scholarly journals Insights into animal septins using recombinant human septin octamers with distinct SEPT9 isoforms

2021 ◽  
Author(s):  
Francois Iv ◽  
Carla Silva Martins ◽  
Gerard Castro-Linares ◽  
Cyntia Taveneau ◽  
Pascale Barbier ◽  
...  
Keyword(s):  
Biological Functions ◽  
Mammalian Development ◽  
Cross Link ◽  
Complex Interactions ◽  
Biophysical Studies ◽  
First Time ◽  
Established Role ◽  
Design Cell ◽  
In Cells

Septin GTP-binding proteins contribute essential biological functions that range from the establishment of cell polarity to animal tissue morphogenesis. Human septins in cells form hetero-octameric septin complexes containing the ubiquitously expressed SEPT9. Despite the established role of SEPT9 in mammalian development and human pathophysiology, biochemical and biophysical studies have relied on monomeric SEPT9 thus not recapitulating its native assembly into hetero-octameric complexes. We established a protocol that enabled the first-time isolation of recombinant human septin octamers containing distinct SEPT9 isoforms. A combination of biochemical and biophysical assays confirmed the octameric nature of the isolated complexes in solution. Reconstitution studies showed that octamers with either a long or a short SEPT9 isoform form filament assemblies, and can directly bind and cross-link actin filaments, raising the possibility that septin-decorated actin structures in cells reflect direct actin-septin interactions. Recombinant SEPT9-containing octamers will make it possible to design cell-free assays to dissect the complex interactions of septins with cell membranes and the actin/microtubule cytoskeleton.

scholarly journals Insights into animal septins using recombinant human septin octamers with distinct SEPT9 isoforms

2021 ◽  
Author(s):  
Francois Iv ◽  
Carla Silva Martins ◽  
Gerard Castro-Linares ◽  
Cyntia Taveneau ◽  
Pascale Barbier ◽  
...  
Keyword(s):  
Actin Filaments ◽  
Mammalian Development ◽  
Cross Link ◽  
Complex Interactions ◽  
Biophysical Studies ◽  
First Time ◽  
Established Role ◽  
Design Cell ◽  
In Cells

AbstractSeptin GTP-binding proteins contribute essential biological functions that range from the establishment of cell polarity to animal tissue morphogenesis. Human septins in cells form hetero-octameric septin complexes containing the ubiquitously expressed SEPT9. Despite the established role of SEPT9 in mammalian development and human pathophysiology, biochemical and biophysical studies have relied on monomeric SEPT9 thus not recapitulating its native assembly into hetero-octameric complexes. We established a protocol that enabled the first-time isolation of recombinant human septin octamers containing distinct SEPT9 isoforms. A combination of biochemical and biophysical assays confirmed the octameric nature of the isolated complexes in solution. Reconstitution studies showed that octamers with either a long or a short SEPT9 isoform form filament assemblies, and can directly bind and cross-link actin filaments, raising the possibility that septin-decorated actin structures in cells reflect direct actin-septin interactions. Recombinant SEPT9-containing octamers will make it possible to design cell-free assays to dissect the complex interactions of septins with cell membranes and the actin/microtubule cytoskeleton.SummaryHuman septins in cells form hetero-octameric complexes containing the ubiquitously expressed SEPT9. Iv et al. describe the first-time isolation of recombinant human septin octamers with distinct SEPT9 isoforms. Reconstitution studies show that octamers with either a long or a short SEPT9 isoform form higher-order filament assemblies and directly bind and cross-link actin filaments.

scholarly journals Candida albicans forms biofilms on the vaginal mucosa

Microbiology ◽  
2010 ◽  
Vol 156 (12) ◽  
pp. 3635-3644 ◽  
Author(s):  
M. M. Harriott ◽  
E. A. Lilly ◽  
T. E. Rodriguez ◽  
P. L. Fidel ◽  
M. C. Noverr
Keyword(s):  
Biofilm Formation ◽  
Ex Vivo ◽  
Microscopic Analysis ◽  
Vaginal Mucosa ◽  
First Time ◽  
Established Role ◽  
Type Strains

