Mutations in <i>MAPKBP1</i> Cause Juvenile or Late-Onset Cilia-Independent Nephronophthisis

Macia, Maxence S.,Halbritter, Jan,Delous, Marion,Bredrup, Cecilie,Gutter, Arthur,Filhol, Emilie,Mellgren, Anne E.C.,Leh, Sabine,Bizet, Albane,Braun, Daniela A.,Gee, Heon Y.,Silbermann, Flora,Henry, Ch University of Chicago Press [etc.] 2017 American journal of human genetics Vol.100 No.2

<P>Nephronophthisis (NPH), an autosomal-recessive tubulointerstitial nephritis, is the most common cause of hereditary end-stage renal disease in the first three decades of life. Since most NPH gene products (NPHP) function at the primary cilium, NPH is classified as a ciliopathy. We identified mutations in a candidate gene in eight individuals from five families presenting late-onset NPH with massive renal fibrosis. This gene encodes MAPKBP1, a poorly characterized scaffolding protein for JNK signaling. Immunofluorescence analyses showed that MAPKBP1 is not present at the primary cilium and that fibroblasts from affected individuals did not display ciliogenesis defects, indicating that MAPKBP1 may represent a new family of NPHP not involved in cilia-associated functions. Instead, MAPKBP1 is recruited to mitotic spindle poles (MSPs) during the early phases of mitosis where it colocalizes with its paralog WDR62, which plays a key role at MSP. Detected mutations compromise recruitment of MAPKBP1 to the MSP and/or its interaction with JNK2 or WDR62. Additionally, we show increased DNA damage response signaling in fibroblasts from affected individuals and upon knockdown of <I>Mapkbp1</I> in murine cell lines, a phenotype previously associated with NPH. In conclusion, we identified mutations in <I>MAPKBP1</I> as a genetic cause of juvenile or late-onset and cilia-independent NPH.</P>

Mutations of <i>ADAMTS9</i> Cause Nephronophthisis-Related Ciliopathy

Choi, Yo Jun,Halbritter, Jan,Braun, Daniela A.,Schueler, Markus,Schapiro, David,Rim, John Hoon,Nandadasa, Sumeda,Choi, Won-il,Widmeier, Eugen,Shril, Shirlee,Kö,rber, Friederike,Sethi, Sidharth K. Elsevier 2019 American journal of human genetics Vol.104 No.1

<P>Nephronophthisis-related ciliopathies (NPHP-RCs) are a group of inherited diseases that are associated with defects in primary cilium structure and function. To identify genes mutated in NPHP-RC, we performed homozygosity mapping and whole-exome sequencing for >100 individuals, some of whom were single affected individuals born to consanguineous parents and some of whom were siblings of indexes who were also affected by NPHP-RC. We then performed high-throughput exon sequencing in a worldwide cohort of 800 additional families affected by NPHP-RC. We identified two <I>ADAMTS9</I> mutations (c.4575_4576del [p.Gln1525Hisfs<SUP>∗</SUP>60] and c.194C>G [p.Thr65Arg]) that appear to cause NPHP-RC. Although ADAMTS9 is known to be a secreted extracellular metalloproteinase, we found that ADAMTS9 localized near the basal bodies of primary cilia in the cytoplasm. Heterologously expressed wild-type ADAMTS9, in contrast to mutant proteins detected in individuals with NPHP-RC, localized to the vicinity of the basal body. Loss of ADAMTS9 resulted in shortened cilia and defective sonic hedgehog signaling. Knockout of <I>Adamts9</I> in IMCD3 cells, followed by spheroid induction, resulted in defective lumen formation, which was rescued by an overexpression of wild-type, but not of mutant, ADAMTS9. Knockdown of <I>adamts9</I> in zebrafish recapitulated NPHP-RC phenotypes, including renal cysts and hydrocephalus. These findings suggest that the identified mutations in <I>ADAMTS9</I> cause NPHP-RC and that ADAMTS9 is required for the formation and function of primary cilia.</P>

Mutations in SLC26A1 Cause Nephrolithiasis

Gee, H.Y.,Jun, I.,Braun, D.A.,Lawson, J.A.,Halbritter, J.,Shril, S.,Nelson, C.P.,Tan, W.,Stein, D.,Wassner, A.J.,Ferguson, M.A.,Gucev, Z.,Sayer, J.A.,Milosevic, D.,Baum, M.,Tasic, V.,Lee, M.G.,Hildebr University of Chicago Press [etc.] 2016 American journal of human genetics Vol.98 No.6

<P>Nephrolithiasis, a condition in which urinary supersaturation leads to stone formation in the urinary system, affects about 5%-10% of individuals worldwide at some point in their lifetime and results in significant medical costs and morbidity. To date, mutations in more than 30 genes have been described as being associated with nephrolithiasis, and these mutations explain about 15% of kidney stone cases, suggesting that additional nephrolithiasis-associated genes remain to be discovered. To identify additional genes whose mutations are linked to nephrolithiasis, we performed targeted next-generation sequencing of 18 hypothesized candidate genes in 348 unrelated individuals with kidney stones. We detected biallelic mutations in SLC26A1 (solute carrier family 26 member 1) in two unrelated individuals with calcium oxalate kidney stones. We show by immunofluorescence, immunoblotting, and glycosylation analysis that the variant protein mimicking p.Thr185Met has defects in protein folding or trafficking. In addition, by measuring anion exchange activity of SLC26A1, we demonstrate that all the identified mutations in SLC26A1 result in decreased transporter activity. Our data identify SLC26A1 mutations as causing a recessive Mendelian form of nephrolithiasis.</P>

