Glyceraldehyde-3-phosphate dehydrogenase is a reliable internal control in Western blot analysis of leukocyte subpopulations from children

ACTB and GAPDH appear at multiple SDS-PAGE positions, thus not suitable as reference genes for determining protein loading in techniques like Western blotting

We performed polyacrylamide gel electrophoresis of human proteins with sodium dodecyl sulfate, isolated proteins at multiple positions, and then used liquid chromatography and tandem mass spectrometry (LC-MS/MS) to determine the protein identities. Although beta-actin (ACTB) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) are 41.7 and 36 kDa proteins, respectively, LC-MS/MS identified their peptides at all the positions studied. The National Center for Biotechnology Information (USA) database lists only one ACTB mRNA but five GAPDH mRNAs and one noncoding RNA. The five GAPDH mRNAs encode three protein isoforms, while our bioinformatics analysis identified a 17.6 kDa isoform encoded by the noncoding RNA. All LC-MS/MS-identified GAPDH peptides at all positions studied are unique, but some of the identified ACTB peptides are shared by ACTC1, ACTBL2, POTEF, POTEE, POTEI, and POTEJ. ACTC1 and ACTBL2 belong to the ACT family with significant similarities to ACTB in protein sequence, whereas the four POTEs are ACTB-containing chimeric genes with the C-terminus of their proteins highly similar to the ACTB. These data lead us to conclude that GAPDH and ACTB are poor reference genes for determining the protein loading in such techniques as Western blotting, a leading role these two genes have been playing for decades in biomedical research.

Identifying new sperm Western blot loading controls

The measurement of protein expression level plays a pivotal role in both biological and medical studies. Housekeeping proteins, generally encoded by housekeeping genes are used as loading control proteins to normalize protein expression. Obviously, proper reference standards are essential for adequate analysis of protein expression. However, our study showed that the widely used normalisation proteins, whose expression levels varied greatly among sperm samples, were unsuitable for data standardisation. To uncover the proteins steadily expressed in sperm, we analysed several published transcriptome data of sperm. Seven proteins whose expression levels were relatively stable (co-efficient variation values less than 0.35) were selected and further evaluated by quantitative real-time polymerase chain reaction, Western Blot (WB) and immunocytochemistry. Our results showed that among the classical housekeeping proteins, only β-tubulin remained constant in sperm samples from 85 individuals. Compared with other classical housekeeping proteins such as glyceraldehyde 3-phosphate dehydrogenase, actin and histone H3, Cullin-1 (CUL1) and F-box only protein 7 (FBXO7) seemed to be more suitable to be used as internal controls for WB in sperm protein studies. Combined with the locations of these proteins, CUL1 and FBXO7 were suggested to be used as a housekeeping protein for total proteins.

Investigating the role of striatal dopamine receptor 2 in motor coordination and balance: Insights into the pathogenesis of DYT1 dystonia

DYT1 or DYT-TOR1A dystonia is early-onset, generalized dystonia. Most DYT1 dystonia patients have a heterozygous trinucleotide GAG deletion in DYT1 or TOR1A gene, with a loss of a glutamic acid residue of the protein torsinA. DYT1 dystonia patients show reduced striatal dopamine D2 receptor (D2R) binding activity. We previously reported reduced striatal D2R proteins and impaired corticostriatal plasticity in Dyt1 ΔGAG heterozygous knock-in (Dyt1 KI) mice. It remains unclear how the D2R reduction contributes to the pathogenesis of DYT1 dystonia. Recent knockout studies indicate that D2R on cholinergic interneurons (Chls) has a significant role in corticostriatal plasticity, while D2R on medium spiny neurons (MSNs) plays a minor role. To determine how reduced D2Rs on ChIs and MSNs affect motor performance, we generated ChI- or MSN-specific D2R conditional knockout mice (Drd2 ChKO or Drd2 sKO). The striatal ChIs in the Drd2 ChKO mice showed an increased firing frequency and impaired quinpirole-induced inhibition, suggesting a reduced D2R function on the ChIs. Drd2 ChKO mice had an age-dependent deficient performance on the beam-walking test similar to the Dyt1 KI mice. The Drd2 sKO mice, conversely, had a deficit on the rotarod but not the beam-walking test. Our findings suggest that D2Rs on Chls and MSNs have critical roles in motor control and balance. The similarity of the beam-walking deficit between the Drd2 ChKO and Dyt1 KI mice supports our earlier notion that D2R reduction on striatal ChIs contributes to the pathophysiology and the motor symptoms of DYT1 dystonia.

