Research articles

Cerebral cavernous malformation (CCM) is a life-threatening disorder in which blood vessels in the brain are prone to hemorrhage. Kevin Whitehead et al. now show that CCM2, mutations in which are associated with CCM, is needed for specific aspects of endothelial cell function involving RhoA GTPase. These defects can be partially restored by statin treatment, suggesting a potential therapeutic intervention for individuals with CCM. The role of CCM2 in the endothelium is also explored in another paper published in this issue of Nature Medicine, by Benjamin Kleaveland et al

Ethylmalonic encephalopathy is an autosomal recessive developmental disorder that is characterized by chronic diarrhea and multiple neurological deficits. It is associated with loss-of-function mutations in the ETHE1 gene. Now, Massimo Zeviani and his colleagues report that ETHE1 is a dioxygenase that is responsible for breaking down toxic sulfide in a variety of organs.

A main function of fat cells is to store fuel for future use, which is released when the fat is broken down in a process called lipolysis. Here Hei Sook Sul and colleagues describe a new enzyme in fat, AdPLA, that inhibits lipolysis and shows that genetic deletion results in protection from obesity in two mouse models.

Studies of hepatitis C virus replication in cell culture have suggested that certain microRNAs are required for efficient virus replication and that they may be involved in the antiviral effect of interferon. A study in humans infected with the virus provides a new perspective.

Identifying factors that influence response to cancer chemotherapy is crucial for improving its efficacy. Mauro Delorenzi and his colleagues report that a stromal gene expression signature predicts resistance to a commonly used chemotherapy regimen in individuals with estrogen receptor–negative breast tumors. These findings underline the potential of the tumor microenvironment to modulate tumor phenotype and the clinical response to treatment.

There is a need for mouse tumor models that more closely recapitulate the pathophysiology of human cancers. Here, a mouse model of glioblastoma multiforme (GBM) is generated with Cre-loxP controlled, lentiviral-mediated delivery of the oncogenes H-Ras and AKT. Transduction of the oncogenes in a small number of cells in adult immunocompetent mice led to the formation of GBM-like tumors, particularly when combined with loss of p53.

The chemokines CCL5 and CXCL4 promote monocyte recruitment to atherosclerotic plaques. Recent findings in vitro have shown that heteromerization of CCL5 and CXCL4 increases their potency in stimulating monocyte adhesion and chemotaxis. Koenen et al. now show that this heteromerization has functional consequences in vivo. Treatment of atherosclerotic mice with a cyclic peptide that specifically disrupts the CCL5-CXCL4 interaction inhibited monocyte recruitment to atherosclerotic plaques. Moreover, selective inhibition of heteromer formation may offer therapeutic advantages compared to complete blockade of chemokine function.