Reversal of left-right asymmetry: a situs inversus mutation

Finding of situs inversus in endoscopic sleeve gastroplasty: Case report

INTRODUCTION AND IMPORTANCE

Situs inversus is an anatomical rare condition in which visceral organs are not located in its normal position, with a reversal anatomical orientation.

CASE PRESENTATION

We present a case of an 27-year-old male with a Body Mass Index (BMI) of 36.02 Kg/m2, who was programed for a Endoscopic Sleeve Gastroplasty (ESG), in which Situs inversus was documented.

CLINICAL DISCUSSION

Situs inversus is an uncommon anatomical condition that complicates identifying surgical landmarks and performing procedures like ESG. Preoperative imaging, such as abdominal ultrasound or computed tomography, is critical for confirming the diagnosis and planning the intervention. In this case, ESG was successfully executed using standard techniques, emphasizing the importance of expertise and careful planning. The reversed anatomy required adjustments in endoscopic navigation but did not necessitate major deviations from established protocols. This case highlights that, under the care of experienced endoscopists, ESG remains a safe and effective option for patients with situs inversus.

CONCLUSION

Situs inversus is rare anatomical variation that can represent a challenge in bariatric endoscopic procedures such as ESG. Nevertheless, ESG can be safely performed under an experienced endoscopic bariatric surgeon.

Large-scale genomic investigation of pediatric cholestasis reveals a novel hepatorenal ciliopathy caused by PSKH1 mutations

PURPOSE

Pediatric cholestasis is the phenotypic expression of clinically and genetically heterogeneous disorders of bile acid synthesis and flow. Although a growing number of monogenic causes of pediatric cholestasis have been identified, the majority of cases remain undiagnosed molecularly.

METHODS

In a cohort of 299 pediatric participants (279 families) with intrahepatic cholestasis, we performed exome sequencing as a first-tier diagnostic test.

RESULTS

A likely causal variant was identified in 135 families (48.56%). These comprise 135 families that harbor variants spanning 37 genes with established or tentative links to cholestasis. In addition, we propose a novel candidate gene (PSKH1) (HGNC:9529) in 4 families. PSKH1 was particularly compelling because of strong linkage in 3 consanguineous families who shared a novel hepatorenal ciliopathy phenotype. Two of the 4 families shared a founder homozygous variant, whereas the third and fourth had different homozygous variants in PSKH1. PSKH1 encodes a putative protein serine kinase of unknown function. Patient fibroblasts displayed abnormal cilia that are long and show abnormal transport. A homozygous Pskh1 mutant mouse faithfully recapitulated the human phenotype and displayed abnormally long cilia. The phenotype could be rationalized by the loss of catalytic activity observed for each recombinant PSKH1 variant using in vitro kinase assays.

CONCLUSION

Our results support the use of genomics in the workup of pediatric cholestasis and reveal PSKH1-related hepatorenal ciliopathy as a novel candidate monogenic form.

Dimerization activates the Inversin complex in C. elegans

Genetic, colocalization, and biochemical studies suggest that the ankyrin repeat-containing proteins Inversin (INVS) and ANKS6 function with the NEK8 kinase to control tissue patterning and maintain organ physiology. It is unknown whether these three proteins assemble into a static "Inversin complex" or one that adopts multiple bioactive forms. Through the characterization of hyperactive alleles in C. elegans, we discovered that the Inversin complex is activated by dimerization. Genome engineering of an RFP tag onto the nematode homologues of INVS (MLT-4) and NEK8 (NEKL-2) induced a gain-of-function, cyst-like phenotype that was suppressed by monomerization of the fluorescent tag. Stimulated dimerization of MLT-4 or NEKL-2 using optogenetics was sufficient to recapitulate the phenotype of a constitutively active Inversin complex. Further, dimerization of NEKL-2 bypassed a lethal MLT-4 mutant, demonstrating that the dimeric form is required for function. We propose that dynamic switching between at least two functionally distinct states - an active dimer and an inactive monomer - gates the output of the Inversin complex.

BMP4 regulates asymmetric Pkd2 distribution in mouse nodal immotile cilia and ciliary mechanosensing required for left-right determination

BACKGROUND

Mouse nodal immotile cilia mechanically sense the bending direction for left-right (L-R) determination and activate the left-side-specific signaling cascade, leading to increased Nodal activity. Asymmetric distribution of Pkd2, a crucial channel for L-R determination, on immotile cilia has been reported recently. However, the causal relationship between the asymmetric Pkd2 distribution and direction-dependent flow sensing is not well understood. Furthermore, the underlying molecular mechanism directing this asymmetric Pkd2 distribution remains unclear.

RESULTS

The effects of several recombinant proteins and inhibitors on the Pkd2 distribution were analyzed using super-resolution microscopy. Notably, bone morphogenetic protein 4 (BMP4) affected the Pkd2 distribution. Additionally, three-dimensional manipulation of nodal immotile cilia using optical tweezers revealed that excess BMP4 caused defects in the mechanosensing ability of the cilia.

CONCLUSIONS

Experimental data together with model calculations suggest that BMP4 regulates the asymmetric distribution of Pkd2 in nodal immotile cilia, thereby affecting the ability of these cilia to sense the bending direction for L-R determination. This study, for the first time, provides insight into the relationship between the asymmetric protein distribution in cilia and their function.

Inversin-deficient (inv) mice do not establish a polarized duct system in the liver and pancreas

Inversin-deficient (inv) mice have anomalies in liver and pancreatic development in addition to an inverted left-right axis of the body. The present study was undertaken to unveil mechanisms of bile and pancreatic duct development from immunohistochemical analyses of anomalies in inv mice. Intrahepatic bile ducts having proximodistal polarity in size and the height of their epithelia, and ductules were formed in livers of wild-type neonates. By contrast, in inv mice, ductal plates, precursor structures of intrahepatic bile ducts and ductules, persisted without the proximodistal polarity. Their epithelial cells did not acquire planar cell polarity (PCP) in terms of expression of tight junction proteins although they expressed bile duct markers, HNF1β and SOX9. They had an apicobasal polarity from expression of basal laminar components. Enlargement of the hepatic artery and poor connective tissue development, including the abnormal deposition of the extracellular matrices, were also noted in inv mice, suggesting that bile duct development was coupled to that of the hepatic artery and portal vein. In pancreata of inv neonates, neither the main pancreatic duct was formed, nor dilated duct-like structures had the morphological polarity from the connecting point with the common bile duct. Lumina of acini was dilated, and centroacinar cells changed their position in the acini to their neck region. Immunohistochemical analyses of tight junction proteins suggested that epithelial cells of the duct-like structures did not have a PCP. Thus, Invs may be required for the establishment of the PCP of the whole duct system in the liver and pancreas.

