Most human coronaviruses cause mild upper respiratory tract disease but may be associated with more severe pulmonary disease in immunocompromised individuals. However, SARS coronavirus caused severe lower respiratory disease with nearly 10% mortality and evidence of systemic spread. Recently, another coronavirus (human coronavirus-Erasmus Medical Center (hCoV-EMC)) was identified in patients with severe and sometimes lethal lower respiratory tract infection. Viral genome analysis revealed close relatedness to coronaviruses found in bats. Here we identify dipeptidyl peptidase 4 (DPP4; also known as CD26) as a functional receptor for hCoV-EMC. DPP4 specifically co-purified with the receptor-binding S1 domain of the hCoV-EMC spike protein from lysates of susceptible Huh-7 cells. Antibodies directed against DPP4 inhibited hCoV-EMC infection of primary human bronchial epithelial cells and Huh-7 cells. Expression of human and bat (Pipistrellus pipistrellus) DPP4 in non-susceptible COS-7 cells enabled infection by hCoV-EMC. The use of the evolutionarily conserved DPP4 protein from different species as a functional receptor provides clues about the host range potential of hCoV-EMC. In addition, it will contribute critically to our understanding of the pathogenesis and epidemiology of this emerging human coronavirus, and may facilitate the development of intervention strategies.

The HMG-box transcription factor Sox2 plays a role throughout neurogenesis and also acts at other stages of development, as illustrated by the multiple organs affected in the anophthalmia syndrome caused by SOX2 mutations. Here we combined proteomic and genomic approaches to characterize gene regulation by Sox2 in neural stem cells. Chd7, a chromatin remodeling ATPase associated with CHARGE syndrome, was identified as a Sox2 transcriptional cofactor. Sox2 and Chd7 physically interact, have overlapping genome-wide binding sites and regulate a set of common target genes including Jag1, Gli3 and Mycn, genes mutated in Alagille, Pallister-Hall and Feingold syndromes, which show malformations also associated with SOX2 anophthalmia syndrome or CHARGE syndrome. Regulation of disease-associated genes by a Sox2-Chd7 complex provides a plausible explanation for several malformations associated with SOX2 anophthalmia syndrome or CHARGE syndrome. Indeed, we found that Chd7-haploinsufficient embryos showed severely reduced expression of Jag1 in the developing inner ear.

Transcription-coupled nucleotide-excision repair (TC-NER) is a subpathway of NER that efficiently removes the highly toxic RNA polymerase II blocking lesions in DNA. Defective TC-NER gives rise to the human disorders Cockayne syndrome and UV-sensitive syndrome (UV(S)S). NER initiating factors are known to be regulated by ubiquitination. Using a SILAC-based proteomic approach, we identified UVSSA (formerly known as KIAA1530) as part of a UV-induced ubiquitinated protein complex. Knockdown of UVSSA resulted in TC-NER deficiency. UVSSA was found to be the causative gene for UV(S)S, an unresolved NER deficiency disorder. The UVSSA protein interacts with elongating RNA polymerase II, localizes specifically to UV-induced lesions, resides in chromatin-associated TC-NER complexes and is implicated in stabilizing the TC-NER master organizing protein ERCC6 (also known as CSB) by delivering the deubiquitinating enzyme USP7 to TC-NER complexes. Together, these findings indicate that UVSSA-USP7–mediated stabilization of ERCC6 represents a critical regulatory mechanism of TC-NER in restoring gene expression.

Abstract-Tissue accumulation of circulating prorenin results in angiotensin generation, but could also, through binding to the recently cloned (pro)renin receptor, lead to angiotensin-independent effects, like p42/p44 mitogen-activated protein kinase (MAPK) activation and plasminogen-activator inhibitor (PAI)-1 release. Here we investigated whether prorenin exerts angiotensin-independent effects in neonatal rat cardiomyocytes. Polyclonal antibodies detected the (pro)renin receptor in these cells. Prorenin affected neither p42/p44 MAPK nor PAI-1. PAI-1 release did occur during coincubation with angiotensinogen, suggesting that this effect is angiotensin mediated. Prorenin concentrationdependently activated p38 MAPK and simultaneously phosphorylated HSP27. The latter phosphorylation was blocked by the p38 MAPK inhibitor SB203580. Rat microarray gene (nϭ4800) transcription profiling of myocytes stimulated with prorenin detected 260 regulated genes (PϽ0.001 versus control), among which genes downstream of p38 MAPK and HSP27 involved in actin filament dynamics and (cis-)regulated genes confined in blood pressure and diabetes QTL regions, like Syntaxin-7, were overrepresented. Quantitative real-time RT-PCR of 7 selected genes (Opg, Timp1, Best5, Hsp27, Col3a1, and Hk2) revealed temporal regulation, with peak levels occurring after 4 hours of prorenin exposure. This regulation was not altered in the presence of the renin inhibitor aliskiren or the angiotensin II type 1 receptor antagonist eprosartan. Finally, pilot 2D proteomic differential display experiments revealed actin cytoskeleton changes in cardiomyocytes after 48 hours of prorenin stimulation. In conclusion, prorenin exerts angiotensinindependent effects in cardiomyocytes. Prorenin-induced stimulation of the p38 MAPK/HSP27 pathway, resulting in alterations in actin filament dynamics, may underlie the severe cardiac hypertrophy that has been described previously in rats with hepatic prorenin overexpression. (Hypertension. 2006;48:564-571.)