Mongad, D. | bioRxiv Science

bioRxiv2025

Biome-specific genome catalogues reveal functional potential of shallow sequencing

The use of 16S rRNA metabarcoding for functional prediction is limited by several biases. Shallow shotgun sequencing is a cost-effective and taxonomically high-resolution alternative to 16S rRNA metabarcoding, but the low sequencing depth limits functional inference. Our BioSIFTR tool maps shallow shotgun sequencing reads against single-biome databases and extrapolates into their precalculated functional profiles. We used three datasets from red junglefowl, mice, and human gut, containing matched deep shotgun metagenomic and 16S rRNA metabarcoding data for taxonomic and functional benchmarking. An additional human gut deep shotgun sequencing data set was subsampled to 1 M reads and analysed with BioSIFTR to replicate previously obtained results. BioSIFTR taxonomic and functional profiles closely agree with the results of the full deep sequencing data in all biomes. We also replicated differences in the human gut microbiome between high and low trimethylamine N-oxide producing participants, using only < 2 % of the original deep sequencing data. The BioSIFTR tool is a powerful approach which approximates the functional information of a deep-sequenced metagenome while using only a fraction of the data. Shallow shotgun sequencing combined with BioSIFTR could be a stand-in replacement for 16S rRNA metabarcoding with an increased taxonomic and functional resolution, and lower bias. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=87 SRC="FIGDIR/small/659887v1_ufig1.gif" ALT="Figure 1"> View larger version (20K): org.highwire.dtl.DTLVardef@8ca365org.highwire.dtl.DTLVardef@13b466dorg.highwire.dtl.DTLVardef@8cad19org.highwire.dtl.DTLVardef@1b853fa_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioinformatics↗

bioRxiv2022

Prolonged exposure to insulin causes epigenetic alteration leading to insulin resistance

Glucose homeostasis is maintained by insulin. It has been observed that hyperinsulinemia precedes insulin resistance and Type 2 diabetes. Insulin resistance is caused by multiple factors including genetic and diet. The molecular mechanism underlying insulin resistance (IR) is not completely understood. Using Glut4 and insulin receptor-expressing CHO cells we had previously shown that prolonged exposure of these cells to insulin in the absence of high levels of glucose led to insulin resistance in the cells. In the present study, we have shown that the underlying cause for the impaired GLUT4 trafficking is the defective PI3K/AKT pathway. This insulin resistance is likely due to epigenetic alterations as it is stable and can be maintained for several generations even when insulin is not provided, and epigenetic modifiers can reverse the insulin resistance. We extended these studies to liver cell line (BRL-3A) and show that these cells also develop impaired insulin signaling upon exposure to insulin in the absence of high levels of glucose. Transcriptomic analysis of the insulin-sensitive and -resistance cells uncover altered signaling networks involved in chromatin remodelling, Rho GTPases, and ubiquitination. Pathway analysis reveals the role of demethylase Kdm5b and lysine methyltransferase (Kmt2a and Kmt2e) in the development of insulin resistance. It is also observed that trimethylation of histone H3 at lysine 4 (H3K4me3) is increased in insulin resistance cellular models. We further showed that mice injected with low doses of insulin when fasting develop insulin resistance with impaired glucose tolerance and increased HOMA-IR index. Altogether, these findings suggest dysregulated synthesis of insulin in the absence of glucose stimulus could lead to epigenetic alterations that may lead to insulin resistance. Summary StatementInsulin stimulation in the absence of glucose leads to insulin resistance. We have developed a cell and mouse model of insulin resistance in this study to characterise the molecular signalling involved in insulin resistance and early onset of type 2 diabetes. The transcriptomic analysis provides new insights on epi-transcriptomic regulation in insulin resistance.

molecular biology↗