Force patterning drives quasistratification and graded tissue-scale spatial order in auditory epithelia Julian Weninger, Anubhav Prakash, Sukanya Raman, Raj K. Ladher, Madan Rao, Karsten Kruse Proceedings of the National Academy of Sciences of the United States of America, 2026 During development, coordinated cell behaviors drive epithelial morphogenesis toward precise three-dimensional architectures essential for physiological function. How such coordination arises in epithelia composed of multiple cell types remains unclear. Here, we study development of the avian auditory epithelium comprising sensory hair cells (HCs) and nonsensory supporting cells (SCs). Initially, HCs and SCs are arranged into mosaics by Notch–Delta signaling. As development proceeds, HCs partially extrude from the epithelium, establish a tenfold gradient in apical surface area across the tissue, and rearrange with SCs to form near-hexagonal order. Using experiments combined with a three-dimensional vertex model, we show that increased contractility at apical junctions between SCs relative to HC–SC junctions drives spatial organization both within the epithelial plane and along the apical–basal axis. Consistent with experimental findings, our simulation shows systematic differences in HC apical area expansion generate opposing coordinated movements of HCs and SCs, establishing gradients in HC apical surface area and density while maintaining uniform hexagonal order. Together, these results demonstrate that spatial patterning of junctional contractility coordinates cell behavior across both the plane and depth of a mixed epithelium, producing quasi-stratified architecture and tissue-scale three-dimensional order.
Junctional force patterning drives both positional order and planar polarity in the auditory epithelia Anubhav Prakash, Julian Weninger, Nishant Singh, Sukanya Raman, Madan Rao, Karsten Kruse, Raj K. Ladher Nature Communications, 2025 Tissue function depends on the precise organisation of the constituent cells. In the cochlea, the fidelity of hearing depends on mechanosensory hair cells being consistently surrounded by supporting cells. In addition to this positional order, auditory sensitivity depends crucially on planar cell polarity. This is characterised by the alignment of the orientation of eccentrically placed hair bundles on each hair cell. These two levels of order emerge simultaneously despite the cellular fluxes that occur during cochlear development. However, the link between tissue-scale cellular rearrangements and intrinsic cellular mechanisms remains unknown. By combining experimental and theoretical approaches, we find a precise force patterning underpinning positional order and planar cell polarity. This occurs through the modulation of the levels and phospho-type of the regulatory light chain of non-muscle myosin II at specific cell-cell junctions of the auditory epithelium. We propose that the control of junctional mechanics is vital for the organisation of multi-cell-type epithelia. Sound is sensed in the cochlea through a precisely organised epithelium. Prakash and colleagues show cellular organisation results from differences in junction contractility, finding mechanics is sufficient to organise a hair cell mosaic that is planar polarised.
Timing of Delamination of Inner Ear Neurons Specifies Their Topography and Target Innervation Surjit Singh Saini, Raj K. Ladher Journal of Comparative Neurology, 2025 The neurons of the inner ear delaminate from a sensorineurogenic epithelium in the ventral part of the otocyst. Delaminated neuroblasts then condense to form the acoustico‐vestibular ganglion (AVG). As they differentiate, the neurons connect mechanosensory hair cells (HCs) of the inner ear with their targets in the hindbrain in a precise topographical manner. However, it is unclear how or when positional identities of neurons are specified within the AVG, such that topographical information from HCs is maintained into the auditory centers of the brain. Here, we find that the time of delamination from the otocyst correlates with neuroblast position in the ganglion. Using markers for neuronal differentiation, we find that the ganglion differentiates from a dorsal to ventral wave. Neurons that differentiate first innervate the vestibular apparatus, including the lagena and the proximal regions of the BP. Using sequential somatic cell labeling, we find that the central projection also follows a similar dependency on delamination order. Our studies show that the time of delamination of otic neuroblasts presages their target innervation choice and fiber positions within the developing eighth cranial nerve. We suggest that temporal information specifies the spatial identities during early inner ear neuron development.