MiR155-5p in adventitial fibroblasts-derived extracellular vesicles inhibits vascular smooth muscle cell proliferation via suppressing angiotensin-converting enzyme expression

Proliferation of vascular smooth muscle cells (VSMCs) plays crucial roles in vascular remodelling and stiffening in hypertension. Vascular adventitial fibroblasts are a key regulator of vascular wall function and structure. This study is designed to investigate the roles of adventitial fibroblasts-derived extracellular vesicles (EVs) in VSMC proliferation and vascular remodelling in normotensive Wistar-Kyoto rat (WKY) and spontaneously hypertensive rat (SHR), an animal model of human essential hypertension. EVs were isolated from aortic adventitial fibroblasts of WKY (WKY-EVs) and SHR (SHR-EVs). Compared with WKY-EVs, miR155-5p content was reduced, while angiotensin-converting enzyme (ACE) content was increased in SHR-EVs. WKY-EVs inhibited VSMC proliferation of SHR, which was prevented by miR155-5p inhibitor. SHR-EVs promoted VSMC proliferation of both strains, which was enhanced by miR155-5p inhibitor, but abolished by captopril or losartan. Dual luciferase reporter assay showed that ACE was a target gene of miR155-5p. MiR155-5p mimic or overexpression inhibited VSMC proliferation and ACE upregulation of SHR. WKY-EVs reduced ACE mRNA and protein expressions while SHR-EVs only increased ACE protein level in VSMCs of both strains. However, the SHR-EVs-derived from the ACE knockdown-treated adventitial fibroblasts lost the roles in promoting VSMC proliferation and ACE upregulation. Systemic miR155-5p overexpression reduced vascular ACE, angiotensin II and proliferating cell nuclear antigen levels, and attenuated hypertension and vascular remodelling in SHR. Repetitive intravenous injection of SHR-EVs increased blood pressure and vascular ACE contents, and promoted vascular remodelling in both strains, while WKY-EVs reduced vascular ACE contents and attenuated hypertension and vascular remodelling in SHR. We concluded that WKY-EVs-mediated miR155-5p transfer attenuates VSMC proliferation and vascular remodelling in SHR via suppressing ACE expression, while SHR-EVs-mediated ACE transfer promotes VSMC proliferation and vascular remodelling.

Pathological alterations of chondroitin sulfate moiety in postmortem hippocampus of patients with schizophrenia

Perineuronal nets comprise chondroitin sulfate moieties and their core proteins, and their neuropathological alterations have been implicated in schizophrenia. To explore the molecular mechanism of the perineuronal net impairments in schizophrenia, we measured the immunoreactivity of chondroitin sulfate moieties, major components of perineuronal nets, in three brain regions (postmortem dorsolateral prefrontal cortex, caudate nucleus, and hippocampus) of schizophrenia patients and control subjects. Immunoblotting for chondroitin 4-sulfate and chondroitin 6-sulfate moieties revealed a significant increase in intensity of a 180 kD band of chondroitin 4-sulfate immunoreactivity in the hippocampus of patients, although we detected no significant alteration in their immunoreactivities with any other molecular sizes or in other brain regions. The levels of immunoreactivity were not correlated with postmortem interval, age, or storage time. We failed to find such an increase in a similar molecular range of the chondroitin 4-sulfate immunoreactivity in the hippocampus of the rats chronically treated with haloperidol. These results suggest that the level alteration of the chondroitin 4-sulfate moiety might contribute to the perineuronal net abnormality found in patients with schizophrenia.

Tubulin or Not Tubulin: Heading Toward Total Protein Staining as Loading Control in Western Blots

Western blotting is an analytical method widely used for detecting and (semi-)quantifying specific proteins in given samples. Western blots are continuously applied and developed by the protein community. This review article focuses on a significant, but not yet well-established, improvement concerning the internal loading control as a prerequisite to accurately quantifying Western blots. Currently, housekeeping proteins (HKPs) like actin, tubulin, or GAPDH are often used to check for equal loading or to compensate potential loading differences. However, this loading control has multiple drawbacks. Staining of the total protein on the blotting membrane has emerged as a better loading control. Total protein staining (TPS) represents the actual loading amount more accurately than HKPs due to minor technical and biological variation. Further, the broad dynamic range of TPS solves the issue of HKPs that commonly fail to show loading differences above small loading amounts of 0.5-10 μg. Although these and further significant advantages have been demonstrated over the past 10 years, only a small percentage of laboratories take advantage of it. The objective of this review article is to collect and compare information about TPS options and to invite users to reconsider their applied loading control. Nine benefits of TPS are discussed and seven different variants are critically evaluated by comparing technical details. Consequently, this review article offers an orientation in selecting the appropriate staining type. I conclude that TPS should be the preferred loading control in future Western blot approaches.

