RECK modulates Notch signaling during cortical neurogenesis by regulating ADAM10 activity.

We report that during cortical development in the mouse embryo, reversion-inducing cysteine-rich protein with Kazal motifs (RECK) critically regulates Notch signaling by antagonizing the ectodomain shedding of Notch ligands, which is mediated by a disintegrin and metalloproteinase domain 10 (ADAM10). In the embryonic brain, RECK is specifically expressed in Nestin-positive neural precursor cells (NPCs). Reck-deficient NPCs undergo precocious differentiation that is associated with downregulated Nestin expression, impaired Notch signaling and defective self-renewal. These phenotypes were substantially rescued either by enhancing Notch signaling or by suppressing endogenous ADAM10 activity. Consequently, we found that RECK regulates the ectodomain shedding of Notch ligands by directly inhibiting the proteolytic activity of ADAM10. This mechanism appeared to be essential for Notch ligands to properly induce Notch signaling in neighboring cells. These findings indicate that RECK is a physiological inhibitor of ADAM10, an upstream regulator of Notch signaling and a critical modulator of brain development.

Involvement of the Reck tumor suppressor protein in maternal and embryonic vascular remodeling in mice.

BACKGROUND: Developmental angiogenesis proceeds through multiple morphogenetic events including sprouting, intussusception, and pruning. Mice lacking the membrane-anchored metalloproteinase regulator Reck die in utero around embryonic day 10.5 with halted vascular development; however, the mechanisms by which this phenotype arises remain unclear. RESULTS: We found that Reck is abundantly expressed in the cells associated with blood vessels undergoing angiogenesis or remodelling in the uteri of pregnant female mice. Some of the Reck-positive vessels show morphological features consistent with non-sprouting angiogenesis. Treatment with a vector expressing a small hairpin RNA against Reck severely disrupts the formation of blood vessels with a compact, round lumen. Similar defects were found in the vasculature of Reck-deficient or Reck conditional knockout embryos. CONCLUSIONS: Our findings implicate Reck in vascular remodeling, possibly through non-sprouting angiogenesis, in both maternal and embyonic tissues.

The Reck tumor suppressor protein alleviates tissue damage and promotes functional recovery after transient cerebral ischemia in mice.

The extracellular matrix (ECM) is important for both structural integrity and functions of the brain. Matrix metalloproteinases (MMPs) play major roles in ECM-remodeling under both physiological and pathological conditions. Reversion-inducing cysteine-rich protein with Kazal motifs (Reck) is a membrane-anchored MMP-regulator implicated in coordinated regulation of pericellular proteolysis. Although patho-physiological importance of MMPs and another group of MMP-regulators, tissue inhibitor of metalloproteinases, in brain ischemia has been demonstrated, little is known about the role of Reck in this process. In this study, we found that Reck is up-regulated in hippocampus and penumbra of subventricular zone after transient cerebral ischemia in mice. Most of the Reck-positive cells found at day 2 after ischemia are positive for Nestin as well as Ki67 and localized to the CA2 region of the hippocampus. At day 7 after ischemia, the Reck-positive cells increased in number, extended processes, expressed the reactive astrocyte marker GFAP and the neuronal marker NF200, and were widely distributed in the hippocampus. In the mutant mice carrying single functional Reck allele (Reck+/-), tissue damage and cell death after cerebral ischemia were augmented, the recovery of long-term potentiation in the hippocampus was compromised, NR2C subunit of NMDA receptor was up-regulated, gelatinolytic activity of MMPs were up-regulated and laminin-immunoreactivity was reduced. Our data implicate Reck in protection of ECM/tissue integrity and promotion of functional recovery in the brain after transient cerebral ischemia.

Localization of the membrane-anchored MMP-regulator RECK at the neuromuscular junctions.

