BIO 344 1st Edition Lecture 20 Outline of Last Lecture I. Micro RNAsa. Lin4 and lin14b. miRNA transcriptionc. miRNA silencingd. capOutline of Current Lecture I. Prionsa. Diseasesb. Structurec. transmissionCurrent LecturePrions- proteinaceous infection= priono misfolded PrP protein (prion protein)o changes shape of properly folded proteins to mimic their own misfolded shapeo these misfolded proteins aggregate and cause cell death- diseaseso Mad Cows Disease= bovine spongiform encephalopathy (BSE)o Transmissible Spongiform Ecenephalapathy (TSE)—humanso Kuru—humans, Papua New Guinea Custom for women and children to eat the flesh and brains of relatives that died- Some of which had died from prion disease, so they were eating misfolded PrPThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- This made it appear that prion disease was genetico CJD—“human mad cow’s disease” from eating infected cow meat- Structureo No genetic component—no nucleic acidso PrP protein plays a role in signal transduction This protein is found in brain cell membraneo PrPc= PrP cellular, normal PrP Composed of alpha helices Exists as a monomero PrPRes= resistant to enzymatic degradation Composed of very stable beta-pleated sheets Forms aggregates Resistant to digestion by proteaseK- Transmissiono Mechanisms of transmission Eating infected cow meat For Kuru, possible mechanism is when infected brains were eaten, nutrients get digested, transported to the blood stream, and to the capillaries to feed the brain (normal digestive pathway)- However, many nutrients are typically impermeable to the blood brain barrier (crossing from the capillaries into the brain) in order to protect the brain- PrP is capable of penetrating the blood brain barriero Enters brain, binds to normal proteins and cause them to misfold into PrPRes-like shapeo Like a zombie Spontaneous misfolding (less likely)o Different PrP misfolds/shape different prion diseaseso It is possible to transmit between species, but very rareo Infected PrP must be similar to the host PrP in order to infecto Becomes progressively easier to pass on with continued passage Spontaneous refold of PrPRes results in a version better at causing misfolds in the hose
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