Exome Sequencing of SLC30A2 Identifies Novel Loss- and Gain-of-Function Variants Associated with Breast Cell Dysfunction

Samina Alam, Stephen R. Hennigar, Carla Gallagher, David I. Soybel, Shannon L. Kelleher

Research output: Contribution to journalReview article

18 Citations (Scopus)

Abstract

The zinc (Zn) transporter ZnT2 (SLC30A2) is expressed in specialized secretory cells including breast, pancreas and prostate, and imports Zn into mitochondria and vesicles. Mutations in SLC30A2 substantially reduce milk Zn concentration ([Zn]) and cause severe Zn deficiency in exclusively breastfed infants. Recent studies show that ZnT2-null mice have low milk [Zn], in addition to profound defects in mammary gland function during lactation. Here, we used breast milk [Zn] to identify novel non-synonymous ZnT2 variants in a population of lactating women. We also asked whether specific variants induce disturbances in intracellular Zn management or cause cellular dysfunction in mammary epithelial cells. Healthy, breastfeeding women were stratified into quartiles by milk [Zn] and exonic sequencing of SLC30A2 was performed. We found that 36 % of women tested carried non-synonymous ZnT2 variants, all of whom had milk Zn levels that were distinctly above or below those in women without variants. We identified 12 novel heterozygous variants. Two variants (D103E and T288S) were identified with high frequency (9 and 16 %, respectively) and expression of T288S was associated with a known hallmark of breast dysfunction (elevated milk sodium/potassium ratio). Select variants (A28D, K66N, Q71H, D103E, A105P, Q137H, T288S and T312K) were characterized in vitro. Compared with wild-type ZnT2, these variants were inappropriately localized, and most resulted in either ‘loss-of-function’ or ‘gain-of-function’, and altered sub-cellular Zn pools, Zn secretion, and cell cycle check-points. Our study indicates that SLC30A2 variants are common in this population, dysregulate Zn management and can lead to breast cell dysfunction. This suggests that genetic variation in ZnT2 could be an important modifier of infant growth/development and reproductive health/disease. Importantly, milk [Zn] level may serve as a bio-reporter of breast function during lactation.

Original languageEnglish (US)
Pages (from-to)159-172
Number of pages14
JournalJournal of mammary gland biology and neoplasia
Volume20
Issue number3-4
DOIs
StatePublished - Aug 21 2015

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Exome
Zinc
Breast
Milk
Lactation
Reproductive Health
Human Milk
Human Mammary Glands
Child Development
Breast Feeding
Growth and Development
Population

All Science Journal Classification (ASJC) codes

  • Oncology
  • Cancer Research

Cite this

@article{54c7f60a601b496fa54da8e9a0ba7146,
title = "Exome Sequencing of SLC30A2 Identifies Novel Loss- and Gain-of-Function Variants Associated with Breast Cell Dysfunction",
abstract = "The zinc (Zn) transporter ZnT2 (SLC30A2) is expressed in specialized secretory cells including breast, pancreas and prostate, and imports Zn into mitochondria and vesicles. Mutations in SLC30A2 substantially reduce milk Zn concentration ([Zn]) and cause severe Zn deficiency in exclusively breastfed infants. Recent studies show that ZnT2-null mice have low milk [Zn], in addition to profound defects in mammary gland function during lactation. Here, we used breast milk [Zn] to identify novel non-synonymous ZnT2 variants in a population of lactating women. We also asked whether specific variants induce disturbances in intracellular Zn management or cause cellular dysfunction in mammary epithelial cells. Healthy, breastfeeding women were stratified into quartiles by milk [Zn] and exonic sequencing of SLC30A2 was performed. We found that 36 {\%} of women tested carried non-synonymous ZnT2 variants, all of whom had milk Zn levels that were distinctly above or below those in women without variants. We identified 12 novel heterozygous variants. Two variants (D103E and T288S) were identified with high frequency (9 and 16 {\%}, respectively) and expression of T288S was associated with a known hallmark of breast dysfunction (elevated milk sodium/potassium ratio). Select variants (A28D, K66N, Q71H, D103E, A105P, Q137H, T288S and T312K) were characterized in vitro. Compared with wild-type ZnT2, these variants were inappropriately localized, and most resulted in either ‘loss-of-function’ or ‘gain-of-function’, and altered sub-cellular Zn pools, Zn secretion, and cell cycle check-points. Our study indicates that SLC30A2 variants are common in this population, dysregulate Zn management and can lead to breast cell dysfunction. This suggests that genetic variation in ZnT2 could be an important modifier of infant growth/development and reproductive health/disease. Importantly, milk [Zn] level may serve as a bio-reporter of breast function during lactation.",
author = "Samina Alam and Hennigar, {Stephen R.} and Carla Gallagher and Soybel, {David I.} and Kelleher, {Shannon L.}",
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Exome Sequencing of SLC30A2 Identifies Novel Loss- and Gain-of-Function Variants Associated with Breast Cell Dysfunction. / Alam, Samina; Hennigar, Stephen R.; Gallagher, Carla; Soybel, David I.; Kelleher, Shannon L.

In: Journal of mammary gland biology and neoplasia, Vol. 20, No. 3-4, 21.08.2015, p. 159-172.

Research output: Contribution to journalReview article

TY - JOUR

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AU - Alam, Samina

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AU - Kelleher, Shannon L.

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N2 - The zinc (Zn) transporter ZnT2 (SLC30A2) is expressed in specialized secretory cells including breast, pancreas and prostate, and imports Zn into mitochondria and vesicles. Mutations in SLC30A2 substantially reduce milk Zn concentration ([Zn]) and cause severe Zn deficiency in exclusively breastfed infants. Recent studies show that ZnT2-null mice have low milk [Zn], in addition to profound defects in mammary gland function during lactation. Here, we used breast milk [Zn] to identify novel non-synonymous ZnT2 variants in a population of lactating women. We also asked whether specific variants induce disturbances in intracellular Zn management or cause cellular dysfunction in mammary epithelial cells. Healthy, breastfeeding women were stratified into quartiles by milk [Zn] and exonic sequencing of SLC30A2 was performed. We found that 36 % of women tested carried non-synonymous ZnT2 variants, all of whom had milk Zn levels that were distinctly above or below those in women without variants. We identified 12 novel heterozygous variants. Two variants (D103E and T288S) were identified with high frequency (9 and 16 %, respectively) and expression of T288S was associated with a known hallmark of breast dysfunction (elevated milk sodium/potassium ratio). Select variants (A28D, K66N, Q71H, D103E, A105P, Q137H, T288S and T312K) were characterized in vitro. Compared with wild-type ZnT2, these variants were inappropriately localized, and most resulted in either ‘loss-of-function’ or ‘gain-of-function’, and altered sub-cellular Zn pools, Zn secretion, and cell cycle check-points. Our study indicates that SLC30A2 variants are common in this population, dysregulate Zn management and can lead to breast cell dysfunction. This suggests that genetic variation in ZnT2 could be an important modifier of infant growth/development and reproductive health/disease. Importantly, milk [Zn] level may serve as a bio-reporter of breast function during lactation.

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