Citrullination of HP1γ chromodomain affects association with chromatin

BACKGROUND

Stem cell differentiation involves major chromatin reorganisation, heterochromatin formation and genomic relocalisation of structural proteins, including heterochromatin protein 1 gamma (HP1γ). As the principal reader of the repressive histone marks H3K9me2/3, HP1 plays a key role in numerous processes including heterochromatin formation and maintenance.

RESULTS

We find that HP1γ is citrullinated in mouse embryonic stem cells (mESCs) and this diminishes when cells differentiate, indicating that it is a dynamically regulated post-translational modification during stem cell differentiation. Peptidylarginine deiminase 4, a known regulator of pluripotency, citrullinates HP1γ in vitro. This requires R38 and R39 within the HP1γ chromodomain, and the catalytic activity is enhanced by trimethylated H3K9 (H3K9me3) peptides. Mutation of R38 and R39, designed to mimic citrullination, affects HP1γ binding to H3K9me3-containing peptides. Using live-cell single-particle tracking, we demonstrate that R38 and R39 are important for HP1γ binding to chromatin in vivo. Furthermore, their mutation reduces the residence time of HP1γ on chromatin in differentiating mESCs.

CONCLUSION

Citrullination is a novel post-translational modification of the structural heterochromatin protein HP1γ in mESCs that is dynamically regulated during mESC differentiation. The citrullinated residues lie within the HP1γ chromodomain and are important for H3K9me3 binding in vitro and chromatin association in vivo.

Incorporation of Ln-Doped LaPO4 Nanocrystals as Luminescent Markers in Silica Nanoparticles

Lanthanide ions are promising for the labeling of silica nanoparticles with a specific luminescent fingerprint due to their sharp line emission at characteristic wavelengths. With the increasing use of silica nanoparticles in consumer products, it is important to label silica nanoparticles in order to trace the biodistribution, both in the environment and living organisms.In this work, we synthesized LaPO4 nanocrystals (NCs) with sizes ranging from 4 to 8 nm doped with europium or cerium and terbium. After silica growth using an inverse micelle method, monodisperse silica spheres were obtained with a single LaPO4 NC in the center. We demonstrate that the size of the silica spheres can be tuned in the 25-55 nm range by addition of small volumes of methanol during the silica growth reaction. Both the LaPO4 core and silica nanocrystal showed sharp line emission characteristic for europium and terbium providing unique optical labels in silica nanoparticles of variable sizes.

Out-of-pocket expenditures for childbirth in the context of the Janani Suraksha Yojana (JSY) cash transfer program to promote facility births: who pays and how much? Studies from Madhya Pradesh, India

BACKGROUND

High out-of-pocket expenditures (OOPE) make delivery care difficult to access for a large proportion of India's population. Given that home deliveries increase the risk of maternal mortality, in 2005 the Indian Government implemented the Janani Suraksha Yojana (JSY) program to incentivize poor women to deliver in public health facilities by providing a cash transfer upon discharge. We study the OOPE among JSY beneficiaries and women who deliver at home, and predictors of OOPE in two districts of Madhya Pradesh.

METHODS

September 2013 to April 2015 a cross-sectional community-based survey was performed. All recently delivered women were interviewed to elicit delivery costs, socio-demographic characteristics and delivery related information.

RESULTS

Most women (n = 1995, 84 %) delivered in JSY public health facility, the remaining 16 % (n = 386) delivered at home. Women who delivered under JSY program had a higher median, IQR OOPE ($8, 3-18) compared to home ($6, 2-13). Among JSY beneficiaries, poorest women had twice net gain ($20) versus wealthiest ($10) post cash transfer. Informal payments (64 %) and food/baby items (77 %) were the two most common sources of OOPE. OOPE made among JSY beneficiaries was pro-poor: poorer women made proportionally less expenditures compared to wealthier women. In an adjusted model, delivering in a JSY public facility increased odds of incurring expenditures (OR: 1.58, 95 % CI: 1.11-2.25) but at the same time to a 16 % (95 % CI: 0.73-0.96) decrease in the amount paid compared to home deliveries.

CONCLUSIONS

OOPE is prevalent among JSY beneficiaries as well in home deliveries. In JSY, OOPE varies by income quintile: wealthier quintiles pay more OOPE. However the cash incentive is adequate enough to provide a net gain for all quintiles. OOPE was largely due to indirect costs and not direct medical payments. The program seems to be effective in providing financial protection for the most vulnerable groups.