Frontiers in Biology
Cover Story   2014, Volume 9 Issue 1
Mounting evidence points to critical roles for DNA modifications, including 5-methylcytosine (5mC) and its oxidized forms, in the development, plasticity and disorders of the mammalian nervous system. The novel DNA base 5-hydroxymethylcytosine (5hmC) is known to be capable of initiating passive or active DNA demethylation, but whether and how exten [Detail] ...
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, Volume 9 Issue 1

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MINI-REVIEW
Liposome mediated drug delivery for leukocyte adhesion deficieny I (LAD I): Targeting the mutated gene ITGB2 and expression of CD18 protein
C. Subathra DEVI, Kritika KEDARINATH, Payal CHOUDHARY, Vishakha TYAGI, Mohanasrinivasan. V
Front. Biol.. 2014, 9 (1): 1-4.  
https://doi.org/10.1007/s11515-013-1287-6

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Leukocyte adhesion deficiency (LAD) I is a disorder caused due to mutations in a gene (ITGB2) located on chromosome 21 and encodes the β2 subunit of the leukocyte integrin molecules. This leads to defects in the adhesion of leukocytes on endothelial cells which further leads to recurrent microbial infections due to a decrease in the immune response. Base Excision Repair Mechanism (BER) is instrumental in repairing damaged DNA by removing mutated/damaged bases. We have proposed a hypothesis for the treatment of LAD I by making use of the proteins/enzyme complexes responsible for base excision repair mechanism be introduced into the leukocytes via liposomes. This will target the mutated gene in the leukocytes (mostly neutrophils) and DNA repair will occur. The liposomes can be introduced into the patients via intravenous methods.

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REVIEW
Cytoskeletal changes in diseases of the nervous system
Alexandra K. SUCHOWERSKA,Thomas FATH
Front. Biol.. 2014, 9 (1): 5-17.  
https://doi.org/10.1007/s11515-014-1290-6

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The neuronal cytoskeleton not only provides the structural backbone of neurons, but also plays a fundamental role in maintaining neuronal functions. Dysregulation of neuronal architecture is evident in both injury and diseases of the central nervous system. These changes often result in the disruption of protein trafficking, loss of synapses and the death of neurons, ultimately impacting on signal transmission and manifesting in the disease phenotype. Furthermore, mutations in cytoskeletal proteins have been implicated in numerous diseases and, in some cases, identified as the cause of the disease, highlighting the critical role of the cytoskeleton in disease pathology. This review focuses on the role of cytoskeletal proteins in the pathology of mental disorders, neurodegenerative diseases and motor function deficits. In particular, we illustrate how cytoskeletal proteins can be directly linked to disease pathology and progression.

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Structural biology of the macroautophagy machinery
Leon H. CHEW,Calvin K. YIP
Front. Biol.. 2014, 9 (1): 18-34.  
https://doi.org/10.1007/s11515-014-1293-3

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Macroautophagy is a conserved degradative process mediated through formation of a unique double-membrane structure, the autophagosome. The discovery of autophagy-related (Atg) genes required for autophagosome formation has led to the characterization of approximately 20 genes mediating this process. Recent structural studies of the Atg proteins have provided the molecular basis for their function. Here we summarize the recent progress in elucidating the structural basis for autophagosome formation.

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Autophagy in cancer biology and therapy
Noor GAMMOH,Simon WILKINSON
Front. Biol.. 2014, 9 (1): 35-50.  
https://doi.org/10.1007/s11515-014-1294-2

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The role of macroautophagy (hereafter autophagy) in cancer biology and response to clinical intervention is complex. It is clear that autophagy is dysregulated in a wide variety of tumor settings, both during tumor initiation and progression, and in response to therapy. However, the pleiotropic mechanistic roles of autophagy in controlling cell behavior make it difficult to predict in a given tumor setting what the role of autophagy, and, by extension, the therapeutic outcome of targeting autophagy, might be. In this review we summarize the evidence in the literature supporting pro- and anti-tumorigenic and-therapeutic roles of autophagy in cancer. This overview encompasses roles of autophagy in nutrient management, cell death, cell senescence, regulation of proteotoxic stress and cellular homeostasis, regulation of tumor-host interactions and participation in changes in metabolism. We also try to understand, where possible, the mechanistic bases of these roles for autophagy. We specifically expand on the emerging role of genetically-engineered mouse models of cancer in shedding light on these issues in vivo. We also consider how any or all of the above functions of autophagy proteins might be targetable by extant or future classes of pharmacologic agents. We conclude by briefly exploring non-canonical roles for subsets of the key autophagy proteins in cellular processes, and how these might impact upon cancer.

