Biology subjects

Colaiacovo, M. P.

Publications and source records attributed to Colaiacovo, M. P..

8 recordsLinked to original sources

bioRxiv2025

Unsaturated Fatty Acids Are Required for Germline Proliferation and Membrane Structural Integrity in Caenorhabditis elegans

Unsaturated fatty acids (UFAs) are critical components of membrane lipids, but their specific roles in germline development and reproductive health remain poorly defined. Here, we investigated the consequences of UFA depletion in the Caenorhabditis elegans germline using an auxin-inducible degron (AID) system to conditionally degrade FAT-7, the major {Delta}9 stearoyl-CoA desaturase, in a fat-5; fat-6 double mutant background. This strategy bypassed the lethality associated with complete loss of {Delta}9 desaturase activity, enabling analysis of UFA deficiency in adult animals. UFA depletion led to a dramatic reduction in brood size, elevated embryonic and larval lethality, and a severe loss of germline nuclei. We found that UFAs are essential for mitotic proliferation, DNA replication, and chromosome organization in the germline. Moreover, reduced UFA levels impaired meiotic progression, accompanied by loss of membrane integrity in the syncytial germline. Notably, UFA deficiency increased nuclear pore complex (NPC) signal intensity, suggesting alterations to the nuclear envelope (NE). Together, our findings demonstrate that UFAs are indispensable for germline maintenance, affecting cell cycle progression, chromosome organization, and membrane architecture. These results underscore a fundamental link between acyl chain composition and reproductive success, highlighting the critical role of lipid homeostasis in the germline. SummaryUnsaturated fatty acids (UFAs) are essential for fertility, but their role in germline maintenance remains unclear. In this study, we used Caenorhabditis elegans to examine how UFA depletion affects the germline. By conditionally disrupting UFA synthesis, we found that low UFA levels impair germline mitotic proliferation, DNA replication, meiotic progression, and germline membrane structures. These findings demonstrate that lipid composition is critical for germline maintenance and highlight a broader role for fatty acids in reproductive health, offering insights relevant to metabolic and fertility disorders in humans.

genetics↗

bioRxiv2024

An inducible and reversible system to regulate unsaturated fatty acid biosynthesis in C. elegans

Unsaturated fatty acids (UFAs) play crucial roles in various physiological and pathological processes. In animals, these lipids are synthesized from saturated fatty acids through the action of delta 9 ({Delta}9) desaturases. In C. elegans, three {Delta}9 desaturases are encoded by the genes fat-5, fat-6, and fat-7. The presence of multiple {Delta}9 desaturases has posed a significant challenge in developing a rapid and efficient approach to control UFA production in C. elegans and other model organisms. Utilizing the auxin-inducible degradation system, we specifically targeted the C. elegans fat-7 gene, responsible for the major stearoyl-CoA desaturase (SCD), while deleting fat-5 and fat-6. This design resulted in a strain that can be reversibly depleted of UFAs in the cells of interest. Conditional depletion in all somatic cells exhibited a pronounced auxin-dependent defect in UFA production. Using this system, we uncovered an essential requirement for de novo UFA production during L1 and L2 stage. Moreover, our results support a direct connection between UFA levels, fat storage and increased lipid turnover. This system will enable further studies exploring the cellular and physiological consequences of impairing UFA biosynthesis at different developmental stages or in specific tissues. SummaryUnsaturated fatty acids (UFAs) are essential for life. In animals, UFAs are synthesized by {Delta}9 desaturase enzymes. Caenorhabditis elegans possesses three {Delta}9 desaturase genes: fat-5, fat-6, and fat-7. We engineered a strain where fat-7 can be reversibly switched off while fat-5 and fat-6 are deleted, allowing precise control of UFA levels throughout the life cycle. Our findings demonstrate the critical role of UFA biosynthesis in early development and its direct link to fat storage and lipid turnover. This strain enables the study of UFA-related physiological and pathological processes in animals.

genetics↗

bioRxiv2024

Genetic and physical interactions reveal overlapping and distinct contributions to meiotic double-strand break formation in C. elegans

