Prevalence and Antimicrobial Characteristics of Shiga Toxin-Producing Escherichia coli Isolates from Pork in Korea.

Shiga toxin-producing Escherichia coli (STEC) strains are important food-borne pathogens that can be transmitted through the consumption of food products derived from pigs. Moreover, antimicrobial resistance in STEC has been a matter of increasing concern. The aim of this study was to investigate the prevalence and antimicrobial characteristics of STEC isolates from pork in Korea. We isolated 131 isolates of E. coli from 334 pork samples collected from slaughterhouses and retail markets from 2008 to 2009. Among the 131 isolates, 6 (4.58%) were confirmed to belong to 6 different serotypes of STEC. All six STEC isolates contained stx1 and eaeA virulence genes, and four of them additionally carried the hly gene. The minimum inhibitory concentration (MIC) of 15 antibiotics (amoxicillin/clavulanic acid, ampicillin, cephalothin, cefoxitin, ceftiofur, gentamicin, neomycin, streptomycin, nalidixic acid, ciprofloxacin, colistin, chloramphenicol, florfenicol, tetracycline and sulfamethoxazole/trimethoprim) toward the STEC isolates was determined. As a result, three strains were associated with high MICs for florfenicol and chloramphenicol (64 µg/mL). Furthermore, all three strains were found to contain the florfenicol-resistant gene (floR) but not the chloramphenicol-resistant gene (cat). Sequence alignment and BLAST analysis of the polymerase chain reaction products of the floR gene indicated that they contained sequences with homology to the floR gene of E. coli or Salmonella enterica serovar, Heidelberg. This is the first report on the detection of floR in STEC isolated from pork obtained from retail markets in Korea.

Heterozygous ZNHIT3 variants within the 17q12 recurrent deletion region are associated with Mayer-Rokitansky-Kuster Hauser (MRKH) syndrome.

The molecular basis of mullerian aplasia, also known as Mayer-Rokitansky-Kuster Hauser (MRKH) or congenital absence of the uterus and vagina, is largely unknown. We applied a multifaceted genetic approach to studying the pathogenesis of MRKH including exome sequencing of trios and duos, genome sequencing of families, qPCR, RT-PCR, and Sanger sequencing to detect intragenic deletions, insertions, splice variants, single nucleotide variants, and rearrangements in 132 persons with MRKH. We identified two heterozygous variants in ZNHIT3 localized to a commonly involved CNV region at chromosome 17q12 in two different families with MRKH. One is a frameshift, truncating variant that is predicted to interfere with steroid hormone binding of the LxxLL sequence of the C-terminal region. The second variant is a double missense/stopgain variant. Both variants impair protein expression in vitro. In addition, four more probands with MRKH harbored the stopgain variant without the nearby missense variant. In total, 6/132 (4.5%) of patients studied, including five with associated anomalies (type 2 MRKH), had ZNHIT3 variants that impair function in vitro. Our findings implicate ZNHIT3 as an important gene associated with MRKH within the 17q12 CNV region.

Disruption of H3K36 methylation provokes cellular plasticity to drive aberrant glandular formation and squamous carcinogenesis.

Chromatin organization is essential for maintaining cell-fate trajectories and developmental programs. Here, we find that disruption of H3K36 methylation dramatically impairs normal epithelial differentiation and development, which promotes increased cellular plasticity and enrichment of alternative cell fates. Specifically, we observe a striking increase in the aberrant generation of excessive epithelial glandular tissues, including hypertrophic salivary, sebaceous, and meibomian glands, as well as enhanced squamous tumorigenesis. These phenotypic and gene expression manifestations are associated with loss of H3K36me2 and rewiring of repressive H3K27me3, changes we also observe in human patients with glandular hyperplasia. Collectively, these results have identified a critical role for H3K36 methylation in both in vivo epithelial cell-fate decisions and the prevention of squamous carcinogenesis and suggest that H3K36 methylation modulation may offer new avenues for the treatment of numerous common disorders driven by altered glandular function, which collectively affect large segments of the human population.

Mettl3-catalyzed m6A regulates histone modifier and modification expression in self-renewing somatic tissue.

