Here it is shown that the phenotype of adult mice lacking the first enhancer (DNA hypersensitive site I) and the distal promoter of the GATA-1 gene (neoΔHS or GATA-1low mutants) reveals defects in mast cell development. These include the presence of morphologically abnormal alcian blue+ mast cells and apoptotic metachromatic− mast cell precursors in connective tissues and peritoneal lavage and numerous (60–70% of all the progenitors) “unique” trilineage cells committed to erythroid, megakaryocytic, and mast pathways in the bone marrow and spleen. These abnormalities, which were mirrored by impaired mast differentiation in vitro, were reversed by retroviral-mediated expression of GATA-1 cDNA. These data indicate an essential role for GATA-1 in mast cell differentiation.

Deletion of megakaryocytic-specific regulatory sequences of GATA-1 (Gata1 tm2Sho or GATA-1 low mutation) results in severe thrombocytopenia, because of defective thrombocytopoiesis, and myelofibrosis. As documented here, the GATA-1 low mutation blocks megakaryocytic maturation between stage I and II, resulting in accumulation of defective megakaryocytes (MKs) in the tissues of GATA-1 low mice. The block in maturation includes failure to properly organize ␣ granules because von Willebrand factor is barely detectable in mutant MKs, and P-selectin, although normally expressed, is found frequently associated with the demarcation membrane system (DMS) instead of within granules. Conversely, both von Willebrand factor and P-selectin are barely detectable in GATA-1 low platelets. IntroductionMegakaryocytes (MKs) are specialized cells of the blood responsible for platelet production. 1 They originate from committed progenitor cells, usually localized in the marrow, through a complex maturation process, during which MK precursors progressively increase in size, while undergoing extensive synchronous morphologic changes in the cytoplasm and nucleus. 2 At the ultrastructural level, the major cytoplasmic modifications are represented by massive compartmentalization into discrete regions, delimited by intrusions of the plasma membranes, bound to give rise to the demarcation membrane system (DMS). 2 The DMS will, in turn, internalize platelet-specific ␣ granules, giving rise to proplatelets through a process defined thrombocytopoiesis. 3 In the meantime, chromosomes undergo several cycles of endo-duplications. As a result, the nucleus itself appears multilobed.Despite few differences, the morphologic changes associated with the maturation of MK precursors are similar between mice and humans. 4 On the basis of distinct ultrastructural characteristics, murine and human MK precursors are divided into 4 classes 2 : the promegakaryoblast, a small mononuclear cell expressing already platelet-specific proteins, such as von Willebrand Factor (VWF); the megakaryoblast (or stage I MK), a cell 15 to 50 m in diameter with a large, oval or kidney-shaped nucleus and several nucleoli, whose cytoplasm presents abundant ribosomes and a welldeveloped rough endoplasmic reticulum (RER); the promegakaryocyte (stage II MK), a cell 20 to 80 m in diameter with an irregularly shaped nucleus and a more abundant cytoplasm, containing a rudimental DMS; and, finally, mature megakaryocytes (stage III MKs) that contain a multilobed nucleus surrounded by abundant cytoplasm divided into a perinuclear (hosting the centrioles, few biosynthetically active organelles, and many ␣ granules), the intermediate (containing a well-developed DMS and platelet territories), and the peripheral (devoid of organelles and enriched of cytoskeletal proteins and microtubules) zone. 2 The complex process of MK maturation is controlled by lineagespecific extrinsic and intrinsic factors represented, respectively, by growth factors (such as thrombopoietin 5 [TPO]) and transcriptio...

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Endometriosis and urinary calculosis can co-occur. Clinical studies have shown that both painful and non-painful endometriosis in women are associated with enhanced pain and referred muscle hyperalgesia from urinary calculosis, but the mechanisms underlying this phenomenon are still poorly understood. The aim of this study was to develop an animal model adequate to explore this viscero-visceral interaction in standardized conditions. Using a model of endometriosis previously developed to study reduced fertility and vaginal hyperalgesia, endometriosis (endo) or sham-endometriosis (sham-endo) was induced in rats by autotransplantation of small pieces of uterus (or, for sham-endo, fat) on cascade mesenteric arteries, ovary, and abdominal wall. After the endometrial, but not the fat autografts had produced fluid-filled cysts (3 weeks), urinary calculosis was induced by implanting an artificial stone into one ureter. Pain behaviors were monitored by continuous 24-h videotape recordings before and after stone implantation. Referred muscle hyperalgesia was assessed by measuring vocalization thresholds to electrical stimulation of the oblique musculature (L1 dermatome). The data were compared with previously reported data from rats that had received only the stone. Neither endo nor sham-endo alone induced pain behaviors. Following stone implantation, in endo rats compared to sham-endo and stone-only rats, pain behaviors specifically associated with urinary calculosis were significantly increased and new pain behaviors specifically associated with uterine pathology became evident. Muscle hyperalgesia was also significantly increased. To explore the relationship between the amount of endometriosis and that of ureteral pain behavior, two separate groups of endo rats were treated with either a standard non-steroidal anti-inflammatory drugs (ketoprofen) or placebo from the 12th to the 18th day after endometriosis induction. The stone was implanted on the 21st day. Ketoprofen treatment compared to placebo significantly reduced the size of the cysts and both ureteral and uterine pain behaviors post-stone implantation. The size of the cysts showed a significant linear correlation with the post-stone ureteral pain behaviors. In conclusion, endo increased pain crises and muscle hyperalgesia typically induced by a ureteral calculosis, and the ureteral calculosis revealed additional pain behaviors typically induced by uterine pathophysiology; and this enhancement was a function of the degree of endometriosis. This result closely reproduces the condition observed in humans and could be due to a phenomenon of 'viscero-visceral' hyperalgesia, in which increased input from the cyst implantation sites to common spinal cord segments (T10-L1) facilitates the central effect of input from the urinary tract.