Prevalence of Monogenic Causes in Pediatric Patients with Nephrolithiasis or Nephrocalcinosis

Braun, Daniela Anne,Lawson, Jennifer Ashley,Gee, Heon Yung,Halbritter, Jan,Shril, Shirlee,Tan, Weizhen,Stein, Deborah,Wassner, Ari J.,Ferguson, Michael A.,Gucev, Zoran,Fisher, Brittany,Spaneas, Leslie American Society of Nephrology 2016 CLINICAL JOURNAL- AMERICAN SOCIETY OF NEPHROLOGY Vol.11 No.4

<P>Background and objectives Nephrolithiasis is a prevalent condition that affects 10%-15% of adults in their lifetime. It is associated with high morbidity due to colicky pain, the necessity for surgical intervention, and sometimes progression to CKD. In recent years, multiple monogenic causes of nephrolithiasis and nephrocalcinosis have been identified. However, the prevalence of each monogenic gene in a pediatric renal stone cohort has not yet been extensively studied. Design, setting, participants, & measurements To determine the percentage of cases that can be explained molecularly by mutations in one of 30 known nephrolithiasis/nephrocalcinosis genes, we conducted a high-throughput exon sequencing analysis in an international cohort of 143 individuals <18 years of age, with nephrolithiasis (n=123) or isolated nephrocalcinosis (n=20). Over 7 months, all eligible individuals at three renal stone clinics in the United States and Europe were approached for study participation. Results We detected likely causative mutations in 14 of 30 analyzed genes, leading to a molecular diagnosis in 16.8% (24 of 143) of affected individuals; 12 of the 27 detected mutations were not previously described as disease causing (44.4%). We observed that in our cohort all individuals with infantile manifestation of nephrolithiasis or nephrocalcinosis had causative mutations in recessive rather than dominant monogenic genes. In individuals who manifested later in life, causative mutations in dominant genes were more frequent. Conclusions We present the first exclusively pediatric cohort examined for monogenic causes of nephrolithiasis/nephrocalcinosis, and suggest that important therapeutic and preventative measures may result from mutational analysis in individuals with early manifestation of nephrolithiasis or nephrocalcinosis.</P>

Mutations of CEP83 Cause Infantile Nephronophthisis and Intellectual Disability

Failler, M.,Gee, H.,Krug, P.,Joo, K.,Halbritter, J.,Belkacem, L.,Filhol, E.,Porath, Jonathan D.,Braun, Daniela A.,Schueler, M.,Frigo, A.,Alibeu, O.,Masson, C.,Brochard, K.,Hurault de Ligny, B.,Novo, R University of Chicago Press [etc.] 2014 American journal of human genetics Vol.94 No.6

Ciliopathies are a group of hereditary disorders associated with defects in cilia structure and function. The distal appendages (DAPs) of centrioles are involved in the docking and anchoring of the mother centriole to the cellular membrane during ciliogenesis. The molecular composition of DAPs was recently elucidated and mutations in two genes encoding DAPs components (CEP164/NPHP15, SCLT1) have been associated with human ciliopathies, namely nephronophthisis and orofaciodigital syndrome. To identify additional DAP components defective in ciliopathies, we independently performed targeted exon sequencing of 1,221 genes associated with cilia and 5 known DAP protein-encoding genes in 1,255 individuals with a nephronophthisis-related ciliopathy. We thereby detected biallelic mutations in a key component of DAP-encoding gene, CEP83, in seven families. All affected individuals had early-onset nephronophthisis and four out of eight displayed learning disability and/or hydrocephalus. Fibroblasts and tubular renal cells from affected individuals showed an altered DAP composition and ciliary defects. In summary, we have identified mutations in CEP83, another DAP-component-encoding gene, as a cause of infantile nephronophthisis associated with central nervous system abnormalities in half of the individuals.

Cultured cambial meristematic cells as a source of plant natural products

Lee, Eun-Kyong,Jin, Young-Woo,Park, Joong Hyun,Yoo, Young Mi,Hong, Sun Mi,Amir, Rabia,Yan, Zejun,Kwon, Eunjung,Elfick, Alistair,Tomlinson, Simon,Halbritter, Florian,Waibel, Thomas,Yun, Byung-Wook,Loak Nature Publishing Group, a division of Macmillan P 2010 Nature biotechnology Vol.28 No.11

A plethora of important, chemically diverse natural products are derived from plants. In principle, plant cell culture offers an attractive option for producing many of these compounds. However, it is often not commercially viable because of difficulties associated with culturing dedifferentiated plant cells (DDCs) on an industrial scale. To bypass the dedifferentiation step, we isolated and cultured innately undifferentiated cambial meristematic cells (CMCs). Using a combination of deep sequencing technologies, we identified marker genes and transcriptional programs consistent with a stem cell identity. This notion was further supported by the morphology of CMCs, their hypersensitivity to 款-irradiation and radiomimetic drugs and their ability to differentiate at high frequency. Suspension culture of CMCs derived from Taxus cuspidata, the source of the key anticancer drug, paclitaxel (Taxol), circumvented obstacles routinely associated with the commercial growth of DDCs. These cells may provide a cost-effective and environmentally friendly platform for sustainable production of a variety of important plant natural products.