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101.
Jennifer R. Shell David S. Lawrence 《Biochimica et Biophysica Acta - Proteins and Proteomics》2013,1834(7):1359-1363
The development of a fluorescent assay to detect activity of the mitochondrial cAMP-dependent protein kinase (PKA) is described. A peptide-based sensor was utilized to quantify the relative amount of PKA activity present in each compartment of the mitochondria (the outer membrane, the intermembrane space, and the matrix). In the process of validating this assay, we discovered that PKA activity is regulated by the protease calpain. Upon exposure of bovine heart mitochondria to digitonin, Ca2 +, and a variety of electron transport chain inhibitors, the regulatory subunits of the PKA holoenzyme (R2C2) are digested, releasing active catalytic subunits. This proteolysis is attenuated by calpain inhibitor I (ALLN). This article is part of a Special Issue entitled: Inhibitors of Protein Kinases (2012). 相似文献
102.
103.
104.
Ning Xu Gen-Yi Qu Yu-Peng Wu Yun-Zhi Lin Dong-Ning Chen Xiao-Dong Li Shao-Hao Chen Jin-Bei Huang Qing-Shui Zheng Xue-Yi Xue Yong Wei 《Journal of cellular biochemistry》2020,121(1):231-243
The significance of actin-related protein 2/3 complex subunit 4 (ARPC4) expression in bladder cancer, and its potential role in the invasion and migration of bladder cancer cells, has yet to be determined. This study was to identify the correlation between ARPC4 and lymph node metastasis, and to determine the role of ARPC4 in the invasive migration of T24 bladder cancer cells. One hundred and ninety-eight bladder cancer tissues and 40 normal bladder and lymph node tissues were examined. Tissue microarrays were constructed and subjected to immunohistochemical stating for ARPC4. Multiple logistic analysis was used to determine risk factors associated with bladder cancer metastasis. ARPC4 expression in T24 bladder cancer cells was suppressed using small interfering RNA and changes in protein levels were determined by Western blot analysis. The proliferation of bladder cancer cells after knocking down of ARPC4 was determined by cell counting kit-8. The effects of ARPC4 knockdown on T24 cell invasion and migration was determined using transwell and wound healing assays. Immunofluorescence analysis was performed to examine changes in pseudopodia formation and actin cytoskeleton structure. The expression of ARPC4 was elevated in bladder cancer tissues than normal tissues (84.3% vs 27.5%, P < 0.001). The multivariate logistic analysis demonstrated that the level of ARPC4, as a risk factor, was correlated with lymphatic metastasis (P < 0.05). ARPC4 knockdown attenuated proliferation, migration, invasion, and pseudopodia formation in T24 cells. ARPC4 expression, as a risk factor, is associated with lymphatic metastasis and is upregulated in bladder cancer tissues in comparison with normal tissues. Inhibition of ARPC4 expression significantly attenuates the proliferation, migration, and invasion of bladder cancer cell, possibly due to defects in pseudopodia formation. 相似文献
105.
Matthew R. Femia Rochelle M. Evans Jibo Zhang Xiaopeng Sun Caroline J. Lebegue Vincent R. Roggero Lizabeth A. Allison 《Journal of cellular biochemistry》2020,121(4):2909-2926
The thyroid hormone receptors (TRs) mediate thyroid hormone (T3)-dependent gene expression. The nuclear import and export signals that direct TR shuttling are well characterized, but little is known about factors modulating nuclear retention. We used fluorescence-based nucleocytoplasmic scoring and fluorescence recovery after photobleaching in transfected cells to investigate whether Mediator subunits MED1 and MED13 play a role in nuclear retention of TR. When MED1 was overexpressed, there was a striking shift towards a greater nuclear localization of TRβ1 and the oncoprotein v-ErbA, subtypes with cytosolic populations at steady-state, and TRβ1 intranuclear mobility was reduced. For TRα1, there was no observable change in its predominantly nuclear distribution pattern or mobility. Consistent with a role for MED1 in nuclear retention, the cytosolic TRα1 and TRβ1 population were significantly greater in MED1−/− cells, compared with MED1+/+ cells. Exposure to T3 and epidermal growth factor, which induces MED1 phosphorylation, also altered TR intranuclear dynamics. Overexpression of miR-208a, which downregulates MED13, led to a more cytosolic distribution of nuclear-localized TRα1; however, overexpression of MED13 had no effect on TRβ1 localization. The known binding site of MED1 overlaps with a transactivation domain and nuclear export signal in helix 12 of TR's ligand-binding domain (LBD). Coimmunoprecipitation assays demonstrated that TR's LBD interacts directly with exportins 5 and 7, suggesting that binding of exportins and MED1 to TR may be mutually exclusive. Collectively, our data provide evidence that MED1 promotes nuclear retention of TR, and highlight the dual functionality of helix 12 in TR transactivation and nuclear export. 相似文献
106.
