Mosquito-borne weeks, the infected hepatocytes mature into schizonts. In

          Mosquito-borne disease  which is Malaria can  infected people to become  sick with high fever, chills, and flu-like
illness.  The most dangerous it can also
cause death. According to National Institute of Allergy , and Infectious
Diseases (NIAID) ,

substantial progress has
been made globally to control and eliminate malaria, but it continues to be a
significant public health problem with roughly 3.2 billion people worldwide at
risk for the disease.

We Will Write a Custom Essay Specifically
For You For Only $13.90/page!


order now

         Malaria is disease that are responsible
globally for 500 million cases of clinical disease and presents a public health
problem for 2.4 billion people in over 90 countries representing  40% of the world’s population. ( Malaria
Foundation International).

         There
are four species of protozoan parasites in Malaria human which the genus is Plasmodium:
P. falciparum, P. vivax, P. ovale, and P. malariae.
Although P. vivax is responsible for most malaria infections
in the world, the most severe form of malaria is caused by P.
falciparum. The severity of malarial illness depends largely on the
immunological status of the person who is infected. Partial immunity develops
over time through repeated infection, and without recurrent infection, immunity
is relatively short-lived. (Institute
of Medicine (US) Committee for the Study on Malaria Prevention and Control ,
1991 ).     The
human  stage of the life cycle begins
with the exoerythrocytic phase. When an infected mosquito bites a human,  sporozoites in the mosquito’s saliva enter
the bloodstream . The sporozoites travel to the liver, where they invade
hepatocytes over a period of up to 4 weeks, the infected hepatocytes mature
into schizonts. In Plasmodium vivax and P.
ovale infections only, some schizonts may remain
dormant as hypnozoites for weeks to years before causing clinical relapses.
With schizont rupture, merozoites are released into the bloodstream . In the
erythrocytic phase, merozoites invade erythrocytes and either undergo an
asexual cycle of reproduction or develop into non multiplying sexual forms
gametocytes. These gametocytes are crucial for perpetuating the life cycle, as
they are ingested by a feeding mosquito and undergo sexual reproduction within
the mosquito midgut; thousands of infective sporozoites are produced, which
then migrate to the salivary glands, ready to initiate another life cycle ( Suh
et al., 2004 ).1.2 Drug resistant problemIn general, malaria is a
curable disease, and if everyone has access to early treatment, nobody should
die from it. For the past 50 years, there have been two main classes of
antimalarial agents in use, the antifolates and the cinchona alkaloids or the
quinoline-containing drugs. In most cases, these agents are targeted at the
asexual erythrocytic stage of the parasite ( Philips , 2001 ).Antimalarial
drug resistance has confront with one of the greatest challenges facing malaria
control nowadays. According to Peter B. Bloland, (2001),  the 
definition of resistance is ability of a parasite strain to survive
and/or multiply despite the administration and absorption of a drug given in
doses equal to or higher than those usually recommended but within tolerance of
the subject then to specify that the drug must gain access to the parasite or
the infected red blood cell for the duration of the time necessary for its
normal action . Drug resistance has been implicated in the
spread of malaria to new areas and re-emergence of malaria in areas where the
disease had been eradicated. Drug resistance has also played a significant role
in the occurrence and severity of epidemics in some parts of the world.
Population movement has introduced resistant parasites to areas previously free
of drug resistance. The economics of developing new pharmaceuticals for
tropical diseases, including malaria, are such that there is a great disparity
between the public health importance of the disease and the amount of resources
invested in developing new cures . This disparity comes at a time when malaria
parasites have demonstrated some level of resistance to almost every
antimalarial drug currently available, significantly increasing the cost and
complexity of achieving parasitological cure.The
goal of antimalarial drug resistance monitoring has been to detect cases of
treatment failure caused by drug-resistant parasites before they become
widespread in the population and lead to increased morbidity and mortality.
This is deceptively simple, because recurrent parasitemia in endemic countries
can also result from a host of other factors including noncompliance, poor
quality drug, inadequate drug levels, new infection and even varying levels of
immunity to malaria.  Artemisinin 
therapies (ACT), in which more than one drug is mixed together to
prevent the parasite from developing resistance to any one treatment, is a far
more effective therapy than pure chloroquine. However, ACTs cost 10 times more
than mono-drug therapy. Since pharmaceutical companies stand to gain little
financially from ACT sales in the developing world, their use remains low as no
incentive structure exists to encourage their wider distribution (Arrow et.al.,2005). There are 
many factors that have been associated with antimalarial drug resistance