Epithelial fusion is mediated by a partial epithelial–mesenchymal transition Varsha N. Tamilkumar, Harsha Purushothama, Raj K. Ladher Biology Open, 2025 Epithelial fusion is a fundamental morphogenetic process critical for the closure and compartmentalisation of developing organs. While widely studied in systems such as neural tube and palatal closure, the cellular transitions that enable fusion remain poorly understood. Here, we investigate epithelial fusion during chick otic vesicle closure and identify a transient population of cells at the epithelial interface that mediate this process. These otic epithelial edge (OE) cells exhibit distinct morphology, reduced apicobasal polarity, and dynamic junctional remodelling, including altered distribution of ZO-1, CDH1 and RAC1. Notably, OE cells lack basal contact and display high sphericity, consistent with a partial epithelial-to-mesenchymal transition (EMT) phenotype. Transcriptomic profiling of microdissected tissues reveals that OE cells constitute a transcriptionally distinct population, enriched for EMT regulators, extracellular matrix remodelling genes, and WNT pathway components. Among these, the transcription factors Grhl2 and Sp8 were specifically expressed at the OE and exhibited opposing roles in epithelial identity. CRISPR–Cas9-mediated knockdown of either gene led to disrupted CDH1 localisation, loss of OE cell morphology and failure in epithelial segregation. These results suggest that epithelial fusion requires a regulated, hybrid EMT state that balances junctional plasticity with tissue cohesion. Our findings demonstrate that fusion-competent epithelial cells are not merely passive participants but actively modulate their shape, polarity, adhesion and genetic identity to enable morphogenesis.
Coupling between spatial compartments integrates morphogenetic patterning in the organ of Corti Anubhav Prakash, Sukanya Raman, Raman Kaushik, Pallavi Manchanda, Anton S. Iyer, Raj K. Ladher Plos Biology, 2025 Morphogenetic information arises from a combination of genetically encoded cellular properties and emergent cellular behaviors. The spatio-temporal implementation of this information is critical to ensure robust, reproducible tissue shapes, yet the principles underlying its organization remain unknown. We investigated this principle using the mouse auditory epithelium, the organ of Corti (OC). OC consists of a sensory domain, which transduces sound through polar mechanosensory hair cells (HC), part of a mosaic with supporting cells (SC). On either side of the sensory domain are non-sensory domains. These domains undergo cellular rearrangements, which, together, lead to a spiral cochlea that contains planar polarized HCs. This makes the mammalian cochlea a compelling system to understand coordination across spatial scales. Using genetic and ex vivo approaches, we found patterning of OC into sensory and non-sensory domains is associated with a combinatorial expression of adhesion molecules, which underpins OC into spatially defined compartments, enabling planar cell polarity (PCP) cues to regulate compartment-specific organization. Through compartment-specific knockouts of the PCP protein, Vangl2, we find evidence of compartment coupling, a non-linear influence on the organization within one compartment when cellular organization is disrupted in another. In the OC, compartment coupling originates from vinculin-dependent junctional mechanics, coordinating cellular dynamics across spatial scales.
Role of Pcdh15 in the development of intrinsic polarity of inner ear hair cells Raman Kaushik, Shivangi Pandey, Anubhav Prakash, Fenil Ganatra, Takaya Abe, Hiroshi Kiyonari, Raj K. Ladher Plos Genetics, 2025 In vertebrates, auditory information is transduced in the cochlea by mechanosensory hair cells (HC) through an eccentrically organised structure known as the hair bundle. This consists of a true cilium, known as the kinocilium, and modified microvilli, known as stereocilia. The hair bundle has a distinct structure with stereocilia organised in graded rows, with the longest abutting the kinocilium. The hair bundles of all HC are aligned to the tissue axis and are planar polarised. Important in the development and physiology of HC are protein bridges consisting of cadherin-23 (CDH23) and protocadherin-15 (PCDH15). These link the tips of stereocilia, where they play a role in mechanotransduction, and between the kinocilia and the stereocilia, where they are involved in development. Both Cdh23 and Pcdh15 mutations result in defects in planar polarity; however, the mechanism through which this defect arises is unclear. Using a novel mutant for the Pcdh15-CD2 isoform, we show that while the initial deflection of the kinocilium occurs, its peripheral migration to register with Gαi is perturbed. Pcdh15-CD2 genetically interacts with Gpsm2, perturbing vestibular function. We find that the earliest expression of PCDH15-CD2 is at the base of the kinocilia, and the defects in morphogenesis occur before the formation of kinocilial links. By re-introducing functional PCDH15-CD2, we show that polarity can be restored. Our data suggest that, in addition to its adhesive role, PCDH15-CD2 has an early role in intrinsic hair cell polarity through a mechanism independent of kinocilial links.
