Apoptosis Inhibitor 5: A Multifaceted Regulator of Cell Fate.

Apoptosis, or programmed cell death, is a fundamental process that maintains tissue homeostasis, eliminates damaged or infected cells, and plays a crucial role in various biological phenomena. The deregulation of apoptosis is involved in many human diseases, including cancer. One of the emerging players in the intricate regulatory network of apoptosis is apoptosis inhibitor 5 (API5), also called AAC-11 (anti-apoptosis clone 11) or FIF (fibroblast growth factor-2 interacting factor).

Microbial Protein Binding to gC1qR Drives PLA2G1B-Induced CD4 T-Cell Anergy.

The origin of the impaired CD4 T-cell response and immunodeficiency of HIV-infected patients is still only partially understood. We recently demonstrated that PLA2G1B phospholipase synergizes with the HIV gp41 envelope protein in HIV viremic plasma to induce large abnormal membrane microdomains (aMMDs) that trap and inactivate physiological receptors, such as those for IL-7. However, the mechanism of regulation of PLA2G1B activity by the cofactor gp41 is not known.

PLA2G1B is involved in CD4 anergy and CD4 lymphopenia in HIV-infected patients.

The precise mechanism leading to profound immunodeficiency of HIV-infected patients is still only partially understood. Here, we show that more than 80% of CD4+ T cells from HIV-infected patients have morphological abnormalities. Their membranes exhibited numerous large abnormal membrane microdomains (aMMDs), which trap and inactivate physiological receptors, such as that for IL-7.

Surfactant-secreted phospholipase A interplay and respiratory outcome in preterm neonates.

Secreted phospholipase A hydrolyzes surfactant phospholipids and is crucial for the inflammatory cascade; preterm neonates are treated with exogenous surfactant, but the interaction between surfactant and phospholipase is unknown. We hypothesize that this interplay is complex and the enzyme plays a relevant role in neonates needing surfactant replacement. We aimed to: ) identify phospholipases A isoforms expressed in preterm lung; ) study the enzyme role on surfactant retreatment and function and the effect of exogenous surfactant on the enzyme system; and ) verify whether phospholipase A is linked to respiratory outcomes.

Antimalarial Activity of Human Group IIA Secreted Phospholipase A in Relation to Enzymatic Hydrolysis of Oxidized Lipoproteins.

The level of human group IIA secreted phospholipase A (hGIIA sPLA) is increased in the plasma of malaria patients, but its role is unknown. In parasite culture with normal plasma, hGIIA is inactive against , contrasting with hGIIF, hGV, and hGX sPLAs, which readily hydrolyze plasma lipoproteins, release nonesterified fatty acids (NEFAs), and inhibit parasite growth. Here, we revisited the anti- activity of hGIIA under conditions closer to those of malaria physiopathology where lipoproteins are oxidized.

Preparation of the Full Set of Recombinant Mouse- and Human-Secreted Phospholipases A.

A family of 14-20kDa, disulfide-rich, calcium-dependent secreted phospholipases A (sPLAs) that release fatty acids from the sn-2 position of glycerophospholipids can be found in mammals. They have a diverse array of tissue distribution and biological functions. In this chapter we provide detailed protocols for production of nearly all of the mouse and human sPLAs mainly by expression in bacteria and in vitro refolding or by expression in insect cells.

Secreted Phospholipases A2 Are Intestinal Stem Cell Niche Factors with Distinct Roles in Homeostasis, Inflammation, and Cancer.

The intestinal stem cell niche provides cues that actively maintain gut homeostasis. Dysregulation of these cues may compromise intestinal regeneration upon tissue insult and/or promote tumor growth. Here, we identify secreted phospholipases A2 (sPLA2s) as stem cell niche factors with context-dependent functions in the digestive tract.

Cross-reactivity of anti-PLA2R1 autoantibodies to rabbit and mouse PLA2R1 antigens and development of two novel ELISAs with different diagnostic performances in idiopathic membranous nephropathy.

About 70% of patients with idiopathic membranous nephropathy (iMN) have autoantibodies to the phospholipase A2 receptor PLA2R1. We screened sera from iMN patients for their cross-reactivity to human (h), rabbit (rb) and mouse (m) PLA2R1 by western blot (WB) and antigen-specific ELISAs. All iMN patients recognized hPLA2R1 and rbPLA2R1 by WB, and a rbPLA2R1 ELISA was as sensitive as the standardized hPLA2R1 ELISA to monitor anti-PLA2R1 in patients with active disease or in drug-induced remission.

In vitro anti-Plasmodium falciparum properties of the full set of human secreted phospholipases A2.

We have previously shown that secreted phospholipases A2 (sPLA2s) from animal venoms inhibit the in vitro development of Plasmodium falciparum, the agent of malaria. In addition, the inflammatory-type human group IIA (hGIIA) sPLA2 circulates at high levels in the serum of malaria patients. However, the role of the different human sPLA2s in host defense against P.

Pseudomonas aeruginosa eradicates Staphylococcus aureus by manipulating the host immunity.

Young cystic fibrosis (CF) patients' airways are mainly colonized by Staphylococcus aureus, while Pseudomonas aeruginosa predominates in adults. However, the mechanisms behind this infection switch are unclear. Here, we show that levels of type-IIA-secreted phospholipase A2 (sPLA2-IIA, a host enzyme with bactericidal activity) increase in expectorations of CF patients in an age-dependent manner.

The effect of group X secreted phospholipase A2 on fertilization outcome is specific and not mimicked by other secreted phospholipases A2 or progesterone.

Mouse group X sPLA2 (mGX) is an acrosomal protein playing an important role in fertilization and controlling acrosome reaction (AR) occurring during capacitation. We demonstrated previously that sperm from mGX knock-out mice had a severely impaired fertilization potential in vitro. We also showed that treatment of wild-type sperm with recombinant mGX during capacitation improved fertilization outcome.