Biology subjects

Pramanik, T.

Publications and source records attributed to Pramanik, T..

5 recordsLinked to original sources

bioRxiv2026

Functional divergence of WWC family proteins in human endothelial cells

The Hippo signaling pathway is increasingly recognized as a key regulator of endothelial cell (EC) proliferation, migration and vascular development. However, the roles of its upstream scaffold proteins remain poorly understood. Although WWC family proteins are widely regarded as functionally redundant activators of LATS1/2 kinases, the human genome contains a third family member, WWC3, that is absent from mice, raising the possibility of species-specific regulation of endothelial Hippo signaling. Here, we assessed the roles of WWC2 and WWC3 in human ECs using siRNA-mediated knockdown. Surprisingly, we found that WWC3 is the predominant regulator of canonical Hippo signaling, with a substantially greater effect than WWC2 on LATS1/2 phosphorylation, YAP/TAZ localization and expression of Hippo target genes. Loss of WWC3 also altered endothelial morphology and induced a partial endothelial-to-mesenchymal transition-like (EndoMT-like) phenotype. By contrast, WWC2 had a lesser effect on canonical Hippo signaling, but it was required for normal VEGF signaling dynamics. Despite these distinct molecular functions, depletion of either WWC2 or WWC3 impaired EC proliferation, migration, and cord formation in vitro. Together, our findings demonstrate that WWC family proteins perform overlapping but distinct functions in human ECs, with WWC3 acting as the predominant canonical Hippo regulator, whereas WWC2 more efficiently modulates VEGF signaling. These results reveal unexpected functional specialization among WWC proteins and suggest that regulation of Hippo signaling in human ECs differs from that inferred from mouse studies.

cell biology↗

bioRxiv2026

Transient architecture of the embryonic pancreas determines endocrine mass

During organogenesis, epithelial tissues undergo extensive three-dimensional (3D) remodeling while simultaneously generating specialized cell types. Whether these transient architectural states actively instruct lineage allocation remains unclear. Here we identify a morphogenetic stage in which resolution of epithelial stratification is required for lineage allocation and establishment of endocrine cell mass. We show that loss of the Hippo pathway regulator Merlin disrupts lumen morphogenesis and prevents formation of the transient 3D epithelial architecture that characterizes normal pancreas development. Failure to establish this architectural state alters lineage allocation, impairing acinar differentiation, markedly reducing adult endocrine cell mass, and disrupting glucose homeostasis. Mosaic analyses reveal that these lineage defects arise non-cell autonomously, demonstrating that epithelial architecture itself instructs cell fate decisions. Mechanistically, Merlin coordinates PI3K-regulated polarized membrane trafficking required for apical membrane biogenesis and lumen formation. Together, these findings identify Merlin-dependent membrane trafficking as a mechanism coupling epithelial morphogenesis to lineage allocation and demonstrate that transient developmental architectures can determine the cellular composition of mature organs.

developmental biology↗

bioRxiv2026

Endothelial adaptation to complex flow patterns in a novel in vitro model predicted by computational fluid dynamics

The endothelial cells (ECs) that line blood vessels continuously sense and respond to the physical forces exerted by blood flow. In vivo, pulsatile arterial flow interacts with vessel curvature, branching and other anatomical features to generate complex local hemodynamic environments that dictate the magnitude, direction, pulsatility, and oscillatory nature of wall shear stress experienced by ECs. Currently, accessible and reproducible in vitro models of complex pulsatile flow that recapitulate in vivo vascular anatomy remain limited. Here, we combine a novel rotational-flow endothelial culture platform with detailed computational fluid dynamics (CFD) modeling to characterize four well geometries designed to generate distinct hemodynamic environments. CFD analyses demonstrate that these geometries intrinsically generate pulsatile flow and produce reproducible spatially distinct regions of wall shear stress magnitude, pulsatility, and oscillatory shear within a single culture well. Endothelial alignment mapping and functional assays reveal region-specific cellular responses to the predicted local flow conditions that closely corresponded to the predicted local hemodynamic environment, linking complex flow patterns to endothelial adaptation. The technical advancements of our modeling efforts should support a faster, cheaper, simpler, and--importantly--validated framework for future investigation into EC mechanobiology under complex flow conditions. HIGHLIGHTSO_LISimple engineered well geometries generate distinct hemodynamic microenvironments, mimicking in vivo vascular structures, using a conventional orbital shaker. C_LIO_LIComputational fluid dynamics (CFD) reveals spatially distinct patterns of wall shear stress, pulsatility, and oscillatory shear applied to ECs within individual culture wells. C_LIO_LIHigh average wall shear stress and elevated oscillatory shear index induces a unique perpendicular alignment of ECs to the dominant flow vector. C_LI