Dimerization activates the Inversin complex in C. elegans

Genetic, colocalization, and biochemical studies suggest that the ankyrin repeat-containing proteins Inversin (INVS) and ANKS6 function with the NEK8 kinase to control tissue patterning and maintain organ physiology. It is unknown whether these three proteins assemble into a static "Inversin complex" or one that adopts multiple bioactive forms. Through characterization of hyperactive alleles in C. elegans , we discovered that the Inversin complex is activated by dimerization. Genome engineering of an RFP tag onto the nematode homologs of INVS (MLT-4) and NEK8 (NEKL-2) induced a gain-of-function, cyst-like phenotype that was suppressed by monomerization of the fluorescent tag. Stimulated dimerization of MLT-4 or NEKL-2 using optogenetics was sufficient to recapitulate the phenotype of a constitutively active Inversin complex. Further, dimerization of NEKL-2 bypassed a lethal MLT-4 mutant, demonstrating that the dimeric form is required for function. We propose that dynamic switching between at least two functionally distinct states-an active dimer and an inactive monomer-gates the output of the Inversin complex.

Complete Common Bile Duct Injury after Laparoscopic Cholecystectomy in Situs Inversus Totalis: A Case Report, Review of the Literature and Illustrative Case Video

INTRODUCTION AND IMPORTANCE

Situs Inversus Totalis (SIT) is a rare condition characterized by the transposition of internal organs. Given the anatomical variations in SIT, surgeons must exercise extreme caution when performing laparoscopic cholecystectomy to avoid iatrogenic bile duct injury. Despite the high difficulty index associated with laparoscopic cholecystectomy in SIT, there is only one case report of common bile duct (CBD) injury in the English-language literature.

CASE PRESENTATION

A 41-year-old female patient, known to have Kartagener syndrome, underwent laparoscopic cholecystectomy for acute cholecystitis and was discharged home on post-operative day one. However, on post-operative day five, the patient presented to the emergency room with abdominal pain, fever, and jaundice. Laboratory tests revealed leukocytosis and hyperbilirubinemia. Radiological images revealed complete occlusion of the CBD. A delayed approach was chosen, and six weeks after her initial operation, a hepaticojejunostomy was performed.

CLINICAL DISCUSSION

Laparoscopic cholecystectomy is the standard operative procedure for gallbladder disease. The unique anatomy of SIT increases the risk of CBD injury during laparoscopic cholecystectomy. Surgeons are required to perform a mirror-image procedure and adhere to the basic principles of safe laparoscopic cholecystectomy in SIT. This is only the second reported case of CBD injury in SIT patients.

CONCLUSION

Laparoscopic cholecystectomy in SIT presents a significant challenge. In patients with SIT, preventing CBD injury is the best approach, and referral to an experienced hepato-pancreato-biliary (HPB) surgeon is recommended. A delayed approach to CBD injuries in SIT allows thorough planning and understanding of the complex anatomical variations in these patients.

Functions of cilia in cardiac development and disease

Errors in embryonic cardiac development are a leading cause of congenital heart defects (CHDs), including morphological abnormalities of the heart that are often detected after birth. In the past few decades, an emerging role for cilia in the pathogenesis of CHD has been identified, but this topic still largely remains an unexplored area. Mouse forward genetic screens and whole exome sequencing analysis of CHD patients have identified enrichment for de novo mutations in ciliary genes or non-ciliary genes, which regulate cilia-related pathways, linking cilia function to aberrant cardiac development. Key events in cardiac morphogenesis, including left-right asymmetric development of the heart, are dependent upon cilia function. Cilia dysfunction during left-right axis formation contributes to CHD as evidenced by the substantial proportion of heterotaxy patients displaying complex CHD. Cilia-transduced signaling also regulates later events during heart development such as cardiac valve formation, outflow tract septation, ventricle development, and atrioventricular septa formation. In this review, we summarize the role of motile and non-motile (primary cilia) in cardiac asymmetry establishment and later events during heart development.

Fetal liver development and implications for liver disease pathogenesis

The metabolic, digestive and homeostatic roles of the liver are dependent on proper crosstalk and organization of hepatic cell lineages. These hepatic cell lineages are derived from their respective progenitors early in organogenesis in a spatiotemporally controlled manner, contributing to the liver's specialized and diverse microarchitecture. Advances in genomics, lineage tracing and microscopy have led to seminal discoveries in the past decade that have elucidated liver cell lineage hierarchies. In particular, single-cell genomics has enabled researchers to explore diversity within the liver, especially early in development when the application of bulk genomics was previously constrained due to the organ's small scale, resulting in low cell numbers. These discoveries have substantially advanced our understanding of cell differentiation trajectories, cell fate decisions, cell lineage plasticity and the signalling microenvironment underlying the formation of the liver. In addition, they have provided insights into the pathogenesis of liver disease and cancer, in which developmental processes participate in disease emergence and regeneration. Future work will focus on the translation of this knowledge to optimize in vitro models of liver development and fine-tune regenerative medicine strategies to treat liver disease. In this Review, we discuss the emergence of hepatic parenchymal and non-parenchymal cells, advances that have been made in in vitro modelling of liver development and draw parallels between developmental and pathological processes.

Inactivation of Invs/Nphp2 in renal epithelial cells drives infantile nephronophthisis like phenotypes in mouse

Nephronophthisis (NPHP) is a ciliopathy characterized by renal fibrosis and cyst formation, and accounts for a significant portion of end stage renal disease in children and young adults. Currently, no targeted therapy is available for this disease. INVS/NPHP2 is one of the over 25 NPHP genes identified to date. In mouse, global knockout of Invs leads to renal fibrosis and cysts. However, the precise contribution of different cell types and the relationship between epithelial cysts and interstitial fibrosis remains undefined. Here, we generated and characterized cell-type-specific knockout mouse models of Invs, investigated the impact of removing cilia genetically on phenotype severity in Invs mutants and evaluated the impact of the histone deacetylase inhibitor valproic acid (VPA) on Invs mutants. Epithelial-specific knockout of Invs in Invsflox/flox;Cdh16-Cre mutant mice resulted in renal cyst formation and severe stromal fibrosis, while Invsflox/flox;Foxd1-Cre mice, where Invs is deleted in stromal cells, displayed no observable phenotypes up to the young adult stage, highlighting a significant role of epithelial-stromal crosstalk. Further, increased cell proliferation and myofibroblast activation occurred early during disease progression and preceded detectable cyst formation in the Invsflox/flox;Cdh16-Cre kidney. Moreover, concomitant removal of cilia partially suppressed the phenotypes of the Invsflox/flox;Cdh16-Cre mutant kidney, supporting a significant interaction of cilia and Invs function in vivo. Finally, VPA reduced cyst burden, decreased cell proliferation and ameliorated kidney function decline in Invs mutant mice. Our results reveal the critical role of renal epithelial cilia in NPHP and suggest the possibility of repurposing VPA for NPHP treatment.

Successful management of ectopic kidney stones in a patient with situs inversus totalis: a rare case report

Background

Situs inversus totalis is a very rare congenital anatomical variation, in which all thoracic and abdominal organs are right-left inverted. This condition is associated with an increased risk of organ malformations including ectopic kidney, which is a very rare combination.