Hsp16.3, a molecular chaperone, plays a vital role in the growth and survival of Mycobacterium tuberculosis inside the host. We previously reported that deletion of three amino acid residues (142STN144) from C-terminal extension (CTE) of Hsp16.3 triggers its structural perturbation and increases its chaperone activity, which reaches its apex upon the deletion of its entire CTE (141RSTN144). Thus, we hypothesized that Arg141 (R141) and Ser142 (S142) in the CTE of Hsp16.3 possibly hold the key in maintaining its native-like structure and chaperone activity. To test this hypothesis, we generated two deletion mutants in which R141 and S142 were deleted individually (Hsp16.3ΔR141 and Hsp16.3ΔS142) and three substitution mutants in which R141 was replaced by lysine (Hsp16.3R141K), alanine (Hsp16.3R141A), and glutamic acid (Hsp16.3R141E), respectively. Hsp16.3ΔS142 or Hsp16.3R141K mutant has native-like structure and chaperone activity. Deletion of R141 from the CTE (Hsp16.3ΔR141) perturbs the secondary and tertiary structure, lowers the subunit exchange dynamics and decreases the chaperone activity of Hsp16.3. But, the substitution of R141 with alanine (Hsp16.3R141A) or glutamic acid (Hsp16.3R141E) perturbs its secondary and tertiary structure. Surprisingly, such charge tampering of R141 enhances the subunit exchange dynamics and chaperone activity of Hsp16.3. Interestingly, neither the deletion of R141/S142 nor the substitution of R141 with lysine, alanine and glutamic acid affects the oligomeric mass/size of Hsp16.3. Overall, our study suggests that R141 (especially the positive charge on R141) plays a crucial role in maintaining the native-like structure as well as in regulating subunit exchange dynamics and chaperone activity of Hsp16.3. 相似文献
107.
Sylvain Hanein Mathilde Garcia Lucas Fares-Taie Valérie Serre Yves De Keyzer Thierry Delaveau Isabelle Perrault Nathalie Delphin Sylvie Gerber Alain Schmitt Jean-Marc Masse Arnold Munnich Josseline Kaplan Frédéric Devaux Jean-Michel Rozet 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013
Background
Hereditary optic neuropathies (HONs) are a heterogeneous group of disorders that affect retinal ganglion cells (RGCs) and axons that form the optic nerve. Leber's Hereditary Optic Neuropathy and the autosomal dominant optic atrophy related to OPA1 mutations are the most common forms. Nonsyndromic autosomal recessive optic neuropathies are rare and their existence has been long debated. We recently identified the first gene responsible for these conditions, TMEM126A. This gene is highly expressed in retinal cellular compartments enriched in mitochondria and supposed to encode a mitochondrial transmembrane protein of unknown function.Methods
A specific polyclonal antibody targeting the TMEM126A protein has been generated. Quantitative fluorescent in situ hybridization, cellular fractionation, mitochondrial membrane association study, mitochondrial sub compartmentalization analysis by both proteolysis assays and transmission electron microscopy, and expression analysis of truncated TMEM126A constructs by immunofluorescence confocal microscopy were carried out.Results
TMEM126A mRNAs are strongly enriched in the vicinity of mitochondria and encode an inner mitochondrial membrane associated cristae protein. Moreover, the second transmembrane domain of TMEM126A is required for its mitochondrial localization.Conclusions
TMEM126A is a mitochondrial located mRNA (MLR) that may be translated in the mitochondrial surface and the protein is subsequently imported to the inner membrane. These data constitute the first step toward a better understanding of the mechanism of action of TMEM126A in RGCs and support the importance of mitochondrial dysfunction in the pathogenesis of HON.General significance
Local translation of nuclearly encoded mitochondrial mRNAs might be a mechanism for rapid onsite supply of mitochondrial membrane proteins. 相似文献108.
