Drosophila vitelline membrane assembly: A critical role for an evolutionarily conserved cysteine in the “VM domain” of sV23

We have previously shown that during early Caenorhabditis elegans embryogenesis PKC-3, a C. elegans atypical PKC (aPKC), plays critical roles in the establishment of cell polarity required for subsequent asymmetric cleavage by interacting with PAR-3 [Tabuse, Y., Y. Izumi, F. Piano, K.J. Kemphues, J. Miwa, and S. Ohno. 1998. Development (Camb.). 125:3607–3614]. Together with the fact that aPKC and a mammalian PAR-3 homologue, aPKC-specific interacting protein (ASIP), colocalize at the tight junctions of polarized epithelial cells (Izumi, Y., H. Hirose, Y. Tamai, S.-I. Hirai, Y. Nagashima, T. Fujimoto, Y. Tabuse, K.J. Kemphues, and S. Ohno. 1998. J. Cell Biol. 143:95–106), this suggests a ubiquitous role for aPKC in establishing cell polarity in multicellular organisms. Here, we show that the overexpression of a dominant-negative mutant of aPKC (aPKCkn) in MDCK II cells causes mislocalization of ASIP/PAR-3. Immunocytochemical analyses, as well as measurements of paracellular diffusion of ions or nonionic solutes, demonstrate that the biogenesis of the tight junction structure itself is severely affected in aPKCkn-expressing cells. Furthermore, these cells show increased interdomain diffusion of fluorescent lipid and disruption of the polarized distribution of Na+,K+-ATPase, suggesting that epithelial cell surface polarity is severely impaired in these cells. On the other hand, we also found that aPKC associates not only with ASIP/PAR-3, but also with a mammalian homologue of C. elegans PAR-6 (mPAR-6), and thereby mediates the formation of an aPKC-ASIP/PAR-3–PAR-6 ternary complex that localizes to the apical junctional region of MDCK cells. These results indicate that aPKC is involved in the evolutionarily conserved PAR protein complex, and plays critical roles in the development of the junctional structures and apico-basal polarization of mammalian epithelial cells.

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MicroRNAs in Cardiac Autophagy: Small Molecules and Big Role

Cells ◽

10.3390/cells7080104 ◽

2018 ◽

Vol 7 (8) ◽

pp. 104 ◽

Cited By ~ 22

Author(s):

Teng Sun ◽

Meng-Yang Li ◽

Pei-Feng Li ◽

Ji-Min Cao

Keyword(s):

Cardiac Fibrosis ◽

Heart Diseases ◽

Critical Role ◽

Transcriptional Gene Silencing ◽

Close Link ◽

Post Transcriptional Gene Silencing ◽

Evolutionarily Conserved ◽

Cardiac Disorders ◽

Cellular Components

Autophagy, which is an evolutionarily conserved process according to the lysosomal degradation of cellular components, plays a critical role in maintaining cell homeostasis. Autophagy and mitochondria autophagy (mitophagy) contribute to the preservation of cardiac homeostasis in physiological settings. However, impaired or excessive autophagy is related to a variety of diseases. Recently, a close link between autophagy and cardiac disorders, including myocardial infarction, cardiac hypertrophy, cardiomyopathy, cardiac fibrosis, and heart failure, has been demonstrated. MicroRNAs (miRNAs) are a class of small non-coding RNAs with a length of approximately 21–22 nucleotides (nt), which are distributed widely in viruses, plants, protists, and animals. They function in mediating the post-transcriptional gene silencing. A growing number of studies have demonstrated that miRNAs regulate cardiac autophagy by suppressing the expression of autophagy-related genes in a targeted manner, which are involved in the pathogenesis of heart diseases. This review summarizes the role of microRNAs in cardiac autophagy and related cardiac disorders. Furthermore, we mainly focused on the autophagy regulation pathways, which consisted of miRNAs and their targeted genes.

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Cul4-Ddb1 ubiquitin ligases facilitate DNA replication-coupled sister chromatid cohesion through regulation of cohesin acetyltransferase Esco2

10.1101/414888 ◽

2018 ◽

Cited By ~ 1

Author(s):

Haitao Sun ◽

Jiaxin Zhang ◽

Jingjing Zhang ◽

Zhen Li ◽

Qinhong Cao ◽

...

