Endothelial and circulating C19MC microRNAs are biomarkers of infantile hemangioma

Infantile hemangioma (IH) is the most common vascular tumor of infancy, and it uniquely regresses in response to oral propranolol. MicroRNAs (miRNAs) have emerged as key regulators of vascular development and are dysregulated in many disease processes, but the role of miRNAs in IH growth has not been investigated. We report expression of C19MC, a primate-specific megacluster of miRNAs expressed in placenta with rare expression in postnatal tissues, in glucose transporter 1-expressing (GLUT-1-expressing) IH endothelial cells and in the plasma of children with IH. Tissue or circulating C19MC miRNAs were not detectable in patients having 9 other types of vascular anomalies or unaffected children, identifying C19MC miRNAs as the first circulating biomarkers of IH. Levels of circulating C19MC miRNAs correlated with IH tumor size and propranolol treatment response, and IH tissue from children treated with propranolol or from children with partially involuted tumors contained lower levels of C19MC miRNAs than untreated, proliferative tumors, implicating C19MC miRNAs as potential drivers of IH pathogenesis. Detection of C19MC miRNAs in the circulation of infants with IH may provide a specific and noninvasive means of IH diagnosis and identification of candidates for propranolol therapy as well as a means to monitor treatment response.

Propranolol responsiveness in vascular tumors is not determined by qualitative differences in adrenergic receptors

Propranolol, a beta 1 (ADBR1) and beta 2 (ADBR2) adrenergic receptor blocker, accelerates regression of proliferating infantile hemangiomas (IH-P) while not affecting non-involuting congenital hemangiomas (NICH) and nonproliferating IH (IH-NP). To determine the expression of ADBRs in vascular tumors, immunofluorescent staining and confocal microscopy were employed to determine the in situ cellular distribution of ADBRs in formalin-fixed paraffin-embedded tissue sections of IH-P, IH-NP, and NICH. In situ cellular proliferation, indexed by Ki-67 expression, distinguished IH-P (n = 3) from both IH-NP (n = 3) and NICH (n = 2). In IH-P, IH-NP, and NICH tumor sections, both ADBR1 and ADBR2 were co-localized in both endothelial cells (ECs; GLUT1(+) in IH; CD31+ in NICH) and pericytes (smooth muscle actin). We tentatively conclude that either EC and/or pericytes in IH-P could be target(s) of propranolol. Cell proliferation, but not absence of either class of ADBR, distinguished the propranolol responsive IH-P from the nonresponsive IH-NP and NICH.

Tertiary lymphoid organs in lymphatic malformations

BACKGROUND

Examine lymphatic malformation lymphoid aggregates for the expression of tertiary lymphoid organ markers. Determine how lymphoid aggregate density relates to lymphatic malformation clinical features.

METHODS AND RESULTS

Retrospective cohort study. Tissue and clinical data were reviewed from 29 patients in the Vascular Anomaly Database who represented the spectrum of head and neck lymphatic malformations and had >5 years of follow-up. Archived formalin-fixed, paraffin-embedded lymphatic malformation tissue was immunohistochemically stained with antibodies for tertiary lymphoid organ markers, which included follicular and mature myeloid dendritic cells, high endothelial venules, segregated B and T-cells, lymphatic endothelial cells, and lymphoid homing chemokines (CXCL13, CCL21). Lymphoid aggregate density (count/mm(2)) was quantified by 2 independent, blinded reviewers. Lymphoid aggregate density and lymphatic malformation clinical features were characterized using analysis of variance. Larger lymphatic malformation tissue lymphoid aggregates stained consistently for tertiary lymphoid organ markers. In oral cavity and neck specimens from the same patients (n = 9), there were more tertiary lymphoid organ in oral cavity than in neck specimens (p = 0.0235). In lymphatic malformation neck tissue, de Serres stage 4 lymphatic malformations displayed the highest tertiary lymphoid organ density. No significant association was seen between tertiary lymphoid organ density and other clinical features.

CONCLUSION

This study demonstrates that some lymphoid aggregates within lymphatic malformations represent tertiary lymphoid organs. There was an association between tertiary lymphoid organ density and lymphatic malformation location. Further study is required to define the role of lymphoid neogenesis and tertiary lymphoid organ formation in lymphatic malformation pathogenesis.

Plzf is required in adult male germ cells for stem cell self-renewal

Adult germline stem cells are capable of self-renewal, tissue regeneration and production of large numbers of differentiated progeny. We show here that the classical mouse mutant luxoid affects adult germline stem cell self-renewal. Young homozygous luxoid mutant mice produce limited numbers of normal spermatozoa and then progressively lose their germ line after birth. Transplantation studies showed that germ cells from mutant mice did not colonize recipient testes, suggesting that the defect is intrinsic to the stem cells. We determined that the luxoid mutant contains a nonsense mutation in the gene encoding Plzf, a transcriptional repressor that regulates the epigenetic state of undifferentiated cells, and showed that Plzf is coexpressed with Oct4 in undifferentiated spermatogonia. This is the first gene shown to be required in germ cells for stem cell self-renewal in mammals.

Polyadenylation and U7 snRNP-mediated cleavage: alternative modes of RNA 3' processing in two avian histone H1 genes

The six chicken histone H1 genes have 3'-processing sequences typical of replication-dependent histone genes, which are expressed as poly(A)- mRNAs. However, by Northern analysis of RNA from several adult chicken tissues, as well as from embryonal skeletal muscle in vivo and in vitro, we have observed histone H1 transcripts longer than those predicted on the basis of the published genomic sequences. These RNAs are polyadenylated transcripts of the genes H1.01 and H1.10, which encode the 'c fraction' H1 protein subtypes. Both transcripts contain an internal stem-loop and purine-rich box associated with the 3' processing of poly(A)- histone mRNAs. The 2-kb poly(A)+ H1.01 transcript is present at high steady-state levels in tissues with low rates of DNA synthesis, has a longer half-life than the poly(A)- mRNA from the same gene, and is polyribosomal in embryonal skeletal muscle. The 1-kb poly(A)+ H1.10 RNA is the major H1.10 transcript in adult skeletal muscle. The properties of these RNAs suggest that they may contribute to the relaxed replication dependence of c fraction subtype expression. The polyadenylation signals of both genes are unusual in their association with processed (nonhistone) pseudogene-like elements, an arrangement with possible implications for the mechanism of alternative 3'-end formation in these genes.

Structure of turnip crinkle virus. III. Identification of a unique coat protein dimer

The minor structural protein (p80), found in about one copy per virion in turnip crinkle virus (TCV), is shown by amino acid analysis and peptide mapping to be a covalent dimer of the major coat protein (p40). The covalent linkage occurs near the N termini of the crosslinked chains. These data suggest that TGV and related viruses contain 178 copies of p40 (89 non-covalent dimers) and one copy of p80 (covalent dimer of two additional p40 chains). The presence of p80 in the salt-stable RNA-protein complex formed when TCV dissociates, as described in an accompanying paper, indicates that the covalent modification affects binding to RNA. We suggest that p80 might be the final dimer to be incorporated into the shell and that it might also be the site for initiation of uncoating.