Mutations in THAP11 cause an inborn error of cobalamin metabolism and developmental abnormalities

Abstract

CblX (MIM309541) is an X-linked recessive disorder characterized by defects in cobalamin (vitamin B12) metabolism and other developmental defects. Mutations in HCFC1, a transcriptional co-regulator which interacts with multiple transcription factors, have been associated with cblX. HCFC1 regulates cobalamin metabolism via the regulation of MMACHC expression through its interaction with THAP11, a THAP domain-containing transcription factor. The HCFC1/THAP11 complex potentially regulates genes involved in diverse cellular functions including cell cycle, proliferation, and transcription. Thus, it is likely that mutation of THAP11 also results in biochemical and other phenotypes similar to those observed in patients with cblX. We report a patient who presented with clinical and biochemical phenotypic features that overlap cblX, but who does not have any mutations in either MMACHC or HCFC1. We sequenced THAP11 by Sanger sequencing and discovered a potentially pathogenic, homozygous variant, c.240C > G (p.Phe80Leu). Functional analysis in the developing zebrafish embryo demonstrated that both THAP11 and HCFC1 regulate the proliferation and differentiation of neural precursors, suggesting important roles in normal brain development. The loss of THAP11 in zebrafish embryos results in craniofacial abnormalities including the complete loss of Meckel's cartilage, the ceratohyal, and all of the ceratobranchial cartilages. These data are consistent with our previous work that demonstrated a role for HCFC1 in vertebrate craniofacial development. High throughput RNA-sequencing analysis reveals several overlapping gene targets of HCFC1 and THAP11. Thus, both HCFC1 and THAP11 play important roles in the regulation of cobalamin metabolism as well as other pathways involved in early vertebrate development.

THAP11F80Lcobalamin disorder-associated mutation reveals normal and pathogenic THAP11 functions in gene expression and cell proliferation

“…During the course of this study, a human THAP11 mutation was identified in a patient with cobalamin disorder [22]. We thus took advantage of this finding to focus, as we do in the remainder of this study, on the clarification of the functional consequences of this cobalamin-disorder-associated THAP11 F80L mutation.…”

“…We thus took advantage of this finding to focus, as we do in the remainder of this study, on the clarification of the functional consequences of this cobalamin-disorder-associated THAP11 F80L mutation. The THAP11 F80 phenylalanine residue is highly conserved across vertebrate species [22] and also among the 12 different human THAP proteins (S1 Fig). As labeled in blue in S1 Fig, it is at the last position of the so-called “AVPTI F ” box (green box in S1 Fig) lying at the C terminus of the THAP-domain; this box has been suggested to promote proper folding of the DNA-binding zinc finger [3,4].…”

“…THAP11 (known as Ronin in mice, [11]) also regulates mammalian cell proliferation, with reported examples for both activation [11,12] and repression [13,14], and binds numerous promoters of genes involved in cell growth, metabolism, and cell cycle [12–17]. It also has essential transcriptional roles in pluripotency [11,18,19], hematopoiesis [20], and early development of retina [21], heart [17], and brain [22]. Furthermore, THAP11 is important for mitochondrial function by regulating nuclear mitochondrial-related genes, including components of the electron transport chain [21].…”

“…Furthermore, THAP11 is important for mitochondrial function by regulating nuclear mitochondrial-related genes, including components of the electron transport chain [21]. Consistent with the frequent involvement of THAP proteins in human diseases (e.g., dystonia 6 (THAP1, [23–25]), heart disease (THAP5, [26]), or cancers [7,12–14,27–32]), a THAP11 missense mutation is associated with cobalamin disorder, an inborn vitamin deficiency characterized by neurodevelopmental abnormalities [22].…”

SCA4 locus-associated gene Ronin (Thap11) increases Ataxin-1 protein levels and induces cerebellar degeneration in a mouse model of ataxia

“…The DNA recognition sequence of Ronin is frequently found in chromatin loop anchors (Bailey et al, 2015), making it conceivable that some of its actions may be exerted through changes in the 3D genomic organization of promoters. Ronin's gene regulation and DNA recognition sequence have been critically linked to heart development (Fujita et al, 2027), retina development (Poche et al, 2016) and disease (Radziwon et al, 2017) as well as cobalamin metabolism (Quintana et al, 2017). Additionally, polyglutamine proteins such as Ronin have recently been associated with the assembly of functional units (e.g., Pol II) through a biophysical process called phase separation (Toretsky and Wright, 2014).…”