Preparation and characterization of universal Fe3O4@SiO2/CdTe nanocomposites for rapid and facile detection and separation of membrane proteins

The separation and enrichment of cell membrane proteins was achieved by the construction of bi-functional magnetic fluorescent nanoprobes.

Comparison of the Functional microRNA Expression in Immune Cell Subsets of Neonates and Adults

Diversity of biological molecules in newborn and adult immune cells contributes to differences in cell function and atopic properties. Micro RNAs (miRNAs) are reported to involve in the regulation of immune system. Therefore, determining the miRNA expression profile of leukocyte subpopulations is important for understanding immune system regulation. In order to explore the unique miRNA profiling that contribute to altered immune in neonates, we comprehensively analyzed the functional miRNA signatures of eight leukocyte subsets (polymorphonuclear cells, monocytes, CD4⁺ T cells, CD8⁺ T cells, natural killer cells, B cells, plasmacytoid dendritic cells, and myeloid dendritic cells) from both neonatal and adult umbilical cord and peripheral blood samples, respectively. We observed distinct miRNA profiles between adult and neonatal blood leukocyte subsets, including unique miRNA signatures for each cell lineage. Leukocyte miRNA signatures were altered after stimulation. Adult peripheral leukocytes had higher let-7b-5p expression levels compared to neonatal cord leukocytes across multiple subsets, irrespective of stimulation. Transfecting neonatal monocytes with a let-7b-5p mimic resulted in a reduction of LPS-induced interleukin (IL)-6 and TNF-α production, while transfection of a let-7b-5p inhibitor into adult monocytes enhanced IL-6 and TNF-α production. With this functional approach, we provide intact differential miRNA expression profiling of specific immune cell subsets between neonates and adults. These studies serve as a basis to further understand the altered immune response observed in neonates and advance the development of therapeutic strategies.

Selection of Suitable Reference Genes for Analysis of Salivary Transcriptome in Non-Syndromic Autistic Male Children

Childhood autism is a severe form of complex genetically heterogeneous and behaviorally defined set of neurodevelopmental diseases, collectively termed as autism spectrum disorders (ASD). Reverse transcriptase quantitative real-time PCR (RT-qPCR) is a highly sensitive technique for transcriptome analysis, and it has been frequently used in ASD gene expression studies. However, normalization to stably expressed reference gene(s) is necessary to validate any alteration reported at the mRNA level for target genes. The main goal of the present study was to find the most stable reference genes in the salivary transcriptome for RT-qPCR analysis in non-syndromic male childhood autism. Saliva samples were obtained from nine drug naïve non-syndromic male children with autism and also sex-, age-, and location-matched healthy controls using the RNA-stabilizer kit from DNA Genotek. A systematic two-phased measurement of whole saliva mRNA levels for eight common housekeeping genes (HKGs) was carried out by RT-qPCR, and the stability of expression for each candidate gene was analyzed using two specialized algorithms, geNorm and NormFinder, in parallel. Our analysis shows that while the frequently used HKG ACTB is not a suitable reference gene, the combination of GAPDH and YWHAZ could be recommended for normalization of RT-qPCR analysis of salivary transcriptome in non-syndromic autistic male children.

Regulatory mechanism of human vascular smooth muscle cell phenotypic transformation induced by NELIN

Vascular disorders, including hypertension, atherosclerosis and restenosis, arise from dysregulation of vascular smooth muscle cell (VSMC) differentiation, which can be controlled by regulatory factors. The present study investigated the regulatory mechanism of the phenotypic transformation of human VSMCs by NELIN in order to evaluate its potential as a preventive and therapeutic of vascular disorders. An in vitro model of NELIN-overexpressing VSMCs was prepared by transfection with a lentiviral (LV) vector (NELIN-VSMCs) and NELIN was slienced using an a lentiviral vector with small interfering (si)RNA in another group (LV-NELIN-siRNA-VSMCs). The effects of NELIN overexpression or knockdown on the phenotypic transformation of human VSMCs were observed, and its regulatory mechanism was studied. Compared with the control group, cells in the NELIN-VSMCs group presented a contractile phenotype with a significant increase of NELIN mRNA, NELIN protein, smooth muscle (SM)α-actin and total Ras homolog gene family member A (RhoA) protein expression. The intra-nuclear translocation of SMα-actin-serum response factor (SMα-actin-SRF) occurred in these cells simultaneously. Following exposure to Rho kinsase inhibitor Y-27632, SRF and SMα-actin expression decreased. However, cells in the LV-NELIN-siRNA-VSMCs group presented a synthetic phenotype, and the expression of NELIN mRNA, NELIN protein, SMα-actin protein and total RhoA protein was decreased. The occurrence of SRF extra-nuclear translocation was observed. In conclusion, the present study suggested that NELIN was able to activate regulatory factors of SMα-actin, RhoA and SRF successively in human VSMCs cultured in vitro. Furthermore, NELIN-induced phenotypic transformation of human VSMCs was regulated via the RhoA/SRF signaling pathway. The results of the present study provide a foundation for the use of NELIN in preventive and therapeutic treatment of vascular remodeling diseases, including varicosity and atherosclerosis.

