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Guhathakurta, S.

Publications and source records attributed to Guhathakurta, S..

3 recordsLinked to original sources

An Efficient Microfluidic Platform for Organ-Specific CyclicMultiaxial Loading and Differentiation of Progenitor Cells

Mechanical loading is a fundamental regulator of tissue development, maturation, and function, yet existing in vitro systems predominantly apply uniaxial load/strain to cell-laden hydrogels, limiting their ability to reproduce physiologically relevant multiaxial on-chip tissue mechanics. Here, we present an engineered system to apply controlled multiaxial mechanical loading to real scaffolds with undifferentiated cells. The system enables programmable cyclic stretching and relaxation at the cell scaffold level and is compatible with both cell-laden native scaffold and engineered soft tissues. We have quantified the strain field experienced by the tissue with distinct mechanical loading periods using computation simulations and validated these with systematic experiments, demonstrating reproducible and various organ-relevant multiaxial strain profiles. As proof of concept, we applied the approach to human cardiac tissues, where cyclic multiaxial mechanical loading of mononuclear cells laden native tissue scaffold promoted cardiac structural organization and supports the emergence of spontaneous contractile activity. This approach provides a generalizable method for reproducing physiologically relevant tissue mechanics in vitro and enables systematic investigation of mechano-regulation across a plethora of human tissues.

bioengineering↗

Acetylation-dependent clustering of BRD2 instructs transcription dynamics

BET protein inhibitors represent one of the most prominent classes of epigenetic drugs. However, the specific contributions of individual BET family members to transcription regulation remain largely unknown. Here, by acutely co-depleting BET proteins, we uncover an essential role of BRD2 in maintaining RNA Polymerase II recruitment at promoters, which becomes especially critical in the absence of BRD4 or when pause release is inhibited. Combining rapid protein degradation, chemogenomics, and super-resolution microscopy, we show that H4 acetylation, particularly H4K16ac, serves as a template for BRD2 function, driving sub-diffraction BRD2 cluster formation at chromatin. Accordingly, depletion of BRD2 or the writer of H4K16ac, MOF decreases sub-diffraction RNA Polymerase II clusters, which are associated with transcription initiation. Thus, this study highlights the importance of acetylated chromatin in transcriptional coactivator organization and the distinct role of BRD2 in transcription initiation dynamics.

genomics↗

Targeted attenuation of elevated histone marks at SNCA alleviates α-synuclein in Parkinson's disease

Epigenetic de-regulation of -synuclein plays a key role in Parkinsons disease (PD). Analysis of the SNCA promoter using the ENCODE database revealed the presence of important histone posttranslational modifications (PTMs) including transcription-promoting marks, H3K4me3 and H3K27ac, and repressive mark, H3K27me3. We investigated these histone marks in postmortem brains of controls and PD patients and observed that only H3K4me3 was significantly elevated at the SNCA promoter of the substantia nigra (SN) of PD patients both in punch biopsy as well as in NeuN positive neuronal nuclei samples. To understand the importance of H3K4me3 in regulation of -synuclein, we developed CRISPR/dCas9-based locus-specific H3K4me3 demethylating system where the catalytic domain of JARID1A was recruited to the SNCA promoter. This CRISPR/dCas9 SunTag-JARID1A significantly reduced H3K4me3 at SNCA promoter and concomitantly decreased -synuclein both in the neuronal cell line SH-SY5Y and idiopathic PD-iPSC derived dopaminergic neurons. In sum, this study indicates that -synuclein expression in PD is controlled by SNCAs histone PTMs and modulation of the histone landscape of SNCA can reduce -synuclein expression.

neuroscience↗