Differential regulation of stem cell factor mRNA expression in human endothelial cells by bacterial pathogens: an in vitro model of inflammation

Abstract Production of hematopoietic growth factors by endothelial cells plays a pivotal role during inflammatory processes. Stem cell factor (SCF) is known to be expressed constitutively in endothelial cells. To investigate the regulation of this cytokine expression by inflammatory stimuli, we cocultured human umbilical vein endothelial cells (HUVEC) with various gram-negative bacterial strains (Escherichia coli, Yersinia enterocolitica, Chlamydia trachomatis, and Neisseria meningitidis, respectively). Experiments were performed with bacterial concentrations ranging from 10(2) to 10(7) bacteria/mL for 3 hours. SCF- specific mRNA expression was studied using Northern blot analysis. Stimulation with the enteropathogenic bacterial strains Y enterocolitica and E coli resulted in a significant concentration- dependent increase of SCF mRNA expression. Similar results were obtained in coculture experiments with N meningitidis. As shown in experiments with E coli, the accumulation of SCF transcripts was also time-dependent. In contrast, coculture of HUVEC with the intracellular gram-negative strain C trachomatis had no effect on SCF mRNA expression. To elucidate the role of the gram-negative bacterial cell wall components, we stimulated HUVEC with bacterial lipopolysaccharide (LPS). LPS induced a maximal SCF mRNA accumulation within 2 hours followed by decrease of SCF-specific transcripts to the basal level after 24 hours. In addition, we exposed HUVEC to the classical inflammatory cytokine interleukin-1 alpha (IL-1 alpha). Kinetic experiments showed a similar pattern of regulation with an increase of SCF mRNA within 2 hours, persisting up to 12 hours, and a decrease to basal transcription after 24 hours. From these data, we conclude that SCF expression is regulated by inflammatory stimuli, such as IL-1 alpha and bacterial pathogens, suggesting an important role of SCF during inflammation.

Download Full-text

SYNTHESIS, CHARACTERIZATION AND BIOLOGICAL EVALUATION OF 3-FORMYL INDOLE BASED SCHIFF BASES

Journal of Biomedical and Pharmaceutical Research ◽

10.32553/jbpr.v7i6.561 ◽

2018 ◽

Vol 7 (6) ◽

Author(s):

Singh Gurvinder ◽

Singh Prabhsimran ◽

Dhawan R. K.

Keyword(s):

Antimicrobial Activity ◽

Spectral Analysis ◽

Schiff Bases ◽

Antimicrobial Agents ◽

Biological Evaluation ◽

Fungal Strain ◽

Bacterial Strains ◽

Standard Drug ◽

Gram Negative ◽

E Coli

In order to develop new antimicrobial agents, a series of 3-formyl indole based Schiff bases were synthesized by reacting 3-formyl indole(indole-3-carboxaldehyde) with substituted aniline taking ethanol as solvent. The reaction was carried in the presence of small amount of p-toluene sulphonic acid as catalyst.All the synthesized compounds were characterized by IR, 1H-NMR spectral analysis. All the synthesized compounds were evaluated for antimicrobial activity against two gram positive bacterial strains (B. subtilisand S. aureus) and two gram negative bacterial strains (P. aeruginosaand E. coli) and one fungal strain (C. albicans). All the synthesized compounds were found to have moderate to good antimicrobial activity. The standard drug amoxicillin, fluconazole were used for antimicrobial activity. Among the synthesized compounds, the maximum antimicrobial activity was shown by compounds GS04, GS07, GS08 and GS10.

Download Full-text

Epidemiological and phylogenetic analysis reveals Flavobacteriaceae as potential ancestral source of tigecycline resistance gene tet(X)

Nature Communications ◽

10.1038/s41467-020-18475-9 ◽

2020 ◽

Vol 11 (1) ◽

Author(s):

Rong Zhang ◽

Ning Dong ◽

Zhangqi Shen ◽

Yu Zeng ◽

Jiauyue Lu ◽

...