Fish oil supplementation associated with decreased cellular degeneration and increased cellular proliferation 6 weeks after middle cerebral artery occlusion in the rat

Anti-inflammatory long-chain omega-3 polyunsaturated fatty acids (n-3-LC-PUFAs) are both neuroprotective and have antidepressive effects. However the influence of dietary supplemented n-3-LC-PUFAs on inflammation-related cell death and proliferation after middle cerebral artery occlusion (MCAo)-induced stroke is unknown. We have previously demonstrated that anxiety-like and hyperactive locomotor behaviors are reduced in n-3-LC-PUFA-fed MCAo animals. Thus in the present study, male hooded Wistar rats were exposed to MCAo or sham surgeries and examined behaviorally 6 weeks later, prior to euthanasia and examination of lesion size, cell death and proliferation in the dentate gyrus, cornu ammonis region of the hippocampus of the ipsilesional hemispheres, and the thalamus of the ipsilesional and contralesional hemispheres. Markers of cell genesis and cell degeneration in the hippocampus or thalamus of the ipsilesional hemisphere did not differ between surgery and diet groups 6 weeks post MCAo. Dietary supplementation with n-3-LC-PUFA decreased cell degeneration and increased cell proliferation in the thalamic region of the contralesional hemisphere. MCAo-associated cell degeneration in the hippocampus and thalamus positively correlated with anxiety-like and hyperactive locomotor behaviors previously reported in these animals. These results suggest that anti-inflammatory n-3-LC-PUFA supplementation appears to have cellular protective effects after MCAo in the rat, which may affect behavioral outcomes.

GAPDH and β-actin protein decreases with aging, making Stain-Free technology a superior loading control in Western blotting of human skeletal muscle

Reference proteins (RP) or the total protein (TP) loaded is used to correct for uneven loading and/or transfer in Western blotting. However, the signal sensitivity and the influence of physiological conditions may question the normalization methods. Therefore, three widely used reference proteins [β-actin, glyceraldehyde 3-phosphate dehydrogenase (GAPDH), and α-tubulin], as well as TP loaded measured by Stain-Free technology (SF) as normalization tool were tested. This was done using skeletal muscle samples from men subjected to physiological conditions often investigated in applied physiology where the intervention has been suggested to impede normalization (ageing, muscle atrophy, and different muscle fiber type composition). The linearity of signal and the methodological variation coefficient was obtained. Furthermore, the inter- and intraindividual variation in signals obtained from SF and RP was measured in relation to ageing, muscle atrophy, and different muscle fiber type composition, respectively. A stronger linearity of SF and β-actin compared with GAPDH and α-tubulin was observed. The methodological variation was relatively low in all four methods (4-11%). Protein level of β-actin and GAPDH was lower in older men compared with young men. In conclusion, β-actin, GAPDH, and α-tubulin may not be used for normalization in studies that include subjects with a large age difference. In contrast, the RPs may not be affected in studies that include muscle wasting and differences in muscle fiber type. The novel SF technology adds lower variation to the results compared with the existing methods for correcting for loading inaccuracy in Western blotting of human skeletal muscle in applied physiology.

