Biology subjects

Williams, K. M.

Publications and source records attributed to Williams, K. M..

4 recordsLinked to original sources

bioRxiv2026

Replicable generation of rhesus macaque iPSCs for in vitro modeling of genetic frontotemporal dementia

At the Wisconsin National Primate Research Center, we have identified a family of rhesus carrying the microtubule-associated protein tau (MAPT) R406W mutation linked to frontotemporal dementia (FTD). Rhesus induced pluripotent stem cells (RhiPSCs) derived from these monkeys present a unique opportunity for in vitro modeling and comparison with cells derived from MAPT R406W human carriers. Here, we report the development of a reproducible method to generate RhiPSCs compliant with the standards of the International Society for Stem Cell Research (ISSCR) to support in vitro modeling of FTD-MAPT R406W. Our stepwise approach identified efficient methods for fibroblast derivation, fibroblast reprogramming to RhiPSC, and RhiPSC maintenance over continued culture. To derive fibroblasts from MAPT wild type (WT) and R406W monkeys, a combination of manual processing and overnight enzymatic digestion was required to maximize the number of low passage fibroblasts available for reprogramming. Fibroblast reprogramming to RhiPSC using Sendai viral vectors versus oriP/EBNA1 episomal plasmids revealed the latter as most efficient. Electroporation conditions for oriP/EBNA1 reprogramming were optimized to maximize plasmid uptake and cell survival. Ultimately, eight RhiPSC lines were derived from 4 donor rhesus monkeys (n=2 WT, n=2 R406W; two clonal lines per donor) and fully characterized according to ISSCR standards. RhiPSC stemness and genetic stability was best maintained on mouse embryonic fibroblast feeders in Universal Primate Pluripotency Stem Cell medium, as opposed to Essential 12 medium supplemented with IWR1, which produced cytogenetic abnormalities. Rhesus neural progenitor cells were generated using a monolayer protocol and expressed PAX6 and NESTIN after 21 days of differentiation. Our reliable method will be useful to labs seeking to derive RhiPSCs for preclinical studies. Overall, the RhiPSCs generated from MAPT R406W carriers will be a critical resource for evaluating the molecular underpinnings of tau-related neurodegeneration across primate species.

cell biology↗

bioRxiv2025

Cholinergic synaptic plasticity shapes resilience and vulnerability to tau

Synaptic dysfunction is a hallmark of Alzheimers disease (AD). Yet due to their plasticity, synapses may also adapt to early AD pathology. Here, we demonstrate that cholinergic neurons mount a presynaptic response to tau pathology in the living human brain. Using multi-tracer positron emission tomography in cognitively normal older adults at risk for AD, we observe that cholinergic neurons increase presynaptic vesicular acetylcholine transporter (VAChT) protein levels when colocalized to tau, but not amyloid. Notably, stronger VAChT responses were associated with cognitive resilience over a decade. Whole-brain single-nucleus RNA sequencing in human and mouse tissue reveal that cholinergic neurons are enriched for a plasticity gene-network anchored to the microtubule-associated protein tau (MAPT) gene. In mice, forebrain-specific deletion of VAChT impairs cortical plasticity and hippocampal structural integrity. Overall, our findings identify cholinergic synaptic plasticity, and its failure, as a fundamental mechanism of resilience and vulnerability to tau in presymptomatic AD.

neuroscience↗

bioRxiv2020

Disparate Bone Anabolic Cues Activate Bone Formation by Regulating the Rapid Lysosomal Degradation of Sclerostin Protein

The down regulation of sclerostin mediates bone formation in response to mechanical cues and parathyroid hormone (PTH). To date, the regulation of sclerostin has been attributed exclusively to the transcriptional downregulation that occurs hours after stimulation. Here, we describe, for the first time, the rapid post-translational degradation of sclerostin protein by the lysosome following mechanical load or PTH. We present a unifying model, integrating both new and established mechanically- and hormonally-activated effectors into the regulated degradation of sclerostin by lysosomes. Using an in vivo mechanical loading model, we find transient inhibition of lysosomal degradation or the upstream mechano-signaling pathway controlling sclerostin abundance impairs subsequent load-induced bone formation. We also link dysfunctional lysosomes to aberrant sclerostin regulation using Gaucher disease iPSCs. These results inform a paradigm shift in how bone anabolic cues post-translationally regulate sclerostin and expands our understanding of how osteocytes regulate this fundamentally important protein to regulate bone formation.

cell biology↗

bioRxiv2018

Methamphetamine Administration Increases Proceptive Behavior by Activating Src Kinase and Upregulating Progesterone Receptor in the Medial Amygdala

Methamphetamine, a psychostimulant drug of abuse, increases sexual motivation both in humans and in rodent models. The activation of dopamine type-1 receptors (D1Rs) within the medial amygdala, in the presence of ovarian hormones (EB+P), are both necessary and sufficient for increases in proceptive, or sexually motivated, behaviors. Here, we demonstrate that methamphetamine increases progesterone receptor expression in the medial amygdala independently of D1R activation, and that lentiviral overexpression of the progesterone receptor was able to recapitulate the methamphetamine-induced enhancement of proceptive behaviors. Furthermore, we found that within the medial amygdala, these progesterone receptors show an increase in phosphorylation of serine 294 of the progesterone receptor in a region-specific manner. The involvement of this phosphorylation site suggests a role for cytosolic kinases, which may be responsible for enhanced progesterone receptor action. The phosphorylation of serine 294 is blocked by D1R antagonists, and by inhibiting cSrc and ERK1/2, downstream of D1R signaling, we identified that Src and ERK1/2 are required for enhanced proceptive behavior. Taken together, we propose that within the medial amygdala, methamphetamine enhances progesterone receptors sensitivity to its cognate ligand via interaction with cSrc kinase and ERK1/2, as well as an increase total progesterone receptors, thus leading to enhanced proceptive behaviors in the rat.

neuroscience↗