ARTICLE | doi:10.3390/sci1020033
Online: 1 July 2019 (00:00:00 CEST)
Nucleolin is an RNA binding protein that is involved in many post-transcriptional regulation steps of messenger RNAs in addition to its nucleolar role in ribosomal RNA transcription and assembly in pre-ribosomes. Acetylated nucleolin was found to be associated with nuclear speckles and to co-localize with the splicing factor SC35. Previous nuclear pull down of nucleolin identified several splicing components and factors involved in RNA polymerase II transcription associated with nucleolin. In this report, we show that these splicing components are specifics of the pre-catalytic A and B spliceosomes, while proteins recruited in the Bact, C and P complexes are absent from the nucleolin interacting proteins. Furthermore, we show that acetylated nucleolin co-localized with P-SF3B1, a marker of co-transcriptional active spliceosomes. P-SF3B1 complexes can be pulled down with nucleolin specific antibodies. Interestingly, the alternative splicing of Fibronectin at the IIICS and EDB sites was affected by nucleolin depletion. These data are consistent with a model where nucleolin could be a factor bridging RNA polymerase II transcription and assembly of pre-catalytic spliceosome similarly to its function in the co-transcriptional maturation of pre-rRNA.
ARTICLE | doi:10.20944/preprints202107.0181.v1
Subject: Chemistry, Analytical Chemistry Keywords: SARS-CoV-2 detection; Immunofluorescence; Paper-based diagnostic device
Online: 7 July 2021 (13:18:33 CEST)
We report on an immunofluorescent paper-based assay for the detection of severe acute respiratory symptom coronavirus 2 (SARS-CoV-2) humanized antibody. The paper-based device was fabricated by using lamination technique for easy and optimized handling. Our approach utilises a two-step strategy that involves (i) initial coating of the paper-electrode with recombinant SARS-CoV-2 nucleocapsid antigen to capture the target SARS-CoV-2 specific antibodies, and (ii) subsequent detection of SARS-CoV-2 antibodies using fluorophore-conjugated IgG antibody. The fluorescence readout was observed with fluorescence microscopy. The images were processed and quantified using a MATLAB program. The assay can selectively detect SARS-CoV-2 humanized antibodies spiked in PBS and healthy human serum samples with the relative standard deviation of approximately 6.4% (for n = 3). It has broad dynamic ranges (1 ng to 50 ng/µL in PBS and 5 to 100 ng/µL in human serum samples) for SARS-CoV-2 humanized antibodies with the detection limits of 2 ng/µL (0.025 IU/mL) and 10 ng/µL (0.125 IU/mL) in PBS and human serum samples, respectively. We believe that our assay has the potential to be used as a simple, rapid, and inexpensive paper-based diagnostic device with a portable fluorescent reader to provide point-of-care diagnosis. This assay can be used for rapid examination of a large batch of samples toward clinical screening of SARS-CoV-2 specific antibodies as a confirmed infected active case or to evaluate the immune response to a SARS-CoV-2 vaccine.
Subject: Medicine & Pharmacology, Other Keywords: inherited platelet disorders; hereditary thrombocytopenias; blood smear; immunofluorescence; bleeding tendency
Online: 20 January 2020 (09:50:59 CET)
Inherited platelet disorders (IPDs) are rare diseases featured by low platelet count and/or defective platelet function. Patients have variable bleeding diathesis and sometimes additional features that can be congenital or acquired. Identification of an IPD is desirable to avoid misdiagnosis of immune thrombocytopenia and use of improper treatments. Diagnostic tools include platelet function studies and genetic testing. The latter can be challenging as the correlation of its outcomes with phenotype is not easy. The immune-morphological evaluation of blood smear (by light- and immunofluorescence microscopy) represents a reliable method to phenotype subjects with suspected IPD. It is relatively cheap, not excessively time-consuming, and applicable to shipped samples. In some forms, it can provide diagnosis by itself, as for MYH9-RD, or in addition to other first-line tests as aggregometry or flow cytometry. In regard to genetic testing, it can guide specific sequencing. Since only minimal amounts of blood are needed for preparation of blood smears, it can be used to further characterize thrombocytopenia in pediatric patients and even newborns. In principle it is based on visualizing alterations in the distribution of proteins, which result from specific genetic mutations, by using monoclonal antibodies. It can be applied to identify deficiencies in membrane proteins, disturbed distribution of cytoskeletal proteins, and alpha as well as delta granules. On the other hand mutations associated with impaired signal transduction are difficult to identify by immunofluorescence of blood smears. This review summarizes technical aspects and the main diagnostic patterns achievable by this method.