Keyword(s):

Dna Replication ◽

Ubiquitin Ligase ◽

Sister Chromatid ◽

Critical Role ◽

E3 Ubiquitin Ligase ◽

Ubiquitin Ligases ◽

Sister Chromatid Cohesion ◽

Vital Role ◽

Chromatid Cohesion ◽

Evolutionarily Conserved

AbstractCohesin acetyltransferases Esco1 and Esco2 play a vital role in establishing sister chromatid cohesion. How Esco1 and Esco2 are controlled to achieve this in a DNA replication-coupled manner remains unclear in higher eukaryotes. Here we show that Cul4-RING ligases (CRL4s) play a critical role in sister chromatid cohesion in human cells. Depletion of Cul4A, Cul4B or Ddb1 subunits substantially reduces normal cohesion efficiency. We also show that Mms22L, a vertebrate ortholog of yeast Mms22, is one of Ddb1 and Cul4-associated factors (DCAFs) involved in cohesion. Several lines of evidence suggest a selective interaction of CRL4s with Esco2, but not Esco1. Depletion of either CRL4s or Esco2 causes a defect in Smc3 acetylation which can be rescued by HDAC8 inhibition. More importantly, both CRL4s and PCNA act as mediators for efficiently stabilizing Esco2 on chromatin and catalyzing Smc3 acetylation. Taken together, we propose an evolutionarily conserved mechanism in which CRL4s and PCNA regulate Esco2-dependent establishment of sister chromatid cohesion.Author summaryWe identified human Mms22L as a substrate specific adaptor of Cul4-Ddb1 E3 ubiquitin ligase. Downregulation of Cul4A, Cul4B or Ddb1 subunit causes reduction of acetylated Smc3, via interaction with Esco2 acetyltransferase, and then impairs sister chromatid cohesion in 293T cells. We found functional complementation between Cul4-Ddb1-Mms22L E3 ligase and Esco2 in Smc3 acetylation and sister chromatid cohesion. Interestingly, both Cul4-Ddb1 E3 ubiquitin ligase and PCNA contribute to Esco2 mediated Smc3 acetylation. To summarise, we demonstrated an evolutionarily conserved mechanism in which Cul4-Ddb1 E3 ubiquitin ligases and PCNA regulate Esco2-dependent establishment of sister chromatid cohesion.

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Viral strategies of manipulating autophagy to benefit infection

10.20944/preprints201905.0126.v1 ◽

2019 ◽

Author(s):

Ho Him Wong ◽

Sumana Sanyal

Keyword(s):

Rna Virus ◽

Critical Role ◽

Intracellular Pathogens ◽

Virus Infections ◽

Central Process ◽

Conservation Of Energy ◽

Evolutionarily Conserved ◽

Cellular Defence ◽

Host Metabolism ◽

Fine Tune

Autophagy is an evolutionarily conserved central process in host metabolism. Among its major functions are conservation of energy during starvation, recycling organelles, and turnover of long-lived proteins. Besides, autophagy plays a critical role in removing intracellular pathogens and very likely represents a primordial intrinsic cellular defence mechanism. More recent findings indicate that it has not only retained its ability to degrade intracellular pathogens, but also functions to augment and fine tune antiviral immune responses. Interestingly, viruses have also co-evolved strategies to manipulate this pathway and use it to their advantage. Particularly intriguing is infection-dependent activation of autophagy with positive stranded (+)RNA virus infections, which benefit from the pathway without succumbing to lysosomal degradation. In this review we summarise recent data on viral manipulation of autophagy, with a particular emphasis on +RNA viruses and highlight key unanswered questions in the field that we believe merit further attention.

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Leader peptidase of Escherichia coli: critical role of a small domain in membrane assembly

Science ◽

10.1126/science.3544218 ◽

1987 ◽

Vol 235 (4790) ◽

pp. 783-787 ◽

Cited By ~ 50

Author(s):

R. Dalbey ◽

W Wickner

Keyword(s):

Escherichia Coli ◽

Critical Role ◽

Membrane Assembly ◽

Small Domain ◽

Leader Peptidase

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Autophagy Defects in Skeletal Myopathies

Annual Review of Pathology Mechanisms of Disease ◽

10.1146/annurev-pathmechdis-012419-032618 ◽

2020 ◽

Vol 15 (1) ◽

pp. 261-285 ◽

Cited By ~ 6

Author(s):

Marta Margeta

Keyword(s):

