Heterozygous midnolin knockout attenuates severity of nonalcoholic fatty liver disease in mice fed a Western-style diet high in fat, cholesterol, and fructose.

Although midnolin has been studied for over 20 years, its biological roles in vivo remain largely unknown, especially due to the lack of a functional animal model. Indeed, given our recent discovery that the knockdown of midnolin suppresses liver cancer cell tumorigenicity and that this antitumorigenic effect is associated with modulation of lipid metabolism, we hypothesized that knockout of midnolin in vivo could potentially protect from nonalcoholic fatty liver disease (NAFLD) which has become the most common cause of chronic liver disease in the Western world. Accordingly, in the present study, we have developed and now report on the first functional global midnolin knockout mouse model.

MicroRNA-26a targets ten eleven translocation enzymes and is regulated during pancreatic cell differentiation.

Ten eleven translocation (TET) enzymes (TET1/TET2/TET3) and thymine DNA glycosylase (TDG) play crucial roles in early embryonic and germ cell development by mediating DNA demethylation. However, the molecular mechanisms that regulate TETs/TDG expression and their role in cellular differentiation, including that of the pancreas, are not known. Here, we report that (i) TET1/2/3 and TDG can be direct targets of the microRNA miR-26a, (ii) murine TETs, especially TET2 and TDG, are down-regulated in islets during postnatal differentiation, whereas miR-26a is up-regulated, (iii) changes in 5-hydroxymethylcytosine accompany changes in TET mRNA levels, (iv) these changes in mRNA and 5-hydroxymethylcytosine are also seen in an in vitro differentiation system initiated with FACS-sorted adult ductal progenitor-like cells, and (v) overexpression of miR-26a in mice increases postnatal islet cell number in vivo and endocrine/acinar colonies in vitro.

Identification of Oct4-activating compounds that enhance reprogramming efficiency.

One of the hurdles for practical application of induced pluripotent stem cells (iPSC) is the low efficiency and slow process of reprogramming. Octamer-binding transcription factor 4 (Oct4) has been shown to be an essential regulator of embryonic stem cell (ESC) pluripotency and key to the reprogramming process. To identify small molecules that enhance reprogramming efficiency, we performed a cell-based high-throughput screening of chemical libraries.

Complete biallelic insulation at the H19/Igf2 imprinting control region position results in fetal growth retardation and perinatal lethality.

Background: The H19/Igf2 imprinting control region (ICR) functions as an insulator exclusively in the unmethylated maternal allele, where enhancer-blocking by CTCF protein prevents the interaction between the Igf2 promoter and the distant enhancers. DNA methylation inhibits CTCF binding in the paternal ICR allele. Two copies of the chicken β-globin insulator (ChβGI)(2) are capable of substituting for the enhancer blocking function of the ICR.

A new model for studying tissue-specific mdr1a gene expression in vivo by live imaging.

Multidrug resistance continues to be a major impediment to successful chemotherapy in cancer patients. One cause of multidrug resistance is enhanced expression of the mdr1 gene, but the precise factors and physiological conditions controlling mdr1 expression are not entirely known. To gain a better understanding of mdr1 transcriptional regulation, we created a unique mouse model that allows noninvasive bioimaging of mdr1 gene expression in vivo and in real time.

Tumor susceptibility of Rassf1a knockout mice.

The human Ras association domain family 1 (RASSF1) gene is located at 3p21.3 in an area that is believed to harbor at least one important tumor suppressor gene. The two major isoforms of RASSF1, RASSF1A and RASSF1C, are distinguished by alternative NH(2)-terminal exons and the two transcripts initiate in two separate CpG islands.

Role of CTCF binding sites in the Igf2/H19 imprinting control region.

A approximately 2.4-kb imprinting control region (ICR) regulates somatic monoallelic expression of the Igf2 and H19 genes. This is achieved through DNA methylation-dependent chromatin insulator and promoter silencing activities on the maternal and paternal chromosomes, respectively.

A Cre/loxP-deleter transgenic line in mouse strain 129S1/SvImJ.

A Cre recombinase expression cassette was inserted into the X-linked Hprt locus by gene targeting in a mouse embryonic stem (ES) cell line isogenic to strain 129S1/SvImJ (129S1), then the transgene was introduced into 129S1 mice through ES cell chimeras. When females hemizygous for this transgene were mated to males carrying a neomycin selection cassette flanked by loxP sites, the cassette was always excised regardless of Cre inheritance and without detectable mosaicism. The usefulness of this "Cre-deleter" transgenic line is in its efficiency and defined genetic status in terms of mouse strain and location of the transgene.

The chicken beta-globin insulator element conveys chromatin boundary activity but not imprinting at the mouse Igf2/H19 domain.

Imprinting of the mouse insulin-like growth factor 2 (Igf2) and H19 genes is regulated by an imprinting control region (ICR). The hypomethylated maternal copy functions as a chromatin insulator through the binding of CTCF and prevents Igf2 activation in cis, while hypermethylation of the paternal copy inactivates insulator function and leads to inactivation of H19 in cis. The specificity of the ICR sequence for mediating imprinting and chromatin insulation was investigated by substituting it for two copies of the chicken beta-globin insulator element, (Ch beta GI)(2), in mice.