Biology subjects

Lazzerini, E.

Publications and source records attributed to Lazzerini, E..

3 recordsLinked to original sources

bioRxiv2020

CTCF is a Barrier for Totipotent-like Reprogramming

Totipotent cells have the ability of generating embryonic and extra-embryonic tissues1,2. Interestingly, a rare population of cells with totipotent-like potential was identified within ESC cultures3. These cells, known as 2 cell (2C)-like cells, arise from ESC and display similar features to those found in the totipotent 2 cell embryo2-4. However, the molecular determinants of 2C-like conversion have not been completely elucidated. Here, we show that CTCF is a barrier for 2C-like reprogramming. Indeed, forced conversion to a 2C-like state by DUX expression was associated with DNA damage at a subset of CTCF binding sites. Endogenous or DUX-induced 2C-like ESC showed decreased CTCF enrichment at known binding sites, suggesting that acquisition of a totipotent-like state is associated with a highly dynamic chromatin architecture. Accordingly, depletion of CTCF in ESC efficiently promoted spontaneous and asynchronous conversion to a totipotent-like state. This phenotypic reprogramming was reversible upon restoration of CTCF levels. Furthermore, we showed that transcriptional activation of the ZSCAN4 cluster was necessary for successful 2C-like reprogramming. In summary, we revealed the intimate relation between CTCF and totipotent-like reprogramming.

developmental biology↗

bioRxiv2020

Activation of FAM111A Protease Induces Defects in Nuclear Function that Likely Underlie its Roles in Disease and Viral Restriction

Mutations in the nuclear trypsin-like serine protease FAM111A cause Kenny-Caffey syndrome (KCS2) with hypoparathyroidism and skeletal dysplasia, or perinatally lethal osteocraniostenosis (OCS). In addition, FAM111A was identified as a restriction factor for certain host range mutants of the SV40 polyomavirus and VACV orthopoxvirus. However, because FAM111A function is poorly characterized, its roles in restricting viral replication and the etiology of KCS2 and OCS remain undefined. We find that the FAM111A KCS2 and OCS patient mutants are hyperactive, inducing apoptosis-like phenotypes in a protease-dependent manner. Similarly, in response to the attempted replication of SV40 host range mutants in restrictive cells, FAM111A activity induces the loss of nuclear barrier function and structure. Interestingly, pan-caspase inhibitors do not block FAM111A-dependent phenotypes such as nuclear "leakiness", shrinkage and pore redistribution, implying it acts independently or upstream of caspases. In this regard, we identified nucleoporins and the associated GANP transcription factor as FAM111A interactors and candidate targets. Together our data provide key insight into how FAM111A activation can restrict viral replication, and how its deregulated activity could cause KCS2 and OCS.

cell biology↗

bioRxiv2019

Modulation and recruitment of TRF2 at viral telomeres during human herpesvirus 6A/B infection

Human herpesviruses 6A and 6B (HHV-6A/B) can integrate their genomes into the telomeres of host chromosomes. The HHV-6A/B genomes contain telomeric repeats essential for integration. Whether HHV-6A/B infections impact telomere homeostasis remains to be studied. We report that during infection, a massive increase in telomeric signals is observed. Such telomeric signals are detected in viral replication compartments (VRC) that colocalize with the viral IE2 and P41 proteins. Infection with HHV-6A mutants lacking telomeric repeats did not reproduce this phenotype. HHV-6A/B infections lead to increased expression of three shelterin genes, TRF1, TRF2 and TPP1. TRF2 was recruited to VRC and binding to the HHV-6A/B telomeric repeats demonstrated by chromatin immunoprecipitation and ELISA. Lastly, the HHV-6A IE2 protein colocalized with shelterin proteins at telomeres during infection. In summary, HHV-6A/B infections results in an excess of telomeric repeats that stimulates the expression of shelterin genes. TRF2 binds to viral telomeres during infection and localizes with HHV-6A IE2 protein. Our results highlight a potential role for shelterin complex proteins and IE2 during infection and possibly during integration of HHV-6A/B into host chromosomes.

microbiology↗