Double-strand breaks (DSBs) are the most deleterious lesions experienced by our genome. Yet, DSBs are intentionally induced during gamete formation to promote the exchange of genetic material between homologous chromosomes. While the conserved topoisomerase-like enzyme Spo11 catalyzes DSBs, additional regulatory proteins-- referred to as "Spo11 accessory factors"-- regulate the number, timing, and placement of DSBs during meiotic prophase ensuring that SPO11 does not wreak havoc on the genome. Despite the importance of the accessory factors, they are poorly conserved at the sequence level suggesting that these factors may adopt unique functions in different species. In this work, we present a detailed analysis of the genetic and physical interactions between the DSB factors in the nematode Caenorhabditis elegans providing new insights into conserved and novel functions of these proteins. This work shows that HIM-5 is the determinant of X-chromosome-specific crossovers and that its retention in the nucleus is dependent on DSB-1, the sole accessory factor that interacts with SPO-11. We further provide evidence that HIM-5 mediates interactions with the different accessory factors sub-groups, providing insights into how components on the DNA loops may interact with the chromosome axis.

developmental biology↗

bioRxiv2023

Germline mitotic quiescence and programmed cell death are induced in C. elegans by exposure to pathogenic P. aeruginosa

The impact of exposure to microbial pathogens on animal reproductive capacity and germline physiology is not well understood. The nematode Caenorhabditis elegans is a bacterivore that encounters pathogenic microbes in its natural environment. How pathogenic bacteria affect host reproductive capacity of C. elegans is not well understood. Here, we show that exposure of C. elegans hermaphrodites to the Gram-negative pathogen Pseudomonas aeruginosa causes a marked reduction in brood size with concomitant reduction in the number of nuclei in the germline and gonad size. We define two processes that are induced that contribute to the decrease in the number of germ cell nuclei. First, we observe that infection with P. aeruginosa leads to the induction of programmed germ cell death. Second, we observe that this exposure induces mitotic quiescence in the proliferative zone of the C. elegans gonad. Importantly, these processes appear to be reversible; when animals are removed from the presence of P. aeruginosa, germ cell death is abated, germ cell nuclei numbers increase, and brood sizes recover. The reversible germline dynamics during exposure to P. aeruginosa may represent an adaptive response to improve survival of progeny and may serve to facilitate resource allocation that promotes survival during pathogen infection.

genetics↗

bioRxiv2022

GRAS-1 is a conserved novel regulator of early meiotic chromosome dynamics in C. elegans

Chromosome movements and licensing of synapsis must be tightly regulated during early meiosis to ensure accurate chromosome segregation and avoid aneuploidy, although how these steps are coordinated is not fully understood. Here we show that GRAS-1, the worm homolog of mammalian GRASP/Tamalin and CYTIP, coordinates early meiotic events with cytoskeletal forces outside the nucleus. GRAS-1 localizes close to the nuclear envelope (NE) in early prophase I and interacts with NE and cytoskeleton proteins. Delayed homologous chromosome pairing, synaptonemal complex (SC) assembly, and DNA double-strand break repair progression are partially rescued by the expression of human CYTIP in gras-1 mutants, supporting functional conservation. However, Tamalin, Cytip double knockout mice do not exhibit obvious fertility or meiotic defects, suggesting evolutionary differences between mammals. gras-1 mutants show accelerated chromosome movement during early prophase I, implicating GRAS-1 in regulating chromosome dynamics. GRAS-1-mediated regulation of chromosome movement is DHC-1-dependent, placing it acting within the LINC-controlled pathway, and depends on GRAS-1 phosphorylation at a C-terminal S/T cluster. We propose that GRAS-1 serves as a scaffold for a multi-protein complex coordinating the early steps of homology search and licensing of SC assembly by regulating the pace of chromosome movement in early prophase I.

cell biology↗

bioRxiv2022

CRTC-1 Balances Histone Trimethylation and Acetylation to Promote Longevity

Loss of function during ageing is accompanied by transcriptional drift, altering gene expression and contributing to a variety of age-related diseases. CREB-regulated transcriptional coactivators (CRTCs) have emerged as key regulators of gene expression that might be targeted to promote longevity. Here, we define the role of the Caenorhabditis elegans CRTC-1 in the epigenetic regulation of longevity. Endogenous CRTC-1 binds chromatin factors, including components of the COMPASS complex, which trimethylates lysine 4 on histone H3 (H3K4me3). CRISPR editing of endogenous CRTC-1 reveals that the CREB-binding domain in neurons is specifically required for H3K4me3-dependent longevity. However, this effect is independent of CREB but instead acts via the transcription factor AP-1. Strikingly, CRTC-1 also mediates global histone acetylation levels, and this acetylation is essential for H3K4me3-dependent longevity. Indeed, overexpression of an acetyltransferase enzyme is sufficient to promote longevity in wild-type worms. CRTCs, therefore, link energetics to longevity by critically fine-tuning histone acetylation and methylation to promote healthy ageing.

