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Summary Conventional strategies are not particularly successful in treatment of leukemia, and identification of signaling pathways crucial to the activity of leukemia stem cells will provide targets for the development of new therapies. Here we report that certain receptors containing the immunoreceptor tyrosine-based inhibition motif (ITIM) are crucial for the development of acute myeloid leukemia (AML). Inhibition of expression of the ITIM-containing receptor LAIR1 does not affect normal hematopoiesis but abolishes leukemia development. LAIR1 induces activation of SHP-1, which acts as a phosphatase-independent signaling adaptor to recruit CAMK1 for activation of downstream CREB in AML cells. The LAIR1/SHP-1/CAMK1/CREB pathway sustains the survival and self-renewal of AML stem cells. Intervention in the signaling initiated by ITIM-containing receptors such as LAIR1 may result in successful treatment of AML.

Duchenne muscular dystrophy (DMD), the most common lethal genetic disorder in children, is an X-linked recessive muscle disease characterized by the absence of dystrophin at the sarcolemma of muscle fibers. We examined a putative endometrial progenitor obtained from endometrial tissue samples to determine whether these cells repair muscular degeneration in a murine mdx model of DMD. Implanted cells conferred human dystrophin in degenerated muscle of immunodeficient mdx mice. We then examined menstrual blood-derived cells to determine whether primarily cultured nontransformed cells also repair dystrophied muscle. In vivo transfer of menstrual blood-derived cells into dystrophic muscles of immunodeficient mdx mice restored sarcolemmal expression of dystrophin. Labeling of implanted cells with enhanced green fluorescent protein and differential staining of human and murine nuclei suggest that human dystrophin expression is due to cell fusion between host myocytes and implanted cells. In vitro analysis revealed that endometrial progenitor cells and menstrual blood-derived cells can efficiently transdifferentiate into myoblasts/myocytes, fuse to C2C12 murine myoblasts by in vitro coculturing, and start to express dystrophin after fusion. These results demonstrate that the endometrial progenitor cells and menstrual blood-derived cells can transfer dystrophin into dystrophied myocytes through cell fusion and transdifferentiation in vitro and in vivo.

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This study focused on the cloning, expression, and characterization of ginsenoside-transforming recombinant β-glucosidase from Actinosynnema mirum KACC 20028(T) in order to biotransform ginsenosides efficiently. The gene, termed as bglAm, encoding a β-glucosidase (BglAm) belonging to the glycoside hydrolase family 3 was cloned. bglAm consisted of 1,830 bp (609 amino acid residues) with a predicted molecular mass of 65,277 Da. This enzyme was overexpressed in Escherichia coli BL21(DE3) using a GST-fused pGEX 4T-1 vector system. The recombinant BglAm was purified with a GST·bind agarose resin and characterized. The optimum conditions of the recombinant BglAm were pH 7.0 and 37 °C. BglAm could hydrolyze the outer and inner glucose moieties at the C3 and C20 of the protopanaxadiol-type ginsenosides (i.e., Rb(1) and Rd, gypenoside XVII) to produce protopanaxadiol via gypenoside LXXV, F(2), and Rh(2)(S) with various pathways. BglAm can effectively transform the ginsenoside Rb(1) to gypenoside XVII and Rd to F(2); the K (m) values of Rb(1) and Rd were 0.69 ± 0.06 and 0.45 ± 0.02 mM, respectively, and the V (max) values were 16.13 ± 0.29 and 51.56 ± 1.35 μmol min(-1) mg(-1) of protein, respectively. Furthermore, BglAm could convert the protopanaxatriol-type ginsenoside Re and Rg(1) into Rg(2)(S) and Rh(1)(S) hydrolyzing the attached glucose moiety at the C6 and C20 positions, respectively. These various ginsenoside-hydrolyzing pathways of BglAm may assist in producing the minor ginsenosides from abundant major ginsenosides.