Current understanding of resistance and susceptibility to vulvovaginal candidiasis challenges existing paradigms of host defence against fungal infection. While abiotic biofilm formation has a clearly established role during systemic Candida infections, it is not known whether C. albicans forms biofilms on the vaginal mucosa and the possible role of biofilms in disease. In vivo and ex vivo murine vaginitis models were employed to examine biofilm formation by scanning electron and confocal microscopy. C. albicans strains included 3153A (lab strain), DAY185 (parental control strain), and mutants defective in morphogenesis and/or biofilm formation in vitro (efg1/efg1 and bcr1/bcr1). Both 3153A and DAY815 formed biofilms on the vaginal mucosa in vivo and ex vivo as indicated by high fungal burden and microscopic analysis demonstrating typical biofilm architecture and presence of extracellular matrix (ECM) co-localized with the presence of fungi. In contrast, efg1/efg1 and bcr1/bcr1 mutant strains exhibited weak or no biofilm formation/ECM production in both models compared to wild-type strains and complemented mutants despite comparable colonization levels. These data show for the first time that C. albicans forms biofilms in vivo on vaginal epithelium, and that in vivo biotic biofilm formation requires regulators of biofilm formation (BCR1) and morphogenesis (EFG1).

scholarly journals UNC-45A Weakens and Breaks MT Lattice Independent of its Effect on Non-Muscle Myosin II

2020 ◽  
Author(s):  
Juri Habicht ◽  
Ashley Mooneyham ◽  
Asumi Hoshino ◽  
Mihir Shetty ◽  
Xiaonan Zhang ◽  
...  
Keyword(s):  
Neurodegenerative Diseases ◽  
Myosin Ii ◽  
Human Diseases ◽  
Therapeutic Implications ◽  
Associated Functions ◽  
Muscle Myosin ◽  
First Time ◽  
In Cells

AbstractIn invertebrates, UNC-45 regulates myosin stability and functions. Vertebrates have two distinct isoforms of the protein: UNC-45B, expressed in muscle cells only and UNC-45A, expressed in all cells and implicated in regulating both Non-Muscle Myosin II (NMII)- and microtubule (MT)-associated functions. Here we show for the first time that: a) in vitro UNC-45A binds to the MT lattice and weakens its integrity leading to MT bending, breakage and depolymerization, b) in cells, UNC-45A overexpression causes loss of MT mass and increase in MT breakages, c) both in vitro and in cells, UNC-45A destabilizes MTs independent of its NMII C-terminal binding domain and destabilization occurs even in presence of the NMII inhibitor blebbistatin. These findings are consistent with a not mutually exclusive but rather dual role of UNC-45A in regulating NMII activity and MT stability.Because many human diseases, from cancer to neurodegenerative diseases, are caused by or associated with deregulation of MT stability our findings have profound implications in both, the biology of MTs as well as the biology of human diseases and possible therapeutic implications for their treatment.

scholarly journals The function of LncRNA-H19 in cardiac hypertrophy

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Wenhua Su ◽  
Qian Huo ◽  
Hao Wu ◽  
Lulin Wang ◽  
Xiaoxue Ding ◽  
...  
Keyword(s):  
Cardiac Hypertrophy ◽  
Adaptive Response ◽  
Molecular Mechanisms ◽  
Myocardial Hypertrophy ◽  
Noncoding Rnas ◽  
Biological Functions ◽  
Pathological Mechanism ◽  
First Time ◽  
Insight Into

AbstractCardiac hypertrophy, characterized by the enlargement of cardiomyocytes, is initially an adaptive response to physiological and pathological stimuli. Decompensated cardiac hypertrophy is related to fibrosis, inflammatory cytokine, maladaptive remodeling, and heart failure. Although pathological myocardial hypertrophy is the main cause of hypertrophy-related morbidity and mortality, our understanding of its mechanism is still poor. Long noncoding RNAs (lncRNAs) are noncoding RNAs that regulate various physiological and pathological processes through multiple molecular mechanisms. Recently, accumulating evidence has indicated that lncRNA-H19 is a potent regulator of the progression of cardiac hypertrophy. For the first time, this review summarizes the current studies about the role of lncRNA-H19 in cardiac hypertrophy, including its pathophysiological processes and underlying pathological mechanism, including calcium regulation, fibrosis, apoptosis, angiogenesis, inflammation, and methylation. The context within which lncRNA-H19 might be developed as a target for cardiac hypertrophy treatment is then discussed to gain better insight into the possible biological functions of lncRNA-H19 in cardiac hypertrophy.

scholarly journals The Double-Histone-Acetyltransferase Complex ATAC Is Essential for Mammalian Development

2008 ◽  
Vol 29 (5) ◽  
pp. 1176-1188 ◽  
Author(s):  
Sebastián Guelman ◽  
Kenji Kozuka ◽  
Yifan Mao ◽  
Victoria Pham ◽  
Mark J. Solloway ◽  
...  
Keyword(s):  
Cell Cycle Progression ◽  
Histone H4 ◽  
Mammalian Development ◽  
Histone Tails ◽  
Cycle Progression ◽  
Enzymatic Function ◽  
The Stability ◽  
First Time

