Thiamin (vitamin B1), a member of the water-soluble family of vitamins, is essential for normal cellular functions; its deficiency results in oxidative stress and mitochondrial dysfunction. Pancreatic acinar cells (PAC) obtain thiamin from the circulation using a specific carrier-mediated process mediated by both thiamin transporters -1 and -2 (THTR-1 and THTR-2; encoded by the SLC19A2 and SLC19A3 genes, respectively). The aim of the current study was to examine the effect of chronic exposure of mouse PAC in vivo and human PAC in vitro to nicotine (a major component of cigarette smoke that has been implicated in pancreatic diseases) on thiamin uptake and to delineate the mechanism involved. The results showed that chronic exposure of mice to nicotine significantly inhibits thiamin uptake in murine PAC, and that this inhibition is associated with a marked decrease in expression of THTR-1 and THTR-2 at the protein, mRNA and hnRNAs level. Furthermore, expression of the important thiamin-metabolizing enzyme, thiamin pyrophosphokinase (TPKase), was significantly reduced in PAC of mice exposed to nicotine. Similarly, chronic exposure of cultured human PAC to nicotine (0.5 μM, 48 h) significantly inhibited thiamin uptake, which was also associated with a decrease in expression of THTR-1 and THTR-2 proteins and mRNAs. This study demonstrates that chronic exposure of PAC to nicotine impairs the physiology and the molecular biology of the thiamin uptake process. Furthermore, the study suggests that the effect is, in part, mediated through transcriptional mechanism(s) affecting the SLC19A2 and SLC19A3 genes.

Group B streptococci (GBS; Streptococcus agalactiae) are the leading cause of neonatal invasive diseases and are also important pathogens for elderly adults. Until now, nearly all GBS with reduced penicillin susceptibility (PRGBS) have shown β-hemolytic activity and grow on sheep blood agar. However, we have previously reported three PRGBS clinical isolates harboring a CylK deletion that form small less hemolytic colonies. In this study, we examined the causes of small, less hemolytic colony formation in these clinical isolates. Isogenic strains were sequenced to identify the mutation related to a small colony size. We identified a 276_277insG nucleic acid insertion in the thiamin pyrophosphokinase (tpk) gene, resulting in premature termination at amino acid 103 in TPK, as a candidate mutation responsible for small colony formation. The recombinant strain Δtpk, which harbored the 276_277insG insertion in the tpk gene, showed small colony formation. The recombinant strain ΔcylK, which harbored the G379T substitution in cylK, showed a reduction in hemolytic activity. The phenotypes of both recombinant strains were complemented by the expression of intact TPK or CylK, respectively. Moreover, the use of Rapid ID 32 API and VITEK MS to identify strains as GBS was evaluated clinical isolates and recombinant strains. VITEK MS, but not Rapid ID 32 API, was able to accurately identify the strains as GBS. In conclusion, we determined that mutations in tpk and cylK caused small colonies and reduced hemolytic activity, respectively, and characterized the clinical isolates in detail.

The human malaria parasite Plasmodium falciparum expresses variant PfEMP1 proteins on the infected erythrocyte, which function as ligands for endothelial receptors in capillary vessels, leading to erythrocyte sequestration and severe malaria. The factors that orchestrate the mono-allelic expression of the 45-90 PfEMP1-encoding var genes within each parasite genome are still not fully identified. Here, we show that the transcription factor PfAP2-O influences the transcription of var genes. The temporary knockdown of PfAP2-O leads to a complete loss of var transcriptional memory and a decrease in cytoadherence in CD36 adherent parasites. AP2-O-knocked-down parasites exhibited also significant reductions in transmission through Anopheles mosquitoes. We propose that PfAP2-O is, beside its role in transmission stages, also one of the virulence gene transcriptional regulators and may therefore be exploited as an important target to disrupt severe malaria and block parasite transmission.

Although we now routinely sequence human genomes, we can confidently identify only a fraction of the sequence variants that have a functional impact. Here, we developed a deep mutational scanning framework that produces exhaustive maps for human missense variants by combining random codon mutagenesis and multiplexed functional variation assays with computational imputation and refinement. We applied this framework to four proteins corresponding to six human genes: UBE2I (encoding SUMO E2 conjugase), SUMO1 (small ubiquitin-like modifier), TPK1 (thiamin pyrophosphokinase), and CALM1/2/3 (three genes encoding the protein calmodulin). The resulting maps recapitulate known protein features and confidently identify pathogenic variation. Assays potentially amenable to deep mutational scanning are already available for 57% of human disease genes, suggesting that DMS could ultimately map functional variation for all human disease genes.

Minocycline (MH) is a broad-spectrum antimicrobial agent and semisynthetic tetracycline derivative, which has been widely used in the clinic due to its efficacy. Having the strongest anti-microbial effect, MH exceeded the traditional scope of antibiotics and its previously unknown antifungal activity is also gradually being discovered. To preliminarily investigate the inhibitory effect of MH on Candida albicans (C. albicans), changes of cell growth, hyphal formation and transition, biofilm production and signaling pathway gene expression of C. albicans in the presence of MH were assessed in the present study. An XTT reduction assay was performed to quantitatively detect the metabolic activity of biofilms and evaluate the inhibition of MH on this. The results suggested that biofilm formation was clearly inhibited by 67% (P<0.0001) in the presence of 250 µg/ml MH, while mature biofilms were not significantly affected. In addition, MH inhibited the transition from yeast to hypha in a dose-dependent manner. Furthermore, reverse transcription-quantitative PCR revealed that several hyphae- and adhesion-specific genes associated with the Ras/cyclic (c)AMP/protein kinase A (PKA) pathway were differentially expressed following MH treatment, including downregulation of ras family GTPase (RAS1), adenylyl cyclase-associated protein 1 (CAP1), thiamin pyrophosphokinase 1 (TPK1), adenylate cyclase (CDC35), transcription factor (TEC1), agglutinin-like protein 3 (ALS3) and hyphal wall protein 1 (HWP1) and upregulation of EFG1 (enhanced filamentous growth protein 1 gene) and PDE2 (high-affinity phosphodiesterase gene). The most obviously changed genes were TPK1, HWP1 and RAS1, downregulated by 0.33-, 0.48- and 0.55-fold, respectively. It was suggested that MH is associated with alterations in the morphology of C. albicans, such as the repression of hypha and biofilm formation of cells, and MH affected the Ras/cAMP pathway to regulate the expression of cAMP-associated genes.

Currently, one of the main challenges in human molecular genetics is the interpretation of rare genetic variants of unknown clinical significance. A conclusive diagnosis is of importance for the patient to obtain certainty about the cause of the disease, for the clinician to be able to provide optimal care to the patient and to predict the disease course, and for the clinical geneticist for genetic counseling of the patient and family members. Conclusive evidence for pathogenicity of genetic variants is therefore crucial. This review gives an introduction to the problem of the interpretation of genetic variants of unknown clinical significance in view of the recent advances in genetic screening, and gives an overview of the possibilities for functional tests that can be performed to answer questions about the function of genes and the functional consequences of genetic variants ("functional genomics") in the field of inborn errors of metabolism (IEM), including several examples of functional genomics studies of mitochondrial disorders and several other IEM.

The role of sonic hedgehog (SHH) in epithelial mesenchymal transition (EMT) of pancreatic cancer (PC) is known, however, its mechanism is unclear. Because SHH promotes tumor development predominantly through Gli1, we sought to understand its mechanism by identifying Gli1 targets in pancreatic cancer cells.