Biology subjects

Rowbotham, S. P.

Publications and source records attributed to Rowbotham, S. P..

4 recordsLinked to original sources

bioRxiv2026

Histone methylation activity of KMT2D is required for proliferative control of the developing lung

KMT2D, the histone methyltransferase and core component of the COMPASS/MLL4 complex, has been implicated in developmental diseases such as Kabuki Syndrome, interstitial lung disease, and congenital diaphragmatic hernia, with clear links to pediatric pulmonary disorders. Despite this, the mechanism by which KMT2D governs lung development remains unclear. Knock-in mouse models rendering, KMT2D catalytically deactivated (KMT2DKI) and reducing H3K4 methylation, have demonstrated potential in defining KMT2Ds role in pulmonary development. Our examination of the lungs of KMT2DKI mice revealed increased cellular density and impaired sacculation indicated by reduced airspace chord length, thickening of intersaccular septa, and abnormal alveolar cell differentiation. KMT2DKI mice revealed narrowed Sox2+ conducting airways and epithelial differentiation defects characterized by reduced Cc10+ club cells. Accompanying the alveolar and airway hypoplasia, blood vessel luminal area was reduced. Conversely, KMT2DKI lungs had a significantly higher proportion of proliferating cells accompanied by a dramatic expansion in Pdgfr+ mesenchymal progenitor cells. Our findings therefore suggest that KMT2D-mediated H3K4 methylation is vital to normal lung development, and its impairment results in widespread pulmonary hypoplasia and potentially pulmonary hypertension.

developmental biology↗

bioRxiv2026

Modeling patient variants of Cnot1 and Cdc42bpb results in distinct forms of congenital diaphragmatic hernia in mice

Congenital diaphragmatic hernia (CDH) is a severe congenital anomaly characterized by impairment of both diaphragm and lung development in utero. CDH presents as a spectrum of forms and severities, with diaphragm defects arising in the dorsal/posterior region typically correlating with more severe pulmonary disease and higher risk of mortality than those appearing in ventral/anterior regions. The genetic etiology underlying CDH is complex, with many genes implicated showing variable expressivity and incomplete penetrance in both human patients and mouse models. Here we present in vivo validation of two genes previously unassociated with CDH: the CDC42-interacting kinase CDC42BPB; and CNOT1, a scaffolding protein of the CCR4-NOT protein complex, critical for mRNA regulation through modifications such as deadenylation. Each gene was found to have a damaging, de novo missense variant in a recent large-scale CDH patient sequencing screen. Loss of Cdc42bpb leads to ventral diaphragmatic hernias, heart septal defects and minor lung epithelial differentiation defects in mouse embryos. Installation of the orthologous patient-specific missense variant through CRISPR/Cas9 editing leads to less severe ventral diaphragm defects. Mouse embryos with either one or two copies of the orthologous Cnot1 variant, c.1867C>T (p.R623W), develop dorsal diaphragmatic hernias with low (<50%) penetrance, and mutants showed alterations in mRNA isoform expression consistent with the molecular role of Cnot1 in RNA splicing. These results underscore the power of in vivo functional modeling to validate genes and patient-specific variants uncovered by patient sequencing, reveal two previously unrecognized genetic causes of CDH, and highlight the heterogeneity of different patient anatomic presentations.

genetics↗

bioRxiv2024

Airway injury induces alveolar epithelial and mesenchymal responses mediated by macrophages

Airway injury activates local progenitors and stimulates cell-cell interactions to restore homeostasis, but it is unknown how distal niches are impacted. We utilized mouse models of airway-specific epithelial injury to examine secondary tissue-wide alveolar and immune responses. Single-cell transcriptomics and in vivo validation of mouse models of airway-specific epithelial injury revealed transient, tissue-wide proliferation of alveolar type 2 (AT2) progenitor cells after club cell-specific injury or ablation. Myeloid cells exhibited altered gene expression after club cell loss and were detectable in the bronchoalveolar lavage fluid. The AT2 cell proliferative response was reliant on alveolar macrophages (AMs) exhibiting an injury-induced gene expression program. Overall, these results demonstrate that acute airway damage can trigger myeloid-mediated lung alveolar responses that may contribute to disease susceptibility or dysfunction.

cell biology↗

bioRxiv2021

Chromatin alterations in the aging lung change progenitor cell activity

The lung contains multiple progenitor cell types that respond to damage, but how their responses are choreographed and why they decline with age is poorly understood. We report that histone H3 lysine 9 di-methylation (K9me2), mediated by histone methyltransferase G9a, regulates the dynamics of lung epithelial progenitor cells, and this regulation deteriorates with age. In aged mouse lungs, K9me2 loss coincided with lower frequency and activity of alveolar type 2 (AT2) cell progenitors. In contrast, K9me2 loss resulted in increased frequency and activity of multipotent progenitor cells with bronchiolar and alveolar potential (BASCs) and bronchiolar progenitors. K9me2 depletion in young mice through deletion or inhibition of G9a decreased AT2 progenitor activity and impaired alveolar injury regeneration. Conversely, K9me2 depletion increased chromatin accessibility of bronchiolar cell genes, increased BASC frequency and accelerated bronchiolar repair. K9me2 depletion also resulted in increased bronchiolar cell expression of the SARS-CoV2 receptor Ace2 in aged lungs. These data point to K9me2 and G9a as a critical regulator of the balance of lung progenitor cell regenerative responses and prevention of susceptibility to age-related lung diseases. These findings indicate that epigenetic regulation coordinates progenitor cell populations to expedite regeneration in the most efficient manner and disruption of this regulation presents significant challenges to lung health.

molecular biology↗