A novel all-in-one conditional knockout system uncovered an essential role of DDX1 in ribosomal RNA processing.

Generation of conditional knockout (cKO) and various gene-modified cells is laborious and time-consuming. Here, we established an all-in-one cKO system, which enables highly efficient generation of cKO cells and simultaneous gene modifications, including epitope tagging and reporter gene knock-in. We applied this system to mouse embryonic stem cells (ESCs) and generated RNA helicase Ddx1 cKO ESCs. The targeted cells displayed endogenous promoter-driven EGFP and FLAG-tagged DDX1 expression, and they were converted to Ddx1 KO via FLP recombinase. We further established TetFE ESCs, which carried a reverse tetracycline transactivator (rtTA) expression cassette and a tetracycline response element (TRE)-regulated FLPERT2 cassette in the Gt(ROSA26)Sor locus for instant and tightly regulated induction of gene KO. By utilizing TetFE Ddx1F/F ESCs, we isolated highly pure Ddx1F/F and Ddx1-/- ESCs and found that loss of Ddx1 caused rRNA processing defects, thereby activating the ribosome stress-p53 pathway. We also demonstrated cKO of various genes in ESCs and homologous recombination-non-proficient human HT1080 cells. The frequency of cKO clones was remarkably high for both cell types and reached up to 96% when EGFP-positive clones were analyzed. This all-in-one cKO system will be a powerful tool for rapid and precise analyses of gene functions.

[Mecobalamin improved pernicious anemia in an elderly individual with Hashimoto's disease and diabetes mellitus].

A 73-year-old Japanese man with Hashimoto's disease and diabetes mellitus received regular medical checkups for type 2 diabetes care. Blood tests indicated macrocytic anemia (red blood cell count, 279×104 /µL; hemoglobin, 12.2 g/dL; hematocrit, 34.0%; mean corpuscular volume, 121.9 fL). The laboratory data demonstrated a normal folic acid level with a low vitamin B12 level. An endoscopic examination indicated no signs of gastric or intestinal bleeding. Positive results for anti-intrinsic factor antibodies were strongly suggestive of pernicious anemia. The patient refused cobalamin injections to treat the anemia. However, the oral administration of mecobalamin for the treatment of diabetic neuropathy was simultaneously initiated. Subsequently, the anemia gradually improved. Oral mecobalamin was presumably effective for pernicious anemia management. Anemia is frequently observed in elderly patients, and the incidence of pernicious anemia increases with age. Anemia is conventionally treated with cobalamin injections. Currently, the oral administration of mecobalamin is not the typical treatment for anemia. However, as in our case, a few reports have documented positive results following oral mecobalamin treatment. Moreover, oral mecobalamin is a fairly recent, novel, noninvasive mode of treatment, making it ideal for elderly patients, who are generally frail. This case suggests the efficacy of mecobalamin for the treatment of pernicious anemia.

Multiple Gene Transfer and All-In-One Conditional Knockout Systems in Mouse Embryonic Stem Cells for Analysis of Gene Function.

Mouse embryonic stem cells (ESCs) are powerful tools for functional analysis of stem cell-related genes; however, complex gene manipulations, such as locus-targeted introduction of multiple genes and conditional gene knockout conditional knockout, are technically difficult. Here, we review recent advances in technologies aimed at generating cKO clones in ESCs, including two new methods developed in our laboratory: the simultaneous or sequential integration of multiple genes system for introducing an unlimited number of gene cassettes into a specific chromosomal locus using reciprocal recombinases; and the all-in-one cKO system, which enables introduction of an EGFP reporter expression cassette and FLAG-tagged gene of interest under an endogenous promoter. In addition, methods developed in other laboratories, including conventional approaches to establishment of cKO cell clones, inducible Cas9-mediated cKO generation, and cKO assisted by reporter construct, invertible gene-trap cassette, and conditional protein degradation. Finally, we discuss the advantages of each approach, as well as the remaining issues and challenges.

Change of Oral to Topical Corticosteroid Therapy Exacerbated Glucose Tolerance in a Patient with Plaque Psoriasis.

BACKGROUND Psoriasis is known as the most frequent disease treated by long-term topical steroids. It is also known that patients with thick, chronic plaques require the highest potency topical steroids. However, the treatment is limited to up to four weeks due to risk of systemic absorption. CASE REPORT An 80-year-old man was diagnosed with type 2 diabetes 16 years before, and was being administered insulin combined with alpha glucosidase inhibitor. He was diagnosed with plaque psoriasis and his oral steroid treatment was switched to topical steroid treatment due to lack of improvement and poorly controlled blood glucose level. The hypoglycemic events improved after the psoriatic lesions improved. CONCLUSIONS Control of blood glucose level is difficult at the very beginning of topical steroid treatment for psoriasis especially if a patient is receiving insulin treatment. Intense monitoring of blood glucose level during initiation of topical steroid treatment is necessary to prevent unfavorable complications.