Free factor XIII activation peptide affects factor XIII function

Molecular Basis of Congenital Factor XIII Deficiency in Iran

Factor XIII deficiency (FXIIID) is an extremely rare autosomal recessive disorder that has the highest incidence in Iran. The FXIIID is primarily due to mutations in the FXIII-A gene, most of which are unique. In the current study, we report all identified mutations among Iranian patients. Among 483 patients, 366 (75.8%) were molecularly analyzed; 11 different mutations were observed. Of 11, 8 (72.7%) are missense, whereas the remaining 3 (27.3%) are deletion/insertion. Among these patients, 347 (94.9%) had the unique mutation of c.562T>C and 5 (1.4%) had the c.233G>A mutation. c.1226G>A, c.2111G>A, and c.1142T>A are also common, whereas other mutations, including 3 missense and 3 deletion/insertion, were observed only in single patient. Although, in most cases, FXIII mutations are unique and restricted to a specific family, this differs in Iran where a considerable number of identified mutations, recurrently observed, appear to be due to the high rate of consanguinity.

Revisiting the mechanism of coagulation factor XIII activation and regulation from a structure/functional perspective

The activation and regulation of coagulation Factor XIII (FXIII) protein has been the subject of active research for the past three decades. Although discrete evidence exists on various aspects of FXIII activation and regulation a combinatorial structure/functional view in this regard is lacking. In this study, we present results of a structure/function study of the functional chain of events for FXIII. Our study shows how subtle chronological submolecular changes within calcium binding sites can bring about the detailed transformation of the zymogenic FXIII to its activated form especially in the context of FXIIIA and FXIIIB subunit interactions. We demonstrate what aspects of FXIII are important for the stabilization (first calcium binding site) of its zymogenic form and the possible modes of deactivation (thrombin mediated secondary cleavage) of the activated form. Our study for the first time provides a structural outlook of the FXIIIA₂B₂ heterotetramer assembly, its association and dissociation. The FXIIIB subunits regulatory role in the overall process has also been elaborated upon. In summary, this study provides detailed structural insight into the mechanisms of FXIII activation and regulation that can be used as a template for the development of future highly specific therapeutic inhibitors targeting FXIII in pathological conditions like thrombosis.

Ibrutinib for mantle cell lymphoma

Mantle cell lymphoma (MCL) is a rare and aggressive form of non-Hodgkin lymphoma. Ibrutinib is a first-in-class, oral inhibitor of Bruton's tyrosine kinase which acts by downstream inhibition of the B-cell receptor. Early clinical trials have demonstrated excellent tolerability and a modest side-effect profile in relapsed/refractory MCL. Although the majority of disease responses are partial, efficacy data are impressive with more than two-thirds of patients demonstrating a durable response. This article focuses on all aspects of ibrutinib in the context of MCL, including a summary of the basic pharmacology and pharmacokinetics; a review of the safety and efficacy data published to date and a discussion of the future implications in MCL.