THAP11_F80Lcobalamin disorder-associated mutation reveals normal and pathogenic THAP11 functions in gene expression and cell proliferation

Abstract

27 Twelve human THAP proteins share the THAP domain, an evolutionary conserved zinc-finger 28 DNA-binding domain. Studies of different THAP proteins have indicated roles in gene 29 transcription, cell proliferation and development. We have analyzed this protein family, 30 focusing on THAP7 and THAP11. We show that human THAP proteins possess differing homo-31 and heterodimer formation properties and interaction abilities with the transcriptional co-32 regulator HCF-1. HEK-293 cells lacking THAP7 were viable but proliferated more slowly. In 33 contrast, HEK-293 cells were very sensitive to THAP11 alteration. Nevertheless, HEK-293 cells 34 bearing a THAP11 mutation identified in a patient suffering from cobalamin disorder 35 (THAP11 F80L ) were viable although proliferated more slowly. Cobalamin disorder is an inborn 36 vitamin deficiency characterized by neurodevelopmental abnormalities, most often owing to 37 biallelic mutations in the MMACHC gene, whose gene product MMACHC is a key enzyme in 38 the cobalamin (vitamin B 12 ) metabolic pathway. We show that THAP11 F80L selectively affected 39 promoter binding by THAP11, having more deleterious effects on a subset of THAP11 targets, 40 and resulting in altered patterns of gene expression. In particular, THAP11 F80L exhibited a 41 strong effect on association with the MMACHC promoter and led to a decrease in MMACHC 42 gene transcription, suggesting that the THAP11 F80L mutation is directly responsible for the 43 observed cobalamin disorder. 44 45 3 46 Introduction 47 48The THAP family of gene paralogs encodes 12 proteins in human, named THAP0 to 49 THAP11. These are defined by their N-terminal THAP (for Thanatos -referring to the Greek 50 God of Death -Associated Proteins) domain, an atypical zinc-finger DNA-binding domain 51 [1,2]. THAP domains display similar three-dimensional structures, while recognizing different 52 DNA target sequences [3-7]. Studies of different THAP proteins have indicated roles in gene 53 transcription, cell proliferation and development. Here, we focus on two members: THAP7 54 and THAP11. 55 THAP7 represses gene transcription, both by promoting histone deacetylation and by 56 masking histone tails from histone acetyltransferase complexes [8,9]. It is also implicated in 57 the control of cell proliferation by abrogating Histone Nuclear Factor P (HiNF-P)-mediated 58 activation of histone H4 gene transcription [10]. 59 THAP11 (known as Ronin in mice, [11]) also regulates mammalian cell proliferation, 60 with reported examples for both activation [11,12] and repression [13,14], and binds 61 numerous promoters of genes involved in cell growth, metabolism, and cell cycle [12-17]. It 62 also has essential transcriptional roles in pluripotency [11,18,19], hematopoiesis [20], and 63 early development of retina [21], heart [17], and brain [22]. Furthermore, THAP11 is 64 important for mitochondrial function by regulating nuclear mitochondrial-related genes, 65 including components of the electron transport chain [21]. Consistent with the frequent 66 ...