The defective secretion of a naturally occurring alpha-1-antichymotrypsin variant with a frameshift mutation

The delicate balance between secreted protein folding and endoplasmic reticulum-associated degradation in human physiology

Protein folding is a complex, error-prone process that often results in an irreparable protein by-product. These by-products can be recognized by cellular quality control machineries and targeted for proteasome-dependent degradation. The folding of proteins in the secretory pathway adds another layer to the protein folding "problem," as the endoplasmic reticulum maintains a unique chemical environment within the cell. In fact, a growing number of diseases are attributed to defects in secretory protein folding, and many of these by-products are targeted for a process known as endoplasmic reticulum-associated degradation (ERAD). Since its discovery, research on the mechanisms underlying the ERAD pathway has provided new insights into how ERAD contributes to human health during both normal and diseases states. Links between ERAD and disease are evidenced from the loss of protein function as a result of degradation, chronic cellular stress when ERAD fails to keep up with misfolded protein production, and the ability of some pathogens to coopt the ERAD pathway. The growing number of ERAD substrates has also illuminated the differences in the machineries used to recognize and degrade a vast array of potential clients for this pathway. Despite all that is known about ERAD, many questions remain, and new paradigms will likely emerge. Clearly, the key to successful disease treatment lies within defining the molecular details of the ERAD pathway and in understanding how this conserved pathway selects and degrades an innumerable cast of substrates.

Traffic jam: a compendium of human diseases that affect intracellular transport processes

As sequencing of the human genome nears completion, the genes that cause many human diseases are being identified and functionally described. This has revealed that many human diseases are due to defects of intracellular trafficking. This 'Toolbox' catalogs and briefly describes these diseases.

alpha 1-antitrypsin TAQ I polymorphism and alpha 1-antichymotrypsin mutations in patients with obstructive pulmonary disease

Obstructive pulmonary disease is a multifactorial condition deriving from the interaction of environmental and genetic factors. From biochemical knowledge of the basis of the disease, alpha 1-antitrypsin and alpha 1-antichymotrypsin are considered two likely candidate genes. We therefore designed an association study comprising 232 unrelated Italian individuals divided as follows: 89 individuals with obstructive lung disease (66 with COPD and 23 with disseminated bronchiectasis) and 143 controls (45 patients with non-obstructive lung disease and 98 healthy individuals). We screened for Taq I (G1237A) polymorphism of the alpha 1-antitrypsin gene as well as the rare variants Bonn-1 (Pro229Ala), Bochum-1 (Leu55Pro), Isehara-1 (Met389Val) and Isehara-2 (1258delAA), and the common signal peptide polymorphism Thr-15Ala of the alpha 1-antichymotrypsin gene. The frequencies of Taq I G1237A alleles were 11.7 and 10.8% in obstructed patients and controls, respectively (P = 0.43), while those of signal peptide Thr-15Ala alleles were 51.6 and 50.3% in obstructed patients and controls, respectively (P = 0.42). We conclude that alpha 1-antitrypsin Taq I polymorphism and alpha 1-antichymotrypsin Thr-15Ala mutation are not major genetic risk factors for the development of obstructive lung disease in Italian patients. The alpha 1-antichymotrypsin rare variants were not detected: our results do not exclude the possibility that other alpha 1-antichymotrypsin gene mutations might be present in Italian obstructed patients but, if so, these genetic defects must be rare.