Wnt7b is a signaling protein that plays a crucial role for many developmental processes including placental, lung, eye, dendrite, and bone formation along with kidney development. The primary role of Wnt7b is to establish the cortico-medullary axis of epithelial organization.
Protein Wnt-7b is a protein that in humans is encoded by the WNT7B gene. [5] [6] [7] [8]
The WNT gene family consists of structurally related genes that encode secreted signaling proteins. These proteins have been implicated in oncogenesis and in several developmental processes, including regulation of cell fate and patterning during embryogenesis. This gene is a member of the WNT gene family. It encodes a protein showing 99% and 91% amino acid identity to the mouse and Xenopus Wnt7A proteins, respectively. Among members of the human WNT family, this protein is most similar to WNT7A protein (77.1% total amino acid identity). This gene may play important roles in the development and progression of gastric cancer, esophageal cancer, and pancreatic cancer. [8]
Wnt7b is a key paracrine signaling factor secreted by the ureteric epithelium that establishes the cortico-medullary axis of the mammalian kidney. [9] Wnt7b is a signaling protein that plays a crucial role for many developmental processes including placental, lung, eye, dendrite, and bone formation along with kidney development. The primary role of Wnt7b is to establish the cortico-medullary axis of epithelial organization. The establishment of the cortico-medullary axis plays an essential role for the development of the medullary component of the kidney. Wnt7b regulates orientation of cell divisions in renal medullary collecting duct epithelium, in which is the major structure driving renal medulla formation. There are two interstitial regulators that are explicitly linked to medullary development; Pod1 which encodes a transcription factor expressed in the renal interstitium while p57Kip2 encodes a cyclin-dependent kinase inhibitor which is linked to Beckwith-Wiedemann syndrome. Pod1, p57Kip2 and integrin α3 (ITGA3) are three factors that are involved in renal medullary morphogenesis. The knockout of Pod1 results in no renal medullary formation while p57Kip2 and Itga3 knockouts resulted in a reduced renal medulla. Removal of Wnt7b activity leads to a failure of medullary development while other aspects of kidney development including ureteric branching, development of the renal cortex, and nephrogenesis are unaffected. The absence of renal medulla also affects the plane of epithelial cell division along with little proliferative growth of the loop of Henle. Wnt7b null allele will result in fatality due to the diminution of placental function leading to the failure to initiate organogenesis. [9]
The nephronthe minute or microscopic structural and functional unit of the kidney. It is composed of a renal corpuscle and a renal tubule. The renal corpuscle consists of a tuft of capillaries called a glomerulus and a cup-shaped structure called Bowman's capsule. The renal tubule extends from the capsule. The capsule and tubule are connected and are composed of epithelial cells with a lumen. A healthy adult has 1 to 1.5 million nephrons in each kidney. Blood is filtered as it passes through three layers: the endothelial cells of the capillary wall, its basement membrane, and between the foot processes of the podocytes of the lining of the capsule. The tubule has adjacent peritubular capillaries that run between the descending and ascending portions of the tubule. As the fluid from the capsule flows down into the tubule, it is processed by the epithelial cells lining the tubule: water is reabsorbed and substances are exchanged ; first with the interstitial fluid outside the tubules, and then into the plasma in the adjacent peritubular capillaries through the endothelial cells lining that capillary. This process regulates the volume of body fluid as well as levels of many body substances. At the end of the tubule, the remaining fluid—urine—exits: it is composed of water, metabolic waste, and toxins.
The collecting duct system of the kidney consists of a series of tubules and ducts that physically connect nephrons to a minor calyx or directly to the renal pelvis. The collecting duct system is the last part of nephron and participates in electrolyte and fluid balance through reabsorption and excretion, processes regulated by the hormones aldosterone and vasopressin.
Intermediate mesoderm or intermediate mesenchyme is a narrow section of the mesoderm located between the paraxial mesoderm and the lateral plate of the developing embryo. The intermediate mesoderm develops into vital parts of the urogenital system, as well as the reproductive system.
WNT4 is a secreted protein that in humans is encoded by the Wnt4 gene, found on chromosome 1. It promotes female sex development and represses male sex development. Loss of function can have serious consequences, such as female to male sex reversal.
Paired box gene 2, also known as Pax-2, is a protein which in humans is encoded by the PAX2 gene.
Protein Wnt-5a is a protein that in humans is encoded by the WNT5A gene.
Protein Wnt-3a is a protein that in humans is encoded by the WNT3A gene.
Protein Wnt-7a is a protein that in humans is encoded by the WNT7A gene.
Inversin is a protein that in humans is encoded by the INVS gene.
Cadherin-16 is a protein that in humans is encoded by the CDH16 gene.
Proto-oncogene protein Wnt-3 is a protein that in humans is encoded by the WNT3 gene.
Protein odd-skipped-related 1 is a transcription factor that in humans is encoded by the OSR1 gene. The OSR1 and OSR2 transcription factors participate in the normal development of body parts such as the kidney.
Protein Wnt-10b is a protein that in humans is encoded by the WNT10B gene.
Protein Wnt-11 is a protein that in humans is encoded by the WNT11 gene.
Protein Wnt-2b is a protein that in humans is encoded by the WNT2B gene.
Protein Wnt-9a is a protein that in humans is encoded by the WNT9A gene.
Protein Wnt-16 is a protein that in humans is encoded by the WNT16 gene. It has been proposed that stimulation of WNT16 expression in nearby normal cells is responsible for the development of chemotherapy-resistance in cancer cells.
Protein Wnt-5b is a protein that in humans is encoded by the WNT5B gene.
Protein Wnt-8b is a protein that in humans is encoded by the WNT8B gene.
Protein Wnt-9b is a protein that in humans is encoded by the WNT9B gene.