# In vivo and in vitro rare coding variant analyses to identify modulations of the adipocyte differentiation pathway that affect T2D risk

> **NIH NIH R01** · BOSTON CHILDREN'S HOSPITAL · 2022 · $671,741

## Abstract

Abstract
 Type 2 diabetes (T2D) is a highly prevalent disease for which new therapies are needed. The adipocyte
differentiation and lipid storage pathways are involved in rare and common forms of diabetes and are targeted
by thiazolidinediones (TZDs), which are efficacious but cause undesirable complications. Designing better
therapies to target adipocyte differentiation/lipid storage is impeded by incomplete knowledge of which genes
in these pathways are relevant to T2D in humans, or how they might be modulated to achieve therapeutic
efficacy. Disease-associated rare coding variants directly identify human disease-relevant gene modulations,
and our recent study of 45,231 exomes suggested that such associations are likely observable within many
genes within the adipocyte differentiation and lipid storage pathways. However, rare variant associations
require large datasets to detect, and methods are currently lacking to identify which observed associations are
most likely to (a) represent causal links to disease and (b) act through effects on a pathway of interest. The
proposed project will address these gaps under the hypothesis that T2D-susceptibility rare coding variants
that modulate the adipocyte differentiation/lipid storage pathways should impair these processes in vitro and
predispose in vivo to an “insulin resistance signature” of higher T2D risk, higher BMI-adjusted fasting insulin
levels, higher triglyceride levels, lower hip circumference, and lower HDL levels.
Specific aim 1 hypothesizes that larger exome datasets will identify new gene-level rare coding variant
T2D associations, and that prior knowledge of gene function should affect the likelihood each association is
causal. Coding variants in 150K-600K exomes will be tested for association with T2D and insulin resistance,
and each gene's probability of causal association will be calculated by a new method to account for its
empirically estimated prior likelihood of association. Specific aim 2 hypothesizes that genes associated with
an insulin resistance signature in vivo should have a higher likelihood of impairing adipocyte differentiation/lipid
storage when ablated in vitro, and that within these genes, only variants that fail to complement effects
observed in vitro should increase T2D risk in vivo. Fifty genes with gene-level T2D associations will be
screened via loss-of-function experiments in human pre-adipocytes, and genetic complementation experiments
will be conducted for 50 variants in each of 5 genes whose ablation impairs adipocyte differentiation/lipid
storage.
 Significance: T2D-associated coding variants with in vitro effects on adipocyte differentiation or lipid
storage would suggest molecular gene perturbations to protect from or treat T2D. These and all other results of
the project will be made publicly accessible through the NIDDK-funded AMP-T2D Knowledge Portal. The
proposed approaches also apply to other biological processes and diseases.

## Key facts

- **NIH application ID:** 10375554
- **Project number:** 5R01DK125490-03
- **Recipient organization:** BOSTON CHILDREN'S HOSPITAL
- **Principal Investigator:** Jason Flannick
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $671,741
- **Award type:** 5
- **Project period:** 2020-07-01 → 2025-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10375554

## Citation

> US National Institutes of Health, RePORTER application 10375554, In vivo and in vitro rare coding variant analyses to identify modulations of the adipocyte differentiation pathway that affect T2D risk (5R01DK125490-03). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10375554. Licensed CC0.

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