Biology subjects

Proehl, J.

Publications and source records attributed to Proehl, J..

4 recordsLinked to original sources

bioRxiv2025

Mus Musculus papillomavirus MmuPV1 resists restriction by human APOBEC3B

The single-stranded DNA deaminase APOBEC3B (A3B) is capable of potently restricting the replication of a range of viruses including retroviruses (cDNA) and herpesviruses (genomic DNA). However, these and likely other DNA virus families have evolved host species-specific counter-defenses that are equally potent and serve to protect viral DNA from restriction. Although high-risk human papillomavirus (HPV) infection triggers A3B upregulation, potentially as part of an antiviral response, the impact of this restriction factor on papillomavirus replication and pathogenesis has yet to be assessed. To study human A3B antiviral function in the absence of a species-specific counter-defense, here we ask whether human A3B is capable of restricting Mus musculus papillomavirus (MmuPV1) in cellulo and in vivo. First, we created human A3B and catalytic mutant A3B-E255A expressing FVB/N mice. Second, MmuPV1 gene expression and replication was quantified in primary keratinocytes from these animals and, surprisingly, enzymatically active human A3B caused no measurable impairment in viral transcript or DNA accumulation. Third, A3B, catalytic mutant A3B-E255A, and nontransgenic FVB/N animals were infected with MmuPV1 and similar pathologies were found regardless of A3B functionality. Thus, despite likely never being exposed to human A3B during evolution, MmuPV1 appears to be unaffected by this potent, primate-specific antiviral factor. These results suggest that MmuPV1 and perhaps papillomaviruses more broadly possess a conserved mechanism to efficiently escape restriction by human A3B and related DNA deaminases. IMPORTANCEHuman papillomaviruses (HPVs) are nearly ubiquitous, and persistent infection with high-risk types causes approximately 5% of cancers worldwide. Although HPV vaccination is effective for preventing infection, insufficient global coverage and a rising incidence of HPV-associated malignancies, such as oropharyngeal carcinoma, highlight the need to understand innate virus clearance mechanisms. APOBEC3 enzymes are a central component of the mammalian innate immune system and are hypothesized to restrict papillomavirus infection, particularly between species. Here, we establish mice that express the human antiviral enzyme APOBEC3B (A3B). Surprisingly, we find that human A3B is incapable of blocking the replication of a murine papillomavirus (Mus musculus papillomavirus 1, MmuPV1) in relevant primary cells from these animals or in infected tissues in vivo. These findings highlight the complexity of teasing apart host-pathogen interactions and suggest that papillomaviruses may have a general mechanism for escaping restriction by antiviral enzymes such as A3B.

microbiology↗

bioRxiv2025

Murine models for triple-negative breast cancer with differential responsiveness to immunotherapy

Breast cancer is the most common cancer diagnosis in women. Clinical studies with triple-negative breast cancer (TNBC) are encouraging for immunotherapy combined with chemotherapy (anti-PD-1 with paclitaxel and/or carboplatin). However, additional clinical advances may be pursued more rapidly with assistance from preclinical TNBC models including syngeneic mammary tumor cell lines. Here, we report two mammary tumor cell lines that exhibit differential responsiveness to immunotherapy in vivo. Spontaneous mammary tumors from C57BL/6J MMTV-Cre Trp53fl/+ animals were passaged serially in cell culture and in vivo in the mammary fat pad of fully wildtype animals. The resulting lines, MM001i and MM008i, lost Trp53 and formed 1000 mm3 tumors in the mammary fat pad within 21-28 days. Despite originating from the same genetic background, these lines exhibit differential responses to immunotherapy. For anti-PD-1 therapy, MM001i is poorly responsive and MM008i is strongly responsive with near-complete tumor regression. In comparison, both MM001i and MM008i respond rapidly to anti-CTLA-4 therapy. Both models express unique tumor antigens as evidenced by immunity to subsequent engraftments. Primary MM008i tumors exhibit greater T cell infiltration, and CD8-positive T lymphocytes are required for anti-PD-1 responses. These TNBC models are promising for further mechanistic studies and testing future single and combinatorial therapies.

cancer biology↗

bioRxiv2025

Tobacco smoke carcinogens exacerbate APOBEC mutagenesis and carcinogenesis

Mutational processes are thought to act independently and additively. We challenge this view by demonstrating that DNA-adducting agents sensitize the genome to mutagenesis by APOBEC enzymes. A model tobacco carcinogen (NQO) triggers a 100-fold increase in APOBEC3B- catalyzed signature mutations and elevates oral carcinoma levels in vivo. A hallmark of this unidirectional synergy is strand-coordinated pairs of APOBEC signature mutations within 32nt of each other (didyma). Biochemical experiments show that APOBEC3B can catalyze didyma formation, and genetic studies demonstrate requirements for APOBEC3B and functional nucleotide excision repair (XPA in human cells and Rad14 in yeast). Analyses of lung and head & neck cancers show that APOBEC mutagenesis and didyma are elevated in tumors from smokers compared to non-smokers. Additional tumor types with links to DNA-adducting agents also exhibit didyma. These studies support a model in which DNA-adducting carcinogens activate nucleotide excision repair and amplify mutagenesis by APOBEC enzymes in cancer.

cancer biology↗

bioRxiv2023

Human APOBEC3B promotes tumor heterogeneity in vivo including signature mutations and metastases

The antiviral DNA cytosine deaminase APOBEC3B has been implicated as a source of mutation in many different cancers. Despite over 10 years of work, a causal relationship has yet to be established between APOBEC3B and any stage of carcinogenesis. Here we report a murine model that expresses tumor-like levels of human APOBEC3B after Cre-mediated recombination. Animals appear to develop normally with full-body expression of APOBEC3B. However, adult males manifest infertility and older animals of both sexes show accelerated rates of tumorigenesis (mostly lymphomas or hepatocellular carcinomas). Interestingly, primary tumors also show overt heterogeneity, and a subset spreads to secondary sites. Both primary and metastatic tumors exhibit increased frequencies of C-to-T mutations in TC dinucleotide motifs consistent with the established biochemical activity of APOBEC3B. Elevated levels of structural variation and insertion-deletion mutations also accumulate in these tumors. Together, these studies provide the first cause-and-effect demonstration that human APOBEC3B is an oncoprotein capable of causing a wide range of genetic changes and driving tumor formation in vivo.

cancer biology↗