N6-methyladenosine (m6A) is the most abundant modification on messenger RNAs (mRNAs) and is catalyzed by methyltransferase-like protein 3 (Mettl3). To understand the role of m6A in a self-renewing somatic tissue, we deleted Mettl3 in epidermal progenitors in vivo. Mice lacking Mettl3 demonstrate marked features of dysfunctional development and self-renewal, including a loss of hair follicle morphogenesis and impaired cell adhesion and polarity associated with oral ulcerations. We show that Mettl3 promotes the m6A-mediated degradation of mRNAs encoding critical histone modifying enzymes. Depletion of Mettl3 results in the loss of m6A on these mRNAs and increases their expression and associated modifications, resulting in widespread gene expression abnormalities that mirror the gross phenotypic abnormalities. Collectively, these results have identified an additional layer of gene regulation within epithelial tissues, revealing an essential role for m6A in the regulation of chromatin modifiers, and underscoring a critical role for Mettl3-catalyzed m6A in proper epithelial development and self-renewal.

Methyltransferases in the Pathogenesis of Keratinocyte Cancers.

Recent evidence suggests that the disruption of gene expression by alterations in DNA, RNA, and histone methylation may be critical contributors to the pathogenesis of keratinocyte cancers (KCs), made up of basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (cSCC), which collectively outnumber all other human cancers combined. While it is clear that methylation modifiers are frequently dysregulated in KCs, the underlying molecular and mechanistic changes are only beginning to be understood. Intriguingly, it has recently emerged that there is extensive cross-talk amongst these distinct methylation processes. Here, we summarize and synthesize the latest findings in this space and highlight how these discoveries may uncover novel therapeutic approaches for these ubiquitous cancers.

LSD1 Inhibition Promotes Epithelial Differentiation through Derepression of Fate-Determining Transcription Factors.

Self-renewing somatic tissues depend upon the proper balance of chromatin-modifying enzymes to coordinate progenitor cell maintenance and differentiation, disruption of which can promote carcinogenesis. As a result, drugs targeting the epigenome hold significant therapeutic potential. The histone demethylase, LSD1 (KDM1A), is overexpressed in numerous cancers, including epithelial cancers; however, its role in the skin is virtually unknown. Here we show that LSD1 directly represses master epithelial transcription factors that promote differentiation. LSD1 inhibitors block both LSD1 binding to chromatin and its catalytic activity, driving significant increases in H3K4 methylation and gene transcription of these fate-determining transcription factors. This leads to both premature epidermal differentiation and the repression of squamous cell carcinoma. Together these data highlight both LSD1's role in maintaining the epidermal progenitor state and the potential of LSD1 inhibitors for the treatment of keratinocyte cancers, which collectively outnumber all other cancers combined.

JAK/STAT signaling pathway gene expression is reduced following Nelf knockdown in GnRH neurons.

Hypothalamic gonadotropin releasing hormone (GnRH) is crucial for the proper function of the hypothalamic-pituitary-gonadal (HPG) axis, subsequent puberty, and reproduction. When GnRH neuron migration or GnRH regulation is impaired, hypogonadotropic hypogonadism results. Mutations in the gene for nasal embryonic luteinizing hormone-releasing factor (NELF) have been identified in GnRH-deficient humans. NELF is a predominantly nuclear protein that may participate in gene transcription, but the genes NELF regulates are unknown. To address this question, RNA was extracted from NLT GnRH neuronal cells following either stable Nelf knockdown or scrambled control and subjected to cDNA arrays. Transcription factors and cell migration gene expression was altered most commonly. Members of the Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway, including Stat1, Stat2, Stat5a, Jak2, Irf7 and Irf9, were significantly down regulated as assessed by RT-qPCR. Protein levels of STAT1, phospho-STAT1, and JAK2 were reduced, but the protein level of phospho-JAK2 was not. These findings suggest a role for NELF in the regulation of the JAK/STAT signaling pathway, which have important functions in GnRH neurons.

NELF knockout is associated with impaired pubertal development and subfertility.