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Gamma-glutamyl transferases: A structural, mechanistic and physiological perspective
Sharath BALAKRISHNA,Asmita A. PRABHUNE
Front. Biol.. 2014, 9 (1): 51-65.  
https://doi.org/10.1007/s11515-014-1288-0

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Gamma glutamyl transferases (GGT) are highly conserved enzymes that occur from bacteria to humans. They remove terminal γ-glutamyl residue from peptides and amides. GGTs play an important role in the homeostasis of glutathione (a major cellular antioxidant) and in the detoxification of xenobiotics in mammals. They are implicated in diseases like diabetes, inflammation, neurodegenerative diseases and cardiovascular diseases. The physiological role of GGTs in bacteria is still unclear. Nothing is known about the basis for the strong conservation of the enzyme across the living system. The review focuses on the enzyme’s physiology, chemistry and structural properties of the enzyme with emphasis on the evolutionary relationships. The available data indicate that the members of the GGT family share common structural features but are functionally heterogenous.

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RESEARCH ARTICLE
Genome-wide antagonism between 5-hydroxymethylcytosine and DNA methylation in the adult mouse brain
Junjie U. GUO,Keith E. SZULWACH,Yijing SU,Yujing LI,Bing YAO,Zihui XU,Joo Heon SHIN,Bing XIE,Yuan GAO,Guo-li MING,Peng JIN,Hongjun SONG
Front. Biol.. 2014, 9 (1): 66-74.  
https://doi.org/10.1007/s11515-014-1295-1

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Mounting evidence points to critical roles for DNA modifications, including 5-methylcytosine (5mC) and its oxidized forms, in the development, plasticity and disorders of the mammalian nervous system. The novel DNA base 5-hydroxymethylcytosine (5hmC) is known to be capable of initiating passive or active DNA demethylation, but whether and how extensively 5hmC functions in shaping the post-mitotic neuronal DNA methylome is unclear. Here we report the genome-wide distribution of 5hmC in dentate granule neurons from adult mouse hippocampus in vivo. 5hmC in the neuronal genome is highly enriched in gene bodies, especially in exons, and correlates with gene expression. Direct genome-wide comparison of 5hmC distribution between embryonic stem cells and neurons reveals extensive differences, reflecting the functional disparity between these two cell types. Importantly, integrative analysis of 5hmC, overall DNA methylation and gene expression profiles of dentate granule neurons in vivo reveals the genome-wide antagonism between these two states of cytosine modifications, supporting a role for 5hmC in shaping the neuronal DNA methylome by promoting active DNA demethylation.

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Amiloride and guggulsterone suppression of esophageal cancer cell growth in vitro and in nude mouse xenografts
Baoxiang GUAN,Ashraful HOQUE,Xiaochun XU
Front. Biol.. 2014, 9 (1): 75-81.  
https://doi.org/10.1007/s11515-014-1289-z

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Esophageal adenocarcinoma is increasing in the US and Western countries and frequent gastresophageal reflux or gastresophageal reflux disease carrying gastric acid and bile acid could contribute to esophageal adenocarcinogenesis. This study was designed to detect the expression of gastric acid-inducing gene Na+/H+ exchanger-1 (NHE-1) ex vivo and then to explore targeting of NHE-1 expression or activity to control esophageal cancer cell viability in vitro and in nude mouse xenografts. The data showed that NHE-1 was highly expressed in esophageal adenocarcinoma tissues (66 of 101 cases [65.3%], but not in normal esophageal squamous cell epithelium (1 of 26 cases [3.8%]). Knockdown of NHE-1 expression using NHE-1 shRNA or inhibition of NHE-1 activity using the NHE-1 inhibitor amiloride suppressed viability and induced apoptosis in esophageal cancer cells. Molecularly, amiloride inhibited expression of cyclooxygenase-2 and matrix metallopeptidase-9 but not NHE-1 mRNA in esophageal cancer cells. A combination of amiloride and guggulsterone (a natural bile acid receptor inhibitor) showed more than additive effects in suppressing esophageal cancer cell growth in vitro and in nude mouse xenografts. This study suggests that inhibition of NHE-1 expression or activity or combination of amiloride and guggulsterone could be useful in control of esophageal adenocarcinoma.

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Influence of ectomycorrhizal inoculation on Pinus wallichiana and Cedrus deodara seedlings under nursery conditions
Zahoor Ahmad ITOO,Zafar A. RESHI
Front. Biol.. 2014, 9 (1): 82-88.  
https://doi.org/10.1007/s11515-014-1292-4

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A study was undertaken to examine the extent of root colonization by four locally isolated ectomycorrhizal (ECM) fungi (Hebeloma theobrominum, Boletus dryophilus, Scleroderma citrinum and Suillus luteus) and their effects on seedling growth in Pinus wallichiana and Cedrus deodara under nursery conditions. Seedlings of the two conifers were inoculated with mycelium of ECM fungi and were grown in pots containing sterilized forest soil for six months. The percentage of ECM colonization of roots was 38%–52% in Pinus wallichiana and 33%–48% in Cedrus deodara. ECM colonization increased shoot height, needle number, shoot and root biomass and survival of inoculated seedlings. Among the four ECM fungi Hebeloma theobrominum was more effective with Pinus wallichiana and Scleroderma citrinum with Cedrus deodara in promoting seedling survival and overall growth. All the four ECM fungi used enhanced growth of inoculated seedlings and thus can be used in afforestation and regeneration programmes in degraded forests ecosystems.

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8 articles