The primary cilium as a gatekeeper of FGFR2 function Raman Kaushik, Raj K. Ladher Journal of Cell Biology, 2025 In this issue, Nita et al. (https://doi.org/10.1083/jcb.202311030) show that the primary cilium regulates FGFR2 signalling through spatial compartmentalization, enabling selective downstream activation. Disruption of ciliary localization in disease-linked FGFR2 variants highlights the role of the cilium as a signalling gatekeeper in development and disease.
Neuroepithelial bodies and terminal bronchioles are niches for distinctive club cells that repair the airways following acute notch inhibition Sai Manoz Lingamallu, Aditya Deshpande, Neenu Joy, Kirthana Ganeshan, Neelanjana Ray, Rajesh Kumar Ladher, Makoto Mark Taketo, Daniel Lafkas, Arjun Guha Cell Reports, 2024 Lower airway club cells (CCs) serve the dual roles of a secretory cell and a stem cell. Here, we probe how the CC fate is regulated. We find that, in response to acute perturbation of Notch signaling, CCs adopt distinct fates. Although the vast majority transdifferentiate into multiciliated cells, a "variant" subpopulation (v-CCs), juxtaposed to neuroepithelial bodies (NEBs; 5%-10%) and located at bronchioalveolar duct junctions (>80%), does not. Instead, v-CCs transition into lineage-ambiguous states but can revert to a CC fate upon restoration of Notch signaling and repopulate the airways with CCs and multiciliated cells. The v-CC response to Notch inhibition is dependent on localized activation of β-catenin in v-CCs. We propose that the CC fate is stabilized by canonical Notch signaling, that airways are susceptible to perturbations to this pathway, and that NEBs/terminal bronchioles comprise niches that modulate CC plasticity via β-catenin activation to facilitate airway repair post Notch inhibition.
Involvement of Frzb-1 in mesenchymal condensation and cartilage differentiation in the chick limb bud International Journal of Developmental Biology, 1999
Xom: A Xenopus homeobox gene that mediates the early effects of BMP-4 Development, 1996
RECENT SCHOLAR PUBLICATIONS
Force patterning drives quasistratification and graded tissue-scale spatial order in auditory epithelia J Weninger, A Prakash, S Raman, RK Ladher, M Rao, K Kruse Proceedings of the National Academy of Sciences 123 (19), e2519341123 , 2026 2026
Developing an institutional publication data archive S Bhattacharyya, BB Mahapatra, D Palakodeti, R Ladher, SP Sane, ... 2026
Transcriptional control of neuronal maintenance by SOX2 during inner ear innervation S Raman, A Dubey, A Prakash, R Kaushik, L Kannan, P Chugh, ... bioRxiv, 2025.12. 06.692710 , 2025 2025
Notch and Wnt signalling interact for proper prosensory and non-sensory domain formation N Ray, SM Lingamallu, A Guha, RK Ladher bioRxiv, 2025.11. 24.690138 , 2025 2025
Junctional Heterogeneity Shapes Epithelial Morphospace A Prakash, R Kaushik, N Singh, A Walvekar, S Saji, RK Ladher bioRxiv, 2025.11. 03.686357 , 2025 2025 Citations: 1
Timing of delamination of inner ear neurons specifies their topography and target innervation SS Saini, RK Ladher Journal of Comparative Neurology 533 (11), e70103 , 2025 2025 Citations: 1
The patterning and proliferation roles of Shh are partitioned on distinct exosomes A Walvekar, S Pandey, SS Kamat, RK Ladher, N Vyas Developmental Biology , 2025 2025 Citations: 3