Clinical Presentation ◽

Critical Role ◽

Lysosomal Degradation ◽

Cellular Mechanisms ◽

Biological Stress ◽

Evolutionarily Conserved ◽

Different Types ◽

Muscle Homeostasis ◽

Catabolic Process ◽

Cellular Organelles

Autophagy is an evolutionarily conserved catabolic process that targets different types of cytoplasmic cargo (such as bulk cytoplasm, damaged cellular organelles, and misfolded protein aggregates) for lysosomal degradation. Autophagy is activated in response to biological stress and also plays a critical role in the maintenance of normal cellular homeostasis; the latter function is particularly important for the integrity of postmitotic, metabolically active tissues, such as skeletal muscle. Through impairment of muscle homeostasis, autophagy dysfunction contributes to the pathogenesis of many different skeletal myopathies; the observed autophagy defects differ from disease to disease but have been shown to involve all steps of the autophagic cascade (from induction to lysosomal cargo degradation) and to impair both bulk and selective autophagy. To highlight the molecular and cellular mechanisms that are shared among different myopathies with deficient autophagy, these disorders are discussed based on the nature of the underlying autophagic defect rather than etiology or clinical presentation.

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Caenorhabditis elegans DYF-2, an Orthologue of Human WDR19, Is a Component of the Intraflagellar Transport Machinery in Sensory Cilia

Molecular Biology of the Cell ◽

10.1091/mbc.e06-04-0260 ◽

2006 ◽

Vol 17 (11) ◽

pp. 4801-4811 ◽

Cited By ~ 46

Author(s):

Evgeni Efimenko ◽

Oliver E. Blacque ◽

Guangshuo Ou ◽

Courtney J. Haycraft ◽

Bradley K. Yoder ◽

...

Keyword(s):

Caenorhabditis Elegans ◽

Aspartic Acid ◽

Critical Role ◽

Intraflagellar Transport ◽

Bardet Biedl Syndrome ◽

Evolutionarily Conserved ◽

Sensory Cilia ◽

Mutant Phenotypes ◽

And Function

The intraflagellar transport (IFT) machinery required to build functional cilia consists of a multisubunit complex whose molecular composition, organization, and function are poorly understood. Here, we describe a novel tryptophan-aspartic acid (WD) repeat (WDR) containing IFT protein from Caenorhabditis elegans, DYF-2, that plays a critical role in maintaining the structural and functional integrity of the IFT machinery. We determined the identity of the dyf-2 gene by transgenic rescue of mutant phenotypes and by sequencing of mutant alleles. Loss of DYF-2 function selectively affects the assembly and motility of different IFT components and leads to defects in cilia structure and chemosensation in the nematode. Based on these observations, and the analysis of DYF-2 movement in a Bardet–Biedl syndrome mutant with partially disrupted IFT particles, we conclude that DYF-2 can associate with IFT particle complex B. At the same time, mutations in dyf-2 can interfere with the function of complex A components, suggesting an important role of this protein in the assembly of the IFT particle as a whole. Importantly, the mouse orthologue of DYF-2, WDR19, also localizes to cilia, pointing to an important evolutionarily conserved role for this WDR protein in cilia development and function.

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Structural basis of Atg conjugation systems essential for autophagy

Acta Crystallographica Section A Foundations and Advances ◽

10.1107/s2053273314096971 ◽

2014 ◽

Vol 70 (a1) ◽

pp. C302-C302

Author(s):

Nobuo Noda

Keyword(s):

Molecular Mechanisms ◽

Critical Role ◽

Amide Bond ◽

Structural Basis ◽

Autophagosome Formation ◽

X Ray Crystallography ◽

Intracellular Degradation ◽

Atg Proteins ◽

Evolutionarily Conserved ◽

Biochemical Analyses

Autophagy is an evolutionarily-conserved, intracellular degradation system for which two ubiquitin-like modifiers, Atg8 and Atg12, play essential roles. After processed by Atg4, the exposed C-terminal glycine of Atg8 is activated by Atg7 (E1) and is then transferred to Atg3 (E2), and is finally conjugated with a phospholipid, phosphatidylethanolamine (PE) through an amide bond. Whereas, Atg12 is activated by the same E1, Atg7, without processing, and is then transferred to Atg10 (E2), and is finally conjugated with Atg5 through an isopeptide bond. Atg12-Atg5 conjugates, together with Atg16, function as an E3-like enzyme to facilitate the conjugation reaction between Atg8 and PE. During autophagy, Atg8-PE conjugates play a critical role in selective cargo recognition in addition to autophagosome formation. We determined the structures of all these Atg proteins and their complexes mainly by X-ray crystallography, and performed structure-based biochemical analyses on them [1,2]. These studies established the molecular mechanisms of Atg8 and Atg12 modification reactions that have many unique features compared with canonical ubiquitin-like systems. Furthermore, we found a conserved motif named the Atg8-family interacting motif (AIM), through which Atg8 recognizes specific cargoes and selectively incorporates them into autophagosomes for degradation [3].

