scholarly journals Rer1p maintains ciliary length and signaling by regulating γ-secretase activity and Foxj1a levels

2013 ◽  
Vol 200 (6) ◽  
pp. 709-720 ◽  
Author(s):  
Nathalie Jurisch-Yaksi ◽  
Applonia J. Rose ◽  
Huiqi Lu ◽  
Tim Raemaekers ◽  
Sebastian Munck ◽  
...  
Keyword(s):  
Quality Control ◽  
Mammalian Cells ◽  
Hedgehog Signaling ◽  
Protein Quality ◽  
Structure And Function ◽  
Sensory Function ◽  
Secretase Activity ◽  
Cilia Formation ◽  
Left Right Asymmetry ◽  
And Function

Cilia project from the surface of most vertebrate cells and are important for several physiological and developmental processes. Ciliary defects are linked to a variety of human diseases, named ciliopathies, underscoring the importance of understanding signaling pathways involved in cilia formation and maintenance. In this paper, we identified Rer1p as the first endoplasmic reticulum/cis-Golgi–localized membrane protein involved in ciliogenesis. Rer1p, a protein quality control receptor, was highly expressed in zebrafish ciliated organs and regulated ciliary structure and function. Both in zebrafish and mammalian cells, loss of Rer1p resulted in the shortening of cilium and impairment of its motile or sensory function, which was reflected by hearing, vision, and left–right asymmetry defects as well as decreased Hedgehog signaling. We further demonstrate that Rer1p depletion reduced ciliary length and function by increasing γ-secretase complex assembly and activity and, consequently, enhancing Notch signaling as well as reducing Foxj1a expression.

Oxidative protein folding in the mammalian endoplasmic reticulum

2004 ◽  
Vol 32 (5) ◽  
pp. 655-658 ◽  
Author(s):  
C.E. Jessop ◽  
S. Chakravarthi ◽  
R.H. Watkins ◽  
N.J. Bulleid
Keyword(s):  
Endoplasmic Reticulum ◽  
Mammalian Cells ◽  
Redox State ◽  
Structure And Function ◽  
Reduced Form ◽  
Secretory Proteins ◽  
Oxidative Protein Folding ◽  
Disulphide Bonds ◽  
And Function ◽  
Substrate Proteins

Native disulphide bonds are essential for the structure and function of many membrane and secretory proteins. Disulphide bonds are formed, reduced and isomerized in the endoplasmic reticulum of mammalian cells by a family of oxidoreductases, which includes protein disulphide isomerase (PDI), ERp57, ERp72, P5 and PDIR. This review will discuss how these enzymes are maintained in either an oxidized redox state that allows them to form disulphide bonds in substrate proteins or a reduced form that allows them to perform isomerization and reduction reactions, how these opposing pathways may co-exist within the same compartment and why so many oxidoreductases exist when PDI alone can perform all three of these functions.

Abstract 85: The AAA-ATPase p97 is a Critical Regulator of Cardiac Homeostasis

2017 ◽  
Vol 121 (suppl_1) ◽  
Author(s):  
Matthew J Brody ◽  
Michelle A Sargent ◽  
Jeffery D Molkentin
Keyword(s):  
Quality Control ◽  
Protein Quality ◽  
Protein Complexes ◽  
Protein Quality Control ◽  
Ubiquitin Proteasome System ◽  
Cellular Protein ◽  
Dominant Negative ◽  
Aaa Atpase ◽  
And Function ◽  
Thrombospondin 4

p97 is a AAA-ATPase that plays critical roles in a myriad of cellular protein quality control processes, including the endoplasmic reticulum (ER)-associated degradation (ERAD) pathway that targets misfolded proteins in the ER for degradation in the cytosol by the ubiquitin proteasome system. Mutations in p97 cause a multisystem degenerative proteinopathy disorder called inclusion body myopathy with Paget disease of bone and frontotemporal dementia (IBMPFD) that includes pathologies of the nervous system, skeletal muscle, bone, and heart. Previous studies in the laboratory into the mechanisms whereby thrombospondin 4 has its cardioprotective effects and enhanced ERAD activity identified p97 as a direct interacting partner. This observation suggested that p97 itself could be an important cardioprotective effector by benefiting protein quality control in the heart. To address this hypothesis here we generated cardiac-specific transgenic mice overexpressing wildtype p97 or a p97 K524A mutant with deficient ATPase activity, the latter of which functioned as a dominant negative. Mice overexpressing wildtype p97 exhibit normal cardiac structure and function while mutant p97 overexpressing mice develop cardiomyopathy, upregulate several ERAD complex components, and have elevated levels of ubiquitinated proteins. Proteomics and immunoprecipitation assays identified overwhelming interactions between endogenous p97 and a number of interesting protein complexes that suggest unique functions for this protein in regulating protein quality control in the heart. The results and novel regulatory relationships will be presented, which suggests entirely unique pathways whereby p97 functions in the heart.