Case presentation

A 56-year-old male presented with colicky left iliac pain associated with nausea, vomiting, and irritative lower urinary symptoms. The patient has a medical history of recurrent lower urinary infections and a family history of situs inversus totalis. Radiological images demonstrated dextrocardia, situs inversus totalis of all the abdominal organs, and an ectopic pelvic kidney on the left side, with 4 stones inside it. Left nephrectomy was performed due to extensive renal damage. At discharge and during follow-up, the patient's condition was satisfactory and stable.

Conclusions

The ectopic kidney may present diagnostic and therapeutic challenges when associated with situs inversus.

Laparoscopic sleeve gastrectomy in a patient with Situs Inversus Totalis: A case report and literature review

Introduction

& Importance: Laparoscopic sleeve gastrectomy (LSG) is a widely accepted and effective bariatric surgery for achieving weight loss in patients with extreme obesity. Performing this surgical procedure in patients with congenital anatomical changes including situs inversus (SI) is a challenge for the surgical team. In this condition, the orientation of intra-abdominal organs is the mirror image of those in normal populations.

Case presentation

Herein, we present a 29-year-old female with situs inversus totalis who successfully underwent an LSG surgery with proper weight loss post-operatively and no early and late complications.

Clinical discussion

By reviewing the literature for patients with SI undergoing the same procedure, all patients achieved significant weight loss. Three out of nineteen cases experienced complications which were controlled without significant morbidity or mortality.

Conclusion: we concluded that LSG will be a safe and effective surgery for the treatment of extreme obesity in SI patients, if the condition is diagnosed preoperatively.

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Performing laparoscopic sleeve gastrectomy (LSG) in patients with situs inversus (SI) is a challenge for the surgical team.

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SI should be diagnosed prior to surgery to avoid prolonged surgery and lack of expertise.

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LSG will be a safe and effective surgery for the treatment of extreme obesity in SI patients.

Laparoscopic Sleeve Gastrectomy in a Patient With Situs Inversus Totalis and Kartagener Syndrome

Laparoscopic sleeve gastrectomy (LSG) is a widely accepted and adopted procedure to achieves weight loss in morbid obesity. Situs inversus (SI) is when the body's visceral organs are not in the normal position with reversal of anatomical orientation. Patients with obesity and SI can be challenging to diagnose and manage. We present a case of a 23-year-old male who has SI totalis with Kartagener syndrome who underwent LSG to treat morbid obesity. Furthermore, we conducted a comprehensive review of the current medical literature. We conclude that LSG can be safely performed in SI. However, it is recommended to leave such cases to more experienced surgeons. In addition, it is advisable to consider few unconventional technical operative methods before surgery. Nevertheless, more data are needed to better study LSG in SI patients, which can be difficult given the rare nature of SI.

Apical Restriction of the Planar Cell Polarity Component VANGL in Pancreatic Ducts Is Required to Maintain Epithelial Integrity

Cell polarity is essential for the architecture and function of numerous epithelial tissues. Here, we show that apical restriction of planar cell polarity (PCP) components is necessary for the maintenance of epithelial integrity. Using the mammalian pancreas as a model, we find that components of the core PCP pathway, such as the transmembrane protein Van Gogh-like (VANGL), become apically restricted over a period of several days. Expansion of VANGL localization to the basolateral membranes of progenitors leads to their death and disruption of the epithelial integrity. VANGL basolateral expansion does not affect apico-basal polarity but acts in the cells where Vangl is mislocalized by reducing Dishevelled and its downstream target ROCK. This reduction in ROCK activity culminates in progenitor cell egression, death, and eventually pancreatic hypoplasia. Thus, precise spatiotemporal modulation of VANGL-dependent PCP signaling is crucial for proper pancreatic morphogenesis.

Renal Ciliopathies: Sorting Out Therapeutic Approaches for Nephronophthisis

Nephronophthisis (NPH) is an autosomal recessive ciliopathy and a major cause of end-stage renal disease in children. The main forms, juvenile and adult NPH, are characterized by tubulointerstitial fibrosis whereas the infantile form is more severe and characterized by cysts. NPH is caused by mutations in over 20 different genes, most of which encode components of the primary cilium, an organelle in which important cellular signaling pathways converge. Ciliary signal transduction plays a critical role in kidney development and tissue homeostasis, and disruption of ciliary signaling has been associated with cyst formation, epithelial cell dedifferentiation and kidney function decline. Drugs have been identified that target specific signaling pathways (for example cAMP/PKA, Hedgehog, and mTOR pathways) and rescue NPH phenotypes in in vitro and/or in vivo models. Despite identification of numerous candidate drugs in rodent models, there has been a lack of clinical trials and there is currently no therapy that halts disease progression in NPH patients. This review covers the most important findings of therapeutic approaches in NPH model systems to date, including hypothesis-driven therapies and untargeted drug screens, approached from the pathophysiology of NPH. Importantly, most animal models used in these studies represent the cystic infantile form of NPH, which is less prevalent than the juvenile form. It appears therefore important to develop new models relevant for juvenile/adult NPH. Alternative non-orthologous animal models and developments in patient-based in vitro model systems are discussed, as well as future directions in personalized therapy for NPH.

The twists and turns of left-right asymmetric gut morphogenesis

Many organs develop left-right asymmetric shapes and positions that are crucial for normal function. Indeed, anomalous laterality is associated with multiple severe birth defects. Although the events that initially orient the left-right body axis are beginning to be understood, the mechanisms that shape the asymmetries of individual organs remain less clear. Here, we summarize new evidence challenging century-old ideas about the development of stomach and intestine laterality. We compare classical and contemporary models of asymmetric gut morphogenesis and highlight key unanswered questions for future investigation.

Molecular and cellular basis of left-right asymmetry in vertebrates

Although the human body appears superficially symmetrical with regard to the left-right (L-R) axis, most visceral organs are asymmetric in terms of their size, shape, or position. Such morphological asymmetries of visceral organs, which are essential for their proper function, are under the control of a genetic pathway that operates in the developing embryo. In many vertebrates including mammals, the breaking of L-R symmetry occurs at a structure known as the L-R organizer (LRO) located at the midline of the developing embryo. This symmetry breaking is followed by transfer of an active form of the signaling molecule Nodal from the LRO to the lateral plate mesoderm (LPM) on the left side, which results in asymmetric expression of Nodal (a left-side determinant) in the left LPM. Finally, L-R asymmetric morphogenesis of visceral organs is induced by Nodal-Pitx2 signaling. This review will describe our current understanding of the mechanisms that underlie the generation of L-R asymmetry in vertebrates, with a focus on mice.

