scholarly journals Effect of tea root-derived proanthocyanidin fractions on protection of dentin collagen

2019 ◽  
Vol 48 (5) ◽  
pp. 030006051989130
Author(s):  
Honglin Yang ◽  
Bingqing Xie ◽  
Yue Wang ◽  
Yayun Cui ◽  
Hui Yang ◽  
...  
Keyword(s):  
Ethyl Acetate ◽  
Butyl Alcohol ◽  
Degree Of Polymerization ◽  
Cross Linking ◽  
Protective Mechanisms ◽  
Dentin Collagen ◽  
And Function ◽  
High Degree ◽  
Collagen Cross Linking

Objectives Proanthocyanidins (PAs) have been widely used as effective agents for dentin collagen cross-linking to enhance the biomechanics and biostability of dentin in vitro. However, the effects and protective mechanisms of various tea root-derived PA components on dentin remain undefined. This study evaluated the effects of these tea root-derived PA components on dentin biomechanics and biostability. Methods In this study, ethyl acetate and n-butyl alcohol were used to extract PAs with different degrees of polymerization from tea roots; the effects of these PA extracts on dentin were evaluated. Results Dentin was treated with glutaraldehyde, ethyl acetate, n-butyl alcohol, or water. PAs with a high degree of polymerization, extracted using n-butyl alcohol, were able to more effectively improve dentin collagen cross-linking, increase resistance to bacterial collagenase digestion, and enhance dentin elasticity, relative to treatment with glutaraldehyde or PAs with a low degree of polymerization (extracted using ethyl acetate). Additionally, treatment with aqueous extract of tea roots was detrimental to dentin stability and function. Conclusions PAs with a high degree of polymerization were effective for dentin protection and restoration in vitro, suggesting clinical treatment potential for tea root-derived PAs.

scholarly journals The Effect of Oxidized Dopamine on the Structure and Molecular Chaperone Function of the Small Heat-Shock Proteins, αB-Crystallin and Hsp27

2021 ◽  
Vol 22 (7) ◽  
pp. 3700
Author(s):  
Junna Hayashi ◽  
Jennifer Ton ◽  
Sparsh Negi ◽  
Daniel E. K. M. Stephens ◽  
Dean L. Pountney ◽  
...  
Keyword(s):  
Heat Shock ◽  
Protein Aggregation ◽  
Molecular Chaperone ◽  
Cross Linking ◽  
Αb Crystallin ◽  
The Cross ◽  
Shock Proteins ◽  
And Function

Oxidation of the neurotransmitter, dopamine (DA), is a pathological hallmark of Parkinson’s disease (PD). Oxidized DA forms adducts with proteins which can alter their functionality. αB-crystallin and Hsp27 are intracellular, small heat-shock molecular chaperone proteins (sHsps) which form the first line of defense to prevent protein aggregation under conditions of cellular stress. In vitro, the effects of oxidized DA on the structure and function of αB-crystallin and Hsp27 were investigated. Oxidized DA promoted the cross-linking of αB-crystallin and Hsp27 to form well-defined dimer, trimer, tetramer, etc., species, as monitored by SDS-PAGE. Lysine residues were involved in the cross-links. The secondary structure of the sHsps was not altered significantly upon cross-linking with oxidized DA but their oligomeric size was increased. When modified with a molar equivalent of DA, sHsp chaperone functionality was largely retained in preventing both amorphous and amyloid fibrillar aggregation, including fibril formation of mutant (A53T) α-synuclein, a protein whose aggregation is associated with autosomal PD. In the main, higher levels of sHsp modification with DA led to a reduction in chaperone effectiveness. In vivo, DA is sequestered into acidic vesicles to prevent its oxidation and, intracellularly, oxidation is minimized by mM levels of the antioxidant, glutathione. In vitro, acidic pH and glutathione prevented the formation of oxidized DA-induced cross-linking of the sHsps. Oxidized DA-modified αB-crystallin and Hsp27 were not cytotoxic. In a cellular context, retention of significant chaperone functionality by mildly oxidized DA-modified sHsps would contribute to proteostasis by preventing protein aggregation (particularly of α-synuclein) that is associated with PD.

scholarly journals Metabolic endotoxemia promotes adipose dysfunction and inflammation in human obesity

