The topical delivery of transgenes to hair follicles has potential for treating disorders of the skin and hair. Here we show that the topical administration of liposome-DNA mixtures (lipoplex) to mouse skin and to human skin xenografts resulted in efficient in vivo transfection of hair follicle cells. Transfection depended on liposome composition, and occurred only at the onset of a new growing stage of the hair cycle. Manipulating the hair follicle cycle with depilation and retinoic acid treatment resulted in nearly 50% transfection efficiency-defined as the proportion of transfected, newly growing follicles within the xenograft. Transgenes administered in this fashion are selectively expressed in hair progenitor cells and therefore have the potential to affect the characteristics of the follicle. These findings form a foundation for the future use of topical lipoplex applications to alter hair follicle phenotype and treat diseases of the hair and skin.
Previous studies indicated that members of the myc gene family may be essential for preimplantation development. Other studies revealed that preimplantation embryos lacking c‐myc, N‐myc, or L‐myc are viable, indicating that these genes are either not essential for preimplantation development or can be substituted for functionally by other myc gene family members. To investigate the possible role of these genes during preimplantation development, we determined the temporal patterns of expression of four members of the myc gene family, genes encoding myc‐associated proteins, and four putative MYC target genes. We observed a sequential pattern of myc gene expression, with the L‐myc mRNA expressed as a maternal transcript, the c‐myc mRNA expressed during the 4‐cell through morula stages, and the B‐myc mRNA expressed highly at the morula and blastocysts stages. B‐myc was the predominant family member expressed during preimplantation development. The mxi mRNA was not detectable and the mad mRNA was detectable only as a maternal transcript. The max mRNA, however, was expressed both as a maternal mRNA and as an embryonic message throughout most of preimplantation development. Three putative MYC target genes (Odc, cyclin E, and prothymosin‐α) were tarnscriptionally induced during the 2‐cell stage, and their mRNAs increased sharply in abundance during development to the morula and blastocyst stages. Another putative MYC target gene, cyclin A, was expressed both as a maternal mRNA and as an embryonic transcript. These data support the view that the expression of myc target genes may be supported initially through the expression of maternally inherited MYC proteins and corresponding mRNAs and that subsequent stage‐specific changes in expression of myc genes, myc‐associated genes, and myc target genes may control early differentiative events around the time of implantation. Mol. Reprod. Dev. 47:57–65, 1997. © 1997 Wiley‐Liss, Inc.
IntroductionThe ability of hematopoietic stem cells (HSCs) to sustain hematopoiesis throughout life involves the coordinated interaction of several genes and signaling pathways, including HoxB4, Notch1, Bmi-1, and Wnts. [1][2][3][4][5][6][7][8][9][10][11] Manipulating the levels of expression of one or more of these genes offers the potential to artificially alter the balance of stem cell proliferation versus differentiation for analytic and therapeutic applications.We previously identified the trimeric transcription factor Nuclear Factor Y (NF-Y) as a regulated activator of HoxB4 transcription, as well as several other genes involved in HSC proliferation, including HoxC4, HoxD4, Notch1, and Lef-1, and suggested that NF-Y is a candidate key regulator of HSC self-renewal. 12 NF-Y is composed of 3 subunits: NF-Ya, NF-Yb, and NF-Yc. NF-Yb and NF-Yc are constitutively expressed in most cells and interact via a histone-fold motif to form heterodimers. When NF-Ya peptide is expressed, trimers form that bind to a subset of CCAAT consensus binding site. [13][14][15][16][17] NF-Y regulates the expression of many genes important in diverse cell types, including the cell cycle control genes cyclin A2, cyclin B1, and cyclin B2, 18 and some erythroidspecific genes 19,20 MDR1 21 and GADD45 ␥. 22 Cellular, molecular, and developmental specificity for NF-Y activity is established through multiple mechanisms. In addition to the regulation of transcription, direct interaction of NF-Y with other transcription factors into larger-order transcription units plays a key role. Probably because of the importance of NF-Y in diverse cellular processes, constitutive deletion of NF-Ya in embryonic stem cells results in early embryonic lethality. 23 NF-Y plays an essential role in hematopoiesis through the regulated expression of NF-Ya. Postnatal deletion of NF-Ya within HSCs leads to a G2M block in HSCs and hematopoieitic progenitor cells, resulting in complete hematopoietic failure. 24 NF-Ya is preferentially expressed in HSCs and declines with their differentiation. Retroviral overexpression of NF-Ya in HSCs activates the transcription of genes implicated in self-renewal and differentiation, including the Hox4 paralogs HoxB4, HoxC4, and HoxD4, as well as Hes-1, LEF1, Notch1, p27, and telomerase, and biases HSCs toward self-renewal rather then differentiation, showing a prominent increase in their in vivo repopulating ability after bone marrow transplantation. 12 Although retroviral expression of NF-Ya is efficient and powerful, its application to clinical therapeutics is problematic because of both the difficulty in controlling the level and duration of expression of the transgene and the potential for insertional leukemogenesis. Dogs and macaques transplanted with primary CD34 ϩ cells transduced by retroviral vector overexpressing HoxB4, developed myeloid leukemia 2 years after transplantation. 25 These results suggest that viral delivery of genes biasing cells to undifferentiated state poses a significant threat of complications.Nonvira...
The proteins synthesized in mouse thymocytes after irradiation and hydrocortisone treatment were analyzed by two-dimensional electrophoresis. An exposure to lympholytic agents induced different changes in the biosynthesis of proteins; however the induction of a few common proteins by these agents was revealed. The increase in the synthesis of five nuclear polypeptides occurred at early times (15-75 min) after irradiation. At least two of them (proteins of the nuclear matrix) are also induced by hydrocortisone. Synthesis of three of these 'early proteins' soon terminated, while the synthesis of the other two increased, and by 3.5 h they were found in large quantities after both treatments. At the same time, another protein common for both agents was induced. Three of these nuclear proteins are part of the nuclear matrix. Participation of these proteins in realization of the cell death program is discussed.
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