Abstract-The epicardium plays an essential role in coronary artery formation and myocardial development, but signals controlling the development and differentiation of this tissue are not well understood. To investigate the role of platelet-derived growth factor receptor (PDGFR)␤ in development of epicardial-derived vascular smooth muscle cells (VSMCs), we examined PDGFR␤ Ϫ/Ϫ and PDGFR␤ epicardial mutant hearts. We found that PDGFR␤ Ϫ/Ϫ hearts failed to form dominant coronary vessels on the ventral heart surface, had a thinned myocardium, and completely lacked coronary VSMCs (cVSMCs). This constellation of defects was consistent with a primary defect in the epicardium. To verify that these defects were specific to epicardial derivatives, we generated mice with an epicardial deletion of PDGFR␤ that resulted in reduced cVSMCs distal to the aorta. The regional absence of cVSMCs suggested that cVSMCs could arise from 2 sources, epicardial and nonepicardial, and that both were dependent on PDGFR␤. In the absence of PDGFR␤ signaling, epicardial cells adopted an irregular actin cytoskeleton, leading to aberrant migration of epicardial cells into the myocardium in vivo. In addition, PDGF receptor stimulation promoted epicardial cell migration, and PDGFR␤-driven phosphoinositide 3Ј-kinase signaling was critical for this process. Our data demonstrate that PDGFR␤ is required for the formation of 2 distinct cVSMC populations and that loss of PDGFR␤-PI3K signaling disrupts epicardial cell migration. , and past data have demonstrated that many coronary VSMCs (cVSMCs) are derived from the embryonic epicardium. 2,3 Whereas several genes have been identified that are essential for the formation, attachment, and spreading of the epicardium, few genes have been identified that are essential during epithelial-to-mesenchymal transition (EMT) and subsequent differentiation into cVSMCs and cardiac fibroblasts.Platelet-derived growth factor receptor (PDGFR) tyrosine kinases are 1 family of signaling proteins that are potentially involved in epicardial cell function. Analyses in the mouse have shown that PDGFR␤ signaling promotes proliferation and migration of VSMCs in multiple vascular beds including the heart. 4 -8 Therefore, we investigated the function of PDGFR␤ signaling during epicardial development. We have examined PDGFR␤ Ϫ/Ϫ , epicardial-specific PDGFR␤ mutant, and PDGFR␤ signaling-deficient embryos. We discovered that epicardial deletion resulted in the absence of cVSMCs distal to the aorta and that PDGFR␤ signaling through phosphoinositide 3Ј-kinase (PI3K) was required for proper cytoskeletal organization in epicardial cells. Our results designate PDGF receptor signaling as another growth factor system involved in epicardial development.

Mucins are being implicated in diagnosis, prognosis, and as therapeutic targets due to their aberrant expression in a variety of carcinomas. Here, we have analyzed the expression of MUC4 and have compared its potential usefulness in early detection and prognosis of ovarian carcinoma alone and in combination with other mucin antigens, MUC1 and MUC16. Clinical significance of the differential mucin expression was evaluated by grouping the tumor samples in early (stage I and II) and advanced (stage III and IV) stage cases and histological subtypes (serous, mucinous, endometrioid and clear cell). Correlation of these mucins with patient's survival (n ¼ 63) was determined by Kaplan-Meier analysis in order to predict their prognostic value. MUC4 showed significant overexpression in tumor cases (Po0.0001) with highest incidence (92.0%) among all three mucins. A significant overexpression of MUC1 (Po0.018) and MUC16 (Po0.0001) was also observed in 83.0 and 79.0% of tumor samples, respectively. Notably, MUC4 expression was significantly higher (Pr0.004) compared to both MUC1 and MUC16 in early-stage ovarian tumor samples with 100% incidence. In advanced stage ovarian tumors, all the mucins displayed overall comparable expression, nonetheless, MUC4 had highest prevalence (88.0%) compared to MUC1 (84.0%) and MUC16 (81.0%). A combined panel of MUC4 with MUC16 detected 100% of the late-stage tumor cases without compromising the specificity. Among histological subtypes, only MUC4 displayed 100% (n ¼ 5) sensitivity in mucinous ovarian tumors, while MUC1 and MUC16 detected 40 and 20% cases, respectively. The expression of MUC4, however, did not significantly correlate with the survival of the ovarian cancer patient, while a significant correlation of MUC16 with poor prognosis was observed. In conclusion, our study demonstrates that MUC4 could be a potential candidate marker for early diagnosis of epithelial ovarian carcinoma and can be utilized in combination with MUC16 to achieve greater sensitivity for the detection of late-stage tumors.

Bosch-Boonstra-Schaaf optic atrophy syndrome (BBSOAS) has been identified as an autosomal-dominant disorder characterized by a complex neurological phenotype, with high prevalence of intellectual disability and optic nerve atrophy/hypoplasia. The syndrome is caused by loss-of-function mutations in NR2F1, which encodes a highly conserved nuclear receptor that serves as a transcriptional regulator. Previous investigations to understand the protein’s role in neurodevelopment have mostly used mouse models with constitutive and tissue-specific homozygous knockout of Nr2f1. In order to represent the human disease more accurately, which is caused by heterozygous NR2F1 mutations, we investigated a heterozygous knockout mouse model and found that this model recapitulates some of the neurological phenotypes of BBSOAS, including altered learning/memory, hearing defects, neonatal hypotonia and decreased hippocampal volume. The mice showed altered fear memory, and further electrophysiological investigation in hippocampal slices revealed significantly reduced long-term potentiation and long-term depression. These results suggest that a deficit or alteration in hippocampal synaptic plasticity may contribute to the intellectual disability frequently seen in BBSOAS. RNA-sequencing (RNA-Seq) analysis revealed significant differential gene expression in the adult Nr2f1+/− hippocampus, including the up-regulation of multiple matrix metalloproteases, which are known to be critical for the development and the plasticity of the nervous system. Taken together, our studies highlight the important role of Nr2f1 in neurodevelopment. The discovery of impaired hippocampal synaptic plasticity in the heterozygous mouse model sheds light on the pathophysiology of altered memory and cognitive function in BBSOAS.

No abstract