Keyword(s):

Phylogenetic Analysis ◽

Resistance Gene ◽

Gc Content ◽

Zhejiang Province ◽

Bacterial Strains ◽

Gram Negative ◽

E Coli ◽

Transmission Mechanisms ◽

Low Prevalence ◽

Potential Origin

Abstract Emergence of tigecycline-resistance tet(X) gene orthologues rendered tigecycline ineffective as last-resort antibiotic. To understand the potential origin and transmission mechanisms of these genes, we survey the prevalence of tet(X) and its orthologues in 2997 clinical E. coli and K. pneumoniae isolates collected nationwide in China with results showing very low prevalence on these two types of strains, 0.32% and 0%, respectively. Further surveillance of tet(X) orthologues in 3692 different clinical Gram-negative bacterial strains collected during 1994–2019 in hospitals in Zhejiang province, China reveals 106 (2.7%) tet(X)-bearing strains with Flavobacteriaceae being the dominant (97/376, 25.8%) bacteria. In addition, tet(X)s are found to be predominantly located on the chromosomes of Flavobacteriaceae and share similar GC-content as Flavobacteriaceae. It also further evolves into different orthologues and transmits among different species. Data from this work suggest that Flavobacteriaceae could be the potential ancestral source of the tigecycline resistance gene tet(X).

Download Full-text

The Role of Autophagy During Differentiation and in Enhancing the Longevity of Induced Pluripotent Stem Cell-Derived Endothelial Cells

JVS: Vascular Science ◽

10.1016/j.jvssci.2020.11.017 ◽

2020 ◽

Vol 1 ◽

pp. 254

Author(s):

Katherine E. Hekman ◽

Kyle Koss ◽

David Z. Ivancic ◽

Congcong He ◽

Jason A. Wertheim

Keyword(s):

Endothelial Cells ◽

Stem Cell ◽

Pluripotent Stem Cell ◽

Induced Pluripotent Stem Cell ◽

Induced Pluripotent

Download Full-text

Novel Bacterial Production of Two Different Bioactive Forms of Human Stem-Cell Factor

International Journal of Molecular Sciences ◽

10.3390/ijms22126361 ◽

2021 ◽

Vol 22 (12) ◽

pp. 6361

Author(s):

Eunyoung Lee ◽

Michelle Novais de Paula ◽

Sangki Baek ◽

Huynh Kim Khanh Ta ◽

Minh Tan Nguyen ◽

...

Keyword(s):

Stem Cell ◽

Ion Exchange ◽

Stem Cell Factor ◽

Transmembrane Domain ◽

Coli Strain ◽

Exchange Chromatography ◽

Soluble Form ◽

Human Stem Cell ◽

E Coli ◽

Human Stem Cell Factor

Human stem-cell factor (hSCF) stimulates the survival, proliferation, and differentiation of hematopoietic cells by binding to the c-Kit receptor. Various applications of hSCF require the efficient and reliable production of hSCF. hSCF exists in three forms: as two membrane-spanning proteins hSCF248 and hSCF229 and truncated soluble N-terminal protein hSCF164. hSCF164 is known to be insoluble when expressed in Escherichia coli cytoplasm, requiring a complex refolding procedure. The activity of hSCF248 has never been studied. Here, we investigated novel production methods for recombinant hSCF164 and hSCF248 without the refolding process. To increase the solubility of hSCF164, maltose-binding protein (MBP) and protein disulfide isomerase b’a’ domain (PDIb’a’) tags were attached to the N-terminus of hSCF164. These fusion proteins were overexpressed in soluble form in the Origami 2(DE3) E. coli strain. These solubilization effects were enhanced at a low temperature. His-hSCF248, the poly-His tagged form of hSCF248, was expressed in a highly soluble form without a solubilization tag protein, which was unexpected because His-hSCF248 contains a transmembrane domain. hSCF164 was purified using affinity and ion-exchange chromatography, and His-hSCF248 was purified by ion-exchange and gel filtration chromatography. The purified proteins stimulated the proliferation of TF-1 cells. Interestingly, the EC50 value of His-hSCF248 was 1 pg/mL, 100-fold lower than 9 ng/mL hSCF164. Additionally, His-hSCF248 decreased the doubling time, increased the proportion of S and G2/M stages in the cell cycle, and increased the c-Myc expression at a 1000-fold lower concentration than hSCF164. In conclusion, His-hSCF248 was expressed in a soluble form in E. coli and had stronger activity than hSCF164. The molecular chaperone, MBP, enabled the soluble overexpression of hSCF164.

Download Full-text