Frederick J. Warren Peter J. ButterworthPeter R. Ellis 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013
Background
Starch is a main source of carbohydrate in human diets, but differences are observed in postprandial glycaemia following ingestion of different foods containing identical starch contents. Such differences reflect variations in rates at which different starches are digested in the intestine. In seeking explanations for these differences, we have studied the interaction of α-amylase with starch granules. Understanding this key step in digestion should help with a molecular understanding for observed differences in starch digestion rates.Methods
For enzymes acting upon solid substrates, a Freundlich equation relates reaction rate to enzyme adsorption at the surface. The Freundlich exponent (n) equals 2/3 for a liquid-smooth surface interface, 1/3 for adsorption to exposed edges of ordered structures and 1.0 for solution–solution interfaces. The topography of a number of different starch granules, revealed by Freundlich exponents, was compared with structural data obtained by differential scanning calorimetry and Fourier transform infrared spectroscopy with attenuated total internal reflectance (FTIR-ATR).Results
Enzyme binding rate and FTIR-ATR peak ratio were directly proportional to n and ΔgelH was inversely related to n. Amylase binds fastest to solubilised starch and to granules possessing smooth surfaces at the solid–liquid interface and slowest to granules possessing ordered crystalline surfaces.Conclusions
Freundlich exponents provide information about surface blocklet structures of starch that supplements knowledge obtained from physical methods.General Significance
Nanoscale structures at the surface of starch granules influence hydrolysis by α-amylase. This can be important in understanding how dietary starch is digested with relevance to diabetes, cardiovascular health and cancer. 相似文献109.
Gerda Neubert Katja von Au Katrin Drossel Andreas Tzschach Denise Horn Renate Nickel Angela M. Kaindl 《Gene》2013
Angelman syndrome is a neurodevelopmental disorder characterized by mental retardation, severe speech disorder, facial dysmorphism, secondary microcephaly, ataxia, seizures, and abnormal behaviors such as easily provoked laughter. It is most frequently caused by a de novo maternal deletion of chromosome 15q11–q13 (about 70–90%), but can also be caused by paternal uniparental disomy of chromosome 15q11–q13 (3–7%), an imprinting defect (2–4%) or in mutations in the ubiquitin protein ligase E3A gene UBE3A mostly leading to frame shift mutation. In addition, for patients with overlapping clinical features (Angelman-like syndrome), mutations in methyl-CpG binding protein 2 gene MECP2 and cyclin-dependent kinase-like 5 gene CDKL5 as well as a microdeletion of 2q23.1 including the methyl-CpG binding domain protein 5 gene MBD5 have been described. Here, we describe a patient who carries a de novo 5 Mb-deletion of chromosome 15q11.2–q13.1 known to be associated with Angelman syndrome and a further, maternally inherited deletion 2q21.3 (~ 364 kb) of unknown significance. In addition to classic features of Angelman syndrome, she presented with severe infections in the first year of life, a symptom that has not been described in patients with Angelman syndrome. The 15q11.2–q13.1 deletion contains genes critical for Prader–Willi syndrome, the Angelman syndrome causing genes UBE3A and ATP10A/C, and several non-imprinted genes: GABRB3 and GABRA5 (both encoding subunits of GABA A receptor), GOLGA6L2, HERC2 and OCA2 (associated with oculocutaneous albinism II). The deletion 2q21.3 includes exons of the genes RAB3GAP1 (associated with Warburg Micro syndrome) and ZRANB3 (not disease-associated). Despite the normal phenotype of the mother, the relevance of the 2q21.3 microdeletion for the phenotype of the patient cannot be excluded, and further case reports will need to address this point. 相似文献
110.
Mutations in neuronal voltage-gated sodium channel genes SCN1A, SCN2A, and SCN3A may play an important role in the etiology of neurological diseases and psychiatric disorders, besides various types of epilepsy. Here we describe a 3-year-old boy with autistic features, language delay, microcephaly and no history of seizures. Array-CGH analysis revealed an interstitial deletion of ~ 291.9 kB at band 2q24.3 disrupting the entire SCN2A gene and part of SCN3A. We discuss the effects of haploinsufficiency of SCN2A and SCN3A on the genetic basis of neurodevelopmental and neurobehavioral disorders and we propose that this haploinsufficiency may be associated not only with epilepsy, but also with autistic features. 相似文献