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Cloning, expression, purification and crystallographic studies of galectin-11 from domestic sheep (Ovis aries)

Acta Crystallographica Section F Structural Biology Communications ◽

10.1107/s2053230x15010195 ◽

2015 ◽

Vol 71 (8) ◽

pp. 993-997 ◽

Cited By ~ 5

Author(s):

Dhanasekaran Sakthivel ◽

Dene Littler ◽

Adam Shahine ◽

Sally Troy ◽

Matthew Johnson ◽

...

Keyword(s):

Structural Information ◽

Critical Role ◽

Biological Significance ◽

Innate Immune ◽

Ovis Aries ◽

Domestic Sheep ◽

Innate Immune Responses ◽

Cellular Effects ◽

Evolutionarily Conserved ◽

Functional Mechanisms

Galectins are an evolutionarily conserved family of proteins that translate glycan recognition into cellular effects. Galectin-11 is a unique member of the galectin family that is only expressed in ruminants such as sheep, goat and cattle and that plays a critical role in several important biological processes, such as reproduction and parasite-mediated innate immune responses. Currently, these two areas are of major importance for the sustainability of ruminant livestock production. Despite the emerging biological significance of galectin-11, no structural information is available. It is expected that structural studies will unravel the functional mechanisms of galectin-11 activity. Here, the expression, purification and crystallization of the ruminant-specific galectin-11 from domestic sheep and the collection of X-ray data to 2.0 Å resolution are reported.

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A Critical Role for the Evolutionarily Conserved Gonadotropin-Releasing Hormone II: Mediation of Energy Status and Female Sexual Behavior

Endocrinology ◽

10.1210/en.2004-0148 ◽

2004 ◽

Vol 145 (8) ◽

pp. 3639-3646 ◽

Cited By ~ 77

Author(s):

Alexander S. Kauffman ◽

Emilie F. Rissman

Keyword(s):

Sexual Behavior ◽

Mating Behavior ◽

Critical Role ◽

Gnrh Receptor ◽

Energy Status ◽

Intracerebroventricular Infusion ◽

Ovariectomized Mice ◽

Evolutionarily Conserved ◽

Ad Libitum ◽

Ad Libitum Feeding

Abstract GnRH is an evolutionarily conserved neuropeptide, of which there are multiple structural variants; the function of the most widespread variant, GnRH-II, remains undefined. GnRH-II may affect reproductive behavior; GnRH-II administration to female musk shrews reinstates mating behavior previously inhibited by food restriction. To determine whether this action of GnRH-II is universal, we conducted the following studies in mice. Ovariectomized mice were primed with estradiol benzoate and progesterone once a week and tested for sexual behavior. Females showing a lordosis quotient (LQ) of 50 or higher on the fourth trial underwent food deprivation (FD) for either 24 or 48 h before an additional behavior test. FD for 48 h significantly reduced LQ compared with ad libitum-fed females. Next, females were FD for 48 h or maintained on ad libitum feeding and retested for sexual behavior after an intracerebroventricular infusion of either GnRH-I, GnRH-II, or saline. GnRH-II, but not GnRH-I, significantly increased LQ in FD females compared with FD females treated with saline. Lordosis was unaffected by GnRH-II in females maintained on ad libitum feeding. To assess whether the GnRH-I receptor mediates GnRH-II’s behavioral effects, underfed females were pretreated with the type 1 GnRH receptor antagonist Antide and retested for sexual behavior. Antide pretreatment did not prevent GnRH-II from promoting mating behavior, suggesting that GnRH-II’s behavioral actions are mediated through the type 2 GnRH receptor. We speculate that GnRH-II acts via its own receptor as a regulatory signal in mammals to ensure that reproduction is synchronized with energetically favorable conditions.

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