Palmoplantar keratodermas (PPKs) are a group of disorders that are diagnostically and therapeutically problematic in dermatogenetics1-3. Punctate PPKs are characterized by circumscribed hyperkeratotic lesions on palms and soles with considerable heterogeneity. In 18 families with autosomal dominant punctate PPK (OMIM #148600), we report heterozygous loss-of-function mutations in AAGAB, encoding alpha- and gamma-adaptin binding protein p34, at a previously linked locus on 15q22. p34, a cytosolic protein with a Rab-like GTPase domain, was shown to bind both clathrin adaptor protein complexes, indicative of a role in membrane traffic. Ultrastucturally, lesional epidermis showed abnormalities in intracellular vesicle biology. Immunohistochemistry showed hyperproliferation within the punctate lesions. Knockdown of p34 in keratinocytes led to increased cell division, which was linked to greatly increased epidermal growth factor receptor (EGFR) protein expression and tyrosine phosphorylation. We hypothesize that p34 deficiency may impair endocytic recycling of growth factor receptors such as EGFR, leading to increased signaling and proliferation.

In the early stages of human papillomavirus (HPV) infection, the viral proteins elicit specific immune responses that can participate to regression of ano-genital lesions. HPV E6 protein for instance can reduce type I interferon (IFN) including IFN-κ that is involved in immune evasion and HPV persistence. To evaluate the role of E2 protein in innate immunity in HPV16-associated cervical lesions, genome-wide expression profiling of human primary keratinocytes (HPK) transduced by HPV16 E2 was investigated using microarrays and innate immunity associated genes were specifically analyzed. The analyses showed that the expression of 779 genes was modulated by HPV16E2 and 92 of them were genes associated with innate immunity. Notably IFN-κ and STING were suppressed in HPK expressing the E2 proteins of HPV16 or HPV18 and the trans-activation amino-terminal domain of E2 was involved in the suppressive effect. The relationship between STING, IFN-κ and interferon stimulated genes (ISGs) in HPK was confirmed by gene silencing and real time PCR. The expression of STING and IFN-κ were further determined in clinical specimens by real time PCR. STING and IFN-κ were down-modulated in HPV positive low grade squamous intraepithelial lesions compared with HPV negative controls. This study demonstrates that E2 proteins of high risk HPV reduce STING and IFN-κ transcription and its downstream target genes that might be an immune evasion mechanism involved in HPV persistence and cervical cancer development.

The WHIM syndrome, which features high susceptibility to human papillomavirus (HPV) infection, is a rare immunodeficiency associated with autosomal dominant heterozygous mutations of the CXCR4 chemokine receptor. CXCL12 and its receptors, CXCR4 and CXCR7, are linked to tumorigenesis, and we reported that abnormal expression of CXCL12 in epidermal keratinocytes correlates with HPV infection. However, the HPV-related pathologies observed in WHIM patients remain mechanistically unexplained. We show that keratinocytes immortalized by oncogenic HPV16 or HPV18 upregulate CXCL12 and its receptors in a manner dependent upon expression of the viral proteins E6 and E7. Autocrine signaling activated by CXCL12-engagement of its receptors controls motility and survival of the infected cells. Strikingly, expression of a WHIM syndrome-related gain-of-function CXCR4 mutant confers transforming capacity to HPV18-immortalized keratinocytes. These results establish a pivotal role for CXCL12 signaling in HPV-mediated transformation and provide a mechanistic basis for understanding HPV pathogenesis in WHIM syndrome.