cell biology↗

bioRxiv2024

Lats1/2 are essential for developmental vascular remodeling and biomechanical adaptation to shear stress

Blood vessels in mammalian embryos develop from initial aggregates of endothelial cell (EC) progenitors, which coordinate the opening and stabilization of central vascular lumens, all while under progressively increasing flow and pressure from blood circulation. Mechanical cues exerted by shear stress from the blood flow remodel an initial vascular plexus into a ramifying array of large and small vessels. As plasma starts to fill vascular lumens, these forces trigger changes in EC gene expression and dynamic alterations in cell shape and cell adhesion, as cuboidal angioblasts elongate and flatten into ECs. Little is known about how embryonic ECs sense and transduce hemodynamic signals as vessels form in vivo. Here, we report a critical requirement for the Lats1 and Lats2 Hippo pathway kinases during this process. We show that when Lats1/2 are genetically deleted in ECs, embryos develop severe defects in blood vessel formation, which lead to embryonic lethality by E11.5. We find that initial vessel patterning and circulation initiate properly, however remodeling of the initial vascular plexus fails due to lumen collapse and altered blood flow. When Lats1/2 are knocked down using siRNA approaches in cultured ECs, cells fail to elongate and polarize, similar to ECs in the mutant embryos. In addition, VE-cadherin (VEcad) based junctions fail to mature under shear stress. These data show that Lats1/2 deficient cells no longer respond to laminar shear stress, both in vivo and in vitro. This work identifies the Hippo pathway kinases Lats1 and Lats2 as critical transducers of biomechanical cues during the early steps of blood vessel remodeling. This study will provide new targets for treatment of vascular diseases and new directions for efforts to generate vascularized tissues for replacement therapies. HighlightsO_LILats1 and Lats2 mRNA and protein are expressed in murine embryonic endothelial cells (ECs). C_LIO_LIDeletion of Lats1/2 in embryonic endothelium results in severe vascular defects and embryonic lethality. C_LIO_LILoss of Lats1/2 leads to failure of both vascular remodeling and EC elongation upon exposure to flow, in vivo and in vitro. C_LIO_LILats1/2 are required for cell-cell VE-cadherin adhesion maturation under flow. C_LIO_LILoss of Lats1/2 results in cytoskeletal disorganization in response to shear stress. C_LI

developmental biology↗

bioRxiv2020

An early cortical progenitor-specific mechanism regulates thalamocortical innervation

The cortical subplate is critical in regulating the entry of thalamocortical sensory afferents into the cortex. These afferents reach the subplate at embryonic day (E)15.5 in the mouse, but "wait" for several days, entering the cortical plate postnatally. We report that when transcription factor Lhx2 is lost in E11.5 cortical progenitors, which give rise to subplate neurons, thalamocortical afferents display premature, exuberant innervation of the E15.5 cortex. Embryonic mutant subplate neurons are correctly positioned below the cortical plate, but they display an altered transcriptome and immature electrophysiological properties during the waiting period. The sensory thalamus in these cortex-specific Lhx2 mutants displays atrophy, eventually leading to severe deficits in thalamocortical innervation. Strikingly, these phenotypes do not manifest if Lhx2 is lost in postmitotic subplate neurons. These results demonstrate a mechanism operating in subplate progenitors that has profound consequences on the growth of thalamocortical axons into the cortex.

neuroscience↗