SLC26A7 protein is a chloride/bicarbonate exchanger and its abundance is osmolarity- and pH-dependent in renal epithelial cells

A first complete catalog of highly expressed genes in eight chicken tissues reveals uncharacterized gene families specific for the chicken testis

Based on next-generation sequencing, we established a repertoire of differentially overexpressed genes (DoEGs) in eight adult chicken tissues: the testis, brain, lung, liver, kidney, muscle, heart, and intestine. With 4,499 DoEGs, the testis had the highest number and proportion of DoEGs compared with the seven somatic tissues. The testis DoEG set included the highest proportion of long noncoding RNAs (lncRNAs; 1,851, representing 32% of the lncRNA genes in the whole genome) and the highest proportion of protein-coding genes (2,648, representing 14.7% of the protein-coding genes in the whole genome). The main significantly enriched Gene Ontology terms related to the protein-coding genes were "reproductive process," "tubulin binding," and "microtubule cytoskeleton." Using real-time quantitative reverse transcription-polymerase chain reaction, we confirmed the overexpression of genes that encode proteins already described in chicken sperm [such as calcium binding tyrosine phosphorylation regulated (CABYR), spermatogenesis associated 18 (SPATA18), and CDK5 regulatory subunit associated protein (CDK5RAP2)] but whose testis origin had not been previously confirmed. Moreover, we demonstrated the overexpression of vertebrate orthologs of testis genes not yet described in the adult chicken testis [such as NIMA related kinase 2 (NEK2), adenylate kinase 7 (AK7), and CCNE2]. Using clustering according to primary sequence homology, we found that 1,737 of the 2,648 (67%) testis protein-coding genes were unique genes. This proportion was significantly higher than the somatic tissues except muscle. We clustered the other 911 testis protein-coding genes into 495 families, from which 47 had all paralogs overexpressed in the testis. Among these 47 testis-specific families, eight contained uncharacterized duplicated paralogs without orthologs in other metazoans except birds: these families are thus specific for chickens/birds.NEW & NOTEWORTHY Comparative next-generation sequencing analysis of eight chicken tissues showed that the testis has highest proportion of long noncoding RNA and protein-coding genes of the whole genome. We identified new genes in the chicken testis, including orthologs of known mammalian testicular genes. We also identified 47 gene families in which all the members were overexpressed, if not exclusive, in the testis. Eight families, organized in duplication clusters, were unknown, without orthologs in metazoans except birds, and are thus specific for chickens/birds.

Chloride/Multiple Anion Exchanger SLC26A Family: Systemic Roles of SLC26A4 in Various Organs

Solute carrier family 26 member 4 (SLC26A4) is a member of the SLC26A transporter family and is expressed in various tissues, including the airway epithelium, kidney, thyroid, and tumors. It transports various ions, including bicarbonate, chloride, iodine, and oxalate. As a multiple-ion transporter, SLC26A4 is involved in the maintenance of hearing function, renal function, blood pressure, and hormone and pH regulation. In this review, we have summarized the various functions of SLC26A4 in multiple tissues and organs. Moreover, the relationships between SLC26A4 and other channels, such as cystic fibrosis transmembrane conductance regulator, epithelial sodium channel, and sodium chloride cotransporter, are highlighted. Although the modulation of SLC26A4 is critical for recovery from malfunctions of various organs, development of specific inducers or agonists of SLC26A4 remains challenging. This review contributes to providing a better understanding of the role of SLC26A4 and development of therapeutic approaches for the SLC26A4-associated hearing loss and SLC26A4-related dysfunction of various organs.

State of knowledge on ammonia handling by the kidney

The disposal of ammonia, the main proton buffer in the urine, is important for acid-base homeostasis. Renal ammonia excretion is the predominant contributor to renal net acid excretion, both under basal condition and in response to acidosis. New insights into the mechanisms of renal ammonia production and transport have been gained in the past decades. Ammonia is the only urinary solute known to be produced in the kidney and selectively transported through the different parts of the nephron. Both molecular forms of total ammonia, NH3 and NH4+, are transported by specific proteins. Proximal tubular ammoniagenesis and the activity of these transport processes determine the eventual fate of total ammonia produced and excreted by the kidney. In this review, we summarized the state of the art of ammonia handling by the kidney and highlighted the newest processes described in the last decade.

Structure and function of proteins in membranes and nanodiscs

The field of membrane structural biology represents a fast-moving field with exciting developments including native nanodiscs that allow preparation of complexes of post-translationally modified proteins bound to biological lipids. This has led to conceptual advances including biological membrane:protein assemblies or “memteins” as the fundamental functional units of biological membranes. Tools including cryo-electron microscopy and X-ray crystallography are maturing such that it is becoming increasingly feasible to solve structures of large, multicomponent complexes, while complementary methods including nuclear magnetic resonance spectroscopy yield unique insights into interactions and dynamics. Challenges remain, including elucidating exactly how lipids and ligands are recognized at atomic resolution and transduce signals across asymmetric bilayers. In this special volume some of the latest thinking and methods are gathered through the analysis of a range of transmembrane targets. Ongoing work on areas including polymer design, protein labelling and microfluidic technologies will ensure continued progress on improving resolution and throughput, providing deeper understanding of this most important group of targets.