Biology subjects

Prasanna, J.

Publications and source records attributed to Prasanna, J..

3 recordsLinked to original sources

bioRxiv2024

Inhibition of Proteasome Activity Facilitates Definitive Endodermal Specification of pluripotent Stem Cells by influencing YAP signaling

Understanding the molecular players that control the specification of definitive endoderm is imperative to obtain the homogenous population of pancreatic {beta}-cells from stem cells. Though the Ubiquitin proteasome system (UPS) has been envisaged as a crucial intracellular protein degradation system, its role in germ layer specification remains elusive. In this study, using a mouse embryonic stem cells model system (mESCs) we observed decreased proteasomal activity specifically during endoderm, but not in meso- or ecto-derm differentiation. Extraneous inhibition of proteasomal activity during differentiation enhanced the expression of endodermal genes specifically. Enhancing proteasomal activity by including the activator IU1 in the induction culture, inhibited definitive endodermal differentiation. Further, inhibiting proteasomal activity at the definitive endodermal stage resulted in enhanced generation of insulin-positive cells. A similar increase in endodermal gene expression by inhibiting proteasomal activity was observed in miPSC and hiPSC differentiated towards endodermal lineage. Mechanistic insight showed no contribution of endoplasmic reticulum unfolded protein response but revealed the involvement of the YAP signaling pathway in proteasome-inhibited enhanced endodermal differentiation. Unravelling the specific involvement of UPS in endodermal cell fate specification in pluripotent stem cells paves the way for obtaining better qualitative and quantitative definitive endodermal cells for plausible cellular therapy in the future.

cell biology↗

bioRxiv2022

Zic3 enables bimodal regulation of tyrosine hydroxylase expression in dopaminergic neurons of olfactory bulb and midbrain

Dopaminergic (DA) neurons in the Olfactory bulb (OB) are involved in odor detection and discrimination. Transcription factor (TF) regulatory network responsible for their fate specification remains poorly understood and the spatial regulation of DA neurons remains elusive. In this study, mice exposed to odor stimulant exhibited specific upregulation of Zinc finger transcription factor of Cerebellum (ZIC) 3 along with Tyrosine Hydroxylase (TH). Stringent co-expression analysis showed ZIC3 and TH dual positive neurons in OB. Genetic manipulation showed ZIC3 to be both essential and sufficient to drive TH expression and essential for odor perception. ZIC3 interacts with ER81 and binds to region encompassing ER81 binding site in DA neurons and is indispensable for TH expression. In midbrain (MB), in the absence of ER81, ZIC3 switches its molecular partner and binds to Pitx3 promoter-a DA fate determinant. Under ectopic expression of ER81 in MB DA neurons, propensity of ZIC3 binding to Pitx3 promoter is compromised and its occupancy on Th promoter encompassing ER81 binding site is established, finally culminating in desired TH expression. Together, these findings reveal a unique ZIC3 mediated bimodal regulation of TH in OB and MB to ultimately facilitate DAergic fate.

neuroscience↗

bioRxiv2022

Deubiquitinase USP1 influences the dedifferentiation of mouse pancreatic β-cells

Diabetes is a metabolic disease caused majorly due to loss of insulin secreting {beta}-cells. Along with apoptosis, recent reports revealed dedifferentiation to be the added reason for the reduced {beta}-cell mass. The Ubiquitin Proteasome system comprising of E3 ligase and deubiquitinases (DUBs) control several key aspects of pancreatic {beta}-cell functions. The role of deubiquitinases in orchestrating the dedifferentiation process in several cancers have been well deciphered, but its role in dedifferentiation of pancreatic {beta}-cells remains elusive. In this study, screening for key DUBs that regulate dedifferentiation, identified USP1 to be specifically involved in the process. Inhibition of USP1 either by genetic intervention or small molecule inhibitor ML323 restored epithelial phenotype of {beta}-cells, but not with inhibition of other DUBs. Conversely overexpression of USP1 was sufficient to dedifferentiate {beta}-cells, even in absence of dedifferentiation inducing cues. Mechanistic insight showed USP1 to probably mediate its effect via modulating the expression of Inhibitor of Differentiation (ID) 2. Further, in an in vivo streptozotocin (STZ) induced dedifferentiation mouse model system, treatment with ML323 rescued the hyperglycaemic state. Overall, this study assigns a novel role to USP1 in dedifferentiation of {beta}-cells and its inhibition may have a therapeutic application of reducing the {beta}-cell loss during diabetes.

cell biology↗