Biology subjects

Hahne, M.

Publications and source records attributed to Hahne, M..

8 recordsLinked to original sources

bioRxiv2025

Pyruvate promotes ciliogenesis bypassing IFT88 dependency and attenuates DSS-induced colitis

Primary cilia (PC) are important signaling rheostats, yet their biology in colon remains understudied. We previously reported that the presence of PC on colonic fibroblasts in mice (CF) modulates their susceptibility to colitis. Here, we demonstrate that extracellular pyruvate levels influence both ciliary length and ciliogenesis in CF. Pyruvate supplementation to CF enhanced tubulin and histone acetylation, with the latter promoting MAPK signaling and tubulin detyrosination within PC. MAPK-inhibition reduced tubulin detyrosination and shortened ciliary length, while inhibition of -tubulin acetylation specifically affected ciliogenesis. Col6a1cre-Ift88flx/flx mice, lacking ciliary Ift88 gene in Col6a1-expressing CF, displayed reduced ciliogenesis and increased susceptibility to DSS-induced colitis. Surprisingly, in primary CF cultures from these mice, pyruvate supplementation restored PC formation. Moreover, pyruvate administration via drinking water rescued PC formation in Col6a1cre-Ift88flx/flx mice and attenuated DSS-induced colitis. These findings identify pyruvate as a regulator of PC biology in CF and as a therapeutically relevant factor in colitis. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=172 HEIGHT=200 SRC="FIGDIR/small/694572v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@170091dorg.highwire.dtl.DTLVardef@66870corg.highwire.dtl.DTLVardef@12c5124org.highwire.dtl.DTLVardef@834660_HPS_FORMAT_FIGEXP M_FIG Pyruvate promotes ciliogenesis bypassing IFT88 dependency and attenuates DSS-induced colitis C_FIG

pathology↗

bioRxiv2025

TTLL6-mediated Polyglutamylation of PurA Maintains Colonic Crypt Integrity

The tubulin tyrosine ligase-like (TTLL) family comprises enzymes catalyzing posttranslational modifications of tubulin, including glutamylation and glycylation. We previously described a critical role for the monoglycylase TTLL3 in colon. Here, we identified TTLL6 as the predominant polyglutamylase in the colon, specifically expressed in epithelial cells of distal and transverse segments. TTLL6 expression decreases during CRC progression, correlating with poor patient prognosis. Deletion of Ttll6 in mice resulted in elongated colonic crypts, expansion of stem and transit-amplifying compartments, and increased numbers of differentiated epithelial cells. Moreover, Ttll6-deficient mice showed an elevated susceptibility to chemically induced colon carcinogenesis. Notably, we identified the nucleic acid-binding protein PurA as a novel TTLL6 substrate with both proteins mutually required for nuclear localization. Consistently, both nuclear polyglutamylation and PurA were present in the bottom compartment of control colons, but reduced in Ttll6-deficient colons. These findings reveal a TTLL6-PurA axis being critical in maintaining colonic homeostasis.

cell biology↗

bioRxiv2025

Machine Learning-Based Drug Response Prediction Identifies Novel Therapeutic Candidates for Colorectal Cancer Cell Line KM-12

One major hurdle in the discovery of new drugs is the limited capacity of traditional screening methods to efficiently explore the immense space of drug candidates. To bypass this difficulty, computational approaches such as virtual screening (VS) have been developed supported by Machine Learning (ML) models to predict the activities of drug-like molecules on a given target. We developed a ML model for VS of a library of 25 million highly-diverse synthesis-on-demand molecules against the KM-12 colorectal cancer (CRC) cell line. By combining different biological readouts, we discovered compounds with a novel chemical scaffold, not yet described in the context of CRC, with either a prominent cytotoxic or cytostatic effect. This finding underpins the strength of our ML-guided VS protocol in discovering promising CRC drug leads triggering altered biological responses.

cancer biology↗

bioRxiv2024

Co-translational sorting enables a single mRNA to generate distinct polysomes with different localizations and protein fates

{beta}-catenin is a multi-functional protein playing essential roles in tissue homeostasis and cancer. It bridges E-cadherin to the cytoskeleton and also activates transcription in response to Wnt. Plasma membrane {beta}-catenin is stable whereas without Wnt, cytoplasmic {beta}-catenin is degraded by the destruction complex, composed of APC and Axin. Here, we show that APC and Axin associate with many mRNAs and that this occurs via the nascent protein chains. Notably, APC and Axin bind {beta}-catenin mRNAs present as either single polysome or polysome condensates, and co-translational interactions constitute the major fraction of their binding to the {beta}-catenin protein. Remarkably, E-cadherin also binds {beta}-catenin co-translationally, and {beta}-catenin mRNAs localize either with APC in the cytosol or E-cadherin at the plasma membrane. Thus, co-translational interactions sort {beta}-catenin mRNAs into distinct polysome populations that spatially segregate in cells and synthesize proteins with different functions. Co-translational polysome sorting provides a mechanism to regulate the fate of multi-functional proteins.

molecular biology↗

bioRxiv2023

Anti-inflammatory role of APRIL by modulating regulatory B cells in antigen-induced arthritis