2019 ◽  
Vol 316 (2) ◽  
pp. E319-E332 ◽  
Author(s):  
Mercedes Clemente-Postigo ◽  
Wilfredo Oliva-Olivera ◽  
Leticia Coin-Aragüez ◽  
Bruno Ramos-Molina ◽  
Rosa María Giraldez-Perez ◽  
...  
Keyword(s):  
Metabolic Diseases ◽  
In Vitro Assays ◽  
Low Grade ◽  
Human Obesity ◽  
Gene And Protein Expression ◽  
And Function ◽  
Adipose Dysfunction ◽  
High Degree ◽  
Metabolic Endotoxemia

Impaired adipose tissue (AT) lipid handling and inflammation is associated with obesity-related metabolic diseases. Circulating lipopolysaccharides (LPSs) from gut microbiota (metabolic endotoxemia), proposed as a triggering factor for the low-grade inflammation in obesity, might also be responsible for AT dysfunction. Nevertheless, this hypothesis has not been explored in human obesity. To analyze the relationship between metabolic endotoxemia and AT markers for lipogenesis, lipid handling, and inflammation in human obesity, 33 patients with obesity scheduled for surgery were recruited and classified according to their LPS levels. Visceral and subcutaneous AT gene and protein expression were analyzed and adipocyte and AT in vitro assays performed. Subjects with obesity with a high degree of metabolic endotoxemia had lower expression of key genes for AT function and lipogenesis ( SREBP1, FABP4, FASN, and LEP) but higher expression of inflammatory genes in visceral and subcutaneous AT than subjects with low LPS levels. In vitro experiments corroborated that LPS are responsible for adipocyte and AT inflammation and downregulation of PPARG, SCD, FABP4, and LEP expression and LEP secretion. Thus, metabolic endotoxemia influences AT physiology in human obesity by decreasing the expression of factors involved in AT lipid handling and function as well as by increasing inflammation.

scholarly journals Overexpression of cofilin stimulates bundling of actin filaments, membrane ruffling, and cell movement in Dictyostelium.

1996 ◽  
Vol 132 (3) ◽  
pp. 335-344 ◽  
Author(s):  
H Aizawa ◽  
K Sutoh ◽  
I Yahara
Keyword(s):  
Actin Filaments ◽  
Cell Movement ◽  
Structure And Function ◽  
Cross Linking ◽  
Low Molecular Weight ◽  
Filamentous Actin ◽  
Membrane Ruffling ◽  
And Function

Cofilin is a low molecular weight actin-modulating protein whose structure and function are conserved among eucaryotes. Cofilin exhibits in vitro both a monomeric actin-sequestering activity and a filamentous actin-severing activity. To investigate in vivo functions of cofilin, cofilin was overexpressed in Dictyostelium discoideum cells. An increase in the content of D. discoideum cofilin (d-cofilin) by sevenfold induced a co-overproduction of actin by threefold. In cells over-expressing d-cofilin, the amount of filamentous actin but not that of monomeric actin was increased. Overexpressed d-cofilin co-sedimented with actin filaments, suggesting that the sequestering activity of d-cofilin is weak in vivo. The overexpression of d-cofilin increased actin bundles just beneath ruffling membranes where d-cofilin was co-localized. The overexpression of d-cofilin also stimulated cell movement as well as membrane ruffling. We have demonstrated in vitro that d-cofilin transformed latticework of actin filaments cross-linked by alpha-actinin into bundles probably by severing the filaments. D. discoideum cofilin may sever actin filaments in vivo and induce bundling of the filaments in the presence of cross-linking proteins so as to generate contractile systems involved in membrane ruffling and cell movement.

