# Mechanisms by which Trib1 regulates plasma lipids and glucose metabolism

> **NIH NIH F31** · UNIVERSITY OF PENNSYLVANIA · 2020 · $32,481

## Abstract

Project Summary
 Coronary artery disease (CAD) is the leading cause of mortality worldwide, for which the strongest causal
risk factors are elevated plasma levels of low-density lipoprotein cholesterol (LDL) and triglyceride (TG)-rich
lipoproteins (TRL). One of the strongest novel loci identified by genome wide association studies for plasma
lipid traits is at chromosomal locus 8q24, which contains the TRIB1 gene. TRIB1 encodes the pseudokinase,
Tribbles homolog 1 (TRIB1) which is catalytically inactive, but has been proposed to act as an adaptor and
scaffolding protein, targeting the transcription factor CEBPα for ubiquitination and proteosomal degradation.
Variants at this locus in humans are associated with lower CAD risk, lower levels of LDL, total cholesterol and
TG, and beneficially, higher levels of high-density lipoproteins (HDL). Hepatic overexpression of Trib1 in mice
results in decreased plasma lipid levels and hepatic fat, while hepatic-specific Trib1 deficiency (Trib1 LSKO)
increases plasma lipids, lipogenesis and hepatic steatosis. A tissue-specific approach was necessary because
mice homozygous for Trib1 whole body deletion (Trib1 KO) on a pure C57BL/6 background have a highly
penetrant neonatal lethality.
 My first goal is to elucidate how Trib1 hepatic deficiency leads to the plasma lipid phenotype in mice.
Plasma lipids are regulated by the balance between their rates of secretion and clearance from circulation;
both processes heavily influenced by the liver. Preliminary data shows decreased LDL clearance rate when
comparing Trib1 LSKO with control mice, suggesting that a defect in clearance could explain the phenotype.
We previously demonstrated that increased hepatic expression of Cebpa phenocopies Trib1 LSKO with
respect to increased lipogenesis and the development of hepatic steatosis. However, it is still unknown if this is
also the causal mechanism for increased plasma lipid in Trib1 LSKO mice. My preliminary data shows that
deleting Cebpa in a liver specific manner (Cebpa LSKO) induces a decrease in plasma lipids. I hypothesize
that the elevated plasma lipid phenotype in Trib1 LSKO mice is due to increase in Cebpa expression
and by impaired LDL clearance. My second goal is to determine the roles of Trib1 in regulating glucose
metabolism and to define the physiological mechanism by which Trib1 whole body deletion leads to neonatal
death. My preliminary data from neonates (less than 12 hours post-partum) shows a significant reduction in
blood glucose levels in mice homozygous and heterozygous for the Trib1 deletion compared to control mice.
Consistent with this, adult Trib1 LSKO mice exhibit rapid glucose clearance, which correlates with increased
plasma insulin levels. I propose to test the hypothesis that neonatal lethality in Trib1 KO mice is results
from severe hypoglycemia due to increased plasma insulin levels (hyperinsulinemia).
 Taken together, the proposed studies will provide substantial new insight into the molec...

## Key facts

- **NIH application ID:** 9987751
- **Project number:** 5F31HL143857-03
- **Recipient organization:** UNIVERSITY OF PENNSYLVANIA
- **Principal Investigator:** Katherine Quiroz-Figueroa
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $32,481
- **Award type:** 5
- **Project period:** 2018-08-01 → 2021-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9987751

## Citation

> US National Institutes of Health, RePORTER application 9987751, Mechanisms by which Trib1 regulates plasma lipids and glucose metabolism (5F31HL143857-03). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9987751. Licensed CC0.

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