Epithelial fusion is mediated by a partial epithelial–mesenchymal transition VN Tamilkumar, H Purushothama, RK Ladher Biology open 14 (9), bio062213 , 2025 2025 Citations: 3
Coupling between spatial compartments integrates morphogenetic patterning in the organ of Corti A Prakash, S Raman, R Kaushik, P Manchanda, AS Iyer, RK Ladher PLoS Biology 23 (9), e3003350 , 2025 2025 Citations: 3
Role of Pcdh15 in the development of intrinsic polarity of inner ear hair cells R Kaushik, S Pandey, A Prakash, F Ganatra, T Abe, H Kiyonari, ... PLoS Genetics 21 (8), e1011825 , 2025 2025 Citations: 3
A Novel Mouse Model Reveals a Role for Mitochondria in Early Lineage Specification and Gastrulation M Ahmed, N Gadepalli, G PS, A Badrinarayanan, RK Ladher bioRxiv, 2025.07. 14.664670 , 2025 2025
Force patterning drives cell flows and 3D spatial order in auditory epithelia J Weninger, A Prakash, S Raman, R Ladher, M Rao, K Kruse bioRxiv, 2025.06. 26.661757 , 2025 2025 Citations: 1
The primary cilium as a gatekeeper of FGFR2 function R Kaushik, RK Ladher Journal of Cell Biology 224 (7), e202505022 , 2025 2025
Junctional force patterning drives both positional order and planar polarity in the auditory epithelia A Prakash, J Weninger, N Singh, S Raman, M Rao, K Kruse, RK Ladher Nature Communications 16 (1), 3927 , 2025 2025 Citations: 10
The patterning and proliferation roles of Shh are partitioned on distinct exosomes SS KAMAT, RK Ladher, N Vyas, A Walvekar, S Pandey Elsevier BV , 2025 2025
Mosaic Atoh1 deletion in the chick auditory epithelium reveals a homeostatic mechanism to restore hair cell number N Singh, R Kaushik, A Prakash, SS Saini, S Garg, A Adhikary, RK Ladher Developmental Biology 516, 35-46 , 2024 2024 Citations: 2
Compartment coupling integrates patterning and morphogenetic information during development A Prakash, S Raman, R Kaushik, P Manchanda, AS Iyer, RK Ladher 2024 Citations: 1
Mechanical coupling of compartments drives polarity and patterning of mouse auditory epithelium A Prakash, S Raman, R Kaushik, AS Iyer, RK Ladher bioRxiv, 2024.09. 16.613243 , 2024 2024
Initiation and formation of stereocilia during the development of mouse cochlear hair cells SR Chakravarthy, TS van Zanten, RK Ladher bioRxiv, 2024.03. 23.586377 , 2024 2024 Citations: 3
Building a multi-institutional research ethics and integrity office in India: processes and challenges S Bhattacharyya, BB Mahapatra, D Palakodeti, RK Ladher, SP Sane, ... European Conference on Ethics and Integrity in Academia, 13-24 , 2023 2023 Citations: 2
MOST CITED SCHOLAR PUBLICATIONS
Mechanisms of GDF-5 action during skeletal development PH Francis-West, A Abdelfattah, P Chen, C Allen, J Parish, R Ladher, ... Development 126 (6), 1305-1315 , 1999 1999 Citations: 491
Signalling interactions during facial development P Francis-West, R Ladher, A Barlow, A Graveson Mechanisms of development 75 (1-2), 3-28 , 1998 1998 Citations: 314
Identification of synergistic signals initiating inner ear development RK Ladher, KU Anakwe, AL Gurney, GC Schoenwolf, PH Francis-West Science 290 (5498), 1965-1967 , 2000 2000 Citations: 296
FGF8 initiates inner ear induction in chick and mouse RK Ladher, TJ Wright, AM Moon, SL Mansour, GC Schoenwolf Genes & development 19 (5), 603-613 , 2005 2005 Citations: 238
