Biology subjects

Gerlitz, G.

Publications and source records attributed to Gerlitz, G..

8 recordsLinked to original sources

bioRxiv2026

SETDB1 promotes tubulin deacetylation and Golgi fragmentation by HDAC6

Microtubules (MTs) are dynamic cytoskeletal structures essential for intracellular transport, cell division, and organelle positioning. Their functions are regulated by post-translational modifications, including -tubulin acetylation at Lys40, which enhances MT stability and resilience. Histone deacetylase 6 (HDAC6) is the primary enzyme that reverses this modification, but its access to the luminal Lys40 residue is restricted. Previously, we identified SETDB1, a histone methyltransferase and known oncogene, as a cytoplasmic regulator of MT dynamics, attenuating MT polymerization and destabilizing MTs. Here, we uncover the molecular mechanism by which SETDB1 destabilizes MTs. SETDB1 interacts with HDAC6 and promotes its tubulin deacetylation activity. Mechanistically, SETDB1 enhances HDAC6 recruitment to polymerized MTs and induces repairable damage along MT shafts, generating entry points for HDAC6 into the MT lumen. Functionally, this axis regulates Golgi organization: SETDB1 overexpression disperses the Golgi in an HDAC6-dependent manner, while SETDB1 knockdown or HDAC6 inhibition compacts it. Notably, SETDB1s role in Golgi regulation is independent of its methyltransferase activity. These findings reveal crosstalk among the histone methylation machinery, MT dynamics, and Golgi organization. Since Golgi dispersal is thought to promote tumorigenesis, our results suggest that the SETDB1-HDAC6 axis is a potential therapeutic target. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=109 SRC="FIGDIR/small/734187v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@1857973org.highwire.dtl.DTLVardef@1e8a73eorg.highwire.dtl.DTLVardef@13c11deorg.highwire.dtl.DTLVardef@b937b1_HPS_FORMAT_FIGEXP M_FIG C_FIG

Cell Biology↗

bioRxiv2025

ERM proteins support perinuclear actin rim formation

The interaction of actin filaments with the nuclear envelope is essential for diverse cellular processes, including cell migration, nuclear positioning, and transcriptional control. The main studied mechanism that links F-actin to the nucleus is the Linker of Nucleoskeleton and Cytoskeleton (LINC) complex. Recently, the formation of a perinuclear actin rim has been identified in various cell types in response to external force or migration signals. This rim depends on the activation of the actin nucleator Inverted formin 2 (INF2) by calcium influx. However, it is not clear how the rim is coupled with the nuclear envelope. Here we show that the nuclear membrane protein Emerin, which has an actin-binding domain, is not required for the perinuclear actin rim formation. Interestingly, we found that the Ezrin-Radixin-Moesin (ERM) proteins, known to link actin filaments to the cell membrane, are also localized to the nuclear envelope in melanoma cells. Overexpression of ERM proteins increased the perinuclear actin rim levels, while knockdown of ERM proteins led to a reduction in the rim levels. Thus, the ERM proteins appear as part of the mechanism that links actin filaments to the nuclear envelope.

cell biology↗

bioRxiv2023

CTCF supports melanoma cell migration by repressing cholesterol biosynthesis

CTCF is a key factor in three-dimensional chromatin folding and transcriptional control that was found to affect cancer cell migration by a mechanism that is still poorly understood. To identify this mechanism, we used mouse melanoma cells with a partial loss of function (pLoF) of CTCF. We found that CTCF pLoF inhibits cell migration rate while leading to an increase in the expression of multiple enzymes in the cholesterol biosynthesis pathway along with an elevation in the cellular cholesterol levels. Inhibition of cholesterol synthesis in CTCF pLoF cells restored the cellular migration rate, suggesting that CTCF supports cell migration by suppressing cholesterol synthesis. Detailed analysis of the promoter of Hmgcs1, an early enzyme in the cholesterol synthesis pathway, revealed that CTCF enables PRC2 recruitment to the promoter and deposition of H3K27me3 to prevent SREBP2 binding and activation of transcription. By this mechanism CTCF fine-tunes cholesterol levels to support cell migration. Notably, genome wide association studies suggest a link between CTCF and cholesterol-associated diseases, thus CTCF emerges as a new regulator of cholesterol biosynthesis.

genomics↗

bioRxiv2023

CTCF is essential for proper mitotic spindle structure and anaphase segregation

Mitosis is an essential process in which the duplicated genome is segregated equally into two daughter cells. CTCF has been reported to be present in mitosis but its importance for mitotic fidelity remains to be determined. To evaluate the importance of CTCF in mitosis, we tracked mitotic behaviors in wild type and two different CTCF CRISPR-based genetic knockdowns. We find that knockdown of CTCF results in prolonged mitoses and failed anaphase segregation via time lapse imaging of SiR-DNA. CTCF knockdown did not alter cell cycling or the mitotic checkpoint, which was activated upon nocodazole treatment. Immunofluorescence imaging of the mitotic spindle in CTCF knockdowns revealed disorganization via tri/tetrapolar spindles and chromosomes behind the spindle pole. Imaging of interphase nuclei showed that nuclear size increased drastically, consistent with failure to divide the duplicated genome in anaphase. Population measurements of nuclear shape in CTCF knockdowns do not display decreased circularity or increased nuclear blebbing relative to wild type. However, failed mitoses do display abnormal nuclear morphologies relative to successful mitoses, suggesting population images do not capture individual behaviors. Thus, CTCF is important for both proper metaphase organization and anaphase segregation which impacts the size and shape of the interphase nucleus.

