In any authentic Semitic language: 
1) ’ aleph and ‘ ‘ayin are a glottal and a pharyngeal CONSONANTS (both lost in strongly europeanized Ivrit), no word can begin with a vowel!  
2) the word cannot begin with two consonants! (but cf. zman, kfar etc. in modern corrupted Ivrit),
3) two vowels can never go together not separated by one or two consonants, 
4) a is an auxiliary ultra-short vowel, inserted to facilitate pronunciation of the following pharyngeal ‘ (both lost in modern corrupted Ivrit). 

The Name of Messiah is strictly sacred not only as containing the FORBIDDEN (Ex=Šemōt “names” 20:7) TETRAGRAMMATON in the beginning (shortened to the first consonant in  Y--šū‘), but also because it is the Name of G-d Who reveals Himself to mankind as Man: „(Tetragrammaton) let save!”, read: Neither is there salvation in any other: for there is none other Name under Heaven given among men, whereby we must be saved (Peter Kepha, Acts=Ma‘asē haššehīm 4:12). 
As being the Single Ground of all what exists, G-d does not need any naming used by people to distinguish one matter from another: I AM That I AM
emōt 3:14). G-d said no Name to Moshe (Moses) because His all-embracing Unique Existence is exhaustively the Sinle Real Existence beyond the Universe and within it, thus being also the Single Name of all per se! 
G-D IS SPIRIT (Jn 4:24), therefore His Image and Likeness, after Which He created man, is That in Which He comes to man as Messiah. When coming to man as Man, He does have a human Name, and this is Y--šū‘  (-- = ē ).
People understood the Tertagrammaton as Name, but they were not modern civilised beasts unable to distinguish between holy and unholy. Therefore the Tetragrammaton became forbidden up to the times of today “civilisation-emancipation”. For those who still are not “civilised” and know how to defend Holiness from profanation (e.g. by occult satanists who can purposely soil sacred Name printed on paper), the Name of Messiah (Ma‘
asē haššehīm 4:12 above) should be protected especially! Therefore no full form of this Name is used here on this site. In order not to write unusual J-sus in English, a Greek-Latin Christogram JHS is introduced here. This Christogram is known to every student of theology of each Christian confession, not to say about any laic Catholic parishioner.
Take a positive example of authentic Semitic Islam where every mentioning of any sacred name is accompanied by a corresponding Arab expression. Everyone who violates this rule, automatically excludes himself from the community of faithful ones and denies own words.

All biblical personal names came into Latin from Greek Septuagint. However there are no consonant š (sh) in Greek differently from Hebrew. Therefore the consonant š (sh) had to be lost already in Greek. The first Hebrew consonant of Messiah's Name Y- had no analogue in Greek and in Latin: only the letter i was used there for the consonant y before vowels, as well as for the vowel i. Even more, any s between vowels could be pronounced only z in Latin. Thus Y--šū (its final Semitic pharyngeal ‘ had no correspondence in Greek and was lost) turned into Y--zu in Latin, spelled I--su, as in Greek (plus inflection of the nominative case -s in both languages). 
The way into English went through Latin. The first consonant got into English from the Latin Bible, but it was not replaced by English y and began to be pronounced [] according to English rules of pronunciation (cf. also Joseph, not Yoseph, etc.)
This name is a later shortened form of the Hebrew name
Y---šūa‘(--- =
). This shortening took place when Aramaic had already become dominant. However even this shape, in turn, is a shortened variant of the full original Biblic name  --hōjāšūa‘ (-- = Ye) “(let) THE NAME redeem” (THE NAME, Hebr. HaShem, is a traditional Jewish substitute instead of pronunciation of the forbidden Tetragrammaton).

[Minuscule letters render ultra-short vowels which are never accented. Very often the accent falls on the last syllable in Hebrew. h and are a voiceless and a voiced Semitic consonants correspondently, both absent in the languages of Europe. b corresponds to v, k and p correspond to kh [χ], f, -, ha- is a definite article, -īm, -ōt are nominal plural endings].