L-Arginine modulates neonatal lymphocyte proliferation through an interleukin-2 independent pathway

In cases of arginine depletion, lymphocyte proliferation, cytokine production and CD3ζ chain expression are all diminished. In addition to myeloid suppressor cells, polymorphonuclear cells (PMN) also exert T-cell immune suppressive effects through arginase-induced l-arginine depletion, especially during pregnancy. In this study, we investigated how arginase/l-arginine modulates neonatal lymphocyte proliferation. Results showed that the neonatal plasma l-arginine level was lower than in adults (48·1 ± 11·3 versus 86·5 ± 14·6 μm; P = 0·003). Neonatal PMN had a greater abundance of arginase I protein than adult PMN. Both transcriptional regulation and post-transcriptional regulation were responsible for the higher arginase I expression of neonatal PMN. Exogenous l-arginine enhanced neonate lymphocyte proliferation but not that of adult cells. The RNA-binding protein HuR was important but was not the only modulation factor in l-arginine-regulated neonatal T-cell proliferation. l-Arginine-mediated neonatal lymphocyte proliferation could not be blocked by interleukin-2 receptor blocking antibodies. These results suggest that the altered arginase/l-arginine cascade may be one of the mechanisms that contribute to altered neonatal immune responses. Exogenous l-arginine could enhance neonate lymphocyte proliferation through an interleukin-2-independent pathway.

An old method facing a new challenge: re-visiting housekeeping proteins as internal reference control for neuroscience research

The study of specific target protein expression is often performed by western blotting, a commonly used method to measure the protein expression in neuroscience research by specific antibodies. Housekeeping proteins are used as an internal control for protein loading as well as reference in the western blotting analysis. This practice is based on the belief that such housekeeping genes are considered to be ubiquitously and constitutively expressed in every tissue and produce the minimal essential transcripts necessary for normal cellular function. The most commonly used housekeeping proteins are β-actin, β-tubulin, and glyceraldehyde 3-phosphate dehydrogenase (GAPDH). However, recent studies have shown significant variation in some housekeeping genes both at the mRNA and protein levels in various neuropathological events, such as spinal cord injury and Alzheimer's diseases. Changes of housekeeping genes are also induced by non-neuronal diseases in various tissues. Therefore, these discoveries raise a potential concern regarding whether using a housekeeping protein as an internal standard for target protein analysis is an appropriate practice. This minireview will focus on (I) the effects of neuronal and non-neuronal diseases, experimental condition, and tissue-specific roles on alteration of housekeeping genes, and (II) alternative internal standards for gene and protein expression analysis.

Different modulating effects of adenosine on neonatal and adult polymorphonuclear leukocytes

Polymorphonuclear leukocytes (PMNs) are the major leukocytes in the circulation and play an important role in host defense. Intact PMN functions include adhesion, migration, phagocytosis, and reactive oxygen species (ROS) release. It has been known for a long time that adenosine can function as a modulator of adult PMN functions. Neonatal plasma has a higher adenosine level than that of adults; however, little is known about the modulating effects of adenosine on neonatal PMNs. The aim of this study was to investigate the effects of adenosine on neonatal PMN functions. We found that neonatal PMNs had impaired adhesion, chemotaxis, and ROS production abilities, but not phagocytosis compared to adult PMNs. As with adult PMNs, adenosine could suppress the CD11b expressions of neonatal PMNs, but had no significant suppressive effect on phagocytosis. In contrast to adult PMNs, adenosine did not significantly suppress chemotaxis and ROS production of neonatal PMNs. This may be due to impaired phagocyte reactions and a poor neonatal PMN response to adenosine. Adenosine may not be a good strategy for the treatment of neonatal sepsis because of impaired phagocyte reactions and poor response.

Glyceraldehyde-3-phosphate dehydrogenase: a universal internal control for Western blots in prokaryotic and eukaryotic cells

In the current study, we examined the expression level of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) protein in a number of organisms and the stability of GAPDH under various conditions. Our results revealed that GAPDH is present in multiple Escherichia coli strains, the yeast strain GS115, Caenorhabditis elegans, rat PC12 cells, and both mouse and rat brain. Furthermore, GAPDH was stably expressed under different concentrations of inducer and at different times of induction in E. coli (BL21) cells and yeast GS115 cells. Stable expression of GAPDH protein was also observed in C.elegans and PC12 cells that were treated with different concentrations of paraquat or sodium sulfite, respectively. In addition, we were able to detect and identify the endogenous gapA protein in E.coli via immunoprecipitation and MALDI-TOF-MS analysis. Endogenous gapA protein and exogenously expressed (subcloned) GAPDH proteins were detected in E. coli BL21 but not for gapC. With the exception of gapC in E. coli, the various isoforms of GAPDH possessed enzymatic activity. Finally, sequence analysis revealed that the GAPDH proteins were 76% identical, with the exception of E. coli gapC. Taken together, our results indicate that GAPDH could be universally used as an internal control for the Western blot analysis of prokaryotic and eukaryotic samples.