Expanding the genetic code of mammalian cells

2017 ◽  
Vol 45 (2) ◽  
pp. 555-562 ◽  
Author(s):  
James S. Italia ◽  
Yunan Zheng ◽  
Rachel E. Kelemen ◽  
Sarah B. Erickson ◽  
Partha S. Addy ◽  
...  
Keyword(s):  
Protein Structure ◽  
Amino Acid ◽  
Mammalian Cells ◽  
Living Cells ◽  
Structure And Function ◽  
Unnatural Amino Acid ◽  
Full Potential ◽  
Recent Developments ◽  
Small Footprint ◽  
And Function

In the last two decades, unnatural amino acid (UAA) mutagenesis has emerged as a powerful new method to probe and engineer protein structure and function. This technology enables precise incorporation of a rapidly expanding repertoire of UAAs into predefined sites of a target protein expressed in living cells. Owing to the small footprint of these genetically encoded UAAs and the large variety of enabling functionalities they offer, this technology has tremendous potential for deciphering the delicate and complex biology of the mammalian cells. Over the last few years, exciting progress has been made toward expanding the toolbox of genetically encoded UAAs in mammalian cells, improving the efficiency of their incorporation and developing innovative applications. Here, we provide our perspective on these recent developments and highlight the current challenges that must be overcome to realize the full potential of this technology.

scholarly journals A toolbox of nanobodies developed and validated for diverse neuroscience research applications

2019 ◽  
Author(s):  
Jie-Xian Dong ◽  
Yongam Lee ◽  
Michael Kirmiz ◽  
Stephanie Palacio ◽  
Camelia Dumitras ◽  
...  
Keyword(s):  
Biomedical Research ◽  
Mammalian Cells ◽  
Structure And Function ◽  
Mammalian Brain ◽  
Tissue Penetration ◽  
Brain Neurons ◽  
Neuroscience Research ◽  
Form Part ◽  
Specific Proteins ◽  
And Function

SUMMARYNanobodies (nAbs) are small, minimal antibodies that have distinct attributes that make them uniquely suited for certain biomedical research, diagnostic and therapeutic applications. Prominent uses include as intracellular antibodies or intrabodies to bind and deliver cargo to specific proteins and/or subcellular sites within cells, and as nanoscale immunolabels for enhanced tissue penetration and improved spatial imaging resolution. Here, we report the generation and validation of nAbs against a set of proteins prominently expressed at specific subcellular sites in brain neurons. We describe a novel hierarchical validation pipeline to systematically evaluate nAbs isolated by phage display for effective and specific use as intrabodies and immunolabels in mammalian cells including brain neurons. These nAbs form part of a robust toolbox for targeting proteins with distinct and highly spatially-restricted subcellular localization in mammalian brain neurons, allowing for visualization and/or modulation of structure and function at those sites.

scholarly journals Drosophila MICOS knockdown impairs mitochondrial structure and function and promotes mitophagy in muscle tissue

Biology Open ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. bio054262
Author(s):  
Li-jie Wang ◽  
Tian Hsu ◽  
Hsiang-ling Lin ◽  
Chi-yu Fu
Keyword(s):  
Muscle Tissue ◽  
Mammalian Cells ◽  
Structure And Function ◽  
Tissue Homeostasis ◽  
Mitochondrial Morphology ◽  
Mitochondrial Structure ◽  
And Function ◽  
Nucleoid Structure