ABSTRACT Acetylation of the histone tails, catalyzed by histone acetyltransferases (HATs), is a well-studied process that contributes to transcriptionally active chromatin states. Here we report the characterization of a novel mammalian HAT complex, which contains the two acetyltransferases GCN5 and ATAC2 as well as other proteins linked to chromatin metabolism. This multisubunit complex has a similar but distinct subunit composition to that of the Drosophila ADA2A-containing complex (ATAC). Recombinant ATAC2 has a weak HAT activity directed to histone H4. Moreover, depletion of ATAC2 results in the disassembly of the complex, indicating that ATAC2 not only carries out an enzymatic function but also plays an architectural role in the stability of mammalian ATAC. By targeted disruption of the Atac2 locus in mice, we demonstrate for the first time the essential role of the ATAC complex in mammalian development, histone acetylation, cell cycle progression, and prevention of apoptosis during embryogenesis.

scholarly journals TAp63α targeting of Lgr5 mediates colorectal cancer stem cell properties and sulforaphane inhibition

Oncogenesis ◽  
2020 ◽  
Vol 9 (10) ◽  
Author(s):  
Yue Chen ◽  
Meng-huan Wang ◽  
Jian-yun Zhu ◽  
Chun-feng Xie ◽  
Xiao-ting Li ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Stem Cell ◽  
Cancer Progression ◽  
Inhibitory Effect ◽  
P53 Family ◽  
First Time ◽  
Established Role

Abstract Cancer stem cells (CSCs) have an established role in cancer progression and therapeutic resistance. The p63 proteins are important transcription factors which belong to the p53 family, but their function and mechanism in CSCs remain elusive. Here, we investigated the role of TAp63α in colorectal CSCs and the effects of sulforaphane on TAp63α. We found that TAp63α was upregulated in spheres with stem cell properties compared to the parental cells. Overexpression of TAp63α promoted self-renewal capacity and enhanced CSC markers expression in colorectal sphere-forming cells. Furthermore, we showed that TAp63α directly bound to the promoter region of Lgr5 to enhance its expression and activate its downstream β-catenin pathway. Functional experiments revealed that sulforaphane suppressed the stemness of colorectal CSCs both in vitro and in vivo. Upregulation of TAp63α attenuated the inhibitory effect of sulforaphane on colorectal CSCs, indicating the role of TAp63α in sulforaphane suppression of the stemness in colorectal cancer. The present study elucidated for the first time that TAp63α promoted CSCs through targeting Lgr5/β-catenin axis and participated in sulforaphane inhibition of the stem cell properties in colorectal cancer.

scholarly journals FOXK2 Transcription Factor and Its Emerging Roles in Cancer

Cancers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 393 ◽  
Author(s):  
Gabriela Nestal de Moraes ◽  
Luciana Carneiro ◽  
Raquel Maia ◽  
Eric Lam ◽  
Andrew Sharrocks
Keyword(s):  
Prognostic Value ◽  
Large Family ◽  
Biological Processes ◽  
Biological Functions ◽  
Invasion And Metastasis ◽  
Complex Interactions ◽  
Forkhead Box ◽  
A Cell ◽  
And Function

Forkhead box (FOX) transcription factors compose a large family of regulators of key biological processes within a cell. FOXK2 is a member of FOX family, whose biological functions remain relatively unexplored, despite its description in the early nineties. More recently, growing evidence has been pointing towards a role of FOXK2 in cancer, which is likely to be context-dependent and tumour-specific. Here, we provide an overview of important aspects concerning the mechanisms of regulation of FOXK2 expression and function, as well as its complex interactions at the chromatin level, which orchestrate how it differentially regulates the expression of gene targets in pathophysiology. Particularly, we explore the emerging functions of FOXK2 as a regulator of a broad range of cancer features, such as cell proliferation and survival, DNA damage, metabolism, migration, invasion and metastasis. Finally, we discuss the prognostic value of assessing FOXK2 expression in cancer patients and how it can be potentially targeted for future anticancer interventions.

scholarly journals The Central Role of the Tail in Switching Off Myosin II in Cells

2019 ◽  
Author(s):  
Shixin Yang ◽  
Kyoung Hwan Lee ◽  
John L. Woodhead ◽  
Osamu Sato ◽  
Mitsuo Ikebe ◽  
...  
Keyword(s):  
Atp Hydrolysis ◽  
Myosin Ii ◽  
Actin Binding ◽  
Compact Structure ◽  
Mechanism Of Inhibition ◽  
Energy Conserving ◽  
High Degree ◽  
First Time ◽  
In Cells