Puberty and reproduction require proper signaling of the hypothalamic-pituitary-gonadal axis controlled by gonadotropin-releasing hormone (GnRH) neurons, which arise in the olfactory placode region and migrate along olfactory axons to the hypothalamus. Factors adversely affecting GnRH neuron specification, migration, and function lead to delayed puberty and infertility. Nasal embryonic luteinizing hormone-releasing factor (NELF) is a predominantly nuclear protein. NELF mutations have been demonstrated in patients with hypogonadotropic hypogonadism, but biallelic mutations are rare and heterozygous NELF mutations typically co-exist with mutations in another gene. Our previous studies in immortalized GnRH neurons supported a role for NELF in GnRH neuron migration. To better understand the physiology of NELF, a homozygous Nelf knockout (KO) mouse model was generated. Our findings indicate that female Nelf KO mice have delayed vaginal opening but no delay in time to first estrus, decreased uterine weight, and reduced GnRH neuron number. In contrast, male mice were normal at puberty. Both sexes of mice had impaired fertility manifested as reduced mean litter size. These data support that NELF has important reproductive functions. The milder than expected phenotype of KO mice also recapitulates the human phenotype since heterozygous NELF mutations usually require an additional mutation in a second gene to result in hypogonadotropic hypogonadism.

Comparison of the Microsatellite and Single Nucleotide Polymorphism Methods for Discriminating among Hanwoo (Korean Native Cattle), Imported, and Crossbred Beef in Korea.

The identity of 45 Hanwo and 47 imported beef (non-Hanwoo) samples from USA and Australia were verified using the microsatellite (MS) marker and single nucleotide polymorphism (SNP) methods. Samples were collected from 19 supermarkets located in the city of Seoul and Gyeonggi province, South Korea, from 2009 to 2011. As a result, we obtained a 100% concordance rate between the MS and SNP methods for identifying Hanwoo and non-Hanwoo beef. The MS method presented a 95% higher individual discriminating value for Hanwoo (97.8%) than for non-Hanwoo (61.7%) beef. For further comparison of the MS and SNP methods, blood samples were collected and tested from 54 Hanwoo × Holstein crossbred cattle (first, second, and third generations). By using the SNP and MS methods, we correctly identified all of the first-generation crossbred cattle as non-Hanwoo; in addition, among the second and third generation crossbreds, the ratio identified as Hanwoo was 20% and 10%, respectively. The MS method used in our study provides more information, but requires sophisticated techniques during each experimental process. By contrast, the SNP method is simple and has a lower error rate. Our results suggest that the MS and SNP methods are useful for discriminating Hanwoo from non-Hanwoo breeds.

Differential expression of nasal embryonic LHRH factor (NELF) variants in immortalized GnRH neuronal cell lines.

NELF, a protein identified in migratory GnRH neurons, is predominantly nuclear and alternatively spliced. However, specific NELF splice variants expressed in immortalized GnRH neuronal cell lines from mouse and human are not known. RNA from migratory (GN11 and NLT) and postmigratory (GT1-7) cells in mouse, and (FNCB4-hTERT) cells in human was subjected to RT-PCR. RT-PCR products were cloned, electrophoresed on denaturing gradient gels and sequenced. In addition, quantitative RT-PCR was performed using variant-specific primers. Western blot and immunofluorescence using confocal microscopy were performed for selected variants. Nelf variant 2 (v2), which contains a nuclear localization signal (NLS), was the predominant variant in all mouse and human GnRH neurons. Variants without a NLS (v3 in mouse; v4 in human) were identified. In mouse, v2 protein expression was nuclear, while v3 was non-nuclear. In mouse GnRH neurons, six Nelf splice variant transcripts were identified, including three previously unreported variants. In human, four NELF variant transcripts were observed. In both mouse and human, nuclear and non-nuclear variant transcript and protein were identified, explaining variable NELF cellular localization.

Hepatoprotective and free radical scavenging activities of prenylflavonoids, coumarin, and stilbene from Morus alba.

Chemical investigation of the EtOH extract of Morus alba L. (Moraceae), as guided by free radical scavenging activity, furnished 5,7-dihydroxycoumarin 7-methyl ether (1), two prenylflavones, cudraflavone B (2) and cudraflavone C (3), and oxyresveratrol (4). Compounds 1 and 4 showed superoxide scavenging effects with the IC(50) values of 19.1 +/- 3.6 and 3.81 +/- 0.5 microM, respectively. Compound 4 exhibited a DPPH free radical scavenging effect (IC(50) = 23.4 +/- 1.5 microM). Compounds 2 and 4 showed hepatoprotective effects with EC(50) values of 10.3 +/- 0.42 and 32.3 +/- 2.62 micro, respectively, on tacrine-induced cytotoxicity in human liver-derived Hep G2 cells.