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Physiology

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Central Nervous System

Question
2 out of 23
 

Memory cells escape apoptosis because of? (AIIMS NOV 2009)



A Nerve growth factor

B Platelet derived growth factor

C Fibroblast growth factor

D Insulin like growth factor

Ans. A Nerve growth factor

I. Memory cells behave like immortalized cells, with no requirement for antigen signaling to survive. These cells can respond more rapidly to antigen.

II. These characteristics of memory cells are potentially due to an altered chromatin state of cytokine genes, a higher expression of adhesion factors which helps to lower the threshold needed for signaling, and a higher expression level of anti-apoptotic factors such as Bcl-2 Q.

III. Growth factors can work to inhibit the apoptotic pathways. For example, some growth factors activate PI3 kinase, which activates Akt. The activated protein Akt inactivates procaspase-9 & inhibits FasL synthesis.

IV. The most important growth factor in this regard is Nerve growth factor(NGF). Although others like IGF,PDGF & FGF can also prolong the survival.

Survival of memory B lymphocytes is tightly linked to the integrity of the Bcl-2 protein and is regulated by a nerve growth factor (NGF) autocrine circuit

Central Nervous System Flashcard List

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