The Mediator subunit MED1 is essential for mammary gland development and lactation, whose contribution through direct interaction with estrogen receptors (ERs) is restricted to involvement in pubertal mammary gland development and luminal cell differentiation. Here, we provide evidence that the MED24-containing submodule of Mediator functionally communicates specifically with MED1 in pubertal mammary gland development. Mammary glands from MED1/MED24 double heterozygous knockout mice showed profound retardation in ductal branching during puberty, while single haploinsufficient glands developed normally. DNA synthesis of both luminal and basal cells were impaired in double mutant mice, and the expression of ERtargeted genes encoding E2F1 and cyclin D1, which promote progression through the G 1 /S phase of the cell cycle, was attenuated. Luciferase reporter assays employing double mutant mouse embryonic fibroblasts showed selective impairment in ER functions. Various breast carcinoma cell lines expressed abundant amounts of MED1, MED24, and MED30, and attenuated expression of MED1 and MED24 in breast carcinoma cells led to attenuated DNA synthesis and growth. These results indicate functional communications between the MED1 subunit and the MED24-containing submodule that mediate estrogen receptor functions and growth of both normal mammary epithelial cells and breast carcinoma cells. N uclear receptors, which include steroid and nonsteroid hormone receptors, comprise a superfamily of DNA-bound transcriptional regulators that are activated in response to specific small lipophilic ligands and that play major physiological roles in cell growth, differentiation, and homeostasis (reviewed in references 10 and 25). Estrogen receptor ␣ (ER␣) is the key activator that leads to growth of the mammary glands during adolescence, as well as during pregnancy, in response to elevated plasma estrogen levels. Among the hormone-responsive genes transcribed under the control of ER␣ is another steroid hormone receptor, progesterone receptor (PR), which in concert with ER␣, plays an important role in mammary gland development (5).The metazoan Mediator/TRAP coactivator complex is a master transcriptional coregulator composed of about 30 subunits and is structurally subdivided into head, body, and tail modules. It constitutes a subcomplex of the RNA polymerase II holoenzyme and integrates a wide variety of intracellular signals through specific interactions of activators with specific Mediator subunits that reside predominantly at its tail module (reviewed in references 4, 6, 15, 20, and 24). We have proposed a multistep model for nuclear receptor-induced transcriptional activation (15). In this model, histone-modifying coactivators that possess either histone acetyltransferase or histone methyltransferase activities first interact with ligand-bound nuclear receptors, and chromatin structure is subsequently relaxed. Then an exchange of coactivators takes place and the Mediator is bound to nuclear receptors through two canonical LxxLL nuc...

MED1/TRAP220, a subunit of the transcriptional Mediator/TRAP complex, is crucial for various biological events through its interaction with distinct activators, such as nuclear receptors and GATA family activators. In hematopoiesis, MED1 plays a pivotal role in optimal nuclear receptor-mediated myelomonopoiesis and GATA-1-induced erythropoiesis. In this study, we present evidence that MED1 in stromal cells is involved in supporting hematopoietic stem and/or progenitor cells (HSPCs) through osteopontin (OPN) expression. We found that the proliferation of bone marrow ( The specialized microenvironmental niches in the bone marrow (BM), namely, the osteoblastic (or endosteal) and vascular niches, host and interface with hematopoietic stem cells (HSCs) and are the sites where their size and fate are strictly regulated (15, 29; reviewed in references 1, 16, 28, 30, and 34). HSCs and their niches produce diverse molecules, whose interactions control HSC self-renewal and differentiation. In the osteoblastic niche, almost 75% of the HSCs are in a quiescent (slowly cycling or G 0 ) state. In a physiological condition, HSCs migrate from the osteoblastic niche toward the vascular niche, enter the cell cycle, and undergo symmetric cell division or asymmetric division, accompanied by differentiation and final maturation. In this manner, a defined set of mature differentiated progeny is continuously produced without HSC depletion.The transcriptional Mediator complex, originally isolated as a thyroid hormone receptor-associated protein (TRAP) complex and subsequently identified as a mammalian counterpart of the yeast Mediator complex (i.e., a subcomplex of the RNA polymerase II holoenzyme), appears to serve as a bridge between diverse activators and the general transcriptional machinery (reviewed in references 4, 13, 18, and 21). This complex contains approximately 25 polypeptides, among which the MED1/TRAP220 subunit is responsible for specific binding of the complex to several activators, which include nuclear receptors (13), GATA family members (22, 27), C/EBP␤ (20), and BRCA1 (33). Mediator conveys the specific signals of the activators to the recruited general transcriptional machinery to activate transcription by direct communication between MED1 and the activators (5).Through the interaction with MED1, nuclear receptors are involved in various hematocytic differentiations. For example, the vitamin D receptor (VDR) and retinoic acid receptor (RAR) are members of the nuclear hormone receptor superfamily, whose interaction with MED1 is crucial for liganddependent monopoiesis and granulopoiesis, respectively, as well as for peroxisome proliferator-activated receptor ␥ (PPAR␥)-mediated adipogenesis (7, 31). GATA-1, for which MED1 was recently shown to be a specific coactivator, mediates erythropoiesis through its interaction with MED1 (27). However, as Med1 null mice die early during embryogenesis (12,22), it is difficult to determine the physiological role of MED1 in BM hematopoiesis in vivo.Osteopontin (OPN), an acidic glyc...