New insights into ion channel-dependent signalling during left-right patterning

The left-right organizer (LRO) in the mouse consists of pit cells within the depression, located at the end of the developing notochord, also known as the embryonic node and crown cells lining the outer periphery of the node. Cilia on pit cells are posteriorly tilted, rotate clockwise and generate leftward fluid flow. Primary cilia on crown cells are required to interpret the directionality of fluid movement and initiate flow-dependent gene transcription. Crown cells express PC1-L1 and PC2, which may form a heteromeric polycystin channel complex on primary cilia. It is still only poorly understood how fluid flow activates the ciliary polycystin complex. Besides polycystin channels voltage gated channels like HCN4 and KCNQ1 have been implicated in establishing asymmetry. How this electrical network of ion channels initiates left-sided signalling cascades and differential gene expression is currently only poorly defined.

Genetics in biliary atresia

PURPOSE OF REVIEW

Biliary atresia is a poorly understood deadly disease. Genetic predisposition factors are suspected albeit not firmly established. This review summarizes recent evidence of genetic alterations in biliary atresia.

RECENT FINDINGS

Whole-genome association studies in biliary atresia patients identified four distinct predisposition loci with four different genes potentially involved in the disease occurrence. Variations in these genes were searched for, but none were found in patients with biliary atresia suggesting complex mechanisms.

SUMMARY

Despite decades since its description and decades of intensive researches, cause of biliary atresia disease remains enigmatic. The inheritance of biliary atresia is not Mendelian. Genetic predisposition factor is one of the explored fields to explain biliary atresia pathogenicity. Biliary atresia has been associated with several inborn syndromes, chromosome anomalies, and gene polymorphisms in specific populations. Four predisposition loci encompassing genes relevant to the disease have been identified, but no pathogenic variations were found in biliary atresia patients. Few reported cases of isolated biliary atresia manifestation in the context of known genetic diseases suggest coincidental findings. Alternatives to classic genetic alterations are proposed to explain genetic predisposition in biliary atresia including noncoding and epigenetic factors. Biliary atresia is most likely related to complex traits making its genetic exploration challenging.

The nucleoside-diphosphate kinase NME3 associates with nephronophthisis proteins and is required for ciliary function during renal development

Nephronophthisis (NPH) is an autosomal recessive renal disease leading to kidney failure in children and young adults. The protein products of the corresponding genes (NPHPs) are localized in primary cilia or their appendages. Only about 70% of affected individuals have a mutation in one of 100 renal ciliopathy genes, and no unifying pathogenic mechanism has been identified. Recently, some NPHPs, including NIMA-related kinase 8 (NEK8) and centrosomal protein 164 (CEP164), have been found to act in the DNA-damage response pathway and to contribute to genome stability. Here, we show that NME/NM23 nucleoside-diphosphate kinase 3 (NME3) that has recently been found to facilitate DNA-repair mechanisms binds to several NPHPs, including NEK8, CEP164, and ankyrin repeat and sterile α motif domain-containing 6 (ANKS6). Depletion of nme3 in zebrafish and Xenopus resulted in typical ciliopathy-associated phenotypes, such as renal malformations and left-right asymmetry defects. We further found that endogenous NME3 localizes to the basal body and that it associates also with centrosomal proteins, such as NEK6, which regulates cell cycle arrest after DNA damage. The ciliopathy-typical manifestations of NME3 depletion in two vertebrate in vivo models, the biochemical association of NME3 with validated NPHPs, and its localization to the basal body reveal a role for NME3 in ciliary function. We conclude that mutations in the NME3 gene may aggravate the ciliopathy phenotypes observed in humans.

Tubular cell loss in early inv/nphp2 mutant kidneys represents a possible homeostatic mechanism in cortical tubular formation

Inversion of embryonic turning (inv) cystic mice develop multiple renal cysts and are a model for type II nephronophthisis (NPHP2). The defect of planar cell polarity (PCP) by oriented cell division was proposed as the underlying cellular phenotype, while abnormal cell proliferation and apoptosis occur in some polycystic kidney disease models. However, how these cystogenic phenotypes are linked and what is most critical for cystogenesis remain largely unknown. In particular, in early cortical cytogenesis in the inv mutant cystic model, it remains uncertain whether the increased proliferation index results from changes in cell cycle length or cell fate determination. To address tubular cell kinetics, doubling time and total number of tubular cells, as well as amount of genomic DNA (gDNA), were measured in mutant and normal control kidneys. Despite a significantly higher bromodeoxyuridine (BrdU)-proliferation index in the mutant, total tubular cell number and doubling time were unaffected. Unexpectedly, the mutant had tubular cell loss, characterized by a temporal decrease in tubular cells incorporating 5-ethynyl-2´-deoxyuridine (EdU) and significantly increased nuclear debris. Based on current data we established a new multi-population shift model in postnatal renal development, indicating that a few restricted tubular cell populations contribute to cortical tubular formation. As in the inv mutant phenotype, the model simulation revealed a large population of tubular cells with rapid cell cycling and tubular cell loss. The proposed cellular kinetics suggest not only the underlying mechanism of the inv mutant phenotype but also a possible renal homeostatic mechanism for tubule formation.

Use of gene-editing technology to introduce targeted modifications in pigs

Pigs are an important resource in agriculture and serve as a model for human diseases. Due to their physiological and anatomical similarities with humans, pigs can recapitulate symptoms of human diseases, making them a useful model in biomedicine. However, in the past pig models have not been widely used partially because of the difficulty in genetic modification. The lack of true embryonic stem cells in pigs forced researchers to utilize genetic modification in somatic cells and somatic cell nuclear transfer (SCNT) to generate genetically engineered (GE) pigs carrying site-specific modifications. Although possible, this approach is extremely inefficient and GE pigs born through this method often presented developmental defects associated with the cloning process. Advancement in the gene-editing systems such as Zinc-Finger Nucleases (ZFNs), Transcription activator-like effector nucleases (TALENs), and the Clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated 9 (Cas9) system have dramatically increased the efficiency of producing GE pigs. These gene-editing systems, specifically engineered endonucleases, are based on inducing double-stranded breaks (DSBs) at a specific location, and then site-specific modifications can be introduced through one of the two DNA repair pathways: non-homologous end joining (NHEJ) or homology direct repair (HDR). Random insertions or deletions (indels) can be introduced through NHEJ and specific nucleotide sequences can be introduced through HDR, if donor DNA is provided. Use of these engineered endonucleases provides a higher success in genetic modifications, multiallelic modification of the genome, and an opportunity to introduce site-specific modifications during embryogenesis, thus bypassing the need of SCNT in GE pig production. This review will provide a historical prospective of GE pig production and examples of how the gene-editing system, led by engineered endonucleases, have improved GE pig production. We will also present some of our current progress related to the optimal use of CRISPR/Cas9 system during embryogenesis.