cell biology↗

bioRxiv2021

Homologous recombination repair creates mutations in the non-coding genome that alter Topoisomerase-1 cleavage sites & orchestrates irinotecan resistance

Resistance to chemotherapy is a leading cause of treatment failure. Drug-resistance mechanisms involve mutations in specific proteins or changes in their expression levels. It is commonly understood that resistance mutations happen randomly prior to treatment and are selected during the treatment. However, selection of drug-resistant mutants in culture could be achieved by multiple drug exposures of cloned genetically identical cells, and thus cannot result from selection of pre-existent mutations. Accordingly, adaptation must involve generation of mutations de-novo upon drug treatment. Here we explored the origin of resistance mutations to a widely used Top1 inhibitor irinotecan, which triggers DNA breaks, causing cytotoxicity. Resistance mechanism involved gradual accumulation of recurrent mutations in non-coding regions of DNA at Top1-cleavage sites. Surprisingly, cancer cells had higher number of such sites than reference genome, which may define their increased sensitivity to irinotecan. Homologous recombination repair of DNA double strand breaks at these sites following initial drug exposures gradually reverted cleavage-sensitive "cancer" sequences back to cleavage-resistant "normal" sequences. These mutations reduced generation of DNA breaks upon subsequent exposures, thus gradually increasing the drug resistance. Together, large target size for mutations and their Top1-guided generation lead to their gradual and rapid accumulation, synergistically accelerating development of resistance. Abstract Figure O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=78 SRC="FIGDIR/small/470089v3_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@d9d93forg.highwire.dtl.DTLVardef@45b88forg.highwire.dtl.DTLVardef@157cafeorg.highwire.dtl.DTLVardef@cff4a4_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2021

SETDB1 regulates microtubule dynamics

SETDB1 is a methyltransferase responsible for the methylation of histone H3-lysine-9, which is mainly related to heterochromatin formation. SETDB1 is overexpressed in various cancer types and is associated with an aggressive phenotype. In agreement with its activity, it mainly exhibits a nuclear localization; however, in several cell types a cytoplasmic localization was reported. Here we show that a substantial cytoplasmic pool of SETDB1 is colocalized with microtubules. Significantly, silencing of SETDB1 led to faster polymerization and reduced rate of catastrophe events of microtubules in parallel to reduced proliferation rate and slower mitotic kinetics. Interestingly, over-expression of either wild-type or catalytic dead SETDB1 altered microtubule polymerization rate to the same extent, suggesting that SETDB1 affects MT dynamics by a methylation-independent mechanism. Finding interaction between SETDB1 and the tubulin deacetylase HDAC6 and increased tubulin acetylation levels upon silencing of SETDB1 suggest a model in which SETDB1 affects microtubule dynamics by interacting with both microtubules and HDAC6 to enhance tubulin deacetylation. Overall, our results suggest a novel cytoplasmic role for SETDB1 in the regulation of microtubule dynamics.

cell biology↗

bioRxiv2020

Reduced nuclear lamin A/C enhances cancer cell squeezing through rigid barriers, does not facilitate endothelial crossing, and impairs experimental metastasis

The mechanisms by which the nuclear lamina of tumor cells controls their migration and survival are poorly understood. Lamin A and its variant lamin C are key nuclear lamina proteins that control nucleus stiffness and chromatin conformation. Downregulation of lamin A/C levels in two metastatic lines, B16F10 melanoma and E0771 breast carcinoma, facilitated cell squeezing through rigid pores, elevated nuclear deformability and reduced heterochromatin. Unexpectedly, the transendothelial migration of both cancer cells in vitro and in vivo, through lung capillaries, was not elevated by lamin A/C knockdown. Both cancer cells with lamin A/C knockdown grew normally in primary tumors and in vitro on rigid surfaces. Strikingly, however, both lamin A/C deficient melanoma and breast cancer cells grew poorly in 3D spheroids expanded in soft agar cultures. Experimental lung metastasis of both lamin A/C knockdown cells was also markedly reduced. Taken together, our results suggest that high content of lamin A/C in multiple cancer cells promotes cancer cell survival and ability to generate lung metastasis without compromising cancer cell emigration from lung vessels.

cancer biology↗

bioRxiv2018

The heterochromatin landscape in migrating cells and the importance of H3K27me3 for migration-associated transcriptional changes

H3K9me3, H3K27me3 and H4K20me1 are epigenetic markers associated with chromatin condensation and transcriptional repression. Previously, we found that migration of melanoma cells is associated with and dependent on global chromatin condensation that includes a global increase in these markers. Taken together with more recent reports by others suggest it is a general signature of migrating cells. Here, to learn about the function of these markers in migrating cells we mapped them by ChIP-seq analysis. This analysis revealed that induction of migration leads to expansion of these markers along the genome and to an increased overlapping between them. Significantly, induction of migration led to a higher increase in H3K9me3 and H4K20me1 signals at repetitive elements than at protein-coding genes, while an opposite pattern was found for H3K27me3. Transcriptome analysis revealed that 182 altered genes following induction of migration, of which 33% are dependent on H3K27me3 for these changes. H3K27me3 was also required to prevent changes in the expression of 501 other genes upon induction of migration. Taken together our results suggest that heterochromatinization in migrating cells is global and not restricted to specific genomic loci and that H3K27me3 is a key component in executing a migration-specific transcriptional plan.

cell biology↗