genetics↗

bioRxiv2018

The tumor suppressor BRCA1/BARD1 complex localizes to the synaptonemal complex and regulates recombination under meiotic dysfunction in Caenorhabditis elegans

Breast cancer susceptibility gene 1(BRCA1) and binding partner BRCA1-associated RING domain protein 1 (BARD1) form an essential E3 ubiquitin ligase important for DNA damage repair and homologous recombination. In Caenorhabditis elegans BRCA1/BRC-1 and BARD1/BRD-1 orthologs are not essential, but function in DNA damage repair and homologous recombination, as well as in meiosis. In proliferating germ cells and in early meiotic prophase, BRC-1 and BRD-1 are nucleoplasmic, with enrichment at foci that partially overlap with the recombinase RAD-51. In mid-pachytene, BRC-1 and BRD-1 are observed on tracks, before concentrating to the short arms of bivalents, co-localizing with a central region component of the synaptonemal complex. We found that BRD-1 is essential for BRC-1 to associate with chromatin and the synaptonemal complex, but BRC-1 is not required for BRD-1 localization; the complex fails to properly localize in the absence of either meiotic recombination or chromosome synapsis. Inactivation of BRC-1/BRD-1 enhances the embryonic lethality of mutants that perturb chromosome synapsis and crossover recombination, suggesting that BRC-1/BRD-1 plays an important role in monitoring recombination in the context of the synaptonemal complex. We discovered that BRC-1/BRD-1 stabilizes the RAD51 filament when the formation of a crossover-intermediate is disrupted. Further, in the absence of BRC-1/BRD-1 crossover distribution is altered, and under meiotic dysfunction, crossover numbers are perturbed. Together, our studies indicate that BRC-1/BRD-1 localizes to the synaptonemal complex where it serves a checkpoint function to monitor and modulate meiotic recombination.\n\nProject SummaryOur genomes are passed down from one generation to the next through the specialized cell division program of meiosis. Meiosis is highly regulated to coordinate both the large scale chromosomal and fine scale DNA events to ensure fidelity. We analyzed the role of the tumor suppressor BRCA1/BARD1 complex in meiosis in the worm, Caenorhabditis elegans. We find that BRCA1/BARD1 localizes dynamically to the proteinaeous structure that aligns maternal and paternal chromosomes, where it regulates crossover recombination. Although BRCA1/BARD1 mutants have only subtle meiotic defects, we show that this complex plays a critical role in meiotic recombination when meiosis is perturbed. These results highlight the complexity of ensuring accurate transmission of the genome and uncover the requirement for this conserved complex in meiosis. As women carrying BRCA1 mutations with no indication of cancer have fertility defects, our results provide insight into why BRCA1 mutations impact reproductive success.

genetics↗

bioRxiv2018

Fanconi Anemia FANCM/FNCM-1 and FANCD2/FCD-2 are required for maintaining histone methylation levels and interact with the histone demethylase LSD1/SPR-5 in C. elegans

The histone demethylase LSD1 was originally discovered as removing methyl groups from di- and monomethylated histone H3 lysine 4 (H3K4me2/1), and several studies suggest it plays roles in meiosis as well as epigenetic sterility given that in its absence there is evidence of a progressive accumulation of H3K4me2 through generations. In addition to transgenerational sterility, growing evidence for the importance of histone methylation in the regulation of DNA damage repair has attracted more attention to the field in recent years. However, we are still far from understanding the mechanisms by which histone methylation is involved in DNA damage repair and only a few studies have been focused on the roles of histone demethylases in germline maintenance. Here, we show that the histone demethylase LSD1/CeSPR-5 is interacting with the Fanconi Anemia (FA) protein FANCM/CeFNCM-1 based on biochemical, cytological and genetic analyses. LSD1/CeSPR-5 is required for replication stress-induced S-phase checkpoint activation and its absence suppresses the embryonic lethality and larval arrest observed in fncm-1 mutants. FANCM/CeFNCM-1 re-localizes upon hydroxyurea exposure and co-localizes with FANCD2/CeFCD-2 and LSD1/CeSPR-5 suggesting coordination between this histone demethylase and FA components to resolve replication stress. Surprisingly, the FA pathway is required for H3K4me2 maintenance regardless of the presence of replication stress. Our study reveals a connection between Fanconi Anemia and epigenetic maintenance, therefore providing new mechanistic insight into the regulation of histone methylation in DNA repair.

genetics↗