Sclt1 deficiency causes cystic kidney by activating ERK and STAT3 signaling

Ciliopathies form a group of inherited disorders sharing several clinical manifestations because of abnormal cilia formation or function, and few treatments have been successful against these disorders. Here, we report a mouse model with mutated Sclt1 gene, which encodes a centriole distal appendage protein important for ciliogenesis. Sodium channel and clathrin linker 1 (SCLT1) mutations were associated with the oral-facial-digital syndrome (OFD), an autosomal recessive ciliopathy. The Sclt1-/- mice exhibit typical ciliopathy phenotypes, including cystic kidney, cleft palate and polydactyly. Sclt1-loss decreases the number of cilia in kidney; increases proliferation and apoptosis of renal tubule epithelial cells; elevates protein kinase A, extracellular signal-regulated kinases, SMAD and signal transducer and activator of transcription 3 (STAT3) pathways; and enhances pro-inflammation and pro-fibrosis pathways with disease progression. Embryonic kidney cyst formation of Sclt1-/- mice was effectively reduced by an anti-STAT3 treatment using pyrimethamine. Overall, we reported a new mouse model for the OFD; and our data suggest that STAT3 inhibition may be a promising treatment for SCLT1-associated cystic kidney.

Molecular autopsy in maternal-fetal medicine

PurposeThe application of genomic sequencing to investigate unexplained death during early human development, a form of lethality likely enriched for severe Mendelian disorders, has been limited.MethodsIn this study, we employed exome sequencing as a molecular autopsy tool in a cohort of 44 families with at least one death or lethal fetal malformation at any stage of in utero development. Where no DNA was available from the fetus, we performed molecular autopsy by proxy, i.e., through parental testing.ResultsPathogenic or likely pathogenic variants were identified in 22 families (50%), and variants of unknown significance were identified in further 15 families (34%). These variants were in genes known to cause embryonic or perinatal lethality (ALPL, GUSB, SLC17A5, MRPS16, THSD1, PIEZO1, and CTSA), genes known to cause Mendelian phenotypes that do not typically include embryonic lethality (INVS, FKTN, MYBPC3, COL11A2, KRIT1, ASCC1, NEB, LZTR1, TTC21B, AGT, KLHL41, GFPT1, and WDR81) and genes with no established links to human disease that we propose as novel candidates supported by embryonic lethality of their orthologs or other lines of evidence (MS4A7, SERPINA11, FCRL4, MYBPHL, PRPF19, VPS13D, KIAA1109, MOCS3, SVOPL, FEN1, HSPB11, KIF19, and EXOC3L2).ConclusionOur results suggest that molecular autopsy in pregnancy losses is a practical and high-yield alternative to traditional autopsy, and an opportunity for bringing precision medicine to the clinical practice of perinatology.

Inversin correlates with the malignant phenotype of non-small cell lung cancer and promotes the invasiveness of lung cancer cells

Inversin, encoded by NPHP2, is one of the 10 NPHP proteins known to be involved in nephronophthisis (an autosomal recessive cystic kidney). Although the previous reports showed that inversin played an important role in embryonic development and renal diseases, its function in cancer was not revealed clearly so far. As measured by immunohistochemical staining, inversin was highly expressed in the cytoplasm of lung cancer samples (63.4%, 161/254) compared with adjacent normal lung tissues (22.0%, 11/50, p < 0.01). Moreover, its expression was positively correlated with differentiation ( p = 0.014), tumor node metastasis staging ( p = 0.007), and lymph node metastasis ( p = 0.020). The overall survival of non-small cell lung cancer patients with inversin positive expression (45.41 ± 1.800 months) was significantly reduced compared with those with inversin negative expression (51.046 ± 2.238 months, p = 0.042). Consistently, we found that the invasion capacity of A549 cells transfected with inversin was significantly stronger than that of control cells ( p < 0.05), while inversin siRNA-treatment significantly reduced cell invasion in H1299 cells ( p < 0.05). Additionally, we demonstrated that inversin could upregulate the expression of N-cadherin, Vimentin, matrix metalloproteinase-2, and matrix metalloproteinase-9. Collectively, these results indicated that inversin might promote the tumorigenicity of lung cancer cells and serve as a novel therapeutic target of non-small cell lung cancer.

Laparoscopic cholecystectomy in a case of situs inversus totalis: a review of technical challenges and adaptations

Situs inversus totalis is a rare congenital condition, characterized by the transposition of the thoracic and abdominal viscera, resulting in a mirror image of normal anatomy. Even though situs inversus does not predispose to gall stones, a laparoscopic cholecystectomy, in a case of situs inversus, can prove to be a technically challenging procedure, especially for the right-handed surgeon. In this case report, we present an unusual case of cholelithiasis in a patient with situs inversus totalis. A laparoscopic cholecystectomy, which is considered the gold standard procedure for symptomatic gallstones, was performed. The technical challenges that were anticipated due to anatomical anomalies were managed by various preoperative and intraoperative modifications. Through this present case report, we concluded that a laparoscopic cholecystectomy is a feasible and safe procedure in patients with situs inversus totalis and can be precisely performed by a right-handed surgeon, with necessary adaptations.

Tbx5 Buffers Inherent Left/Right Asymmetry Ensuring Symmetric Forelimb Formation

The forelimbs and hindlimbs of vertebrates are bilaterally symmetric. The mechanisms that ensure symmetric limb formation are unknown but they can be disrupted in disease. In Holt-Oram Syndrome (HOS), caused by mutations in TBX5, affected individuals have left-biased upper/forelimb defects. We demonstrate a role for the transcription factor Tbx5 in ensuring the symmetric formation of the left and right forelimb. In our mouse model, bilateral hypomorphic levels of Tbx5 produces asymmetric forelimb defects that are consistently more severe in the left limb than the right, phenocopying the left-biased limb defects seen in HOS patients. In Tbx hypomorphic mutants maintained on an INV mutant background, with situs inversus, the laterality of defects is reversed. Our data demonstrate an early, inherent asymmetry in the left and right limb-forming regions and that threshold levels of Tbx5 are required to overcome this asymmetry to ensure symmetric forelimb formation.

Externally, the human form appears bilaterally symmetric. For example, each of our pairs of arms and legs are the same length. This external symmetry masks many asymmetries found in internal organs. In most people the heart is found on the left side of the chest. The stomach, liver and spleen are also positioned asymmetrically. The authors of this study demonstrate, using a mouse model, that bilateral symmetry of the arms is not a default, passive state but that mechanisms are in place that ensure symmetrical formation of the left and right limbs. Bilateral symmetry of the arms is achieved by the action of a gene Tbx5 that masks the effects of signals that acted earlier during embryogenesis, many days before limb formation, and imposed asymmetries on the forming internal organs. Maintaining bilateral symmetry of the arms is important for them to carry out their normal functions but this process can go wrong. Holt-Oram syndrome patients have upper limb defects, including shortened arms. Consistently the defects are more severe in their left arm than right. This birth defect is caused by disruption of the TBX5 gene. By linking the action of Tbx5 to symmetrical limb formation, the authors provide an explanation for why Holt-Oram syndrome patients have more severe defects in the left arms than right.