AbstractMyosin II is a motor protein playing an essential role in cell motility. The molecule can exist as a polymer that pulls on actin to generate motion, or as an inactive monomer with a compact structure, in which its tail is folded and its two heads interact with each other. This conformation functions in cells as an energy-conserving storage and transport molecule. The mechanism of inhibition is not fully understood. We have carried out a 3D reconstruction of the switched-off form revealing for the first time multiple interactions between the tail and the two heads that trap ATP hydrolysis products, block actin binding, obstruct head phosphorylation, and prevent filament formation. Blocking these essential features of myosin function can explain the high degree of inhibition of the folded form of myosin, serving its energy-conserving, storage function in cells. The structure also suggests a mechanism for unfolding when activated by phosphorylation.

scholarly journals The Na+ Channel Inactivation Gate Is a Molecular Complex

2004 ◽  
Vol 123 (2) ◽  
pp. 155-165 ◽  
Author(s):  
Howard K. Motoike ◽  
Huajun Liu ◽  
Ian W. Glaaser ◽  
An-Suei Yang ◽  
Michihiro Tateyama ◽  
...  
Keyword(s):  
Molecular Complex ◽  
Na Channel ◽  
Α Subunit ◽  
Voltage Gated ◽  
Complex Interactions ◽  
Channel Inactivation ◽  
T Domain ◽  
First Time ◽  
Depolarization Inactivation

Electrical activity in nerve, skeletal muscle, and heart requires finely tuned activity of voltage-gated Na+ channels that open and then enter a nonconducting inactivated state upon depolarization. Inactivation occurs when the gate, the cytoplasmic loop linking domains III and IV of the α subunit, occludes the open pore. Subtle destabilization of inactivation by mutation is causally associated with diverse human disease. Here we show for the first time that the inactivation gate is a molecular complex consisting of the III-IV loop and the COOH terminus (C-T), which is necessary to stabilize the closed gate and minimize channel reopening. When this interaction is disrupted by mutation, inactivation is destabilized allowing a small, but important, fraction of channels to reopen, conduct inward current, and delay cellular repolarization. Thus, our results demonstrate for the first time that physiologically crucial stabilization of inactivation of the Na+ channel requires complex interactions of intracellular structures and indicate a novel structural role of the C-T domain in this process.

scholarly journals Thalamic state control of cortical paired-pulse dynamics

2017 ◽  
Vol 117 (1) ◽  
pp. 163-177 ◽  
Author(s):  
Clarissa J. Whitmire ◽  
Daniel C. Millard ◽  
Garrett B. Stanley
Keyword(s):  
Temporal Patterns ◽  
Sensory Stimulation ◽  
Complex Stimulus ◽  
State Control ◽  
Unit Recording ◽  
Complex Interactions ◽  
The Face ◽  
First Time

Sensory stimulation drives complex interactions across neural circuits as information is encoded and then transmitted from one brain region to the next. In the highly interconnected thalamocortical circuit, these complex interactions elicit repeatable neural dynamics in response to temporal patterns of stimuli that provide insight into the circuit properties that generated them. Here, using a combination of in vivo voltage-sensitive dye (VSD) imaging of cortex, single-unit recording in thalamus, and optogenetics to manipulate thalamic state in the rodent vibrissa pathway, we probed the thalamocortical circuit with simple temporal patterns of stimuli delivered either to the whiskers on the face (sensory stimulation) or to the thalamus directly via electrical or optogenetic inputs (artificial stimulation). VSD imaging of cortex in response to whisker stimulation revealed classical suppressive dynamics, while artificial stimulation of thalamus produced an additional facilitation dynamic in cortex not observed with sensory stimulation. Thalamic neurons showed enhanced bursting activity in response to artificial stimulation, suggesting that bursting dynamics may underlie the facilitation mechanism we observed in cortex. To test this experimentally, we directly depolarized the thalamus, using optogenetic modulation of the firing activity to shift from a burst to a tonic mode. In the optogenetically depolarized thalamic state, the cortical facilitation dynamic was completely abolished. Together, the results obtained here from simple probes suggest that thalamic state, and ultimately thalamic bursting, may play a key role in shaping more complex stimulus-evoked dynamics in the thalamocortical pathway. NEW & NOTEWORTHY For the first time, we have been able to utilize optogenetic modulation of thalamic firing modes combined with optical imaging of cortex in the rat vibrissa system to directly test the role of thalamic state in shaping cortical response properties.

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