Biology subjects

Sucharov, J.

Publications and source records attributed to Sucharov, J..

3 recordsLinked to original sources

bioRxiv2026

COUNTERING AGE-ASSOCIATED ALTERATIONS IN OLIGODENDROCYTE-DERIVED EXTRACELLULAR MATRIX REJUVENATES COGNITION

Efforts to rejuvenate age-related cognitive decline have predominantly targeted neurons, often overlooking non-neuronal cell types in the aging brain. Here, we show that countering alterations in oligodendrocyte-derived extracellular matrix (ECM) in the aging hippocampus restores cognition. We identify broad age-associated transcriptional and proteomic changes in oligodendrocytes, including dysregulation of the matrisome, with marked upregulation of ECM components and associated regulators with age. Among these, we detect an increase in Hyaluronan and proteoglycan link protein 2 (HAPLN2), an oligodendrocyte-derived core matrisome protein that locates specifically at the nodes of Ranvier, in the hippocampus of aged mice and older humans. Hapln2 overexpression in oligodendrocytes of young mice recapitulated age-related memory impairments. Conversely, abrogating the age-related increase in Hapln2 induced synaptic plasticity-related hippocampal transcriptional signatures and improved memory in aged mice. Together, these data define oligodendrocyte-derived ECM remodeling as a hallmark of brain aging that can be targeted to rescue cognitive decline.

neuroscience↗

bioRxiv2024

The Gq/11 family of Gα subunits is necessary and sufficient for lower jaw development

Vertebrate jaw development is coordinated by highly conserved ligand-receptor systems such as the peptide ligand Endothelin 1 (Edn1) and Endothelin receptor type A (Ednra), which are required for patterning of lower jaw structures. The Edn1/Ednra signaling pathway establishes the identity of lower jaw progenitor cells by regulating expression of numerous patterning genes, but the intracellular signaling mechanisms linking receptor activation to gene regulation remain poorly understood. As a first step towards elucidating this mechanism, we examined the function of the Gq/11 family of G subunits in zebrafish using pharmacological inhibition and genetic ablation of Gq/11 activity and transgenic induction of a constitutively active Gq protein in edn1-/- embryos. Genetic loss of Gq/11 activity fully recapitulated the edn1-/- phenotype, with genes encoding G11 being most essential. Furthermore, inducing Gq activity in edn1-/-embryos not only restored Edn1/Ednra-dependent jaw structures and gene expression signatures but also caused homeosis of the upper jaw structure into a lower jaw-like structure. These results indicate that Gq/11 is necessary and sufficient to mediate the lower jaw patterning mechanism for Ednra in zebrafish. Summary statementGq/11 is the signaling mediator downstream of Endothelin 1 and Endothelin Receptor Type A that drives tissue patterning for all lower jaw structures in zebrafish.

developmental biology↗

bioRxiv2022

Variable paralog expression underlies phenotype variation

Human faces are variable; we look different from one another. Craniofacial disorders further increase this variability. Here we used the zebrafish mef2ca mutant, which produces variable phenotypes, to understand craniofacial variation. Comparing different mef2ca alleles demonstrated that severity, measured by penetrance and expressivity, correlates with variation. Years of selective breeding for low and high penetrance produced strains that are either resilient, or sensitive, to the mef2ca mutation. Comparing these strains further demonstrates that severity correlates with variation. Gene expression studies indicated that selective breeding upregulated and downregulated mef2ca paralog expression in the low- and high-penetrance strains, respectively. We hypothesized that heritable paralog expression variation underlies mutant phenotype variation. In support, mutagenizing all mef2ca paralogs in the low-penetrance strain demonstrated modular buffering by paralogs. Specifically, some paralogs buffer severity while others buffer variability. We present a novel, mechanistic model for phenotypic variation where cryptic vestigial paralog expression modularly buffers development and contributes to evolution. These studies are a major step forward in understanding of the mechanisms of facial variation, including how some genetically resilient individuals can overcome a deleterious mutation.

genetics↗