Heterotaxy in Caenorhabditis: widespread natural variation in left-right arrangement of the major organs

Although the arrangement of internal organs in most metazoans is profoundly left-right (L/R) asymmetric with a predominant handedness, rare individuals show full (mirror-symmetric) or partial (heterotaxy) reversals. While the nematode Caenorhabditis elegans is known for its highly determinate development, including stereotyped L/R organ handedness, we found that L/R asymmetry of the major organs, the gut and gonad, varies among natural isolates of the species in both males and hermaphrodites. In hermaphrodites, heterotaxy can involve one or both bilaterally asymmetric gonad arms. Male heterotaxy is probably not attributable to relaxed selection in this hermaphroditic species, as it is also seen in gonochoristic Caenorhabditis species. Heterotaxy increases in many isolates at elevated temperature, with one showing a pregastrulation temperature-sensitive period, suggesting a very early embryonic or germline effect on this much later developmental outcome. A genome-wide association study of 100 isolates showed that male heterotaxy is associated with three genomic regions. Analysis of recombinant inbred lines suggests that a small number of loci are responsible for the observed variation. These findings reveal that heterotaxy is a widely varying quantitative trait in an animal with an otherwise highly stereotyped anatomy, demonstrating unexpected plasticity in an L/R arrangement of the major organs even in a simple animal.This article is part of the themed issue 'Provocative questions in left-right asymmetry'.

Lamin A/C Is Required for ChAT-Dependent Neuroblastoma Differentiation

The mouse neuroblastoma N18TG2 clone is unable to differentiate and is defective for the enzymes of the biosynthesis of neurotransmitters. The forced expression of choline acetyltransferase (ChAT) in these cells results in the synthesis and release of acetylcholine (Ach) and hence in the expression of neurospecific features and markers. To understand how the expression of ChAT triggered neuronal differentiation, we studied the differences in genome-wide transcription profiles between the N18TG2 parental cells and its ChAT-expressing 2/4 derived clone. The engagement of the 2/4 cells in the neuronal developmental program was confirmed by the increase of the expression level of several differentiation-related genes and by the reduction of the amount of transcripts of cell cycle genes. At the same time, we observed a massive reorganization of cytoskeletal proteins in terms of gene expression, with the accumulation of the nucleoskeletal lamina component Lamin A/C in differentiating cells. The increase of the Lmna transcripts induced by ChAT expression in 2/4 cells was mimicked treating the parental N18TG2 cells with the acetylcholine receptor agonist carbachol, thus demonstrating the direct role played by this receptor in neuron nuclei maturation. Conversely, a treatment of 2/4 cells with the muscarinic receptor antagonist atropine resulted in the reduction of the amount of Lmna RNA. Finally, the hypothesis that Lmna gene product might play a crucial role in the ChAT-dependent molecular differentiation cascade was strongly supported by Lmna knockdown in 2/4 cells leading to the downregulation of genes involved in differentiation and cytoskeleton formation and to the upregulation of genes known to regulate self-renewal and stemness.

Anaesthetic Management for Appendectomy in a Patient with Situs Inversus Totalis

Situs inversus totalis is a congenital syndrome, in which all the internal organs are in the opposite position, including dextrokardia. Most patients are asymptomatic and maintain their normal life. Kartagener syndrome may accompany situs inversus totalis. Diagnosis may be overlooked in patients with situs inversus totalis in emergency situations. Patients with this syndrome should inform the clinician as this will facilitate the diagnosis. Acute appendicitis is an emergency situation that would require urgent intervention. Appendicitis symptoms can be observed in the left lower quadrant of patients. We present a case concerning the anaesthetic management of a patient with situs inversus undergoing an emergency appendectomy.

Structural basis of the Inv compartment and ciliary abnormalities in Inv/nphp2 mutant mice

The primary cilium is a hair like structure protruding from most mammalian cells. The basic design of the primary cilium consists of a nine microtubule doublet structure (the axoneme). The Inv compartment, a distinct proximal segment of the ciliary body, is defined as the region in which the Inv protein is localized. Inv gene is a responsible gene for human nephronophthisis type2 (NPHP2). Here, we show that renal cilia have a short proximal microtubule doublet region and a long distal microtubule singlet region. The length of the Inv compartment was similar to that of the microtubule doublet region, suggesting a possibility that the doublet region is the structural basis of the Inv compartment. Respiratory cilia of inv mouse mutants had ciliary rootlet malformation and showed reduced ciliary beating frequency and ciliary beating angle, which may explain recurrent bronchitis in NPHP2 patients. In multiciliated tracheal cells, most Inv proteins were retained in the basal body and did not accumulate in the Inv compartment. These results suggest that the machinery to transport and retain Inv in cilia is different between renal and tracheal cilia and that Inv may function in the basal body of tracheal cells.

[Removal of Choledocholith by Endoscopic Retrograde Cholangiopancreatography in a Situs Invsersus Patient]

Situs inversus is an extremely rare autosomal recessive disease with left-right inversion of internal organs. It carries technical difficulties in diagnostic or therapeutic procedures. There have been a few case reports on stone extraction by ERCP in situs inversus patients. ERCP techniques in situs inversus can be classified into conventional method and mirror image method. In mirror image method, the procedure is performed with the patient in the right lateral decubitus position and the endoscopist on the patient's left side. Until now, there is no consensus about which method is better. Herein, we report an unusual case of choledocholithiasis in a patient with situs inversus who underwent ERCP for stone extraction by both conventional method and mirror image method.

Cellular and Nuclear Alignment Analysis for Determining Epithelial Cell Chirality

Left-right (LR) asymmetry is a biologically conserved property in living organisms that can be observed in the asymmetrical arrangement of organs and tissues and in tissue morphogenesis, such as the directional looping of the gastrointestinal tract and heart. The expression of LR asymmetry in embryonic tissues can be appreciated in biased cell alignment. Previously an in vitro chirality assay was reported by patterning multiple cells on microscale defined geometries and quantified the cell phenotype-dependent LR asymmetry, or cell chirality. However, morphology and chirality of individual cells on micropatterned surfaces has not been well characterized. Here, a Python-based algorithm was developed to identify and quantify immunofluorescence stained individual epithelial cells on multicellular patterns. This approach not only produces results similar to the image intensity gradient-based method reported previously, but also can capture properties of single cells such as area and aspect ratio. We also found that cell nuclei exhibited biased alignment. Around 35% cells were misaligned and were typically smaller and less elongated. This new imaging analysis approach is an effective tool for measuring single cell chirality inside multicellular structures and can potentially help unveil biophysical mechanisms underlying cellular chiral bias both in vitro and in vivo.

Leriche syndrome in a patient with situs inversus totalis

Situs inversus is a rare congenital defect defined by a mirror image anatomic variation of the thoracic and abdominal organs. In this situation, abdominal aortic surgery may become particularly challenging. This is the case of a 51-year-old man, who presented with an incapacitating lower limb claudication. On his workup, a complete occlusion of the infrarenal aorta requiring surgical revascularization was found. Additionally, a situs inversus totalis was identified along with a single horseshoe kidney. The patient underwent uneventfully a surgical aortobifemoral interposition. The sole modification to the standard procedure regarded the graft limbs tunneling, which was performed in a prerenal pathway in the retroperitoneal space, thus avoiding iatrogenic injury to the anteriorly positioned iliac veins. Although challenging, conventional aortic surgery can be safely accomplished in patients with situs inversus totalis.