ABSTRACTThe mitochondrial contact site and cristae organizing system (MICOS) is a multi-protein interaction hub that helps define mitochondrial ultrastructure. While the functional importance of MICOS is mostly characterized in yeast and mammalian cells in culture, the contributions of MICOS to tissue homeostasis in vivo remain further elucidation. In this study, we examined how knocking down expression of Drosophila MICOS genes affects mitochondrial function and muscle tissue homeostasis. We found that CG5903/MIC26-MIC27 colocalizes and functions with Mitofilin/MIC60 and QIL1/MIC13 as a Drosophila MICOS component; knocking down expression of any of these three genes predictably altered mitochondrial morphology, causing loss of cristae junctions, and disruption of cristae packing. Furthermore, the knockdown flies exhibited low mitochondrial membrane potential, fusion/fission imbalances, increased mitophagy, and limited cell death. Reductions in climbing ability indicated deficits in muscle function. Knocking down MICOS genes also caused reduced mtDNA content and fragmented mitochondrial nucleoid structure in Drosophila. Together, our data demonstrate an essential role of Drosophila MICOS in maintaining proper homeostasis of mitochondrial structure and function to promote the function of muscle tissue.

scholarly journals NRF2-dependent gene expression promotes ciliogenesis and Hedgehog signaling

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Ana Martin-Hurtado ◽  
Raquel Martin-Morales ◽  
Natalia Robledinos-Antón ◽  
Ruth Blanco ◽  
Ines Palacios-Blanco ◽  
...  
Keyword(s):  
Hedgehog Signaling ◽  
Primary Cilia ◽  
Embryonic Stem ◽  
Mtor Inhibitors ◽  
Gene Promoters ◽  
Protein Levels ◽  
Functional Connections ◽  
Differentiated Cells ◽  
Cilia Formation ◽  
And Function

Abstract The transcription factor NRF2 is a master regulator of cellular antioxidant and detoxification responses, but it also regulates other processes such as autophagy and pluripotency. In human embryonic stem cells (hESCs), NRF2 antagonizes neuroectoderm differentiation, which only occurs after NRF2 is repressed via a Primary Cilia-Autophagy-NRF2 (PAN) axis. However, the functional connections between NRF2 and primary cilia, microtubule-based plasma membrane protrusions that function as cellular antennae, remain poorly understood. For instance, nothing is known about whether NRF2 affects cilia, or whether cilia regulation of NRF2 extends beyond hESCs. Here, we show that NRF2 and primary cilia reciprocally regulate each other. First, we demonstrate that fibroblasts lacking primary cilia have higher NRF2 activity, which is rescued by autophagy-activating mTOR inhibitors, indicating that the PAN axis also operates in differentiated cells. Furthermore, NRF2 controls cilia formation and function. NRF2-null cells grow fewer and shorter cilia and display impaired Hedgehog signaling, a cilia-dependent pathway. These defects are not due to increased oxidative stress or ciliophagy, but rather to NRF2 promoting expression of multiple ciliogenic and Hedgehog pathway genes. Among these, we focused on GLI2 and GLI3, the transcription factors controlling Hh pathway output. Both their mRNA and protein levels are reduced in NRF2-null cells, consistent with their gene promoters containing consensus ARE sequences predicted to bind NRF2. Moreover, GLI2 and GLI3 fail to accumulate at the ciliary tip of NRF2-null cells upon Hh pathway activation. Given the importance of NRF2 and ciliary signaling in human disease, our data may have important biomedical implications.

Analysis of Adhesion Plaque Structure and Function in the Mechanism of Transformation by Rous Sarcoma Virus

1982 ◽  
Vol 40 ◽  
pp. 110-113
Author(s):  
L.R. Rohrschneider ◽  
M.J. Rosok ◽  
L.E. Gentry
Keyword(s):  
Rous Sarcoma Virus ◽  
Mammalian Cells ◽  
Neoplastic Transformation ◽  
Structure And Function ◽  
Excellent Opportunity ◽  
Cells In Culture ◽  
Rous Sarcoma ◽  
Sarcoma Virus ◽  
And Function ◽  
Adhesion Plaque

Rous sarcoma virus (RSV) was originally isolated from a fibrosarcoma of a chicken. This virus also will efficiently infect and transform all avian cells in culture as well as most mammalian cells. The mechanism of transformation by RSV is therefore universal and this system offers an excellent opportunity to investigate the mechanism of neoplastic transformation.

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