CASE REPORT | doi:10.20944/preprints201803.0211.v1
Subject: Medicine & Pharmacology, Oncology & Oncogenics Keywords: MTC; calcitonin; parafollicular C cells; secretory granules; immunofluorescence; ultrastructure; transmission electron microscopy; ERBB1; ERBB2
Online: 26 March 2018 (09:05:18 CEST)
Medullary thyroid carcinomas (MTCs) are rare thyroid tumors occurring in both sporadic and hereditary forms and whose pathogenesis is related to RET proto-oncogene alterations. MTCs originate from parafollicular cells, which produce calcitonin that represents the biochemical activity of MTC. Total thyroidectomy is the main treatment for MTC and often cures patients with confined diseases. In cases of metastasis, the approach depends on the rate of progression of disease. We report a case of a 54 years old female with a single, incidentally discovered, thyroid nodule of 1 cm, classified as suspicious MTC after a stimulation test with i.v. calcium. After surgery, we examined the nodule using immunohistochemistry, immunofluorescence and electron microscopy. In addition to calcitonin, we found that it expressed intracellular positivity for the RTK receptors ERBB1 and ERBB2. Consistently with MTC features, ultrastructural examination of the tumor displayed heterogeneous spindle-shaped cells containing two groups of secretory granules. Due to the significant correlation found between high ERBB1/ERBB2 levels in MTCs and extrathyroidal growth, the detection of ERBB1 and ERBB2 expression suggests that the two oncoproteins may possibly be involved in tumor proliferative responses and/or differentiation of C-cells. The biological, prognostic and therapeutic significance of these patterns would merits further investigations.
BRIEF REPORT | doi:10.20944/preprints202207.0220.v1
Subject: Life Sciences, Virology Keywords: Hepatitis B virus; HepG2-NTCP cells; Immunofluorescence; Sodium taurocholate cotransporting polypeptide (NTCP) Receptor; Subcloning; Limiting dilution; Myrcludex B
Online: 14 July 2022 (12:06:08 CEST)
HepG2 cells reconstituted with Hepatitis B virus (HBV) entry receptor sodium taurocholate co-transporting polypeptide (NTCP) are widely used as a convenient in vitro cell culture infection model for HBV replication studies. As such, it is pertinent that HBV infectivity is maintained at steady-state levels for accurate interpretation of in vitro data. However, variations in HBV infection efficiency due to imbalanced NTCP expression levels in the HepG2 cell line may affect experimental results. In this study, we performed single cell cloning of HepG2-NTCP-A3 parental cells via limiting dilution and obtained multiple subclones with increased permissiveness to HBV. Specifically, one subclone (HepG2-NTCP-A3/C2) yielded more than 4-fold higher HBV infection compared to the HepG2-NTCP-A3 parental clone. In addition, though HBV infectivity was universally reduced in the absence of polyethylene glycol (PEG), subclone C2 maintained relatively greater permissiveness under PEG-free conditions, suggesting the functional heterogeneity within parental HepG2-NTCP-A3 may be exploitable in developing a PEG-free HBV infection model. The increased viral production correlated with increased intracellular viral antigen expression as evidenced through HBcAg immunofluorescence staining. Further, these subclones were found to express different levels of NTCP, albeit with no remarkable morphology or cell growth differences. In conclusion, we isolated subclones of HepG2-NTCP-A3 which support efficient HBV production and thus provide an improved in vitro HBV infection model.
ARTICLE | doi:10.20944/preprints202007.0408.v1
Subject: Medicine & Pharmacology, Other Keywords: Wharton’s Jelly human umbilical cord mesenchymal stem cells (hWJ-MSCs); Growth Differentiation Factor-5; human bone marrow Mesenchymal Stem Cells (hBM-MSCs); tenogenic commitment; gene expression; immunofluorescence assay
Online: 19 July 2020 (11:02:01 CEST)
Mesenchymal Stem Cells derived from bone marrow (hBM-MSCs) are utilized in tendon tissue‐engineering protocols while extra-embryonic cord-derived, including from Wharton’s Jelly (hWJ-MSC), are emerging as useful alternatives. To explore the tenogenic responsiveness of hBM-MSCs and hWJ-MSCs to hGDF-5 we supplemented each at doses of 1, 10, and 100 ng/mL and determined proliferation, morphology and time-dependent expression of tenogenic markers. We evaluated expression of Collagen types 1 (COL1A1) and 3 (COL3A1), Decorin (DCN), Scleraxis A (SCX-A), Tenascin-C (TNC) and Tenomodulin (TNMD) noting the earliest and largest increase with 100 ng/mL. With 100 ng/mL, hBM-MSCs showed upregulation of SCX-A (1.7-fold) at day 1, TNC (1.3-fold) and TNMD (12-fold) at Day 8. hWJ-MSCs, at the same dose, showed up-regulation of COL1A1 (3-fold), DCN (2.7-fold), SCX (3.8-fold) and TNC (2.3-fold) after 3 days of culture. hWJ-MSCs also showed larger proliferation rate and marked aggregation into a tubular shaped system at Day 7 (with 100 ng/mL of hGDF-5). Simultaneous to this we explored expression of pro-inflammatory (IL-6, TNF, IL-12A, IL-1β) and anti-inflammatory (IL-10, TGF-β1) cytokines across for both cell types. hBM-MSCs exhibited a better balance of pro-inflammatory and anti-inflammatory cytokines upregulating IL-1β (11-fold) and IL-10 (10-fold) at Day 8; hWJ-MSCs, had a slight expression of IL-12A (1.5-fold) but a greater up-regulation of IL-10 (2.5-fold). Collagen type I and tenomodulin proteins, detected by immunofluorescence, confirming the greater protein expression when 100 ng/mL were supplemented. In the same conditions, both cell types showed specific alignment and shape modification (fibroblast-like) with a Lenght/Width ratio increase at value higher than 1, suggesting their response in activating tenogenic commitment events, and they both potential use in 3D in vitro tissue engineering protocols.