Pathogenesis of biliary atresia: defining biology to understand clinical phenotypes

Biliary atresia is a severe cholangiopathy of early infancy that destroys extrahepatic bile ducts and disrupts bile flow. With a poorly defined disease pathogenesis, treatment consists of the surgical removal of duct remnants followed by hepatoportoenterostomy. Although this approach can improve the short-term outcome, the liver disease progresses to end-stage cirrhosis in most children. Further improvement in outcome will require a greater understanding of the mechanisms of biliary injury and fibrosis. Here, we review progress in the field, which has been fuelled by collaborative studies in larger patient cohorts and the development of cell culture and animal model systems to directly test hypotheses. Advances include the identification of phenotypic subgroups and stages of disease based on clinical, pathological and molecular features. Stronger evidence exists for viruses, toxins and gene sequence variations in the aetiology of biliary atresia, triggering a proinflammatory response that injures the duct epithelium and produces a rapidly progressive cholangiopathy. The immune response also activates the expression of type 2 cytokines that promote epithelial cell proliferation and extracellular matrix production by nonparenchymal cells. These advances provide insight into phenotype variability and might be relevant to the design of personalized trials to block progression of liver disease.

ANKS6 is the critical activator of NEK8 kinase in embryonic situs determination and organ patterning

The ciliary kinase NEK8 plays a critical role in situs determination and cystic kidney disease, yet its exact function remains unknown. In this study, we identify ANKS6 as a target and activator of NEK8. ANKS6 requires NEK8 for localizing to the ciliary inversin compartment (IC) and activates NEK8 by binding to its kinase domain. Here we demonstrate the functional importance of this interaction through the analysis of two novel mouse mutations, Anks6(Streaker) and Nek8(Roc). Both display heterotaxy, cardiopulmonary malformations and cystic kidneys, a syndrome also characteristic of mutations in Invs and Nphp3, the other known components of the IC. The Anks6(Strkr) mutation decreases ANKS6 interaction with NEK8, precluding NEK8 activation. The Nek8(Roc) mutation inactivates NEK8 kinase function while preserving ANKS6 localization to the IC. Together, these data reveal the crucial role of NEK8 kinase activation within the IC, promoting proper left-right patterning, cardiopulmonary development and renal morphogenesis.

Situs inversus and ciliary abnormalities: 20 years later, what is the connection?

Heterotaxy (also known as situs ambiguous) and situs inversus totalis describe disorders of laterality in which internal organs do not display their typical pattern of asymmetry. First described around 1600 by Girolamo Fabrizio, numerous case reports about laterality disorders in humans were published without any idea about the underlying cause. Then, in 1976, immotile cilia were described as the cause of a human syndrome that was previously clinically described, both in 1904 by AK Siewert and in 1933 by Manes Kartagener, as an association of situs inversus with chronic sinusitis and bronchiectasis, now commonly known as Kartagener’s syndrome. Despite intense research, the underlying defect of laterality disorders remained unclear. Nearly 20 years later in 1995, Björn Afzelius discussed five hypotheses to explain the connection between ciliary defects and loss of laterality control in a paper published in the International Journal of Developmental Biology asking: ‘Situs inversus and ciliary abnormalities: What is the connection?’. Here, nearly 20 research years later, we revisit some of the key findings that led to the current knowledge about the connection between situs inversus and ciliary abnormalities.

Diversity and convergence in the mechanisms establishing L/R asymmetry in metazoa

Differentiating left and right hand sides during embryogenesis represents a major event in body patterning. Left-Right (L/R) asymmetry in bilateria is essential for handed positioning, morphogenesis and ultimately the function of organs (including the brain), with defective L/R asymmetry leading to severe pathologies in human. How and when symmetry is initially broken during embryogenesis remains debated and is a major focus in the field. Work done over the past 20 years, in both vertebrate and invertebrate models, has revealed a number of distinct pathways and mechanisms important for establishing L/R asymmetry and for spreading it to tissues and organs. In this review, we summarize our current knowledge and discuss the diversity of L/R patterning from cells to organs during evolution.

Translational research in ADPKD: lessons from animal models

Autosomal dominant polycystic kidney disease (ADPKD) is caused by mutations in PKD1 or PKD2, which encode polycystin-1 and polycystin-2, respectively. Rodent models are available to study the pathogenesis of polycystic kidney disease (PKD) and for preclinical testing of potential therapies-either genetically engineered models carrying mutations in Pkd1 or Pkd2 or models of renal cystic disease that do not have mutations in these genes. The models are characterized by age at onset of disease, rate of disease progression, the affected nephron segment, the number of affected nephrons, synchronized or unsynchronized cyst formation and the extent of fibrosis and inflammation. Mouse models have provided valuable mechanistic insights into the pathogenesis of PKD; for example, mutated Pkd1 or Pkd2 cause renal cysts but additional factors are also required, and the rate of cyst formation is increased in the presence of renal injury. Animal studies have also revealed complex genetic and functional interactions among various genes and proteins associated with PKD. Here, we provide an update on the preclinical models commonly used to study the molecular pathogenesis of ADPKD and test potential therapeutic strategies. Progress made in understanding the pathophysiology of human ADPKD through these animal models is also discussed.

Ciliopathies: the trafficking connection

The primary cilium (PC) is a very dynamic hair-like membrane structure that assembles/disassembles in a cell-cycle-dependent manner and is present in almost every cell type. Despite being continuous with the plasma membrane, a diffusion barrier located at the ciliary base confers the PC properties of a separate organelle with very specific characteristics and membrane composition. Therefore, vesicle trafficking is the major process by which components are acquired for cilium formation and maintenance. In fact, a system of specific sorting signals controls the right of cargo admission into the cilia. Disruption to the ciliary structure or its function leads to multiorgan diseases known as ciliopathies. These illnesses arise from a spectrum of mutations in any of the more than 50 loci linked to these conditions. Therefore, it is not surprising that symptom variability (specific manifestations and severity) among and within ciliopathies appears to be an emerging characteristic. Nevertheless, one can speculate that mutations occurring in genes whose products contribute to the overall vesicle trafficking to the PC (i.e. affecting cilia assembly) will lead to more severe symptoms, whereas those involved in the transport of specific cargoes will result in milder phenotypes. In this review, we summarize the trafficking mechanisms to the cilia and also provide a description of the trafficking defects observed in some ciliopathies which can be correlated to the severity of the pathology.

Cilia and polycystic kidney disease, kith and kin

In the past decade, cilia have been found to play important roles in renal cystogenesis. Many genes, such as PKD1 and PKD2 which, when mutated, cause autosomal dominant polycystic kidney disease (ADPKD), have been found to localize to primary cilia. The cilium functions as a sensor to transmit extracellular signals into the cell. Abnormal cilia structure and function are associated with the development of polyscystic kidney disease (PKD). Cilia assembly includes centriole migration to the apical surface of the cell, ciliary vesicle docking and fusion with the cell membrane at the intended site of cilium outgrowth, and microtubule growth from the basal body. This review summarizes the most recent advances in cilia and PKD research, with special emphasis on the mechanisms of cytoplasmic and intraciliary protein transport during ciliogenesis.