include such disparate issues as human behaviour ,vector and parasite biology,
pharmacokinetics, and economics. Futhermore, the  factor  that decrease the effectiveness of the immune
system in clearing parasite residuum after treatment also appear to increase
survivorship of parasites and facilitate development and intensification of resistance.
This mechanism has been suggested as a significant contributor to resistance in
South-East Asia, where parasites are repeatedly cycled through populations of
non-immune individuals.1.3 Why kinase is the target
for new malaria drug.In eukaryotic cells, protein
kinases are known to play key roles in cell cycle regula? tion and signaling
pathways. Protein kinases are fascinating biological catalysts with a rapidly
expanding knowledge base, a growing appreciation in cell regulatory control,
and an ascendant role in successful therapeutic intervention protein kinases make up almost 2% of the human
genome and control most important biological processes.The activity of
cAMP?dependent protein kinase (PKA) depends on A?kinase anchoring proteins
(AKAPs) through protein interactions. While several components of the cAMP
dependent pathway includ?ing the PKA catalytic and regulatory subunits—have
been characterized in P. falciparum, whether AKAPs are involved in this pathway
remains unclear. Here, PfAKAL, an open reading frame of a potential AKAP?like
protein in the P. falciparum genome was identified, and its protein partners
and putative cellular functions characterized.Identification and validation of the target as
the true direct driver is the most important step in drug discovery, or in
association with other proteins may cause an altered pathological phenotype.
Many failures during the drug discovery process are ascribed mainly to a wrong
target, or that the animal model does not mimic the exact phenotype in humans.
Other factors such as physicochemical properties, poor absorption,
distribution, metabolism and excretion characteristics and in vivo
toxicological outcomes also impact the attrition rate of drug candidates (
Waring et al. , 2015).Most kinases are promiscuous
and will catalyze the phosphotransfer from ATP to alternative substrates with
differing degrees of catalytic efficiency. Protein kinases (PKs) catalyze the phosphorylation of
proteins at serine, threonine and tyrosine residues. This post-translation
modification is important to most physiological processes; there are hundreds
of different protein kinases that catalyze specific phosphorylation reactions.
Kinases are important targets for drug discovery with now over 30 medicines
approved that inhibit protein kinases .(Haubrich and Swinney , 2016).                                                    CHAPTER
2 MOLECULAR CHARACTERIZATION OF MALARIA KINASE2.1  Calcium Dependent Protein Kinase 1 (CDPK1)According to Garcia (1999), the presence of
calcium in the medium used in the culture of P. falciparum is required
for parasite invasion of erythrocytes and that chelating calcium in infected
erythrocytes results in developmental arrest and impairs parasite invasion in
culture.In Plasmodium falciparum,
calcium-dependent protein kinase 1 (PfCDPK1) is expressed during schizogony in
the erythrocytic stage as well as in the sporozoite stage. It is coexpressed
with genes that encode the parasite motor complex, a cellular component
required for parasite invasion of host cells, parasite motility and potentially
cytokinesis. It does cause the sudden
arrest of developmental progression in late schizogony, resulting in a
reduction in the number of ring-stage parasites in culture.  From Kato et al.,(2008) findings, along with
the results obtained by the ontology-based pattern identification analysis,
strongly suggest that PfCDPK1 is involved in regulating parasite
motor-dependent processes that occur in the late schizont stage. These may
include cytokinesis, egress and invasion, all of which are closely linked in
malaria parasites.                 Recently, Plasmodium falciparum calcium-dependent protein
kinase 1 (PfCDPK1) has been found in the membrane and organelle fraction of the
parasite. The kinase contains three motifs for membrane binding at its
N-terminus, a consensus sequence for myristoylation, a putative palmitoylation
site and a basic motif.Knockdown
of CDPK1 in sexual stages resulted in developmentally arrested parasites and
prevented mosquito transmission, and these effects were independent of the
previously proposed function for CDPK1 in regulating parasite motility.
In-depth translational and transcriptional profiling of arrested parasites
revealed that CDPK1 translationally activates mRNA species in the developing
zygote that in macrogametes remain repressed via their 30 and 50 UTRs. These
findings indicate that CDPK1 is a multifunctional protein that translationally
regulates mRNAs to ensure timely and stage-specific protein expression.          ( Sarah et al., 2012)2.2.  Calcium Dependant Protein Kinase 4 (CDPK4) According to Oliver (2004), a member of a
family of plant-like calcium dependent, CDPK4, is identified as the molecular  switch that translates the xanthurenic
acid (XA)
which is small mosquito molecule induced calcium signal  into a cellular response by regulating cell
cycle pro- during gametogenesis in Plasmodium
berghei, a malaria parasite gression in the male gametocyte. CDPK4 is shown
