PPARγ Controls Ectopic Adipogenesis and Cross-Talks with Myogenesis During Skeletal Muscle Regeneration.

Skeletal muscle is a regenerative tissue which can repair damaged myofibers through the activation of tissue-resident muscle stem cells (MuSCs). Many muscle diseases with impaired regeneration cause excessive adipose tissue accumulation in muscle, alter the myogenic fate of MuSCs, and deregulate the cross-talk between MuSCs and fibro/adipogenic progenitors (FAPs), a bi-potent cell population which supports myogenesis and controls intra-muscular fibrosis and adipocyte formation. In order to better characterize the interaction between adipogenesis and myogenesis, we studied muscle regeneration and MuSC function in whole body <i>Pparg</i> null mice generated by epiblast-specific Cre/lox deletion ( <i>Pparg <sup>Δ/Δ</sup></i> ). We demonstrate that deletion of PPARγ completely abolishes ectopic muscle adipogenesis during regeneration and impairs MuSC expansion and myogenesis after injury. Ex vivo assays revealed that perturbed myogenesis in <i>Pparg <sup>Δ/Δ</sup></i> mice does not primarily result from intrinsic defects of MuSCs or from perturbed myogenic support from FAPs. The immune transition from a pro- to anti-inflammatory MuSC niche during regeneration is perturbed in <i>Pparg <sup>Δ/Δ</sup></i> mice and suggests that PPARγ signaling in macrophages can interact with ectopic adipogenesis and influence muscle regeneration. Altogether, our study demonstrates that a PPARγ-dependent adipogenic response regulates muscle fat infiltration during regeneration and that PPARγ is required for MuSC function and efficient muscle repair

Nuclear Proteomics Uncovers Diurnal Regulatory Landscapes in Mouse Liver.

Diurnal oscillations of gene expression controlled by the circadian clock and its connected feeding rhythm enable organisms to coordinate their physiologies with daily environmental cycles. While available techniques yielded crucial insights into regulation at the transcriptional level, much less is known about temporally controlled functions within the nucleus and their regulation at the protein level. Here, we quantified the temporal nuclear accumulation of proteins and phosphoproteins from mouse liver by SILAC proteomics. We identified around 5,000 nuclear proteins, over 500 of which showed a diurnal accumulation. Parallel analysis of the nuclear phosphoproteome enabled the inference of the temporal activity of kinases accounting for rhythmic phosphorylation. Many identified rhythmic proteins were parts of nuclear complexes involved in transcriptional regulation, ribosome biogenesis, DNA repair, and the cell cycle and its potentially associated diurnal rhythm of hepatocyte polyploidy. Taken together, these findings provide unprecedented insights into the diurnal regulatory landscape of the mouse liver nucleus

MIXED LYMPHOCYTE CULTURE TYPING REVISITED: THE STRENGTH OF PROLIFERATIVE ALLORESPONSES TO HLA-DP REFLECTS THE PRESENCE OR ABSENCE OF NON-PERMISSIVE T CELL EPITOPE GROUP MISMATCHES

Transplantation and autoimmunit

Early angiogenic response to shock waves in a three dimensional model of human microvascular endothelial cells culture (HMEC-1)

The exact nature of unfocused shock wave (uSW) action is not, as yet, fully understood, although a possible hypothesis may be that shock waves induce proliferation of endothelial cells and neoangiogenesis. To test this hypothesis, a three dimensional (3D) culture model on Matrigel was developed employing an human microvascular endothelial cell line (HMEC-1) which was stimulated with low energy uSW generated by a lithotripter machine. After 12 hours we observed a statistically significant increase in capillary connections subsequent to shock wave treatment with respect to the control group and a marked 3-hours down-regulation in genes involved in the apoptotic processes (BAX, BCL2LI, GADD45A, PRKCA), in cell cycle (CDKN2C, CEBPB, HK2, IRF1, PRKCA), oncogenes (JUN, WNT1), cell adhesion (ICAM-1), and proteolytic systems (CTSD, KLK2, MMP10). Our preliminary results indicate that endothelial cells in vitro quickly respond to SW, proliferating and forming vessel-like structures, depending on the energy level employed and the number of shocks released. The early decreased expression in the analysed genes could be interpreted as the \u201cfirst reactive response\u201d of the endothelial cells to the external stimuli and the prelude to the events characterizing the neo-angiogenic sequence

Prognostic value of donor cytotoxic T-lymphocyte precursor frequencies for acute graft-versus-host disease in hematopoietic stem cell transplantation from HLA-matched siblings: A single center experience in a cohort of 92 patients

We investigated the prognostic value of cytotoxic T-lymphocyte precursor frequencies (CTL-p-f) for the development of graft-versus-host disease (GvHD) in a cohort of 92 recipients of a hematopoietic stem cell transplantation from HLA-matched sibling donors. CTL-p-f and clinical variables were correlated with acute GvHD and chronic GvHD in univariate and multivariate analyses. CTL-p-f resulted an independent risk factor for severe acute GvHD. Moreover, a trend towards a correlation between CTL-p-f and chronic GvHD was observed. In summary CTL-p-f may be considered as a functional assay useful for identifying patients at high risk of severe GVHD. ©2006 Ferrata Storti Foundation

Mineral and Amino Acid Profiling of Different Hematopoietic Populations from the Mouse Bone Marrow.

Steady hematopoiesis is essential for lifelong production of all mature blood cells. Hematopoietic stem and progenitor cells (HSPCs) found in the bone marrow ensure hematopoietic homeostasis in an organism. Failure of this complex process, which involves a fine balance of self-renewal and differentiation fates, often result in severe hematological conditions such as leukemia and lymphoma. Several molecular and metabolic programs, internal or in close interaction with the bone marrow niche, have been identified as important regulators of HSPC function. More recently, nutrient sensing pathways have emerged as important modulators of HSC homing, dormancy, and function in the bone marrow. Here we describe a method for reliable measurement of various amino acids and minerals in different rare bone marrow (BM) populations, namely HSPCs. We found that the amino acid profile of the most primitive hematopoietic compartments (KLS) did not differ significantly from the one of their direct progenies (common myeloid progenitor CMP), while granulocyte-monocyte progenitors (GMPs), on the opposite of megakaryocyte-erythroid progenitors (MEPs), have higher content of the majority of amino acids analyzed. Additionally, we identified intermediates of the urea cycle to be differentially expressed in the KLS population and were found to lower mitochondrial membrane potential, an established readout on self-renewal capability. Moreover, we were able to profile for the first time 12 different minerals and detect differences in elemental contents between different HSPC compartments. Importantly, essential dietary trace elements, such as iron and molybdenum, were found to be enriched in granulocyte-monocyte progenitors (GMPs). We envision this amino acid and mineral profiling will allow identification of novel metabolic and nutrient sensing pathways important in HSPC fate regulation

ENHANCED ALLOREACTIVITY TO BI-DIRECTIONAL NON-PERMISSIVE HLA-DPB1 MISMATCHES SUPPORTS NON-HIERARCHICAL T-CELL EPITOPE GROUP DIVERSITY AS UNDERLYING BIOLOGICAL MECHANISM

Transplantation and autoimmunit