The mean myeloperoxidase index (MPXI) is calculated during the routine complete blood count performed using the autoanalyzer ADVIA120/2120. The pattern of changes in the neutrophil myeloperoxidase levels in patients with specific infectious diseases was analyzed by assessing the MPXI levels. In patients with bacterial sepsis, identified by positive blood-culture tests, with (n = 29) and without (n = 51) systemic inflammatory response syndrome, the mean MPXI significantly reduced to -3.18 and -2.06, respectively. In contrast, among patients with nontuberculous nonseptic bacterial infections (n = 40), the mean MPXI significantly elevated to 5.51, while tuberculosis patients (n = 37) and patients with viral infection (n = 60) showed an unchanged MPXI (mean values, -0.46 and -1.06, respectively). Among the parameters of inflammation, only the C-reactive protein values showed a weak correlation with the MPXI levels. [Conclusion] These results indicate that MPXI is correlated with some specific infectious states, i.e. MPXI is low in bacterial sepsis and high in nontuberculous nonseptic bacterial infections. MPXI appears to be an independent and useful biomarker for the diagnosis and follow-up of infectious diseases, especially when the MPXI values are obtained at regular intervals during the disease courses of the patients.

Two closely related casein kinase I (CKI) isoforms, CKI␦ and CKI⑀, are ubiquitously expressed in many human tissues, but their specific biologic function remains to be clarified. Here, we provide the first evidence that CKI⑀ is involved in hematopoietic cell differentiation. CKI⑀, but not CKI␦, was down-regulated along with human granulocytic differentiation. The specific down-regulation was observed in granulocyte colony-stimulating factor (G-CSF)-induced cell differentiation of murine interleukin-3 (IL-3)-dependent myeloid progenitor 32D cells. Introduction of wild-type (WT)- IntroductionMembers of the casein kinase I (CKI) family of monomeric serine/threonine kinases are highly conserved from yeast to human and are ubiquitously expressed in different cell types. 1,2 In mammals, 7 isoforms (␣, ␤, ␥1-3, ␦, and ⑀) have been identified. [3][4][5][6] These isoforms share a high degree of similarity within the NH 2 -terminal catalytic domains but show considerable variation in their carboxy-terminal (C-terminal) noncatalytic domains. Their variable C-terminal domains are responsible for substrate specificity and serve to promote differential subcellular localization of individual isoforms and to modulate kinase activity. 4,[7][8][9][10] Studies of CKI homologs in yeast have shown the biologic role of CKI in the regulation of DNA repair and normal cell cycle progression, vesicular trafficking, and cytokinesis. [11][12][13][14][15] The identification of potential substrates for CKI in vitro also possibly inferred that CKI might be involved in a wide variety of cellular functions in mammals. For example, CKI is likely to regulate DNA and RNA metabolism, cellular morphology, vesicular trafficking, DNA damage response and repair, and the activity of various transmembrane receptors. [16][17][18][19][20][21][22][23][24] From the diverse cellular functions of CKI isoforms arose a possibility that CKI is likely to regulate the stability of their substrates, protein turnover, and transport-dependent cellular processes. [25][26][27][28] However, there have been only a few reports in which the phosphorylation by CKI is shown to be essential for the biologic function of the substrates. Unexpectedly, recent genetic analyses in diverse fields have demonstrated that CKI⑀ plays an essential role in regulating several critical in vivo processes such as circadian rhythm, embryogenesis, and morphogenesis in various species. [29][30][31][32] The homolog of CKI␦ and CKI⑀ was first cloned in a screen for a budding yeast mutant, hrr25. 11 Human CKI␦ and CKI⑀ encoded on 2 independent genes localized at chromosome 17q25 and 22q12-13 are basic polypeptides of 49 kDa and 47 kDa, respectively. 4,5 They are the closest isoforms in the CKI family, because their amino acid sequences are 98% identical over their kinase domains and 53% identical over their C-terminal domains. The autophosphorylation of the C-terminal domain has been shown to inhibit its kinase activity. 33 Successful complementation of hrr25 mutants in budding yeast by human CKI␦ ...

The TRAP220 subunit of the thyroid hormone receptor-associated polypeptide transcription coactivator complex (TRAP/Mediator complex), mammalian counterpart of the yeast Mediator complex, is proposed to act on a variety of major and specific biological events through physical interactions with nuclear receptors. The vitamin D receptor (VDR) and retinoic acid receptor (RAR), coupled with retinoid X receptor (RXR), are nuclear receptors which have important roles for monopoiesis and granulopoiesis, respectively. In this study, we present the functional role of TRAP220 in nuclear receptor-mediated monopoiesis and granulopoiesis. The mouse Trap220 -/-yolk sac hematopoietic progenitor cells were resistant to 1,25-dihydroxyvitamin D 3 -stimulated differentiation into monocytes/macrophages. Furthermore, flow cytometric analyses showed that HL-60 cells, human promyelocytic leukemia cell line, wherein TRAP220 was down-regulated, did not differentiate efficiently into monocytes and granulocytes by stimulation with 1,25-dihydroxyvitamin D 3 and all-trans retinoic acid, correspondingly. The expression of direct target genes of VDR or RAR, as well as the differentiation marker genes, was low in the knockdown cells. These results indicated a crucial role of TRAP220 in the optimal VDR-and RAR-mediated myelomonocytic differentiation processes in mammalian hematopoiesis.