👤 Karsten Boldt

High-risk human papillomaviruses (HPV), particularly HPV16, are major causes of anogenital and oropharyngeal cancers. The HPV late promoter, P670 in the case of HPV16, is activated upon host cell differentiation and drives the expression of viral capsid proteins. While differentiation-specific host transcription factors have been implicated in regulating this promoter, the mechanism remains incompletely understood. HPV E2 proteins activate transcription by interacting with the host protein BRD4 (Bromodomain-containing protein 4). A biotin proximity ligation screen identified several novel E2 interactors, of which many overlap with the BRD4 interactome, suggesting BRD4 mediates a large fraction of these interactions. One such interactor, ZC3H4 (Zinc finger CCCH domain-containing protein 4), is known to restrict the expression of long non-coding RNAs, including enhancer and promoter upstream antisense RNAs (uaRNAs). E2 recruits ZC3H4 in a BRD4-dependent manner to specifically activate the P670 promoter in reporter assays. Supporting this, E2 and ZC3H4 co-localize in cells with high P670 activity. ZC3H4 is upregulated during differentiation, and its knockdown in differentiated HPV16- or HPV31-positive cells reduces late viral transcripts in an E2-BRD4-dependent manner. Interestingly, knockdown of ZC3H4 does not increase viral uaRNAs, suggesting that ZC3H4 does not enhance HPV late transcription by regulating viral antisense transcription. High-risk human papillomaviruses (HPVs), particularly HPV16, can cause anogenital and oropharyngeal cancers. HPV16 relies on the differentiation-dependent activation of its late promoter, P670, to produce capsid proteins. While host transcription factors contribute to this regulation, the mechanisms remain incompletely defined. Our findings reveal that the viral E2 protein collaborates with the host protein BRD4-a critical transcriptional regulator-to recruit other cellular partners, such as ZC3H4. Normally, ZC3H4 suppresses non-coding RNAs in cells, but HPV16 repurposes it via BRD4 to activate P670. This interaction intensifies in differentiated cells, where ZC3H4 levels rise, and disrupting ZC3H4 specifically blocks late viral gene expression without affecting antisense viral transcription. This highlights a unique, differentiation-dependent strategy HPV16 uses to hijack host machinery for its replication. Show less

Several genome-wide association studies (GWAS) have been carried out with late-onset Alzheimer's disease (LOAD), mainly in European and Asian populations. Different polymorphisms were associated, but several of them without a functional explanation. GWAS are fundamental for identifying loci associated with diseases, although they often do not point to causal polymorphisms. In this sense, functional investigations are a fundamental tool for discovering causality, although the failure of this validation does not necessarily indicate a non-causality. Furthermore, the allele frequency of associated genetic variants may vary widely between populations, requiring replication of these associations in other ethnicities. In this sense, our study sought to replicate in 150 AD patients and 114 elderly controls from the South Brazilian population 18 single-nucleotide polymorphisms (SNPs) associated with AD in European GWAS, with further functional investigation using bioinformatic tools for the associated SNPs. Of the 18 SNPs investigated, only four were associated in our population: rs769449 ( Show less

Microtubule actin crosslinking factor 1 (MACF1) plays a role in the coordination of microtubules and actin in multiple cellular processes. Here, we show that MACF1 is also critical for ciliogenesis in multiple cell types. Ablation of Macf1 in the developing retina abolishes ciliogenesis, and basal bodies fail to dock to ciliary vesicles or migrate apically. Photoreceptor polarity is randomized, while inner retinal cells laminate correctly, suggesting that photoreceptor maturation is guided by polarity cues provided by cilia. Deletion of MACF1 in adult photoreceptors causes reversal of basal body docking and loss of outer segments, reflecting a continuous requirement for MACF1 function. MACF1 also interacts with the ciliary proteins MKKS and TALPID3. We propose that a disruption of trafficking across microtubles to actin filaments underlies the ciliogenesis defect in cells lacking MACF1 and that MKKS and TALPID3 are involved in the coordination of microtubule and actin interactions. Show less