乳糖酶在成年人中的多态性表达在信使核糖核酸水平受到调控。

The polymorphic expression of lactase in adults is regulated at the messenger RNA level.

作者信息

Fajardo O, Naim H Y, Lacey S W

机构信息

Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas.

出版信息

Gastroenterology. 1994 May;106(5):1233-41. doi: 10.1016/0016-5085(94)90014-0.

DOI:10.1016/0016-5085(94)90014-0

PMID:8174885

Abstract

BACKGROUND/AIMS: Lactase phlorizin hydrolase (LPH) activity is high in infants but declines 80%-90% before adulthood in most mammals, including humans. However, 95% of whites show autosomal dominant inheritance of a lifelong high lactose digesting capacity (LDC). This study attempted to clarify the molecular mechanism(s) of this phenomenon (posttranslational vs. pretranslational).

METHODS

A race- and sex-balanced cohort (n = 20) was studied, and lactose tolerance and levels of jejunal lactase protein, activity, and messenger RNA (mRNA) were measured.

RESULTS

These data confirm that black heritage predicts low LDC, and white heritage predicts high LDC. Lactase breath hydrogen and determination of lactase/sucrase ratio (L/S) from jejunal biopsy specimens divide the group by high and low LDC phenotypes concordantly. All subjects with an L/S ratio > 0.5 had immunodetectable LPH protein and measurably higher LPH mRNA levels than the remaining subjects. LPH mRNA levels are highly correlated with lactase specific activity (r = 0.80) and L/S ratio (r = 0.88).

CONCLUSIONS

The direct correlation between LPH mRNA levels and lactase expression argues that the gene responsible for the human lactase polymorphism regulates the level of LPH mRNA.

摘要

背景/目的：乳糖酶-根皮苷水解酶（LPH）活性在婴儿期较高，但在包括人类在内的大多数哺乳动物成年前会下降80%-90%。然而，95%的白人表现出终身高乳糖消化能力（LDC）的常染色体显性遗传。本研究试图阐明这一现象的分子机制（翻译后与翻译前）。

方法

对一个种族和性别均衡的队列（n = 20）进行了研究，并测量了乳糖耐受性以及空肠乳糖酶蛋白、活性和信使核糖核酸（mRNA）水平。

结果

这些数据证实，黑人血统预示着低LDC，而白人血统预示着高LDC。乳糖呼气氢检测以及空肠活检标本中乳糖酶/蔗糖酶比值（L/S）的测定将该组分为高LDC和低LDC表型，结果一致。所有L/S比值> 0.5的受试者均能通过免疫检测到LPH蛋白，且其LPH mRNA水平明显高于其余受试者。LPH mRNA水平与乳糖酶比活性（r = 0.80）和L/S比值（r = 0.88）高度相关。