May 5, 2019 Category: Cytology Authors: Chen, J., Gardner, J. M., Yu, Z., Smith, S. E., McKinney, S., Slaughter, B. D., Unruh, J. R., Jaspersen, S. L. Tags: Cytoskeleton, Genetics Reports Source Type: research
Cell cycle- and genomic distance-dependent dynamics of a discrete chromosomal region
In contrast to the well-studied condensation and folding of chromosomes during mitosis, their dynamics during interphase are less understood. We deployed a CRISPR-based DNA imaging system to track the dynamics of genomic loci situated kilobases to megabases apart on a single chromosome. Two distinct modes of dynamics were resolved: local movements as well as ones that might reflect translational movements of the entire domain within the nucleoplasmic space. The magnitude of both of these modes of movements increased from early to late G1, whereas the translational movements were reduced in early S phase. The local fluctuat...
Source: Journal of Cell Biology - May 5, 2019 Category: Cytology Authors: Ma, H., Tu, L.-C., Chung, Y.-C., Naseri, A., Grunwald, D., Zhang, S., Pederson, T. Tags: Chromatin or Epigenetics, DNA Biology, Biophysics Reports Source Type: research
Reproducibility: Designing a rigorous microscopy experiment: Validating methods and avoiding bias
Images generated by a microscope are never a perfect representation of the biological specimen. Microscopes and specimen preparation methods are prone to error and can impart images with unintended attributes that might be misconstrued as belonging to the biological specimen. In addition, our brains are wired to quickly interpret what we see, and with an unconscious bias toward that which makes the most sense to us based on our current understanding. Unaddressed errors in microscopy images combined with the bias we bring to visual interpretation of images can lead to false conclusions and irreproducible imaging data. Here ...
Source: Journal of Cell Biology - May 5, 2019 Category: Cytology Authors: Jost, A. P.-T., Waters, J. C. Tags: Reproducibility Review Source Type: research
How cells fuse
Cell–cell fusion remains the least understood type of membrane fusion process. However, the last few years have brought about major advances in understanding fusion between gametes, myoblasts, macrophages, trophoblasts, epithelial, cancer, and other cells in normal development and in diseases. While different cell fusion processes appear to proceed via similar membrane rearrangements, proteins that have been identified as necessary and sufficient for cell fusion (fusogens) use diverse mechanisms. Some fusions are controlled by a single fusogen; other fusions depend on several proteins that either work together throug...
Source: Journal of Cell Biology - May 5, 2019 Category: Cytology Authors: Brukman, N. G., Uygur, B., Podbilewicz, B., Chernomordik, L. V. Tags: Membrane and Lipid Biology, Development Review Source Type: research
Neurons regulate synaptic strength through homeostatic scaling of active zones
How neurons stabilize their overall synaptic strength following conditions that alter synaptic morphology or function is a key question in neuronal homeostasis. In this issue, Goel et al. (2019. J. Cell Biol. https://doi.org/10.1083/jcb.201807165) find that neurons stabilize synaptic output despite disruptions in synapse size, active zone number, or postsynaptic function by controlling the delivery of active zone material and active zone size. (Source: Journal of Cell Biology)
Source: Journal of Cell Biology - May 5, 2019 Category: Cytology Authors: Cunningham, K. L., Littleton, J. T. Tags: Trafficking, Neuroscience Spotlight Source Type: research
ATG9 raises the BAR for PI4P in autophagy
ATG9 vesicles are crucial for autophagy, yet the role of ATG9 remains unclear. In this issue, Judith et al. (2019. J. Cell Biol. https://doi.org/10.1083/jcb.201901115) implicate the BAR protein Arfaptin2 in the loading of PI4-kinase IIIβ onto ATG9 vesicles for recruitment of ATG13 to the site of autophagosome biogenesis. (Source: Journal of Cell Biology)
Source: Journal of Cell Biology - May 5, 2019 Category: Cytology Authors: Shatz, O., Elazar, Z. Tags: Spotlight Source Type: research
A CRACker of an adaptor connects dynein-mediated transport to calcium signaling
Many different adaptor proteins activate the processivity of dynein–dynactin complexes and determine the specific cargo for retrograde transport by binding cargo receptors such as Rab GTP-binding (G) proteins. In this issue, Wang et al. (2019. J. Cell Biol. https://doi.org/10.1083/jcb.201806097) identify two GTPases that can function directly as dynein adaptors during endocytosis and are regulated by calcium. (Source: Journal of Cell Biology)
Source: Journal of Cell Biology - May 5, 2019 Category: Cytology Authors: Sharma, M., Dwivedi, D. Tags: Spotlight Source Type: research
Active RNA polymerase II curbs chromatin movement
Chromosomes are not very mobile during interphase. In this issue, Nagashima et al. (2019. J. Cell Biol. https://doi.org/10.1083/jcb.201811090) propose that the overall stabilization of genome structure is achieved by loose connections between DNA regions brought about by transcriptionally active RNA polymerases. (Source: Journal of Cell Biology)
Source: Journal of Cell Biology - May 5, 2019 Category: Cytology Authors: Hochberg-Laufer, H., Shav-Tal, Y. Tags: Spotlight Source Type: research
Gabriel Muhire Gihana: A candle loses nothing by lighting other candles
Gihana investigates how cells coordinate their shape and polarity with chromosome segregation. (Source: Journal of Cell Biology)
Source: Journal of Cell Biology - May 5, 2019 Category: Cytology Authors: ODonnell, M. A. Tags: People & amp;amp; Ideas Source Type: research
