# Test System for Studying Biotin Transport upon SLC5A6 Gene Inactivation

## TL;DR

This paper introduces a new system to study how cells take in biotin when a specific gene is turned off, revealing alternative transport routes.

## Contribution

A novel test system using modified HEK293 cells to study biotin transport independent of the SLC5A6 gene.

## Key findings

- Biotin and its methyl ester derivative can enter cells without the SLC5A6 transporter.
- A biotin derivative with p-aminophenylalanine is taken up only through the hSMVT transporter.
- The system can help develop therapies for SLC5A6 gene mutations.

## Abstract

This paper introduces a test system for the investigation of biotin transport
following inactivation of the SLC5A6 gene, which encodes the
sodium-dependent multivitamin transporter SLC5A6. The aim was to develop a
method for assessing the efficiency of biotin penetration across the cell
membrane following inactivation of the SLC5A6 gene and to
explore the feasibility of delivering biotin derivatives into cells independent
of SLC5A6. The test system is built upon modified HEK293 cell lines with
overexpression of the BirA* biotin ligase, with the first line comprising a
functional SLC5A6 gene and the second one involving an
inactivated version of this gene mimicking impaired biotin transport. This test
system was used to investigate the transport of biotin and its two derivatives,
namely the biotin conjugate with p-aminophenylalanine (Bio-1)
and biotin methyl ester (Bio-2), through the cell membrane. It has been
determined that biotin and its methyl ester (Bio-2) can enter cells
independently of the SLC5A6 transporter, which points to the presence of
alternative transport pathways. The biotin derivative Bio-1, which contains
p-aminophenylalanine, is internalized into cells solely
through the hSMVT transporter. The novel test system will serve as a tool for
investigating the pathways involved in vitamin entry into cells and for
developing therapeutic strategies for individuals with mutations in the
SLC5A6 gene, as well as other transport-related genes.