ABSTRACT
The focus of the review is on roles of autophagy and pancreatic secretory trypsin inhibitor (PSTI), an endogenous trypsin inhibitor, in trypsinogen activation in acute pancreatitis. Acute pancreatitis is a disease in which tissues in and around the pancreas are autodigested by pancreatic digestive enzymes. This reaction is triggered by the intrapancreatic activation of trypsinogen. Autophagy causes trypsinogen and cathepsin B, a trypsinogen activator, to colocalize within the autolysosomes. Consequently, if the resultant trypsin activity exceeds the inhibitory activity of PSTI, the pancreatic digestive enzymes are activated, and they cause autodigestion of the acinar cells. Thus, autophagy and PSTI play important roles in the development and suppression of acute pancreatitis, respectively.
Subject(s)
Autophagy/physiology , Pancreatitis/metabolism , Trypsin Inhibitor, Kazal Pancreatic/physiology , Trypsinogen/metabolism , Acinar Cells/pathology , Animals , Cathepsin B/metabolism , Disease Models, Animal , Endoplasmic Reticulum Stress , Enzyme Activation , Glycoproteins/deficiency , Humans , Lysosomes/enzymology , Mice , Mice, Knockout , Molecular Chaperones/physiology , Pancreatitis/enzymology , Pancreatitis/pathology , Prostatic Secretory Proteins , Protein Folding , Proteolysis , Secretory Vesicles/enzymology , Transcription Factor CHOP/deficiency , Trypsin Inhibitor, Kazal Pancreatic/deficiencyABSTRACT
Abnormal development of the ocular anterior segment may lead to a spectrum of clinical phenotypes ranging from primary congenital glaucoma (PCG) to variable anterior segment dysgenesis (ASD). The main objective of this study was to identify the genetic alterations underlying recessive congenital glaucoma with ASD (CG-ASD). Next-generation DNA sequencing identified rare biallelic CPAMD8 variants in four patients with CG-ASD and in one case with PCG. CPAMD8 is a gene of unknown function and recently associated with ASD. Bioinformatic and in vitro functional evaluation of the variants using quantitative reverse transcription PCR and minigene analysis supported a loss-of-function pathogenic mechanism. Optical and electron microscopy of the trabeculectomy specimen from one of the CG-ASD cases revealed an abnormal anterior chamber angle, with altered extracellular matrix, and apoptotic trabecular meshwork cells. The CPAMD8 protein was immunodetected in adult human ocular fluids and anterior segment tissues involved in glaucoma and ASD (i.e., aqueous humor, non-pigmented ciliary epithelium, and iris muscles), as well as in periocular mesenchyme-like cells of zebrafish embryos. CRISPR/Cas9 disruption of this gene in F0 zebrafish embryos (96 hpf) resulted in varying degrees of gross developmental abnormalities, including microphthalmia, pharyngeal maldevelopment, and pericardial and periocular edemas. Optical and electron microscopy examination of these embryos showed iridocorneal angle hypoplasia (characterized by altered iris stroma cells, reduced anterior chamber, and collagen disorganized corneal stroma extracellular matrix), recapitulating some patients' features. Our data support the notion that CPAMD8 loss-of-function underlies a spectrum of recessive CG-ASD phenotypes associated with extracellular matrix disorganization and provide new insights into the normal and disease roles of this gene.
Subject(s)
Complement C3/genetics , Extracellular Matrix/metabolism , Eye Abnormalities/genetics , Glaucoma/genetics , Loss of Function Mutation , Trypsin Inhibitor, Kazal Pancreatic/genetics , alpha-Macroglobulins/genetics , Adult , Animals , Anterior Chamber/metabolism , Anterior Chamber/pathology , Anterior Chamber/surgery , CRISPR-Cas Systems , Case-Control Studies , Complement C3/deficiency , Embryo, Nonmammalian , Extracellular Matrix/pathology , Eye Abnormalities/metabolism , Eye Abnormalities/pathology , Eye Abnormalities/surgery , Female , Gene Editing , Gene Expression , Genes, Recessive , Glaucoma/metabolism , Glaucoma/pathology , Glaucoma/surgery , High-Throughput Nucleotide Sequencing , Humans , Male , Middle Aged , Pedigree , Trabecular Meshwork/metabolism , Trabecular Meshwork/pathology , Trabecular Meshwork/surgery , Trabeculectomy , Trypsin Inhibitor, Kazal Pancreatic/deficiency , Zebrafish , alpha-Macroglobulins/deficiencyABSTRACT
The loss-of-function mutations of serine protease inhibitor, Kazal type 1 (SPINK1) gene are associated with human chronic pancreatitis, but the underlying mechanisms remain unknown. We previously reported that mice lacking Spink3, the murine homologue of human SPINK1, die perinatally due to massive pancreatic acinar cell death, precluding investigation of the effects of SPINK1 deficiency. To circumvent perinatal lethality, we have developed a novel method to integrate human SPINK1 gene on the X chromosome using Cre-loxP technology and thus generated transgenic mice termed "X-SPINK1". Consistent with the fact that one of the two X chromosomes is randomly inactivated, X-SPINK1 mice exhibit mosaic pattern of SPINK1 expression. Crossing of X-SPINK1 mice with Spink3+/- mice rescued perinatal lethality, but the resulting Spink3-/-;XXSPINK1 mice developed spontaneous pancreatitis characterized by chronic inflammation and fibrosis. The results show that mice lacking a gene essential for cell survival can be rescued by expressing this gene on the X chromosome. The Spink3-/-;XXSPINK1 mice, in which this method has been applied to partially restore SPINK1 function, present a novel genetic model of chronic pancreatitis.