be essential for the sexual reproduction and mosquito specialized of  P.
berghei. The study from an unexpected function for a plant-like signaling
pathway in   cell cycle regulation and life cycle
progression of  malaria parasite.Their developmental regulation makes these
kinases prime candidates for the molecular switches that translate ubiquitous
Ca2+ signals into appropriate cellular responses at specific
stages of the parasite’s life cycle.CDPK4 triggers cell cycle progression by
initiating the raoid threefold replication of the genome that is completed with
about 8 minute of activation (Billker et al.,20014). It is also essential to
induce to the three rounds of mitosis that take place in parallel with DNA
replication and to initiate the polymerization of axonmes that form the motile
backbone of the microgamets ( Tewari et al ., 2005).According to Sarah (2012),
CDPK4 is the Ca2+  kinase critical for initiation od DNA
replication during the first minute afer microgametocytes activation but this
kinase was not required for the emergence of gametocytes from their host cells
leading to the other calcium effectors that invoved.     2.3
Mitogen – associated Protein Kinase 2 (MAPK2)            The purified recombinant enzyme displayed functional
characteristics of MAPKs such as (i) ability to undergo autophosphorylation,
play
important roles in signal transduction pathways regulating adaptative response
to a wide range of stimuli. Several pathways involving different MAP kinases
coexist in the cell (ii) ability to phosphorylate myelin basic protein, a
classical MAPK substrate, (iii) regulation of kinase activity by a
MAPK-specific phosphatase, and (iv) ability to be activated by component(s)
present in cell extracts. Mutational analysis of the recombinant protein allowed
the identification of residues that are important for enzymatic activity.              CHAPTER 3 SUBSTRATE IDENTIFICATION OF MALARIA KINASE3.1  Casein Kinase I (CKI)Casein kinase I (CKI) was one of the first
serine/threonine protein kinase activities to be isolated and characterised that
phosphorylates a large number of protein substrates .The casein kinase I (CKI)
isoforms from yeast have been genetically linked to vesicular trafficking, DNA
repair, cell cycle progression and cytokinesis.CKI was found to be highly conserved in all
organisms which perform various functions in both the cytoplasm and nucleus,
such as DNA repair, cell
cycle, cytokinesis, vesicular trafficking, morphogenesis and
circadian rhythm.CKI uses ATP as a phosphate donor to phosphorylate serine and
threonine residues of target proteins. Many proteins, such as glycogen
synthase, tumor suppressor p53, the cAMP-responsive element modulator (CREM),
and the type I protein phosphatase inhibitor-2 are substrates of CK1.CKI contains a highly conserved kinase domain
responsible for catalytic activity at the N-terminus and a highly diverse
regulatory domain responsible for both regulation of kinase activity and
subcellular targeting at the C-terminus. 3.2  Casein Kinase ?(CK?)            Mammalian
protein kinase CK2 is a pleiotropic serine/ threonine protein kinase know to
act on hundreds of cellular substrates involved in crucial cellular processes
such as differentiation, proliferation, apoptosis, stress response, DNA damage
and circadian rhythm.            CK2 was constitutively
active in unfertilized and fertilized oocytes. The enzymatic activity
oscillated through meiosis showing three major peaks: soon after fertilization
(metaphase I exit), before metaphase II, and at the exit from metaphase I
(Holland et al.,2008).            CK2 catalyzes the
phosphorylation of a great number of substrates presenting multiple acidic
residues surrounding the phosphoacceptor amino acid and  the potential role of PfCK2 in the nucleus
has identified a number of interacting partners and substrate nuclear proteins
involved in chromatin assembly and dynamics( Graciotti et al.,2014).                  CHAPTER 4DISCUSSION4.1 Potential as a new
malarial drug target            New
opportunities to discover medicines for neglected diseases can be leveraged by
the extensive kinase tools and knowledge created in targeting human kinases.The
protein kinase is in its relevant state of activation with the relevant
substrates present; this only selects cell penetrant compounds and compounds
that have a lethal effect; it would detect compounds that were acting on
multiple proteins. The disadvantages of this approach include the unknown
identity of the target(s), which could make optimization of hits problematic,
particularly if there were pharmacokinetic or toxicological issues.( Irene ,2017)4.2 Controvercy of
antimalarial drug resisstance            Anti-malarial
resistance, especially to artemisinin-based combination therapy (ACT), is a
major threat to malaria control efforts. Resistance generally results from
inappropriate, incomplete or inadequate courses of treatment. This most
commonly occurs in the context of poverty, counterfeit medications, and weak
healthcare infrastructure. ( World Malaria Report 2012).        CHAPTER 5CONCLUSION             A molecular understanding of the life cycle of P.
falciparum will facilitate the rational design of new therapies. Efficient
egress of P. falciparum out of an infected human red blood cell is a
fundamental step in the parasite life cycle.