Cloning and expression of the Wnt antagonists Sfrp-2 and Frzb during chick development RK Ladher, VL Church, S Allen, L Robson, A Abdelfattah, NA Brown, ... Developmental biology 218 (2), 183-198 , 2000 2000 Citations: 202
Progressive restriction of otic fate: the role of FGF and Wnt in resolving inner ear potential S Freter, Y Muta, SS Mak, S Rinkwitz, RK Ladher Oxford University Press for The Company of Biologists Limited 135 (20), 3415 … , 2008 2008 Citations: 185
Xom : a Xenopus homeobox gene that mediates the early effects of BMP-4 R Ladher, TJ Mohun, JC Smith, AM Snape Development 122 (8), 2385-2394 , 1996 1996 Citations: 176
Mouse FGF15 is the ortholog of human and chick FGF19, but is not uniquely required for otic induction TJ Wright, R Ladher, J McWhirter, C Murre, GC Schoenwolf, SL Mansour Developmental biology 269 (1), 264-275 , 2004 2004 Citations: 166
From shared lineage to distinct functions: the development of the inner ear and epibranchial placodes RK Ladher, P O'Neill, J Begbie Development 137 (11), 1777-1785 , 2010 2010 Citations: 163
Expression of chick Barx‐1 and its differential regulation by FGF‐8 and BMP signaling in the maxillary primordia AJ Barlow, JP Bogardi, R Ladher, PH Francis‐West Developmental dynamics: an official publication of the American Association … , 1999 1999 Citations: 155
Comparison of the expression patterns of several fibroblast growth factors during chick gastrulation and neurulation H Karabagli, P Karabagli, RK Ladher, GC Schoenwolf Anatomy and embryology 205 (5), 365-370 , 2002 2002 Citations: 99
FGFR1-Frs2/3 signalling maintains sensory progenitors during inner ear hair cell formation K Ono, T Kita, S Sato, P O'Neill, SS Mak, M Paschaki, M Ito, N Gotoh, ... PLoS genetics 10 (1), e1004118 , 2014 2014 Citations: 85
Embryonic development of the emu, Dromaius novaehollandiae H Nagai, SS Mak, W Weng, Y Nakaya, R Ladher, G Sheng Developmental Dynamics 240 (1), 162-175 , 2011 2011 Citations: 84
Early steps in inner ear development: induction and morphogenesis of the otic placode X Sai, RK Ladher Frontiers in pharmacology 6, 19 , 2015 2015 Citations: 81
The amniote paratympanic organ develops from a previously undiscovered sensory placode P O'neill, SS Mak, B Fritzsch, RK Ladher, CVH Baker Nature communications 3 (1), 1041 , 2012 2012 Citations: 68
Deficient FGF signaling causes optic nerve dysgenesis and ocular coloboma Z Cai, C Tao, H Li, R Ladher, N Gotoh, GS Feng, F Wang, X Zhang Development 140 (13), 2711-2723 , 2013 2013 Citations: 67
Retinoic acid regulates olfactory progenitor cell fate and differentiation M Paschaki, L Cammas, Y Muta, Y Matsuoka, SS Mak, ... Neural development 8 (1), 13 , 2013 2013 Citations: 62
Evolution of a developmental mechanism: species-specific regulation of the cell cycle and the timing of events during craniofacial osteogenesis J Hall, AH Jheon, EL Ealba, BF Eames, KD Butcher, SS Mak, R Ladher, ... Developmental biology 385 (2), 380-395 , 2014 2014 Citations: 61
Junctionally restricted RhoA activity is necessary for apical constriction during phase 2 inner ear placode invagination X Sai, S Yonemura, RK Ladher Developmental biology 394 (2), 206-216 , 2014 2014 Citations: 58