Nerve apposition on nicotinic acetylcholine receptor clusters and invagination of the post-synaptic membrane (i.e. secondary fold formation) occur by embryonic day 18.5 at the neuromuscular junctions (NMJs) in mouse skeletal muscles. Finding the molecules expressed at the NMJ at this stage of development may help elucidating how the strong linkage between a nerve terminal and a muscle fiber is established. Immunohistochemical analyses indicated that the membrane-anchored matrix metalloproteinase regulator RECK was enriched at the NMJ in adult skeletal muscles. Confocal and electron microscopy revealed the localization of RECK immunoreactivity in secondary folds and subsynaptic intracellular compartments in muscles. Time course studies indicated that RECK immunoreactivity becomes associated with the NMJ in the diaphragm at around embryonic day 18.5 and thereafter. These findings, together with known properties of RECK, support the hypothesis that RECK participates in NMJ formation and/or maintenance, possibly by protecting extracellular components, such as synaptic basal laminae, from proteolytic degradation.

Urinary Biomarkers KIM-1 and NGAL for Detection of Chronic Kidney Disease of Uncertain Etiology (CKDu) among Agricultural Communities in Sri Lanka.

Chronic Kidney Disease of uncertain etiology (CKDu) is an emerging epidemic among farming communities in rural Sri Lanka. Victims do not exhibit common causative factors, however, histopathological studies revealed that CKDu is a tubulointerstitial disease. Urine albumin or albumin-creatinine ratio is still being used as a traditional diagnostic tool to identify CKDu, but accuracy and prevalence data generated are questionable. Urinary biomarkers have been used in similar nephropathy and are widely recognised for their sensitivity, specificity and accuracy in determining CKDu and early renal injury. However, these biomarkers have never been used in diagnosing CKDu in Sri Lanka. Male farmers (n = 1734) were recruited from 4 regions in Sri Lanka i.e. Matara and Nuwara Eliya (farming locations with no CKDu prevalence) and two CKDu emerging locations from Hambantota District in Southern Sri Lanka; Angunakolapelessa (EL1) and Bandagiriya (EL2). Albuminuria (ACR ≥ 30mg/g); serum creatinine based estimation of glomerular filtration rate (eGFR); creatinine normalized urinary kidney injury molecule (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) were measured. Fourteen new CKDu cases (18%) from EL1 and nine CKDu cases (9%) from EL2 were recognized for the first time from EL1, EL2 locations, which were previously considered as non-endemic of the disease and associated with persistent albuminuria (ACR ≥ 30mg/g Cr). No CKDu cases were identified in non-endemic study locations in Matara (CM) and Nuwara Eliya (CN). Analysis of urinary biomarkers showed urinary KIM-1 and NGAL were significantly higher in new CKDu cases in EL1 and EL2. However, we also reported significantly higher KIM-1 and NGAL in apparently healthy farmers in EL 1 and EL 2 with comparison to both control groups. These observations may indicate possible early renal damage in absence of persistent albuminuria and potential capabilities of urinary KIM-1 and NGAL in early detection of renal injury among farming communities in Southern Sri Lanka.

Arsenic and human health effects: A review.

Arsenic (As) is ubiquitous in nature and humans being exposed to arsenic via atmospheric air, ground water and food sources are certain. Major sources of arsenic contamination could be either through geological or via anthropogenic activities. In physiological individuals, organ system is described as group of organs that transact collectively and associate with other systems for conventional body functions. Arsenic has been associated with persuading a variety of complications in body organ systems: integumentary, nervous, respiratory, cardiovascular, hematopoietic, immune, endocrine, hepatic, renal, reproductive system and development. In this review, we outline the effects of arsenic on the human body with a main focus on assorted organ systems with respective disease conditions. Additionally, underlying mechanisms of disease development in each organ system due to arsenic have also been explored. Strikingly, arsenic has been able to induce epigenetic changes (in utero) and genetic mutations (a leading cause of cancer) in the body. Occurrence of various arsenic induced health effects involving emerging areas such as epigenetics and cancer along with their respective mechanisms are also briefly discussed.