Cardiac looping may be driven by compressive loads resulting from unequal growth of the heart and pericardial cavity. Observations on a physical simulation model

The transformation of the straight embryonic heart tube into a helically wound loop is named cardiac looping. Such looping is regarded as an essential process in cardiac morphogenesis since it brings the building blocks of the developing heart into an approximation of their definitive topographical relationships. During the past two decades, a large number of genes have been identified which play important roles in cardiac looping. However, how genetic information is physically translated into the dynamic form changes of the looping heart is still poorly understood. The oldest hypothesis of cardiac looping mechanics attributes the form changes of the heart loop (ventral bending → simple helical coiling → complex helical coiling) to compressive loads resulting from growth differences between the heart and the pericardial cavity. In the present study, we have tested the physical plausibility of this hypothesis, which we call the growth-induced buckling hypothesis, for the first time. Using a physical simulation model, we show that growth-induced buckling of a straight elastic rod within the confined space of a hemispherical cavity can generate the same sequence of form changes as observed in the looping embryonic heart. Our simulation experiments have furthermore shown that, under bilaterally symmetric conditions, growth-induced buckling generates left- and right-handed helices (D-/L-loops) in a 1:1 ratio, while even subtle left- or rightward displacements of the caudal end of the elastic rod at the pre-buckling state are sufficient to direct the buckling process toward the generation of only D- or L-loops, respectively. Our data are discussed with respect to observations made in biological “models.” We conclude that compressive loads resulting from unequal growth of the heart and pericardial cavity play important roles in cardiac looping. Asymmetric positioning of the venous heart pole may direct these forces toward a biased generation of D- or L-loops.

Orthotopic liver transplantation in situs inversus adult from an ABO-incompatible donor with situs inversus

Background

Situs inversus is a rare congenital anomaly characterized by the complete inversion of thoracic and abdominal organs. Liver transplantation in such patients or from donors in situs inversus is technically challenging because of the reversed anatomic structures. A small number of successful liver transplantation cases concerning situs inverus in either recipients or donors have been recently reported with different graft position and orientation. Here we reported an extremely rare case of liver retransplantation from an ABO incompatible situs inversus donor to an adult situs inversus recipient.

Case presentation

A 53-year-old complete situs inversus man developed graft failure due to severe biliary complication after his first liver transplantation from a situs solitus donor. Re-transplantation was performed using a graft liver from a likewise situs inversus donor. Although the blood type between donor and recipient was incompatible, the post-operative outcome was excellent under proper prophylaxis to the antibody-mediated rejection.

Conclusion

To the best of our knowledge, this is the first report of liver transplantation from situs inversus to situs inversus in adult recipient. Liver transplantation using situs matching donor makes the procedure much easier at the surgical point of view, which has a benefit of less potential surgical complications. Furthermore, ABO-incompatibility is acceptable for donor allocation in cases that both donor and recipient are situs inversus.

Multiple renal cyst development but not situs abnormalities in transgenic RNAi mice against Inv::GFP rescue gene

In this study we generated RNA interference (RNAi)-mediated gene knockdown transgenic mice (transgenic RNAi mice) against the functional Inv gene. Inv mutant mice show consistently reversed internal organs (situs inversus), multiple renal cysts and neonatal lethality. The Inv::GFP-rescue mice, which introduced the Inv::GFP fusion gene, can rescue inv mutant mice phenotypes. This indicates that the Inv::GFP gene is functional in vivo. To analyze the physiological functions of the Inv gene, and to demonstrate the availability of transgenic RNAi mice, we introduced a short hairpin RNA expression vector against GFP mRNA into Inv::GFP-rescue mice and analyzed the gene silencing effects and Inv functions by examining phenotypes. Transgenic RNAi mice with the Inv::GFP-rescue gene (Inv-KD mice) down-regulated Inv::GFP fusion protein and showed hypomorphic phenotypes of inv mutant mice, such as renal cyst development, but not situs abnormalities or postnatal lethality. This indicates that shRNAi-mediated gene silencing systems that target the tag sequence of the fusion gene work properly in vivo, and suggests that a relatively high level of Inv protein is required for kidney development in contrast to left/right axis determination. Inv::GFP protein was significantly down-regulated in the germ cells of Inv-KD mice testis compared with somatic cells, suggesting the existence of a testicular germ cell-specific enhanced RNAi system that regulates germ cell development. The Inv-KD mouse is useful for studying Inv gene functions in adult tissue that are unable to be analyzed in inv mutant mice showing postnatal lethality. In addition, the shRNA-based gene silencing system against the tag sequence of the fusion gene can be utilized as a new technique to regulate gene expression in either in vitro or in vivo experiments.

Situs inversus with dextrocardia in a mummy case

A mummy of a young woman, who died due to tuberculous peritonitis and salpingitis, is conserved in the Pathological Anatomy Museum of the University of Padua. It was found at autopsy to have situs inversus of viscera with dextrocardia, apparently in the absence of other congenital defects. A 64-section scanner computed tomography (CT) on the specimen was carried out to investigate the internal condition of organs. The CT revealed the presence in the heart of a muscular ventricular septal defect and of calcific deposits on visceral pericardium and aortic wall, in keeping with sequelae of previous tuberculous pericarditis.

Aetiology of biliary atresia: what is actually known?

Biliary atresia (BA) is a rare disease of unknown etiology and unpredictable outcome, even when there has been timely diagnosis and exemplary surgery. It has been the commonest indication for liver transplantation during childhood for the past 20 years. Hence much clinical and basic research has been directed at elucidating the origin and pathology of BA. This review summarizes the current clinical variations of BA in humans, its occasional appearance in animals and its various manifestations in the laboratory as an experimental model.

Mouse models of polycystic kidney disease induced by defects of ciliary proteins

Polycystic kidney disease (PKD) is a common hereditary disorder which is characterized by fluid-filled cysts in the kidney. Mutation in either PKD1, encoding polycystin-1 (PC1), or PKD2, encoding polycystin-2 (PC2), are causative genes of PKD. Recent studies indicate that renal cilia, known as mechanosensors, detecting flow stimulation through renal tubules, have a critical function in maintaining homeostasis of renal epithelial cells. Because most proteins related to PKD are localized to renal cilia or have a function in ciliogenesis. PC1/PC2 heterodimer is localized to the cilia, playing a role in calcium channels. Also, disruptions of ciliary proteins, except for PC1 and PC2, could be involved in the induction of polycystic kidney disease. Based on these findings, various PKD mice models were produced to understand the roles of primary cilia defects in renal cyst formation. In this review, we will describe the general role of cilia in renal epithelial cells, and the relationship between ciliary defects and PKD. We also discuss mouse models of PKD related to ciliary defects based on recent studies. [BMB Reports 2013; 46(2): 73-79]