Anthocyanin-rich extract from black beans exerts anti-diabetic effects in rats through a multi-genomic mode of action in adipose tissue

Abstract

Black beans (BB) are an important source of a range of plant bioactive compounds including polyphenols, particularly anthocyanins. Several studies support that consumption of BB is associated with health benefits, including prevention of type 2 diabetes mellitus (T2DM). However, molecular mechanisms underlying the potential health properties of BB on adipose tissue (AT) are still largely unknown. The purpose of this study was to investigate multi-genomic effects of BB intake and identify regulatory networks potentially mediating T2DM on AT. Male Wistar diabetic rats consumed an anthocyanin-rich black bean extract for 5 weeks. Global gene expression from AT, protein coding and non-coding RNA profiles were determined using RNAseq. Biological function analyses were performed using a variety of bioinformatic tools. The evaluation of global gene expression profiles exhibited significant change following BB consumption with 406 significantly differentially expressed genes, 33 miRNA and 39 lncRNA and 3 snRNA. Functional analyses indicated that these genes play an important role in regulation of PI3K signaling, NIN/NF-kB signaling, insulin secretion, and endoplasmic reticulum (ER) organization. Interestingly, transcription factors such as GATA2, or POU2AF1 demonstrated to modulate their activity by BB extract by direct interaction with polyphenol metabolites, or by interactions with cell signaling proteins, like PKB, AKT or PI3K, that could control transcription factor activity and as a result impact on adipogenesis regulation. Therefore, the constant consumption of an anthocyanin-rich black bean extract may have anti-diabetic protective effects by modulating gene expression, resulting in a promising alternative for T2DM patients.

Keywords: adipose tissue; anthocyanins; black beans; multi-genomics; nutrigenomics; polyphenols; type 2 diabetes mellitus.

FIGURE 1

Effects of 5 weeks consumption of an anthocyanin-rich BB extract on (A) fasting blood glucose; (B) body weight; (C) glucose levels at the end of the treatment; (D) adipose tissue weight; (E) insulin levels; and (F) TNF-α levels. Values represent the mean and S.D. (n = 8). ^**p ≤ 0.01; ^***p ≤ 0.001 and ^*⁣*⁣**p ≤ 0.0001 when BB were compared to the corresponded value of DB.

FIGURE 2

Pie chart of the number of differentially expressed mRNAs, miRNAs, and lncRNAs in diabetic rats treated with anthocyanin-rich black beans extract.

FIGURE 3

(A) Bar graph of enriched gene ontology (GO) terms across input gene list, colored by p-values. (B) Subset of enriched terms selected to create a network analysis. Terms with a similarity > 0.03 are connected by edges. Bigger nodes represent larger gene sets. The analyzes were performed in Metascape and visualized with the Cytoscape tool.

FIGURE 4

Pathway enrichment analysis from up and downregulated differentially expressed genes in (A) BB group (diabetic rats treated with Anthocyanin-rich black beans extract). (B) DB group (diabetic rats without treatment).

FIGURE 5

Protein-protein interaction network. (A) Interactions between proteins encoded by genes modulated by anthocyanin-rich black beans extract supplementation in diabetic rats. (B) Top genes forming major interaction nodes in the network. (C) Pathway enrichment analyses of hub proteins encoded by genes.

FIGURE 6

In silico docking analysis of interactions between main anthocyanins found in black bean extract and potential transcription factors. (A) Delphinidin 3-glucoside to GATA2; (B) Delphinidin 3-glucoside to POU2AF1; (C) Petunidin 3-glucoside to GATA2; (D) Petunidin 3-glucoside to POU2AF1; (E) Malvidin 3-glucoside to GATA2; (F) Malvidin 3-glucoside to POU2AF1.

FIGURE 7

Bioinformatic analyses of differentially expressed miRNA and their target mRNA. (A) Network of miRNA significantly modulated with consumption of anthocyanin-rich black beans extract and their target mRNA. (B) KEGG pathways associated with miRNA modulated with consumption of anthocyanin-rich black beans extract. (C) Reactome pathways associated with miRNA modulated with consumption of anthocyanin-rich black beans extract.

FIGURE 8

Summary figure representing multi-omic results and genomic modifications induced in diabetic rats by anthocyanin-rich black beans extract supplementation.