Biology subjects

Lopez-Pajares, V.

Publications and source records attributed to Lopez-Pajares, V..

6 recordsLinked to original sources

bioRxiv2026

Tissue geometry patterns epidermal stem cell fate in murine interfollicular skin

How tissues maintain spatial patterns of stem cell renewal and differentiation despite continuous cellular turnover remains poorly understood. Here, we show that microscopic undulations of the dermal-epidermal junction (DEJ) are associated with distinct stem cell behaviors in the mouse epidermis. Using longitudinal intravital imaging and quantitative analysis of cell morphology and lineage dynamics, we find that local DEJ curvature predicts the subsequent fate of daughter cells up to three days before mother cell division. Cells residing in concave valleys preferentially produce proliferating descendants, whereas convex ridges are associated with increased differentiation. These spatial biases are reflected in the expression of stem- and differentiation-associated markers and accumulate into differences in long-term clonal expansion. Remarkably, DEJ geometry remains stable for weeks, persisting across multiple generations of epidermal cells. Moreover, human epidermal equivalents grown on devitalized dermis recapitulate the preferential retention of basal layer cells in valleys, indicating that living dermal cells are not required for this spatial organization. Our findings suggest that stable tissue architecture can pattern stem cell fate probabilities across generations, contributing to functional stem cell heterogeneity.

developmental biology↗

bioRxiv2025

Thermal proteome profiling identifies glucose binding proteins involved in metabolic disease

Recent work has shown that glucose can directly bind non-enzymatic proteins to modulate their function. We sought to build on this work by adapting thermal proteome profiling screens to uncover novel glucose interactors involved in metabolism. Proteome integral solubility alternation (PISA) profiling nominated 23 proteins with glucose-induced thermal solubility, including two proteins strongly implicated in metabolic disease, TSC22D4 and IGF2BP2. First, we characterized glucose binding of TSC22D4, an intrinsically disordered leucine zipper protein strongly implicated in hepatic steatosis. MST confirmed direct glucose-protein interaction of TSC22D4. UV-crosslinking mass spectrometry identified putative glucose binding at the C-terminal leucine zipper. Mutating isoleucine 322 to tryptophan (I322W) abolishes glucose binding. Crosslinking-MS and chemo-proteomic experiments suggest that glucose increases accessibility of the leucine zipper region, resulting in intra-protein contacts between C-terminal zipper domain and N-terminal intrinsically-disordered domain. TSC22D4 associates with fatty acid metabolism machinery proteins in response to high glucose conditions, suggesting a possible role for TSC22D4 in altering fatty acid metabolism. Next, we characterized glucose-binding in IGF2BP2, an RNA-binding protein essential for beta cell insulin secretion. We first confirmed direct IGF2BP2-glucose interaction and created glucose-binding mutant Y40A based on computational docking predictions. IGF2BP2Y40A exhibited a dominant negative impact on proliferation and insulin secretion in MIN6-6 beta cells. Glucose increased IGF2BP2 binding to client mRNAs Igf2 and Pdx1, which has previously been demonstrated to mediate its impact on insulin secretion. Thus, our data suggests that IGF2BP2 directly binds glucose to enhance insulin secretion.

biochemistry↗

bioRxiv2025

The Adhesion GPCR ADGRL2 engages Gα13 to Enable Epidermal Differentiation

Homeostasis relies on signaling networks controlled by cell membrane receptors. Although G-protein-coupled receptors (GPCRs) are the largest family of transmembrane receptors, their specific roles in the epidermis are not fully understood. Dual CRISPR-Flow and single cell Perturb-seq knockout screens of all epidermal GPCRs were thus performed, uncovering an essential requirement for adhesion GPCR ADGRL2 (latrophilin 2) in epidermal differentiation. Among potential downstream guanine nucleotide-binding G proteins, ADGRL2 selectively activated G13. Perturb-seq of epidermal G proteins and follow-up tissue knockouts verified that G13 is also required for epidermal differentiation. A cryo-electron microscopy (cryo-EM) structure in lipid nanodiscs showed that ADGRL2 engages with G13 at multiple interfaces, including via a novel interaction between ADGRL2 intracellular loop 3 (ICL3) and a G13-specific QQQ glutamine triplet sequence in its GTPase domain. In situ gene mutation of this interface sequence impaired epidermal differentiation, highlighting an essential new role for an ADGRL2-G13 axis in epidermal differentiation.

