Biology subjects

Schaner Tooley, C.

Publications and source records attributed to Schaner Tooley, C..

4 recordsLinked to original sources

bioRxiv2026

Characterization of novel cytoplasmic roles for the N-terminal methyltransferase NRMT1

N-terminal methylation of proteins by the trimethylase NRMT1 plays important roles in oncogenesis, development, and aging. As N-terminal methylation has frequently been shown to regulate protein-DNA interactions, and many NRMT1 substrates are transcription factors or regulators of chromatin structure, previous research has focused on how transcriptional regulation by NRMT1 affects cell growth and differentiation. However, we have recently identified a new, cytoplasmic role for NRMT1, inhibiting the eukaryotic elongation factor 1 alpha (eEF1A) methyltransferase METTL13, which indicates NRMT1 could also be acting as a translational regulator. Here we further explore NRMT1 cytoplasmic functions and show that, unlike previously thought, NRMT1 can methylate substrates in the cytoplasm. We also show that while many of these substrates remain bound to NRMT1, it can also interact with a number of non-target ribosomal proteins and proteins associated with the endoplasmic reticulum (ER). To confirm NRMT1 interaction with the ribosome, we performed polysome profiling, which showed a portion of NRMT1 co-migrates with the 40S and 60S subunits but not with actively translating polysomes, indicating NRMT1 may play an early role in translation. To see if NRMT1 was affecting target mRNA selection of ribosomes, we also performed ribosome-sequencing experiments in proliferating and differentiating C2C12 mouse myoblasts. These results show a striking upregulation of translation of soluble proteins with NRMT1 loss and corresponding decrease in translation of transmembrane and signal sequence-containing proteins. We now propose a model where NRMT1 regulates the translation of transmembrane and secreted proteins by facilitating interactions between the ribosome and the ER.

biochemistry↗

bioRxiv2025

Neuroinflammation links the neurogenic and neurodegenerative phenotypes of Nrmt1-/- mice

It is widely thought that age-related damage is the single biggest contributing factor to neurodegenerative diseases. However, recent studies are beginning to indicate that many of these diseases may have developmental origins that become unmasked overtime. It has been difficult to prove these developmental origins, as there are still few known links between defective embryonic neurogenesis and progressive neurodegeneration. We have created a constitutive knockout mouse for the N-terminal methyltransferase NRMT1 (Nrmt1-/- mice). Nrmt1-/- mice display phenotypes associated with premature aging. Specifically in the brain, they exhibit age-related striatal and hippocampal degeneration, which is accompanied by impaired short and long-term memory. These phenotypes are preceded by depletion of the postnatal neural stem cell (NSC) pools, which appears to be driven by their premature differentiation and migration. However, this differentiation is often incomplete, as many resulting neurons cannot permanently exit the cell cycle and ultimately undergo apoptosis. Here, we show that the onset of apoptosis corresponds to increased cleavage of p35 into the CDK5 activator p25, which can promote neuroinflammation. Accordingly, Nrmt1-/- brains exhibit an increase in pro-inflammatory cytokine signaling, astrogliosis, complement activation, microgliosis, and markers of a compromised blood brain barrier, all of which indicate an activated neuroimmune response. We also find Nrmt1-/- mice do not activate a corresponding anti-inflammatory response. These data indicate that abnormal neurogenesis can trigger neuroinflammation, which in the absence of compensatory anti-inflammatory signaling, could lead to neuronal apoptosis and progressive neurodegeneration.

neuroscience↗

bioRxiv2021

Novel regulation of the transcription factor ZHX2 by N-terminal methylation

N-terminal methylation (N-methylation) by the methyltransferase NRMT1 is an important post-translational modification that regulates protein-DNA interactions. Accordingly, its loss impairs functions that are reliant on such interactions, including DNA repair and transcriptional regulation. Global loss of N-methylation results in severe developmental and premature aging phenotypes, but given over 300 predicted substrates, it is hard to discern which physiological substrates contribute to each phenotype. One of the most striking phenotypes in NRMT1 knockout (Nrmt1-/-) mice is early liver degeneration. To identify the disrupted signaling pathways leading to this phenotype and the NRMT1 substrates involved, we performed RNA-sequencing analysis of control and Nrmt1-/- adult mouse livers. We found both a significant upregulation of transcripts in the cytochrome P450 (CYP) family and downregulation of transcripts in the major urinary protein (MUP) family. Interestingly, transcription of both families is inversely regulated by the transcription factor zinc fingers and homeoboxes 2 (ZHX2). ZHX2 contains a non-canonical NRMT1 consensus sequence, indicating its function could be directly regulated by N-methylation. We confirmed misregulation of CYP and MUP mRNA and protein levels in Nrmt1-/- livers and verified NRMT1 can methylate ZHX2 in vitro. In addition, we used mutants of ZHX2 that cannot be methylated to directly demonstrate N-methylation promotes ZHX2 transcription factor activity. Finally, we show Nrmt1-/- mice also exhibit early postnatal de-repression of ZHX2 targets involved in fetal liver development. Taken together, these data implicate continual ZHX2 misregulation as a driving force behind the liver phenotype seen in Nrmt1-/- mice.

biochemistry↗

bioRxiv2021

Age-related neurodegeneration and cognitive impairments of NRMT1 knockout mice are preceded by misregulation of RB and expansion of the neural stem cell population

N-terminal methylation is an important post-translational modification that regulates protein/DNA interactions and plays a role in many cellular processes, including DNA damage repair, mitosis, and transcriptional regulation. Our generation of a constitutive knockout mouse for the N-terminal methyltransferase NRMT1, demonstrated its loss results in severe developmental abnormalities and premature aging. As premature aging is often accompanied by neurodegeneration, we more specifically examined how NRMT1 loss affects neural pathology and cognitive behaviors. Here we find that Nrmt1-/- mice exhibit postnatal enlargement of the lateral ventricles, age-dependent striatal and hippocampal neurodegeneration, memory impairments, and hyperactivity. These morphological and behavior abnormalities are preceded by alterations in neural stem cell (NSC) development. Depletion of quiescent NSC pools in Nrmt1-/- mice is concurrent with expansion of intermediate progenitor and neuroblast pools. These phenotypes are similar to those seen with loss of the NRMT1 target retinoblastoma protein (RB), and we see that NRMT1 loss leads to derepression of RB target genes and abnormal RB phosphorylation and degradation. As also seen with RB loss, neurons in Nrmt1-/- mice fail to exit cell cycle and ultimately undergo NOXA-mediated apoptosis, indicating that early misregulation of RB in Nrmt1-/- mice promotes premature NSC proliferation and contributes to subsequent neurodegenerative phenotypes.

neuroscience↗