Search bioRxiv⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2023.02.07.527523

Planarian LDB and SSDP proteins scaffold transcriptional complexes for regeneration and patterning

Medlock-Lanier, T.·Clay, K. B.·Roberts-Galbraith, R. H.
View original source ↗Export metadata ↓

Abstract

Sequence-specific transcription factors often function as components of large regulatory complexes. LIM-domain binding protein (LDB) and single-stranded DNA-binding protein (SSDP) function as core scaffolds of transcriptional complexes in animals and plants. Little is known about potential partners and functions for LDB/SSDP complexes in the context of tissue regeneration. In this work, we find that planarian LDB1 and SSDP2 promote tissue regeneration, with a particular function in mediolateral polarity reestablishment. We find that LDB1 and SSDP2 interact with one another and with characterized planarian LIM-HD proteins Arrowhead, Islet1, and Lhx1/5-1. SSDP2 and LDB1 also function with islet1 in polarity reestablishment and with lhx1/5-1 in serotonergic neuron maturation. Finally, we show new roles for LDB1 and SSDP2 in regulating gene expression in the planarian intestine and parenchyma; these functions may be LIM-HD-independent. Together, our work provides insight into LDB/SSDP complexes in a highly regenerative organism. Further, our work provides a strong starting point for identifying and characterizing potential binding partners of LDB1 and SSDP2 and for exploring roles for these proteins in diverse aspects of planarian physiology.

Source connections

Explore related subjects

developmental biologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Medlock-Lanier, T., Clay, K. B., Roberts-Galbraith, R. H.. 2023-02-08. Planarian LDB and SSDP proteins scaffold transcriptional complexes for regeneration and patterning. https://doi.org/10.1101/2023.02.07.527523

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Neural regulation of hatching in amphibians

Many animal embryos hatch in response to threats or opportunities, yet how cue sensing activates hatching is unknown. We screened red-eyed treefrog (Agalychnis callidryas) eggs in the field with small molecules to discover that the neurotransmitter acetylcholine is a key mediator of hatching enzyme release. Using behavioral pharmacology, microscopy, and transcriptional profiling we identify direct cholinergic input on hatching gland cells that triggers enzyme release for egg rupture, and serotonergic transduction of embryonic hypoxia sensing. Independent hypoxia-sensing and mechanosensory predation-detection pathways converge on a hatching decision that elicits acetylcholine-dependent enzyme release and coordinated hatching-specific behavior. Cholinergic regulation of hatching enzyme release is conserved in a distantly related frog and salamander, suggesting a shared ancestral hatching mechanism. These results provide a neural basis for hatching plasticity which may have contributed to the evolution of diverse hatching modes in amphibians.

developmental biology↗
bioRxiv2026

Towards Understanding the Microenvironmental Control of Reindeer Antler Regeneration

Deer antlers are the only mammalian appendages capable of complete periodic regeneration and therefore provide a natural model for investigating mechanisms of skeletal regeneration. However, current knowledge of the structural and molecular characteristics of the regenerative antler microenvironment remains incomplete. Here, we compared antler tip and antler base tissues from Rangifer tarandus (reindeer) with mature metacarpal cortical bone using structural, compositional, histological, and proteomic analyses. Antler tissues exhibited smaller and less crystalline apatite structures, elevated carbonate substitution, and higher organic matrix content compared with metacarpal bone, indicating an immature mineral phase. Antlers also exhibited lower bone mineral density, greater porosity, reduced bone volume fraction, and greater trabecular separation, particularly in central regions, consistent with a dynamic remodeling microenvironment. Histological examination revealed abundant active osteons and extensive osteoid seams in antler tissues, whereas metacarpal bone predominantly comprised mature lamellar bone with limited remodeling activity. Proteomic profiling identified distinct extracellular matrix signatures between antler and metacarpal tissues. Metacarpal bone was enriched in proteins associated with skeletal homeostasis, mechanotransduction, and bone remodeling, whereas antler tissues were enriched in proteins involved in extracellular matrix reorganization, metabolic adaptation, and regeneration. Collectively, these findings indicate that reindeer antlers possess a specialized regenerative skeletal microenvironment characterized by immature mineral organization, active remodeling, and distinct molecular signatures associated with rapid tissue growth. These results provide new insights into the biological basis of mammalian appendage regeneration and may facilitate the development of regenerative strategies for bone repair and skeletal tissue engineering.

developmental biology↗
bioRxiv2026

Endogenous expression of mutant RagC in mice results in early-onset dilated cardiomyopathy with features of the Long-Olsen-Distelmaier syndrome

Dilated cardiomyopathy (DCM) is a severe heart condition often linked to arrhythmias, clots, and heart failure, for which treatments are not yet curative. Recently, de novo mutations in genes encoding components of the Rag GTPase nutrient signaling pathway, particularly in RRAGC, have been found in unrelated patients with a severe, early-onset DCM syndrome called Long-Olsen-Distelmaier. Cancer cell lines, hiPSC-derived cardiomyocytes and zebrafish have been used to study this Ragopathy, but a mammalian model to investigate this syndrome has not been generated. Here, we show that mice engineered to endogenously express mutations in Serine 74 (orthologous to the Serine 75 mutated in patients), exhibit early-onset features of DCM with decreased heart size, fibrosis, diastolic dysfunction and aortic insufficiency, characteristics reminiscent of the human syndrome. Moreover, Rragc-mutant hearts display decreased left ventricular mass and interventricular septum. Endogenous heterozygous expression of Rragc mutant variants result in a milder, sublethal defective physiological cardiac growth with increased systolic and diastolic blood pressure. Mechanistically, active RagC does not cause abnormal increase in cardiomyocyte size, but leads to suppressed transcriptional activity of Tfeb and alterations in cardiomyocyte metabolism. Transcriptional profiling of neonatal mutant hearts reveals multiple signatures of impaired mitochondrial activity. Ex vivo and in vitro analyses of murine cardiomyocyte mitochondria from Rragc-mutant mice show suppressed mitochondrial respiration, disturbed complex IV multimerization and super-complex organization. These data point to abnormal early postnatal heart metabolism by deregulated nutrient - Rag GTPase signaling with a potential molecular explanation to the early onset of DCM in patients with de novo missense mutations in RRAGC, and suggests the relevance of early metabolic interventions in conditions with altered nutrient signaling

developmental biology↗