APRIL (A Proliferation-Inducing Ligand) acts as a secreted factor and plays important roles in B cell biology and chronic inflammation. The reported capacity of APRIL to stimulate B cells in vitro raised the hypothesis that APRIL may be a disease promoter in autoimmune diseases such as rheumatoid arthritis. In contrast, there is large evidence that B Lymphocyte Stimulator Factor (BAFF) can break B cell tolerance in mice and humans. This study was undertaken to examine the ability of APRIL to regulate B cell-mediated inflammatory response in a model of antigen-induced arthritis (AIA) in mice. AIA was induced by administration of antigen (mBSA) into the knee joints of previously immunized APRIL-transgenic (Tg) mice and their littermates. Flow cytometry was used to analyze the different inflammatory cell populations in spleen and draining lymph nodes in acute and chronic disease, while cytokine levels were assessed by ELISA. In the acute stage of disease APRIL-Tg mice displayed a decrease in joint swelling, disease score and inflammatory infiltrate in articular tissues, as compared with their littermates. In addition, we observed a decrease of cellularity in draining lymph nodes of APRIL-Tg mice. Flow cytometry analysis revealed an increase of CD19+IgM+CD5+ cell population in draining lymph nodes and increase of CD19+CD21hiCD23hi (B regulatory) cells in APRIL-Tg mice with arthritis and, increase of IL-10 and CXCL13 production in vitro.

immunology↗

bioRxiv2019

Partial loss of colonic primary cilia promotes inflammation and carcinogenesis

Primary cilia (PC) are important signaling hubs in cells and their deregulation has been associated with various diseases including cancer. Here we explored the role of PC in colorectal cancer (CRC) and colitis. In the colon we found PC to be mostly present on different subtypes of fibroblasts. Colons of mice exposed to either chemically induced colitis-associated colon carcinogenesis (CAC) or dextran sodium sulfate (DSS)-induced colitis had decreased numbers of PC. We employed conditional knock-out strains for the PC essential genes, Kif3A and Ift88, to generate mice with reduced numbers of PC on colonic fibroblasts. These mice showed an increased susceptibility in the CAC model as well as in DSS-induced colitis. Colons from DSS-treated mice with PC-deficiency on fibroblasts displayed an elevated production of the pro-inflammatory cytokine IL-6 and colonic epithelial cells had diminished levels of HES-1, a key transcription factor of Notch signaling. Notably, an analysis of PC presence on biopsies of patients with ulcerative colitis as well as CRC patients revealed decreased numbers of PC on colonic fibroblasts in pathological versus surrounding normal tissue. Taken together, we provide evidence that a decrease in colonic PC numbers promotes colitis and CRC. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=177 HEIGHT=200 SRC="FIGDIR/small/871772v2_ufig1.gif" ALT="Figure 1"> View larger version (42K): org.highwire.dtl.DTLVardef@1f8eccdorg.highwire.dtl.DTLVardef@1829b3borg.highwire.dtl.DTLVardef@19d632aorg.highwire.dtl.DTLVardef@1d9833b_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2019

The R2TP chaperone assembles cellular machineries in intestinal CBC stem cells and progenitors

The R2TP chaperone cooperates with HSP90 to integrate newly synthesized proteins into multi-subunit complexes, yet its role in tissue homeostasis is unknown. Here, we generated conditional, inducible knock-out mice for Rpap3 to inactivate this core component of R2TP in the intestinal epithelium. In adult mice, Rpap3 invalidation caused destruction of the small intestinal epithelium, and death within 10 days. Levels of R2TP substrates were decreased, with strong effects on mTOR, ATM and ATR. Rpap3-deficient CBC stem cells and progenitors also failed to import RNA polymerase II in the nucleus. This correlated with p53 activation, cell cycle arrest and apoptosis. Interestingly, post-mitotic, differentiated cells did not display any of those alterations, indicating that R2TP clients are built in actively proliferating cells. Analyses of tissues from colorectal cancer patients revealed that high RPAP3 levels correlate with bad cancer prognosis. Thus, in the intestine, the R2TP chaperone functions in physiologic and pathologic proliferation.

developmental biology↗

bioRxiv2019

Loss of cyclin A2 in murine colonic epithelial cells disrupts colon homeostasis by triggering DNA damage and dysplasia and high cyclin A2 expression is a good-prognosis factor in patients with colorectal cancer

To clarify the function of cyclin A2 in colon homeostasis and colorectal cancer (CRC) we generated mice deficient for cyclin A2 in colonic epithelial cells (CEC). Colons of those mice displayed architectural changes in the mucosa, and signs of inflammation as well as an increased proliferation of CEC associated with the appearance of low- and high-grade dysplasia. The main initial events triggering those alterations in cyclin A2 deficient CEC appear to be abnormal mitoses and DNA damage. Cyclin A2 deletion in CEC promoted the development of dysplasia and adenocarcinomas in the murine colitis-associated cancer model. We next explored the status of cyclin A2 expression in clinical CRC samples at the mRNA and protein level and found higher expression in tumors of stage I and II patients compared to those of stage III and IV. A meta-analysis of 11 transcriptome datasets comprising 2,239 primary CRC tumors displayed different CCNA2 (the mRNA coding for cyclin A2) expression levels among the CRC tumor subtypes with highest in CMS1 and lowest in CMS4. Moreover, high expression of CCNA2 was found to be a good prognosis factor independently from other prognostic factors for the CMS1, CMS3 and CMS4 subtypes.\n\n\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=112 SRC=\"FIGDIR/small/690404v1_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (36K):\norg.highwire.dtl.DTLVardef@d9de04org.highwire.dtl.DTLVardef@17f0b4forg.highwire.dtl.DTLVardef@1bf9748org.highwire.dtl.DTLVardef@16520df_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