cell biology↗

bioRxiv2024

Disease-Linked Regulatory DNA Variants and Homeostatic Transcription Factors in Epidermis

Identifying noncoding single nucleotide variants (SNVs) in regulatory DNA linked to polygenic disease risk, the transcription factors (TFs) they bind, and the target genes they dysregulate is a goal in polygenic disease research. Massively parallel reporter gene analysis (MPRA) of 3,451 SNVs linked to risk for polygenic skin diseases characterized by disrupted epidermal homeostasis identified 355 differentially active SNVs (daSNVs). daSNV target gene analysis, combined with daSNV editing, underscored dysregulated epidermal differentiation as a pathomechanism shared across common polygenic skin diseases. CRISPR knockout screens of 1772 human TFs revealed 108 TFs essential for epidermal progenitor differentiation, uncovering novel roles for ZNF217, CXXC1, FOXJ2, IRX2 and NRF1. Population sampling CUT&RUN of 27 homeostatic TFs identified allele-specific DNA binding (ASB) differences at daSNVs enriched near epidermal homeostasis and monogenic skin disease genes, with notable representation of SP/KLF and AP-1/2 TFs. This resource implicates dysregulated differentiation in risk for diverse polygenic skin diseases.

genetics↗

bioRxiv2022

Glucose modulates transcription factor dimerization to enable tissue differentiation

Glucose is a universal energy currency for living organisms, however, its non-energetic functions in processes such as differentiation are undefined. In epidermis, differentiating cells exhibit dynamic changes in gene expression1-4 driven by specific transcription factors (TFs)5-9. The interplay between such TFs and biomolecules that also change in this process is not understood. Metabolomic analyses revealed that increased intracellular glucose accompanies differentiation of epidermal keratinocytes. This elevation also occurred in differentiating cells from other tissues and was verified in epidermal tissue engineered with glucose sensors, which detected a glucose gradient that peaked in the outermost differentiated layers. Free glucose accumulation, unaccompanied by its increased metabolism, was essential for epidermal differentiation and required GLUT1, GLUT3, and SGLT1 transporters. Glucose affinity chromatography and azido-glucose click chemistry uncovered glucose binding to diverse regulatory proteins, including the IRF6 TF, whose epidermal knockout confirmed its requirement in glucose-dependent differentiation. Direct glucose binding enabled IRF6 dimerization, DNA binding, genomic localization, and induction of IRF6 target genes, including essential pro-differentiation TFs GRHL1, GRHL3, HOPX and PRDM1. The IRF6R84C mutant found in undifferentiated cancers was unable to bind glucose. These data identify a new role for glucose as a gradient morphogen that modulates protein multimerization in cellular differentiation.

molecular biology↗

bioRxiv2022

RET activation controlled by MAB21L4-CacyBP interaction drives squamous cell carcinoma

Epithelial squamous cell carcinomas (SCC) most commonly originate in the skin, where they display disruptions in the normally tightly regulated homeostatic balance between keratinocyte proliferation and terminal differentiation. We performed a transcriptome-wide screen for genes of unknown function that possess inverse expression patterns in differentiating keratinocytes compared to cutaneous SCC (cSCC) and identified MAB21L4 (C2ORF54) as an enforcer of terminal differentiation that suppresses carcinogenesis. Loss of MAB21L4 in human cSCC organoids enabled malignant transformation through increased expression of the receptor tyrosine kinase rearranged during transfection (RET). In addition to transcriptional upregulation of RET, MAB21L4 deletion preempted recruitment of the CacyBP-Siah1 E3 ligase complex to RET and reduced its ubiquitylation. Both genetic disruption of RET or selective RET inhibition with BLU-667 (pralsetinib) suppressed tumorigenesis in SCC organoids and in vivo tumors while inducing concomitant differentiation. Our results suggest that targeting RET activation is a potential therapeutic strategy for treating SCC. Statement of SignificanceFew targeted therapies are available to individuals with cSCC who seek or require non-surgical management. Our study demonstrates that downregulation of RET is required for epithelial differentiation and opposes carcinogenesis in cSCC as well as SCC arising from other epithelial tissues.

cancer biology↗