Collagen cross-linking: Lysyl oxidase dependent synthesis of pyridinoline in vitro: Confirmation that pyridinoline is derived from collagen

1982 ◽  
Vol 108 (4) ◽  
pp. 1546-1550 ◽  
Author(s):  
Robert C. Siegel ◽  
Joseph C.C. Fu ◽  
Norihiko Uto ◽  
Kentaro Horiuchi ◽  
Daisaburo Fujimoto
Keyword(s):  
Lysyl Oxidase ◽  
Cross Linking ◽  
Collagen Cross Linking

scholarly journals Comparison of tyrosine kinase domain properties for the neurotrophin receptors TrkA and TrkB

2020 ◽  
Vol 477 (20) ◽  
pp. 4053-4070
Author(s):  
Stephen C. Artim ◽  
Anatoly Kiyatkin ◽  
Mark A. Lemmon
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Kinases ◽  
Catalytic Efficiency ◽  
Kinase Domain ◽  
Tyrosine Kinase Domain ◽  
Signaling Dynamics ◽  
Cellular Context ◽  
And Function ◽  
High Degree

The tropomyosin-related kinase (Trk) family consists of three receptor tyrosine kinases (RTKs) called TrkA, TrkB, and TrkC. These RTKs are regulated by the neurotrophins, a class of secreted growth factors responsible for the development and function of neurons. The Trks share a high degree of homology and utilize overlapping signaling pathways, yet their signaling is associated with starkly different outcomes in certain cancers. For example, in neuroblastoma, TrkA expression and signaling correlates with a favorable prognosis, whereas TrkB is associated with poor prognoses. To begin to understand how activation of the different Trks can lead to such distinct cellular outcomes, we investigated differences in kinase activity and duration of autophosphorylation for the TrkA and TrkB tyrosine kinase domains (TKDs). We find that the TrkA TKD has a catalytic efficiency that is ∼2-fold higher than that of TrkB, and becomes autophosphorylated in vitro more rapidly than the TrkB TKD. Studies with mutated TKD variants suggest that a crystallographic dimer seen in many TrkA (but not TrkB) TKD crystal structures, which involves the kinase-insert domain, may contribute to this enhanced TrkA autophosphorylation. Consistent with previous studies showing that cellular context determines whether TrkB signaling is sustained (promoting differentiation) or transient (promoting proliferation), we also find that TrkB signaling can be made more transient in PC12 cells by suppressing levels of p75NTR. Our findings shed new light on potential differences between TrkA and TrkB signaling, and suggest that subtle differences in signaling dynamics can lead to substantial shifts in the cellular outcome.

scholarly journals Efficacy of new natural biomodification agents from Anacardiaceae extracts on dentin collagen cross-linking

2017 ◽  
Vol 33 (10) ◽  
pp. 1103-1109 ◽  
Author(s):  
M.A. Moreira ◽  
N.O. Souza ◽  
R.S. Sousa ◽  
D.Q. Freitas ◽  
M.V. Lemos ◽  
...  
Keyword(s):  
Cross Linking ◽  
Dentin Collagen ◽  
Collagen Cross Linking

scholarly journals Interaction of Neuromelanin with Xenobiotics and Consequences for Neurodegeneration; Promising Experimental Models

Antioxidants ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 824
Author(s):  
Andrea Capucciati ◽  
Fabio A. Zucca ◽  
Enrico Monzani ◽  
Luigi Zecca ◽  
Luigi Casella ◽  
...  
Keyword(s):  
Animal Models ◽  
Neurodegenerative Diseases ◽  
Brain Aging ◽  
Experimental Models ◽  
Test Tube ◽  
Age Related ◽  
And Function ◽  
Endogenous Metabolites ◽  
High Degree

Neuromelanin (NM) accumulates in catecholamine long-lived brain neurons that are lost in neurodegenerative diseases. NM is a complex substance made of melanic, peptide and lipid components. NM formation is a natural protective process since toxic endogenous metabolites are removed during its formation and as it binds excess metals and xenobiotics. However, disturbances of NM synthesis and function could be toxic. Here, we review recent knowledge on NM formation, toxic mechanisms involving NM, go over NM binding substances and suggest experimental models that can help identifying xenobiotic modulators of NM formation or function. Given the high likelihood of a central NM role in age-related human neurodegenerative diseases such as Parkinson’s and Alzheimer’s, resembling such diseases using animal models that do not form NM to a high degree, e.g., mice or rats, may not be optimal. Rather, use of animal models (i.e., sheep and goats) that better resemble human brain aging in terms of NM formation, as well as using human NM forming stem cellbased in vitro (e.g., mid-brain organoids) models can be more suitable. Toxicants could also be identified during chemical synthesis of NM in the test tube.

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