Targeted deletion of the AAA-ATPase Ruvbl1 in mice disrupts ciliary integrity and causes renal disease and hydrocephalus

Abstract

Ciliopathies comprise a large number of hereditary human diseases and syndromes caused by mutations resulting in dysfunction of either primary or motile cilia. Both types of cilia share a similar architecture. While primary cilia are present on most cell types, expression of motile cilia is limited to specialized tissues utilizing ciliary motility. We characterized protein complexes of ciliopathy proteins and identified the conserved AAA-ATPase Ruvbl1 as a common novel component. Here, we demonstrate that Ruvbl1 is crucial for the development and maintenance of renal tubular epithelium in mice: both constitutive and inducible deletion in tubular epithelial cells result in renal failure with tubular dilatations and fewer ciliated cells. Moreover, inducible deletion of Ruvbl1 in cells carrying motile cilia results in hydrocephalus, suggesting functional relevance in both primary and motile cilia. Cilia of Ruvbl1-negative cells lack crucial proteins, consistent with the concept of Ruvbl1-dependent cytoplasmic pre-assembly of ciliary protein complexes.

Role of the Novel Hsp90 Co-Chaperones in Dynein Arms’ Preassembly

“…Although the levels of transcription in many components that build the dynein arms were unchanged [15,48], the transmission electron microscopy (TEM) analysis showed that, in both mutants, cilia had a reduced number of ODAs and IDAs [15]. Immunofluorescence analysis of mouse ependymal and oviduct epithelial multiciliated cells, as well as studies of Kupffer's vesicle and pronephric ciliated cells in zebrafish, showed that RuvBL1 was present in the cytoplasm [15,49] and in the nucleus [49]. Contradictory to these data, using a non-commercial antibody, it was shown that in Chlamydomonas RuvBL1 was also present in flagella [50].…”

“…In transgenic RuvBL1 frt-fl mice disruption of ciliary integrity was observed, causing renal disease and hydrocephalus [49]. In mice, loss-of-function mutations of RuvBL1 is lethal at an early embryonic stage, but deletion of the RuvBL1 only in premeiotic male germ cells causes male infertility [15].…”

“…In mice, loss-of-function mutations of RuvBL1 is lethal at an early embryonic stage, but deletion of the RuvBL1 only in premeiotic male germ cells causes male infertility [15]. A reduction and/or lack of DNAH9 (Dynein heavy chain), DNAI2 (Dynein intermediate chain), and DNALI1 (light intermediate chain-1) in sperm flagella and cilia of multiciliated cells suggest the possible involvement of RuvBL1 in dynein arms' preassembly or stability [15,49]. Interestingly, the co-immunoprecipitation analyses (from testis of mutant mice) revealed that when RubBL1 was mutated, both RuvBL1-RuvBL2-Hsp90 and DNAI1-DNAI2 complexes failed to form.…”

DLG5 variants are associated with multiple congenital anomalies including ciliopathy phenotypes

“…6 Thus, ciliary dysfunction may differentially affect a variety of tissues including the brain, retina, heart, respiratory tract, skeleton, kidneys and urogenital tract. [7][8][9][10][11][12][13][14] As a consequence, dysfunction of different ciliarelated genes can cause remarkably different phenotypes across different tissues. Although several monogenic causes of ciliopathies have been identified, 15 different alleles of the same gene can also cause strikingly diverse disease phenotypes.…”

Targeted deletion of Ruvbl1 results in severe defects of epidermal development and perinatal mortality

“…In addition, the Ruvbl proteins or protein complexes involving the Ruvbl proteins modulate transcriptional activity of, e.g., pro-proliferative factors like MYC and ß-catenin and play important roles in multiple steps of cell cycle progression and cellular metabolism [ 6 , 8 , 13 ]. We recently identified Ruvbl1 as a component of ciliary protein complexes in renal tubular, bronchial, and ependymal epithelial cells [ 15 ]. Ruvbl1 also seems to be essential for early embryogenesis in mice [ 15 , 16 ], and it has been suggested that loss of murine stem cell populations may be due to apoptosis [ 16 ].…”